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:

1. Have documented CD20+ aggressive B-NHL, with disease that has progressed after at least 2 lines of systemic therapy containing an anti-CD20 antibody and an alkylating agent. 2. Measurable disease on cross sectional imaging as defined in the protocol 3. Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 4. Adequate bone marrow, renal and hepatic function as defined in the protocol 5. During dose expansion phase of the study, participant should be willing to undergo mandatory tumor biopsies, if in the opinion of the investigator, the participant has an accessible lesion that can be biopsied without significant risk to the participant.

Key Exclusion Criteria:

1. Prior treatments with allogeneic stem cell transplantation or solid organ transplantation, treatment with anti-CD20 x anti- CD3 bispecific antibody, such as odronextamab 2. Diagnosis of mantle cell lymphoma (MCL) 3. Primary central nervous system (CNS) lymphoma or known involvement by non-primary CNS lymphoma 4. Treatment with any systemic anti-lymphoma therapy within 5 half-lives or within 14 days prior to first administration of study drug, whichever is shorter 5. Standard radiotherapy within 14 days of first administration of study drug. 6. Continuous systemic corticosteroid treatment with more than 10 mg per day of prednisone or corticosteroid equivalent within 72 hours of start of odronextamab 7. Co-morbid conditions, as described in the protocol 8. Infections, as described in the protocol 9. Allergy/hypersensitivity: Known hypersensitivity to both allopurinol and rasburicase NOTE: Other protocol defined inclusion / exclusion criteria apply

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

Key Inclusion Criteria

• Participant must be greater than or equal to (>=) 18 years of age, at the time of signing informed consent
• All participants must have relapsed or refractory disease for each histologic subtype
• Mature aggressive large B cell NHL and Follicular Lymphoma Grade 3b: Participants must have >= 2 lines of systemic therapy or >=1 line of systemic therapy in case of participants ineligible for high-dose chemotherapy and autologous Hematopoietic stem cell transplantation (HSCT). Participants also must have had exposure to an anthracycline and an anti-CD20 targeted agent
• Follicular lymphoma Grade 1-3a and Marginal Zone Lymphoma: Participants must have >=2 prior lines of anti-neoplastic systemic therapy. Participants also must have prior exposure to an anti-CD20 monoclonal antibody
• Tumor must be cluster of differentiation (CD) 20 positive
• Measurable disease as defined by Lugano 2014 classification
• Eastern Cooperative Oncology Group (ECOG) performance status of either 0 or 1

Key Exclusion Criteria

• Diagnosis of Human herpes virus (HHV) 8-positive Diffuse large B Cell lymphoma (DLBCL)
• Prior allogeneic Hematopoietic stem cell transplantation (HSCT)
• Autologous stem cell transplant within 12 weeks of chimeric antigen receptor (CAR) T cell infusion
• Uncontrolled active infections
• History of deep vein thrombosis or pulmonary embolism within six months of infusion (except for line associated deep vein thrombosis [DVT])
• History of stroke, unstable angina, myocardial infarction, congestive heart failure ( New York Heart Association [NYHA] Class III or IV), severe cardiomyopathy or ventricular arrhythmia requiring medication or mechanical control within 6 months of screening
• History of a seizure disorder, cerebrovascular ischemia/hemorrhage, dementia, cerebellar disease or neurodegenerative disorder
• Known history or prior diagnosis of optic neuritis or other immunologic or inflammatory disease affecting the central nervous system
• Active central nervous system (CNS) involvement by malignancy
• Current active liver or biliary disease (except for Gilbert's syndrome or asymptomatic gallstones)

• Participant must be greater than or equal to (>=) 18 years of age, at the time of signing informed consent
• Diagnosis of mature aggressive large B cell non-Hodgkin lymphoma or follicular lymphoma
• Tumor must be histologically confirmed cluster of differentiation (CD)19 and/or CD20 positive
• Must have relapsed or refractory disease with the following indications for each histologic subtype: Mature aggressive large B cell non-Hodgkin lymphoma (NHL) and follicular lymphoma Grade 3b: Participants must have >= 2 lines of systemic therapy, or >= 1 line of systemic therapy for participants who are ineligible for autologous stem cell transplant; Follicular lymphoma Grade 1-3a and marginal zone lymphoma: Participants must have >= 2 prior lines of anti-neoplastic systemic therapy. Participants also must have prior exposure to an anti-CD20 monoclonal antibody
• Measurable disease as defined by Lugano 2014 classification
• Eastern cooperative oncology group (ECOG) performance status of either 0 or 1

