• Age 18 years or older
• Histologically confirmed metastatic clear cell Renal Cell Carcinoma and has progressed on/after one front-line treatment regimen
• Must have archived or fresh tissue biopsy for biomarker testing
• Must have radiologic imaging with a computerized tomography (CT) scan or magnetic resonance imaging (MRI) within 21 days of enrollment
• Must have at least one measurable lesion according to RECIST 1.1
• ECOG performance status of 0-1
• Adequate gastrointestinal (GI), bone marrow, liver and kidney function
• Life expectancy minimum of >12 weeks
• At least 14 days between termination of prior anticancer or radiation therapy and administration of AVB-S6-500
• Received prior treatment with cabozantinib
• Currently being treated with concurrent anti-cancer therapy or any other interventional treatment or other interventional research trial
• Significant cardiac disease history
• Has other prior malignancy within the past 3 years except adequately treated basal or squamous cell skin cancer, superficial bladder cancer or carcinoma in situ of the prostate, cervix or breast
• Symptomatic CNS metastasis or metastases
• Active GI disease that would impact absorption of cabozantinib
• Nephrotic range proteinuria at screening
• Active intervention for pleural effusion (ie, thoracentesis within the past month)
• Has had a major bleed in the last 3 months, uncontrolled hypertension despite treatment with Antihypertensives or is not appropriate for treatment with cabozantinib in the Investigator's opinion
• Serious active infection requiring IV antibiotics and/or hospitalization at study entry
• Has active, suspected, or previously documented autoimmune disease, defined as requiring systemic treatment
• Has known human immune deficiency (HIV) syndrome, hepatitis B, or hepatitis C

1. Radiographic evidence of renal cancer with IVC tumor thrombus 2. Tumor thrombus must be ≥ level II (As per Mayo classification, it would be ≥ level I [Refer to NEVES, R. and ZINCKE, H. (1987), Surgical Treatment of Renal Cancer with Vena Cava Extension. British Journal of Urology, 59: 390-395. doi:10.1111/j.1464-410X.1987.tb04832.x]) 3. Patient eligible for SABR to the IVC tumor thrombus as decided by the treating radiation oncologist 4. Patient eligible for IVC tumor thrombectomy as decided by the treating urologist 5. Any number of metastatic disease is allowed in the Pilot phase of the trial • For Phase II, metastatic patients will be allowed only if all sites of metastasis has been treated either surgically or radio-surgically (If limited sites of metastasis are present, all of which can be resected during the nephrectomy, then the patient can be eligible) 6. Age ≥ 18 years. 7. Performance status ECOG 0-2 8. Any serum Albumin is allowed, but ≥ 3.4 g/dL is strongly encouraged • Serum albumin <3.4 is a significant predictor of peri-operative mortality(12) 9. Any serum AST is allowed but serum AST ≤ 34 IU/L is strongly encouraged • Significant predictor of mortality in univariate but not multivariate analysis(12) 10. Women of childbearing potential and men must agree to use adequate contraception (hormonal such as birth control pills, patch or ring; Depo-Provera, Implanon or barrier method, such as condom or diaphragm used with a spermicide of birth control; abstinence) prior to study entry, for the duration of study treatment, and for 90 days following completion of radiation therapy. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. 10.1 A female of childbearing potential is any woman (regardless of sexual orientation, marital status, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria:
• Has not undergone a hysterectomy or bilateral oophorectomy; or
• Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months). 11. Ability to understand and the willingness to sign a written informed consent. 12. Subjects must be able to undergo either MRI or CT. 1. Subjects who have had radiotherapy to a target within 3 cm of the IVC tumor thrombus. 2. Subjects may have received any other investigational agents or chemotherapy as long as they are eligible for SABR and surgery 3. Subjects with brain metastases should be excluded from this clinical trial unless all the metastasis are treated surgically or radio-surgically 4. Subjects with a history of pulmonary embolism is excluded 5. Subjects with a history of pulmonary hypertension is excluded 6. Subjects must not be pregnant due to the potential for congenital abnormalities. 7. Contraindication for contrast-enhanced MRI as defined by the standard operating procedures of the Department of Radiology at UT Southwestern. Briefly, these include medically unstable; cardiac pacemaker; intracranial clips, metal implants; metal in the eyes; pregnant or nursing; claustrophobia; and impairment of the renal function with estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73m2. Patients with one or more of these contraindications but eligible to undergo contrast-enhanced CT can participate in this study and will not receive an MRI

• Patients with suspected renal cell carcinoma with planned surgery or patients with metastatic RCC and a tissue diagnosis. (In standard clinical practice, biopsy is not routinely performed in patients who will be having surgery).
• Ability to understand and the willingness to sign a written informed consent.
• Patient must be able to lie still for a 30 to 60 minute PET/CT scan.
• One of the following: 1. Patients with locally advanced RCC planned for surgery determined to be a high risk of recurrence, defined by presence of at least clinical T2 or thioredoxin 1 (TxN1), OR patients with metastatic RCC for whom treatment with metastasectomy is planned by the treating physician. 2. Patients with metastatic RCC for whom immuno-oncology (IO) therapy is planned.
• Women of child-bearing potential must agree to undergo and have documented a negative pregnancy test on the day of 89Zr-DFO-Atezolizumab administration. A female of child-bearing potential is any woman (regardless of sexual orientation, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria:
• Has not undergone a hysterectomy or bilateral oophorectomy; or
• Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months).
• History of severe allergic, anaphylactic, or other hypersensitivity reactions to atezolizumab or any other chimeric or humanized antibodies.
• Concurrent use of an immune checkpoint inhibitor (ICI).
• Uncontrolled severe and irreversible intercurrent illness or psychiatric illness/social situations that would limit compliance with study requirements.
• Subjects must not be pregnant or nursing due to the potential for congenital abnormalities and the potential of this regimen to harm nursing infants.
• Significant autoimmune disease requiring treatment with either prednisone (or steroid equivalent) at a dose > 10 mg/day or other immunosuppressive agents. (Replacement steroid therapy is acceptable).
• Any patient for whom ICI therapy would be contraindicated for other reasons. Patients with adverse reactions to ICI therapy may undergo second 89Zr-DFO-Atezolizumab injection and PET/CT at the discretion of the treating physician considering that the dose of antibody represents 1% of a single therapeutic dose and therefore unlikely to cause adverse events.
• Subjects unable to provide informed consent.
• Subjects who are claustrophobic or have other contraindications to PET/CT.
• Subjects must not weigh more than the maximum weight limit for the table for the PET/CT scanner where the study is being performed. (>200 kg or 440 lbs).

• Has a histologically confirmed diagnosis of locally advanced/metastatic ccRCC
• Has received no prior systemic therapy for advanced RCC; prior neoadjuvant/adjuvant therapy for RCC is acceptable if completed ≥12 months before randomization/allocation
• Is able to swallow oral medication
• Has adequate organ function
• Participants receiving bone resorptive therapy must have therapy initiated at least 2 weeks before randomization/allocation
• Has resolution of toxic effects of the most recent prior therapy to ≤Grade 1
• If participants receive major surgery or radiation therapy, they must have recovered from complications from the intervention
• Has adequately controlled blood pressure (BP ≤150/90 mm Hg) with no change in hypertensive medications within 1 week before randomization/allocation
• Male participants are abstinent from heterosexual intercourse or agree to use contraception during treatment with and for at least 7 days after the last dose of lenvatinib and /or belzutifan; 7 days after lenvatinib and/or belzutifan is stopped, if the participant is only receiving pembrolizumab, pembrolizumab/quavonlimab, favezelimab/pembrolizumab or a combination of the aforementioned drugs, no contraception is needed
• Female participant is not pregnant or breastfeeding and is not a woman of childbearing potential (WOCBP) or is a WOCBP abstinent from heterosexual intercourse or using contraception during the intervention period and for at least 120 days after the last dose of pembrolizumab, pembrolizumab/quavonlimab, favezelimab/pembrolizumab for 30 days after the last dose of lenvatinib or belzutifan, whichever occurs last
• Has urine protein ≥1 g/24 hours and has any of the following: (a) hypoxia defined as a pulse oximeter reading <92% at rest, or (b) requires intermittent supplemental oxygen, or (c) requires chronic supplemental oxygen
• Has clinically significant cardiovascular disease within 12 months from the first dose of study intervention administration
• Has had major surgery within 3 weeks before first dose of study interventions
• Has a history of lung disease
• Has a history of inflammatory bowel disease
• Has preexisting gastrointestinal (GI) or non-GI fistula
• Has malabsorption due to prior GI surgery or disease
• Has received prior radiotherapy within 2 weeks of start of study intervention
• Has received a live or live attenuated vaccine within 30 days before the first dose of study drug; killed vaccines are allowed
• Has received more than 4 previous systemic anticancer treatment regimens
• Has a diagnosis of immunodeficiency or is receiving any form of immunosuppressive therapy within 7 days prior to the first dose of study intervention
• Has known additional malignancy that is progressing or has required active treatment within the past 3 years
• Has known central nervous system (CNS) metastases and/or carcinomatous meningitis
• Has an active autoimmune disease that has required systemic treatment in the past 2 years; replacement therapy is not considered a form of systemic treatment and is allowed
• Has an active infection requiring systemic therapy
• Has a known history of human immunodeficiency virus (HIV) infection
• Has a known history of Hepatitis B
• Has had an allogenic tissue/solid organ transplant

• Has histologically confirmed diagnosis of RCC with clear cell component
• Has received no prior systemic therapy for advanced ccRCC
• Male participants are abstinent from heterosexual intercourse or agree to use contraception during and for at least 7 days after last dose of study intervention with belzutifan and lenvatinib
• Female participants are not pregnant or breastfeeding and are either not a woman of child-bearing potential (WOCBP) or use a contraceptive method that is highly effective or are abstinent from heterosexual intercourse during the intervention period and for at least 120 days after pembrolizumab or pembrolizumab/quavonlimab or for at least 30 days after last dose of lenvatinib or belzutifan, whichever occurs last
• Has adequately controlled blood pressure with or without antihypertensive medications
• Has adequate organ function
• Participants receiving bone resorptive therapy must have therapy initiated at least 2 weeks prior to randomization/allocation
• Has a known additional malignancy that is progressing or has required active treatment within the past 3 years
• Has had major surgery, other than nephrectomy within 4 weeks prior to randomization
• Has known central nervous system (CNS) metastases and/or carcinomatous meningitis
• Has received prior radiotherapy within 2 weeks prior to first dose of study intervention
• Has hypoxia or requires intermittent supplemental oxygen or requires chronic supplemental oxygen
• Has clinically significant cardiac disease within 12 months from first dose of study intervention
• Has a history of interstitial lung disease
• Has symptomatic pleural effusion; a participant who is clinically stable following treatment of this condition is eligible
• Has preexisting gastrointestinal or non-gastrointestinal fistula
• Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of study treatment
• Has a known psychiatric or substance abuse disorder that would interfere with requirements of the study
• Has received a live or live-attenuated vaccine within 30 days before the first dose of study drug; killed vaccines are allowed
• Has an active autoimmune disease that has required systemic treatment in the past 2 years
• Has a history of noninfectious pneumonitis that required steroids or has current pneumonitis
• Has an active infection requiring systemic therapy
• Has a known history of human immunodeficiency virus (HIV) infection
• Has a known history of Hepatitis B
• Has radiographic evidence of intratumoral cavitation, encasement or invasion of a major blood vessel
• Has clinically significant history of bleeding within 3 months prior to randomization
• Has had an allogenic tissue/solid organ transplant

• Has a histologically confirmed diagnosis of locally advanced/metastatic ccRCC
• Has experienced disease progression on or after having received systemic treatment for locally advanced or metastatic RCC with a PD-(L)1 checkpoint inhibitor (in sequence or in combination with a vascular endothelial growth factor
•tyrosine kinase inhibitor [VEGF-TKI]) where PD-(L)1 checkpoint inhibitor treatment progression is defined by meeting ALL of the following criteria: (a) has received ≥2 doses of an anti-PD-(L)1 monoclonal antibody (mAb) (b) has shown radiographic disease progression during or after an anti-PD-(L)1 mAb as defined by RECIST 1.1 by investigator (c) disease progression has been documented within 12 weeks from the last dose of an anti-PD-(L)1 mAb
• Has experienced disease progression on or after having received systemic treatment for locally advanced or metastatic RCC with a VEGF-TKI (in sequence or in combination with a PD-[L]1 checkpoint inhibitor) where VEGF-TKI treatment progression is defined by meeting the following criterion: has shown radiographic disease progression during or after a treatment with a VEGF-TKI as defined by RECIST 1.1 by investigator
• Is able to swallow oral medication
• Has adequate organ function
• Participants receiving bone resorptive therapy must have therapy initiated at least 2 weeks before randomization/allocation
• Has resolution of toxic effects of the most recent prior therapy to ≤Grade 1
• If participants receive major surgery or radiation therapy, they must have recovered from complications from the intervention
• Has adequately controlled blood pressure (BP ≤150/90 mm Hg) with no change in hypertensive medications within 1 week before randomization/allocation
• Male participants are abstinent from heterosexual intercourse or agree to use contraception during treatment with and for at least 7 days after the last dose of lenvatinib and /or belzutifan; 7 days after lenvatinib and/or belzutifan is stopped, if the participant is only receiving pembrolizumab, pembrolizumab/quavonlimab, favezelimab/pembrolizumab, MK-4830 or a combination of the aforementioned drugs, no contraception is needed
• Female participant is not pregnant or breastfeeding and is not a woman of childbearing potential (WOCBP) or is a WOCBP abstinent from heterosexual intercourse or using contraception during the intervention period and for at least 120 days after the last dose of pembrolizumab, pembrolizumab/quavonlimab, favezelimab/pembrolizumab, MK-4830 or 30 days after the last dose of lenvatinib or belzutifan, whichever occurs last
• Has urine protein ≥1 g/24 hours and has any of the following: (a) hypoxia defined as a pulse oximeter reading <92% at rest, or (b) requires intermittent supplemental oxygen, or (c) requires chronic supplemental oxygen
• Has clinically significant cardiovascular disease within 12 months from the first dose of study intervention administration
• Has had major surgery within 3 weeks before first dose of study interventions
• Has a history of lung disease
• Has a history of inflammatory bowel disease
• Has preexisting gastrointestinal (GI) or non-GI fistula
• Has malabsorption due to prior GI surgery or disease
• Has previously received treatment with a combination of pembrolizumab plus lenvatinib
• Has received prior treatment with belzutifan
• Has received prior radiotherapy within 2 weeks of start of study intervention
• Has received a live or live attenuated vaccine within 30 days before the first dose of study intervention; killed vaccines are allowed
• Has received more than 4 previous systemic anticancer treatment regimens
• Has a diagnosis of immunodeficiency or is receiving any form of immunosuppressive therapy within 7 days prior to the first dose of study intervention
• Has known additional malignancy that is progressing or has required active treatment within the past 3 years
• Has known central nervous system (CNS) metastases and/or carcinomatous meningitis
• Has an active autoimmune disease that has required systemic treatment in the past 2 years; replacement therapy is not considered a form of systemic treatment and is allowed
• Has an active infection requiring systemic therapy
• Has a known history of human immunodeficiency virus (HIV) infection
• Has a known history of Hepatitis B
• Has had an allogenic tissue/solid organ transplant

• Patients with locally advanced or metastatic renal cell carcinoma.
• Patients scheduled to undergo anti-angiogenic treatment or immunotherapy
• Eastern Cooperative Oncology Group (ECOG) Status 0, 1 and 2.
• Women of child-bearing potential must agree to undergo a urine pregnancy screening per standard Radiology departmental protocol, in place to prevent imaging of pregnant patients. A female of child-bearing potential is any woman (regardless of sexual orientation, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria: 1) Has not undergone a hysterectomy or bilateral oophorectomy; or 2) Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months).
• Ability to understand and the willingness to sign a written informed consent.
• Subjects may not be receiving any other anti-angiogenic agents, at the time of enrollment.
• Subjects must not be pregnant since pregnancy is a contraindication to administration of gadolinium-based contrast agents.
• Any contraindication to MRI per Radiology Department's routine protocol, e.g. MRI-incompatible objects, including but not limited to medical devices (e.g. pacemakers, automated implantable cardioverter defibrillators, etc.) and other foreign bodies.
• Known severe allergic reaction to Gadolinium-based contrast agents.
• Patients with sickle cell disease and patients with other hemolytic anemias (low red blood count in body).
• Patients with uncontrollable claustrophobia, severe lower back pain, and uncontrollable tremors, to the point that it would render them unable to tolerate an MRI study.

