• Patients must have a histopathologically confirmed diagnosis of an aggressive B-cell non-Hodgkin lymphoma that is recurrent or refractory to standard therapy
• For the purpose of this study, aggressive B-cell NHL will be deemed any lymphoma belonging to one of the following groups according to the 2016 revision of the World Health Organization (WHO) classification of lymphoid neoplasms
• For the purposes of stratification, diagnoses are grouped into 2 categories:
• Category A
• Burkitt lymphoma
• Burkitt-like lymphoma with 11q aberration
• High-grade B-cell lymphoma, with MYC and BCL2 and/or BCL6 rearrangements
• High-grade B-cell lymphoma, not otherwise specified (NOS)
• Category B
• Diffuse large B-cell lymphoma (DLBCL), NOS
• Diffuse large B-cell lymphoma (DLBCL), NOS; germinal center B-cell type
• Diffuse large B-cell lymphoma (DLBCL), NOS; activated B-cell type
• Large B-cell lymphoma with IRF4 rearrangement
• T-cell/histiocyte-rich large B-cell lymphoma
• Primary DLBCL of the central nervous system (CNS)
• Primary cutaneous DLBCL, leg type
• Epstein-Barr virus (EBV)+ DLBCL, NOS
• EBV+ mucocutaneous ulcer
• DLBCL associated with chronic inflammation
• Lymphomatoid granulomatosis
• Primary mediastinal (thymic) large B-cell lymphoma
• Intravascular large B-cell lymphoma
• ALK+ large B-cell lymphoma
• Plasmablastic lymphoma
• Primary effusion lymphoma
• Human herpesvirus (HHV)-8+ DLBCL, NOS
• B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and classical Hodgkin lymphoma
• Patients must have measurable disease, defined as at least one lesion that is > 15 mm (1.5 cm) in the longest axis on cross-sectional imaging and measurable in two perpendicular dimensions per computed tomography (spiral computed tomography [CT]), positron emission tomography (PET)-CT or magnetic resonance imaging (MRI)
• Patients must have disease that has relapsed after or is refractory to at least 2 lines of standard therapy; the remaining standard treatment options are unlikely to be effective in the opinion of the treating physician, or patient is felt to be ineligible for such therapies or the patient refuses such therapies; patients who have undergone autologous stem cell transplant are eligible as long as they meet all other criteria
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• Life expectancy of greater than 12 weeks
• White blood cell (WBC) >= 2000/mm^3 (within 14 days of registration)
• Absolute neutrophil count (ANC) >= 1500/mm^3 (within 14 days of registration)
• Platelet count >= 100,000/mm^3 (within 14 days of registration)
• Hemoglobin > 9.0 g/dL (within 14 days of registration)
• Total bilirubin =< 1.5 x upper limit of normal (ULN) (except patients with Gilbert Syndrome, who can have total bilirubin < 3.0 mg/dL) (within 14 days of registration)
• Aspartate transaminase (aspartate aminotransferase [AST]) =< 2.5 x ULN (within 14 days of registration)
• Calculated creatinine clearance (CrCl) >= 50 mL/min (if using the Cockcroft-Gault formula) (within 14 days of registration)
• Females of child bearing potential must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of human chorionic gonadotropin [HCG])
• Ability to understand and the willingness to sign a written informed consent document
• Patient has received chemotherapy, targeted agent, or radiotherapy within 4 weeks or at least 5 half-lives, whichever is longer, prior to registration
• Palliative (limited-field) radiation therapy is permitted, if all of the following criteria are met:
• Repeat imaging demonstrates no new sites of bone metastases
• The lesion being considered for palliative radiation is not a target lesion
• Patient has received immunotherapy (including monoclonal antibodies) within 4 weeks prior to registration
• Patients who have not recovered to grade 1 or less from any adverse events due to agents administered more than 4 weeks earlier (excluding alopecia)
• Patients who are receiving any other investigational agents
• Patients should be excluded if they have had prior treatment with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CTLA-4 antibody, or any other antibody or drug specifically targeting T-cell co-stimulation or immune checkpoint pathways
• Patients who have received autologous stem cell transplant (ASCT) =< 12 weeks prior to the first dose of study drug
• Patients with a prior history of allogeneic stem cell or solid organ transplantation
• Patients with evidence of active disease in the central nervous system (CNS) defined as either the presence of active lesions on MRI obtained within 4 weeks of registration or progressive neurological decline
• Patients with primary CNS lymphoma who develop systemic recurrence following standard therapy may be included as long as no active CNS disease is present at the time or enrollment; similarly, patients with secondary involvement of the CNS from a systemic lymphoma may be included as long as the CNS disease has been optimally treated and they demonstrate no evidence of active CNS disease
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to CDX-1127 (varlilumab) and/or nivolumab
• History of severe hypersensitivity reaction to any monoclonal antibody
• 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 would limit compliance with study requirements
• Pregnant women are excluded from this study because CDX-1127 (varlilumab) and nivolumab are agents with the 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 CDX-1127 (varlilumab) or nivolumab, breastfeeding should be discontinued if the mother is treated with CDX-1127 (varlilumab) or nivolumab
• Patients with human immunodeficiency virus (HIV) are eligible for the study provided they meet the other protocol criteria in addition to the following:
• Undetectable HIV load by standard polymerase chain reaction (PCR) clinical assay within 60 days prior to registration
• Absolute CD4 count of >= 200 mm^3 within 60 days prior to registration
• Willing to maintain adherence to combination antiretroviral therapy
• No history of acquired immunodeficiency syndrome (AIDS) defining condition (other than lymphoma or CD4 cell count < 200 mm^3)
• Likely to have near normal lifespan if not for the presence of relapsed/refractory lymphoma
• Patients with evidence of hepatitis B virus (HBV) are eligible provided there is minimal hepatic injury and the patient has undetectable HBV on suppressive HBV therapy; patient must be willing to maintain adherence to HBV therapy
• Patients with previously treated and eradicated hepatitis C virus (HCV) who have minimal hepatic injury are eligible
• Patients with active autoimmune disease or history of autoimmune disease that might recur, which may affect vital organ function or require immune suppressive treatment including systemic corticosteroids, should be excluded; these include but are not limited to patients with a history of immune related neurologic disease, multiple sclerosis, autoimmune (demyelinating) neuropathy, Guillain-Barre syndrome, myasthenia gravis; systemic autoimmune disease such as systemic lupus erythematosus (SLE), connective tissue diseases, scleroderma, inflammatory bowel disease (IBD), Crohn's, ulcerative colitis, hepatitis; and patients with a history of toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome, or phospholipid syndrome should be excluded because of the risk of recurrence or exacerbation of disease; patients with vitiligo, endocrine deficiencies including thyroiditis managed with replacement hormones including physiologic corticosteroids are eligible; patients with rheumatoid arthritis and other arthropathies, Sjogren's syndrome and psoriasis controlled with topical medication and patients with positive serology, such as antinuclear antibodies (ANA), anti-thyroid antibodies should be evaluated for the presence of target organ involvement and potential need for systemic treatment but should otherwise be eligible
• Patients 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 (precipitating event)
• 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; patients are permitted to use topical, ocular, intra-articular, intranasal, and inhalational corticosteroids (with minimal systemic absorption); physiologic replacement doses of systemic corticosteroids are permitted, even if =< 10 mg/day prednisone equivalents; a brief course of corticosteroids for prophylaxis (e.g., contrast dye allergy) or for treatment of non-autoimmune conditions (e.g., delayed-type hypersensitivity reaction caused by contact allergen) is permitted
• Patients who have had evidence of active or acute diverticulitis, intra-abdominal abscess, gastrointestinal (GI) obstruction and abdominal carcinomatosis which are known risk factors for bowel perforation should be evaluated for the potential need for additional treatment before coming on study
• Patients with other active malignancy =< 3 years prior to registration for which active treatment is required must be excluded; patients with composite lymphomas that have a non-B-cell component must be excluded EXCEPTIONS: Non-melanotic skin cancer or carcinoma-in-situ of the cervix

• All B-ALL patients must be enrolled on APEC14B1 and consented to Eligibility Screening (Part A) prior to treatment and enrollment on AALL1731. APEC 14B1 is not a requirement for B-LLy patients. B-LLy patients may directly enroll on AALL1731 and MUST submit eligibility studies.
• Age at diagnosis:
• Patients must be >= 365 days and < 10 years of age (B-ALL patients without DS).
• Patients must be >= 365 days and =< 31 years of age (B-ALL patients with DS).
• Patients must be >= 365 days and =< 31 years of age (B-LLy patients with or without DS).
• B-ALL patients without DS must have an initial white blood cell count < 50,000/uL (performed within 7 days prior to enrollment).
• B-ALL patients with DS are eligible regardless of the presenting white blood cell count (WBC) (performed within 7 days prior to enrollment).
• Patient has newly diagnosed B-cell ALL, with or without Down syndrome: > 25% blasts on a bone marrow (BM) aspirate;
• OR if a BM aspirate is not obtained or is not diagnostic of B-ALL, the diagnosis can be established by a pathologic diagnosis of B-ALL on a BM biopsy;
• OR a complete blood count (CBC) documenting the presence of at least 1,000/uL circulating leukemic cells;
• OR patient has newly diagnosed B-cell LLy Murphy stages I or II, with or without Down syndrome.
• Note: For B-LLy patients with tissue available for flow cytometry, the criterion for diagnosis should be analogous to B-ALL. For tissue processed by other means (i.e., paraffin blocks), the methodology and criteria for immunophenotypic analysis to establish the diagnosis of B-LLy defined by the submitting institution will be accepted (diagnostic biopsy for B-LLy must be performed within 14 days prior to enrollment).
• All institutional, Food and Drug Administration (FDA), and National Cancer Institute (NCI) requirements for human studies must be met.
• All patients and/or their parents or legal guardians must sign a written informed consent.
• Patient must not have secondary ALL that developed after treatment of a prior malignancy with cytotoxic chemotherapy. Note: patients with Down syndrome with a prior history of transient myeloproliferative disease (TMD) are not considered to have had a prior malignancy. They would therefore be eligible whether or not the TMD was treated with cytarabine.
• With the exception of steroid pretreatment or the administration of intrathecal cytarabine, patients must not have received any prior cytotoxic chemotherapy for either the current diagnosis of B ALL or B LLy or for any cancer diagnosed prior to initiation of protocol therapy on AALL1731.
• For patients receiving steroid pretreatment, the following additional exclusion criteria apply:
• Non-DS B-ALL patients must not have received steroids for more than 24 hours in the 2 weeks prior to diagnosis without a CBC obtained within 3 days prior to initiation of the steroids.
• DS and non-DS B-LLy patients must not have received > 48 hours of oral or IV steroids within 4 weeks of diagnosis.
• B-ALL patients who do not have sufficient diagnostic bone marrow submitted for APEC14B1 diagnostic testing and who do not have a peripheral blood sample submitted containing > 1,000/uL circulating leukemia cells.
• Patient must not have acute undifferentiated leukemia (AUL).
• Non-DS B-ALL patients with central nervous system [CNS]3 leukemia (CNS status must be known prior to enrollment).
• Note: DS patients with CNS3 disease are eligible but will be assigned to the DS-High B-ALL arm. CNS status must be determined based on a sample obtained prior to administration of any systemic or intrathecal chemotherapy, except for steroid pretreatment.
• Non-DS B-ALL patients with testicular leukemia. (Note: DS patients with testicular disease are eligible but will be assigned to the DS-High B-ALL arm).
• For LLy patients, the following additional exclusion criteria apply:
• T-Lymphoblastic Lymphoma.
• Morphologically unclassifiable lymphoma.
• Absence of both B-cell and T-cell phenotype markers in a case submitted as lymphoblastic lymphoma.
• CNS positive disease or testicular involvement.
• M2 (5%
•25% blasts) or M3 (> 25% blasts) marrow.
• Patients with known Charcot-Marie-Tooth disease.
• Patients with evidence of a MYC translocation associated with mature (Burkitt) B-cell ALL, regardless of blast immunophenotype.
• 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.

