Dual Targeting of Extramedullary Myeloma with Talquetamab and Teclistamab

Patients with plasmacytomas that are noncontiguous with bone marrow (true extramedullary myeloma) are at high risk for disease progression or relapse. Phase 1 of the RedirecTT-1 study showed promising efficacy with dual-antigen targeting of myeloma with talquetamab (anti-G protein-coupled receptor family C group 5 member D) plus teclistamab (anti-B-cell maturation antigen) in patients with triple-class-exposed relapsed or refractory multiple myeloma, including those with true extramedullary myeloma.

In this phase 2 study, we investigated talquetamab plus teclistamab exclusively in patients with drug-resistant, true extramedullary myeloma. The primary end point was overall response, evaluated with the use of functional imaging. Secondary end points included the duration of response, progression-free survival, overall survival, and safety.

A total of 90 patients were enrolled in the study and received treatment (median follow-up, 12.6 months). A response occurred in 79% of the patients (95% confidence interval [CI], 69 to 87). Among the patients with a response, the percentage with a response duration of at least 12 months was 64% (95% CI, 48 to 76). At 12 months, progression-free survival was 61% (95% CI, 50 to 71), and overall survival was 74% (95% CI, 63 to 83). Common adverse events of any grade included oral symptoms, such as dysgeusia, dry mouth, and dysphagia (in 87% of the patients); cytokine release syndrome (in 78%); and nonrash skin effects (in 69%). Grade 3 or 4 adverse events (most commonly hematologic events) occurred in 76% of the patients; 31% had grade 3 or 4 infection. A nonfatal adverse event led to discontinuation of one or both agents in 6% of the patients. Among 10 deaths that occurred during follow-up, 5 were due to infection and 5 were considered to be related to the study treatment.

Most patients with drug-resistant, true extramedullary myeloma had a response with talquetamab plus teclistamab. The incidence of adverse events of grade 3 or above was high and was consistent with previous observations for each agent as monotherapy. (Funded by Johnson & Johnson; RedirecTT-1 ClinicalTrials.gov number, NCT04586426.).