• histologically or cytologically confirmed unresectable advanced or metastatic nccRCC, including but not limited to:
• Papillary RCC, any type
• Unclassified RCC
• Translocation RCC
• Chromophobe RCC
• Collecting duct RCC
• Medullary RCC
• Renal cell carcinoma with 80% or more sarcomatoid features on primary nephrectomy specimen or a biopsy
• Other nccRCC histologies
• Measurable disease as per RECIST 1.1. See Section 11 for the evaluation of measurable disease.
• Age ≥ 18 years
• ECOG performance status ≤1 (Karnofsky ≥70%, see Appendix A)
• Participants must undergo fresh tumor biopsy after registration but prior to the start of treatment unless medically unsafe or not feasible. If a fresh tumor biopsy is not medically safe or not feasible, confirmation of the availability of archival tumor tissue is required. For archival tissue, a recommended minimum of 20 unstained slides should be obtained.
• Normal organ and marrow function as defined below:
• absolute neutrophil count ≥1,500/mcL
• platelets ≥100,000/mcL
• hemoglobin ≥9g/dL (transfusions allowed)
• total bilirubin ≤2.0 x institutional upper limit of normal with the following exception: patients with known Gilbert disease should have a serum bilirubin ≤ 3 x ULN
• AST(SGOT)/ALT(SGPT) ≤2.5 × institutional upper limit of normal with the following exception: patients with known liver metastases should have AST and ALT ≤ 5 x ULN
• creatinine clearance ≥30 mL/min/1.73 m2 according to the Cockcroft-Gault equation.
• Normal coagulation INR ≤ 1.5
• Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for 5 months after the duration of study participation. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 7 months after completion of cabozantinib, nivolumab or ipilimumab administration.
• Ability to understand and willingness to sign a written informed consent document
•Patients could be untreated or have received prior lines of therapies. Patients who receive prior therapy may receive only one VEGF based therapy. A combination therapy (e.g. lenvatinib+everolimus) is considered 1 line of therapy.
• Previous therapy with CD137 agonists and immune checkpoint inhibitors, including but not limited to inhibitors of the PD-1/PD-L1 and/or CTLA-4 axes. Previous treatment with IFNα or IL-2 is allowed if received > 4 weeks from enrollment.
• Treatment with small molecule tyrosine kinase inhibitors within 2 weeks of enrollment, or any other anticancer agent within 4 weeks of enrollment.
• Prior therapy with cabozantinib
• Patients receiving any other therapeutic investigational agents.
• Treatment with hydroxychloroquine within two weeks of treatment start.
• Radiotherapy for nccRCC within 14 days of first study treatment with the exception of a single fraction of radiation administered for palliation of symptoms.
• Untreated brain metastases. Patients might be included if they underwent radiation therapy or surgery at least 4 weeks prior enrollment. Stability of the central nervous system disease should be confirmed by brain MRI or CT-scan or as determined by treating investigator. Patients should not be receiving prednisone dose >10 mg/d at C1D1.
• Other malignancy diagnosed within 2 years of first study treatment unless negligible risk of metastases or death (included but not limited to carcinoma in situ of the cervix, basal or squamous cell skin cancer, localized prostate cancer, ductal carcinoma in situ of the breast, non-muscle invasive urothelial carcinoma, or other malignancy not deemed to impact patients 5-year life expectancy).
• Significant cardiovascular disorders including:
• Significant cardiovascular disease including dyspnea of New York Heart Association (NYHA) class II or greater, myocardial infarction within the previous 3 months of first study treatment, unstable arrhythmias, unstable angina. Patients with known coronary artery disease or congestive heart failure not meeting the above criteria, or left ventricular ejection fraction < 50%, must be on a stable and optimized in the opinion of the treating physician, in consultation with a cardiologist when appropriate.
• Uncontrolled hypertension (defined as systolic blood pressure > 150 mmHg and/or diastolic blood pressure > 100 mmHg). Anti-hypertensive therapy is allowed.
• Personal history of hypertensive crisis or hypertensive encephalopathy within the previous 3 months of registration.
• Personal history of stroke or transient ischemic attack within 3 months of registration.
• Significant vascular disease, such as but not limited to aortic aneurysm requiring surgical repair or recent peripheral arterial thrombosis, within 6 months of registration.
• Corrected QT interval calculated by the Fridericia formula (QTcF) > 500 ms per electrocardiogram (ECG). Furthermore, subjects with a history of additional risk factors for torsades de pointes (eg, long QT syndrome) are also excluded.
• Known history of severe allergic reactions attributed to compounds of similar chemical or biologic composition human antibodies, or known hypersensitivity to any component of cabozantinib, nivolumab or ipilimumab products.
• Systemic immunosuppressive medications including but not limited to: Corticosteroids at a dose > 10mg equivalent prednisone daily, cyclosporin, azathioprine, methotrexate, thalidomide, anti-tumor necrosis factor (TNF) agents, hydroxychloroquine, within 2 weeks of first study dose.
• Patients who have received acute, low-dose systemic immunosuppressant medications may be enrolled.
• Patients with adrenal insufficiency on physiologic replacement doses of steroids may be enrolled.
• The use of inhaled, topical, intraocular, or intraarticular corticosteroids or mineralocorticoids are allowed
• Prior allogenic stem cell or solid organ transplant.
• Personal history of autoimmune disease including: myasthenia gravis, myositis, autoimmune hepatitis, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, vascular thrombosis associated with anti-phospholipid syndrome, Wegner's granulomatosis, Sjogren's syndrome, Guillain-Barre syndrome, multiple sclerosis, type I diabetes mellitus, vasculitis, or glomerulonephritis. Patients with a history of autoimmune-related hypothyroidism on thyroid replacement hormone, or those with autoimmune dermatologic conditions not requiring the use of prednisone > 10 mg or equivalent are eligible.
• History of idiopathic pulmonary fibrosis, organized pneumonia, or evidence of active pneumonitis on screening imaging CT of the chest. History of radiation pneumonitis in the radiation field is permitted.
• History of following infectious diseases:
• Active or chronic hepatitis B (defined as having a positive hepatitis B surface antigen [HBsAg] test at screening).
• Active hepatitis C infection. Patients with positive hepatitis C antibody test are eligible if PCR is negative for hepatitis C viral DNA.
• Infection requiring therapeutic oral or IV anti-microbials within 2 weeks of first study treatment. Patients receiving routine antimicrobial prophylaxis for dental procedures are eligible.
• Known positive test for HIV.
• Administration of a live, attenuated vaccine within 3 weeks for first study treatment.
• Bleeding diathesis, or significant coagulopathy in the absence of therapeutic anticoagulation.
• Use of strong inhibitors and inducers of CYP3A4
• Significant bleeding, including but not limited to hematemesis, hematuria, hemoptysis of > 0.5 teaspoon (2.5 mL), within 3 months before registration.
• Invasion of major pulmonary blood vessels. A discussion with PI may be needed if invading lesions are suspected.
• Concomitant use of dipyramidole, ticlopidine, clopidogrel, cilostazol is excluded. Aspirin (≤ 325 mg per day) is allowed. Prophylactic anticoagulation with oral or parenteral anticoagulants for the patency of venous access devices or other indications is allowed. Therapeutic use of low-molecular weight heparin (such as enoxaparin) and subcutaneous or oral Factor Xa inhibitors are allowed. Use of warfarin is prohibited.
• Significant GI conditions at risk of perforation or bleeding, including but not limited to:
• Active GI obstruction or requirement of routine parenteral nutrition or tube feedings.
• Personal history of abdominal or tracheoesophageal fistula or GI perforation within 6 months of registration.
• Evidence of abdominal free air not explained by paracentesis or recent surgical procedure.
• Serious, non-healing or dehiscing wound or active ulcer.
• Major surgical procedure to include major dental, oral or maxillofacial procedures within 14 days of first study treatment.
• Proteinuria as demonstrated by > 1.5 gram of protein in a 24-hour urine collection. All patients with ≥ 2+ protein on urinalysis must undergo 24-hour urine collection for protein.
• Unable to swallow pills.
• Malabsorption syndrome.
• Inability to receive IV medications
• Pregnant or lactating women.

• Patients with suspected primary RCC with planned surgery (cohort 1) or patients with tissue-confirmed metastatic ccRCC with a site accessible for biopsy (cohort 2). (In standard clinical practice, biopsy is not routinely performed in patients who will be having surgery).
• Ability to understand and the willingness to sign a written informed consent that includes study interventions (PET/CT and, if cohort 2, mandatory biopsy).
• Ability to lie still for a 30- to 60-minute PET/CT scan.
• One of the following: 1. Cohort 1. Patients with suspected RCC planned for surgery. 2. Cohort 2. Patients with metastatic ccRCC.
• Women of child-bearing potential must agree to undergo and have documented a negative pregnancy test on the day of [18F]PT2385 administration. A female of child-bearing potential is any woman (regardless of sexual orientation, having undergone a tubal ligation, or celibate by choice) who meets the following criteria: 1. Has not undergone a hysterectomy or bilateral oophorectomy; or 2. Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months).
• Uncontrolled severe and irreversible intercurrent illness or psychiatric illness/social situations that would limit compliance with study requirements.
• Subjects must not be pregnant or nursing due to the potential for congenital abnormalities and the potential of this regimen to harm nursing infants.
• Claustrophobia or other contraindications to PET/CT.
• Subjects must not weigh more than the maximum weight limit for the table for the PET/CT scanner where the study is being performed (>200 kilograms or 440 pounds).
• For cohort 2 patients, lack of suitable sites for mandatory biopsy. For example, patients with metastatic disease restricted to the lungs that would require percutaneous biopsies with associated risk of bleeding and pneumothorax will be excluded.

Inclusion Criteria-Part A: Subject must meet all of the following applicable inclusion criteria to participate in this study:
• Patients must have histologically confirmed advanced RCC (any histology). Collecting duct tumors and tumors originating from the renal pelvis or upper urinary tract are considered of urothelial origin and are excluded from this protocol.
• Patients must have at least one measurable site of disease, per RECIST 1.1, that has not been previously irradiated. If the patient has had previous radiation to the marker lesion(s), there must be evidence of progression since the radiation.
• Archival tissue of a metastatic lesion obtained within 1 year prior to study registration (within 4 weeks preferred) and tumor tissue from nephrectomy is required if available. In addition to archival tissue of a metastatic lesion and nephrectomy, patients must have at least one site of disease (not including bone metastases) accessible for biopsy. If biopsy/resection of a new lesion or primary tumor and slow freezing of fresh tissue for single cell RNAseq study (as specified in the CLM) is not feasible, the subject is not eligible for the study. All biopsies must be core needle or excisional. Fine needle aspirate is not acceptable. NOTE: The tissue collected from a surgical resection or multiple core biopsies of either a metastatic lesion or primary tumor for the slow freezing of fresh tissue after the patient has signed consent for the study could also be used for collecting the FFPE specimens.
• ECOG performance status 0-2.
• Age ≥ 18 years.
• Have signed the current approved informed consent form.
• Patients must have adequate organ function within 14 days prior to study entry as evidenced by screening laboratory values that must meet the following criteria:
• Hematological:
• White blood cell (WBC) ≥ 2000/µL
• Absolute Neutrophil Count (ANC) ≥ 1500/μL
• Platelets (Plt) ≥ 100 x103/μL
• Hemoglobin (Hgb) > 9.0 g/dL (with or without transfusion)
• Renal:
• Serum Creatinine ≤ 1.5 x ULN; if creatinine > 1.5, subject must demonstrate CrCl as outlined below.
• Calculated creatinine clearance ≥ 40 mL/min using Cockcroft-Gault formula
• Hepatic:
• Bilirubin ≤ 1.5× upper limit of normal (ULN); Except subjects with Gilbert Syndrome, who can have total bilirubin < 3.0 mg/dL
• Aspartate aminotransferase (AST) ≤ 3 × ULN
• Alanine aminotransferase (ALT) ≤ 3 × ULN
• Patients should not have received prior systemic therapy for metastatic RCC. Prior radiotherapy must have been completed at least 2 weeks prior to the administration of study drug. Patients must be 2 weeks from prior major surgery and 1 week from pre-treatment biopsy. Prior systemic adjuvant therapy (excluding with PD1 or CTLA4 pathway blockers) is allowed if treatment completed > 12 months previously.
• Women of childbearing potential (WOCBP) must use appropriate method(s) of contraception. WOCBP should use an adequate method to avoid pregnancy for 5 months after the last dose of study drug. NOTE: Contraception is not required for male participants.
• Women of childbearing potential must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of HCG) during screening for registration purposes. This pregnancy test should be repeated within 24 hours prior to the start of nivolumab. NOTE: "Women of childbearing potential" is defined as any female who has experienced menarche and who has not undergone surgical sterilization (hysterectomy or bilateral oophorectomy) or who is not postmenopausal. Menopause is defined clinically as 12 months of amenorrhea in a woman over 45 in the absence of other biological or physiological causes. In addition, women under the age of 55 must have a documented serum follicle stimulating hormone (FSH) level less than 40 mIU/ml.
• Women must not be breastfeeding.
• Be willing and able to comply with this protocol.
• Patients are excluded if they have active brain metastases or leptomeningeal metastases. Subjects with brain metastases are eligible if metastases have been treated and there is no magnetic resonance imaging (MRI) evidence of progression for 2 weeks of more after treatment is complete and within 28 days prior to the first dose of nivolumab administration. There must also be no requirement for immunosuppressive doses of systemic corticosteroids (> 10 mg/day prednisone equivalents) for at least 2 weeks prior to study drug administration.
• Patients with controlled brain metastases are allowed on protocol if they had solitary brain metastases that was surgically resected without recurrence or treated with SRS without progression x 4 weeks.
• Patients should be excluded if they have an active, known or suspected autoimmune disease. Subjects are permitted to enroll if they have vitiligo, type I diabetes mellitus, residual hypothyroidism due to autoimmune condition only requiring hormone replacement, psoriasis not requiring systemic treatment, or conditions not expected to recur in the absence of an external trigger.
• Patients should be excluded if they have a condition requiring systemic treatment with either corticosteroids (> 10 mg daily prednisone equivalents) or other immunosuppressive medications within 14 days of study drug administration. Inhaled or topical steroids and adrenal replacement doses > 10 mg daily prednisone equivalents are permitted in the absence of active autoimmune disease.
• As there is potential for hepatic toxicity with nivolumab or nivolumab/ipilimumab combinations, drugs with a predisposition to hepatoxicity should be used with caution in patients treated with nivolumab-containing regimen
• Active infection requiring systemic therapy
• Has any other medical or personal condition that, in the opinion of the site investigator, may potentially compromise the safety or compliance of the patient, or may preclude the patient's successful completion of the clinical trial
• Patients should be excluded if they are positive test for hepatitis B virus surface antigen (HBV sAg) or hepatitis C virus ribonucleic acid (HCV antibody) indicating acute or chronic infection
• Patients should be excluded if they have known history of testing positive for human immunodeficiency virus (HIV) or known acquired immunodeficiency syndrome (AIDS)
• Allergies and Adverse Drug Reaction
• History of allergy to study drug components
• History of severe hypersensitivity reaction to any monoclonal antibody
• Known additional malignancies within the past 3 years (excluding basal of squamous cell skin cancers, CIS or localized prostate cancer that has been treated or is being observed) Inclusion/Exclusion Criteria- Part B
• Must meet eligibility criteria for initiation of Part A with the exception of being allowed to have prior nivolumab in Part A of this protocol
• Must have evidence of either RECIST 1.1 defined Disease Progression or Stable Disease 1 year after initiating nivolumab therapy
• Tumor biopsy prior to combination treatment is mandatory. If a biopsy/resection of a new lesion or primary tumor and slow freezing of fresh tissue for single cell RNAseq study (as specified in the CLM) is not feasible, the subject is not eligible for the study. All biopsies must be core needle or excisional. Fine needle aspirate is not acceptable.
• Must not have had a Grade ≥ 3 irAE on nivolumab monotherapy
• Must not have untreated brain metastases
• Must not have had major surgery or radiation therapy within 14 days of starting study treatment
• Must not have active autoimmune disease
• Must not have a concurrent medical condition requiring use of systemic corticosteroids with prednisone >10 mg per day
• Must not have had prior systemic therapy for Stage IV RCC (except for nivolumab as part of part A of this protocol)
• Prior solid organ or stem cell transplant

