A Safety Study of SEA-CD70 in Patients With Myeloid Malignancies

Part A Inclusion Criteria * Participants with cytologically/histologically confirmed MDS (2016 World Health Organization (WHO) classification) with * Measurable disease per WHO MDS with excess blasts criteria * MDS that is relapsed or refractory and must not have other therapeutic options * Treatment failure after prior hypomethylating agent (HMA) therapy for MDS * Eastern Cooperative Oncology Group (ECOG) performance status of 0-1 Part B Inclusion Criteria * Participants with cytologically/histologically confirmed MDS (WHO classification) with: * Measurable disease per WHO MDS with excess blasts (MDS-EB) criteria * MDS that is relapsed or refractory and must not have other therapeutic options * Treatment failure after prior HMA therapy for MDS * ECOG Performance Status of 0-2 Part C Inclusion Criteria * Participants with relapsed or refractory AML (ICC 2022) (except for acute promyelocytic leukemia \[APL\]): * Who have received either 2 or 3 previous regimens * Who have received 1 previous regimen to treat active disease and have at least one of the following: * Age \> 60 and ≤75 years. * Primary resistant AML or secondary AML * First CR duration \<6 months * Adverse-risk per European Leukemia Network genetic risk stratification * Age 18-75 years * ECOG performance status of 0-2 Parts D and F Inclusion Criteria * Participants with diagnosis of MDS or MDS/AML (ICC 2022 criteria) * Disease which has relapsed, failed to respond after minimum of 6 cycles, or progressed following an HMA in the immediately preceding line of therapy. * Eligible for continued therapy with azacitidine * ECOG Performance Status 0-2 Parts D and E Inclusion Criteria * Participants with diagnosis of MDS or MDS/AML (ICC 2022 criteria), previously untreated. * Participants with higher-risk per IPSS-M MDS and MDS/AML * ECOG Performance Status 0-2 Part G Inclusion Criteria * Participants with diagnosis of AML (ICC 2022 criteria), previously untreated and ineligible for standard induction chemotherapy. * Age ≥18 years. * ECOG Performance Status of 0-2. Exclusion Criteria (All Parts) * Previous exposure to CD70-targeted agents * Prior allogeneic hematopoietic stem cell transplant, for any condition * Central nervous system leukemia * History of clinically significant sickle cell anemia, autoimmune hemolytic anemia, or idiopathic thrombocytopenic purpura * Parts D, F and G only: Prior oral HMA or oral HMA-combinations * Part G: conditions that preclude enteral route of administration; concomitant use of strong/moderate CYP3A inducers; history of myeloproliferative neoplasm