The fully human anti-GPRC5D CAR T-cell therapy RD118 induces durable remissions in relapsed/refractory multiple myeloma

GPRC5D has emerged as a promising therapeutic target in relapsed/refractory multiple myeloma (R/R MM), particularly following progression after B-cell maturation antigen (BCMA)-directed chimeric antigen receptor (CAR) T-cell (CAR-T) therapies. RD118 is a novel CAR-T therapy incorporating a fully human single-domain antibody fragment targeting GPRC5D. In this phase 1 study, 18 R/R patients (17 with MM and 1 with a history of primary plasma cell leukemia) received a single infusion of RD118 at 1.0 × 106, 2.0 × 106, or 3.0 × 106 CAR+ T cells per kg. At a median follow-up of 17.0 months, the overall response rate (ORR) was 94.4%, including 72.2% complete or stringent complete responses. Among the 7 patients previously exposed to BCMA-directed CAR-T therapy, ORR reached 85.7%. Median progression-free survival (PFS) was 18.2 months (95% confidence interval, 14.4 to not estimable), with 12-month PFS and overall survival rates of 82.1% and 93.3%, respectively. Cytokine release syndrome occurred in 88.9% of the patients, primarily grade 1 to 2. One patient developed grade 3 immune effector cell-associated neurotoxicity, which resolved within 72 hours. No cerebellar toxicities or treatment-related deaths were reported. These findings support that RD118 is a highly effective and safe therapeutic option for heavily pretreated R/R MM. This trial was registered at www.clinicaltrials.gov as #NCT05759793 and #NCT05219721.