• Unresectable, locally advanced or metastatic clear cell renal cell carcinoma (RCC).
• Disease progression on or after an anti-programmed cell death-1/ligand 1 (PD-1/L1) therapy as either first or second-line treatment for locally advanced/metastatic RCC or as adjuvant treatment with progression on or within 6 months of last dose.
• Measurable disease per RECIST 1.1 criteria as assessed by local study investigator.
• Karnofsky performance status (KPS) score of at least 70% assessed within 10 days before randomization.
• Received no more than 2 prior systemic regimens.
• Received only 1 prior antiPD-1/L1 therapy for adjuvant or locally advanced/metastatic RCC.
• A male participant is eligible to participate if he is abstinent from heterosexual intercourse or agrees to use contraception during the intervention period and for at least 7 days after the last dose of belzutifan or lenvatinib in the belzutifan+lenvatinib arm, whichever occurs last, and 23 days after the last dose of cabozantinib.
• A female participant is eligible to participate if she is not pregnant, not breastfeeding, and at least 1 of the following conditions applies: Not a woman of childbearing potential (WOCBP) or a WOCBP who agrees to follow the contraceptive guidance during the intervention period and for at least 30 days after the last dose of study intervention in the belzutifan+ lenvatinib arm, or 120 days after the last dose of study intervention in the cabozantinib arm.
• Adequately controlled blood pressure.
• Adequate organ function.
• A pulse oximeter reading <92% at rest, requires intermittent supplemental oxygen, or requires chronic supplemental oxygen.
• Known additional malignancy that is progressing or has required active treatment within the past 3 years except for basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or carcinoma in situ (eg, breast carcinoma, cervical cancer in situ) that have undergone potentially curative therapy.
• Known central nervous system (CNS) metastases and/or carcinomatous meningitis.
• Clinically significant cardiac disease within 6 months of first dose of study intervention.
• Prolongation of QTc interval to >480 ms.
• Symptomatic pleural effusion (e.g.,cough, dyspnea, pleuritic chest pain) that is not clinically stable.
• Pre-existing ≥Grade 3 gastrointestinal or nongastrointestinal fistula.
• Moderate to severe hepatic impairment.
• History of significant bleeding within 3 months before randomization.
• History of solid organ transplantation.
• Known psychiatric or substance abuse disorder that would interfere with cooperation with the requirements of the study.
• Unable to swallow orally administered medication or has a gastrointestinal disorder affecting absorption (e.g., gastrectomy, partial bowel obstruction, malabsorption).
• Known hypersensitivity or allergy to the active pharmaceutical ingredients or any component of the study intervention formulations.
• Received colony-stimulating factors [eg, granulocyte colony-stimulating factor (G-CSF), granulocyte macrophage colony-stimulating factor (GMCSF) or recombinant erythropoietin (EPO)] within 28 days before randomization.
• Prior treatment with belzutifan or another hypoxia-inducible factor (HIF)-2α inhibitor.
• Prior treatment with lenvatinib.
• Prior treatment with cabozantinib.
• Currently participating in a study of an investigational agent or using an investigational device.
• Active infection requiring systemic therapy.
• History of human immunodeficiency virus (HIV) infection.
• History of hepatitis B or known active hepatitis C infection.

• STEP 1 REGISTRATION: Participants must have a histologically proven diagnosis of clear cell or non-clear cell renal cell carcinoma. Participants with collecting duct carcinoma histology are not eligible. Participants with multifocal or bilateral tumors are eligible
• STEP 1 REGISTRATION: Participants must have primary tumor in place
• STEP 1 REGISTRATION: Participants must have the following scans performed, showing clinical evidence of measurable or non-measurable metastatic disease:
• Computed tomography (CT) scan of the chest (can be performed without contrast if CT contrast cannot be given)
• CT of abdomen and pelvis with contrast OR magnetic resonance imaging (MRI) of the abdomen and pelvis with or without contrast Scans must be performed within the following timeframes:
• Treatment naive participants must have scans documenting metastatic disease completed within 90 days prior to study registration
• Previously treated participants must have scans documenting metastatic disease completed within 90 days prior to first dose of systemic treatment
• STEP 1 REGISTRATION: Participants with symptomatic metastases may have received palliative radiotherapy or receive palliative radiotherapy after registration
• STEP 1 REGISTRATION: Participants must have no clear contraindications to nephrectomy
• STEP 1 REGISTRATION: Participants must be offered the opportunity to participate in specimen bank. With participant consent, specimens must be collected and submitted via the Southwest Oncology Group (SWOG) Specimen Tracking System
• STEP 1 REGISTRATION: Participants must be informed of the investigational nature of this study and must sign and give informed consent in accordance with institutional and federal guidelines
• STEP 1 REGISTRATION: As part of the Oncology Patient Enrollment Network (OPEN) registration process the treating institution's identity is provided in order to ensure that the current (within 365 days) date of institutional review board approval for this study has been entered in the system
• STEP 2 REGISTRATION: Participants must have at least one of the following scans performed 12 weeks (+/- 2 weeks) after starting pre-randomization treatment
• CT scan of the chest (can be performed without contrast if CT contrast cannot be given)
• CT of abdomen and pelvis with contrast OR MRI of the abdomen and pelvis with or without contrast Scans must be performed within 28 days prior to randomization. Response should be assessed by comparing with a CT or MRI of the chest, abdomen and pelvis obtained prior to starting pre-randomization treatment. Participants with complete response in all metastatic sites are not eligible to randomize to Step 2 • STEP 2 REGISTRATION: Participants must have one of the following objective statuses after 12 weeks of pre-randomization treatment
• Stable disease
• Partial response
• The treating investigator believes the patient is deriving clinical benefit from systemic therapy AND have Zubrod performance status 0-1
• STEP 2 REGISTRATION: Participants must plan to continue the immune-based therapy received during pre-randomization treatment
• STEP 2 REGISTRATION: Participants must be randomized on or between the 11th and 14th week of protocol-directed pre-randomization treatment therapy
• STEP 2 REGISTRATION: Participants must have received at least one of the minimum amounts of immunotherapy:
• 2 infusions of nivolumab + 1 infusion of ipilimumab
• 2 infusions of pembrolizumab
• 2 infusions of avelumab
• STEP 2 REGISTRATION: Participants must have a planned surgery date within 42 days of randomization
• STEP 2 REGISTRATION: Participants must be a surgical candidate as determined by study urologist. The urology consult should be done within 42 days prior to randomization
• STEP 2 REGISTRATION: Participants must have a complete physical examination and medical history within 28 days prior to randomization
• STEP 2 REGISTRATION: Participants must have a Zubrod performance status of 0-1 within 28 days prior to randomization
• STEP 2 REGISTRATION: Total bilirubin =< institutional upper limit of normal (ULN) (within 28 days prior to randomization)
• STEP 2 REGISTRATION: Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) =< 3 x institutional upper limit of normal (ULN) (within 28 days prior to randomization)
• STEP 2 REGISTRATION: Serum creatinine =< 1.5 x the institutional upper limit of normal (IULN) OR measured OR calculated creatinine clearance >= 50 mL/min using the Cockcroft-Gault Formula) (must have been drawn and processed within 28 days prior to randomization)
• STEP 1 REGISTRATION: Participants must not have known active brain metastases. Participants with previously treated brain metastases are eligible if participant has no neurologic signs or symptoms suggestive of brain metastasis. Brain imaging studies are not required. If brain imaging studies are performed, they must be negative for disease
• STEP 1 REGISTRATION: Participants must not have received the following prior treatment of metastatic renal cell carcinoma:
• Treatment naive participants must not have received any prior lines of systemic therapy for metastatic renal cell carcinoma beyond the line intended as part of protocol therapy
• Previously treated participants must not have received any systemic therapy for metastatic renal cell carcinoma beyond the one regimen received off protocol as specified in Step 1 pre-randomization treatment
• STEP 1 REGISTRATION: Participants must not have received more than the following amounts protocol-directed pre-randomization treatment:
• Treatment naive participants must not have received any pre-randomization treatment.
• Previously treated participants must not be planning to receive any additional treatment prior to Step 2 randomization, and must not have received more than the following amounts of pre-randomization treatment:
• 4 infusions of nivolumab
• 4 infusions of ipilimumab
• 4 infusions of pembrolizumab
• 7 infusions of avelumab
• STEP 1 REGISTRATION: Participants must not have received immunotherapy for any cancer within the following timeframes:
• Treatment naive participants must not have received any immunotherapy within a year of registration
• Previously treated participants must not have received any other immunotherapy within a year of the start of off protocol specified pre-randomization treatment
• STEP 1 REGISTRATION: Participants must not have a solitary kidney and not have a transplanted kidney
• STEP 1 REGISTRATION: No other prior malignancy is allowed except for the following: adequately treated basal cell or squamous cell skin cancer, any in situ or T1 cancer, adequately treated stage I or II cancer from which the participant is currently in complete remission, or any other cancer from which the participant has been disease free for at least two years
• STEP 1 REGISTRATION: Participants must not have been previously diagnosed with a medical condition that makes them ineligible for immune based combination therapy or nephrectomy
• STEP 2 REGISTRATION: Participants must not show progression in the primary tumor. Participants who are considered to have pseudo progression are allowed
• STEP 2 REGISTRATION: Participants must not have known active brain metastases. Participants with previously treated brain metastases are eligible if participant has no neurologic signs or symptoms suggestive of brain metastasis. Brain imaging studies are not required. If brain imaging studies are performed, they must be negative for disease
• STEP 2 REGISTRATION: No other prior malignancy is allowed except for the following: adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer, adequately treated stage I or II cancer from which the participant is currently in complete remission, or any other cancer from which the participant has been disease free for two years

• Documented histologic or cytologic diagnosis of renal cell cancer (RCC). All subtypes of RCC are eligible including but not limited to clear cell, papillary, chromophobe, translocation, collecting duct carcinoma, medullary carcinoma, and unclassified categories. Enrollment of non-clear cell patients will be limited to 20% of the total sample size (~ 42 patients). Once this goal is met, accrual of non-clear cell patients will be discontinued (a notice will be sent out 2 weeks in advance). Sarcomatoid and rhabdoid differentiation are allowed
• Presence of at least 1 metastatic bone lesion not treated with prior radiation is required.
• The presence of bone metastases can be detected by computed tomography (CT), magnetic resonance imaging (MRI), Tc-99m bone scan or positron emission tomography (PET) (fludeoxyglucose F-18 [FDG] or sodium fluoride [NaF]) imaging. Patients with non-measurable bone-only disease are allowed. Patients may have received prior radiation therapy for bone metastases or other external radiation >= 7 days prior to registration, as long as they still have at least 1 metastatic bone lesion not treated with radiation. Patients with visceral metastases are allowed, as long as they have at least one untreated bone metastases
• No prior treatment with cabozantinib
• No treatment with any type of small molecular kinase inhibitor (including investigational kinase inhibitors) within 2 weeks or 5 half-lives (whichever is shorter) of registration or receipt of any anti-cancer therapy (including investigational therapy, monoclonal antibodies, cytokine therapy) within 3 weeks of registration
• No prior hemibody external radiotherapy
• No prior therapy with radium-223 dichloride or systemic radiotherapy (such as samarium, strontium)
• No major surgery within 6 weeks of randomization. Procedures such as thoracentesis, paracentesis, percutaneous biopsy, Moh's or other topical skin surgery, Lasik eye surgery are not considered major surgery. Patients who have had a nephrectomy may be registered >= 3 weeks after surgery, providing there are no wound-healing complications. Subjects with clinically relevant ongoing complications from prior surgery are not eligible
• Recovery to baseline or =< grade 1 CTCAE version 5.0 from toxicity related to any prior treatment, unless adverse events are clinically nonsignificant and/or stable on supportive therapy
• The use of osteoclast targeted therapy including either bisphosphonates or denosumab is mandated on this study except in patients with contraindications as determined by the treating investigator, including:
• Hypocalcemia
• Hypophosphatemia
• Renal impairment including those with a glomerular filtration rate (GFR) < 35 mL/min using the Cockcroft-Gault equation or acute renal impairment
• Hypersensitivity to drug formulation
• Dental condition or need for dental intervention that per the investigator would increase the risk of osteonecrosis of jaw (ONJ).
• Use of osteoclast targeted therapy or reason against use needs to be recorded in the electronic case report form (eCRF). Additionally, reason for discontinuation of osteoclast targeted therapy need to be appropriately documented in the eCRF
• Not pregnant and not nursing, because this study involves an investigational agent whose genotoxic, mutagenic and teratogenic effects on the developing fetus and newborn are unknown.
• Therefore, for women of childbearing potential only, a negative urine pregnancy test done =< 28 days prior to registration is required. A female of childbearing potential is a sexually mature female who: 1) has not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months)
• Karnofsky performance status >= 60%
• No brain metastases or cranial epidural disease unless adequately treated with radiotherapy, radiosurgery, or surgery and stable for at least 4 weeks prior to registration as documented by MRI or CT imaging or deemed stable by clinical investigator. Treated brain metastases are defined as having no ongoing requirement for steroids and no evidence of progression or hemorrhage after treatment for at least 4 weeks prior to registration as documented by MRI or CT imaging or deemed stable by clinical investigator
• No imminent or established spinal cord compression based on clinical symptoms and/or imaging. In patients with untreated imminent or established spinal cord compression, treatment with standard of care as clinically indicated should be completed at least 2 weeks before registration
• No imminent or impending pathologic fracture based on clinical symptoms and/or imaging. In patients with untreated imminent or impending pathologic fracture, treatment with standard of care as clinically indicated should be completed at least 2 weeks before registration
• No significant, uncontrolled intercurrent or recent illness, including but not limited to the following conditions:
• Cardiovascular disorders: Symptomatic congestive heart failure, unstable angina pectoris, serious cardiac arrhythmia; uncontrolled hypertension defined as sustained blood pressure > 150 mm Hg systolic or > 100 mm Hg diastolic despite optimal antihypertensive treatment; stroke (including transient ischemic attack), myocardial infarction, or other ischemic event, within 6 months before randomization; thromboembolic event (e.g., deep venous thrombosis, pulmonary embolism) within 1 month before randomization
• Gastrointestinal disorders: Disorders associated with a high risk of perforation or fistula formation: active inflammatory bowel disease, active diverticulitis, active cholecystitis, active symptomatic cholangitis or active appendicitis, active acute pancreatitis or active acute obstruction of the pancreatic or biliary duct, or active gastric outlet obstruction; abdominal fistula, gastrointestinal perforation, bowel obstruction, or intra-abdominal abscess within 3 months before randomization. Note: Complete healing of an intra-abdominal abscess must be confirmed before randomization
• No clinically significant hematuria, hematemesis, or hemoptysis, or other history of significant bleeding (e.g., pulmonary hemorrhage) within 3 months before randomization
• No lesions invading major pulmonary blood vessels
• No other clinically significant disorders:
• Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy (with no medications prohibited by this protocol [e.g. drug-drug interactions]) with undetectable viral load within 6 months are eligible for this trial
• For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy (with no medications prohibited by this protocol [e.g. drug-drug interactions]), if indicated
• Patients with a history of hepatitis C virus (HCV) infection must have been treated and cured. For patients with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load (with no medications prohibited by this protocol [e.g. drug-drug interactions])
• No serious non-healing wound or ulcer
• No malabsorption syndrome
• No uncompensated/symptomatic hypothyroidism
• No moderate to severe hepatic impairment (Child-Pugh B or C)
• No requirements for hemodialysis or peritoneal dialysis
• No history of solid organ transplantation
• No chronic concomitant treatment with strong CYP3A4 inducers or inhibitors. Because the list of these agents is constantly changing, it is important to regularly consult a frequently updated medical reference. Patients may not have received a strong CYP3A4 inducer within 12 days prior to registration nor a strong CYP3A4 inhibitor within 7 days prior to registration
• No concomitant anticoagulation with coumarin agents (e.g., warfarin), direct thrombin inhibitors (e.g., dabigatran), direct factor Xa inhibitor betrixaban, or platelet inhibitors (e.g., clopidogrel). Allowed anticoagulants include:
• Prophylactic use of low-dose aspirin for cardio-protection (per local applicable guidelines) and low-dose low molecular weight heparins (LMWH).
• Therapeutic doses of LMWH or anticoagulation with direct factor Xa inhibitors rivaroxaban, edoxaban, or apixaban in subjects without known brain metastases who are on a stable dose of the anticoagulant for at least 1 week before first dose of study treatment without clinically significant hemorrhagic complications from the anticoagulation regimen or the tumor.
• Absolute neutrophil count (ANC) >= 1,500/mm^3
• Platelet count >= 100,000/mm^3
• Hemoglobin >= 9 g/dl (transfusions allowed)
• Calculated (calc.) creatinine clearance >= 30 mL/min using the Cockcroft-Gault equation
• Total bilirubin =< 1.5 x upper limit of normal (ULN), for patients with Gilberts disease =< 3.0 x ULN
• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) =< 3.0 x ULN
• Urine protein to creatinine (UPC) ratio =< 2 mg/mg OR 24-hr urine protein < 2 g

