Inclusion Criteria:

• Eastern Cooperative Oncology Group Performance Status (ECOG) of 0-1.
• Patients with relapsed or refractory MM who have failed or are intolerant to all therapies with known clinical benefit; patients must have received at least 2 prior anti-myeloma therapies which must contain at least one proteasome inhibitor (PI), one immunomodulatory drug (IMiD), and one anti-CD38 monoclonal antibody (if available).

Exclusion Criteria:

• Patients who had received BCMA-targeted therapy.
• Patients who had received CAR-T therapy.
• Patients who had received anti-tumor therapy within 3 weeks or 5 half-lives (whichever is shorter) prior to the first dose of CM336.