Exclusion Criteria

• Diagnosis of Human herpes virus (HHV) 8-positive diffuse large B Cell lymphoma (DLBCL)
• Prior allogeneic hematopoietic stem cell transplantation (HSCT)
• Autologous stem cell transplant within 12 weeks of chimeric antigen receptor (CAR) T cell infusion
• Uncontrolled active infections
• History of deep vein thrombosis or pulmonary embolism within six months of infusion (except for line associated deep vein thrombosis [DVT])
• History of stroke, unstable angina, myocardial infarction, congestive heart failure New York Heart Association (NYHA) Class III or IV, severe cardiomyopathy or ventricular arrhythmia requiring medication or mechanical control within 6 months of screening
• History of a seizure disorder, cerebrovascular ischemia/hemorrhage, dementia, cerebellar disease or neurodegenerative disorder
• Known history or prior diagnosis of optic neuritis or other immunologic or inflammatory disease affecting the central nervous system
• Current active liver or biliary disease (except for Gilbert's syndrome or asymptomatic gallstones)

Inclusion Criteria:

• Patients must be >= 1 year and < 22 years of age at the time of enrollment
• Patients must have B-ALL, or previously diagnosed B lymphoblastic lymphoma (B-LL), with >= 5% (M2 or M3) bone marrow blasts with or without extramedullary disease
• NOTE: Relapsed patients previously diagnosed with B-lymphoblastic lymphoma (B-LL) are eligible if they have an M2 or M3 marrow at the time of enrollment on this study
• Patients with ALL or B-LL who have M2 morphology must have local confirmatory testing showing >= 5% blasts by flow cytometry, fluorescence in situ hybridization (FISH) testing or other molecular method
• Leukemic blasts must demonstrate surface expression of CD22 at the time of relapse by local/institutional flow cytometry of a bone marrow aspirate sample; (assessment of CD22 using a bright fluorophore such as phycoerythrin [PE] is strongly recommended)
• In the case of an inadequate aspirate sample (dry tap) or if bone marrow aspirate is unable to be performed due to patient clinical status, flow cytometry of peripheral blood specimen may be substituted if the patient has at least 1,000/uL circulating blasts; alternatively, CD22 expression may be documented by immunohistochemistry of a bone marrow biopsy specimen
• Patients with one of the following:
• Second or greater relapse;
• Primary refractory disease with at least 2 prior induction attempts;
• First relapse refractory to at least one prior re-induction attempt
• Any relapse after HSCT (Cohort 1 ONLY) Patients with Down syndrome are eligible ONLY for Cohort 1 with:
• Any of above disease status, OR
• First relapse with no prior re-induction attempt NOTE: Patients with Down syndrome or prior HSCT are NOT eligible for Cohort 2 combination therapy
• Patients with Philadelphia chromosome (Ph)+ ALL must have had two prior therapy attempts including two different tyrosine kinase inhibitors (TKIs)
• Patients must have fully recovered from the acute toxic effects of all prior anti-cancer therapy, defined as resolution of all such toxicities to =< grade 2 or lower per the inclusion/exclusion criteria prior to entering this study. Apply to Cohort 2:
• Cytotoxic chemotherapy or other anti-cancer agents known to be myelosuppressive. For agents not listed, the duration of this interval must be discussed with the study chair and the study-assigned Research Coordinator prior to enrollment.
• A waiting period prior to enrollment is not required for patients receiving standard cytotoxic maintenance chemotherapy (i.e., corticosteroid, vincristine, 6MP, and/or methotrexate).
• A waiting period is not required for patients receiving a single dose of intrathecal methotrexate, hydrocortisone, and/or cytarabine within 7 days prior to enrollment
• >= 14 days must have elapsed after the completion of other cytotoxic therapy, with the exception of hydroxyurea, for patients not receiving standard maintenance therapy. For patients who previously received calaspargase pegol, >= 21 days must have elapsed after the last dose. Additionally, patients must have fully recovered from all acute toxic effects of prior therapy.
• Note: Cytoreduction with hydroxyurea must be discontinued >= 24 hours prior to the start of protocol therapy.
• Anti-cancer agents not known to be myelosuppressive (e.g., not associated with reduced platelet or absolute neutrophil count [ANC] counts): >= 7 days after the last dose of agent. For agents not listed, the duration of this interval must be discussed with the study chair and the study-assigned research coordinator prior to enrollment.
• Anti-cancer agents that are antibodies: >= 21 days must have elapsed from infusion of last dose of antibody, and toxicity related to prior antibody therapy must be recovered to grade =< 1. There is an exception for blinatumomab infusions, for which patients must have been off for at least 3 days and all drug related toxicity must have resolved to grade 2 or lower as outlined in the inclusion/exclusion criteria.
• Corticosteroids: If used to modify immune adverse events related to prior therapy, >= 14 days must have elapsed since last dose of corticosteroid. A waiting period prior to enrollment is not required for patients receiving corticosteroid for leukemia therapy/cytoreduction.
• Radiotherapy: >= 2 weeks must have elapsed since local palliative radiation therapy (XRT) (small port); >= 3 months must have elapsed if prior cranial or craniospinal XRT was received, if >= 50% of the pelvis was irradiated, or if total body irradiation (TBI) was received; >= 6 weeks must have elapsed if other substantial bone marrow irradiation was given.
• Stem cell transplant or rescue without TBI: For Cohort 1, at least 90 days must have elapsed since stem cell transplant and at least 30 days from donor lymphocyte infusion. Patient must have had no more than one previous HSCT and currently have no evidence of active graft vs. host disease (GVHD). For Cohort 2, no prior HSCT is allowed.
• Chimeric antigen receptor (CAR) T cell therapy: At least 30 days must have elapsed from the last CAR-T cell infusion
• Patients must have a performance status corresponding to Eastern Cooperative Oncology Group (ECOG) scores of 0, 1, or 2; use Karnofsky for patients > 16 years of age and Lansky for patients =< 16 years of age; patients who are unable to walk because of paralysis, but who are up in a wheelchair, will be considered ambulatory for the purpose of assessing the performance score
• Creatinine clearance or radioisotope glomerular filtration rate (GFR) >= 70 mL/min/1.73 m^2 or
• A serum creatinine 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)
• Direct bilirubin =< 1.5 x upper limit of normal (ULN) for age, and
• Serum glutamic pyruvic transaminase (SGPT) (alanine aminotransferase [ALT]) =< 5 x ULN for age; for the purpose of this study, the ULN for ALT will be 45 U/L