• Patients with newly diagnosed stages 2
•4 diffuse anaplastic Wilms tumor must be enrolled on AREN03B2 and have risk assignment or final pathology classification (if at delayed nephrectomy) results available prior to enrollment on AREN1921. Enrollment on AREN03B2 is not applicable for patients with relapsed favorable histology Wilms tumor
• Patients with the following diagnoses are eligible for this study:
• Newly diagnosed stages 2
•4 diffuse anaplastic Wilms tumor as confirmed by central review
• Favorable histology Wilms tumor at first relapse. Relapsed FHWT patients must have previously achieved remission for their initial FHWT diagnosis to be eligible for this study. The relapse risk groups are defined as follows, regardless of radiation therapy:
• Standard-Risk relapse: Patients who received two chemotherapy agents for frontline therapy; primarily actinomycin D and vincristine
• High-Risk relapse: Patients who received three chemotherapy agents for frontline therapy; primarily vincristine, actinomycin D and doxorubicin or vincristine, actinomycin D and irinotecan
• Very High-Risk relapse: Patients who received four or more chemotherapy agents as part of initial therapy; primarily Regimen M or its variations
• Patients with newly diagnosed DAWT must have had histologic verification of the malignancy. For relapsed FHWT patients, biopsy to prove recurrence is encouraged, but not required
• Note: for relapsed FHWT patients, an institutional pathology report confirming favorable histology Wilms tumor (from relapse, if available, or from original diagnosis) must be available for upload prior to initiation of protocol therapy
• Patients with newly diagnosed stages 2
•4 diffuse anaplastic Wilms tumor must be enrolled on AREN1921 within 2 weeks of the first tumor-directed surgery or biopsy procedure (surgery/biopsy is day 0), except for patients who received prior therapy for presumed favorable histology Wilms tumor, later confirmed to have diffuse anaplastic Wilms tumor at subsequent review
• Patients with newly diagnosed DAWT who undergo upfront nephrectomy must have at least 1 lymph node sampled prior to study enrollment
• Patients must have a performance status corresponding to Eastern Cooperative Oncology Group (ECOG) scores of 0, 1 or 2. Use Karnofsky for patients > 16 years of age and Lansky for patients =< 16 years of age
• Patients must have a life expectancy of >= 8 weeks
• Diffuse Anaplastic Wilms Tumor: Patients with diffuse anaplastic histology must have had no prior systemic therapy, except in the following situations:
• Patients with diffuse anaplastic Wilms tumor who received no more than 12 weeks of pre nephrectomy chemotherapy for what was originally presumed to be favorable histology Wilms tumor, subsequently confirmed to be diffuse anaplastic Wilms tumor at delayed nephrectomy.
• Patients with diffuse anaplastic Wilms tumor who received no more than 6 weeks of chemotherapy following upfront nephrectomy or biopsy for presumed favorable histology Wilms tumor based on institutional review, but subsequently corrected to diffuse anaplastic Wilms tumor based on the AREN03B2 initial risk assignment results.
• Treatment consisting of vincristine/doxorubicin/ cyclophosphamide initiated on an emergent basis and within allowed timing as described
• Patients who received prior therapy for presumed favorable histology Wilms tumor, later identified to have diffuse anaplastic Wilms tumor as per above, must begin study treatment starting at cycle 3 (week 7) of regimen UH 3. For treatment details specific to this group of patients. Patients who received emergency radiation to preserve organ function are eligible as noted
• Relapsed Favorable Histology Wilms Tumor: Patients must not have received prior chemotherapy for their relapsed favorable histology Wilms tumor diagnosis. In addition, patients must have fully recovered from the acute toxic effects of all prior chemotherapy, immunotherapy, or radiotherapy prior to entering this study
• Myelosuppressive chemotherapy: Must not have received within 2 weeks of entry onto this study
• Radiation therapy (RT): >= 2 weeks (wks) must have elapsed for local palliative RT (small port); >= 6 months must have elapsed if prior craniospinal RT or if >= 50% radiation of pelvis; >= 6 wks must have elapsed if other substantial BM radiation. Patients with relapsed favorable histology Wilms tumor who received emergency radiation to preserve organ function are eligible and do not need to washout with the above criteria
• Patients may not be receiving any other investigational agents (within 4 weeks prior to study enrollment)
• Peripheral absolute neutrophil count (ANC) >= 750/uL (performed within 7 days prior to enrollment)
• Platelet count >= 75,000/uL (transfusion independent) (performed within 7 days prior to enrollment)
• Hemoglobin >= 8.0 g/dL (may receive red blood cell [RBC] transfusions) (performed within 7 days prior to enrollment)
• Patients with high-risk or very high-risk relapsed FHWT who will be treated with Regimen ICE/Cyclo/Topo, must have renal function assessed by creatinine clearance or radioisotope glomerular filtration rate (GFR) and meet the following requirement:
• Creatinine clearance or radioisotope GFR >= 60 mL/min/1.73 m^2 (performed within 7 days prior to enrollment)
• Patients diagnosed with stage 2-4 DAWT or standard risk relapsed FHWT, who will be treated with Regimen UH 3, may either obtain a creatinine clearance, radioisotope GFR (meeting the above criteria of GFR >= 60 mL/min/1.73 m^2), or an adequate serum creatinine as per the following table:
• Age: Maximum Serum Creatinine (mg/dL)
• 1 month to < 6 months: 0.4 (male and female)
• 6 months to < 1 year: 0.5 (male and female)
• 1 to < 2 years: 0.6 (male and female)
• 2 to < 6 years: 0.8 (male and female)
• 6 to < 10 years: 1 (male and female)
• 10 to < 13 years: 1.2 (male and female)
• 13 to < 16 years: 1.5 (male), 1.4 (female)
• >= 16 years: 1.7 (male), 1.4 (female)
• Total bilirubin =< 1.5 x upper limit of normal (ULN) for age or direct bilirubin =< ULN for patients whose total bilirubin > 1.5 x ULN (performed within 7 days prior to enrollment)
• Serum glutamic-oxaloacetic transaminase (SGOT) (aspartate aminotransferase [AST]) or serum glutamate pyruvate transaminase (SGPT) (alanine aminotransferase [ALT]) < 2.5 x upper limit of normal (ULN) for age or =< 5 x ULN for patients with liver metastases (performed within 7 days prior to enrollment)
• Shortening fraction of >= 27% by echocardiogram, or ejection fraction of >= 50% by radionuclide angiogram (performed within 7 days prior to enrollment)
• Patients with a history of bilateral Wilms tumor (synchronous or metachronous)
• Patients with any uncontrolled, intercurrent illness including, but not limited to, ongoing or active infection, or symptomatic congestive heart failure (defined as grade 2 or higher heart failure per Common Terminology Criteria for Adverse Events [CTCAE] version 5.0)
• Relapsed FHWT patients who did not receive frontline chemotherapy (e.g., very low risk FHWT initially observed without chemotherapy) or received only one chemotherapy agent for frontline therapy
• For patients with high-risk or very high-risk relapsed FHWT:
• Patients with renal tubular acidosis (RTA) as evidenced by serum bicarbonate < 16 mmol/L and serum phosphate =< 2 mg/dL (or < 0.8 mmol/L) without supplementation
• For stages 2-4 DAWT and standard-risk relapsed FHWT patients:
• Chronic inflammatory bowel disease and/or bowel obstruction
• Concomitant use of St. John's wort, which cannot be stopped prior to the start of trial treatment
• Female patients who are pregnant since fetal toxicities and teratogenic effects have been noted for several of the study drugs. A pregnancy test is required for female patients of childbearing potential
• Lactating females who plan to breastfeed their infants
• Sexually active patients of reproductive potential who have not agreed to use an effective contraceptive method for the duration of their study participation

• STEP 1 REGISTRATION AND RANDOMIZATION
• Patient must have the ability to understand and the willingness to sign a written informed consent document. Patients with impaired decision-making capacity (IDMC) who have a legally authorized representative (LAR) or caregiver and/or family member available will also be considered eligible
• Patient must have a diagnosis of high grade upper tract urothelial carcinoma proven by biopsy within 60 days prior to registration with one of the following:
• Upper urinary tract mass on cross-sectional imaging or
• Tumor directly visualized during upper urinary tract endoscopy before referral to medical oncology
• NOTE: Biopsy is standard of care (SOC) and required for enrollment to study. This is vital for best practice
• Leukocytes >= 3,000/mcL (obtained =< 14 days prior to registration)
• Platelets >= 100,000/mcL (obtained =< 14 days prior to registration)
• Total bilirubin =< 1.5 x institutional upper limit of normal (ULN) (or =< 2.5 x ULN for patients with Gilbert's disease) (obtained =< 14 days prior to registration)
• Aspartate aminotransferase (AST) (serum glutamic-oxaloacetic transaminase [SGOT])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) =< 2.5 x institutional ULN (obtained =< 14 days prior to registration)
• Hemoglobin (Hgb) >= 9 g/dL (obtained =< 14 days prior to registration)
• NOTE: Packed red blood transfusion is allowed to achieve this parameter as per treating investigator
• Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial
• NOTE: These patients must be stable on their anti-retroviral regimen with evidence of at least two undetectable viral loads within the past 6 months on the same regimen; the most recent undetectable viral load must be within the past 12 weeks. They must have a CD4 count of greater than 250 cells/mcL over the past 6 months on this same anti-retroviral regimen and must not have had a CD4 count < 200 cells/mcL over the past 2 years, unless it was deemed related to the cancer and/or chemotherapy induced bone marrow suppression. They must not be currently receiving prophylactic therapy for an opportunistic infection and must not have had an opportunistic infection within the past 6 months
• NOTE: For patients who have received chemotherapy in the past 6 months, a CD4 count < 250 cells/mcL during chemotherapy is permitted as long as viral loads were undetectable during this same chemotherapy. They must have an undetectable viral load and a CD4 count >= 250 cells/mcL within 7 days of registration
• For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated
• NOTE: Testing for HIV, hepatitis B or hepatitis C is not required unless clinically indicated
• Patients with a history of hepatitis C virus (HCV) infection must have been treated and have undetectable viral load. For patients with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load
• Patients with known history or current symptoms of cardiac disease, or history of treatment with cardiotoxic agents, should have a clinical risk assessment of cardiac function using the New York Heart Association Functional Classification. To be eligible for this trial, patients should be class 2B or better
• Patient must have a body weight of > 30 kg
• Patient must have a life expectancy of >= 12 weeks
• Patient must have a creatinine clearance > 15 ml/min as by Crockroft-Gault or 24-hour creatinine clearance within 28 days prior to registration
• NOTE: Patients will be assigned to cisplatin-ineligible and cisplatin-eligible cohorts based on their creatinine clearance, Eastern Cooperative Oncology Group (ECOG) performance status, and grade (if any) of peripheral neuropathy and hearing loss in keeping with SOC cisplatin contraindications. Patients that are cisplatin-eligible will be randomized to either Arm A or Arm B
• Patients that meet the following criteria will be assigned to the cisplatin-ineligible Arm C:
• Creatinine clearance of > 15 ml/min and =< 50 ml/min
• Patient must have an absolute neutrophil count (ANC) >= 1,000/mcL obtained =< 14 days prior to registration
• Patient must have ECOG performance status 0-2
• Patients that meet the following criteria will be randomized to cisplatin-eligible Arm A or Arm B:
• Patient must have an absolute neutrophil count (ANC) >= 1,500/mcL obtained =< 14 days prior to randomization
• Patient must have ECOG performance status 0-1
• Patient must have left ventricular ejection fraction (LVEF) >= 50% by (either multigated acquisition scan [MUGA] or 2-D echocardiogram) obtained within 28 days prior to randomization
• Patient must not have peripheral neuropathy >= grade 2 or hearing loss >= grade 3
• Patients must not have any component of small cell carcinoma. Other variant histologic types are permitted provided the predominant (>= 50%) subtype is urothelial carcinoma
• Patients must not be pregnant or breast-feeding due to the potential harm to an unborn fetus and possible risk for adverse events in nursing infants with the treatment regimens being used. All patients of childbearing potential must have a blood test or urine study within 14 days prior to registration to rule out pregnancy. A patient of childbearing potential is defined as any patient, regardless of sexual orientation or whether they have undergone tubal ligation, who meets the following criteria: 1) has achieved menarche at some point, 2) has not undergone a hysterectomy or bilateral oophorectomy; or 3) has not been naturally postmenopausal (amenorrhea following cancer therapy does not rule out childbearing potential) for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months)
• Patients of childbearing potential and sexually active patients must not expect to conceive or father children by using accepted and effective method(s) of contraception or by abstaining from sexual intercourse from the time of registration, while on study treatment and for at least 6 months after the last dose of protocol treatment
• Patient must have no evidence of metastatic disease or clinically enlarged lymph nodes (>= 1.0 cm short axis) on imaging required within 28 days prior to registration (solitary slightly enlarged lymph node with negative biopsy is allowed)
• NOTE: Patients with elevated alkaline phosphatase, calcium or suspicious bone pain/tenderness should also undergo baseline bone scans to evaluate for bone metastasis
• Patient must not have another active (or within 2 years) second malignancy other than resected non-melanoma skin cancers, resected in situ breast, cervical or other in situ carcinoma, and either clinically insignificant per the investigator (e.g. =< Gleason 3+4) on surveillance or previously treated prostate cancer with no rising prostate specific antigen (PSA) and no plan to treat
• NOTE: Patients with a prior or concurrent malignancy whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen are eligible for this trial. Patients in whom concomitant or prior bladder/urethra predominant (>= 50%) urothelial carcinoma have been surgically resected and demonstrated to be only non-invasive cancer (< cT1N0) are eligible regardless of time elapsed
• Patient must not have any uncontrolled illness including, but not limited to, ongoing or active infection including tuberculosis (clinical evaluation that includes clinical history, physical examination and radiographic findings, and tuberculosis [TB] testing in line with local practice), symptomatic congestive heart failure (CHF), myocardial infarction (MI) in last 3 months, or unstable angina pectoris, significant uncontrolled cardiac arrhythmia, liver cirrhosis, interstitial lung disease, or psychiatric illness/social situations that would limit compliance with study requirements
• Patient must not have received prior radiation therapy to >= 25% of the bone marrow for other diseases
• Patient must not have received prior systemic anthracycline therapy
• NOTE: Patients who have received prior intravesical chemotherapy at any time for non-muscle invasive urothelial carcinoma of the bladder are eligible
• Patient must not have an active autoimmune disease requiring immunosuppressive therapy within 2 years prior to registration or a history of inflammatory bowel disease (inflammatory bowel disease [IBD], colitis, or Crohn's disease), systemic lupus erythematosus, Sarcoidosis syndrome, Wegener syndrome or immune-related pneumonitis or interstitial lung disease. Patients with well-controlled hyper/hypothyroidism, celiac controlled by diet alone, diverticulosis, diabetes mellitus type I, vitiligo, alopecia, psoriasis, eczema, lichen planus, or similar skin/mucosa condition are eligible
• Patient must not be on or have used immunosuppressive medication within 14 days prior to the first dose of MEDI4736 (MEDI4736 (durvalumab). The following are exceptions to this criterion:
• Intranasal, inhaled, intra-auricular, topical steroids, or local steroid injections (e.g. intra-articular injection
• Systemic corticosteroids at physiologic doses not to exceed 10 mg/day of prednisone or its equivalent at the time of enrollment
• Steroids as premedications for hypersensitivity reactions (e.g. computed tomography [CT] scan premedication)
• Patient must not have a concomitant primary urothelial carcinoma of the bladder and/or urethra
• NOTE: Patients in whom concomitant or prior bladder/urethra predominant (>= 50%) urothelial carcinoma have been surgically resected and demonstrated to be only non-invasive cancer (< cT1N0) are eligible regardless of time elapsed
• Patient must not have prior history of muscle-invasive urothelial carcinoma with or without systemic chemotherapy (T2-4a and/or N1) within 2 years prior to registration
• NOTE: Patients who have no evidence of disease (NED) for more than 2 years from the latest therapy (surgery, radiation, chemotherapy, or clinical trial) are eligible
• Patient must not have received live attenuated vaccine within 30 days prior to the first dose of MEDI4736 (durvalumab), while on protocol treatment and within 30 days after the last dose of MEDI4736 (durvalumab)
• Patient must not have had a major surgical procedure (as defined by the Investigator) within 28 days prior to registration
• Patient must not have a history of allogenic organ transplantation

