A Study Evaluating the Efficacy and Safety of Cevostamab in Prior B Cell Maturation Antigen (BCMA)-Exposed Participants With Relapsed/Refractory Multiple Myeloma

Inclusion Criteria: * Documented diagnosis of MM based on standard International Myeloma Working Group (IMWG) criteria * Evidence of progressive disease based on investigators determination of response by IMWG criteria on or after their last dosing regimen * Prior BCMA ADC or CAR-T Cohort: participants who have received a BCMA-targeted CAR-T or ADC therapy and are triple-class relapsed or refractory * Prior BCMA Bispecific Cohort: participants who have received a BCMA-targeting T-cell-dependent bispecific (TDB) antibody and are triple-class relapsed or refractory * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 * Life expectancy is at least 12 weeks * Agreement to protocol-specified assessments, including bone marrow biopsy and aspirate samples as detailed in the protocol * Resolution of AEs from prior anti-cancer therapy to Grade =\< 1 * For female participants of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraception during the treatment period and for at least 5 months after the final dose of cevostamab and for 3 months after the last dose of tocilizumab was administered * For male participants: agreement to remain abstinent (refrain from heterosexual intercourse) or use a condom, and agree to refrain from donating sperm during the treatment period and for at least 2 months after the final dose of tocilizumab (if applicable) to avoid exposing the embryo Exclusion Criteria: * Inability to…