Inclusion Criteria:

• Participants who have received at least one dose of cilta-cel in a Company-sponsored clinical study
• Participants who have provided informed consent for this study

Inclusion Criteria:

Part 1 1. Written Informed Consent (mentally competent patient, able to understand and willing to sign the informed consent form) 2. Age ≥ 18 years, male or non-pregnant female 3. Able to comply with the study protocol, as per Investigator's judgment 4. Histologically confirmed, unresectable locally advanced or metastatic cancer. There are no limits to prior lines of therapies received for the treatment of the cancer condition for which the patient is being enrolled into this study. 1. For the Part 1 combination urothelial carcinoma Cohorts 13 and 14: histologically or cytologically confirmed diagnosis of unresectable, locally advanced or metastatic urothelial carcinoma of the renal pelvis, ureter, bladder, or urethra (i.e., transitional cell carcinoma). 2. For the Part 1 combination H/N cancer Cohorts 11 and 12: histologically confirmed, locally advanced or metastatic squamous cell carcinoma of head and neck (SCCHN; oral cavity, oropharynx, hypopharynx, or larynx). 5. For urothelial and H/N combination cancer cohorts, prior exposure to immunotherapy is allowed, with standard of care treatment options and/or within a clinical trial context. If the patient received an anti-PD-1 and/or an anti-PD-L1 containing regimen at any point, they must have demonstrated at least stable disease, as per RECIST 1.1 or iRECIST criteria to one of these treatment regimens, if these measurements are available. If RECIST or iRECIST measurements are not available, then clinical PFS of at least 4 months is required to have been achieved on any of the prior anti-PD-1 and/or anti-PD-L1 containing regimens. 6. There is no PD-L1 expression requirement for the Part 1 combination urothelial and H/N cohorts; however, fresh biopsy or archival tissue is required for assessment of PD-L1 by IHC, or a historical PD-L1 expression by IHC must be available. If PD-L1 expression data are already available, this does not override the protocol preference for obtaining a fresh biopsy whenever feasible. 7. For Part 1 combination cohort H/N cancer patients of oropharynx origin: human papilloma virus (HPV) status needs to be established in the screening period or at any point while patient is on study drug, unless it is historically known. p16+ as a surrogate for HPV+, HPV RNA ISH or DNA PCR are all acceptable. The study accepts both HPV+ and HPV- patients. 8. Life expectancy > 3 months according to Investigator's judgment 9. ECOG performance status 0-1 10. Patient able and willing to undergo pre- and on/post treatment biopsies. According to the Investigator's judgment, the planned biopsies should not expose the patient to substantially increased risk of complications. Every effort will be made that the same lesion is biopsied on repeat biopsies. If the patient is eligible according to all other criteria but declines to consent to a biopsy or there are other medical reasons precluding biopsy, this will be discussed with the Sponsor. 11. Measurable disease, according to RECIST v1.1. Note that lesions intended to be biopsied should not be target lesions. 12. Adequate hematologic and end organ function, defined by the following laboratory results obtained prior to first dose of study drug treatment, provided no anticancer treatment was administered within the last 7 days: 1. neutrophil count ≥ 1 x 109/L 2. platelet count ≥ 100 x 109/L; for hepatocellular carcinoma (HCC) in Part 1 ≥ 50 x 109/L 3. hemoglobin ≥ 9.0 g/dL without transfusion in the previous week 4. creatinine ≤ 1.5 x the upper limit of normal (ULN); or eGFR > 50 mg/mmol 5. aspartate aminotransferase AST (SGOT) ≤ 3 x ULN (≤ 5 x ULN when HCC or hepatic metastases are present) 6. alanine aminotransferase (ALT [SGPT]) ≤ 3 x ULN (≤ 5 x ULN when HCC or hepatic metastases present) 7. bilirubin ≤ 1.5 x ULN (patients with known Gilbert's disease may have a bilirubin ≤ 3.0 x ULN) 8. albumin ≥ 3.0 g/dL 9. international normalized ratio (INR) and partial thromboplastin time (PTT) ≤ 1.5 x ULN, unless patient receiving anticoagulant therapy 13. No evidence of active serious infection or infections requiring parenteral antibiotics. 14. Women of childbearing potential must have a negative pregnancy test within 72 h prior to start of treatment. For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or to use contraceptive methods that result in a failure rate of < 1% per year during the treatment period and for at least 180 days after the last study treatment. A woman is of childbearing potential if she is post-menarche, has not reached a postmenopausal state (≥ 12 continuous months of amenorrhea with no identified cause other than menopause), and has not undergone surgical sterilization (removal of ovaries and/or uterus). Examples of contraceptive methods with a failure rate of < 1% per year include bilateral tubal ligation, male sterilization, hormonal contraceptives that inhibit ovulation, hormone-releasing intrauterine devices and copper intrauterine devices. The reliability of sexual abstinence should be evaluated in relation to the duration of the clinical trial and the preferred and usual lifestyle of the patient. Periodic abstinence (e.g., calendar, ovulation, symptom-thermal, or post ovulation methods) and withdrawal are not acceptable methods of contraception. Fertile men must practice effective contraceptive methods during the study, unless documentation of infertility exists. 15. Four (4) weeks or 5 half-lives (whichever is shorter) since the last dose of anticancer therapy before the first LYT-200 administration 16. Bisphosphonate treatment (e.g., zoledronic acid) or denosumab are allowed if previously used prior to commencement of clinical trial. 17. Patients: 1. who have already received at least one prior line of systemic therapy for metastatic or locally advanced disease, and/or 2. who have a tumor type for which there are no available standard of care options 18. Patients who have not previously received a gemcitabine-containing regimen

