A Study to Investigate the Safety and Efficacy of SAR446523 Injected Subcutaneously in Adult Participants With Relapsed/Refractory Myeloma

This is a first-in-human study of SAR446523 conducted in patients with RRMM.

The study consists of two parts:

Dose escalation (Part A): In this part, up to 6 dose levels (DLs) of SAR446523 will be explored to determine the maximum administered dose (MAD), maximum tolerated dose (MTD), and recommended dose range (RDR) of 2 dose regimens which will be tested in the dose optimization part.

Dose optimization (Part B): In this part, participants will be randomly assigned in a 1:1 ratio using interactive response technology (IRT) to either one of the chosen dose regimens of SAR446523 (determined from data coming from Part A), to determine the optimal dose as the recommended phase 2 dose (RP2D) of SAR446523.

The study will be considered ongoing until the last participant last visit has occurred. Participants will be allowed to continue therapy until disease progression, unacceptable AEs, participant or Investigator's request to discontinue treatment.

Eligibility Criteria:
Inclusion Criteria:

* Participants with a documented diagnosis of multiple myeloma (MM) with measurable disease.
* Contraceptive use by men and women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.

Dose escalation (Part A)

* Participants must have received at least 3 prior lines of antimyeloma therapy, and must be either relapsed or refractory to the above therapies, or are intolerant to them.
* Note: In Part A, prior exposure to anti g-protein-coupled receptor, class c, group 5, member d (GPRC5D) therapy and anti B-cell maturation antigen (BCMA) therapy is allowed.

Dose optimization (Part B)

* Participants must have received at least 3 prior lines of antimyeloma therapy and be either relapsed or refractory to immunomodulator (IMiD), proteasome inhibitor (PI), anti CD38 monoclonal antibody (mAb), and anti BCMA targeting agent or are intolerant to them.
* Note: In Part B, prior exposure to antiGPRC5D therapy is not allowed.

Exclusion Criteria:

-Participants are excluded from the study if any of the following criteria apply: Eastern cooperative oncology group performance status (ECOG PS) of 2 or greater.

* Primary systemic and localized amyloid light chain (AL) amyloidosis, active polyneuropathy, organomegaly, endocrinopathy, myeloma protein, and skin changes (POEMS) syndrome, active plasma cell leukemia. Participants with central nervous system involvement or with clinical signs of meningeal involvement of multiple myeloma.
* Systemic antimyeloma treatment within 14 days before the first study treatment administration.
* Prior treatment with natural killer (NK)-cell engaging therapy (such as monoclonal antibody with antibody-dependent cellular cytotoxicity as primary mechanism of action) within 90 days of the first study treatment administration.
* Inadequate organ and marrow function.
* Participants with significant concomitant illness.

The above information is not intended to contain all considerations relevant to the potential participation in a clinical trial.