Phase 1b/2 Safety and Efficacy of APR-246 w/Azacitidine for tx of TP53 Mutant Myeloid Neoplasms

Participants will be treated for a total of 6 cycles. For participants responding or who have stable disease following cycle 6, treatment may continue until one of the following criteria applies: * Inter-current illness that prevents further administration of treatment, * Unacceptable adverse event(s), * Participant decides to withdraw from the study, or * General or specific changes in the participant's condition render the participant unacceptable for further treatment in the judgment of the investigator. * Evidence of disease progression by the International Working Group (IWG) 2006 criteria. Participants who wish not to continue treatment at time of disease assessment at end of cycle 6 will complete their end of treatment visit upon completion of cycle 6.