Exclusion Criteria

1. Patient unwilling or unable to follow protocol requirements 2. Patient diagnosed with metastatic cancer of an unknown primary 3. Current illicit drug addiction (medical and recreational marijuana/cannabidiol [CBD]/ tetrahydrocannabinol [THC] would not be considered "illicit") 4. Clinically significant, active uncontrolled bleeding, and any patients with a bleeding diathesis (e.g., active peptic ulcer disease). Prophylactic or therapeutic use of anticoagulants is allowed. 5. Pregnant and/or lactating females 6. Receiving any other investigational agents or participating in any other clinical trial involving another investigational agent for treatment of solid tumors within 3 weeks or 5 half-lives of the administered drug (whichever is shorter) prior to the first dose of study drug, or major surgery or planned surgery within 4 weeks of the first dose of study drug (this includes dental surgery). 7. Radiation therapy within 4 weeks of the first dose of study drug, except for palliative radiotherapy to a limited field, such as for the treatment of bone pain or a focally painful tumor mass, and which does not jeopardize required measurable lesions for response assessment (RECIST v1.1). 8. Patients with fungating tumor masses 9. History or current evidence of any condition, therapy, any active infections, or laboratory abnormality that might confound the results of the trial, interfere with the patient's participation for the full duration of the trial, or is not in the best interest of the patient to participate, in the opinion of the treating Investigator 10. Grade 4 immune-mediated toxicities with a prior checkpoint inhibitor. Grade 2 or Grade 3 pneumonitis or any other Grade 3 checkpoint inhibitor-related toxicity that led to immunotherapy treatment discontinuation. Low-grade (< Grade 3) toxicities, such as neuropathy from prior treatments, manageable electrolyte abnormalities and lymphopenia, alopecia and vitiligo are allowed. 11. History of other prior or other concomitant malignancy that requires other active treatment. 12. Active parenchymal brain metastases, patients with carcinomatous meningitis or leptomeningeal metastases. Patients with brain metastases are eligible provided they have shown clinically and radiographically stable disease for at least 4 weeks after definitive therapy and have not used steroids (> 10 mg/day of prednisone or equivalent) for at least 4 weeks prior to the first dose of study drug 13. Evidence of severe or uncontrolled systemic diseases, congestive heart failure > New York Heart Association (NYHA) class 2, myocardial infarction (MI) within 6 months, or laboratory finding that in the view of the Investigator makes it undesirable for the patient to participate in the trial 14. Any medical condition that the Investigator considers significant to compromise the safety of the patient or that impairs the interpretation of LYT-200 toxicity assessment 15. Serious non-healing wound, active ulcer, or untreated bone fracture unless for e.g., a rib fracture for (which does not elicit treatment) 16. Uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent drainage procedures. For the purposes of this study, "recurrent" is defined as ³ 3 drains in the last 30 days 17. History of severe allergic, anaphylactic, or other hypersensitivity reactions to chimeric or humanized antibodies or fusion proteins 18. Significant vascular disease (e.g., aortic aneurysm requiring surgical repair or recent arterial thrombosis) within 6 months of Cycle 1, Day 1 19. History of pulmonary embolism, stroke or transient ischemic attack within 3 months prior to Cycle 1, Day 1 20. Active autoimmune disorder (except type I/II diabetes, hypothyroidism requiring only hormone replacement, vitiligo, psoriasis, or alopecia areata). 21. Requires systemic immunosuppressive treatment, including, but not limited to cyclophosphamide, azathioprine, methotrexate, thalidomide, and anti-tumor necrosis factor (anti-TNF) agents. Patients who have received or are receiving acute, low dose systemic immunosuppressant medications (e.g., ≤ 10 mg/day of prednisone or equivalent) may be enrolled. Replacement therapy (e.g., thyroxine, insulin, physiologic corticosteroid replacement therapy [e.g., ≤ 10 mg/day of prednisone equivalent] for adrenal or pituitary insufficiency) is not considered a form of systemic treatment. The use of inhaled corticosteroids and mineralocorticoids (e.g., fludrocortisone), topical steroids, intranasal steroids, intra-articular, and ophthalmic steroids is allowed. 22. Severe tumor-related pain (Grade 3, CTCAE v.5.0) unresponsive to broad analgesic interventions (oral and/or patches) 23. Hypercalcemia (defined as ³ Grade 3, per CTCAE v 5.0) despite use of bisphosphonates 24. Any other diseases, metabolic dysfunction, physical examination finding, or clinical laboratory finding giving reasonable suspicion of a disease or condition that contraindicates the use of an investigational drug or that may affect the interpretation of the results or render the patient at high risk of treatment complications 25. Received organ transplant(s) 26. Patients undergoing dialysis 27. For Part 1, hormonal androgen deprivation therapy is allowed to continue for patients with metastatic castration-resistant prostate cancer 28. Any ablative therapy (Radio Frequency Ablation or Percutaneous Ethanol Injection) for HCC < 6 weeks prior trial entry 29. Hepatic encephalopathy or severe liver adenoma 30. Child-Pugh score ≥ 7

Key Inclusion Criteria:

Subjects are eligible for enrollment into this study if they meet any of the following criteria (NOTE: This is not an exhaustive list):
• Subjects aged ≥18 years.
• ECOG performance status 0 or 1
• Subjects must have a documented IDH mutation per immunohistochemistry (IHC), polymerase chain reaction (PCR), or next generation sequencing (NGS) testing of tumor tissue.
• Subjects must have histologically or cytologically documented, advanced or metastatic solid malignancy of any type that has recurred or progressed on available standard treatment and for which no curative therapy exists.

Key Exclusion Criteria:

Subjects are not eligible for enrollment into this study if they meet any of the following criteria (NOTE: This is not an exhaustive list):
• Subjects who received an investigational agent <14 days prior to their first day of study drug administration
• Subjects who are pregnant or breastfeeding
• Subjects with an active severe infection, some treated infections and with an expected or with an unexplained fever >38.3°C during screening visits or on their first day of study drug administration.
• Subjects with some current or prior heart conditions
• Subjects taking medications that are known to prolong the QT interval may not be eligible
• Subjects with immediately life-threatening, severe complications of leukemia such as uncontrolled bleeding, pneumonia with hypoxia or shock, and/or disseminated intravascular coagulation
• Some subjects with some current or prior gastrointestinal or liver diseases
• Subjects with inadequate organ function as defined by the protocol

Inclusion Criteria

1. Patients in the Phase 1 dose-escalation portion must have a diagnosis of relapsed or refractory AML, ALL or acute leukemia of ambiguous lineage, as determined by pathology review at the treating institution, and who failed available standard therapies known to be active for their AML, ALL, or acute leukemia of ambiguous lineage. Enrollment to the phase 1 portion of the study may be limited to patients with certain genetic abnormalities. Patients in the Phase 2 dose-expansion portion must have a confirmed diagnosis of relapsed or refractory AML, as determined by pathology review at the treating institution, and who failed available standard therapies known to be active for their AML. They must also have a documented KMT2A (MLL)-fusion or NPM1 mutation, which includes those with coexisting FLT3 genomic alterations and/or IDH1/2 mutations. 2. Be > 18 years of age or 20 years if required by local regulation 3. ECOG < 2 4. WBC below 30,000/μL (hydroxyurea allowed prior to initiation of the study treatment) 5. Clearance of creatinine (CLcr) level ≥ 50 ml/min, assessed by the Cockcroft-Gault formula 6. Total bilirubin ≤1.5 the upper limit of normal (ULN) (or ≤2.0 ULN for patients with known Gilbert's syndrome) 7. Aspartate aminotransferase (AST) ≤3.0 times ULN 8. Alanine aminotransferase (ALT) ≤3.0 times ULN 9. Any prior treatment-related toxicities resolved to ≤Grade 1 prior to enrollment, with the exception of ≤Grade 2 alopecia or neuropathy. 10. Be willing to attend study visits as required by the protocol 11. Have an estimated life expectancy ≥3 months, based on the investigator's assessment 12. Females of childbearing potential must have a negative serum pregnancy test. Females of childbearing potential are defined as women who have (1) experienced menarche and have not undergone sterilization procedures (hysterectomy, bilateral tubal ligation, or bilateral oophorectomy), or have (2) not experienced menopause (defined as having amenorrhea continuously for more than 12 months that is not determined to be drug-induced, or who are taking hormone replacement therapy with serum follicle-stimulating hormone > 35 mlU/ml). 13. Must agree to use a combination of 2 or more different contraception methods (oral contraceptives/implantable hormonal contraceptives*, and barrier method*) or use prevention of pregnancy measures (ie, agreement to refrain completely from heterosexual intercourse) during the study and for 6 months (for females and males alike) after the last dose of study drug, if male or female patient of child-producing potential 14. Have AML/ALL material suitable for genomic analysis of AML or ALL genetic alterations