1. Signed informed consent. Consent must be obtained prior to any study-related procedure. 2. Age ≥ 18 years 3. Histologically confirmed AML or MDS: 1. AML
•relapsed or refractory AML and refuses or is not a candidate for intensive chemotherapy (due to prior failure or not eligible due to expected intolerance) or allogeneic transplant 2. MDS
•relapsed or refractory MDS with > 5% blasts in the marrow or any blasts in the peripheral blood. Patients must have failed prior treatment with an HMA (azacitidine, decitabine, or other HMA agent); failure is defined as intolerance to HMA, lack of response [no complete remission (CR) by at least 6 cycles], or have IWG-defined progressive disease during or after treatment with an HMA. 4. Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2 5. Life expectancy of > 2 months in the Investigator's opinion 6. White blood cells (WBC) ≤ 25,000 cells/mm3 (may receive hydroxyurea to bring WBC count down prior to and during the first cycle of treatment with study drug if necessary) 7. Creatinine ≤ 2 × upper limit of normal (ULN) 8. Adequate liver test parameters: total bilirubin < 2.5 × ULN (if disease related or secondary to Gilbert's disease, then total bilirubin < 3.5 mg/dL), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) < 3 × ULN 9. Prothrombin time (PT) / international normalized ratio (INR) and partial thromboplastin time (PTT) < 1.5 × ULN 10. Patients and partners of childbearing potential must be willing to use adequate contraception during the study and for 2 months after last study drug administration. Adequate contraception means less than 1% chance of pregnancy may occur with proper use of the method(s). 1. Any central nervous system (CNS) (cerebral/meningeal) disease related to underlying malignancy 2. History of seizures 3. Acute promyelocytic leukemia 4. Prior anti-CD123 therapy outside of this study 5. Any clinically significant graft-versus-host disease (GVHD) secondary to prior allogenic transplant. Patients must be >90 days from transplant and have been on no immunosuppressive therapy for >30 days. Topical corticosteroids for minor skin rash (<5% body surface area) is acceptable. Prior solid organ transplant is acceptable provided the patient is on no immunosuppressive therapy. 6. Any therapy or experimental treatment for MDS or AML within 7 days of the first dose of study drug. Must have recovered to Grade ≤ 1 from any Grade 2 to 4 toxicity from previous treatment. The use of hydroxyurea is acceptable and does not exclude the patient. 7. Active, uncontrolled infection requiring systemic therapy. If the infection is controlled or has resolved, maintenance and/or prophylactic systemic antimicrobials are permitted. 8. Major surgery within 3 weeks prior to first dose of study drug 9. Known to be positive for HIV, hepatitis B virus surface antigen (HBsAg), hepatitis B core antibody (HBcAb), or hepatitis C virus (HCV) 10. Pregnant or breast feeding 11. Any other active systemic malignancies. Exceptions: noninvasive non-melanoma skin cancer, in situ carcinoma, cervical intraepithelial neoplasia, and breast or prostate cancer that is well controlled with anti-hormonal therapy 12. Any current autoimmune disorder requiring immunosuppressive therapy 13. Requires more than a replacement dose of corticosteroids (i.e., > 10 mg/day of prednisone or equivalent) 14. Any uncontrolled medical condition, including but not limited to: 1. Symptomatic congestive heart failure ≥ Class III (New York Heart Association Functional Classification) 2. Uncontrolled hypertension 3. Unstable angina 4. Myocardial infarction within previous 6 months 5. Clinically significant arrhythmias not controlled by medication 6. Uncontrolled metabolic disorders such as hypercalcemia 15. Substance use disorder, psychiatric, cognitive, or any other condition that, in the opinion of the Investigator, would pose a risk to the patient's safety, may compromise the patient's ability to understand and comply with the protocol or provide informed consent, or interfere with the study evaluation 16. Any difficulty complying with protocol requirements that may increase the risk associated with study participation or study drug administration, or may cause a safety concern for the patient

• Man or woman greater than or equal to (>=) 18 years of age
• In Part 1, diagnosis of myelodysplastic syndrome (MDS) according to World Health Organization (WHO) criteria
• International Prognostic Scoring System (IPSS) low Risk or intermediate-1 risk MDS
• Red blood cell (RBC) transfusion dependent, defined as requiring at least 4 RBC units transfused over an 8-week period during the 16 weeks prior to Study Entry; pre-transfusion hemoglobin (Hb) should be less than or equal to 9.0 gram per deciliter (g/dL) to count towards the 4 units total
• Eastern Cooperative Oncology Group (ECOG) performance status 0, 1 or 2
• Participant has known allergies, hypersensitivity, or intolerance to imetelstat or its excipients
• Participant has received an investigational drug or used an invasive investigational medical device within 30 days prior to Study Entry or is currently enrolled in an investigational study
• Prior treatment with imetelstat
• Have received corticosteroids greater than (>) 30 milligram per day (mg/day) prednisone or equivalent, or growth factor treatment within 4 weeks prior to study entry
• a) Prior treatment with a hypomethylating agent (example [eg], azacitidine, decitabine); b) Prior treatment with lenalidomide; c) Has received an erythropoiesis-stimulating agent (ESA) or any chemotherapy, immunomodulatory, or immunosuppressive therapy within 4 weeks prior to study entry (8 weeks for long-acting ESAs)

Key 1. Age 21 years or younger at the time of initial ALL diagnosis and age > 1 year at the time of study treatment initiation. 2. Subjects must have a diagnosis of relapsed or refractory ALL with ≥ 5% blasts in the bone marrow (M2 or M3 disease), with or without extramedullary disease. a. To be eligible, subjects must have had 1 or more prior therapeutic attempts, defined as:
• Early first relapse (< 36 months from original diagnosis) after achieving a CR (B-ALL) or first relapse any time following the original diagnosis after achieving a CR (T-ALL)
• First refractory bone marrow relapse occurring any time after original diagnosis after achieving a CR (ie, ≥1 failed attempt to induce a second remission) OR
• Relapse after achieving a CR following the first or subsequent relapse (i.e., ≥ 2 relapses) OR
• Failing to achieve a CR from original diagnosis after at least 1 induction attempt 3. Subjects must have fully recovered from the acute toxic effects of all previous chemotherapy, immunotherapy, or radiotherapy treatment before enrollment. 4. Subjects must have a serum creatinine level that is ≤ 1.5 × institutional upper limit of normal (ULN) according to age. If serum creatinine level is > 1.5 × ULN, the subject must have a calculated creatinine clearance or radioisotope glomerular filtration rate (GFR) ≥ 70 mL/min/1.73 m2, or for children<2 years of age, ≥ 50mL/min/1.73 m2. 5. Adequate liver function, defined as both of the following: 1. Total bilirubin ≤ 1.5 × institutional ULN except in the presence of Gilbert Syndrome 2. Alanine aminotransferase (ALT) ≤ 5 × institutional ULN 6. Performance status: Karnofsky or Lansky scores ≥ 50 for subjects > 16 years old or ≤ 16 years old, respectively. Key 1. Known allergy to any of the drugs used in the study. (Subjects who have had a previous allergy to PEG-asparaginase are eligible and if able, may receive Erwinia asparaginase at the investigator's discretion.) 2. Known allergy to Captisol (a cyclodextrin derivative used to solubilize carfilzomib) 3. Left ventricular fractional shortening < 30% 4. History of ≥ Grade 2 pancreatitis 5. Active graft‑versus‑host disease requiring systemic treatment 6. Positive culture for or other clinical evidence of infection with bacteria or fungus within 14 days of the initiation of study treatment 7. Down Syndrome 8. Prior therapy restrictions: 1. Subjects must have completed therapy with granulocyte‑colony stimulating factor (G‑CSF) or other myeloid growth factors at least 7 days before study treatment initiation, or at least 14 days before study treatment initiation, if pegylated myeloid growth factors were administered. 2. Subjects must have completed any type of active immunotherapy (e.g., tumor vaccines) at least 42 days before study treatment initiation. 3. Subjects must have received the last dose of a non-monoclonal antibody biologic agent at least 7 days before study treatment initiation. 4. At least 3 antibody half‑lives must have elapsed since the last dose of monoclonal antibody (e.g., 66 days for rituximab, 69 days for epratuzumab and 36 days for inotuzumab) before subjects may initiate study treatment. 5. Subjects must not have received other antineoplastic agents with therapeutic intent, excluding hydroxyurea and antimetabolites administered as part of maintenance chemotherapy, within 7 days prior to study treatment initiation 9. Hepatitis B infection with positive hepatitis B DNA

Subjects must satisfy the following criteria to be enrolled in the study: 1. Subject is ≥ 18 years of age at the time of signing the informed consent form (ICF) 2. Subject has measurable disease, defined as:
• M-protein (serum protein electrophoresis [sPEP] or urine protein electrophoresis [uPEP]): sPEP ≥ 0.5 g/dL or uPEP ≥ 200 mg/24 hours and/or
• Light chain MM without measurable disease in the serum or urine: Serum immunoglobulin free light chain ≥ 10 mg/dL and abnormal serum immunoglobulin kappa lambda free light chain ratio 3. Subjects with one of the following cohort specific requirements: Cohort 1 RRMM subjects with ≥ 3 prior anti-myeloma treatment regimens:
• Subject must have received at least 3 prior anti-myeloma treatment regimens. Note: induction with or without hematopoietic stem cell transplant and with or without maintenance therapy is considered a single regimen
• Subject must have undergone at least 2 consecutive cycles of treatment for each regimen, unless PD was the best response to the regimen
• Subject must have received prior treatment with a proteasome inhibitor, an immunomodulatory agent and an anti-CD38 antibody
• Subject has evidence of PD on or within 60 days of the most recent prior treatment regimen
• Subject achieved a response (minimal response [MR] or better) to at least 1 prior treatment regimen Cohort 2 subjects with 1 prior anti-myeloma treatment regimen:
• Subject must have received only 1 prior anti-myeloma treatment regimen. Note: induction with or without hematopoietic stem cell transplant and with or without maintenance therapy is considered a single regimen
• Subject must have the following HR factors:
•R-ISS stage III AND
• Early relapse defined as: Cohort 2a: PD < 18 months since date of start of initial therapy. Initial therapy must contain induction, ASCT (single or tandem) and lenalidomide containing maintenance. Cohort 2b: PD < 18 months since date of start or initial therapy which must contain at minimum, a proteasome inhibitor, an immunomodulatory agent and dexamethasone Cohort 2c: Subject must have received minimum 3 cycles of induction therapy which must contain at minimum, a proteasome inhibitor, an immunomodulatory agent and dexamethasone. Subjects must have had ASCT (single or tandem AND < VGPR (excluding PD) at first assessment between 70 to 110 days after last ASCT, with initial therapy without consolidation and maintenance. 4. Subject must have Eastern Cooperative Oncology Group (ECOG) performance status ≤ 1 5. Subject must have recovery to Grade 1 or baseline of any non-hematologic toxicities due to prior treatments, excluding alopecia and Grade 2 neuropathy The presence of any of the following will exclude a subject from enrollment: 1. Subject used any investigational agents within 14 days of leukapheresis 2. Subject received any of the following within the last 14 days of leukapheresis: 1. Plasmapheresis 2. Major surgery (as defined by the investigator) 3. Radiation therapy other than local therapy for myeloma associated bone lesions 4. Use of any systemic anti-myeloma drug therapy 3. Subject with known central nervous system involvement with myeloma 4. Subject has clinical evidence of pulmonary leukostasis and disseminated intravascular coagulation 5. History or presence of clinically relevant central nervous system (CNS) pathology 6. Subject with active or history of plasma cell leukemia, Waldenstrom's macroglobulinemia, POEMS syndrome, or clinically significant amyloidosis 7. Inadequate organ function Subject with a history of Class III or IV congestive heart failure (CHF) or severe nonischemic cardiomyopathy, unstable or poorly controlled angina, myocardial infarction, or ventricular arrhythmia within the previous 6 months prior to starting study treatment 8. Ongoing treatment with chronic immunosuppressants 9. Previous history of an allogeneic hematopoietic stem cell transplantation or treatment with any gene therapy-based therapeutic for cancer or investigational cellular therapy for cancer or BCMA targeted therapy 10. Subject has received ASCT within 12 weeks prior to leukapheresis 11. Subject has history of primary immunodeficiency 12. Subject is positive for human immunodeficiency virus (HIV-1), chronic or active hepatitis B or active hepatitis A or C 13. Subject has uncontrolled systemic fungal, bacterial, viral or other infection (including tuberculosis) despite appropriate antibiotics or other treatment 14. Subject with prior history of malignancies, other than MM, unless the subject has been free of the disease for ≥ 5 years 15. Pregnant or lactating women 16. Subject with known hypersensitivity to any component of bb2121 product, cyclophosphamide, fludarabine, and/or tocilizumab

1. Pediatric and adult patients with a diagnosis of ALL or LBL. 2. Have had an allergic reaction to a long-acting E. coli-derived asparaginase OR have silent inactivation. 3. Have 1 or more courses of E. coli-derived asparaginase remaining in his/her treatment plan. 4. Patients must have, in the opinion of the Investigator, fully recovered from their prior allergic reaction to E. coli-derived asparaginase. 1. Have previously received asparaginase Erwinia chrysanthemi or JZP-458. 2. Have relapsed ALL or LBL. 3. Are concurrently receiving another investigational agent and/or treated with an investigational device at the same time as JZP-458 (within 48 hours) during Course 1 of JZP-458. 4. Have a history of ≥ Grade 3 pancreatitis. 5. Prior history of asparaginase-associated ≥ Grade 3 hemorrhagic event or asparaginase-associated thrombus requiring anticoagulation therapy, excluding catheter-related thrombotic events.

