A Study Evaluating the Safety, Pharmacokinetics, and Activity of Cevostamab in Participants With Relapsed or Refractory Multiple Myeloma

Inclusion Criteria:

• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1

• Life expectancy of at least 12 weeks

• Agreement to provide bone marrow biopsy and aspirate samples

• Resolution of adverse events from prior anti-cancer therapy to Grade <=1

• Measurable disease

• For women of childbearing potential: agreement to remain abstinent or usecontraception, during the treatment period (including treatment interruptions) andfor at least 5 months after the last dose of cevostamab and at least 3 months afterthe last dose of tocilizumab was administered

• For men: agreement to remain abstinent or use a condom, and agreement to refrainfrom donating sperm, during the treatment period, and for at least 2 months afterthe last dose of tocilizumab was administered to avoid exposing the embryo andsexual partner Additional Arm A-Specific Inclusion Criteria

• Diagnosis of R/R MM for which no established therapy for MM is appropriate andavailable, or intolerance to those established therapies Additional Arm B-SpecificInclusion Criteria

• For Cohort B1S: Participants with R/R MM who have received at least two prior linesof treatment

• For Cohort B2S and additional cohorts: Participants with R/R MM who have received atleast 1 prior line of treatment

• Agreement to comply with all requirements of the pomalidomide pregnancy preventionprogram

• For women of childbearing potential: agreement to remain abstinent or use tworeliable methods of contraception starting at least 4 weeks prior to, during thetreatment period, and for at least 4 weeks after the last dose of pomalidomide wasadministered

• For men: agreement to remain abstinent or use a condom during the treatment periodand for at least 4 weeks after the last dose of pomalidomide, (even if he hasundergone a successful vasectomy) and agreement to refrain from donating sperm andblood during this same period Additional Arm C-Specific Inclusion Criteria

• For Cohort C1S: Participants with R/R MM who have received at least two prior linesof treatment

• For Cohort C2S and additional cohorts: Participants with R/R MM who have received atleast 1 prior line of therapy

• For women of childbearing potential: agreement to remain abstinent or usecontraceptive methods during the treatment period and for at least 102 days afterthe last dose of daratumumab was administered

• For men: agreement to remain abstinent or use a condom during the treatment periodand for at least 102 days after the last dose of daratumumab was administered toavoid exposing the embryo, and agreement to refrain from donating sperm during thissame period

Exclusion Criteria:

• Prior treatment with cevostamab or another agent targeting FcRH5

• Inability to comply with protocol-mandated hospitalization and activitiesrestrictions

• Pregnant or breastfeeding, or intending to become pregnant during the study orwithin 5 months after the last dose of cevostamab or within 3 months after the lastdose of tocilizumab (if applicable).

• Prior use of any monoclonal antibody, radioimmunoconjugate, orantibody-drugconjugate as anti-cancer therapy within 4 weeks before first studytreatment, except for the use of non-myeloma therapy

• Prior treatment with systemic immunotherapeutic agents, including, but not limitedto, cytokine therapy and anti-CTLA4, anti-PD-1, and antiPD-L1 therapeutic antibodieswithin 12 weeks or 5 half-lives of the drug, whichever is shorter, before firststudy treatment

• Prior treatment with chimeric antigen receptor T (CAR T)-cell therapy within 12weeks before first study treatment

• Treatment with radiotherapy within 4 weeks (systemic radiation) or 14 days (focalradiation) prior to first study treatment

• Treatment with any chemotherapeutic agent or other anti-cancer agent (investigational or otherwise) within 4 weeks or 5 half-lives of the drug, whicheveris shorter, prior to first study treatment

• Autologous SCT within 100 days prior to first study treatment

• Prior allogeneic stem cell transplant(ation) (SCT)

• Circulating plasma cell count exceeding 500/micro L or 5% of the peripheral bloodwhite cells

• Prior solid organ transplantation

• History of autoimmune disease

• History of confirmed progressive multifocal leukoencephalopathy

• History of severe allergic or anaphylactic reactions to monoclonal antibody therapy

• Known history of amyloidosis

• Lesions in proximity of vital organs that may develop suddendecompensation/deterioration in the setting of a tumor flare

• History of other malignancy within 2 years prior to screening

• Known treatment-related, immune-mediated adverse events associated with priorcheckpoint inhibitors

• Current or past history of central nervous system (CNS) disease, such as stroke,epilepsy, CNS vasculitis, neurodegenerative disease, or CNS involvement by MM

• Significant cardiovascular disease

• Symptomatic active pulmonary disease or requiring supplemental oxygen

• Known active bacterial, viral, fungal, mycobacterial, parasitic, or other infection

• Known or suspected chronic active Epstein-Barr virus (EBV) infection

• Recent major surgery within 4 weeks prior to first study treatment

• Positive serologic or PCR test results for acute or chronic hepatitis B virus (HBV)infection

• Acute or chronic hepatitis C virus (HCV) infection

• Known history of Grade >= 3 CRS or immune effector cell-associated neurotoxicitysyndrome (ICANS) with prior bispecific therapies

• Known history of hemophagocytic lymphohistiocytosis (HLH) or macrophage activationsyndrome (MAS)

• Active symptomatic coronavirus disease 2019 (COVID-19) infection at study enrollmentor requiring treatment with intravenous (IV) antiviral where the last dose of IVantiviral treatment was given within 14 days prior to first study treatment.Patients with active COVID-19 infection must have clinical recovery and two negativeantigen tests at least 24 hours apart prior to first study treatment

• Positive and quantifiable EBV polymerase chain reaction (PCR) or Cytomegalovirus (CMV) PCR prior to first study treatment

• Known history of HIV seropositivity

• Administration of a live, attenuated vaccine within 4 weeks before first studytreatment or anticipation that such a live attenuated vaccine will be requiredduring the study

• Treatment with systemic immunosuppressive medications, with the exception ofcorticosteroid treatment <=10 mg/day prednisone or equivalent, within 2 weeks priorto first study treatment

• History of illicit drug or alcohol abuse within 12 months prior to screening, in theinvestigator's judgment Additional Arm B-Specific Exclusion Criteria

• Pregnant or breastfeeding, or intending to become pregnant 4 weeks prior toinitiation of study treatment, during the study, (including treatment interruptions)or within 4 weeks after the last dose of pomalidomide

• Significant cardiovascular disease (such as, but not limited to, New York HeartAssociation Class III or IV cardiac disease, myocardial infarction within the last 12 months, uncontrolled arrhythmias, or unstable angina)

• History of erythema multiforme, Grade >=3 rash, blistering, or severehypersensitivity to prior treatment with immunomodulatory drugs such as thalidomide,lenalidomide, or pomalidomide

• Inability to tolerate thromboprophylaxis, or contraindication to thromboprophylaxis

• GI disease that might significantly alter absorption of oral drugs Additional ArmC-Specific Exclusion Criteria

• Pregnant or breastfeeding, or intending to become pregnant during the study orwithin 102 days after the last dose of daratumumab

• Known hypersensitivity to biopharmaceuticals produced in CHO cells or any componentof daratumumab formulations

• Known chronic obstructive pulmonary disease (COPD) with a forced expiratory volumein 1 second (FEV1) <50% of predicted normal

• Known moderate or severe persistent asthma within the past 2 years, or currentuncontrolled asthma of any classification