Exclusion Criteria:

1. Has a left ventricular ejection fraction (LVEF) <45%, as determined by ECHO 2. Histological diagnosis of acute promyelocytic leukemia 3. Received systemic calcineurin inhibitors within 4 weeks prior to the first dose of DSP 5336 4. Has had abnormal ECGs that are clinically significant, such as QT prolongation (QTc >450 msec for males and >470 msec for females, with QTc corrected according to Fridericia's formula [QTcF]) 5. Has an active, uncontrolled, bacterial, viral, or fungal infection requiring systemic therapy 6. Receives concurrent sensitive substrates with a narrow safety window or strong inhibitors or inducers of CYP3A4/5, including specifically: ketoconazole and itraconazole. Other antifungals that are used as standard of care to prevent or treat infections are permitted. If a patient is on one of the excluded azole class antifungals, he/she can be taken off or switched to a permitted azole 7 or more days prior to first dose, then the patient could be allowed on study (Arm B) with approval of the medical monitor. 7. Received immunotherapy, including tumor vaccines and checkpoint inhibitors, within 42 days prior to the first dose of DSP-5336 8. Has been on other investigational treatment within the previous 4 weeks prior to the first dose of DSP-5336 9. Had major surgery within 28 days prior to the first dose of DSP-5336 10. Has active central nervous system leukemia 11. Previously received menin-MLL inhibitors 12. Has immediately life threatening or severe complications of leukemia 13. Underwent HSCT or chimeric antigen receptor cell (CAR-T) therapy or other modified T-cell therapy within 60 days prior to the first dose of DSP-5336 14. Received a donor lymphocyte infusion within 28 days prior to the first dose of DSP-5336, or receiving immunosuppressive therapy post-HSCT at the time of screening, or with clinically active GVHD or GVHD requiring active medical intervention other than the use of topical steroids for ongoing cutaneous GVHD 15. Received antineoplastic agents (except hormonal therapies as adjuvant maintenance for breast or prostate cancers if a patient is taking before starting study treatment, and hydroxyurea given for controlling blast cells) within 14 days prior to the first dose of DSP-5336 16. Received anthracycline where cumulative doses exceeded the upper limit per the label approved in each country or investigator discretion (if there is no label restriction, investigator must state the cumulative dose received for each patient and sign to indicate that, in his/her medical opinion, stated prior dose of the agent does not put patient at undue risk of anthracycline-related cardiotoxicity 17. In the opinion of the treating investigator, have any concurrent conditions that could pose an undue medical hazard or interfere with interpretation of study results; these conditions include, but are not limited to: clinically significant non-healing or healing wounds; concurrent congestive heart failure; concurrent unstable angina; concurrent cardiac arrhythmia requiring treatment (excluding asymptomatic atrial fibrillation); recent (within the prior 6 months) myocardial infarction; acute coronary syndrome within the previous 6 months; significant pulmonary disease (shortness of breath at rest or on mild exertion), eg, due to concurrent severe obstructive pulmonary disease, concurrent hypertension not controlled with concomitant medication, or diabetes mellitus with more than 2 episodes of ketoacidosis in the prior 6 months 18. Have an active acute or chronic infection, including human immunodeficiency virus (HIV) as determined by anti-HIV antibodies; and hepatitis B virus (HBV) or hepatitis C virus (HCV) as determined by hepatitis B surface antigen (HBsAg) or anti-HCV antibodies, respectively. For sites in Japan only: Hepatitis B core (HBc) antibody or hepatitis B surface (HBs) antibody test should be performed if HBsAg is negative. If HBc antibody or HBs antibody test is positive, HBV DNA quantification test should be performed to confirm that HBV DNA is negative. 19. Have advanced liver disease or cirrhosis (Child-Pugh's Class B or greater) 20. Have one or more active autoimmune diseases requiring immunosuppressive therapy other than low-dose corticosteroids (equivalent to prednisone 10mg daily) or azathioprine. Patients on stable immunomodulatory medications may be considered by the investigator 21. Have active (uncontrolled, metastatic) malignancies of another type 22. Have severe dysphagia, short-gut syndrome, gastroparesis, or other conditions that limit the ingestion or gastrointestinal absorption of drugs administered orally, including the inability to swallow oral medication 23. Have cognitive, psychologic, or psychosocial impediment that would impair the ability of the patient o receive therapy according to the protocol, or adversely affect the ability of the patient to comply with the informed consent process, protocol, or protocol-required visits and procedures 24. Are pregnant or breastfeeding or planning to become pregnant Note: Patients who are breastfeeding may be enrolled if they interrupt breastfeeding prior to the first dose of any study drugs and do not feed the baby with breast milk expressed after receiving the first dose of any study drugs. Breastfeeding should not be resumed for at least 6 months after the last dose of study drug 25. Have any history or complication of interstitial lung disease (for sites in Japan only) 26. Have a history of Torsades de Pointes

Inclusion Criteria:

• Documented multiple myeloma as defined: a) Multiple myeloma diagnosis according to the International Myeloma Working Group (IMWG) diagnostic criteria and b) Measurable disease at screening as defined by any of the following: i) Serum M-protein level greater than or equal to (>=) 0.5 grams per deciliter (g/dL) (central laboratory); ii) Urine M-protein level >= 200 milligram (mg) per 24 hours (central laboratory); iii) Light chain multiple myeloma without measurable M-protein in the serum or the urine: serum immunoglobulin free light chain >= 10 milligram per deciliter (mg/dL) (central laboratory), and abnormal serum immunoglobulin kappa lambda free light chain ratio
• Received at least 1 prior line of antimyeloma therapy including a proteasome inhibitor (PI) and lenalidomide. Participants who have received only 1 prior line of antimyeloma therapy must be considered lenalidomide-refractory (that is, have demonstrated progressive disease by IMWG criteria on or within 60 days of completion of lenalidomide-containing regimen). Participants who have received >=2 prior lines of antimyeloma therapy must be considered lenalidomide exposed
• Documented evidence of progressive disease based on investigator's determination of response by the IMWG criteria on or after their last regimen
• Have an Eastern Cooperative Oncology Group (ECOG) performance status score of 0, 1, or 2 at screening and immediately prior to the start of administration of study treatment

Exclusion Criteria:

• Contraindications or life-threatening allergies, hypersensitivity, or intolerance to study drug excipients
• Disease is considered refractory to an anti-cluster of differentiation 38 (CD38) monoclonal antibody as defined per IMWG consensus guidelines (progression during treatment or within 60 days of completing therapy with an anti-CD38 monoclonal antibody)
• A maximum cumulative dose of corticosteroids to >=140 milligrams (mg) of prednisone or equivalent within 14-day period before the first dose of study drug
• Known active central nervous system (CNS) involvement or exhibits clinical signs of meningeal involvement of multiple myeloma. If either is suspected, negative whole brain magnetic resonance imaging (MRI) and lumbar cytology are required
• Plasma cell leukemia (per IMWG criteria) at the time of screening, Waldenström's macroglobulinemia, polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS syndrome), or primary amyloid light chain amyloidosis

Inclusion Criteria:

• 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.
• 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 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.

Exclusion Criteria:

• 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.
• Patients who have received > 72 hours of hydroxyurea within 1 week (7 days) prior to the start of systemic protocol therapy.
• 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 known MYC translocation associated with mature (Burkitt) B-cell ALL, regardless of blast immunophenotype.
• Patients requiring radiation at diagnosis.
• 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.

Inclusion Criteria:

• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Relapsed or refractory ALL after multi-agent chemotherapy (>= 5% marrow lymphoblasts, assessed by morphology and flow cytometry; flow cytometry will be used to confirm immunophenotype and percentage of blasts will be assessed by morphology)
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Eastern Cooperative Oncology Group (ECOG) performance status 0-2
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Adequate liver function with aspartate aminotransferase (AST)/alanine aminotransferase (ALT) less than 3 X upper limit of normal and total bilirubin less than 2 mg/dL within 7 days prior to first dose of study agent
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Circulating white blood cell (WBC) count must not be above 20 x10^9/L within 7 days prior to first dose of study agent
• Patients with WBC count above 20 x 10^9/L may be eligible if they start steroids or hydroxyurea per institutional guidelines, but they must discontinue before day 1 of study drug
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Creatinine clearance of at least 50 mL/min within 7 days prior to first dose of study agent
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Women must not be pregnant or breast-feeding
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): All females of childbearing potential must have a blood test or urine study within 2 weeks prior to registration to rule out pregnancy; a female of childbearing potential is any woman, regardless of sexual orientation or whether they have undergone tubal ligation, who meets the following criteria: 1) has not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been naturally postmenopausal for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months)
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Women of childbearing potential and sexually active males must use an accepted and highly effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study and for 30 days after the last dose of venetoclax; should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she (or the participating partner) should inform the treating physician immediately
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): No evidence of prior malignancy except adequately treated non-melanoma skin cancer, in situ cervical carcinoma, or any surgically- or radiation-cured malignancy continuously disease free for >= 5 years so as not to interfere with interpretation of radiographic response
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): No evidence of isolated extramedullary relapse (i.e., testicular or central nervous system [CNS])
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Patient must not have Burkitt?s lymphoma/leukemia based on the World Health Organization (WHO) criteria
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Patients must not have active central nervous system (CNS) leukemia, as defined by unequivocal morphologic evidence of lymphoblasts in the cerebrospinal fluid (CSF), use of CNS-directed local treatment for active disease within the prior 28 days; previously treated CNS disease with documented cleared CSF will be allowed
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Patient will not be enrolled if they received prior chemotherapy within 2 weeks before enrollment with the following exceptions: to reduce the circulating lymphoblast count or palliation (i.e., steroids or hydroxyurea) or for ALL maintenance (mercaptopurine, methotrexate, vincristine, thioguanine, and/or tyrosine kinase inhibitors)
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Patient may be enrolled with a prior allogeneic hematopoietic stem cell transplant (HSCT) but the transplant date must be at least 90 days before date of enrollment; patient must be off immunosuppression and without active graft versus host disease (GVHD) prior to enrollment if previous HSCT
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Patient cannot have poorly controlled human immunodeficiency virus (HIV), or CD4 < 400; HIV positive patients are allowed on this study if they have a CD4 count >= 400, and are on a stable antiviral regimen
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Patients with New York Heart Association (NYHA) class III or IV heart failure, uncontrolled angina, severe uncontrolled ventricular arrhythmias, or electrocardiographic evidence of acute ischemia may not be enrolled
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Patients with serious medical or psychiatric illness that in the opinion of the primary investigator is likely to interfere with study participation may not be enrolled
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Patients must not be participating in any other clinical trial or taking any other experimental medications within 21 days prior to registration
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Patients should not have received the following within 7 days prior to the first dose of study drug:
• Steroid therapy for anti-neoplastic intent;
• Strong and moderate CYP3A inhibitors;
• Strong and moderate CYP3A inducers
• ELIGIBILITY CRITERIA - PHASE I (ARMS A, B, C): Patients must not have grade 3 or higher peripheral neuropathy
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Relapsed or refractory ALL after multi-agent chemotherapy (>= 5% marrow lymphoblasts, assessed by morphology and flow cytometry; flow cytometry will be used to confirm immunophenotype and percentage of blasts will be assessed by morphology)
• ELIGIBILITY CRITERIA - PHASE II (ARM D): ECOG performance status 0-2
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Adequate liver function with AST/ALT less than 3 X upper limit of normal and total bilirubin less than 2 mg/dL within 7 days prior to first dose of study agent
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Circulating WBC count must not be above 20 x10^9/L within 7 days prior to first dose of study agent
• Patients with WBC count above 20 x10^9/L may be eligible if they start steroids or hydroxyurea per institutional guidelines, but they must discontinue before day 1 of study drug
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Creatinine clearance of at least 50 mL/min within 7 days prior to first dose of study agent
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Women must not be pregnant or breast-feeding
• ELIGIBILITY CRITERIA - PHASE II (ARM D): All females of childbearing potential must have a blood test or urine study within 2 weeks prior to registration to rule out pregnancy; a female of childbearing potential is any woman, regardless of sexual orientation or whether they have undergone tubal ligation, who meets the following criteria: 1) has not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been naturally postmenopausal for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months)
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Women of childbearing potential and sexually active males must use an accepted and highly effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study and for 30 days after the last dose of venetoclax; should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she (or the participating partner) should inform the treating physician immediately
• ELIGIBILITY CRITERIA - PHASE II (ARM D): No evidence of prior malignancy except adequately treated non-melanoma skin cancer, in situ cervical carcinoma, or any surgically- or radiation-cured malignancy continuously disease free for >= 5 years so as not to interfere with interpretation of radiographic response
• ELIGIBILITY CRITERIA - PHASE II (ARM D): No evidence of isolated extramedullary relapse (i.e., testicular or CNS)
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Patient must not have Burkitt?s lymphoma/leukemia based on the WHO criteria
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Patients must not have active central nervous system (CNS) leukemia, as defined by unequivocal morphologic evidence of lymphoblasts in the cerebrospinal fluid (CSF), use of CNS-directed local treatment for active disease within the prior 28 days; previously treated CNS disease with documented cleared CSF will be allowed
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Patient will not be enrolled if they received prior chemotherapy within 2 weeks before enrollment with the following exceptions: to reduce the circulating lymphoblast count or palliation (i.e., steroids or hydroxyurea), for ALL maintenance (mercaptopurine, methotrexate, vincristine, thioguanine, and/or tyrosine kinase inhibitors)
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Patient may be enrolled with a prior allogeneic hematopoietic stem cell transplant (HSCT) but the transplant date must be at least 90 days before date of enrollment; patient must be off immunosuppression and without active GVHD prior to enrollment if previous HSCT
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Patient cannot have poorly controlled HIV, or CD4 < 400; HIV positive patients are allowed on this study if they have a CD4 count >= 400, and are on a stable antiviral regimen
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Patients with NYHA class III or IV heart failure, uncontrolled angina, severe uncontrolled ventricular arrhythmias, or electrocardiographic evidence of acute ischemia may not be enrolled
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Patients with serious medical or psychiatric illness that in the opinion of the primary investigator is likely to interfere with study participation may not be enrolled
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Patients must not be participating in any other clinical trial or taking any other experimental medications within 21 days prior to registration
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Patients should not have received the following within 7 days prior to the first dose of study drug:
• Steroid therapy for anti-neoplastic intent;
• Strong and moderate CYP3A inhibitors;
• Strong and moderate CYP3A inducers
• ELIGIBILITY CRITERIA - PHASE II (ARM D): Patients must not have grade 3 or higher peripheral neuropathy

