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

Phase 2RecruitingNCT07115667

Institute of Hematology & Blood Diseases Hospital, China21 enrolled

Overview

This is a prospective, single-arm, single-center clinical trial designed to evaluate the safety and efficacy of radiation combined with a BCMA/CD3 bispecific antibody (CM336) in patients with solitary bone plasmacytoma (SBP) with mild bone marrow infiltration. SBP is a rare plasma cell malignancy with a high risk of progression to multiple myeloma (MM), particularly in patients with minimal bone marrow involvement. Although radiotherapy is the standard treatment, it is often insufficient to eradicate clonal plasma cells and prevent progression in high-risk patients. CM336, a novel BCMA/CD3 bispecific antibody, has demonstrated promising activity in relapsed/refractory multiple myeloma. In this trial, eligible patients will receive radiotherapy followed by a 12-cycle limited treatment course of CM336, aiming to achieve deep clearance of residual malignant cells and reduce progression risk.

Study Type

INTERVENTIONAL

Allocation

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Solitary Bone Plasmacytoma Plasmacytoma of Bone

Eligibility

Sex: ALLMin age: 18 YearsMax age: 78 Years

Medical Language ↔ Plain English

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.

Outcomes

Primary Outcomes

Safety and Tolerability

The primary outcome is to evaluate the safety and tolerability of the combination therapy. This includes the incidence, severity, and type of adverse events (AEs) and serious adverse events (SAEs), graded according to NCI CTCAE v5.0. Particular attention will be paid to cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Safety assessments will include laboratory parameters, vital signs, ECGs, and clinical symptoms.

Time frame: From first dose through 28 days after last dose

Secondary Outcomes

Progression-Free Survival (PFS)

PFS is defined as the time from the start of treatment to the first documentation of disease progression or death from any cause, whichever occurs first. Disease progression will be assessed using IMWG criteria for progression from solitary plasmacytoma to multiple myeloma.

Time frame: Up to 5 years

Multiple Myeloma Free Survival (MMFS)

MMFS is defined as the time from the start of treatment to the first documented diagnosis of multiple myeloma, based on IMWG criteria. Patients who do not progress to MM will be censored at the date of last follow-up. The diagnosis of MM will be confirmed by clinical, laboratory, and imaging criteria.