A Clinical Trial to Learn About the Study Medicine Called Maplirpacept (PF-07901801), Alone and When Used in Combination With Other Medicines to Treat Participants With Advanced Hematological Malignancies, Including Lymphoma, Leukemia and Multiple Myeloma

The purpose of this clinical trial is to learn how the experimental medicine maplirpacept (PF-07901801) affects people with various types of blood cancers: * relapsed or refractory (R/R) lymphoma * multiple myeloma * newly diagnosed acute myeloid leukemia (AML). This trial will be conducted in the outpatient setting in 2 parts, phase 1a and phase 1b. You may only participate in one part of the study. During phase 1a of this study, we will explore how much maplirpacept (PF-07901801), when used by itself, can be safely used. If you have lymphoma, the study medicine maplirpacept (PF-07901801) will be given by infusion through a vein once a week or once every 2 weeks or every 3 weeks as determined by your doctor. Following your first dose, you will be expected to come back twice more the first week. From week 2, you will have weekly visits for blood tests, questions about your medications, any side effects, or illnesses you may have experienced and your cancer response. After you have completed 21 days (for every week dosing) or 42 days (for every 2- or 3-weeks dosing), your doctor will discuss whether you should stop study treatment or continue. If you continue, you will be expected to come back weekly for blood tests, vital signs, a brief physical exam, asked about any side effects or illnesses you may have experienced and medications you may be taking. The dosing schedule you are assigned to will continue until your disease has worsened, significant side effects occur or other reasons that lead you and your doctor to decide treatment may be stopped. To be eligible for the first part of the study you must be 18 years or older, your disease has worsened after receiving other medicines approved for blood cancer, no other treatment options exist for you, a sample of your tissue for exploratory research which can be taken from tissue already obtained or if necessary, a new sample of your tissue will be taken so your disease may be seen and measured on routine tests/