Inclusion Criteria:

• Participants must have histologically or cytologically confirmed diffuse large B-cell lymphoma (DLBCL), Ann Arbor Stage IIX (bulky), III or IV. Participants with DLBCL transformed from follicular lymphoma (FL) or marginal zone lymphoma (MZL, including mucosa-associated lymphoid tissue [MALT] lymphomas), lymphoplasmacytic lymphoma (LPL), or nodular lymphocyte-predominant Hodgkin Lymphoma (NLPHL) are eligible. Participants with Grade IIIB follicular lymphoma (FL) or high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements are also eligible. Participants with DLBCL that arose from prior CLL (Richter's transformation) are not eligible.
• As defined by the World Health Organization (WHO), eligible lymphoma subtypes include the following:
• DLBCL, not otherwise specified (NOS)
• DLBCL, germinal-center B-cell type (GCB)
• DLBCL, activated B-cell type (ABC)
• T-cell histiocyte-rich B-cell lymphomas (THRBCL)
• Primary cutaneous DLBCL, leg type
• Intravascular large B cell lymphoma
• EBV+ DLBCL, NOS
• DLBCL associated with chronic inflammation
• HHV8+ DLBCL, NOS
• High-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements
• High grade B-cell lymphoma, NOS
• Follicular lymphoma grade 3b
• Participants must have staging imaging performed within 28 days prior to registration, as follows. Positron emission tomography (PET)-computed tomography (CT) baseline scans are strongly preferred; diagnostic quality magnetic resonance imaging (MRI), contrast-enhanced CT, or contrast-enhanced MRI scans are also acceptable if PET-CT is not feasible at baseline. Note: PET-CT will be required at end of treatment (EOT) and progression for response assessment. All measurable lesions (longest diameter >= 1.5 cm) must be assessed within 28 days prior to registration. Tests to assess non-measurable disease must be performed within 42 days prior to registration.
• Participants with known human immunodeficiency virus (HIV)-infection are eligible providing they are on effective anti-retroviral therapy and have undetectable viral load at their most recent viral load test (must be within 26 weeks prior to registration). Participants with known HIV must have a CD4 count checked within 28 days prior to registration, but may proceed with therapy regardless of CD4 count.
• All participants must be screened for chronic hepatitis B virus (HBV) within 28 days prior to registration. Participants with known HBV infection (positive serology) must also have a HBV viral load performed within 28 days prior to registration, and participants must have an undetectable HBV viral load on suppressive therapy within 28 days prior to registration. Participants found to be HBV carriers during screening are eligible and must receive standard of care prophylaxis. Participants with active hepatitis B (HBV viral load > 500 IU/mL) within 28 days prior to registration are not eligible
• Participants with a known history of hepatitis C virus (HCV) infection must have an undetectable HCV viral load within in 28 days prior to registration
• Participants must have a Zubrod performance status of 0-2
• Participants must have adequate renal function, as demonstrated by a creatinine clearance, calculated by the Cockcroft and Gault formula, of >= 30 ml/min that was obtained within 28 days prior to registration
• Aspartate aminotransferase (AST) =< 2.5 x institutional upper limit of normal (IULN), alanine aminotransferase (ALT) =< 2.5 x IULN (within 28 days prior to registration)
• Total bilirubin =< 2 x institutional upper limit of normal (IULN), unless due to Gilbert's disease, hemolysis, or lymphomatous involvement of liver (within 28 days prior to registration). Note: If total bilirubin is elevated, and direct bilirubin is subsequently performed (within 28 days prior to registration) and resulted to be =< 2 x IULN, the participant will be considered eligible
• Absolute neutrophil count (ANC) >= 1000/mcL (within 28 days prior to registration)
• Platelets >= 75,000/mcL (within 28 days prior to registration)
• Hemoglobin (Hgb) >= 8 g/ dL (within 28 days prior to registration)
• If there is a documented lymphomatous involvement of the bone marrow, bone marrow function within 28 days prior to registration, as evidenced by:
• ANC >= 500/mcL
• Platelets >= 50,000/mcL
• Hemoglobin (Hgb) >= 8 g/ dL
• Participants must have a left ventricular ejection (LVEF) fraction >= 45% as measured by echocardiogram or radionuclide (multigated acquisition scan [MUGA]) ventriculography within 56 days prior to registration
• For the duration of the study treatment period and for at least 4 months following the last dose of study drug, male participants must agree to use effective contraceptive methods during sexual contact with a female of childbearing potential (FCBP) and must agree to refrain from semen or sperm donation during the same timeframe. Effective contraceptive methods include a history of vasectomy, use of hormonal contraception or an intrauterine device (IUD) by the female partner, or use of condoms
• A FCBP is a sexually mature woman who: 1) has not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been naturally postmenopausal for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months)