Inclusion Criteria Age -Patients must be ≥ 1 and ≤ 21 years of age at the time of enrollment. Diagnosis
• Cohort A: Patients must have a diagnosis of acute lymphoblastic leukemia (ALL) or mixed phenotypic acute leukemia with ≥ 5% blasts in the bone marrow (M2 or M3), with or without extramedullary disease) or a diagnosis of lymphoblastic lymphoma.
• Cohorts B & C: Patients must have a diagnosis of acute lymphoblastic leukemia (ALL), lymphoblastic lymphoma, or mixed phenotypic acute leukemia with any level of detectable disease (minimal residual disease level acceptable) with or without extramedullary disease Performance Level -Karnofsky > 50% for patients > 16 years of age and Lansky > 50% for patients ≤ 16 years of age. Prior Therapy
• Patients must have recovered from the acute toxic effects (≤ Grade 2 or baseline) of all prior chemotherapy, immunotherapy, or radiotherapy prior to entering this study, unless otherwise specified. Subjects with disease related cytopenias will be eligible.
• Patients must have relapsed or refractory disease after attaining at least a first remission. They may be in first to third relapse..
• Patients with Philadelphia chromosome t(9;22) positive disease must have received at least two prior tyrosine kinase inhibitors.
• Patients who have experienced their relapse after a Hematopoietic stem cell transplantation (HSCT) are eligible, provided they have no evidence of graft-versus-host disease (GVHD) and are at least 100 days post-transplant at the time of enrollment.
• Prior anthracycline lifetime cumulative exposure: Patients must have less than 320 mg/m2 (or 400 mg/m2 if prior cardioprotection) lifetime exposure of anthracycline chemotherapy. 1. Cohort A: Patients must have less than 320 mg/m2 (or 400 mg/m2 if prior cardioprotection) lifetime exposure of anthracycline chemotherapy (See Appendix 2 for anthracycline calculation worksheet). 2. Cohorts B & C: There is no limit on prior anthracycline exposure.
• Hematopoietic growth factors: It must have been at least seven days since the completion of therapy with granulocyte colony-stimulating factor (GCSF) or other growth factors at the time of enrollment. It must have been at least 14 days since the completion of therapy with pegfilgrastim (Neulasta®).
• Biologic anti-neoplastic agents: At least seven days after the last dose of a biologic agent. For agents that have known adverse events occurring beyond seven days after administration, this period must be extended beyond the time during which adverse events are known to occur. The duration of this interval must be discussed with the study chair or vice chair.
• Monoclonal antibodies: At least three half-lives (or 30 days—whichever is longer) of the antibody must have elapsed after the last dose of monoclonal antibody. (e.g., Rituximab = 66 days, Epratuzumab = 69 days)
• Immunotherapy: At least 30 days after the completion of any type of immunotherapy, e.g. tumor vaccines, chimeric antigen receptor T-cells.
• Recent prior chemotherapy: At least 10 days after standard vincristine and the completion of any type of chemotherapy induction regimen. At least 3 weeks after radiation therapy. At least 30 days after the completion of any investigational neoplastic agent is also required. An investigational agent is defined as any drug that is not approved and licensed for sale by the FDA for institutions in the United States, by Health Canada for institutions in Canada and by The Therapeutic Goods Administration for institutions in Australia. Exceptions:
• There is no time restriction in regard to prior intrathecal chemotherapy provided there is complete recovery from any acute toxic effects of such; it is allowable to enroll a patient that has received IT Cytarabine (ARA-C), IT Methotrexate (MTX) or triple IT therapy within 14 days of enrollment as part of their evaluation to diagnose disease relapse. The IT therapy given within 14 days of initiation of protocol specified chemotherapy, may substitute for the day 1 IT in cohorts A and B
• Subjects with rapidly progressive disease may receive hydroxyurea until they begin study therapy;
• Patients who relapse while on maintenance-type ALL therapy or are receiving maintenance therapy for disease stabilization will not require a wash-out period before entry into this study. However, there must be at least 10 days after any dose of standard vincristine. Renal and Hepatic Function
• Renal function: Patient's serum creatinine must be ≤ 1.5 x institutional upper limit of normal (ULN) according to age. If the serum creatinine is greater than 1.5 times normal, the patient must have a calculated creatinine clearance or radioisotope glomerular filtration rate (GFR) ≥ 70milliliter/min/1.73m2. Alternatively, a 24-hour creatinine clearance may also be used.
• Hepatic function: alanine aminotransferase (ALT) and aspartate aminotransferase (AST) must be < 5 x institutional upper limit of norm ULN. Total bilirubin must be ≤ 1.5 x ULN (except in the case of subjects with documented Gilbert's disease ≤ 5 × ULN). Cardiac Function -Patients must have a shortening fraction ≥ 27% or an ejection fraction ≥ 55% by echocardiogram, cardiac MRI or multigated acquisition scan (MUGA). Reproductive Function
• Female patients must not be pregnant and those of childbearing potential must have a negative urine or serum pregnancy test confirmed within one week prior to enrollment.
• Female patients with infants must agree not to breastfeed their infants while on this study.
• Male and female patients of childbearing potential must agree to use an effective method of contraception during the study. Exclusion Criteria Patients will be excluded if they have isolated testicular disease. Patients will be excluded if they have previously received Marqibo®. Patients will be excluded if they have a known allergy to any of the drugs used in the study, with the exception that patients with an allergy to PEG-asparaginase who can receive Erwinia asparaginase are eligible. Patients unable to receive any formulation of asparaginase may only enroll on cohort C Patients will be excluded if they have active, uncontrolled systemic fungal, bacterial, viral or other infection despite appropriate antibiotics or other treatment. Patients who require azole antifungal agents will be excluded. Azoles must be discontinued at least one week prior to the start of Marqibo®. Patients will be excluded if there is a plan to administer non-protocol chemotherapy, radiation therapy, another investigational agent or immunotherapy during the study period. Patients with pre-existing, persistent grade 2 or greater sensory or motor neuropathy from any cause will be excluded. Patients will be excluded if they have, significant concurrent disease, illness, psychiatric disorder or social issue that would compromise patient safety or adherence with the protocol treatment or procedures or interfere with consent, study participation, follow up, or interpretation of study results.Patients with Down syndrome will not be eligible for enrollment on Cohort A Patients with a known history of human immunodeficiency virus (HIV) will will be excluded due to the increased risk of complications such as severe infection and unknown interaction of Marqibo® with antiretroviral drugs. Active hepatitis B or C infection as defined by seropositive for hepatitis B (hepatitis B surface antigen (HBsAg)) or hepatitis C and elevated liver transaminases (defined as above the ULN per the institution normal ranges).

• Patients must have constitutional trisomy 21 (Down syndrome) or trisomy 21 mosaicism (by karyotype or fluorescence in situ hybridization [FISH])
• Patient has one of the following:
• Patient has previously untreated de novo AML and meets the criteria for AML with >= 20% bone marrow blasts as set out in the World Health Organization (WHO) Myeloid Neoplasm classification
• Attempts to obtain bone marrow either by aspirate or biopsy must be made unless clinically prohibitive; in cases where it is clinically prohibitive, peripheral blood with an excess of 20% blasts and in which adequate flow cytometric and cytogenetics/FISH testing is feasible can be substituted for the marrow exam at diagnosis
• Patient has cytopenias and/or bone marrow blasts but does not meet the criteria for the diagnosis of AML (WHO Myeloid Neoplasm classification) because of < 20% marrow blasts and meets the criteria for a diagnosis of myelodysplastic syndrome (MDS)
• Patient has a history of transient myeloproliferative disorder (which may or may not have required chemotherapy intervention), who:
• Are > 8 weeks since resolution of transient myeloproliferative disease (TMD) with >= 5% blasts, OR
• Patients who have an increasing blast count (>= 5%) in serial bone marrow aspirates performed at least 4 weeks apart
• Children who have previously received chemotherapy, radiation therapy or any anti-leukemic therapy are not eligible for this protocol, with the exception of cytarabine for the treatment of TMD
• There are no minimal organ function requirements for enrollment on this study
• Note: Previous cardiac repair with sufficient cardiac function is not an exclusion criteria
• Each patient?s parents or legal guardians must sign a written informed consent
• All institutional, Food and Drug Administration (FDA), and National Cancer Institute (NCI) requirements for human subjects research must be met
• Patients with promyelocytic leukemia (French-American-British [FAB] M3)
• Prior therapy
• Patients =< 30 days from the last dose of cytarabine used for treatment of TMD

• Diagnosis of advanced solid tumor cancer, lymphoma, or myeloma (no time restrictions or limitations) -OR- diagnosis of early stage solid tumor cancer, lymphoma, or myeloma <= 12 months prior to study enrollment
• Diagnosis of VTE <= 30 days prior to study enrollment for which potential benefits of anticoagulation therapy to prevent recurrence of VTE are felt by the treating physician to exceed the potential harms
• Any anticoagulation drug/strategy may be used to treat the index VTE; protocol treatment will begin <= 30days after the index VTE diagnosis date
• Treating physician intends to put participant on anticoagulation therapy for at least three months.
• Age >= 18 years
• Platelet count is >= 50,000/mm^3 (<= 7 days prior to enrollment)
• CrCl (Creatinine Clearance) is >= 15 ml/min (<= 7 days prior to enrollment)
• Diagnosis of acute leukemia
• Has ever received or is scheduled to receive an Allogeneic Hematopoietic Stem Cell Transplantation (alloHSCT)
• Patients who have ever received an Autologous Hematopoietic Stem Cell Transplantation (autoHSCT) ARE eligible.
• Patients who are scheduled to receive an Autologous Hematopoietic Stem Cell Transplantation (autoHSCT) are NOT eligible
• Ongoing, clinically significant bleeding (CTCAE grade 3 or 4)
• Ongoing therapy with a P-gp inhibitor (e.g., nelfinavir, indinavir, or saquinavir-protease inhibitors for HIV) as these drugs interact with the factor Xa inhibitors
• Therapy with any azole antifungals (e.g., itraconazole, ketaconazole, voriconazole) at the time of enrollment

• Histologically confirmed pediatric mature B-cell non-Hodgkin lymphoma (B-cell NHL) including the following subtypes; Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL), primary mediastinal B-cell lymphoma (PMBCL), gray zone lymphoma (GZL), and follicular lymphoma (FL) Note: Patients with bone marrow involvement of >25% lymphoma cells by bone marrow biopsy/aspirate evaluation, will be excluded. Patients with B-cell NHL associated with Nijmegen breakage syndrome will be allowed.
• Patients <18 years of age and weighing at least 6 kg at the time of screening
• Patients who have relapsed after one or more prior therapies (can include allogeneic and autologous hematopoietic stem cell transplant) or are primary refractory (have not achieved a CR or PR after the first line of therapy)
• Measurable disease by radiological criteria in all patients at the time of screening.
• Karnofsky (age ≥16 years) or Lansky (age <16 years) performance status ≥60.
• Adequate bone marrow reserve without transfusions (transfusion >2 weeks prior to laboratory assessment is allowed) defined as: 1. Absolute neutrophil count (ANC) >1000/mm3 2. Absolute lymphocyte count (ALC) >300/mm3 3. absolute number of CD3+ T cells >150/mm3 4. Platelets ≥50000//mm3 5. Hemoglobin ≥8.0 g/dl
• Adequate organ function defined as: 1. a serum creatinine (sCR) based on gender/age as follows: Maximum Serum Creatinine (mg/dL) Age Male Female 1 to <2 years 0.6 0.6 2 to <6 years 0.8 0.8 6 to <10 years 1.0 1.0 10 to <13 years 1.2 1.2 13 to <16 years 1.5 1.4 ≥16 years 1.7 1.4 2. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤5 times the upper limit of normal (ULN) for age 3. Total bilirubin <2 mg/dL (for Gilbert's Syndrome patients total bilirubin <4 mg/dL) 4. Adequate pulmonary function i. Oxygen saturation of >91% on room air ii. No or mild dyspnea (≤Grade 1)
• Must have a leukapheresis material of non-mobilized cells accepted for manufacturing.
• Prior gene therapy or engineered T cell therapy.
• Prior treatment with any anti-CD19 therapy.
• Allogeneic hematopoietic stem cell transplant (HSCT) <3 months prior to screening and ≤4 months prior to infusion.
• Presence of grade 2 to 4 acute or extensive chronic graft-versus-host disease (GVHD) in patients who received prior allogeneic HSCT.
• Prior diagnosis of malignancy other than study indication, and not disease free for 5 years.
• Active, uncontrolled infection despite treatment at screening.
• Presence of active or prior hepatitis B or C as indicated by serology.
• Human Immunodeficiency Virus (HIV) positive test.
• Active neurological autoimmune or inflammatory disorders not related to B cell NHL (eg: Guillain-Barre syndrome, Amyotrophic Lateral Sclerosis)
• Active central nervous system (CNS) involvement by malignancy.
• Patients with B-cell NHL in the context of post-transplant lymphoproliferative disorders (PTLD) associated lymphomas. Other protocol-defined inclusion/exclusion criteria may apply.

1. Histologically or pathologically confirmed diagnosis of AML based on World Health Organization (WHO) classification that has relapsed after, or is refractory to, two or three prior induction regimens that may have included intensive chemotherapy (e.g., "7+3" cytarabine and daunorubicin), epigenetic therapy (i.e., azacitidine or decitabine) , or targeted therapy (e.g., FLT-3, IDH-1/2, BCL-2, monoclonal antibody). (Relapse is defined as reemergence of ≥5% leukemia blasts in bone marrow or ≥1% blasts in peripheral blood 90 days to 24 months after first CR or CR without complete platelet recovery (CRp). Refractory AML is defined as persistent disease ≥28 days after initiation of intensive induction therapy (up to two induction cycles) or relapse <90 days after first CR or CRp. Refractory disease for patients undergoing hypomethylating agent induction is defined as lack of remission following at least 2 cycles of epigenetic therapy without reduction in bone marrow blast status.) 2. Aged ≥ 18 years. 3. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1 or 2. 4. Adequate clinical laboratory values (i.e., plasma creatinine < 2.5 x upper limit of normal (ULN) for the institution, bilirubin < 2.5 x ULN, alanine transaminase (ALT) and aspartate transaminase (AST) ≤ 2.5 x ULN). 5. Absence of active central nervous system (CNS) involvement by leukemia. Patients with previously diagnosed CNS leukemia are eligible if the CNS leukemia is under control and intrathecal treatment may continue throughout the study. 6. Absence of uncontrolled intercurrent illnesses, including uncontrolled infections, cardiac conditions, or other organ dysfunctions. 7. Signed informed consent prior to the start of any study specific procedures. 8. Women of child-bearing potential must have a negative serum or urine pregnancy test. 9. Male and female patients must agree to use acceptable contraceptive methods for the duration of the study and for at least one month after the last drug administration. 1. The interval from prior treatment to time of study drug administration is < 2 weeks for cytotoxic agents or < 5 half-lives for noncytotoxic agents. Exceptions: Use of hydroxyurea is allowed before the start of study and is to be discontinued prior to randomization. Hydroxyurea may be administered before study start and up to the time of study randomization. At the investigator's discretion, for patients with significant leukocytosis during the early treatment cycles, hydroxyurea may be administered. The hydroxyurea should be discontinued as soon as clinically appropriate. 2. Any >grade 1 persistent clinically significant toxicities from prior chemotherapy. 3. Cardiac (left ventricular ejection fraction ≤40%) function. 4. White blood cell (WBC) >15,000/uL. 5. For patients with prior hematopoietic stem cell transplant (HSCT): 1. Less than 3 months since HSCT 2. Acute Graft versus Host Disease (GvHD) >Grade 1 3. Chronic GvHD >Grade 1 6. Any concomitant condition that in the opinion of the investigator could compromise the objectives of this study and the patient's compliance. 7. A pregnant or lactating woman. 8. Current malignancies of another type. Exceptions: Patients may participate if they have previously treated and currently controlled prostate cancer, or adequately treated in situ cervical cancer or basal cell skin cancer, or other malignancies with no evidence of disease for 2 years or more. 9. Patient has acute promyelocytic leukemia (APL). 10. Patients with known HIV, HBV or HCV infection (note: testing for these infections is not required). 11. Documented or known clinically significant bleeding disorder.

