Talquetamab in Japanese patients with relapsed/refractory multiple myeloma in the MonumenTAL-1 study

Talquetamab is the first G protein-coupled receptor family C group 5 member D (GPRC5D) × CD3 bispecific antibody approved for relapsed/refractory multiple myeloma (RRMM). We report the first efficacy and safety results of talquetamab in Japanese patients enrolled as a separate cohort in the global MonumenTAL-1 study. Between July 2022 and December 2023, 36 patients were enrolled and received 0.4 mg/kg talquetamab weekly. Median follow-up was 13.4 months. The overall response rate was 77.8% (55.6% achieved complete response or better). Median time to first response was 1.2 months. Twelve-month duration of response, progression-free survival, and overall survival rates were 66.4%, 56.3%, and 74.1%, respectively. On-target, off-tumor adverse events (AEs), including taste-, skin- (non-rash), nail-, and rash-related AEs, were common (80.6%, 66.7%, 55.6%, and 36.1%, respectively) and mostly grade 1/2. Cytokine release syndrome occurred in 75.0% of patients; all events were grade 1/2. The rate of infection was 52.8%; the rate of grade 3/4 infection was 16.7% (one led to death [pneumonia]). One patient discontinued talquetamab and three patients died due to AEs. Results were generally consistent with the global MonumenTAL-1 population, demonstrating talquetamab as an important novel treatment for Japanese patients with RRMM. Clinical trial registration number: NCT03399799/NCT04634552.