Exclusion Criteria:

• Participants must not have known lymphomatous involvement of the central nervous system (CNS)
• Participants must not have active inflammatory bowel disease (such as, Crohn's disease, ulcerative colitis), celiac disease (i.e., sprue), prior gastrectomy or upper bowel removal, or any other gastrointestinal disorder or defect that would interfere with the absorption, distribution, metabolism, or excretion of the study drug and/or predispose the subject to an increased risk of gastrointestinal toxicity
• Participants must not have received any prior cytotoxic chemotherapy or rituximab for treatment of the newly diagnosed DLBCL except for the pre-phase treatment (within specified dose range) that may have either started before or may start after registration to S1918. Inhaled, nasal, and topical steroid use is allowed. Prior cytotoxic chemotherapy and/or antibody therapy for an indolent lymphoma prior to transformation is allowed. Up to 4 doses of intrathecal (IT) chemotherapy administered for central nervous system (CNS) prophylaxis is allowed in addition to protocol therapy. High-dose intravenous methotrexate is not allowed.
• Participants must not have received more than a cumulative of dose 250 mg/m^2 of prior doxorubicin (or equivalent dose of another anthracycline, such as epirubicin) therapy (at any time prior to registration).
• Participants must not currently be receiving any other investigational agents
• Participant must not have a history of allergic reactions attributed to azacitidine, mannitol, or other hypomethylating agents
• Participants must not have active infection (systemic fungal, bacterial, or viral infection) that is not controlled (defined as ongoing signs/symptoms related the infection without improvement despite appropriate antibiotics, antiviral therapy, and/or other treatment)
• Participants must not have active cardiac disease within 26 weeks prior to registration, including: symptomatic congestive heart failure (New York Heart Association [NYHA] class 4), unstable angina pectoris, hemodynamically unstable cardiac arrhythmia, or myocardial infarction
• Participants must not have >= grade 2 neuropathy, by Common Terminology Criteria for Adverse Events (CTCAE) version (v.) 5.0, within 28 days prior to registration
• Participants must not have any other known uncontrolled intercurrent illness including, but not limited to ongoing psychiatric illness/social situations that would limit compliance with study requirements

Inclusion Criteria:

• Patients must be 5 to 60 years of age at the time of enrollment
• Patients with newly diagnosed untreated histologically confirmed classic Hodgkin lymphoma (cHL) (nodular sclerosis, mixed cellularity, lymphocyte-rich, or lymphocyte-depleted, or not otherwise specified [NOS]) with stage I or II disease
• Patients must have bidimensionally measurable disease (at least one lesion with longest diameter >= 1.5 cm)
• Patients must have a whole body or limited whole body PET scan performed within 42 days prior to enrollment. PET-CT is strongly preferred. PET-MRI allowed if intravenous contrast enhanced CT is also obtained
• Pediatric patients (age 5-17 years) must have an upright posteroanterior (PA) chest X-ray (CXR) for assessment of bulky mediastinal disease. Adult patients must have either a CXR or CT chest
• Patients >= 18 years must have a performance status corresponding to Zubrod scores of 0, 1 or 2
• Patients =< 17 years of age must have a Lansky performance score of >= 50
• Pediatric patients (age 5-17 years): A serum creatinine based on age/gender as follows (within 7 days prior to enrollment):
• 2 to < 6 years (age): 0.8 mg/dL (male), 0.8 mg/dL (female)
• 6 to < 10 years (age): 1 mg/dL (male), 1 mg/dL (female)
• 10 to < 13 years (age): 1.2 mg/dL (male), 1.2 mg/dL (female)
• 13 to < 16 years (age): 1.5 mg/dL (male), 1.4 mg/dL (female)
• >= 16 years (age): 1.7 mg/dL (male), 1.4 mg/dL (female) OR a 24 hour urine creatinine clearance >= 50 mL/min/1.73 m^2 (within 7 days prior to enrollment) OR a glomerular filtration rate (GFR) >= 50 mL/min/1.73 m^2 (within 7 days prior to enrollment). GFR must be performed using direct measurement with a nuclear blood sampling method OR direct small molecule clearance method (iothalamate or other molecule per institutional standard)
• Note: Estimated GFR (eGFR) from serum or plasma creatinine, cystatin C or other estimates are not acceptable for determining eligibility
• For adult patients (age 18 years or older) (within 7 days prior to enrollment): Creatinine clearance >= 30 mL/min, as estimated by the Cockcroft and Gault formula or a 24-hour urine collection. The creatinine value used in the calculation must have been obtained within 28 days prior to registration. Estimated creatinine clearance is based on actual body weight
• Total bilirubin =< 2 x upper limit of normal (ULN) (within 7 days prior to enrollment)
• Unless due to Gilbert's disease, lymphomatous involvement of liver or vanishing bile duct syndrome
• Aspartate aminotransferase (AST) =< 3 x ULN (within 7 days prior to enrollment)
• Unless due to Gilbert's disease, lymphomatous involvement of liver or vanishing bile duct syndrome
• Alanine aminotransferase (ALT) =< 3 x ULN (within 7 days prior to enrollment)
• Unless due to Gilbert's disease, lymphomatous involvement of liver or vanishing bile duct syndrome
• Shortening fraction of >= 27% by echocardiogram (ECHO), multigated acquisition scan (MUGA), or functional cardiac imaging scan (within 7 days prior to enrollment) or ejection fraction of >= 50% by radionuclide angiogram, ECHO, MUGA, or cardiac imaging scan (within 7 days prior to enrollment)
• Diffusion capacity of the lung for carbon monoxide (DLCO) >= 50% of predicted value as corrected for hemoglobin by pulmonary function test (PFT) (within 7 days prior to enrollment). If unable to obtain PFTs, the criterion is: a pulse oximetry reading of > 92% on room air
• Known human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial
• For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated. Patients with a history of hepatitis C virus (HCV) infection must have been treated and cured. For patients with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load