• Written assent (when applicable) and written informed consent by a legally authorized representative provided prior to participation in the study
• Age 2
•<18 years old
• CKD defined by eGFR <60 mL/min/1.73m2 including renal transplant, peritoneal dialysis
• Two potassium measurements of 5.1 to < 6.5 mEq/L performed on separate days
• In the opinion of the study doctor, is expected to require treatment for hyperkalemia for at least 6 months
• If taking any renin-angiotensin-aldosterone system inhibitors (RAASi) beta blockers or diuretic medications, must be on a stable dose for at least 28 days prior to Screening
• Negative pregnancy test in females of child-bearing potential
• False elevation in blood potassium (pseudohyperkalemia) due to hemolysis (breaking of blood cells) or abnormally high counts of blood cells at Screening
• Evidence of potassium-related electrocardiogram (ECG) changes at Screening
• Any of the following kidney conditions: hemodialysis, renal artery stenosis, and acute kidney injury or a history of acute renal insufficiency in the past 3 months
• Severe disorder of stomach or intestines including surgery
• Increased liver enzymes (ALT, AST > 3 times upper limit of normal) at Screening
• Active cancer, currently on cancer treatment or history of cancer in the past 2 years (except for non-melanoma skin cancer)
• Have had a heart or liver transplant, or anticipated need for transplant during the study treatment period including a scheduled kidney transplant. (Note: patients currently on a kidney transplant wait list are not excluded unless there is an identified donor).
• Alcohol abuse or substance use disorder within 1 year of Screening
• Subjects currently being treated with or having taken any one of the following medications (includes resins) in the 7 days prior to Screening: sodium or calcium polystyrene sulfonate, drospirenone
• Use of certain medications that can affect blood potassium levels if doses have not been stable for at least 14 days prior to Screening or if doses are anticipated to change during the 14-day PD / Dose Finding Phase
• Use of investigational product within 30 days of screening or within 5 half-lives, whichever is longer
• Known hypersensitivity to patiromer or its components
• In the opinion of the Investigator, any medical condition, uncontrolled systemic disease, or serious intercurrent illness that would significantly decrease study compliance or jeopardize the safety of the subject or potentially affect the quality of the data

• Subjects must meet ALL the following criteria to be eligible for the study. 1. Be adequately informed about the study and fully consent to participation as demonstrated by signing the written informed consent form before any screening procedure. 2. Men or Women , age 18 years or older Have relapsed or refractory B-cell NHL that, in the investigator's opinion, could benefit from MT-3724+LEN therapy. 3. At least one histology documented relapse of NHL by: 1. Bone marrow biopsy (FNA is not acceptable) 2. Excisional lymph node biopsy or 3. Core biopsy of any involved organ (FNA not acceptable) 4. CD20-positive histology must have been confirmed at any time during NHL disease course and documented in the medical history. 5. If no histology is available after any relapse the investigator can consult the medical monitor to discuss if the patient can be included 4. All subtypes of B-cell NHL may be considered for Part 1 (MT-3724 dose escalation). Only histologically documented DLBCL (including mixed histology) may be considered for Part 2 (expansion cohort) 5. Have received all available approved therapies for NHL. Those subjects who are ineligible for approved therapies in the opinion of the investigator, or have refused such therapies, will be eligible. 6. Have measurable disease by Lugano Classification for NHL (see Appendix 4): 1. >1.5 cm longest diameter (LDi) for lymph nodes 2. >1.0 cm LDi for extra nodal disease. 7. Eastern Cooperative Oncology Group (ECOG) performance score of ≤2 8. Have adequate bone marrow function, as determined by all the following: 1. Absolute neutrophil count (ANC) ≥1,000/mm³ 2. Platelet count ≥50,000 mm³ 9. Have adequate kidney function, assessed by the estimated glomerular filtration rate (eGFR) ≥60 mL/min calculated by the CPK-EPI equation. a. At the investigator's discretion, the eGFR result <60 mL/min may be verified by measurement of creatinine clearance (CLcr) based on the 24-hour urine collection. Subjects with CLcr ≥60 mL/min will be eligible irrespective of the eGFR result. 10. Have adequate hepatic function, as determined by: 1. Total bilirubin ≤1.5 x ULN, or ≤3 x ULN for subjects with Gilbert's Syndrome) and 2. AST ≤3 x ULN and 3. ALT ≤3 x ULN 11. Have adequate coagulation, as determined by: 1. INR or PT ≤1.5 x ULN 2. PTT ≤1.5 x ULN 12. Have adequate serum albumin, as determined by: a. Albumin ≥ 3.0 g/dL 13. Women of reproductive potential must have a negative pregnancy test on 2 occasions during the screening period (within 10-14 days and within 24 hours before the start of treatment). Women not of reproductive potential are female subjects who are postmenopausal or permanently sterilized (e.g., hysterectomy, bilateral salpingectomy). 14. Males must agree to always use a latex or synthetic condom during any sexual contact with females of reproductive potential while taking LEN and for up to 4 weeks after discontinuing LEN, even if they have undergone a successful vasectomy. Male patients taking LEN must not donate sperm. 15. Subjects of reproductive potential and their partners must agree to either to abstain continuously from heterosexual intercourse or to use 2 methods of reliable birth control simultaneously to begin 4 weeks prior to initiating treatment with LEN until 28 days after the last dose of MT-3724 or LEN. The investigator or a designated associate should advise the subject how to achieve adequate contraception. The following birth control methods may be considered: one highly effective form of contraception
•tubal ligation, IUD, hormonal (birth control pills, injections, hormonal patches, vaginal rings, or implants), or partner's vasectomy, and one additional effective contraceptive method
•male latex or synthetic condom, diaphragm, or cervical cap.
• Subjects who meet any of the following criteria must be excluded from the study. Medical and surgical history 1. History or current evidence of neoplastic disease that is histologically distinct from NHL, except cervical carcinoma in situ, superficial noninvasive bladder tumors, curatively treated Stage I-II non-melanoma skin cancer or any previous cancer curatively treated >2 years before the start of treatment. 2. Current evidence of new or growing brain or spinal metastases during screening. Subjects with known brain or spinal metastases may be eligible if they 1. Had radiotherapy or another appropriate therapy for the brain or spinal metastases 2. Have no neurological symptoms (excluding Grade ≤2 neuropathy) 3. Have stable brain or spinal disease on the CT or MRI scan within 1 month of enrollment 4. Do not require chronic steroid therapy 3. History of allogeneic hematopoietic stem cell transplant within 180 days before the start of treatment. 4. Current evidence of acute or chronic Graft versus Host Disease. 5. Current evidence of CTCAE Grade >1 toxicity (except for hair loss, and those toxicities listed in other eligibility criteria) before the start of treatment. 6. Current evidence of incomplete recovery from surgery before the start of treatment, or planned surgery at any time during the study until the EoT Visit, except minor elective interventions deemed acceptable by the investigator. 7. History or current evidence of significant (CTCAE Grade ≥2) infection or wound within 4 weeks before the start of treatment. 8. History or current evidence of significant cardiovascular disease including, but not limited to the following conditions: 1. Unstable angina (symptoms of angina at rest) or new-onset angina within ≤3 months before the start of treatment. 2. Arterial thrombosis or pulmonary embolism within ≤3 months before the start of treatment. 3. Myocardial infarction or stroke within ≤3 months before the start of treatment. 4. Pericarditis (any CTCAE grade), pericardial effusion (CTCAE Grade ≥2), non malignant pleural effusion (CTCAE Grade ≥2) or malignant pleural effusion (CTCAE Grade ≥3). 5. Congestive heart failure (NYHA Class III or IV) at screening or LVEF <45%, assessed by Echo or MUGA scan within 1 month before starting study treatment. (Echo or MUGA scan performed within 6 months before screening and at least 28 days after the last cancer therapy is acceptable provided the subject has not received any potential cardiotoxic agents). 6. Cardiac arrhythmia requiring anti-arrhythmic therapy at screening. Subjects receiving digoxin, calcium channel blockers, or beta-adrenergic blockers are eligible at the investigator's discretion after consultation with Medical Monitor if the dose has been stable for ≥2 weeks before the start of treatment. Subjects with sinus arrhythmia and infrequent premature ventricular contractions are eligible at the investigator's discretion. 9. QTcF (Fridericia) >480 ms, determined as the average from three QTcF values on the triplicate ECG obtained at screening. 10. Current evidence of seropositive status for HIV, hepatitis B (positive for HBsAg or anti-HBsAg and anti-HBcAg antibodies) or hepatitis C (positive for anti-HCV antibody or HCV-RCV-RNA quantitation) as assessed by the applicable serology testing at screening. 1. Serology testing is not required if seronegativity is documented in the medical history and there are no clinical signs suggestive of HIV or hepatitis infection. 2. Subjects with positive HBV serology are eligible if quantitative PCR for plasma HBV-DNA is negative and the subject will be receiving prophylaxis for potential HBV reactivation. 3. Subjects with positive HCV serology are eligible if quantitative PCR for plasma HCV RNA is negative. 11. Women who are pregnant or breastfeeding. 12. History or current evidence of hypersensitivity to any of the study drugs, or of current hypersensitivity requiring systemic steroids at doses >20 mg/day prednisone equivalent. 13. History or current evidence of any other medical or psychiatric condition or addictive disorder, or laboratory abnormality that, in the opinion of the investigator, may increase the risks associated with study participation, or require treatments that may interfere with the conduct of the study or the interpretation of study results. Prior treatments 14. Received anti-CD20 monoclonal antibody (Mab) therapy within the following periods before the start of treatment 1. Rituximab (Rituxan®): 84 days; if a subject had received rituximab within 37 Weeks before the start of treatment, then a serum rituximab level must be negative (<500 ng/mL) at screening. 2. Obinutuzumab (Gazyva®): 184 days 3. Ofatumumab (Arzerra®): 88 days 15. Received therapy for NHL (except the anti-CD20 Mab therapies listed above) within 4 weeks before the start of treatment. 16. Any investigational drug treatment from 4 weeks or 5 half-lives of the agent before the start of treatment, whichever is longer, until the EoT Visit. 17. Received radiotherapy to tumor lesions that would be chosen as target lesions (measurable disease) within 4 weeks before the start of treatment, unless the lesion exhibited objective progression between the radiotherapy and the screening according to the Lugano Classification for NHL. a. Palliative radiotherapy to non-target lesions is allowed at the investigator's discretion. 18. Received any vaccines within 28 days of the start of treatment, or likely to require vaccines at any time from the start of treatment until 28 days after the last dose of MT-3724. Injectable flu vaccine (inactivated or recombinant) is permitted at the investigator's discretion. 19. Received systemic immune modulators within 2 weeks before the start of treatment 1. Systemic immune modulators include but are not limited to systemic corticosteroids at doses >20 mg/day of prednisone equivalent, cyclosporine and tacrolimus. 2. The use of non-steroidal anti-inflammatory drugs (NSAIDs) is permitted