Exclusion Criteria:

• Patients with any prior history of SOS irrespective of severity
• Patients with isolated central nervous system (CNS), testicular, or any other extramedullary site of relapse
• Patients who have been previously treated with inotuzumab ozogamicin
• Patients who have previously received HSCT (Cohort 2 only)
• Patients with Down syndrome (Cohort 2 only)
• History of allergic reaction attributed to compounds of similar or biologic composition to inotuzumab ozogamicin or other agents in the study
• Note: Patients with history of allergy to pegaspargase/calaspargase pegol are eligible for enrollment on Cohort 2 if Erwinia formulation of asparaginase can be obtained
• Patients with active optic nerve and/or retinal involvement are not eligible; patients who are presenting with visual disturbances should have an ophthalmologic exam and, if indicated, a magnetic resonance imaging (MRI) to assess optic nerve or retinal involvement
• Patients who are currently receiving another investigational drug
• Patients who are currently receiving or plan to receive other anti-cancer agents (except hydroxyurea, which may be continued until 24 hours prior to start of protocol therapy, and intrathecal chemotherapy)
• 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 or anti-rejection medications
• Patients who are currently receiving or plan to receive corticosteroids except as described below
• Systemic corticosteroids may be administered for cytoreduction up to 24 hours prior to the start of protocol therapy, (Cohort 1 only) for all patients, corticosteroids may be administered as a premedication for inotuzumab ozogamicin and as treatment for allergic reactions or for physiologic replacement/stress dosing of hydrocortisone for documented adrenal insufficiency; corticosteroids are not allowed for other indications
• Patients with known human immunodeficiency virus (HIV), hepatitis B or C infections; testing to prove negative status is not required for enrollment unless it is deemed necessary for usual medical care of the patient
• Patients who have an active uncontrolled infection defined as:
• Positive bacterial blood culture within 48 hours of study enrollment;
• Fever above 38.2 degree Celsius (C) 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 of study enrollment or active therapy for presumed invasive fungal infection
• Patients may be receiving IV or oral antibiotics to complete a course of therapy for a prior documented infection as long as cultures have been negative for at least 48 hours and signs or symptoms of active infection have resolved; for patients with clostridium (C.) difficile diarrhea, at least 72 hours of antibacterial therapy must have elapsed and stools must have normalized to baseline
• Active viral or protozoal infection requiring IV treatment
• Patients known to have one of the following concomitant genetic syndromes: Bloom syndrome, ataxia-telangiectasia, Fanconi anemia, Kostmann syndrome, Schwachman (Schwachman-Diamond-Blackfan) syndrome or any other known bone marrow failure syndrome
• There have been no human studies of inotuzumab ozogamicin in pregnant women and no reports of exposure in utero; based on nonclinical safety studies, inotuzumab ozogamicin has the potential to impair human male and female fertility and to adversely affect human embryo fetal development; women of childbearing potential should be advised to avoid becoming pregnant while receiving inotuzumab ozogamicin; there is no information regarding the presence of inotuzumab ozogamicin in human milk, the effects on the breast-fed infant, or the effects on milk production; because of the potential for adverse reactions in breast-fed infants, women should not breast-feed during treatment with inotuzumab ozogamicin and for at least 2 months after the final dose
• Female patients of childbearing potential are not eligible unless a negative pregnancy test result has been obtained within 7 days prior to enrollment
• Female patients who are sexually active and of reproductive potential are not eligible unless they agree to use an effective contraceptive method for the duration of their study participation and for 8 months after the last dose of inotuzumab ozogamicin
• Men with female partners of childbearing potential should use effective contraception during treatment with inotuzumab ozogamicin and for at least 5 months after the last dose of inotuzumab ozogamicin
• Lactating females are not eligible unless they agree not to breastfeed their infants

