A Study of GR1803 Injection Versus Daratumumab, Pomalidomide, and Dexamethasone (DPd) in Participants With Relapsed or Refractory Multiple Myeloma

A Phase 3, Multicenter, Open-Label, Randomized Study Comparing GR1803 Injection Versus Daratumumab, Pomalidomide, and Dexamethasone (DPd) in Participants With Relapsed or Refractory Multiple Myeloma Who Have Received 1 to 3 Prior Lines of Therapy Including Lenalidomide and Proteasome Inhibitors

The purpose of this study is to compare the efficacy of GR1803 Injection with daratumumab in combination with pomalidomide and dexamethasone (DPd).

Study Overview

• Status: Recruiting
• Conditions: Multiple Myeloma
• Intervention / Treatment: Drug: GR1803 injection; Drug: Daratumumab; Drug: Pomalidomide; Drug: Dexamethasone

• Study Type: Interventional
• Enrollment (Estimated): 358
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Gang An; Phone Number: 13502181109; Email: angang@ihcams.ac.cn

Study Locations

• China
  • Tianjin, China
    • Recruiting
    • Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences
    • Contact: Gang An; Phone Number: 13502181109; Email: angang@ihcams.ac.cn

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Have an eastern cooperative oncology group (ECOG) performance status score of 0, 1, or 2 at screening and baseline.
• Diagnosed as multiple myeloma according to the diagnostic criteria of the International Myeloma Working Group (IMWG) diagnostic criteria.
• Received 1 to 3 prior line(s) of antimyeloma therapy including a proteasome inhibitor (PI) and lenalidomide; a. participants who have received only 1 line of prior line of antimyeloma therapy must be lenalidomide refractory. Stable disease or progression on or within 60 days of the last dose of lenalidomide given as maintenance will meet this criterion.
• Documented evidence of progressive or stable disease based on investigator's determination of response by IMWG criteria on or after their last regimen.
• Measurable disease at screening and baseline as defined by any of the following: 1) serum M-protein level greater than or equal to (>=) 5 gram per liter (g/L); or 2) urine M-protein level >=200 milligrams (mg)/24 hours; or 3) serum immunoglobulin free light chain >=100 mg/L and abnormal serum immunoglobulin kappa lambda free light chain ratio.
• Have clinical laboratory values within the specified range.
• Have an understanding of and comply with the clinical trial protocol requirements, voluntarily participate in the clinical trial, and sign the informed consent form.

Exclusion Criteria:

• Plasma cell leukemia, Waldenström's macroglobulinemia, POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes), or amyloidosis (including primary and secondary).
• History or clinical signs of central nervous system involvement or meningeal involvement of multiple myeloma .
• Received any prior B cell maturation antigen (BCMA)-directed therapy.
• Has disease that is considered refractory or intolerant to an anti-cluster of differentiation 38 (CD38) targeted therapy or Pomalidomide.
• Prior antitumor therapy, within 21 days (PI 、IMiDs or radiotherapy within 14 days, clinical trial vaccine within 28 days, Gene modified adoptive cell therapy within 3 months, allogeneic stem cell transplantation within 6 months, autologous stem cell transplantation within 12 weeks) prior to first dose of study drug.
• Received a cumulative dose of corticosteroids equivalent to >=140 mg of prednisone within 14 days prior to first dose of study drug.
• Grade >= 2 peripheral neuropathy at screening.
• History of Guillain Barre Syndrome (GBS) or variant GBS.
• The following medical conditions: active infecion, human immunodeficiency virus (HIV) infection, hepatitis B or C infection, Syphilis infection, thromboembolic events or cerebrovascular events less than or equal to (<=) 6 m, seizure attacks less than or equal to (<=) 6 m.
• Active malignancies other than relapsed/refractory multiple myeloma within 3 years prior to screening.
• Active autoimmune disease or history of autoimmune disease.
• Received a live, attenuated vaccine within 4 weeks before first dose of study drug.
• Have major surgery within 2 weeks before first dose of study drug.
• Contraindications or life-threatening allergies, hypersensitivity, or intolerance to any study drug or its excipients.
• Pregnant, lactating female.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Arm A: GR1803 Injection	Drug: GR1803 injection; Participants received intravenous GR1803 injection at a dose of 180 ug per kilogram, which had been preceded by step-up doses of 10 and 30 ug per kilogram.
Active Comparator: Arm B: DPd	Drug: Daratumumab; Participants received subcutaneous Daratumumab at a dose of 1800 mg.; Drug: Pomalidomide; Participants received Pomalidomide at a dose of 4 mg on days 1 to 21 of each cycle (28 days).; Drug: Dexamethasone; Participants received once-weekly dexamethasone at a dose of 40 mg (≤75 years) or 20 mg (>75 years).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Progression Free Survival (PFS)	Up to 5 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Overall Survival (OS)		Up to 5 years
Duration of Response		Up to 5 years
Progression Free Survival on Next-line Therapy (PFS2)		Up to 5 years
Overall Response (Partial Response [PR] or Better)		Up to 5 years
Complete Response (CR) or Better		Up to 5 years
Duration of Complete Response		Up to 5 years
Time to Response		Up to 5 years
Minimal Residual Disease (MRD)-negativity		Up to 5 years
Number of Participants with Adverse Events (AEs) by Severity		Up to 5 years
Serum Concentration of GR1803 Injection		Up to 5 years
Number of Participants with Anti-drug Antibodies (ADAs) to GR1803 Injection		Up to 5 years
Change from Baseline in Overall Health-related Quality of Life as Assessed by EuroQol Five Dimension Questionnaire 5-Level (EQ-5D-5L)	The EQ-5D-5L ranges from 0 (worst imaginable health state) to 100 (best imaginable health state).	Up to 5 years

Collaborators and Investigators

• Sponsor: Genrix (Shanghai) Biopharmaceutical Co., Ltd.

Study record dates

Study Major Dates

• Study Start (Actual): March 9, 2026
• Primary Completion (Estimated): March 1, 2029
• Study Completion (Estimated): March 1, 2030

Study Registration Dates

• First Submitted: February 28, 2026
• First Submitted That Met QC Criteria: February 28, 2026
• First Posted (Actual): March 5, 2026

Study Record Updates

• Last Update Posted (Actual): March 25, 2026
• Last Update Submitted That Met QC Criteria: March 23, 2026
• Last Verified: February 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; Polycyclic Compounds; Pregnadienes; Pregnanes; Steroids; Fused-Ring Compounds; Steroids, Fluorinated; Pregnadienetriols; Dexamethasone; pomalidomide; daratumumab
• Other Study ID Numbers: GR1803-004

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