• MDS classified as follows:
• RAEB-1 per World Health Organization (WHO) MDS criteria (5% to <10% BM blasts)
• RAEB-2 per WHO MDS criteria (10% to <20% BM blasts)
• RAEB-t per French-American-British (FAB) classification (20% to 30% BM blasts)
• At least one cytopenia (ANC < 1800/µL or platelet count < 100,000/µL or hemoglobin [Hgb] < 10 g/dL)
• Progression (according to 2006 IWG criteria) at any time after initiation of AZA or DAC treatment or Failure to achieve complete or partial response or hematological improvement (HI) (according to 2006 IWG) after at least six 4-week cycles of AZA or either four 4-week or four 6-week cycles of DAC administered or Relapse after initial complete or partial response or HI (according to 2006 IWG criteria)
• Duration of prior HMA therapy ≤ 9 months and/or total ≤ 9 cycles of prior HMA therapy in ≤ 12 months
• Last dose of AZA or DAC within 6 months before the planned date of randomization; however, must be off these treatments for ≥ 4 weeks before randomization
• Has failed to respond to, relapsed following, not eligible for, or opted not to participate in allogeneic stem cell transplantation
• Off all treatments for MDS (including AZA and DAC) for ≥ 4 weeks before randomization; growth factors (G-CSF, erythropoietin and thrombopoietin) and transfusions are allowed before and during the study as clinically indicated
• Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1 or 2
• Willing to adhere to protocol prohibitions and restrictions
• Patient must sign informed consent form to indicate patient's understanding study's purpose and procedures and willingness to participate. Should patient be incapable of giving consent, the patient's legally authorized representative (as defined by local regulation) must give consent. However, should patient, in any manner, choose not to participate this takes precedence and will be respected.
• Patients with 5q- syndrome should have failed to respond to or progressed on treatment with lenalidomide, where available and indicated
• Previous participation in a clinical study of IV or oral rigosertib; patients who failed screening for other rigosertib studies may be screened for participation
• Eligible to receive induction chemotherapy, such as 7-10 days of cytosine arabinoside plus 2-3 days of an anthracycline, or high-dose cytarabine
• Suitable candidate to receive allogeneic stem cell transplantation; patient is eligible for study if a suitable candidate refuses to undergo an allogeneic stem cell transplant or a suitable donor cannot be found
• Any active malignancy within the past year, except basal cell or squamous cell skin cancer or carcinoma in situ that is unlikely to progress in two years
• Uncontrolled intercurrent illness including, but not limited to, symptomatic congestive heart failure or unstable angina pectoris
• Active infection not adequately responding to appropriate therapy
• Total bilirubin ≥1.5 mg/dL not related to hemolysis or Gilbert's disease
• Alanine transaminase (ALT)/aspartate transaminase (AST) ≥2.5 x upper limit of normal (ULN)
• Serum creatinine ≥2.0 mg/dL or eGFR (estimated Glomerular Filtration Rate) < 40 mL/min.
• Known active HIV, hepatitis B or hepatitis C, where active is defined as follows:
• HIV or hepatitis C
•presence of viral load
• Hepatitis B
•antigen positive
• Uncorrected hyponatremia (defined as serum sodium value of <130 mEq/L)
• Female patients of child-bearing potential and male patients with sexual partners of child-bearing potential who are unwilling to follow strict contraception requirements before entry and throughout the study, up to and including the 30-day non-treatment follow-up period. Examples of acceptable contraception methods include:
• estrogen-gestagen based contraceptives associated with inhibition of ovulation (oral, intravaginal, transdermal),
• gestagen-only based contraceptives associated with inhibition of ovulation (oral, injectable, implantable),
• intra-uterine devices (IUDs),
• intra-uterine hormone-releasing systems (IUSs),
• bilateral tubal occlusion
• vasectomized partner
• sexual abstinence in accordance with an individual's lifestyle
• Female patients of child-bearing potential (pre-menopausal and not surgically sterilized) who are breast-feeding or have a positive blood beta-human chorionic gonadotropin pregnancy test at Screening
• Major surgery without full recovery or within 3 weeks before planned randomization;
• Uncontrolled hypertension
• New onset seizures (within 3 months before planned randomization) or poorly controlled seizures
• Any other concurrent investigational agent or chemotherapy, radiotherapy, immunotherapy, or corticosteroids (prednisone up to 20 mg/day or its equivalent is permitted for chronic conditions)
• Treatment with cytarabine at any dose, lenalidomide, or any other therapy targeted to the treatment of MDS (other than growth factors and other supportive care measures) within 4 weeks of planned randomization
• Investigational therapy within 4 weeks of planned randomization
• Psychiatric illness or social situation that would limit the patient's ability to tolerate and/or comply with study requirements.
• Patient previously diagnosed with AML (defined as a bone marrow or peripheral blood blast percentage of >30%).

INCLUSION CRITERIA -Patients must be greater than or equal to 12 months and ≤ 21 years of age at the time of study enrollment. Patients must have one of the following: Leukemia
• Patients must have relapsed or refractory acute lymphoblastic leukemia (ALL) with greater than or equal to 25% blasts in the bone marrow (M3). OR
• Patients may have an M2 marrow (greater than or equal to 5% to < 25% blasts) with an extramedullary site of relapse; including CNS 2 and CNS 3.
• Refractory disease defined as no more than 1 prior failed salvage attempt following the current relapse, or no more than 2 additional treatment cycles after initial induction failure in newly diagnosed patients. Lymphoma
• Patient must have relapsed or refractory lymphoblastic lymphoma or peripheral T-cell lymphoma.
• Patient must have histologic verification of disease at original diagnosis.
• Patient must have evaluable or measurable disease documented by clinical or radiographic criteria or bone marrow disease present at study entry.
• Patients may have CNS 2 or 3 disease, if other sites of involvement. Karnofsky greater than or equal to 50% for patients > 16 years of age and Lansky greater than or equal to 50 for patients ≤ 16 years of age. Patients must have fully recovered from the acute toxic effects of all prior anti-cancer chemotherapy. Patients must have had 2 or more prior therapeutic attempts defined as:
• Relapse after going into remission from re-induction for the first or subsequent relapse (ie: 2nd , 3rd, 4th…relapse), or
• Patients with lymphoma may have refractory disease after first or greater relapse and a single re-induction attempt. Patients with leukemia or lymphoma who relapse while receiving maintenance chemotherapy will not be required to have a waiting period before enrollment onto this study. At least 14 days must have elapsed after the completion of cytotoxic therapy, with the exception of hydroxyurea. Hematopoietic growth factors: At least 14 days after the last dose of a long-acting growth factor (e.g. Neulasta) or 7 days for short-acting growth factor. Biologic (anti-neoplastic agent): At least 7 days after the last dose of a biologic agent. For agents that have known adverse events occurring beyond 7 days after administration, this period must be extended beyond the time during which adverse events are known to occur. The duration of this interval must be discussed with the study chair Immunotherapy: At least 42 days after the completion of any type of immunotherapy, e.g. tumor vaccines. or chimeric antigen receptor T cell (CART) therapy. Monoclonal antibodies: At least 3 half-lives of the antibody must have elapsed after the last dose of a monoclonal antibody. (ie: Rituximab = 66 days, Epratuzumab = 69 days). Patients must have been off blinatumomab infusion for at least 7 days and all drug-related toxicity must have resolved to grade 2 or lower as outlined in the inclusion and exclusion criteria XRT: At least 14 days after local palliative XRT (small port); At least 84 days must have elapsed if prior TBI, craniospinal XRT or if greater than or equal to 50% radiation of pelvis; At least 42 days must have elapsed if other substantial marrow radiation. Stem Cell Infusion: No evidence of active graft vs. host disease and at least 84 days must have elapsed after transplant or stem cell infusion. Study specific limitations on prior therapy: Patient may not have received therapy with an mTOR inhibitor. Adequate Bone Marrow Function Defined as: Blood counts are not required to be normal prior to enrollment on trial. However, platelet count must be greater than or equal to 20,000/mm3 to initiate therapy (may receive platelet transfusions). Patients should not be known to be refractory to red blood cell or platelet transfusions. Adequate Renal Function Defined as:
• Creatinine clearance or radioisotope GFR greater than or equal to 70ml/min/1.73 m2 or
• Normal serum creatinine based on age and gender. Adequate Liver Function Defined as:
• Total bilirubin (sum of conjugated + unconjugated) must be less than or equal to 1.5 x normal per institutional normal values for age.
• SGPT (ALT) and SGOT (AST) must be less than 3 x institutional upper limit of normal (Grade 1 or less per CTCAE 4). --GGT must be less than 2.5 x institutional upper limit of normal (Grade 1 or less per CTCAE 4).
• Serum albumin greater than or equal to 2 g/dL.
• The hepatic requirements may be waived for patients with elevations clearly due to leukemic infiltration after consultation with the Study Chair or Vice Chair.
• Fasting or non-fasting serum triglyceride level ≤ 300 mg/dL and serum cholesterol level ≤ 300 mg/dL. Adequate Cardiac Function Defined As:
• Shortening fraction of ≥ 27% by echocardiogram, or
• Ejection fraction of ≥ 50% by gated radionuclide study. Adequate Pulmonary Function Defined as:
• Pulse oximetry > 94% on room air (> 90% if at high altitude)
• No evidence of dyspnea at rest and no exercise intolerance.
• Baseline chest x-ray with no evidence of active infectious disease or pneumonitis. Reproductive Function
• Female patients of childbearing potential must have a negative urine or serum pregnancy test confirmed prior to enrollment.
• Female patients with infants must agree not to breastfeed their infants while on this study.
• Male and female patients of child-bearing potential must agree to use an effective method of contraception approved by the investigator during the study.
• Random or fasting glucose within the upper limits of normal for age. If the initial blood glucose is non-fasting and above normal limits a fasting glucose can be obtained and must be within the upper limits of normal for age. EXCLUSION CRITERIA
• Corticosteroids: Patients receiving corticosteroids who have not been on a stable or decreasing dose of corticosteroid for at least 7 days prior to enrollment are not eligible.
• Investigational Drugs: Patients who are currently receiving another investigational drug are not eligible. The definition of "investigational" for use in this protocol means any drug that is not licensed by the FDA, Health Canada or the Therapeutic Goods Administration to be sold in the countries they govern. (United States, Canada and Australia)
• Anti-cancer Agents: Patients who are currently receiving or may receive while on therapy, other anti-cancer agents, radiation therapy or immunotherapy are not eligible [except leukemia patients receiving hydroxyurea, which may be continued until 24 hours prior to start of protocol therapy]. Intrathecal chemotherapy (at the discretion of the primary oncologist) may be given up to one week prior to the initiation of study therapy.
• Anti-GVHD or agents to prevent organ rejection post-transplant: Patients who are receiving cyclosporine, tacrolimus or other agents to prevent either graft-versus-host disease post bone marrow transplant or organ rejection post transplant are not eligible for this trial. At least 3 half-lives must have elapsed after the last dose of GVHD meds.
• Anticoagulants: Patients who are currently receiving therapeutic anticoagulants (including aspirin, low molecular weight heparin, and others) are not eligible. At least 3 half-lives must have elapsed after the last dose of anticoagulants.
• Angiotensin-converting enzyme (ACE) inhibitors: Patients who are currently receiving ACE inhibitors are not eligible due to the development of angioneurotic edema-type reactions in some subjects who received concurrent treatment with temsirolimus + ACE inhibitors. At least 3 half-lives must have elapsed after the last dose of ACE inhibitors.
• Enzyme inducing Anti-convulsants: Patients who are currently receiving enzyme inducing anticonvulsants (ie phenytoin, phenobarbitol, or carbamazepine) are not eligible. Stabilizing on a non-hepatic inducing metabolizing anti-convulsant (ie: gabapentin or levetiracetam) prior to study entry is acceptable. At least 3 half-lives must have elapsed after the last dose of enzyme inducing anti-coagulants.
• Patients receiving treatment with azoles such as fluconazole or voriconazole which are potent inhibitors of temsirolimus metabolism. At least 3 half-lives must have elapsed after the last dose of azoles. Infection Criteria Patients are excluded if they have:
• Positive blood culture within 48 hours of study enrollment;
• Fever above 38.2 within 48 hours of study enrollment with clinical signs of infection. Fever that is determined to be due to tumor burden is allowed if patients have documented negative blood cultures for at least 48 hours prior to enrollment and no concurrent signs or symptoms of active infection or hemodynamic instability.
• A positive fungal culture within 30 days.
• Active fungal, viral, bacterial, or protozoal infection requiring IV treatment. Chronic prophylaxis therapy to prevent infections is allowed. Patients with Down syndrome and Fanconi Anemia are excluded. Patients will be excluded if they have significant concurrent disease, illness, psychiatric disorder or social issue that would compromise patient safety or compliance with protocol treatment or required observations, interfere with consent, study participation, follow up, or interpretation of study results. Patients with known optic nerve and/or retinal involvement (because it may not be possible to safely delay irradiation) are not eligible. Patients presenting with visual disturbances by history or physical exam should have an ophthalmological exam and, if indicated, an MRI to determine optic nerve or retinal involvement.