Part A and Part B Abbreviated
• ≥ 18 years of age
• Locally advanced or metastatic (Stage IV) solid tumor that has progressed during or after standard therapy, and for whom no available therapies are appropriate (based on investigator judgment)
• Patients in Part B with advanced or metastatic ccRCC, HCC, or NSCLC must have at least 1 measurable lesion per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1
• Patients with HCC in Part B must have at least 1 measurable target lesion according to modified RECIST (mRECIST)
• Patients with HCC must have unresectable disease, Barcelona Clinic Liver Cancer (BCLC1) Stage B (not eligible for transcatheter arterial chemoembolization [TACE]) or Stage C
• For patients in Part B with ccRCC, demonstrated progressive disease (PD) during or after the most recent treatment regimen. Prior treatment history must include progression during or after treatment with regimen(s) that have included a vascular endothelial growth growth factor (VEGF)-targeted agent and an immune checkpoint inhibitor. Patients who did not progress on but discontinued the VEGF-targeted agent for toxicity or intolerability are permitted.
• For patients in Part B with HCC, demonstrated PD during or after the most recent treatment regimen. Prior treatment history must include progression during or after treatment with a VEGF-targeted agent. Patients who did not progress on but discontinued the VEGF-targeted agent for toxicity or intolerability are permitted.
• For Part B patients in the tumor biopsy subsets only, must have tumor tissue that is accessible for pretreatment and on-treatment tumor biopsy in the opinion of the Investigator and be willing to undergo pretreatment and on-treatment biopsies per protocol
• Serum creatinine clearance ≥ 30 mL/min per Cockcroft-Gault formula or serum creatinine ≤ 2.0 x the upper limit of normal (ULN)
• Total bilirubin ≤ 1.5 x ULN (≤ 3 x ULN if elevated because of Gilbert's syndrome and ≤ 2 x ULN for patients with HCC or patients with known liver metastases)
• Aspartate aminotransferase (AST/SGOT) and alanine aminotransferase/serum glutamic pyruvic transaminase (ALT/SGPT) < 2.5 x ULN (< 5 x ULN if liver metastasis or for patients with HCC)
• For patients with HCC, Child-Pugh class A or B7 with a serum albumin ≥ 2.8 g/dL (≥ 28 g/L)
• Adequate hematologic function, defined as absolute neutrophil count (ANC) ≥ 1.0 x 109/L, hemoglobin ≥ 9.0 g/dL, and platelet count ≥ 100 x 109/L. For patients with HCC, platelet count ≥ 75 x 109/L without transfusion
• Eastern Cooperative Oncology Group (ECOG) performance status 0-1
• Patients with NSCLC must have histologically confirmed locally advanced and/or metastatic Stave IV NSCLC
• Patients with NSCLC must have demonstrated progressive disease during or after the most recent treatment regimen Part C Abbreviated
• ≥ 18 years of age
• Advanced RCC of any histology or advanced HCC previously treated with at least one systemic anticancer therapy
• Patients with HCC must have unresectable disease, Barcelona Clinic Liver Cancer (BCLC) Stage B (not eligible for transcatheter arterial chemoembolization) or Stage C
• At least 1 measurable lesion per RECIST 1.1
• Patients with HCC must have at least 1 measurable target lesion according to modified RECIST (mRECIST)
• ECOG performance status of 0-1
• ANC ≥1500/µL (1.5 x 109/L)
• Platelets ≥100 000/µL (≥ 100 x 109/L)
• Hemoglobin for participants with RCC: ≥9.0 g/dL; for participants with HCC: ≥8.5 g/dL
• Creatinine OR measured or calculated creatinine clearance (GFR can also be used in place of creatinine or CrCl) ≤1.5 × ULN OR ≥30 mL/min for participant with creatinine levels >1.5 × institutional ULN
• Total bilirubin ≤1.5 × ULN OR direct bilirubin ≤ULN for participants with total bilirubin levels >1.5 × ULN
• AST (SGOT) and ALT (SGPT) ≤2.5 × ULN (≤5 × ULN for participants with liver metastases)
• International normalized ratio (INR) OR prothrombin time (PT) Activated partial thromboplastin time (aPTT) ≤1.5 × ULN unless participant is receiving anticoagulant therapy as long as PT or aPTT is within therapeutic range of intended use of anticoagulants
• For patients with HCC, Child-Pugh Class A or B7 with a serum albumin ≥ 2.8 g/dL (≥ 28 g/L)
• Willingness of male and female patients who are not surgically sterile or postmenopausal to use medically acceptable methods of birth control for the duration of the study drug period (or beginning 14 days before the initiation of pembrolizumab for oral contraception), including 75 days after the last dose of SRF388 or 120 days after the last dose of pembrolizumab; male patients must refrain from donating sperm during this period. Sexually active men, and women using oral contraceptive pills, should also use barrier contraception with spermicide. Azoospermic male patients and WCBP who are continuously not heterosexually active are exempt from contraceptive requirements. However, female patients must still undergo pregnancy testing as described in this section. Part C Abbreviated Inclusion Criteria Specific to Patients with RCC or HCC from Part A or Part B:
• Progressed on SRF388 by RECIST 1.1
• Did not experience prior Grade ≥ 3 toxicity related to SRF388
• Willingness to undergo pretreatment core or excisional biopsy if deemed safe and tumor is accessible, in the opinion of the Investigator
• Has received no systemic anticancer therapies between SRF388 doses Part A and Part B Abbreviated
• Previously received an anti-IL-27 antibody or anti-IL-27 targeted therapy
• For patients in Part B with renal cell carcinoma (RCC), non-clear cell RCC histology
• For patients with HCC, known fibrolamellar or mixed hepatocellular cholangiocarcinoma
• For patients with HCC, fibrolamellar or mixed hepatocellular cholangiocarcinoma
• History of Grade 4 allergic or anaphylactic reaction to any monoclonal antibody therapy or any excipient in the study drugs
• Major surgery within 4 weeks prior to Screening
• Unstable or severe uncontrolled medical condition (eg, unstable cardiac function, unstable pulmonary condition including pneumonitis and/or interstitial lung disease, uncontrolled diabetes) or any important medical illness or abnormal laboratory finding that would, in the Investigator's judgment, increase the risk to the patient associated with his or her participation in the study Part C Abbreviated
• Is currently participating in or has participated in a study of an investigational agent or has used an investigational device within 4 weeks prior to the first dose of study drug
• Previously received an anti-IL 27 antibody or anti-IL 27 targeted therapy (exception to patients who received SRF388 in Part A or Part B)
• No prior systemic therapy for unresectable or metastatic disease
• Received > 5 prior systemic regimens for unresectible or metastatic disease (prior PD-(L)1 inhibitors are allowed if the patient did not discontinue therapy due to ≥ Grade 3 drug-related toxicity)
• For patients with HCC, fibrolamellar histology or mixed hepatocellular cholangiocarcinoma
• For patients with HCC, moderate or severe ascites
• For patients with HCC, inability to undergo disease evaluation with triphasic computed tomography or magnetic resonance imaging because of contrast allergy or other contraindication
• For patients with HCC, imaging findings consistent with ≥ 50% liver occupation by HCC tumors
• History of Grade 4 allergic or anaphylactic reaction to any monoclonal antibody therapy or any excipient in the study drugs
• Surgeries that required general anesthesia must be completed at least 2 weeks before first study drug administration
• Prior autologous stem cell transplant ≤ 3 months before the first dose
• Prior allogeneic hematopoietic cell transplant within 6 months of the first dose or with a history of or current clinical Graft-Versus-Host Disease
• Has had an allogenic tissue/solid organ transplant
• Other unstable or severe uncontrolled medical condition (eg, unstable cardiac function, unstable pulmonary condition, uncontrolled diabetes) or any important medical illness or abnormal laboratory finding that would, in the Investigator's judgment, increase the risk to the patient associated with his or her participation in the study

• Biopsy proven UTUC with plan for excisional surgery (distal ureterectomy or nephroureterectomy) with curative intent
• Age 18
•90 years
• Life expectancy > 1 year
• Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation, and for 90 days following completion of therapy. Female participants who become pregnant or who suspect that they are pregnant should notify the treating investigator immediately.
• Ability to understand and the willingness to sign a written informed consent.
• Concurrent or prior diagnosis of bladder cancer with a disease-free interval of less than three years.
• Synchronous bilateral upper tract urothelial carcinoma (prior history of contralateral UTUC is permissible with a disease-free interval of more than three years).
• Plan for radical cystectomy.
• 3.2.4 Suspicion for small bladder capacity (< 100 mL) based on treating urologist's clinical judgment.
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to gemcitabine or other agents used in study.

Key 1. Documented genetic ALK, ROS1, or NTRK1-3 alteration (point mutation, fusion, amplification) as identified by local testing in a Clinical Laboratory Improvement Amendments (CLIA) laboratory in the US or equivalently accredited diagnostic lab outside the United States (US) is required. 2. Phase 1: Age <12 years; Phase 2: Age 12- 25 years 3. Prior cytotoxic chemotherapy is allowed. 4. Prior immunotherapy is allowed. 5. Resolution of all acute toxic effects (excluding alopecia) of any prior anti-cancer therapy to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) Version 4.03 Grade less than or equal to 1. 6. All subjects must have measurable disease by RECIST v1.1 or Response Assessment in Neuro-Oncology Criteria (RANO) criteria at time of enrollment. 7. Subjects with a primary CNS tumor or CNS metastases must be neurologically stable on a stable or decreasing dose of steroids for at least 14 days prior to enrollment. 8. Subjects must have a Lansky (< 16 years) or Karnofsky (≥ 16 years) score of at least 50. 9. Life expectancy greater than or equal to 12 weeks. 10. Adequate hematologic, renal and hepatic function. Phase 2 1. Cohort Specific
• Cohort 1: Subjects with NTRK fusion gene positive (NTRK+) advanced solid tumors (including primary CNS tumors), that are tropomyosin receptor kinase (TRK) TKI naïve;
• Cohort 2: subjects with NTRK+ advanced solid tumors (including primary CNS tumors), that are TRK TKI pre-treated;
• Cohort 3: subjects with tumors or ALCL characterized by other ALK/ROS1/NTRK alterations or NTRK fusions without centrally confirmed measurable disease or not otherwise eligible for Cohort 1 or 2. 2. Subjects in Cohorts 1 and 2 must have prospectively confirmed measurable disease by BICR prior to enrollment. Key Exclusion Criteria (Phase 1 and Phase 2): 1. Subjects with neuroblastoma with only bone marrow disease evaluable by bone marrow aspiration only. 2. Major surgery within 14 days (2 weeks) of start of repotrectinib treatment. Central venous access (Broviac, Mediport, etc.) placement does not meet criteria for major surgery. 3. Known active infections (bacterial, fungal, viral including HIV positivity). 4. Gastrointestinal disease (e.g., Crohn's disease, ulcerative colitis, or short gut syndrome) or other malabsorption syndromes that would impact drug absorption. 5. Any of the following cardiac criteria:
• Mean resting corrected QT interval (ECG interval measured from the onset of the QRS complex to the end of the T wave) for heart rate (QTc) > 480 msec obtained from three ECGs, using the screening clinic ECG machine-derived QTc value
• Any clinically important abnormalities in rhythm, conduction, or morphology of resting ECG (e.g., complete left bundle branch block, third degree heart block, second degree heart block, PR interval > 250 msec)
• Any factors that increase the risk of QTc prolongation or risk of arrhythmic events such as heart failure, congenital long QT syndrome, family history of long QT syndrome, or any concomitant medication known to prolong the QT interval 6. Peripheral neuropathy of CTCAE ≥grade 2. 7. Subjects being treated with or anticipating the need for treatment with strong CYP3A4 inhibitors or inducers.

1. Signed informed consent and mental capability to understand the informed consent 2. Male or female patients > 18 years of age 3. Histologically or cytologically documented locally advanced or metastatic solid tumor malignancies refractory to or otherwise ineligible for treatment with standard-of-care agents/regimens, including but not limited to:
• Malignant melanoma
• Hormone receptor negative breast cancer
• Gastro-esophageal cancer
• Non-small cell lung cancer
• Head and neck cancer
• Hepatoma
• Renal cell carcinoma 4. Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 1 5. Evaluable or measurable disease as follows:
• A minimum of 3 RECIST-evaluable lesions: one that is suitable for injection and biopsied; one non-injected that will be biopsied for abscopal effect; and one measurable lesion that will be followed for response only.
• Injectable tumors shall be accessed by intralesional (cutaneous) or percutaneous injection only, including those lesions that are visible, palpable, or detectable by standard radiographic or ultrasound methods. Neither surgical procedures nor endoscopically-guided injections including those to endobronchial, endoluminal, or endosinusial spaces shall be allowed. While no anatomic locations are required or disallowed, lesions selected for intratumoral injection must, in the opinion of the investigator:
• Not be immediately adjacent to blood vasculature or other physiologic landmarks in such a way that will accrue undue safety risk to the patient
• Have longest diameter ≥ 10 mm and ≤ 50 mm
• Be fully efficacy evaluable per RECIST v1.1 criteria 6. Life expectancy > 3 months (Phase I) and > 6 months (Phase IIA) 7. ECG without evidence of clinically meaningful conduction abnormalities or active ischemia as determined by the investigator 8. Acceptable organ and marrow function as defined below:
• Absolute neutrophil count > 1,500 cells/μL
• Platelets > 50,000 cells/μL
• Total bilirubin ≤ 1.5 times the upper limit of normal (ULN)
• Aspartate aminotransferase (AST)/alanine transaminase (ALT) ≤ 2.5 times ULN. If liver metastases are present, AST/ALT < 5 times ULN
• Serum creatinine < 1.5 mg/dL and a measured creatinine clearance ≥ 50 mL/min using the Cockcroft-Gault formula
• Prothrombin time (PT)/partial thromboplastin time (PTT) ≤ 1.5 times ULN 9. Women of child-bearing potential (defined as a female who has experienced menarche and who has not undergone successful surgical sterilization (hysterectomy, bilateral salpingectomy, or bilateral oophorectomy) or is not postmenopausal (defined as amenorrhea for at least 12 consecutive months with an appropriate clinical profile at the appropriate age, e.g., greater than 45 years) must have a negative serum pregnancy test prior to first dose of study drug 10. Male and female patients with reproductive potential must agree to use two forms of highly effective contraception throughout the study 11. Phase I combination only: Demonstrated RECIST stable disease through ≥ 4 consecutive cycles of an approved PD-1 or PD-L1 targeted ICI with no Grade ≥ 3 CTCAE events considered by the investigator to be drug-related. 1. Anti-cancer therapy within 4 weeks or < 5 half-lives of the first dose of study drug. 2. Failure to recover to Grade 1 or less from clinically significant AEs due to prior anti-cancer therapy. 3. Known untreated brain metastases or treated brain metastases that have not been stable (scan showing no worsening of central nervous system (CNS) lesion[s] and no requirement of corticosteroids) ≥ 4 weeks prior to study enrollment 4. Baseline prolongation of QT/QTc interval (QTc interval > 470) 5. Uncontrolled intercurrent illness (including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations) that in opinion of the investigator would limit compliance with study requirements 6. Women who are pregnant or breastfeeding 7. Phase I combination only: Prior tumor progression through PD-1 or PD-L1 targeted ICI therapy.

