CM336-SOC for Dynamically High-Risk Multiple Myeloma Study

Inclusion criteria

• Able to understand and voluntarily sign the informed consent form (ICF).
• Aged ≥18 and ≤75 years.
• Has measurable disease, meeting at least one of the following criteria: serum M-protein ≥5 g/L as measured by serum protein electrophoresis (SPEP); or, for IgA or IgD myeloma, quantitative IgA or IgD levels may be used instead; or urine M-protein ≥200 mg/24 hours; if neither serum nor urine M-protein meets the above criteria, involved serum free light chain (FLC) ≥100 mg/L in the presence of an abnormal serum FLC ratio (normal FLC ratio: 0.26 to 1.65).
• Has received only one prior line of standard anti-myeloma therapy: standard induction therapy comprising at least two of the following: a proteasome inhibitor, an immunomodulatory agent, and an anti-CD38 monoclonal antibody; followed by autologous hematopoietic stem cell transplantation or consolidation therapy, and standard maintenance therapy.
• Meets the definition of functional high-risk multiple myeloma according to the EMN consensus: disease progression or relapse within 18 months after initiation of any first-line therapy.
• Liver function tests meet the following criteria: total bilirubin <1.5 × upper limit of normal (ULN) (except that patients with Gilbert's syndrome must have total bilirubin <3 × ULN), and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤2.5 × ULN.
• Renal function tests meet the following criterion: creatinine clearance ≥30 mL/min, calculated using the Cockcroft-Gault formula.
• Complete blood count within 7 days before screening meets the following criteria: white blood cell (WBC) count ≥1.5 × 10⁹/L, absolute neutrophil count ≥1.0 × 10⁹/L, hemoglobin ≥70 g/L, and platelet count ≥75 × 10⁹/L if bone marrow plasma cells are <50%, or platelet count ≥50 × 10⁹/L if bone marrow plasma cells are ≥50%; or, in the investigator's judgment based on the actual clinical situation, the subject is considered suitable for enrollment.
• For patients receiving hematopoietic growth factor support, including erythropoietin, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and platelet agonists, etc. (e.g., eltrombopag, TPO, interleukin-11), there must be an interval of 2 weeks between growth factor support and screening assessment.
• For patients receiving blood product transfusions: there must be an interval of at least 2 weeks between the screening hemoglobin assessment and the last red blood cell (RBC) transfusion, and an interval of at least 1 week between the screening platelet assessment and the last platelet transfusion.
• The subject is able to receive the prophylactic anticoagulation recommended in the study.
• Female subjects of childbearing potential must meet both of the following conditions: agree to use effective contraception from the date of signing the informed consent form, during treatment with the study drug, and for 3 months after the last dose of the study drug; and have a negative serum pregnancy test result at screening.

Exclusion criteria

• Primary plasma cell leukemia or secondary plasma cell leukemia.
• Concurrent amyloidosis.
• Concurrent central nervous system (CNS) involvement.
• Prior treatment with BCMA-targeted therapy or CAR-T cell therapy.
• Known intolerance, allergy, or contraindication to glucocorticoids or BCMA/CD3 bispecific antibody products.
• Clinically significant cardiac disease, including: myocardial infarction before randomization; or unstable or uncontrolled disease related to or affecting cardiac function, such as unstable angina, congestive heart failure, or New York Heart Association class III-IV cardiac function. Uncontrolled arrhythmia or clinically significant ECG abnormalities. Baseline corrected QT interval (QTc) >470 msec on 12-lead ECG at screening.
• Known active human immunodeficiency virus (HIV) infection or HIV seropositivity.
• Active hepatitis B or C infection. Hepatitis serology testing is required at screening. If hepatitis B surface antigen or hepatitis B core antibody is positive, a negative DNA polymerase chain reaction (PCR) result must be confirmed before enrollment; for patients receiving anti-hepatitis B antiviral therapy, a negative DNA PCR result must be confirmed before enrollment. If hepatitis C antibody is positive, RNA PCR testing must be performed, and a negative result must be confirmed before enrollment.
• Pregnant or breastfeeding women.
• Life expectancy <6 months.
• Any active gastrointestinal dysfunction that affects the patient's ability to swallow tablets, or any active gastrointestinal dysfunction that may affect absorption of the study treatment.
• Major surgery within 2 weeks before the start of randomization, such as surgery requiring general anesthesia; incomplete recovery from surgery; or planned surgery during the study period. Kyphoplasty or vertebroplasty is not considered major surgery.

Note: Subjects scheduled to undergo surgical procedures under local anesthesia may participate in the study.

• Receipt of a live attenuated vaccine within 4 weeks before the first dose of study drug.