S189: EARLY, DEEP, AND DURABLE RESPONSES, AND LOW RATES OF CRS WITH REGN5458, A BCMAXCD3 BISPECIFIC ANTIBODY, IN A PHASE 1/2 FIRST-IN-HUMAN STUDY IN PATIENTS WITH RELAPSED/REFRACTORY MULTIPLE MYELOMA. (23rd June 2022) - Zonder, J. A.