Inclusion Criteria:

1. Ability to understand and the willingness to sign a written informed consent document and to comply with the study protocol procedures. 2. Age ≥18 years at the time of signing informed consent. Because no dosing or adverse event data are currently available on the use of mosunetuzumab in patients <18 years of age, they are excluded from this study. 3. Histologically confirmed diagnosis of:
• follicular lymphoma (grade 1, 2, 3a, or not otherwise specified) or
• marginal zone lymphoma (nodal, extranodal, or splenic), according to 2016 WHO classification and confirmed to express the CD20 antigen by immunohistochemistry or flow cytometry. Patients in whom definitive pathologic subtype of FL/MZL is undetermined due to limited biopsy material can be enrolled if in the investigator's opinion integrated clinicopathologic data are consistent with the eligible diagnosis. 4. Agreement to provide, if available, lymphoma tissue for correlative analyses. 5. At least one bi-dimensionally measurable nodal lesion, defined as >1.5 cm in its longest dimension, or one bi-dimensionally measurable extranodal lesion, defined as >1.0 cm in its longest diameter; with the exception of splenic MZL, which must be evaluable using the International SMZL Group criteria. 6. No prior systemic therapy for B-cell lymphoma, except for palliative corticosteroids; prior local therapy (surgery, radiation therapy, or antibiotics) is allowed. 7. Indication to start systemic therapy for lymphoma:
• Patients with FL must meet one of the GELF criteria:
• any mass ≥7 cm (except spleen);
• at least 3 nodes >3 cm in diameter;
• symptomatic spleen enlargement;
• local symptoms or compromise of normal organ function due to tumor mass;
• presence of ascites or pleural effusion;
• presence of B symptoms (fever, night sweats, or unintentional weight loss of >10% over ≤6 months);
• serum lactate dehydrogenase or beta-2-microglobulin above upper limit of normal;
• cytopenias due to underlying lymphoma (i.e., absolute neutrophil count <1.0 × 109/L, hemoglobin <10 g/dL, and/or platelet count <100 × 109/L).
• Patients with MZL must have an indication to start therapy as assessed by the investigator. 8. Performance status ECOG 0, 1, or 2. 9. Adequate hematologic function (unless due to underlying lymphoma as established by bone marrow involvement or splenomegaly):
• hemoglobin ≥9 g/dL,
• absolute neutrophil count ≥1.0 x 109/L,
• platelet count ≥75 x 109/L. 10. Glomerular filtration rate (GFR) ≥40 mL/min/1.73m2 using the Mayo Quadratic Formula. 11. The effects of mosunetuzumab on the developing human fetus are unknown. For this reason and because lenalidomide used in this trial is known to be teratogenic, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) and refrain from donating eggs or sperm throughout the treatment and for 3 months after the last dose of trial therapy. 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. 12. Agreement to enroll in and comply with all local requirements of the REVLIMID® (lenalidomide) Risk Evaluation and Mitigation Strategy (REMS®) program for the purpose of lenalidomide acquisition.

