The purpose of this study is to determine the recommended Phase 2 dose(s) (RP2D\[s\]) of bleximenib in phase 1 Part 1 (Dose Escalation) and to determine the safety and tolerability at RP2D in Phase 1 Part 2 (Dose expansion). The purpose of the Phase 2 part of the study is to evaluate the efficacy of bleximenib at the RP2D.