BCMA/CD3 Bispecific Antibody as Bridging Therapy Before CAR-T Cell Infusion in RRMM (CM336-001)

A Prospective Single-Arm, Single-Center Study of BCMA/CD3 Bispecific Antibody as Bridging Therapy Before CAR-T Cell Infusion in Relapsed or Refractory Multiple Myeloma

This study is a prospective, single-arm, multicenter trial designed to evaluate the hematologic response rate and safety of BCMA/CD3 bispecific antibody bridging therapy prior to CAR-T cell infusion in patients with relapsed/refractory multiple myeloma (RRMM).

Study Overview

• Status: Not yet recruiting
• Conditions: Relapsed Refractory Multiple Myeloma (RRMM)
• Intervention / Treatment: Biological: CM336 (BCMA/CD3 bispecific antibody)

• Study Type: Interventional
• Enrollment (Estimated): 10
• Phase: Phase 1

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 1.Voluntary Participation: Ability to understand and voluntarily sign the informed consent form (ICF).2.Age ≥18 years.3.Confirmed symptomatic MM diagnosis per the Chinese Guidelines for Diagnosis and Management of Multiple Myeloma (2022 Revision).4.Relapsed/Refractory MM (RRMM) meeting one of the following:Triple-class refractory RRMM: Resistant to ≥1 immunomodulatory drug (IMiD), ≥1 proteasome inhibitor (PI), and ≥1 anti-CD38 monoclonal antibody.Penta-drug refractory RRMM: Resistant to ≥2 IMiDs, ≥2 PIs, and ≥1 anti-CD38 antibody.Secondary plasma cell leukemia (sPCL):MM diagnosis per Chinese Guidelines (2022), plusPeripheral blood plasma cells ≥20% of leukocytes or absolute circulating plasma cells >2×10⁹/L.5.Successful apheresis for CAR-T cell manufacturing.6.ECOG performance status ≤3.7.No active infections:HBV-DNA negative, HCV-RNA negative, HIV negative.8.Liver function:Total bilirubin <1.5×ULN (<3×ULN for Gilbert's syndrome).AST/ALT <3×ULN.9.Renal function: Calculated CrCl ≥30 mL/min (Cockcroft-Gault formula).10.Baseline oxygen saturation >92% (room air).11.Hematologic criteria (within 7 days of screening):WBC ≥1.0×10⁹/L, ANC ≥1.0×10⁹/L, hemoglobin ≥70 g/L, andPlatelets ≥75×10⁹/L (or ≥50×10⁹/L if bone marrow plasma cells ≥50%).Investigator discretion permitted for clinical justification.12.Growth factor restrictions:2-week washout required for erythropoietin, G-CSF, GM-CSF, or thrombopoietin agonists (e.g., eltrombopag).13.Reproductive requirements:Non-childbearing women eligible;Childbearing potential women: Negative serum/urine pregnancy test (β-hCG) at screening.14.Contraception:Males/females of reproductive potential must use effective contraception (per investigator judgment) during treatment and for ≥3 months post CAR-T infusion.15.Sperm donation prohibition: Males must refrain from sperm donation from screening until 90 days post-treatment.16.Compliance: Willing and able to complete study procedures and follow-up.

Exclusion Criteria:

• 1.Prior GPRC5D-targeted immunotherapy.2.Investigator-assessed contraindications to GPRC5D×CD3 bispecific antibody therapy (e.g., severe cardiopulmonary diseases incompatible with treatment).3.Grade >2 peripheral neuropathy or ≥grade 2 painful neuropathy at screening (regardless of current medication).4.Known intolerance, hypersensitivity, or contraindication to GPRC5D×CD3 bispecific antibody components.5.Initiation of bridging therapy for BCMA CAR-T cell treatment.6.Unstable/active cardiovascular or cerebrovascular disease, including any of:a. Unstable angina, symptomatic myocardial ischemia, myocardial infarction, or coronary revascularization within 180 days prior to first dose.b. Uncontrolled hypertension (>140/90 mmHg with historical readings >180/100 mmHg within 6 months).c. Clinically significant uncontrolled arrhythmias (excluded: asymptomatic 1st-degree AV block or LAFB/RBBB).d. LVEF <40% by echocardiography.e. Stroke or intracranial hemorrhage within 12 months before screening.f. Pre-treatment severe thrombotic events.7.Active HIV infection or seropositivity.8.Active HBV/HCV infection:HBV: HBsAg(+) requires confirmed negative HBV-DNA PCR (allowed: if on antiviral therapy with confirmed suppression).HCV: HCV Ab(+) requires negative HCV-RNA PCR.9.Pregnancy or lactation.10.Active gastrointestinal disorders affecting swallowing or drug absorption.11.Major surgery within 2 weeks pre-enrollment or planned during study (excluded: kyphoplasty/vertebroplasty; allowed: local anesthesia procedures).12.Live vaccines within 4 weeks before first study dose.13.Active psychiatric/medical conditions impairing compliance/consent capacity per investigator judgment.14.Contraindications to required concomitant medications/supportive care.15.Any condition interfering with study procedures.16.Inability/unwillingness to comply with protocol.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: CM336	Biological: CM336 (BCMA/CD3 bispecific antibody); CM336 is a BCMA × CD3 bispecific antibody.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Safety and Tolerability	The incidence of treatment-emergent adverse events (TEAES)	Minimum 2 years after infusion
Overall Response Rate (ORR)	The proportion of subjects achieving stringent complete response (sCR), complete response (CR), very good partial response (VGPR), and partial response (PR) after treatment with CM336 injection	Minimum 2 years after infusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Duration of Response (DOR)	Duration of response (DOR) was defined as the time from first documented hematologic response (≥ partial response [PR]) to disease progression or death due to progression, whichever occurred first	Minimum 2 years after infusion
Overall Survival (OS)		Minimum 2 years after infusion
Progression-Free Survival (PFS)		Minimum 2 years after infusion
Time to Response (TTR)	Time from first BCMA × CD3 bispecific antibody infusion to first hematologic response， Depth of best hematologic response: The highest-level response achieved at any timepoint.	Minimum 2 years after infusion.

Collaborators and Investigators

• Sponsor: Institute of Hematology & Blood Diseases Hospital, China

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): May 31, 2027
• Study Completion (Estimated): May 31, 2028

Study Registration Dates

• First Submitted: February 6, 2026
• First Submitted That Met QC Criteria: February 6, 2026
• First Posted (Actual): February 12, 2026

Study Record Updates

• Last Update Posted (Actual): February 12, 2026
• Last Update Submitted That Met QC Criteria: February 6, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Neoplasms; Immune System Diseases; Neoplasms by Histologic Type; Hematologic Diseases; Lymphoproliferative Disorders; Immunoproliferative Disorders; Neoplasms, Plasma Cell; Hemostatic Disorders; Paraproteinemias; Blood Protein Disorders; Hemorrhagic Disorders; Hemic and Lymphatic Diseases; Multiple Myeloma
• Other Study ID Numbers: IIT2024047

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No