A Study Evaluating the Prophylactic Use of Tocilizumab to Prevent Cytokine Release Syndrome With Ramantamig Administration in Participants With Relapsed/Refractory Multiple Myeloma

Inclusion criteria:

* Documented diagnosis of multiple myeloma (MM) as defined by the criteria: a. MM diagnosis according to the international myeloma working group (IMWG) diagnostic criteria; b. Measurable disease at screening as assessed by local laboratory as defined in the protocol
* Received at least 1 prior lines of antimyeloma therapy
* Relapsed or refractory disease as defined: a. Relapsed disease is defined as an initial response to prior treatment, followed by confirmed progressive disease (PD) by the IMWG response criteria greater than (\>) 60 days after cessation of treatment.; b. Refractory disease is defined as failure to achieve a response (that is, partial response or better) or confirmed PD by the IMWG response criteria during previous treatment or less than or equal to (\<=) 60 days after cessation of treatment
* Have an eastern cooperative oncology group (ECOG) performance status (PS) score of 0 to 2 at screening and immediately before the start of study treatment administration. Participants with ECOG PS 2 or 3 are eligible for the study if the ECOG PS score is related to stable physical limitations (example, wheelchair-bound due to prior spinal cord injury) and not related to MM or associated therapy
* Have clinical laboratory values meeting the criteria specified in the protocol during the screening and within 1 day of the start of administration of study treatment

Exclusion criteria:

* Concurrent use of any other anticancer treatment (including non-palliative radiotherapy) or investigational agent
* Major surgery, (for example, requiring general anesthesia) within 2 weeks before first dose, or will not have fully recovered from surgery, or has surgery planned during the time the participant is expected to participate in the study
* Suspected or known allergies, hypersensitivity, or intolerance to ramantamig and tocilizumab or their excipients
* Presence of any of the following: a. Any ongoing myelodysplastic syndrome or B-cell malignancy (other than MM); b. Any history of malignancy, other than MM, that is considered at high risk of recurrence requiring systemic therapy; c. Any active malignancy other than MM that is considered at high risk of recurrence requiring systemic therapy
* Known active or prior central nervous system (CNS) involvement or exhibits clinical signs of meningeal involvement of MM. If either is suspected, negative whole brain magnetic resonance imaging (MRI) and lumbar cytology are required