• Participants with 1 to less than (<) 18 years of age (Part 1 only), or 1 to 30 years of age, inclusive, if initial diagnosis of mature B-cell non-Hodgkin lymphoma (NHL) occurred at <18 years of age (Part 2 only)
• Participants must be in first recurrence and have received only one prior line of therapy or have disease that is primarily refractory to conventional therapy
• Participants must have at least 1 of the following: 1 site of measurable disease greater than (>) 1 centimeter (cm) in the longest diameter and >1 cm in the shortest diameter by radiological imaging; bone marrow involvement; cerebrospinal fluid with blasts present
• Participants with lansky-Karnofsky score of greater than or equal to (>=) 50
• Adolescent women/young women of childbearing potential must have a negative highly sensitive serum or urine beta-human chorionic gonadotropin (beta-hCG) pregnancy test at Screening before enrollment/randomization. Adolescent/young women who are pregnant or breastfeeding are ineligible for this study
• Participants with ongoing anticoagulation treatment with warfarin or equivalent vitamin K antagonists (example phenprocoumon), or ongoing treatment with agents known to be strong CYP3A4/5 inhibitors, or has taken any disallowed therapies as noted in Section 8.2, Prohibited Medications, before the planned first dose of study drug
• Participants with inherited or acquired bleeding disorders
• Participants with clinically significant arrhythmias, complex congenital heart disease, or left ventricular ejection fraction (LVEF) <50 percent (%) or shortening fraction (SF) <=28%
• Participants with known history of human immunodeficiency virus (HIV) or active Hepatitis B or C virus
• Participants with any condition that could interfere with the absorption or metabolism of ibrutinib including malabsorption syndrome, disease significantly affecting gastrointestinal function, or resection of the stomach or small bowel
• Participants with known allergies, hypersensitivity, or intolerance to ibrutinib or its excipients (refer to Investigator's Brochure)
• A diagnosis of post-transplant lymphoproliferative disease (PTLD)
• Participants who are within 6 months of an allogeneic bone marrow transplant
• Participants who have had prior exposure to ibrutinib

• Must have relapsed or refractory acute lymphoblastic leukemia (ALL) or relapsed or refractory lymphoblastic lymphoma (LL). Refractory is defined as persistent disease after at least 2 courses of chemotherapy.
• Participants with ALL with Philadelphia chromosome or with an ABL class targetable fusion are eligible.
• Participants with LL must have radiographic evidence of disease
• Participants <= 18 years of age who do not have a standard of care treatment option available.
• Must weigh greater than or equal to 20 kg.
• Must be able to swallow pills.
• Must have adequate hepatic and kidney function.
• Must have adequate performance status:
• Participants less than or equal to 16 years of age: Lansky greater than or equal to 50
• Participants greater than 16 years of age: Karnofsky greater than or equal to 50 or Eastern Cooperative Oncology Group (ECOG) less than 3.
• Participant has central nervous system (CNS) disease with cranial involvement that requires radiation.
• Participants who are less than 100 days post-transplant, or greater than 100 days post-transplant with active graft versus host disease (GVHD), or are still continuing post-transplant immunosuppressant therapy within 7 days prior to the first dose of study drug.
• Participants who have received any of the following prior to the first dose of study drug:
• Inotuzumab within 30 days (if participant received inotuzumab > 30 days prior to Day 1, must have ALT, AST and bilirubin < ULN).
• A biologic agent (i.e., monoclonal antibodies) for anti-neoplastic intent within 30 days
• CAR-T infusion or other cellular therapy within 30 days
• Any anti-cancer therapy including blinatumomab, chemotherapy, radiation therapy targeted small molecule agents or investigational agents within 14 days, or 5 half-lives, whichever is shorter
• Exception: Philadelphia Chromosome (Ph)+ ALL subjects on TKIs at Screening may enroll and remain on Tyrosine Kinase Inhibitor (TKI) therapy to control disease. Participants on venetoclax at screening may enroll and remain on venetoclax.
• Steroid therapy for anti-neoplastic intent within 5 days
• Hydroxyurea that is ongoing (hydroxyurea is permitted up to the first dose)
• A strong or moderate CYP3A inhibitor or inducer within 7 days
• Aspirin within 7 days, or 5 half-lives, whichever is longer
• An excluded antiplatelet/anticoagulant drug or a herbal supplement that affects platelet function within 7 days, or 5 half-lives, whichever is longer
• Participants with malabsorption syndrome or any other condition that precludes enteral administration.

• Pathologically proven acute myeloid leukemia (AML) (except acute promyelocytic leukemia [APL] with the t(15;17) translocation) or intermediate, high-risk, or very high risk Myelodysplastic Syndrome (MDS) as defined by the World Health Organization (WHO) criteria or Revised International Prognostic Scoring System (IPSS-R) which is relapsed or refractory (R/R) to standard therapy and/or for which standard therapy is contraindicated or which has not adequately responded to standard therapy.
• Patients must have documented IDH1-R132 gene-mutated disease as evaluated by the site
• Good performance status
• Good kidney and liver function
• Patients with symptomatic central nervous system (CNS) metastases or other tumor location (such as spinal cord compression, other compressive mass, uncontrolled painful lesion, bone fracture, etc.) necessitating an urgent therapeutic intervention, palliative care, surgery or radiation therapy
• Congestive heart failure (New York Heart Association Class III or IV) or unstable angina pectoris. Previous history of myocardial infarction within 1 year prior to study entry, uncontrolled hypertension or uncontrolled arrhythmias
• Pulmonary disease (e.g. COPD, asthma, etc) that is not controlled (moderate to severe symptoms) with current medication
• Active, uncontrolled bacterial, viral, or fungal infections, requiring systemic therapy

• Applicable disease criteria
• Patients must have one or two partially HLA-matched CBUs
• Back-up stem cell source
• Adequate Karnofsky/Lansky Performance score
• Sufficient physiological reserves
• Signed written informed consent
• HLA-matched donor able to donate
• Prior allogeneic HSCT
• Other active malignancy
• Active or uncontrolled infection
• Active/symptoms of central nervous system (CNS) disease
• Pregnancy or lactation

1. CD19 expressing B-cell Acute Lymphoblastic Leukemia 2. De novo NCI HR B-ALL who received first-line treatment and are MRD ≥ 0.01% at EOC. EOC bone marrow MRD will be collected prior to screening and will be assessed by multi-parameter flow cytometry using central laboratory analysis. 3. Age 1 to 25 years at the time of screening 4. Lansky (age < 16 years) or Karnofsky (age ≥ 16 years) performance status ≥ 60% 5. Adequate organ function during the screening period: A. Renal function based on age/gender B. ALT ≤ 5 times ULN for age C. AST ≤ 5 times ULN for age D. Total bilirubin < 2 mg/dL (for Gilbert's Syndrome subjects total bilirubin < 4 mg/dL) E. Adequate pulmonary function defined as:
• no or mild dyspnea (≤ Grade 1)
• oxygen saturation of > 90% on room air F. Adequate cardiac function defined as LVSF ≥ 28% confirmed by echocardiogram or LVEF ≥ 45% confirmed by echocardiogram or MUGA within 6 weeks of screening 6. Prior induction and consolidation chemotherapy allowed: 1st line subjects: ≤ 3 blocks of standard chemotherapy for first-line B-ALL, defined as 4-drug induction, augmented Berlin-Frankfurt-Münster (BFM) consolidation, and interim maintenance with high-dose methotrexate. 1. M3 marrow at the completion of 1st line induction therapy 2. M2 or M3 marrow or persistent extramedullary disease at the completion of first-line consolidation therapy. Patients with previous CNS disease are eligible if there is no active CNS involvement of leukemia at the time of enrollment. 3. Philadelphia chromosome positive ALL 4. Hypodiploid: less than 44 chromosomes and/or DNA index < 0.81, or other clear evidence of a hypodiploid clone 5. Prior tyrosine kinase inhibitor therapy 6. Subjects with concomitant genetic syndromes associated with bone marrow failure states: such as subjects with Fanconi anemia, Kostmann syndrome, Shwachman syndrome or any other known bone marrow failure syndrome. Subjects with Down syndrome will not be excluded. 7. Subjects with Burkitt's lymphoma/leukemia (i.e. subjects with mature B-ALL, leukemia with B-cell [sIg positive and kappa or lambda restricted positivity] ALL, with FAB L3 morphology and /or a MYC translocation) 8. Has had treatment with any prior anti-CD19 therapy 9. Treatment with any prior gene or engineered T cell therapy Other protocol-defined inclusion/exclusion may apply.

• Age Patients must be ≤21 years of age at the time of enrollment. 1. Phase 1
•Initial enrollment will be restricted to patients < 18 years of age until 9 such patients are enrolled 2. Phase 2
•Initial enrollment will be restricted to patients < 18 years of age until 6 such patients are enrolled
• Diagnosis Patients must have a diagnosis of relapsed/refractory ALL or LLy with or without extramedullary disease (including CNS2 and CNS3). Patient with mixed phenotype ALL or mature B (Burkitt-like) leukemia are not eligible. 1. Patients with ALL must have ≥ 5% blasts by morphology. 2. Patients with LLy must have measurable disease documented by clinical, radiologic or histologic criteria
• Performance Level Karnofsky ≥ 50% for patients > 16 years of age and Lansky ≥ 50% for patients ≤ 16 years of age.
• Prior Therapy A. Prior therapeutic attempts
• Phase 1
•Any patients with relapsed/refractory ALL or LLy
• Phase 2 1. B-cell ALL/LLy: all patients must have failed two or more therapeutic attempts. 2. T-cell ALL/LLy: all patients must have failed one or more therapeutic attempts. B. Recent prior chemotherapy Patients must have fully recovered from the acute toxic effects of all prior chemotherapy, immunotherapy, or radiotherapy prior to entering this study.
• Cytoreduction with hydroxyurea Hydroxyurea can be initiated and continued for up to 24 hours prior to the start of protocol therapy.
• Patients who relapsed while they are receiving cytotoxic therapy At least 14 days must have elapsed since the completion of the last dose of chemotherapy,except Intrathecal chemotherapy, and/or maintenance therapy such as vincristine, mercaptopurine, methotrexate or glucocorticoids. There is no waiting period for those relapsing on maintenance therapy. C. Hematopoietic stem cell transplant: Patients who have experienced their relapse after a HSCT are eligible, provided they have no evidence of acute or chronic Graft-versus-Host Disease (GVHD), are not receiving GVHD prophylaxis or treatment, and are at least 90 days post-transplant at the time of enrollment. D. Hematopoietic growth factors: It must have been at least 7 days since the completion of therapy with G-CSF or other growth factors at the time of enrollment. It must have been at least 14 days since the completion of therapy with pegfilgrastim (Neulasta®). E. Biologic (anti-neoplastic agent): At least 7 days since the last dose of a biologic agent. For agents that have known adverse events occurring beyond 7 days after administration, this period must be extended beyond the time during which adverse events are known to occur. The duration of this interval must be discussed with the study chair 1. Monoclonal antibodies: At least 3 half-lives of the antibody must have elapsed after the last dose of monoclonal antibody. (i.e., blinatumomab = 6 hours,44 inotuzumab = 37 days, rituximab = 66 days) 2. Immunotherapy: At least 30 days after the completion of any type of immunotherapy, e.g., tumor vaccines, CAR T cells. F. XRT: Craniospinal XRT is prohibited during protocol therapy. No washout period is necessary for radiation given to any extramedullary site other than CNS; ≥90 days must have elapsed if prior total body irradiation (TBI) or craniospinal XRT. G. Anthracyclines: Patients must have had a lifetime exposure of <400 mg/m2 of doxorubicin equivalents of anthracyclines. H. Proteasome inhibitors: Patients with a prior exposure to proteasome inhibitors (e.g., bortezomib, carfilzomib) are eligible as long as the patient demonstrated at least a partial response to a proteasome inhibitor with chemotherapy combination. -Renal and hepatic function Patients must have adequate renal and hepatic functions as indicated by the following laboratory values: A. Adequate renal function defined as: Patient must have a calculated creatinine clearance or radioisotope GFR 70ml/min/1.73m2 OR a normal serum creatinine based on age/gender B. Adequate Liver Function Defined as: Direct bilirubin ≤ 1.5 x upper limit of normal (ULN) for age or normal (except in the presence of Gilbert's syndrome), AND alanine transaminase (ALT) ≤ 5 x ULN for age. The hepatic requirements are waived for patients with known or suspected liver involvement by leukemia or lymphoma. This must be reviewed by and approved by the study chair or vice chair.
• Adequate Cardiac Function Defined as: Shortening fraction of more than or equal to 27% by echocardiogram, OR ejection fraction of equal to or more than 50% by radionuclide angiogram (MUGA).
• Reproductive Function A. Female patients of childbearing potential must have a negative urine or serum pregnancy test confirmed within 2 weeks prior to enrollment. B. Female patients with infants must agree not to breastfeed their infants while on this study. C. Male and female patients of child-bearing potential must agree to use an effective method of contraception approved by the investigator during the study and for a minimum of 6 months after study treatment.
• Informed Consent Patients and/or their parents or legal guardians must be capable of understanding the investigational nature, potential risks and benefits of the study. All patients and/or their parents or legal guardians must sign a written informed consent. Age appropriate assent will be obtained per institutional guidelines. To allow non-English speaking patients to participate in this study, bilingual health services will be provided in the appropriate language when feasible.
• All institutional, FDA, and OHRP requirements for human studies must be met. Patients will be excluded if they have isolated CNS or testicular disease. Patients will be excluded if they have ≥grade 2 peripheral sensory or motor neuropathy (defined by the Modified "Balis" Pediatric Scale of Pediatric Neuropathies) at the time of enrollment (see section 4.7.1.1). Patients will be excluded if they have a known allergy or intolerance to any of the drugs used in the study
•except for PEG-asparaginase for which erwinia asparaginase may be substituted Patients will be excluded if they have a systemic fungal, bacterial, viral or other infection that is exhibiting ongoing signs/symptoms related to the infection without improvement despite appropriate antibiotics or other treatment. The patient needs to be off pressors and have negative blood cultures for 48 hours. Patients will be excluded if there is a plan to administer non-protocol chemotherapy, radiation therapy, or immunotherapy during the study period. Patients will be excluded if they have significant concurrent disease, illness, psychiatric disorder or social issue that would compromise patient safety or compliance with the protocol treatment or procedures, interfere with consent, study participation, follow up, or interpretation of study results. Patients with DNA fragility syndromes (such as Fanconi anemia, Bloom syndrome) are excluded. Patients will be excluded if they have had a lifetime exposure of ≥400 mg/m2 doxorubicin equivolents of anthracyclines (anthracycline equivalence to doxorubicin conversion see appendix iv) . Concomitant medications Investigational drugs: Patients currently receiving another investigational drug are not eligible. Anti-GVHD agents post transplant: patients who are receiving cyclosporine, tacrolimus or other agents to prevent graft-versus-host disease post hematopoetic stem cell transplant are not eligible. CYP3A4 agents: patients who are currently receiving drugs that are strong inducers of CYP3A4 are not eligible. Strong inducers of CYP3A4 should be avoided from 14 days prior to enrollment to the end of the study. See appendix ii for a list of agents which fall into this category. Patients with Ph+ALL and Ph-like ALL who are currently receiving TKI therapy Infants or Patients with Down Syndrome will be excluded in phase 2 of the study

