Radiation Combined With BCMA/CD3 Bispecific Antibody Therapy for Solitary Bone Plasmacytoma With Mild Bone Marrow Infiltration

Inclusion Criteria: * ≥18 years old * Histologically confirmed SBP with \<10% clonal plasma cells in marrow * ECOG ≤ 2 * No prior anti-myeloma therapy. Previous local radiotherapy for SBP is not an exclusion criterion. * Meets laboratory and imaging criteria Exclusion Criteria: 1. Patients who have previously received anti-plasma cell therapy, including melphalan, cyclophosphamide, proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, bispecific antibodies, or chimeric antigen receptor T-cell (CAR-T) therapy. 2. Any condition that, in the opinion of the investigator, would make the patient unsuitable for participation in this study.