Exclusion Criteria:

1. Grade 3b follicular lymphoma or transformed lymphoma. 2. Prior treatment with any anti-CD20 antibody or lenalidomide for lymphoma. 3. Prior stem cell transplantation (autologous or allogeneic) or prior solid organ transplantation. 4. History of severe allergic or anaphylactic reactions to humanized or murine monoclonal antibodies or known sensitivity or allergy to murine products. 5. Known NYHA class 3/4 congestive heart failure, LVEF <40%, myocardial infarction within 6 months prior to enrollment, unstable angina, or unstable arrhythmia. 6. Chronic obstructive pulmonary disease (COPD) requiring oral corticosteroids or chronic oxygen. 7. History of autoimmune disease, including, but not limited to myasthenia gravis, myositis, autoimmune hepatitis, idiopathic pulmonary fibrosis, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, antiphospholipid syndrome, granulomatosis with polyangiitis, Guillain-Barré syndrome, multiple sclerosis, vasculitis, or glomerulonephritis, with the exception of: hypothyroidism (on stable dose of thyroid replacement therapy), asthma managed with inhaled medications only; type 1 diabetes mellitus on stable insulin regimen, Sjögren syndrome, immune thrombocytopenia or autoimmune hemolytic anemia that does not require systemic therapy; dermatologic condition (including eczema, psoriasis, lichen simplex chronicus, or vitiligo) with skin manifestations with rash covering <10% of body surface area and not requiring treatment other than low-potency topical corticosteroids for >12 months prior to registration. 8. Use of any systemic immunosuppressive medications (including, but not limited to, cyclophosphamide, azathioprine, methotrexate, thalidomide, and anti-tumor necrosis factor agents) with the exception of corticosteroid treatment using <10 mg/day prednisone or equivalent within 2 weeks prior to first treatment; a brief course of palliative corticosteroids at higher doses (prednisone up to 100 mg daily, for up to 7 days) is allowed, but must be completed at least 7 days before the first dose of mosunetuzumab. 9. Any of the following conditions:
• active bacterial infection requiring antibiotics
• known or suspected chronic active Epstein Barr virus (CAEBV) infection
• history of hemophagocytic lymphohistiocytosis (HLH)
• confirmed progressive multifocal leukoencephalopathy (PML)
• known active EBV or CMV viremia
• positive test for hepatitis B surface antigen (HBSAg). Patients with a positive total/IgG hepatitis B core antibody (HBcAb) may participate if hepatitis B virus (HBV) DNA is undetectable at screening, if they agree to take entecavir or tenofovir, and undergo periodic DNA testing
• positive hepatitis C virus (HCV) antibody, unless a negative polymerase chain reaction (PCR) for HCV is documented
• positive test for HIV. 10. Administration of a live, attenuated vaccine within 4 weeks before first mosunetuzumab dose or anticipation that such a live, attenuated vaccine will be required during the study. 11. Current or past history of CNS disease, including stroke, epilepsy, or CNS vasculitis, or an advanced neurodegenerative disease; with the exception of: stroke >2 years before registration without any residual neurologic deficits and no subsequent transient ischemic attacks; history of epilepsy with no seizures for >2 years and not using any antiepileptic therapy; well-controlled Parkinson's disease (with no need for a significant medication adjustment for > 6 months). 12. History of other malignancy that could affect compliance with the protocol or interpretation of results; patients with a curatively treated skin cancer, in situ cervical cancer, or another malignancy treated curatively with a documented remission >2 years before registration are eligible. 13. Known active bacterial, viral, fungal, mycobacterial, parasitic, or other infection (excluding fungal infections of nail beds) at study enrollment or any major episode of infection requiring treatment with IV antibiotics or hospitalization within 4 weeks before the first dose of mosunetuzumab. 14. Clinically significant liver disease, including viral or other hepatitis, current alcohol abuse, or cirrhosis. 15. Any major surgery within 4 weeks before the first dose of mosunetuzumab, other than lymph node biopsy for diagnosis. 16. Evidence of other significant or uncontrolled medical or psychiatric conditions that could affect compliance with the protocol. 17. Any of the following abnormal laboratory values within 14 days prior to first dose of mosunetuzumab:
• AST or ALT >3x ULN
• total bilirubin >2 x ULN (unless due to Gilbert syndrome with indirect hyperbilirubinemia only)
• INR>1.5 x ULN without anticoagulation
• PTT or APTT >1.5x ULN in the absence of lupus anticoagulant. 18. Any radiation therapy within 2 weeks prior to first dose of mosunetuzumab. 19. Pregnancy, breast-feeding, or prisoner status. Women of childbearing potential must have a negative pregnancy test within 2 weeks before first dose of mosunetuzumab, and must undergo repeat pregnancy testing during each cycle of lenalidomide therapy (see Inclusion Criterion 11).