• B-ALL and MPAL patients must be enrolled on APEC14B1 and consented to eligibility studies (Part A) prior to treatment and enrollment on AALL1732. Note that central confirmation of MPAL diagnosis must occur within 7 business days after enrollment for MPAL patients. If not performed within this time frame, patients will be taken off protocol.
• APEC14B1 is not a requirement for B-LLy patients but for institutional compliance every patient should be offered participation in APEC14B1. B LLy patients may directly enroll on AALL1732 and MUST submit eligibility studies as outlined.
• White blood cell count (WBC) criteria for patients with B-ALL (within 7 days prior to the start of protocol-directed systemic therapy):
• Age 1-9.99 years: WBC >= 50,000/uL
• Age 10-24.99 years: Any WBC
• Age 1-9.99 years: WBC < 50,000/uL with:
• Testicular leukemia
• CNS leukemia (CNS3)
• Steroid pretreatment.
• White blood cell count (WBC) criteria for patients with MPAL (within 7 days prior to the start of protocol-directed systemic therapy):
• Age 1-24.99 years: any WBC.
• Patient has newly diagnosed B-ALL or MPAL (by World Health Organization [WHO] 2016 criteria) with > 25% blasts on a bone marrow (BM) aspirate;
• OR If a BM aspirate is not obtained or is not diagnostic of acute leukemia, the diagnosis can be established by a pathologic diagnosis of acute leukemia on a BM biopsy;
• OR A complete blood count (CBC) documenting the presence of at least 1,000/uL circulating leukemic cells if a bone marrow aspirate or biopsy cannot be performed.
• Patient has newly diagnosed B-LLy Murphy stages III or IV.
• Patient has newly diagnosed B-LLy Murphy stages I or II with steroid pretreatment.
• Note: For B-LLy patients with tissue available for flow cytometry, the criterion for diagnosis should be analogous to B-ALL. For tissue processed by other means (i.e., paraffin blocks), the methodology and criteria for immunophenotypic analysis to establish the diagnosis of B-LLy defined by the submitting institution will be accepted.
• All patients and/or their parents or legal guardians must sign a written informed consent.
• All institutional, Food and Drug Administration (FDA), and NCI requirements for human studies must be met.
• Patients with Down syndrome are not eligible (patients with Down syndrome and B-ALL are eligible for AALL1731, regardless of NCI risk group).
• Patients with known Charcot-Marie-Tooth disease.
• With the exception of steroid pretreatment or the administration of intrathecal cytarabine, patients must not have received any prior cytotoxic chemotherapy for the current diagnosis of B-ALL, MPAL, or B-LLy or for any cancer diagnosed prior to initiation of protocol therapy on AALL1732.
• Patients with B-ALL or MPAL who do not have sufficient diagnostic bone marrow submitted for APEC14B1 testing and who do not have a peripheral blood sample submitted containing > 1,000/uL circulating leukemia cells.
• Patients with acute undifferentiated leukemia (AUL) are not eligible.
• For Murphy stage III/IV B-LLy patients, or stage I/II patients with steroid pretreatment, the following additional exclusion criteria apply:
• T-lymphoblastic lymphoma.
• Morphologically unclassifiable lymphoma.
• Absence of both B-cell and T-cell phenotype markers in a case submitted as lymphoblastic lymphoma.
• 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 women who plan to breastfeed their infants while on study and for 2 months after the last dose of inotuzumab ozogamicin.
• Sexually active patients of reproductive potential who have not agreed to use an effective contraceptive method for the duration of study participation. For those patients randomized to inotuzumab ozogamicin, there is a minimum of 8 months after the last dose of inotuzumab ozogamicin for females and 5 months after the last dose of inotuzumab ozogamicin for males.

• Group 1: Must have newly diagnosed, pathologically confirmed cHL at Stages IA, IB and IIA without bulky disease. Group 2: Must have newly diagnosed, pathologically confirmed cHL at Stages IIEB, IIIEA,IIIEB, IIIB, IVA and IVB
• Has measurable disease per investigator assessment
• Male participants must agree to use approved contraception during the treatment period and for at least 120 days (or longer, if required by the drug label of chemotherapy received by the participant on study) after the last dose of study treatment and refrain from donating sperm during this period
• Female participants who are not pregnant or breastfeeding, and who are either not a woman of childbearing potential (WOCBP), or are a WOCBP who agrees to use approved contraception during the treatment period and for at least 120 days (or longer, if required by the drug label of chemotherapy received by the participant on study) after the last dose of study treatment
• Performance status: Lansky Play-Performance Scale ≥50 for children up to and including 16 years of age OR Karnofsky score ≥50 for participants >16 years of age
• Has adequate organ function
• Has undergone solid organ transplant at any time, or prior allogeneic hematopoietic stem cell transplantation within the last 5 years
• WOCBP who has a positive urine pregnancy test within 72 hours before the first dose of study treatment
• Baseline left ventricular ejection fraction value <50% or shortening fraction of <27%
• Has received prior therapy with an anti-Programmed Death (PD)-1, anti-Programmed Death-Ligand 1 (PD-L1), or anti-PD-L2 agent or with an agent directed to another co-inhibitory T-cell receptor or has previously participated in a Merck pembrolizumab (MK-3475) clinical study
• Has received any prior anti-cancer therapy, monoclonal antibody, chemotherapy, or an investigational agent or device before the first dose of study treatment, or has not recovered from AEs due to previously administered agents
• Has received a live vaccine within 30 days prior to the first dose of pembrolizumab
• 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 treatment
• Has a diagnosis of lymphocyte-predominant Hodgkin Lymphoma (HL)
• 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 pembrolizumab
• Has a known additional malignancy that is progressing or requires active treatment
• Has radiographically detectable central nervous system metastases and/or carcinomatous meningitis as assessed by local site investigator at the time of diagnosis
• Has severe hypersensitivity (≥Grade 3) to any study therapies including any excipients
• Has an active autoimmune disease that has required systemic treatment in past 2 years
• Has a history of (non-infectious) 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 or known active Hepatitis C virus infection
• Has a known history of active tuberculosis
• Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the study, interfere with the participant's participation for the full duration of the study, or is not in the best interest of the participant to participate, in the opinion of the treating investigator
• Has known psychiatric or substance abuse disorders that would interfere with cooperating with the requirements of the study
• Is pregnant or breastfeeding or expecting to conceive or father children within the projected duration of the trial, starting with the screening visit through 120 days (or longer, if required by the drug label of chemotherapy received by the participant on study) after the last dose of trial treatment

• Inclusion criteria
•Recipient Disease specific: Sickle Cell Disease
•Patients with sickle cell disease at high risk for disease related morbidity or mortality, defined by having irreversible end-organ damage (A, B, C,D, or E) or potentially reversible complication(s) not ameliorated by hydroxyurea (F): A. Stroke defined as a clinically significant neurologic event that is accompanied by an infarct on cerebral MRI OR an abnormal trans-cranial Doppler examination (≥200m/s); OR B. Sickle cell related renal insufficiency defined by a creatinine level ≥1.5 times the upper limit of normal and kidney biopsy consistent with sickle cell nephropathy OR nephrotic syndrome OR creatinine clearance < 50mL/min OR requiring peritoneal or hemodialysis. OR C. Pulmonary hypertension as defined by tricuspid regurgitant jet velocity (TRV) of ≥ 2.5m/s at least 3 weeks after a vaso-occlusive crisis; OR D. Recurrent tricorporal priapism defined as at least two episodes of an erection lasting ≥4 hours involving the corpora cavernosa and corpus spongiosa; OR E. Sickle hepatopathy defined as EITHER ferritin >1000mcg/L OR direct bilirubin >0.4 mg/dL at baseline; OR F. Any one of the below complications 1. Vaso-occlusive crises 2. Acute chest syndrome 3. Osteonecrosis of 2 or more joints 4. Red cell alloimmunization Thalassemia
•Patients with thalassemia who have grade 2 or 3 iron overload, determined by the presence of 2 or more of the following: • portal fibrosis by liver biopsy inadequate chelation history (defined as failure to maintain adequate compliance with chelation with desferroxamine initiated within 18 months of the first transfusion and administered subcutaneously for 8-10 hours at least 5 days each week) hepatomegaly of greater than 2 cm below the costochondral margin Non-disease specific: Ages ≥ 18 but ≤ 45 6/6 HLA matched family donor available Ability to comprehend and willing to sign an informed consent, assent obtained from minors Negative serum pregnancy test Inclusion criteria
•Donor 6/6 HLA identical family donor Weight > 20 kg (in so far that the weight difference between recipient and donor does not exceed a reasonable likelihood of being able to obtain an adequate cell dose from the donor within two aphereses) Fit to receive G-CSF and give peripheral blood stem cells (normal blood counts, normotensive, and no history of stroke) Ability to comprehend and willing to sign an informed consent Exclusion criteria
•Recipient Any of the following would exclude the subject from participating ECOG performance status of 3 or more or Lanksy performance status of <40 Diffusion capacity of carbon monoxide (DLCO) <50% predicted (corrected for hemoglobin and alveolar volume) Baseline oxygen saturation of <85% or PaO2 <70 Left ventricular ejection fraction: <40% estimated by ECHO Transaminases > 5x upper limit of normal for age Evidence of uncontrolled bacterial, viral, or fungal infections (currently taking medication and progression of clinical symptoms) within one month prior to starting the conditioning regimen Major anticipated illness or organ failure incompatible with survival from PBSC transplant Pregnant or lactating 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. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. 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) Major ABO mismatch Exclusion criteria
•Donor Any of the following would exclude the donor from participating Pregnant or lactating 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. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. 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) HIV positive Hemoglobin S > 50%, or beta thalassemia intermediate

• Between 6 months and <18 years of age (or between 3 years and <18 years of age for rrcHL participants) on day of signing informed consent/assent (the first 3 participants dosed in Part 1 are to be ≥ 6 years of age)
• Histologically- or cytologically-documented, locally-advanced, or metastatic solid malignancy or lymphoma that is incurable and has failed prior standard therapy, or for which no standard therapy exists, or for which no standard therapy is considered appropriate
• Any number of prior treatment regimens
• Tissue (or lymph node biopsy for rrcHL participants) available from an archival tissue sample or, if appropriate, a newly obtained core or excisional biopsy of a tumor lesion not previously irradiated
• Advanced melanoma or PD-L1-positive advanced, relapsed, or refractory solid tumor or lymphoma
• Measurable disease based on RECIST 1.1 (Or based on IWG [Cheson, 2007] [i.e., measurement must be >15 mm in longest diameter or >10 mm in short axis] for rrcHL participants)
• Participants with neuroblastoma with only metaiodobenzylguanidine (MIBG)-positive evaluable disease may be enrolled
• Lansky Play Scale ≥50 for participants from 6 months up to and including 16 years of age; or Karnofsky score ≥50 for participants >16 years of age
• Adequate organ function
• Female participants of childbearing potential should have a negative urine or serum pregnancy test within 72 hours prior to receiving the first dose of study medication
• Female participants of childbearing potential must be willing to use 2 methods of contraception or be surgically sterile, or abstain from heterosexual activity for the course of the study through 120 days after the last dose of study medication
• Male participants of reproductive potential must agree to use an adequate method of contraception starting with the first dose of study medication through 120 days after the last dose of study medication
• Currently participating and receiving study therapy in, or has participated in a study of an investigational agent and received study therapy or used an investigational device within 4 weeks of the date of allocation/randomization
• Diagnosis of immunodeficiency or receiving systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the date of allocation/randomization
• Prior systemic anti-cancer therapy including investigational agent within 2 weeks prior to study Day 1 or not recovered from adverse events due to a previously administered agent
• Prior radiotherapy within 2 weeks of start of study treatment
• Known additional malignancy that is progressing or requires active treatment with the exception of basal cell carcinoma of the skin, squamous cell carcinoma of the skin or carcinoma in situ (eg, breast carcinoma, cervical carcinoma in situ) with potentially curative therapy, or in situ cervical cancer
• Known active central nervous system (CNS) metastases and/or carcinomatous meningitis
• Tumor(s) involving the brain stem
• Severe hypersensitivity (≥ Grade 3) to pembrolizumab and/or any of its excipients
• Active autoimmune disease that has required systemic treatment in past 2 years; replacement therapy (such as thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency) is acceptable
• Has a history of (non-infectious) pneumonitis that required steroids or current pneumonitis.
• Active infection requiring systemic therapy
• Pregnant or breastfeeding, or expecting to conceive or father children within the projected duration of the trial through 120 days after the last dose of study medication
• Prior therapy with an anti-programmed cell death (PD)-1, anti-PD-ligand 1 (anti-PD-L1), anti-PD-L2 agent, or any agent directed to another stimulatory or inhibitory T-cell receptor (eg, cytotoxic lymphocyte associated protein-4 [CTLA-4], OX-40, CD137)
• Human immunodeficiency virus (HIV)
• Hepatitis B or C
• Known history of active tuberculosis (TB; Bacillus tuberculosis)
• Received a live vaccine within 30 days of planned start of study medication
• Has undergone solid organ transplant at any time, or prior allogeneic hematopoietic stem cell transplantation within the last 5 years. (Participants who have had an allogeneic hematopoietic transplant >5 years ago are eligible as long as there are no symptoms of Graft Versus Host Disease [GVHD].)
• History or current evidence of any condition, therapy, or laboratory abnormality, or known severe hypersensitivity to any component or analog of the trial treatment, that might confound the results of the trial, or interfere with the participant's participation for the full duration of the study
• Known psychiatric or substance abuse disorders that would interfere with the requirements of the study

