Sequencing T-cell Redirection Therapies Leads to Deep and Durable Responses in Patients with Relapsed/refractory Myeloma

T-cell redirection therapy using chimeric antigen receptor (CAR) T cells and bispecific antibodies (BiAbs) has shown promising efficacy in heavily pretreated patients with relapsed/refractory multiple myeloma (RRMM), leading to the approval of 2 CAR T-cell products and numerous BiAb trials. Data on the outcomes after relapse following BiAbs are urgently required to develop strategies for sequencing salvage therapies. We identified 58 patients progressing after a BiAb trial at Mount Sinai Hospital. Progression-free survival (PFS) to the first salvage (PFS1), second salvage therapy (PFS2), and overall survival (OS) were estimated using the Kaplan-Meier method. The median age of the patients was 67 years, and 78% had high-risk cytogenetics. They had a median of 6 prior therapy lines, 89% were triple-class refractory, and 44% were penta-drug refractory. After the BiAb trial, patients were followed for a median of 30.5 months and received a median of 2 additional salvage therapies (range, 1-9). The most common first salvage was T-cell redirection in 19 patients (10 BiAb and 9 CAR T cells). Ten patients underwent T-cell redirection as a second salvage treatment. T-cell redirection therapy as first or second salvage was feasible and associated with a median PFS1 of 28.9 months, PFS2 of 30.9 months, and an OS of 62% at 2 years. The sequential use of different T-cell redirection therapies is possible and may lead to deep and durable responses following the relapse after BiAb therapy in RRMM.