A Study to Evaluate the Safety, Pharmacokinetics, and Activity of XmAb24306 in Combination With Cevostamab in Participants With Relapsed/Refractory Multiple Myeloma

Inclusion Criteria:

* Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
* Life expectancy of at least 12 weeks
* Participants must have received a minimum of 3 prior lines of therapy, including at least one PI, one IMiD, and an anti-CD38 monoclonal antibody.
* Documented evidence of progressive disease on or after the last prior therapy, or participants who were intolerant to the last prior therapy.
* Measurable disease, as defined by the protocol
* Participants agree to follow contraception or abstinence requirements as defined in the protocol

Exclusion Criteria:

* Any anti-cancer therapy within 3 weeks prior to initiation of study treatment with exception defined by the protocol
* Participants with autologous stem cell transplantation (SCT) within 100 days prior to first dose of study treatment
* Participants with prior allogeneic SCT or solid organ transplantation
* Known history of hemophagocytic lymphohistiocytosis (HLH) or macrophage activation syndrome (MAS)
* Active or history of autoimmune disease
* Participants with current or history of Central Nervous System (CNS) disease, or current CNS involvement by Multiple Myeloma (MM)
* Significant cardiovascular disease
* Participants with known clinically significant liver disease
* Symptomatic active pulmonary disease requiring supplemental oxygen
* Known active infection requiring intravenous anti-microbial therapy within 14 days prior to first study drug administration
* Any episode of active, symptomatic COVID-19 infection, or requiring treatment with IV antivirals for COVID-19 (not including COVID-19 primary prophylaxis) within 14 days, prior to first study treatment
* Other protocol defined inclusion/exclusion criteria may apply