The study will consists of two parts: a Part 1 dose escalation phase and a Part 2a expansion phase for safety, tolerability, PK, PD, and clinical activity testing. The study will enroll subjects with relapsed/refractory MM or other plasma cell disorders expressing BCMA. An adaptive 2-parameter Bayesian logistic regression model (BLRM) for dose-escalation with overdose control will be used in the dose-escalation phase for determination of the MTD or the RP2D. Dose-expansion phase of the study aims to collect preliminary evidence of antitumor activity and to confirm the safety of the HDP-101 as a monotherapy.