• STEP I REGISTRATION CRITERIA
• Histologically documented renal cell carcinoma with clear cell component, including patients who have sarcomatoid features.
• Any metastatic disease, including visceral, lymph node, other soft tissue and bone, measurable per RECIST 1.1.
• Measurable disease as defined in the protocol.
• Must be intermediate or poor risk patient per International Metastatic Renal Cell Carcinoma Database (IMDC) criteria (1 or more of the following: Karnofsky performance status [KPS] < 80, < 1 year from diagnosis [including initial nephrectomy] to systemic treatment for metastatic disease, hemoglobin less than lower limit of normal [LLN], corrected calcium concentration greater than upper limit of normal [ULN], absolute neutrophil count greater than ULN, platelet count > ULN).
• Central nervous system (CNS) disease permitted, if stable and not otherwise causing symptoms or needing active treatment.
• Karnofsky performance status >= 70%.
• No prior treatment with PD-1, PD-L1, or CTLA-4 targeting agents (including but not limited to nivolumab, pembrolizumab, pidilizumab, durvalumab, atezolizumab, tremelimumab, and ipilimumab), or any other drug or antibody specifically targeting T-cell co-stimulation or checkpoint pathways. The only exception is for prior treatment with nivolumab or other PD-1/PD-L1/CTLA-4 targeting therapy on pre- or post-operative trials, as long as > 1 year since completion of systemic therapy.
• No prior previous systemic therapy for renal cell carcinoma (prior HD IL-2 [> 28 days] and prior adjuvant sunitinib > 180 days since completion and prior immunotherapy as above are allowed).
• No cancer therapy less than 28 days prior to registration; this includes radiation therapy, except for bone lesions less than 14 days prior to registration. There must be a complete recovery and no ongoing complications from radiotherapy.
• Not pregnant and not nursing, because this study involves an agent that has known genotoxic, mutagenic and teratogenic effects. Therefore, for women of childbearing potential only, a negative serum or urine pregnancy test done =< 14 days prior to registration is required.
• Age >= 18 years
• Absolute neutrophil count (ANC) >= 1,500/mm^3.
• Platelet count >= 100,000/mm^3.
• Hemoglobin >= 8 g/dL.
• Calculated (Calc.) creatinine clearance >= 30 mL/min.
• Urine protein =< 1+ or urine protein to creatinine (UPC) ratio < 1.
• Total bilirubin =< 1.5 x upper limit of normal (ULN).
• Aspartate aminotransferase/alanine aminotransferase (AST/ALT) =< 2.5 x upper limit of normal (ULN) or < 5 x ULN if hepatic metastases present.
• STEP 2 REGISTRATION ELIGIBILITY CRITERIA
• Successful completion of at least 1 cycle of ipilimumab/nivolumab.
• Resolution of any treatment-related adverse events to grade 1 or less per dose modification section (this criteria does not include any adverse events [AEs] not attributable to treatment which are present due to disease). Exceptions for this criteria include patients receiving replacement hormone treatments (such as levothyroxine for treatment-related hypothyroidism or glucocorticoid replacement for adrenal insufficiency). Please contact study chair if further discussion is needed.
• No more than 70 days from last dose of ipilimumab/nivolumab.
• Active autoimmune disease requiring ongoing therapy.
• Ongoing acute toxicity > grade 2 from previous treatment.
• History of severe allergic, anaphylactic or other hypersensitivity reactions to chimeric or humanized antibodies.
• History of human immunodeficiency virus (HIV) or active hepatitis B/C, or active tuberculosis (purified protein derivative [PPD] response without active TB is allowed).
• Concurrent use of immunosuppressive medication including prednisone above 10 mg daily.
• Uncontrolled adrenal insufficiency.
• Uncontrolled hypertension (systolic blood pressure [BP] >150 mmHg or diastolic BP > 90 mmHg).
• Major surgery less than 28 days prior to registration.
• Any serious non-healing wound, ulcer, or bone fracture within 28 days prior to registration.
• Any arterial thrombotic events within 180 days prior to registration.
• Clinically significant hematuria, hematemesis, or hemoptysis within 12 weeks prior to registration.
• Cavitating pulmonary lesions or known endotracheal or endobronchial disease manifestations.
• Lesions encasing or invading any major blood vessels (this does not include tumor thrombus extending into/through renal vein/inferior vena cava [IVC]). Patients with tumor thrombus extending into/through renal vein are considered eligible.
• Moderate of severe hepatic impairment (Child-Pugh B or C).
• Any history of untreated pulmonary embolism or deep venous thrombosis (DVT) in the 180 days prior to registration. (Any asymptomatic, treated pulmonary embolism or asymptomatic, treated deep venous thrombosis > 30 days prior to registration allowed).
• Corrected QT interval calculated by the Fridericia formula (QTcF) > 500 ms.
• Unstable cardiac arrhythmia within 6 months prior to registration.
• Any gastrointestinal (GI) bleeding =< 180 days, hemoptysis, or other signs of pulmonary hemorrhage =< 90 days prior to registration.
• History of abdominal fistula, gastrointestinal perforation, intra-abdominal abscess, bowel obstruction, or gastric outlet obstruction within 180 days prior to registration.
• Active peptic ulcer disease, inflammatory bowel disease, or malabsorption syndrome within 28 days prior to registration.
• Untreated hypothyroidism, evidence of pancreatitis, history of organ transplant, or history of congenital QT syndrome.
• Active treatment with coumarin agents (e.g., warfarin), direct thrombin inhibitors (e.g., dabigatran), direct Xa inhibitor betrixaban or platelet inhibitors (e.g., clopidogrel) within 5 days of registration. Allowed anticoagulants include: prophylactic use of low-dose aspirin for cardio-protection (per local applicable guidelines) and low-dose low molecular weight heparins (LMWH), therapeutic doses of LMWH or anticoagulation with direct factor Xa inhibitors rivaroxaban, edoxaban, apixaban. Allowed also in patients with known brain metastases who are on a stable dose of the anticoagulant for at least 1 week prior to registration without clinically significant hemorrhagic complications from the anticoagulation regimen or the tumor.
• Significant cardiac ischemia events (ST elevation myocardial infarction [STEMI] or non-ST elevation myocardial infarction [NSTEMI]) within 6 months or active NY Heart Association class 3-4 heart failure symptoms

1. Orthotopic heart transplantation 2. Age < 21 years at time of transplant 3. Stable immunosuppression at the time of randomization with no contraindication to everolimus, tacrolimus, or mycophenolate mofetil 4. Planned follow-up at a study site for the 30 month duration of the study. 5. Subject or legal adult representative capable of providing informed consent (in general, assent will be sought for children aged 12 years or older). 1. Multi-organ transplant (e.g. heart-lung or heart-liver). 2. Known hypersensitivity to everolimus, sirolimus, tacrolimus or mycophenolate mofetil (MMF), or to components of the drug products. 3. Patients on maintenance corticosteroid therapy exceeding a dose equivalent of prednisone 0.1 mg/kg/day at randomization. 4. High-risk for rejection defined as active rejection, recurrent (≥ 2 episodes of grade 2R rejection) cellular rejection, recurrent rejection (≥ 2 episodes of any grade) with hemodynamic compromise, steroid-resistant rejection or unresolved antibody-mediated rejection during the first 6 months post-heart transplant 5. Graft dysfunction (LVEF <40% or wedge pressure >22 mmHg or cardiac index <2.2 L/min/m2) 6. Stage 4 or 5 CKD (eGFR <30 ml/min/1.73 m2) or moderate proteinuria (urine protein to urine creatinine ratio >0.5 mg/mg). 7. Active infection requiring hospitalization or treatment dose medical therapy. 8. Patients with ongoing wound healing problems, clinically significant wound infection requiring continued therapy or other severe surgical complication in the opinion of the Site Principal Investigator. 9. Fasting Serum Cholesterol ≥300 mg/dL OR greater than or equal to 7.75 mmol/L, AND fasting triglycerides ≥2.5x the upper limit of normal (ULN). Note: In case one or both of these thresholds are exceeded, the patient can only be included after initiation of appropriate lipid lowering medication, and reduction of serum cholesterol and triglyceride levels to below exclusion ranges is confirmed. 10. Uncontrolled diabetes mellitus. 11. Diagnosis of post-transplant lymphoproliferative disorder (PTLD) during the first 6 months post-heart transplant. 12. History of non-adherence to medical regimens. 13. Patients who are treated with drugs that are strong inducers or inhibitors of cytochrome P450 3A4 (CYP3A4) and cannot discontinue the treatment 14. Patients who are pregnant or breast-feeding or intend to get pregnant during the study period.

1. 1 month of age up to < 18 years of age at the time of signing the informed consent. 2. Received HSCT within the past 6 months. 3. Diagnosis of TMA that persists despite initial management of any triggering condition. 4. Body weight ≥ 5 kilograms. 5. Female participants of childbearing potential and male participants with female partners of childbearing potential must use highly effective contraception starting at Screening and continuing until at least 8 months after the last dose of ravulizumab. 6. Participants must be vaccinated against meningococcal infections if clinically feasible, according to institutional guidelines for immune reconstitution after HSCT. Participants must be re-vaccinated against Haemophilus influenzae type b and Streptococcus pneumoniae if clinically feasible, according to institutional guidelines for immune reconstitution after HSCT. All participants should be administered coverage with prophylactic antibiotics according to institutional post-transplant infection prophylaxis guidances, including coverage against Neisseria meningitidis for at least 2 weeks after meningococcal vaccination. Participants who cannot receive meningococcal vaccine should receive antibiotic prophylaxis coverage against Neisseria meningitidis the entire Treatment Period and for 8 months following the final dose of ravulizumab. 1. Known familial or acquired 'a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13' deficiency (activity < 5%). 2. Known Shiga toxin-related hemolytic uremic syndrome. 3. Positive direct Coombs test. 4. Diagnosis or suspicion of disseminated intravascular coagulation. 5. Known bone marrow/graft failure. 6. Diagnosis of veno-occlusive disease. 7. Human immunodeficiency virus (HIV) infection (evidenced by HIV-1 or HIV-2 antibody titer). 8. Unresolved meningococcal disease. 9. Presence or suspicion of sepsis (treated or untreated) within 7 days prior to Screening. 10. Pregnancy or breastfeeding. 11. Hypersensitivity to murine proteins or to 1 of the excipients of ravulizumab. 12. Previously or currently treated with a complement inhibitor.

1. Prior SOT of kidney, liver, heart, lung, pancreas, small bowel, or any combination of these (SOT cohort); or prior allogeneic HCT (HCT cohort) 2. A diagnosis of locally-assessed, biopsy-proven EBV+ PTLD 3. Availability of appropriate partially HLA-matched and restricted tabelecleucel has been confirmed by the sponsor 4. Measurable, 18F-deoxyglucose (FDG)-avid (Deauville score ≥ 3) systemic disease using Lugano Classification response criteria by positron emission tomography (PET)-diagnostic computed tomography (CT), except when contraindicated or mandated by local practice, then magnetic resonance imaging (MRI) may be used.For subjects with treated central nervous system (CNS) disease, a head CT and/or brain/spinal MRI as clinically appropriate will be required to follow CNS disease response per Lugano Classification response criteria. 5. Treatment failure of rituximab or interchangeable commercially available biosimilar monotherapy (SOT subgroup A or HCT cohort) or rituximab plus any concurrent or sequentially administered chemotherapy regimen (SOT subgroup B) for treatment of PTLD. 6. Eastern Cooperative Oncology Group performance status ≤ 3 for subjects aged ≥ 16 years; Lansky score ≥ 20 for subjects < 16 years 7. For HCT cohort only: If allogeneic HCT was performed as treatment for an acute lymphoid or myeloid malignancy, the underlying primary disease for which the subject underwent transplant must be in morphologic remission 8. Adequate organ function 1. Absolute neutrophil count ≥ 1000/μL, (SOT cohort) or ≥ 500/μL (HCT cohort), with or without cytokine support 2. Platelet count ≥ 50,000/μL, with or without transfusion or cytokine support. For HCT cohort, platelet count < 50,000/μL but ≥ 20,000/μL, with or without transfusion support, is permissible if the subject has not had grade ≥ 2 bleeding in the prior 4 weeks (where grading of the bleeding is determined per the National Cancer Institute's Common Terminology Criteria for Adverse Events [CTCAE], version 5.0) 3. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin each < 5 × the upper limit of normal; however, ALT, AST, and total bilirubin each ≤ 10 × upper limit of normal is acceptable if the elevation is considered by the investigator to be due to EBV and/or PTLD involvement of the liver as long as there is no known evidence of significant liver dysfunction 9. Subject or subject's representative is willing and able to provide written informed consent 1. Burkitt lymphoma, classical Hodgkin lymphoma, or any T cell lymphoma 2. Daily steroids of > 0.5 mg/kg prednisone or glucocorticoid equivalent, ongoing methotrexate, or extracorporeal photopheresis 3. Untreated CNS PTLD or CNS PTLD for which the subject is actively receiving CNS-directed chemotherapy (systemic or intrathecal) or radiotherapy at enrollment. NOTE:Subjects with previously treated CNS PTLD may enroll if CNS-directed therapy is complete. 4. Suspected or confirmed grade ≥ 2 graft-versus-host disease (GvHD) per the Center for International Blood and Marrow Transplant Research consensus grading system at enrollment 5. Ongoing or recent use of a checkpoint inhibitor agent (eg, ipilimumab, pembrolizumab, nivolumab) within 3 drug half-lives from the most recent dose to enrollment 6. For HCT cohort: active adenovirus viremia 7. Need for vasopressor or ventilatory support 8. Antithymocyte globulin or similar anti-T cell antibody therapy ≤ 4 weeks prior to enrollment 9. Treatment with Epstein-Barr virus cytotoxic T lymphocytes or chimeric antigen receptor T cells directed against B cells within 8 weeks of enrollment (SOT or HCT cohorts), or unselected donor lymphocyte infusion within 8 weeks of enrollment (HCT cohort only) 10. Female who is breastfeeding or pregnant or female of childbearing potential or male with a female partner of childbearing potential unwilling to use a highly effective method of contraception 11. Inability to comply with study-related procedures

