ASCT Combined With BCMA CAR-T and GPRC5D/CD3 BiTEs Maintenance for Transplant-Eligible Ultra-High-Risk Multiple Myeloma

This is a prospective, single-arm, phase II study to evaluate the efficacy and safety of autologous stem cell transplantation combined with BCMA CAR-T therapy followed by GPRC5D/CD3 bispecific antibody maintenance in transplant-eligible patients with ultra-high-risk multiple myeloma.

Inclusion Criteria: 1. Age ≥ 18 years and ≤ 70 years. 2. Participants with documented newly-diagnosed multiple myeloma according to IMWG diagnostic criteria. 3. Measurable disease at screening, defined as: Serum M-protein level ≥1.0 g/dL or urine M-protein level ≥200 mg/24 hours; or Light chain MM without measurable disease in serum or urine: serum Ig free-light chain (FLC) ≥10 mg/dL and abnormal serum Ig kappa lambda FLC ratio. 4. Patients deemed eligible for high-dose chemotherapy with ASCT. 5. Presence of at least one of the following ultra-high-risk features: a. Double-hit multiple myeloma, defined as the presence of at least two of the following high-risk cytogenetic abnormalities: t(4;14), t(14;16), deletion 1p, gain 1q, MYC rearrangement, deletion 17p, or TP53 mutation; b. Presence of extramedullary soft tissue plasmacytomas; c. Circulating plasma cells ≥2% in peripheral blood. 6. Tumor cells were BCMA and GPRC5D positive. 7. Serum total bilirubin \