A Study to Investigate Safety and Efficacy With SAR445514 in Participants With Relapsed/Refractory Multiple Myeloma (RRMM) and Relapsed/Refractory Light-chain Amyloidosis (RRLCA)

This is a first-in-human (FIH) Phase 1/Phase 2 study for evaluating SAR445514 in monotherapy in participants with relapsed/refractory multiple myeloma (RRMM) and relapsed/refractory light chain amyloidosis (RRLCA). The study will comprise 3 parts: A dose escalation phase (Part 1) in RRMM participants (Part 1a) that will evaluate several doses administered to determine 2 doses that will be tested in the dose optimization part. A dose escalation will also be done in RRLCA participants (Part 1b) but started sequentially after the end of the dose escalation in RRMM participants. This dose escalation will evaluate the 2 doses planned to be used in dose optimization in RRMM, to ensure those doses are safe also for RRLCA participants. A dose optimization phase (Part 2) that will be evaluating 2 doses determined from Part 1 to determine the preliminary recommended Phase 2 dose (pRP2D) and schedule for SAR445514 in RRMM. A dose expansion phase (Part 3) that will evaluate the preliminary efficacy of pRP2D and schedule for SAR445514 in RRMM (Part 3a) and RRLCA (Part 3b). Approximately 111 participants will be enrolled and treated by study intervention and separated as such: Part 1a: Approximately 30 to 40 participants Part 1b: Approximately 6 to 12 participants Part 2: Approximately 30 participants Part 3a: Approximately 15 participants Part 3b: Approximately 14 participants