Exclusion Criteria:

• Patients with nodular lymphocyte predominant Hodgkin lymphoma
• Patients with a history of active interstitial pneumonitis or interstitial lung disease
• Patients with a diagnosis of inherited or acquired immunodeficiency that is poorly controlled or requiring active medications, such as primary immunodeficiency syndromes or organ transplant recipients
• Patients with any known uncontrolled intercurrent illness that would jeopardize the patient's safety such as infection, autoimmune conditions, cardiac arrhythmias, angina pectoris, and gastrointestinal disorders affecting swallowing and/or absorption of pills
• Patients with a condition requiring systemic treatment with either corticosteroids (defined as equivalent to > 10 mg daily prednisone for patients >= 18 years or > 0.5 mg/kg [up to 10 mg/day] for patients < 18 years) or other immunosuppressive medications within 14 days prior to enrollment
• Note: Replacement therapy such as thyroxine, insulin, or physiologic corticosteroid for adrenal or pituitary insufficiency is not considered a form of systemic treatment. Inhaled or topical steroids, and adrenal replacement doses (=< 10 mg daily for patients >= 18 years or =< 0.5 mg/kg [up to 10 mg/day] prednisone equivalents) are permitted in the absence of active autoimmune disease
• Note: Steroid use for the control of Hodgkin lymphoma symptoms is allowable, but must be discontinued by cycle 1, day 1
• Patients with peripheral neuropathy > grade 1 at the time of enrollment or patients with known Charcot-Marie-Tooth syndrome
• Patients with a prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the safety or efficacy assessment of the investigational regimen
• Administration of prior chemotherapy, radiation, or antibody-based treatment for cHL
• Prior solid organ transplant
• Prior allogeneic stem cell transplantation
• Live vaccine within 30 days prior to planned day 1 of protocol therapy (e.g., measles, mumps, rubella, varicella, yellow fever, rabies, bacillus calmette guerin [BCG], oral polio vaccine, and oral typhoid). Administration of messenger ribonucleic acid (mRNA) vaccines are permitted
• Female patients who are pregnant since fetal toxicities and teratogenic effects have been noted for several of the study drugs. A pregnancy test within 28 days prior to enrollment is required for female patients of childbearing potential
• Lactating females who plan to breastfeed their infants starting with the first dose of study therapy and for at least 6 months after the last treatment
• Sexually active patients of reproductive potential who have not agreed to use a highly effective contraceptive method (failure rate of < 1% per year when used consistently and correctly) for the duration of their study drug therapy. Following therapy, patients will be advised to use contraception as per institutional practice or as listed below for investigational agents, whichever is longer
• Men and women of childbearing potential must continue contraception for a period of 6 months after last dose of brentuximab vedotin
• Women of child-bearing potential (WOCBP) must continue contraception for a period of at least 5 months after the last dose of nivolumab
• 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

Inclusion Criteria:

• Age >= 2 years
• Patient must have histologically confirmed primary mediastinal B-cell lymphoma (PMBCL) as defined by World Health Organization (WHO) criteria
• Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2 or ECOG performance status of 3 if poor performance is related to lymphoma
• Children's Oncology Group (COG) Institutions: Use Karnofsky for patients >= 17 and < 18 years of age and Lansky for patients < 17 years of age
• Adults (age 18 or older): Creatinine clearance >= 30 mL/min, as estimated by the Cockcroft and Gault formula. The creatinine value used in the calculation must have been obtained within 28 days prior to registration. Estimated creatinine clearance is based on actual body weight
• Pediatric Patients (age < 18 years): The following must have been obtained within 14 days prior to registration:
• Measured or calculated (based on institutional standard) creatinine clearance or radioisotope glomerular filtration rate (GFR) >= 70 ml/min/1.73 m^2, or
• Serum creatinine =< 1.5 x institutional upper limit of normal (IULN), or a serum creatinine based on age/gender as follows:
• Age : 2 to < 6 year; Maximum serum creatinine (mg/dL): 0.8 (male; 0.8 (female)
• Age : 6 to < 10 years; Maximum serum creatinine (mg/dL): 1 (male); 1 (female)
• Age : 10 to < 13 years; Maximum serum creatinine (mg/dL): 1.2 (male); 1.2 (female)
• Age : 13 to < 16 years; Maximum serum creatinine (mg/dL): 1.5 (male); 1.4 (female)
• Age : >= 16 years to < 18 years; Maximum serum creatinine (mg/dL): 1.7 (male); 1.4 (female)
• Patients with abnormal liver function will be eligible to enroll if the lab abnormality is thought to be due to the lymphoma or Gilbert's syndrome
• Age >= 18 years: Ejection fraction of >= 50% by echocardiogram
• Age < 18 years: Shortening fraction of >= 27% by echocardiogram, or ejection fraction of >= 50% by radionuclide angiogram
• Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial
• For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated
• Patients with a history of hepatitis C virus (HCV) infection must have been treated and cured. For patients with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load
• 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

Exclusion Criteria:

• Administration of prior anti-cancer therapy except as outlined below:
• A short course (=< 2 weeks) of corticosteroids for the relief of lymphoma-related symptoms
• A single course of COP (cyclophosphamide, vincristine, and prednisone)
• One cycle of chemo-immunotherapy including R-CHOP, DA-EPOCH-R, a pediatric mature B-cell non-Hodgkin lymphoma (B-NHL) induction therapy (such as ANHL1131), or intrathecal chemotherapy that has not started more than 21 days prior to enrollment
• Active ischemic heart disease or heart failure
• Active uncontrolled infection
• Central nervous system (CNS) involvement of lymphoma
• Previous cancer that required systemic chemotherapy and/or thoracic radiation. Other cancers will be permitted if in remission x 3 years
• Active autoimmune disease that has required systemic treatment (such as disease modifying agents, corticosteroids, or immunosuppressive agents) in the past 2 years. Replacement therapy such as thyroxine, insulin or physiologic corticosteroid for adrenal or pituitary insufficiency is not considered a form of systemic treatment
• In patients < 18 years of age hepatitis B serologies consistent with past or current infections
• Patients with severe hepatic impairment (Child-Pugh class C or serum total bilirubin > 5.0 mg/dL) unless thought to be due to lymphoma or Gilbert's syndrome
• 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
• Sexually active patients of reproductive potential who have not agreed to use a highly effective contraceptive method (failure rate of < 1% per year when used consistently and correctly) for the duration of their study participation
• Lactating females are not eligible unless they have agreed not to breastfeed their infants starting with the first dose of study therapy and for at least 6 months after the last dose of rituximab

Inclusion Criteria:

