P-032: Real-world analysis of teclistamab treatment for relapsed refractory multiple myeloma in two Belgian university hospitals

Introduction:
T-cell redirection therapies, either bispecific antibodies or CAR-T cells, are revolutionizing the treatment of multiple myeloma by achieving impressive and durable response rates in relapsed refractory disease (RRMM). Teclistamab (Tec) is the first BCMA x CD3 directed bispecific antibody to be approved for the treatment of patients (pts) with RRMM, based on the results of the pivotal phase 1/2 MajesTEC-1 trial. Recently available in Belgium, we report our real-world experience.

Methods:
We retrospectively evaluated the efficacy and tolerability of Tec in 16 patients treated in 2 Belgian academic hospitals to determine whether the outcome is comparable in the real-world setting. Tec was administered weekly at a dose of 1.5 mg/kg, after 2 step-up doses of 0.06 and 0.3 mg/kg, according to recommendations. High-risk (HR) cytogenetics was defined by the presence of t(4;14), t(14;16) and/or del(17p). Responses were defined according to the IMWG 2016 criteria. Survival analyses were performed using the Kaplan-Meier method. Adverse events (AEs) were graded according to CTCAE v5.0. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were graded according to ASTCT guidelines.

Results:
Between December 16, 2022 and April 22, 2024, 16 pts received at least 1 dose of Tec. Median age was 68 years, 56% were female, 33% had HR cytogenetics and 20% had stage III ISS.

Pts had received a median of 5 lines of therapy (LOT), 81.2% and 6.2% had triple or penta-refractory disease, respectively, and most (87.5%) were refractory to the last LOT. None had received prior BCMA-directed therapy, only 1 pt had been exposed to talquetamab.

With a median follow up of 6 months (range 0.8-16.2), the ORR was 93.7% with 81.2% of pts achieving at least VGPR. The median time to first/best response was 27/39 days, respectively. No mPFS, mDOR or mOS were achieved. All pts experienced at least 1 AE, grade (gr) ³3 in 75%. CRS occurred in 50% of pts (no gr³3), all during the step-up dose or cycle 1, 3 pts (18.7%) experienced ICANS (gr 3 in 1). Cytopenias were common (any gr/gr³3): anemia (100%/25%), neutropenia (81.2%/56.2%), thrombocytopenia (75%/18.7%) and lymphopenia (75%/31.2%). 41 infectious episodes were reported in 14 pts with an incidence (any gr/gr ³3) of 87.5%/43.7%. Respiratory infections were the most common (37%), followed by bacteremia (20%). COVID-19 infections occurred in 5 pts, influenza in 1, and esophageal candidiasis in 1. 87,5% of pts received immunoglobulin substitution.

Conclusions:
Tec showed a similar efficacy and safety profile in the real-world setting as in the pivotal trial and other real-world reports, with the exception of a higher ICANS rate, which is difficult to interpret due to several confounding factors. Of note, one patient with prior talquetamab exposure still had at least 12.6 months of VGPR at data cutoff.