• Documentation of disease
• Histologic documentation: Histologically or cytologically confirmed urothelial carcinoma (UC) with predominantly transitional-cell features
• Stage: Locally advanced or metastatic disease prior to starting immune checkpoint blockade
• Tumor Site: Bladder, renal pelvis, ureter, urethra, or prostate
• Patients must have received at least one cycle of current active treatment with standard of care (SOC) Food and Drug Administration (FDA) approved PD-1/L1 immune checkpoint inhibitor (ICI)-containing therapy for locally advance or metastatic UC
• Patients without progressive disease per Response Evaluation Criteria in Solid Tumors (RECIST) version (v) 1.1 guidelines (i.e., with an ongoing [complete response] CR, partial response [PR], or stable disease [SD]) following completion of 12-15 months of ICI treatment
• No history of tuberculosis, active hepatitis B (HBV) or hepatitis C (HCV), or uncontrolled human immunodeficiency virus (HIV)
• Patients with resolved HBV infection, defined as positive hepatitis B core antibody (anti-Hb) and negative hepatitis B surface antigen (HbsAg), are eligible
• Patients with positive HCV antibody are eligible if HCV ribonucleic acid (RNA) polymerase chain reaction (PCR) is negative
• Patients with HIV who are compliant with highly active antiretroviral therapy (HAART) and have normal CD4 count and undetectable viral load are eligible
• No history of allogeneic organ transplantation
• No current immunosuppressive medication exceeding 10 mg/day of prednisone or its equivalent * Patients with pre-existing or treatment-emergent autoimmune or inflammatory disorders which do not require systemic immunosuppressive treatment exceeding 10 mg/day of prednisone or its equivalent may be included
• No history of another primary malignancy except for malignancy treated with curative intent with no known active disease for >= 2 years, and adequately treated non-melanomatous skin cancer or carcinoma in situ (e.g. cervical carcinoma in situ [CIS]) without evidence of disease
• No female patients who are pregnant or breastfeeding, or male or female patients of reproductive potential who are not willing to employ effective birth control, because this study involves investigational agents whose genotoxic, mutagenic, and teratogenic effects on the developing fetus and newborn are unknown. Therefore, for women of childbearing potential only, a negative urine or serum pregnancy test pregnancy test done =< 14 days prior to registration is required REGISTRATION ELIGIBILITY CRITERIA:
• Patients without progressive disease per RECIST v 1.1 guidelines (i.e., with an ongoing CR, PR or SD) following completion of 12-15 months of ICI treatment
• No toxicity from ICI therapy that makes continuation of treatment clinically unacceptable
• Adequate bone marrow and organ functions to continue PD-1/L1 ICI as judged by the treating physician
• Age >= 18 years
• Eastern Cooperative Oncology Group (ECOG) performance status 0-2
• Central nervous system (CNS) metastasis is allowed if radiographically stable, clinically asymptomatic, and prior local therapy (if received) was completed > 6 months before registration
• No history of tuberculosis, active hepatitis B (HBV) or hepatitis C (HCV), or uncontrolled human immunodeficiency virus (HIV)
• Patients with resolved HBV infection, defined as positive hepatitis B core antibody (anti-Hb) and negative hepatitis B surface antigen (HbsAg), are eligible
• Patients with positive HCV antibody are eligible if HCV RNA PCR is negative
• Patients with HIV who are compliant with highly active antiretroviral therapy (HAART) and have normal CD4 count and undetectable viral load are eligible

• Metastatic disease defined as new or progressive lesions on cross-sectional imaging or bone scan. Patients must have at least:
• One measurable site of disease as per Response Evaluation Criteria in Solid Tumors (RECIST) version (v) 1.1
• One bone lesion on bone scan (tec99 or sodium fluoride [NaF] positron emission tomography [PET]/computed tomography [CT], CT, or magnetic resonance imaging [MRI]) for the bone-only cohort
• Histologically confirmed diagnosis of one of the following metastatic cohorts:
• Small cell/ neuroendocrine carcinoma of the bladder
•All urothelial carcinomas with any amount of neuroendocrine differentiation (including small cell differentiation) will be included. If the tumor is purely neuroendocrine, metastasis from another site of origin should be clinically excluded.
• Adenocarcinoma of the bladder, or urachal adenocarcinoma, or bladder/urethra clear cell adenocarcinoma
•must be pure (per World Health Organization [WHO] definition), (i.e. urothelial carcinoma with glandular differentiation is not considered a pure adenocarcinoma.
• Squamous cell carcinoma of the bladder
•must be pure (i.e. urothelial carcinoma with squamous differentiation is not considered a pure squamous cell carcinoma).
• Plasmacytoid urothelial carcinoma
•Tumor should show predominantly > or equal ~50% plasmacytoid histology (including all types of discohesive growth, such as tumors with signet-ring and/or rhabdoid features as well).
• Any penile cancer
• Sarcomatoid renal cell carcinoma
•Tumor should be predominantly sarcomatoid ~50% (including rhabdoid differentiation) is also unclassified renal cell carcinomas (RCCs): all (assuming they are high grade with metastasis) malignant angiomyolipomas are allowed.
• Sarcomatoid urothelial carcinoma
•Tumor should show predominantly ~ 50% sarcomatoid differentiation.
• Renal medullary carcinoma
•Per WHO definition, ideally confirmed with immunostains.
• Renal collecting duct carcinoma
•Per WHO definition (medullary involvement, predominant tubular morphology, desmoplastic stromal reaction, high grade cytology, infiltrative growth pattern, and absence of other renal cell carcinoma subtype or urothelial carcinoma).
• Bone only urothelial carcinoma or other non-prostate GU tumor
• Urethra carcinoma
•May be of any histology but if urothelial carcinoma then must be isolated to the urethra and not have metachronous or synchronous urothelial carcinoma of the bladder.
• Other miscellaneous histologic variants of the urothelial carcinoma, such as, but not limited to: micropapillary (Tumor should show predominantly > or equal 50% micropapillary architecture), giant cell, lipid-rich, clear cell and nested variants (Tumor should predominantly > or equal 50% show these features), large cell neuroendocrine carcinoma, lymphoepithelioma-like carcinoma and mixed patterns will be considered, as well as small cell neuroendocrine prostate cancer (Only treatment-naïve primary small cell of prostate with any amount of small cell component allowed. Post-treatment small cell prostatic carcinomas are not allowed), Malignant testicular Sertoli or Leydig cell tumors, and papillary and chromophobe RCC.
• Note: Translocation positive renal cell carcinoma patients are eligible. However, AREN1721 should be considered before this trial.
• Hematoxylin and eosin (H&E) slides from diagnostic tumor tissue for retrospective central pathology review
• Patients may have received up to 2 systemic anti-cancer treatments or be treatment naive. Patients with small cell carcinoma should have received a platinum-based combination regimen either as neoadjuvant, adjuvant or first-line treatment). Patients in the bone-only cohort may be urothelial carcinoma histology but must receive standard cisplatin-based chemotherapy (if cisplatin-eligible).
• Patients must be able to swallow oral formulation of the tablets
• Karnofsky performance status >= 80%
• Absolute neutrophil count (ANC) >= 1,000/mcL
• Platelet count >= 75,000/mcL
• Total bilirubin =< 1.5 x upper limit of normal (ULN). For subjects with known Gilbert's disease or similar syndrome with slow conjugation of bilirubin, total bilirubin =< 3.0 mg/dL
• Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) =< 3.0 x institutional upper limit of normal (ULN) (or =< 5 x ULN for patients with liver metastases or Gilbert's disease)
• Creatinine =< 1.5 x upper limit of normal (ULN) OR creatinine clearance >= 40 mL/min/1.73 m^2 (calculated using the Chronic Kidney Disease Epidemiology [CKD-EPI] equation or Cockcroft-Gault formula) for patients with creatinine levels above institutional normal
• Hemoglobin >= 9 g/dL (transfusion of packed red blood cells [PRBCs] allowed)
• Serum albumin >= 3.2 g/dL
• Lipase and amylase =< 2.0 x ULN and no radiologic (on baseline anatomical imaging) or clinical evidence of pancreatitis
• Prior treatment with MET or VEGFR inhibitors is allowed. However, prior cabozantinib will not be allowed. Also, patients that have received both prior MET or VEGF and prior PD-1/PD-L1/CTLA-4 (sequentially or in combination) are also not allowed
• Prior treatment with any therapy on the PD-1/PD-L1 axis or anti- CTLA-4/CTLA-4 inhibitors is allowed, either in the perioperative or in the metastatic setting. However, patients that have received both prior MET or VEGF and prior PD-1/PD-L1/CTLA-4 (sequentially or in combination) are not allowed
• Human immunodeficiency virus (HIV)-positive patients are eligible if on stable dose of highly active antiretroviral therapy (HAART), no clinically significant drug-drug interactions are anticipated with the current HAART regimen, CD4 counts are greater than 350 and viral load is undetectable
• Patients with rheumatoid arthritis and other rheumatologic arthropathies, Sjogren's syndrome and psoriasis controlled with topical medication only and patients with positive serology, such as antinuclear antibodies (ANA), anti-thyroid antibodies etc. are eligible but should be considered for rheumatologic evaluation for the presence of target organ involvement and potential need for systemic treatment
• Patients with vitiligo, endocrine deficiencies including thyroiditis managed with replacement hormones or medications (e.g. thyroiditis managed with propylthiouracil [PTU] or methimazole) including physiologic oral corticosteroids are eligible
• Patients who have evidence of active or acute diverticulitis, intra-abdominal abscess, and gastrointestinal (GI) obstruction, within 12 months are not eligible
• Women of childbearing potential must have a negative pregnancy test =< 7 days prior to registration
• Women of childbearing potential include women who have experienced menarche and who have not undergone successful surgical sterilization (hysterectomy, bilateral tubal ligation, or bilateral oophorectomy) or are not postmenopausal. Post menopause is defined as amenorrhea >= 12 consecutive months. Note: women who have been amenorrheic for 12 or more months are still considered to be of childbearing potential if the amenorrhea is possibly due to prior chemotherapy, antiestrogens, ovarian suppression or any other reversible reason
• Pregnant women may not participate in this study because with cabozantinib, nivolumab, and ipilimumab have potential for teratogenic or abortifacient effects. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with cabozantinib, nivolumab, and ipilimumab, breastfeeding should be discontinued if the mother is treated with these agents
• The patient has received no cytotoxic chemotherapy (including investigational cytotoxic chemotherapy) or biologic agents (e.g., cytokines or antibodies) within 2 weeks before the first dose of study treatment
• The patient has received no radiation therapy:
• To the lungs and mediastinum or abdomen within 4 weeks before the first dose of study treatment, or has ongoing complications, or is healing from prior radiation therapy
• To brain metastasis within 3 weeks for whole-brain radiotherapy (WBXRT), and 2 weeks for stereotactic body radiation therapy (SBRT) before the first dose of study treatment
• To the abdomen within 4 weeks before the first dose of study treatment, or has ongoing complications, or is healing from prior radiation therapy
• To any other site(s) within 2 weeks before the first dose of study treatment
• The patient has received no radionuclide treatment within 6 weeks of the first dose of study treatment
• The patient has received no prior treatment with a small molecule kinase inhibitor within 14 days or five half-lives of the compound or active metabolites, whichever is longer, before the first dose of study treatment
• The patient has received no prior treatment with hormonal therapy within 14 days or five half-lives of the compound or active metabolites, whichever is longer, before the first dose of study treatment. Subjects receiving gonadotropin-releasing hormone (GnRH) agonists and antagonists are allowed to participate
• The patient has not received any other type of investigational agent within 14 days before the first dose of study treatment
• The patient must have recovered to baseline or Common Terminology Criteria for Adverse Events (CTCAE) =< grade 1 from toxicity due to all prior therapies except alopecia, neuropathy and other non-clinically significant adverse events (AEs) defined as lab elevation with no associated symptoms or sequelae
• The patient may not have active brain metastases or epidural disease. Patients with brain metastases previously treated with whole brain radiation or radiosurgery who are asymptomatic and do not require steroid treatment for at least 2 weeks before starting study treatment are eligible. Neurosurgical resection of brain metastases or brain biopsy is permitted if completed at least 3 months before starting study treatment. Baseline brain imaging with contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) scans for subjects with known brain metastases is required to confirm eligibility
• No concomitant treatment with warfarin. Aspirin (up to 325 mg/day), thrombin or factor Xa inhibitors, low-dose warfarin (=< 1 mg/day), prophylactic and therapeutic low molecular weight heparin (LMWH) are permitted
• No chronic concomitant treatment with strong CYP3A4 inducers (e.g., dexamethasone, phenytoin, carbamazepine, rifampin, rifabutin, rifapentine, phenobarbital, and St. John's wort) or strong CYP3A4 inhibitors
• Because the lists of these agents are constantly changing, it is important to regularly consult medical reference texts such as the Physicians' Desk Reference may also provide this information. As part of the enrollment/informed consent procedures, the patient will be counseled on the risk of interactions with other agents, and what to do if new medications need to be prescribed or if the patient is considering a new over-the-counter medicine or herbal product
• The patient has not experienced any of the following:
• Clinically-significant gastrointestinal bleeding within 6 months before the first dose of study treatment
• Hemoptysis of >= 0.5 teaspoon (2.5 mL) of red blood per day within 1 months before the first dose of study treatment
• Any other signs indicative of pulmonary hemorrhage within 3 months before the first dose of study treatment
• The patient has no tumor invading any major blood vessels
• The patient has no evidence of tumor invading the GI tract (esophagus, stomach, small or large bowel, rectum or anus), or any evidence of endotracheal or endobronchial tumor within 28 days before the first dose of cabozantinib. Patients with rectal tumor masses are not eligible.
• The patient has no uncontrolled, significant intercurrent or recent illness including, but not limited to, the following conditions:
• Cardiovascular disorders including:
• Congestive heart failure (CHF): New York Heart Association (NYHA) class III (moderate) or class IV (severe) at the time of screening.
• Concurrent uncontrolled hypertension defined as sustained blood pressure (BP) > 150 mm Hg systolic, or > 90 mm Hg diastolic despite optimal antihypertensive treatment within 7 days of the first dose of study treatment
• The subject has a corrected QT interval calculated by the Fridericia formula (QTcF) > 500 ms within 28 days before randomization. Note: if initial QTcF is found to be > 500 ms, two additional electrocardiograms (EKGs) separated by at least 3 minutes should be performed. If the average of these three consecutive results for QTcF is =< 500 ms, the subject meets eligibility in this regard
• Any history of congenital long QT syndrome
• Any of the following within 6 months before registration of study treatment:
• Unstable angina pectoris
• Clinically-significant cardiac arrhythmias (patients with atrial fibrillation are eligible)
• Stroke (including transient ischemic attack [TIA], or other ischemic event)
• Myocardial infarction
• Cardiomyopathy
• No significant gastrointestinal disorders particularly those associated with a high risk of perforation or fistula formation including:
• Any of the following that have not resolved within 28 days before the first dose of study treatment:
• Active peptic ulcer disease
• Acute diverticulitis, cholecystitis, symptomatic cholangitis or appendicitis, or malabsorption syndrome
• None of the following within 2 years before the first dose of study treatment:
• Abdominal fistula or genitourinary fistula
• Gastrointestinal perforation
• Bowel obstruction or gastric outlet obstruction
• Intra-abdominal abscess. Note: Complete resolution of an intra-abdominal abscess must be confirmed prior to initiating treatment with cabozantinib even if the abscess occurred more than 2 years before the first dose of study treatment
• Disorders associated with a high risk of fistula formation including percutaneous endoscopic gastrostomy (PEG) tube placement are not eligible
• No other clinically significant disorders such as:
• Severe active infection requiring IV systemic treatment within 14 days before the first dose of study treatment
• Serious non-healing wound/ulcer/bone fracture within 28 days before the first dose of study treatment
• History of organ or allogeneic stem cell transplant
• Concurrent uncompensated hypothyroidism or thyroid dysfunction within 7 days before the first dose of study treatment (for asymptomatic patients with an elevated thyroid-stimulating hormone [TSH], thyroid replacement may be initiated if clinically indicated without delaying the start of study treatment)
• No history of major surgery as follows:
• Major surgery within 3 months of the first dose of ca

• Provide written informed consent
• Histologically confirmed cancers for which no curative therapy exists
• Documented HER2 or EGFR exon 18 mutation
• Participants must agree and commit to use appropriate methods of contraception as outlined in the protocol
• At least one measurable lesion, defined by RECIST v1.1
• Participants harboring ineligible somatic HER2 mutations
• Prior treatment with any HER2-directed tyrosine kinase inhibitor (e.g., lapatinib, afatinib, dacomitinib, neratinib) is excluded with the following exception: patients with EGFR exon 18 mutated NSCLC who may have received afatinib, osimertinib, or other pan HER or EGFR TKIs remain eligible
• Participants who are receiving any other anticancer agents
• Symptomatic or unstable brain metastases
• Women who are pregnant or breast-feeding There are additional inclusion and exclusion criteria. The study center will determine if criteria for participation are met.

