BCMA/CD3 BsAb in the Treatment of High-risk Smoldering Multiple Myeloma

The purpose of this study is to evaluate the safety and efficacy of CM-336, which is a BCMA/CD3 BiTE, in the treatment of high risk smoldering multiple myeloma.

Inclusion Criteria: 1. Know and voluntarily sign an informed consent form (ICF). 2. Age ≥18 years. 3. Definite diagnosis of SMM: According to IMWG Criteria 10, the patient must have histologically or cytologically confirmed smoldering multiple myeloma (SMM), including: 1. Serum M protein ≥3 g /dL and/or BMPCs≥10%(but not more than 60%) 2. No anemia: hemoglobin ≥10 g /dL 3. No renal failure: serum creatinine ≥2.0 mg/dL 4. No hypercalcemia: calcium ≥10.5 mg/dL 5. dissolving bone lesions without radiographic indications: X-ray, CT, or positron emission tomography (PET)/CT without dissolving bone lesions, with no more than 1 lesion on whole-body MRI (Note: In the investigator's judgment, whole-body CT or PET/CT may replace MRI for patients with contraindications or for whom MRI is not available). 6. FLC ratio \ 2 g/dL ② The ratio of affected to unaffected FLC was \> 20 ③BMPC \> 20% of the 3 items meet any 2 or more (ii) IMWG 2020 * FLC ratio 0-10: 0 points 10-25: 2 points 25-40: 3 points \>40: 5 points ②M protein (g/dL) 0-1.5: indicates 0 points 1.5-3: 3 points \>3: 4 points ③BMPC (%) 0-15: 0 points 15-20: 2 points 20-30: 3 points 30-40: 5 points \>40: 6 points ④FISH \* : Yes: 2 points None: 0 points The sum of the four points is greater than or equal to 9 （iii）Progression model * Necessary condition: BMPC\>10% ② Sufficient conditions: a. Serum M protein \>3 g/dL b. IgA type SMM c. Immune paralysis (reduction of two uninvolved homologous immunoglobulins) d. The proportion of free light chain (FLC) in serum that is affected/not affected \> 8 (but \5×106/L or 5%) j. Merri indicates diffuse abnormalities or 1 focal lesion, and/or increased uptake of focal lesion in PET-CT class without underlying osteolytic osteopathy. Meet the necessary conditions, 1 or more sufficient conditions. \*FISH exceptions are defined as the presence of any of the following: t (4,14), t (14,16), 1 q amplification, del 13 qt, t (4,20) 5. ECOG physical status score ≤2 points. 6. Meeting the following laboratory indicators within 28 days prior to study participation: a. neutrophils absolute value (ANC) \>1000/ml b. Platelet count (PLC)\> 75,000 /ml c. Total bilirubin ≤2 mg/dL d. Glutamic oxalic aminotransferase (AST) \