Inclusion Criteria:

• Patients must be 1 month to < 6 years old at the time of study enrollment and must have had initial diagnosis of leukemia at < 2 years old.
• Patients must have KMT2A-rearranged acute lymphoblastic leukemia (ALL), acute leukemia of ambiguous lineage (ALAL), or mixed phenotype acute leukemia (MPAL), which is determined to be refractory or in first marrow relapse. All patients must undergo cytogenetics and fluorescence in situ hybridization (FISH) testing of a relapsed/refractory blast sample at a Children's Oncology Group (COG)-approved laboratory for KMT2A-R status determination and the presence of a KMT2A- rearrangement must be confirmed by central review. Cytogenetics results must be submitted for central review by Day 10 of protocol therapy, for confirmation of KMT2A-R status. Patients enrolled with refractory disease may utilize initial diagnostic cytogenetics for eligibility and submission for central review if testing was performed at a COG approved laboratory. Patients will be eligible to remain on protocol therapy if KMT2A-R is confirmed by central review. Additional methods of assessing for KMT2A-R may be considered if FISH does not detect the rearrangement.
• Disease status at time of enrollment must be one of the following:
• First relapse: Any recurrence of marrow disease, with or without other extramedullary sites(s), at any point after achieving remission. ("Remission-1", per definition below) meeting one of these criteria:
• Relapse M1: M1 morphology (< 5% blasts) + at least 2 confirmatory tests showing >= 1% blasts (testing includes flow, cytogenetics, polymerase chain reaction [PCR]ext-generation sequencing [NGS] of immunoglobulin [Ig]/T-cell receptor [TCR] rearrangement, and/or PCR or NGS of fusion gene identical to diagnosis), OR
• Relapse M2: M2 morphology (5-25% blasts) + 1 confirmatory test showing > 1% blasts, OR
• Relapse M3: M3 morphology (> 25% blasts)
• Refractory, or failure to achieve Remission-1: Remission-1 is defined as < 1% marrow blasts by flow minimal residual disease (MRD) and resolution of extramedullary disease by the end of Consolidation, or 2 courses of frontline chemotherapy.
• Central Nervous System (CNS) disease: Patients must have CNS1 or CNS2 status and no clinical signs or neurologic symptoms suggestive of CNS leukemia, such as cranial palsy.
• Patients with CNS3 disease may receive antecedent intrathecal chemotherapy to achieve CNS1 or CNS2 status prior to enrollment.
• Patients with a history of CNS chloromatous disease are required to have no radiographic evidence of CNS disease prior to enrollment.
• White blood cell (WBC) must be < 50,000/uL at the time of study enrollment. Patients can receive cytoreduction with hydroxyurea and/or corticosteroids for up to 7 days prior to enrollment.
• Patients >= 12 months of age must have a performance status by Lansky Scale of >= 50%.
• Patients must be able to take enteral medications. Acceptable routes of administration for SNDX-5613 include: oral (PO), nasogastric (NG) tube, nasojejunal (NJ) tube, nasoduodenal (ND), and gastrostomy tube (G-tube).
• Patients must have fully recovered from the acute toxic effects of all prior chemotherapy, immunotherapy, or radiotherapy prior to entering this study
• Cytotoxic chemotherapy or other anti-cancer agents known to be myelosuppressive:
• >= 14 days must have elapsed after the completion of other cytotoxic therapy, including patients who relapse during pre-Maintenance upfront therapy, with these specific exceptions: cytoreduction with hydroxyurea and/or corticosteroids, and intrathecal chemotherapy, which have no required washout periods. For patients who relapse during upfront Maintenance therapy, >= 7 days must have elapsed after the last dose of chemotherapy. Additionally, patients must have fully recovered from all acute toxic effects of prior therapy.