• Participants must have one of the following:
• Histologically documented muscle-invasive bladder carcinoma (MIBC) from transurethral resection of bladder tumor (TURBT) within 56 days prior to registration
• Histologically confirmed high grade upper tract urothelial carcinoma (UTUC) within 56 days prior to registration, with invasion confirmed by either a mass on cross-sectional imaging or a tumor directly visualized during upper urinary tract endoscopy within 56 days prior to registration
• Participants diagnosed with mixed urothelial carcinoma and variant histology within 56 days prior to registration may be eligible if the majority (> 50%) of the tumor consists of urothelial carcinoma. Participants with pure non-urothelial variant histologies or any small cell histology are not eligible
• Participants must have clinical stage T2-T4aN0M0 bladder or upper tract cancer confirmed by radiologic staging (computed tomography [CT] scan/magnetic resonance imaging [MRI] abdomen and pelvis, and CT scan/x-ray of the chest) within 56 days prior to registration
• Participants must have a bone scan within 56 days prior to registration if they have bone pain or elevated serum alkaline phosphatase
• Participants must have a bimanual examination under anesthesia within 56 days prior to registration
• Participants must not have received prior systemic chemotherapy, immunotherapy or radiotherapy for the treatment of muscle invasive bladder cancer (MIBC) or upper tract urothelial carcinoma (UTUC). Other prior pelvic radiotherapy is allowed if it does not preclude surgery (radical cystectomy, nephroureterectomy or ureterectomy, based on location of primary tumor). Prior intravesical therapy is allowed
• Participants must not have received immunosuppressive medication within 14 days prior to registration, with the exception of intranasal, inhaled, topical steroids, or local steroid injections (e.g., intra-articular injection) systemic corticosteroids at physiologic doses not to exceed 10 mg/day of prednisone or its equivalent
• Participants must be >= 18 years of age
• Participants must have Zubrod performance status 0-2
• Participants must have history and physical examination within 28 days prior to registration
• Participants must be surgical candidates as deemed by the local site oncologic surgeon within 28 days prior to registration. This must be clearly documented
• Participants must have a serum creatinine =< the institutional upper limit of normal (IULN) OR measured OR calculated creatinine clearance >= 30 mL/min using the Crockroft-Gault Formula. This specimen must have been drawn and processed within 28 days prior to registration
• Participants must be deemed cisplatin-ineligible based on greater than or equal to 1 of the following:
• Zubrod performance status = 2
• Creatinine clearance (calculated by Crockroft-Gault formula or measured) 30 to < 60 ml/min,
• Neuropathy > grade 1
• Hearing loss > grade 1
• Congestive heart failure > grade 2
• Hemoglobin >= 9.0 g/dL (within 28 days prior to registration)
• Absolute neutrophil count >= 1,500/mcL (within 28 days prior to registration)
• Platelets >= 100,000/mcL (within 28 days prior to registration)
• Total bilirubin =< 1.5 x institutional upper limit of normal (ULN) (within 28 days prior to registration)
• Aspartate aminotransferase (AST) =< 2.5 x institutional ULN (within 28 days prior to registration)
• Alanine aminotransferase (ALT) =< 2.5 x institutional ULN (within 28 days prior to registration)
• Participants with known history or current symptoms of cardiac disease, or history of treatment with cardiotoxic agents, must have a clinical risk assessment of cardiac function using the New York Heart Association Functional Classification and be class 2B or better
• Participants with known human immunodeficiency virus (HIV) must be on effective anti-retroviral therapy and have undetectable viral load at their most recent viral load test and within 6 months prior to registration
• Participant must not have any other prior malignancy except for the following: adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer, prostate cancer Gleason score =< 3+4 in active surveillance, adequately treated stage I or II cancer from which the participant is currently in complete remission, or any other cancer from which the participant has been disease free for two years
• Participants must not be pregnant or nursing due to the risk of harm to a fetus or nursing infant. Women/men of reproductive potential must have a negative serum or urine pregnancy test within 28 days prior to registration and must have agreed to use an effective contraceptive method. A woman is considered to be of "reproductive potential" if she has had menses at any time in the preceding 12 consecutive months. In addition to routine contraceptive methods, "effective contraception" also includes heterosexual celibacy and surgery intended to prevent pregnancy (or with a side-effect of pregnancy prevention) defined as a hysterectomy, bilateral oophorectomy or bilateral tubal ligation. However, if at any point a previously celibate participant chooses to become heterosexually active during the time period for use of contraceptive measures outlined in the protocol, he/she is responsible for beginning contraceptive measures
• Participants must not have a history of active primary immunodeficiency
• Participants must not have a history of or active autoimmune or inflammatory disorder, with the exception of vitiligo, alopecia, hypothyroidism (stable on hormone replacement), or chronic skin condition that does not require systemic therapy

• Patients with histologically confirmed solid tumor malignancies with residual tumors present that require standard of care chemotherapy for a minimum number of cycles. All anatomical sites and all tumor histologies are eligible including central nervous system tumors.
• Patients ages 13
•25 years
• In the opinion of the investigator, patients must be thought to be able to lie still for imaging without sedation for 20
•30 minutes.
• Patients must have a performance status of > 50% (Lansky or Karnofsky).
• Patients of childbearing potential must have a negative urine or serum pregnancy test as per institution's standard of care within 7 days prior to [18F]FLT PET/CT imaging
• Ability to understand and the willingness to sign a written informed consent/assent.
• Patients with known allergic or hypersensitivity reactions to previously administered radiopharmaceuticals of similar chemical or biologic composition to [18F]FLT
• Subjects who had prior chemotherapy or radiotherapy before enrollment in the study.
• Subjects for whom chemotherapy is not a standard of care primary therapy option.
• Patients who are pregnant or breast-feeding
• Patients with no residual tumor (i.e. complete resection at diagnosis)

• All participants 12 to <18 years old must have documented positive CMV serostatus (CMV IgG seropositive) for the recipient (R+) within 90 days prior to enrollment. Participants from birth to <12 years old must have documented positive CMV serostatus (CMV IgG seropositive) for the recipient (R+) within 90 days prior to enrollment and/or the donor (D+); the donor serostatus should be documented within 1 year prior to enrollment.
• Is the recipient of a first allogeneic HSCT (bone marrow, peripheral blood stem cell, or cord blood transplant).
• Has undetectable CMV DNA from a plasma or whole blood sample collected within 5 days prior to enrollment.
• Is within 28 days post-HSCT at the time of enrollment.
• Females are not pregnant, not breastfeeding,and is not a woman of childbearing potential (WOCBP); or is a WOCBP who agrees to follow the contraceptive guidance during the treatment period and for at least 28 days after the last dose of study intervention.
• Participants from 2 to <18 years of age must not be on concomitant Cyclosporin A (CsA), and must be able to take LET tablets or the oral granules (either by mouth or via G tube/NG tube), provided the participant does not have a condition that may interfere with the absorption of oral medication (e.g. vomiting, diarrhea, or a malabsorptive condition) from the day of enrollment until the intensive PK sampling is completed in these participants.
• For participants 2 <12 years old their weight should be at least 10 kg; for participants from birth to <2 years old their weight should be at least 2.5 kg and less than or equal to 15 kg at the time of enrollment.
• Has received a previous allogeneic HSCT (Note: receipt of a previous autologous HSCT is acceptable).
• Has a history of CMV end-organ disease within 6 months prior to enrollment.
• Has evidence of CMV viremia at any time from either signing of the ICF or the HSCT procedure, whichever is earlier, until the time of enrollment.
• Has suspected or known hypersensitivity to active or inactive ingredients of LET formulations.
• Has severe hepatic insufficiency within 5 days prior to enrollment.
• Is a) on renal replacement therapy (eg, hemodialysis, peritoneal dialysis) OR b) has end-stage renal impairment.
• Has both moderate hepatic insufficiency and moderate-to-severe renal insufficiency.
• Has an uncontrolled infection on the day of enrollment.
• Requires mechanical ventilation or is hemodynamically unstable at the time of enrollment.
• Has a documented positive result for a human immunodeficiency virus antibody (HIVAb) test at any time prior to enrollment, or for hepatitis C virus antibody (HCV-Ab) with detectable HCV RNA, or hepatitis B surface antigen (HBsAg) within 90 days prior to enrollment.
• Has active solid tumor malignancies with the exception of localized basal cell or squamous cell skin cancer or the condition under treatment (e.g. lymphomas).
• Has a preexisting cardiac condition a) for which the patient is currently being treated or b) which required hospitalization within the last 6 months or c) that may be expected to recur during the course of the trial.
• Has received within 7 days prior to screening any of the following: ganciclovir; valganciclovir; foscarnet; acyclovir; valacyclovir; famciclovir.
• Has received within 30 days prior to screening of any of the following: cidofovir; CMV immunoglobulin; any investigational CMV antiviral agent/biologic therapy; Rifampin and other strong inducers (such as phenytoin, carbamazepine, St John's wort (Hypericum perforatum), rifabutin and phenobarbital) and moderate inducers such as nafcillin, thioridazine, modafinil and bosentan.
• Has received LET at any time prior to enrollment in this study.
• Is currently participating or has participated in a study with an unapproved investigational compound or device within 28 days, or 5X half-life of the investigational compound (excluding monoclonal antibodies), whichever is longer, of initial dosing in this study.
• Has previously participated in this study or any other study involving LET.
• Has previously participated or is currently participating in any study involving administration of a CMV vaccine or another CMV investigational agent, or is planning to participate in a study of a CMV vaccine or another CMV investigational agent during the course of this study.
• Is pregnant or expecting to conceive, is breastfeeding, or plans to breastfeed from the time of consent through 28 days after the last dose of study intervention.
• Is expecting to donate eggs starting from the time of consent through 28 days after the last dose of study intervention.
• Has clinically relevant drug or alcohol abuse within 12 months of screening that may interfere with participant treatment, assessment, or compliance with the protocol, as assessed by the investigator.

• Each patient must meet the following criteria to be enrolled in this study. 1. Be able to and provide written informed consent and be willing and able to comply with all study procedures 2. Adult, 18 years and older 3. AL amyloidosis Mayo stage IIIb based on the 2013 European Modification of the 2004 Standard Mayo Clinic Staging in patients with advanced cardiac involvement at the time of Screening 4. Measurable hematologic disease at Screening as defined by at least one of the following: 1. Involved/Uninvolved Free Light Chain Difference (dFLC) > 4 mg/dL or 2. Involved Free Light Chain (iFLC) > 4 mg/dL with abnormal ratio or 3. Serum Protein Electrophoresis (SPEP) m-spike > 0.5 g/dL 5. Histopathological diagnosis of amyloidosis AND confirmation of AL derived amyloid deposits by at least one of the following: 1. Immunohistochemistry or 2. Mass spectrometry or 3. Characteristic electron microscopy appearance 6. Cardiac involvement as defined by: a. Documented clinical signs and symptoms supportive of a diagnosis of heart failure in the setting of a confirmed diagnosis of AL amyloidosis in the absence of an alternative explanation for heart failure AND b. At least one of the following: i. Endomyocardial biopsy demonstrating AL cardiac amyloidosis or ii. Echocardiogram demonstrating a mean left ventricular wall thickness (calculated as [IVSd+LPWd]/2) of > 12 mm at diastole in the absence of other causes (e.g., severe hypertension, aortic stenosis), which would adequately explain the degree of wall thickening or iii. Cardiac MRI with gadolinium contrast agent diagnostic or cardiac amyloidosis 7. Planned first-line treatment for plasma cell disorder is a CyBorD-based regimen administered as Standard of Care (SoC) 8. Adequate bone marrow reserve and hepatic function as demonstrated by: 1. Absolute neutrophil count ≥ 1.0 x 109/L 2. Platelet count ≥ 75 x 109/L 3. Hemoglobin ≥ 9 g/dL 4. Total direct bilirubin ≤ 2 times the upper limit of normal (x ULN) unless due to Gilbert's syndrome. 5. Aspartate aminotransferase (AST) ≤ 3 x ULN 6. Alanine aminotransferase (ALT) ≤ 3 x ULN 7. Alkaline phosphatase (ALP) ≤ 5 x ULN (except for patients with hepatomegaly and isozymes specific to liver, rather than bone) 9. Women of childbearing potential (WOCBP) must have a negative pregnancy test during Screening and must agree to use highly effective physician approved contraception from Screening to at least 5 months following the last study drug administration or 12 months following the last dose of her PCD therapy, whichever is longer 10. Men must be surgically sterile or must agree to use effective physician approved contraception and refrain from donating sperm from Screening to at least 5 months following the last study drug administration or 12 months following the last dose of his PCD therapy, whichever is longer.
• Patients who meet any of the following criteria will not be permitted entry to the study. 1. Have any other form of amyloidosis other than AL amyloidosis 2. Received prior therapy for AL amyloidosis or multiple myeloma. A maximum exposure of 2 weeks of a CyBorD-based PCD treatment after screening laboratory samples are obtained and prior to randomization is allowed. 3. Has POEMS syndrome or multiple myeloma defined as clonal bone marrow plasma cells > 10% or biopsy-proven bony or extramedullary plasmacytoma AND any one or more of the following CRAB features: a. Evidence of end organ damage that can be attributed to the underlying plasma cell proliferative disorder, specifically: i. Hypercalcemia: serum calcium > 0.25 mmol/L (> 1mg/dL) higher than the ULN or > 2.75 mmol/L (> 11mg/dL) ii. Renal insufficiency: creatinine clearance < 40 mL per minute or serum creatinine > 177mol/L (> 2mg/dL) iii. Anemia: hemoglobin value of > 20g/L below the lowest limit of normal, or a hemoglobin value < 100g/L iv. Bone lesions: one or more osteolytic lesion on skeletal radiography, CT, or PET/CT. If bone marrow has < 10% clonal plasma cells, more than one bone lesion is required to distinguish from solitary plasmacytoma with minimal marrow involvement OR b. Any one of the following biomarkers of malignancy: i. 60% or greater clonal plasma cells on bone marrow examination ii. More than one focal lesion on MRI that is at least 5mm or greater in size 4. Have supine systolic blood pressure < 90 mmHg or symptomatic orthostatic hypotension, defined as a decrease in systolic blood pressure upon standing of > 30 mmHg despite medical management (e.g., midodrine, fludrocortisones) in the absence of volume depletion 5. Taking prednisone or its equivalent > 10 mg/day 6. Taking doxycycline 7. Receiving dialysis 8. Planned stem cell transplant during the first 6 months of protocol therapy. Stem cell collection during the protocol therapy is permitted. 9. Have had myocardial infarction, uncontrolled angina, severe uncontrolled ventricular arrhythmias within 6 months prior to screening or percutaneous cardiac intervention with recent stent or coronary artery bypass grafting within 4 months prior to screening. Exacerbation of chronic condition or new acute condition will require discussion and approval by the Medical Monitor. 10. Left Ventricular Ejection Fraction (LVEF) is < 40% by echocardiogram at Screening 11. Have severe valvular stenosis (e.g., aortic or mitral stenosis with a valve area < 1.0 cm2) or severe congenital heart disease 12. Have history of sustained ventricular tachycardia or aborted ventricular fibrillation or a history of atrioventricular nodal or sinoatrial nodal dysfunction for which a pacemaker/implantable cardioverter-defibrillator (ICD) is indicated but not placed. (Participants who do have a pacemaker or ICD are allowed in the study.) 13. QT corrected by Fridericia (QTcF) is > 550 msec. Participants who have a pacemaker may be included regardless of calculated QTc interval. 14. There is evidence of acute ischemia or active conduction system abnormalities with the exception of any of the following: 1. First degree Atrioventricular (AV)-block 2. Second degree AV-block Type 1 (Mobitz Type 1/Wenckebach type) 3. Right or left bundle branch block 4. Atrial fibrillation with a controlled ventricular rate. (An uncontrolled ventricular rate [i.e., > 110 beats per minute] determined by an average of three beats in lead II or representative beats in lead II is not allowed) 15. Have had major surgery within 4 weeks of randomization or is planning major surgery during the study. Patients with surgical procedures conducted under local anesthesia may participate 16. There is active malignancy (including lymphoma) with the exception of any of the following: 1. Adequately treated basal cell carcinoma, squamous cell carcinoma, or in situ cervical cancer 2. Adequately treated stage I cancer from which the patient is currently in remission and has been in remission for > 2 years 3. Low-risk prostate cancer with Gleason score < 7 and prostate-specific antigen < 10 mg/mL 4. Other localized and/or low risk malignancies may be permitted with Medical Monitor approval. 17. Have received an investigational drug/device in another clinical investigational study within 60 days before Screening 18. Hypersensitivity to the study drug 19. Have received a live vaccine within 4 weeks prior to first dose of CyBorD 20. Women who are breast feeding 21. Have any other medical, social or psychological factors that could affect the patient's safety or ability to consent personally or comply with study procedures.