Efficacy, safety, and pharmacokinetics of teclistamab in Chinese patients with relapsed/refractory multiple myeloma from the China cohort of MajesTEC-1

Introduction: Teclistamab, the first approved B-cell maturation antigen-directed bispecific antibody for treatment of triple-class exposed relapsed/refractory multiple myeloma, demonstrated deep, durable responses with a manageable safety profile in the pivotal MajesTEC-1 cohort (NCT03145181/NCT04557098). Efficacy, safety, and pharmacokinetics from the MajesTEC-1 China cohort are reported. Methods: Patients received teclistamab 1.5 mg/kg subcutaneously weekly after step-up dosing; patients could switch to less frequent dosing with continued response. Results: In the China cohort (N = 26; median age, 66 years; median prior lines of therapy, 5) 15-month median follow-up, overall response rates, very good partial response or better, and complete response or better (≥CR) were 76.9%, 76.9%, and 57.7%, respectively. Median time to first response and ≥CR were 1.4 and 6.3 months, respectively; among patients with ≥CR and have available MRD samples, MRD negativity was achieved in 14/15 (93.3%) patients. Median duration of response, progression-free survival, and overall survival were not reached; 12-month duration of response, progression-free survival, and overall survival rates were 78.5%, 68.0%, and 83.5%, respectively. The safety profile was consistent with the pivotal cohort. Although infections occurred in 96.2% of patients, incidence decreased over time with six patients experiencing infections for >12 to 18 months. There were no discontinuations because of adverse events and no dose reductions. Ten patients switched to less frequent dosing. Teclistamab serum concentrations were consistent with the pivotal cohort, with a slightly lower mean pharmacokinetics profile. Conclusions: Teclistamab demonstrated efficacy and safety profiles in the China cohort consistent with the pivotal cohort, supporting teclistamab as a promising treatment option for triple-class exposed relapsed/refractory multiple myeloma in China.