• NOTE: Cytoreduction with hydroxyurea and/or corticosteroids is permitted prior to enrollment for patients with WBC >= 50,000/uL, and by provider discretion regardless of WBC, to reduce potential risk of differentiation syndrome with SNDX-5613 initiation. Hydroxyurea and/or corticosteroids may be given for up to 7 days, with no wash-out required.
• NOTE: No waiting period is required for patients having received intrathecal cytarabine, methotrexate, and/or hydrocortisone. Intrathecal chemotherapy that is given up to 7 days prior to the initiation of protocol therapy counts as protocol therapy and not prior anti-cancer therapy. Intrathecal chemotherapy given > 7 days prior does not count as protocol therapy.
• NOTE: Prior exposure to fludarabine and cytarabine (FLA) is permitted.
• Anti-cancer agents not known to be myelosuppressive (e.g., not associated with reduced platelet or absolute neutrophil count [ANC] counts): >= 7 days after the last dose of agent.
• Antibodies: >= 21 days must have elapsed from infusion of last dose of antibody, and toxicity related to prior antibody therapy must be recovered to grade =< 1. There is an exception for blinatumomab infusions, for which patients must have been off for at least 3 days and all drug related toxicity must have resolved to grade 2 or lower as outlined in the inclusion/exclusion criteria.
• Hematopoietic growth factors: >= 14 days after the last dose of a long-acting growth factor (e.g., pegfilgrastim) or >= 7 days for short-acting growth factor. 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 and the study-assigned Research Coordinator.
• Interleukins, Interferons and Cytokines (other than hematopoietic growth factors): >= 21 days after the completion of interleukins, interferon, or cytokines
• Stem cell infusions (with or without total body irradiation (TBI):
• Allogeneic (non-autologous) bone marrow or stem cell transplant, or stem cell boost: >= 84 days after infusion
• Donor leukocyte infusion: >= 28 days
• Cellular Therapy: >= 28 days after the completion of any type of cellular therapy (e.g., modified T cells, natural killer [NK] cells, dendritic cells, etc.)
• Radiation Therapy (XRT)/External Beam Irradiation including protons: >= 14 days after local XRT; >= 84 days after TBI, craniospinal XRT or if radiation to >= 50% of the pelvis; >= 42 days if other substantial bone marrow radiation.
• A serum creatinine based on age as follows:
• Age 1 month to < 6 months: maximum serum creatinine 0.4 mg/dL
• Age 6 months to < 1 year: maximum serum creatinine 0.5 mg/dL
• Age 1 to < 2 years: maximum serum creatinine 0.6 mg/dL
• Age 2 to < 6 years: maximum serum creatinine 0.8 mg/dL OR
• a 24-hour urine Creatinine clearance >= 70 mL/min/1.73 m^2 OR
• a glomerular filtration rate (GFR) >= 70 mL/min/1.73 m^2. 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 creatinine, cystatin C or other estimates are not acceptable for determining eligibility.
• A direct bilirubin =< 1.5 x upper limit of normal (ULN) for age, unless disease related
• Serum glutamic-pyruvic transaminase (SGPT) (alanine aminotransferase [ALT]) =< 135 U/L (3 x ULN) unless disease related.
• Note: For the purpose of eligibility, the ULN for SGPT (ALT) has been set to the value of 45 U/L
• Shortening fraction of >= 27% by echocardiogram, or ejection fraction of >= 50% by radionuclide angiogram.
• Corrected QT interval using Fridericia formula (QTcF) of < 450 msec (using the average of triplicate measurements)
• NOTE: There are no specific electrolyte parameters for eligibility. However, it should be noted that, to limit QTc prolongation risk, patients must maintain adequate potassium and magnesium levels to initiate and continue SNDX-5613 on protocol therapy.
• Patients must be able to comply with the safety monitoring requirements of the study, in the opinion of the treating investigator.

