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

This trial will look at a drug called SEA-CD70 with and without azacitidine, to find out if it is safe for participants with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). It will study SEA-CD70 to find out what its side effects are and if it works for AML and MDS. A side effect is anything the drug does besides treating cancer. This study will have seven groups or "parts." * Part A will find out how much SEA-CD70 should be given to participants * Part B will use the dose found in Part A to find out how safe SEA-CD70 is and if it works to treat participants with MDS. * Part C will use the dose found in Part A to find out how safe SEA-CD70 is and if it works to treat participants with AML. * Part D will find out how much SEA-CD70 with azacitidine should be given to participants * Part E will use the dose found in Part D to find out how safe SEA-CD70 with azacitidine is and if it works to treat participants with MDS or MDS/AML that has not been treated. * Part F will use the dose found in Part D to find out how safe SEA-CD70 with azacitidine is and if it works to treat participants with MDS or MDS/AML. * Part G will find out how much SEA-CD70 with azacitidine and with venetoclax should be given to participants with AML. Also, to evaluate safety and tolerability of PF-08046040 in combination with azacitidine and venetoclax in participants with previously untreated AML who are unfit for standard induction chemotherapy.

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 \