1. Disease Status and Prior Therapy: 1. Histologically confirmed AML with >20% blasts 2. Phase 1b: Participants with AML who are refractory to or have relapsed after initial treatment for their disease, with no more than three prior lines of therapy. Participants who have received prior treatment with cytarabine or decitabine are not excluded. 3. Phase 2: i. Participants with AML who are refractory to, or have relapsed after, initial treatment for their disease, with no more than one prior line of therapy, and are judged not to be candidates for re-induction therapy that includes hematopoietic cell transplantation. Participants who have received prior cytarabine or decitabine are not excluded. OR ii. Participants with newly diagnosed, untreated AML ineligible for, or who have refused, standard intensive induction therapy 2. Age ≥18 years 3. ECOG performance status ≤2 4. Participants must be willing and able to review, understand, and provide written consent before starting any study-specific procedures or therapy. 5. All men and women must agree to practice effective contraception during the entire study period and after discontinuing study drug, unless documentation of infertility exists 1. Sexually active, fertile women must use two effective forms of contraception (abstinence, intrauterine device, oral contraceptive, or double barrier device) from the time of informed consent and until at least 6 months after discontinuing study drug 2. Sexually active men and their sexual partners must use effective contraceptive methods from the time of participant informed consent and until at least 3 months after discontinuing study drug 1. Treatment-related AML or acute promyelocytic leukemia (APL) 2. Active malignancies within 12 months with the exception of those with a negligible risk of metastasis or death 3. Clinical evidence of active central nervous system leukemia at the time of screening 4. Alanine aminotransferase and/or aspartate aminotransferase ≥2.5 x upper limit of normal (ULN) 5. Total bilirubin > 2.0 mg/dL (or > 3.0 mg/dL in participants with documented Gilbert syndrome) 6. Serum creatinine ≥2.0 mg/dL 7. New York Heart Association Class III or IV heart disease, active ischemia or any other uncontrolled cardiac condition, or hypertensive or metabolic condition 8. Myocardial infarction in the previous 12 weeks (from the start of treatment) 9. Resting left ventricular ejection fraction <50% at the time of screening 10. QT (Interval from the beginning of the QRS complex to the end of the T wave on an electrocardiogram) interval with Fridericia's correction [QTcF] >450 milliseconds. The QTcF should be calculated as the arithmetic mean of the QTcF on triplicate ECGs. In the case of potentially correctible causes of QT prolongation (e.g., medications, hypokalemia), the triplicate ECG may be repeated once during screening and that result may be used to determine eligibility. 11. Active and uncontrolled disease (other than AML) or infection as judged by the treating physician 12. Treatment with systemic therapy for the primary disease within 14 days (except for hydroxyurea or isolated doses of cytarabine or decitabine for white blood cell control) 13. Grade 2 or greater toxicities from prior therapy, except for Grade 2 toxicities that are not expected to resolve and that in the judgment of the Investigator do not pose a significant safety risk to subject participation. 14. Participants with any other medical condition, including mental illness or substance abuse, deemed by the Investigator to be likely to interfere with the participant's ability to sign the informed consent form or his/her ability to cooperate and participate in the study, or to interfere with the interpretation of the results.

• For patients enrolled on APEC14B1 prior to enrollment on AALL1631, the required diagnostic bone marrow sample has been fulfilled
• For patients who have not previously enrolled on APEC14B1 prior to enrollment on AALL1631, a baseline diagnostic sample (or peripheral blood sample with blasts if marrow sample unavailable) must be available to develop an MRD probe
• In addition, laboratory reports detailing evidence of BCR-ABL1 fusion must be submitted for rapid central review within 72 hours of study enrollment
• Newly diagnosed de novo ALL (B-ALL or T-ALL) or mixed phenotypic acute leukemia (MPAL meeting 2016 World Health Organization [WHO] definition) with definitive evidence of BCR-ABL1 fusion by karyotype, fluorescence in situ hybridization (FISH) and/or reverse transcriptase (RT)-PCR
• Patient must have previously started induction therapy, which includes vincristine, a corticosteroid, pegaspargase, with or without anthracycline, and/or other standard cytotoxic chemotherapy
• Patient has not received more than 14 days of multiagent induction therapy beginning with the first dose of vinCRIStine
• Patient may have started imatinib prior to study entry but has not received more than 14 days of imatinib
• Patients must have a performance status corresponding to Eastern Cooperative Oncology Group (ECOG) scores of 0, 1, or 2
• Direct bilirubin =< 2.0 mg/dL
• Shortening fraction of >= 27% by echocardiogram
• Ejection fraction of >= 50% by radionuclide angiogram or echocardiogram
• Corrected QT interval, QTc < 480 msec
• Note: Repeat echocardiogram is not required if echocardiogram was obtained within 21 days of study enrollment
• Creatinine clearance or radioisotope glomerular filtration rate (GFR) >= 70 mL/min/1.73 m^2
• Serum creatinine within normal limits based on age/gender, as follows:
• 1 to < 2 years: maximum serum creatinine 0.6 mg/dL (both male and female)
• 2 to < 6 years: maximum serum creatinine 0.8 mg/dL (both male and female)
• 6 to < 10 years: maximum serum creatinine 1 mg/dL (both male and female)
• 10 to < 13 years: maximum serum creatinine 1.2 mg/dL (both male and female)
• 13 to < 16 years: maximum serum creatinine 1.5 mg/dL (male), 1.4 mg/dL (female)
• >= 16 years: maximum serum creatinine 1.7 mg/dL (male), 1.4 mg/dL (female)
• Known history of chronic myelogenous leukemia (CML)
• ALL developing after a previous cancer treated with cytotoxic chemotherapy
• Active, uncontrolled infection, or active systemic illness that requires ongoing vasopressor support or mechanical ventilation
• Down syndrome
• Pregnancy and breast feeding
• 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
• Patients with congenital long QT syndrome, history of ventricular arrhythmias or heart block
• Prior treatment with dasatinib, or any BCR-ABL1 inhibitor other than imatinib
• All patients and/or their parents or legal guardians must sign a written informed consent
• All institutional, Food and Drug Administration (FDA), and National Cancer Institute (NCI) requirements for human studies must be met

1. Confirmed diagnosis of idiopathic SAA, defined as:
• Bone marrow cellularity <25%, or <30% hematopoietic cells.
• Two out of three of the following (in peripheral blood): neutrophils <0.5 x109/L, platelets <20 x109/L, reticulocyte count <60 x109/L with hemoglobin <8g/dL. 2. Age ≤25 years old. 3. No suitable fully matched related donor available (minimum 6/6 match for Human Leukocyte antigen (HLA) -A and B at intermediate or high resolution and DRB1 at high resolution using DNA based typing). 4. At least two unrelated donors noted on National Marrow Donor Program (NMDP) search who are well matched (9/10 or 10/10 for HLA-A, B, C, DRB1, and DQB1 using high resolution). 5. Signed informed consent for the randomized trial by patient and/or legal guardian. 6. Adequate organ function defined as in the judgment of the investigator, there is not irreversible organ damage that would preclude the patient from meeting the organ function inclusion criteria for HSCT listed in section 2.3.4 by the intended time of HSCT (6-8 weeks after randomization) or preclude patients from receiving horse ATG. 1. Inherited bone marrow failure syndromes (IBMFS). The diagnosis of Fanconi anemia must be excluded by diepoxybutane (DEB) or equivalent testing on peripheral blood or marrow. Telomere length testing should be sent on all patients to exclude Dyskeratosis congenita, but if results are delayed or unavailable and there are no clinical manifestations of DC, patients may enroll. If patients have clinical characteristics suspicious for Shwachman Diamond syndrome, this syndrome must be excluded by pancreatic isoamylase testing or gene mutation analysis. Note: pancreatic isoamylase testing is not accurate in children less than 3 years. 2. Clonal cytogenetic abnormalities or fluorescence In Situ Hybridization (FISH) pattern consistent with pre-myelodysplastic syndrome (pre-MDS) or MDS on marrow examination (see section 4.2.3.1 for details of the required MDS FISH panel). 3. Known severe allergy to horse ATG. 4. Prior allogeneic stem cell transplant. 5. Prior solid organ transplant. 6. Infection with human immunodeficiency virus (HIV). 7. Active Hepatitis B or C. This should be excluded in patients where there is clinical suspicion of hepatitis (e.g. elevated LFTs). 8. Female patients who are pregnant or breast-feeding. 9. Prior malignancies except resected basal cell carcinoma or treated cervical carcinoma in situ.

• Pathologically confirmed myelodysplastic syndrome (MDS) diagnosis (regardless of initial International Prognostic Scoring System [IPSS] risk category) or oligoblastic acute myeloid leukemia (AML) with 21-30% bone marrow (BM) blasts in whom DNMTi have failed; patients who have developed AML after DNMTi therapy can be enrolled as long as they have initiated DNMTi therapy while they were in the MDS or oligoblastic AML (20-30% BM blasts) phase and the study chair agrees; failure of DNMTis is defined as: failure to achieve a complete response (CR), partial response (PR) or hematologic improvement (HI) after at least 4 cycles of DNMTi or progressed after such therapy
• Eastern Cooperative Oncology Group (ECOG) performance status =< 2
• Calculated creatinine clearance by Modification of Diet in Renal Disease (MDRD) (CrCl) >= 60 ml/min/1.73 squared meter
• Total bilirubin =< 2.0 mg/dL unless due to Gilbert's syndrome, hemolysis, or ineffective hematopoiesis
• Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase [SGOT]) and alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) =< 3 x upper limit of normal (ULN)
• Females of childbearing potential must have a negative serum or urine pregnancy test within 72 hours prior to start of first cycle of therapy
• Patients must have no clinical evidence of central nervous system (CNS) or pulmonary leukostasis, disseminated intravascular coagulation, or CNS leukemia
• Patients must have no serious or uncontrolled medical conditions
• The effects of entinostat and MK-3475 (pembrolizumab) on the developing human fetus are unknown; for this reason, women of child-bearing potential and men who are sexually active with women of childbearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for 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 who are sexually active with women of childbearing potential, treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 4 months after completion of entinostat and MK3475 (pembrolizumab) administration
• Ability to understand and the willingness to sign a written informed consent document
• Patients, who relapsed 6 months after bone marrow transplant and have no evidence of active graft versus host disease and are off systemic immunosuppressant medications for at least 2 months and have received hypomethylating agents (HMA) therapy before or after transplant and meet other eligibility criteria of progression after at least 4 months of DNMTi therapy, are eligible to be enrolled in this clinical trial
• Any patients eligible for allogeneic stem cell transplantation (allo-SCT) and willing to undergo allo-SCT as determined at time of screening for trial; patients who are ineligible or not interested in undergoing allo-SCT will be eligible for the trial
• Any serious medical condition, uncontrolled intercurrent illness (e.g., active infection, symptomatic congestive heart failure [CHF], unstable angina, cardiac arrhythmias, laboratory abnormalities, or psychiatric illness and/or biopsychosocial conditions that may limit compliance
• Patients with known active cancers who are on therapy for those cancers at time of screening
• Patients who are human immunodeficiency virus (HIV) positive may participate IF they meet the following eligibility requirements:
• They must be stable on their anti-retroviral regimen, and they must be healthy from an HIV perspective
• They must have a CD4 count of greater than 250 cells/mcL
• They must not be receiving prophylactic therapy for an opportunistic infection; patients with a known positive test for hepatitis B virus surface antigen (HBV sAg) or hepatitis C virus ribonucleic acid (HCV antibody) indicating acute or chronic infection might be enrolled if the viral load by polymerase chain reaction (PCR) is undetectable with/without active treatment
• Pregnant or breast feeding females (lactating females must agree not to breast feed while taking the study drugs)
• Use of any other experimental drug or therapy within 21 days of baseline
•patients who have had chemotherapy or radiotherapy within 4 weeks of entering the study or those who have not recovered from adverse events due to agents administered more than 4 weeks earlier
• Known hypersensitivity to MK-3475 (pembrolizumab) or history of allergic reactions to compounds of similar chemical or biologic composition to anti-PD1 or PD-L1 antibodies or entinostat
• Prior treatment with any anti-PD-1 blocking therapies or histone deacetylase inhibitors (HDACi), or anti-CTLA-4 antibody, CD137 agonist or other immune activating therapy such as anti-CD 40 antibody within the last 3 months of enrollment in the study
• Any history of active or severe autoimmune disease: inflammatory bowel disease, including ulcerative colitis and Crohn's disease, rheumatoid arthritis, systemic progressive scleroderma, systemic lupus erythematosus, autoimmune vasculitis (e.g., Wegener's granulomatosis), CNS or motor neuropathy considered of autoimmune origin (e.g. Guillain-Barre syndrome, myasthenia gravis, multiple sclerosis); patients with hypothyroidism with stable hormone replacement therapy dosing are allowed on study
• Has a history of (non-infectious) pneumonitis that required steroids or has current pneumonitis