Exclusion Criteria:

• Patients with isolated extramedullary leukemia.
• Patients diagnosed with Down syndrome.
• Patients known to have one of the following syndromes:
• Bloom syndrome, ataxia-telangiectasia, Fanconi anemia, Kostmann syndrome, Shwachman syndrome, or any other known bone marrow failure syndrome.
• Patients with a secondary KMT2A-R leukemia that developed after treatment of prior malignancy with cytotoxic chemotherapy.
• Patients with a history of congenital prolonged QT syndrome, congestive heart failure or uncontrolled arrhythmia in the past 6 months prior to study enrollment.
• Patients with an active, uncontrolled infection, further defined below:
• Positive bacterial blood culture within 48 hours of study enrollment
• Fever above 38.2 degrees Celsius (C) 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 of study enrollment or active therapy for presumed invasive fungal infection
• Patients may be receiving IV or oral antibiotics to complete a course of therapy for a prior documented infection as long as cultures have been negative for at least 48 hours and signs or symptoms of active infection have resolved. For patients with Clostridium (C.) difficile diarrhea, at least 72 hours of antibacterial therapy must have elapsed and stools must have normalized to baseline
• Active viral or protozoal infection requiring IV treatment
• Human immunodeficiency virus (HIV)-infected patients are eligible if on effective anti-retroviral therapy that does not interact with planned study agents and with undetectable viral load within 6 months of enrollment.
• Patients with active acute graft-versus-host disease (GVHD) > grade 0 (unless skin only), or chronic GVHD > mild (unless skin only) are not eligible. Patients with acute or chronic skin GVHD that is =< grade 1, or chronic skin GVHD that is graded as mild are eligible.
• Patients who have received a prior solid organ transplantation.
• Patients with known Charcot-Marie-Tooth disease, if treating on Regimen A (with vincristine).
• CYP3A4 Inhibitors or Inducers: Patients who require concomitant therapy with moderate or strong CYP3A4 inhibitors or inducers, as these are prohibited during the chemotherapy combination cycles. These agents should be discontinued at least 5 half-lives prior to starting protocol therapy. Concomitant use of strong CYP3A4 inhibitor -azole antifungals are permitted during the SNDX-5613 monotherapy cycles, with appropriate SNDX-5613 dose modification.
• P-glycoprotein (P-gp) inhibitors or inducers: Vincristine is a substrate for P-gp. Concomitant use of P-gp inhibitors or inducers with vincristine (patients receiving Regimen A Cycle 1) should be avoided.
• Investigational Drugs: Patients who are currently receiving another investigational drug.
• Anti-cancer Agents: Patients who are currently receiving other anti-cancer agents (exceptions: hydroxyurea and corticosteroids, which may be used as cytoreduction prior to enrollment).
• Anti-GVHD Agents: Patients who are receiving cyclosporine, tacrolimus, or other systemic agents to treat graft-versus-host disease post bone marrow transplant. Patients should discontinue anti-GVHD agents > 7 days prior to enrollment and have no evidence of worsening GVHD. Topical steroids are permitted.
• Patients who have previously been treated with SNDX-5613. Prior exposure to other menin inhibitors is permitted.
• 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:

• Has histologically confirmed diagnosis of classical Hodgkin lymphoma (cHL) that is 2-fluorodeoxyglucose-avid (FDG-avid).
• Has relapsed (defined as disease progression after most recent therapy) or refractory (defined as failed to achieve CR or PR to most recent therapy) cHL and exhausted all available treatment options with known clinical benefit.
• Has progressed on treatment with an anti-PD-(L)1 monoclonal antibody (mAb) administered either as monotherapy or in combination with other checkpoint inhibitors or other therapies.
• Submits an archival (<5 years) or newly obtained tumor tissue sample which has not been previously irradiated.

Exclusion Criteria:

• Diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy or any other form of immunosuppressive therapy.
• History of central nervous system (CNS) metastases or active CNS involvement.
• Has an active autoimmune disease that has required systemic treatment in past 2 years except replacement therapy.
• History of (noninfectious) pneumonitis/interstitial lung disease that required steroids or has current pneumonitis/interstitial lung disease.
• Has an active infection requiring systemic treatment.
• History of hemophagocytic lymphohisticytosis.
• Has an active seizure disorder that is not well controlled.
• Has clinically significant (ie, active) cardiovascular disease.
• Received prior systemic anticancer therapy including investigational agents within 4 weeks before randomization.
• Received prior radiotherapy within 2 weeks of start of study intervention or radiation related toxicities requiring corticosteroids.
• Has not adequately recovered from major surgical procedure.
• Known additional malignancy that is progressing or has required active treatment within the past 3 years.
• History of human immunodeficiency virus (HIV).
• Has had an allogeneic hematopoietic stem cell or solid organ transplantation within the last 5 years.

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
• Relapsed or refractory disease as defined by: i) Relapsed disease is defined as an initial response to prior treatment, followed by confirmed progressive disease by IMWG criteria greater than (>) 60 days after cessation of treatment; ii) Refractory disease is defined as less than (<) 25 percent (%) reduction in monoclonal paraprotein (M-protein) or confirmed progressive disease by IMWG criteria during previous treatment or less than or equal to (<=) 60 days after cessation of treatment
• 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)
• Received prior pomalidomide therapy
• 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