• INCLUSION CRITERIA FOR SCREENING (STEP 0 - PREREGISTRATION)
• Patients must have histologically confirmed mantle cell lymphoma, with cyclin D1 by immunohistochemical stains and/or t(11;14) by cytogenetics or FISH. If patient has cyclin D1 negative mantle cell lymphoma with classical morphology and an expression profile (including SOX11+) that is otherwise indistinguishable from mantle cell lymphoma, communication with investigator is required for consideration of enrollment. The proliferation rate, using Ki-67 or MIB-1, should also be determined, but is not required until Step 1 registration. Patients may register to Step 0 without a documented Ki-67 index.
• Patients should be deemed to be potentially eligible and willing candidates for auto-HCT by the enrolling physician
• Patient may be receiving or have completed induction therapy within 60 days prior to preregistration to step 0; no more than 300 days may have passed between the first day of induction therapy and preregistration to step 0
• For patients who have completed induction therapy, restaging evaluation must show status of partial (PR) or complete response (CR); patients preregistered post-induction with evidence of clinical disease progression are not eligible for preregistration
• Up to two regimens of chemotherapy are allowed as long as a continuous response was ongoing throughout therapy
• NOTE: For example, a patient who started treatment with rituximab/bendamustine and was then switched to rituximab(R)-cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, and prednisone (CHOP) (due to insufficient response or excessive toxicity) would be counted as having received 2 regimens; however, R-CHOP alternating with R-dexamethasone, high-dose cytarabine, and cisplatin (DHAP) as a planned induction regimen would count as one regimen
• Patient does not have any documented history of central nervous system (CNS) involvement by mantle cell lymphoma; this includes no evidence of parenchymal brain, spinal cord, or cerebrospinal fluid involvement; radiculopathy symptoms from nerve root compression by lymphoma do not constitute CNS involvement
• Patient must have archived formalin-fixed paraffin-embedded (FFPE) tumor tissue specimen from the original diagnostic biopsy available for submission to Adaptive Biotechnologies for ClonoSEQ ID molecular marker identification of unique clonal immunoglobulin deoxyribonucleic acid (DNA) sequence
• NOTE: Patients for whom the molecular marker is identified will have peripheral blood collected after completion of induction (patient?s disease status is PR or CR) and submitted to Adaptive Biotechnologies for minimal residual disease (MRD) assessment
• INCLUSION CRITERIA FOR TREATMENT ASSIGNMENT (STEP 1)
• Patients must have met eligibility criteria for the screening step
• Institution has received results from Adaptive Biotechnologies as defined by one of the following criteria:
• Patients are ?MRD Indeterminate?: ClonoSEQ ID molecular marker assessment did not identify any unique clonal immunoglobulin DNA sequence OR
• ClonoSEQ ID molecular marker assessment identified unique clonal immunoglobulin DNA sequence and MRD assessment is completed
• Patients must have completed induction therapy within 120 days prior to preregistration to step 0, AND no more than 300 days may have elapsed from the first dose of induction chemotherapy (cycle 1 [C1] day 1 [D1]) given, until the last day of induction chemotherapy administered; for those assigned to Arms A, C, or D, the date of transplant (?day 0?) must not be greater than 365 days after the first dose of induction chemotherapy (C1D1) given
• Patient must have received at least four (4) cycles of induction therapy
• Up to two regimens of chemotherapy are allowed as long as a continuous response was ongoing throughout therapy
• NOTE: For example, a patient who started treatment with rituximab/bendamustine and was then switched to R-CHOP (due to insufficient response or excessive toxicity) would be counted as having received 2 regimens; however, R-CHOP alternating with R-DHAP as a planned induction regimen would count as one regimen
• Patients must have achieved a radiologic complete or partial remission as defined by the Lugano criteria
• Patients must meet institutional eligibility requirements for stem cell transplant, including cardiac, renal, liver, and pulmonary requirements
• Patients have an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2
• Human immunodeficiency virus (HIV) positive patients are not excluded, but to enroll, must meet all of the below criteria:
• HIV is sensitive to antiretroviral therapy
• Must be willing to take effective antiretroviral therapy if indicated
• CD4 count at screening >= 300 cells/mm^3
• No history of acquired immune deficiency syndrome (AIDS)-defining conditions
• Patient must be disease-free >= 3 years of prior malignancies with the exception of adequately treated non-melanoma skin cancer, adequately treated in situ carcinoma, low grade prostate carcinoma (Gleason grade =< 6) managed with observation that has been stable for at least 6 months
• Women must not be pregnant or breast-feeding
• All females of childbearing potential must have a blood test or urine study within 2 weeks prior to registration to rule out pregnancy
• A female of childbearing potential is any woman, regardless of sexual orientation or whether they have undergone tubal ligation, who meets the following criteria: 1) has not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been naturally postmenopausal for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months)
• Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study

Main Inclusion Criteria:

• Diagnosis of primary AML or AML with myelodysplasia-related changes (AML-MRC)
• Patient is in first or second relapse or has refractory disease. Patients must have had histologic verification of AML at the original diagnosis.
• Patient must be positive for the following FLT3 mutations in bone marrow or PB: FLT3 internal tandem duplication (ITD), FLT3 tyrosine kinase domain (TKD) D835 or I836 or FLT3-ITD and specified FLT3-TKD.
• ECOG performance status 0-2
• Life expectancy of at least 3 months in the opinion of the investigator.
• Normal hepatic and renal function.
• Patient is able to swallow oral medications.
• Female patients are postmenopausal, documented as surgically sterile, use two methods of contraception or practice true abstinence and have a negative urine pregnancy test at screening.
• Male patients even if surgically sterilized agree to practice true abstinence or use highly effective barrier contraception.

Main Exclusion Criteria:

• Diagnosis of acute promyelocytic leukemia.
• Known BCR-ABL-positive leukemia.
• AML secondary to prior chemotherapy for other neoplasms (except for MDS).
• AML that has relapsed after or is refractory to more than 2 lines of therapy.
• Clinically active central nervous system leukemia or prior history of NCI CTCAE Grade ≥ 3 drug-related CNS toxicity.
• Major surgery or radiation therapy within 4 weeks prior to the first study dose.
• Prior treatment with iadademstat or FLT3 inhibitors (except sorafenib or midostaurin used in first line as part of induction).
• Patients not eligible to receive gilteritinib per label.
• Prior treatment with 3 or more lines of AML therapy.
• Treatment with any investigational products within 3 weeks prior to first dose of study treatment.
• Uncontrolled hypertension or poorly controlled diabetes.
• Evidence of active uncontrolled viral, bacterial, or systemic fungal infection.
• Pregnant or lactating women.