Long-Term Follow-up of Real-World Teclistamab Therapy for Relapsed/Refractory Multiple Myeloma from the IMWG Immunotherapy Working Group Committee

Introduction: Teclistamab (Tec) is the first approved BCMA x CD3 bispecific antibody for the treatment of triple-class-exposed patients with relapsed/refractory multiple myeloma (RRMM) based on the pivotal MajesTEC-1 study. Tec was associated with high overall response rate (ORR) of 63% in heavily pretreated patients. After a longer follow-up of 30.4 months, CR rate was 46.1%, median duration of response (DOR) was 24 months (95% CI, 17.0 - not estimable), and median progression-free survival (PFS) was 11.4 months (95% CI, 8.8 - 16.4). Herein, we present updated analysis of real-world outcomes and safety with tec in RRMM with extended follow-up of more than 12 months. Methods: This is an international multicenter retrospective study of patients with RRMM treated with tec on-label at 9 academic centers from 5 countries (United States, United Kingdom, Greece, Spain, and Canada) through the International Myeloma Working Group (IMWG) Immunotherapy Committee. Patients with RRMM treated with commercial tec at the respective institutions between May 24, 2022 to January 4, 2024 were included. Median follow-up was 14 months with data collected until July 15, 2024. High-risk cytogenetic abnormalities (HRCA) was defined as 1q+, t(4;14), t(14;16), t(14;20), and/or del(17p). Response was assessed using the IMWG consensus criteria. Patient characteristics were summarized by frequency (percentage) or median (interquartile range [IQR] or range). PFS, overall survival (OS), DOR were evaluated using the Kaplan-Meier method. Results: There were 223 patients included in this analysis with the following characteristics: median age of 67 (range 33-91) with 24% ≥75 years; 45% female; 74% White, 10% Black, 9% Asian, and 7% other/unknown; 86 of 176 (49%) with high risk cytogenetics, including del(17p), t(4;14), t(14;16), t(14;20), and gain/amp 1q; 29.4% (37/126) with known extramedullary disease; 14% with creatinine clearance ≤30 ml/min. Patients received a median of 6 (IQR, 4-8) prior lines of therapy with 52% (107/206) being penta-drug refractory. Among 212 patients with available data, 161 (75.9%) patients would have been ineligible for MajesTEC-1. There were 94 (42%) patients who received prior BCMA-directed therapy (29.8% antibody-drug conjugate [ADC] alone; 45.7% CART alone; 6.3% bispecific antibody alone; 17.0% ADC and CART). Median time from diagnosis to tec initiation was 6.1 (range 0.6-29.2) years. For the 206 response-evaluable patients, ORR was 66%, including 25.2% ≥CR, 33.5% VGPR, and 7.3% PR. ORR for the 90 response-evaluable patients with prior BCMA-directed therapy was 54.5% (21.1% ≥CR, 26.7% VGPR, 6.7% PR). After a median follow-up of 14 (95%CI, 13-14) months, median PFS and OS were 8.8 (95% CI, 5.5-14) and 20 (95% CI, 18-not reached [NR]) months, respectively. 12-month PFS estimate was 46% (95% CI, 40%-54%), and 12-month OS rate was 65% (95% CI, 59%-72%). Median DOR was 17 (95% CI, 17-NR) months with 12-month estimate of 68% (95% CI, 60%-77%). Tec step-up dosing occurred in the outpatient setting for 57 (25.6%) patients. CRS occurred in 119 out of 222 (53.6%) patients with almost all being grade 1-2, except for 1 grade 4 event. ICANS occurred in 18 out of 216 (8.3%) patients (grade 1-2: 5.1%; grade 3-4: 2.8%). Any grade infection occurred in 130 (58.3%) patients; 25.1% of patients had grade ≥3 infection, including 10 patients with grade 5 infection. While receiving teclistamab, 79 (35.4%) patients had ≥2 infections. IVIG was given in 114 out of 164 (69.5%) patients. Conclusion: In this multicenter international real-world analysis of outcomes and safety associated with tec, ORR was high at 66% with 25.2% of patients achieving ≥CR. CR rates may be underestimated due to infrequent bone marrow confirmation in the real-world datasets. Encouragingly, ORR was 54.5% in BCMA exposed RRMM patients, including 21.1% with ≥CR. After a median follow-up of 14 months, heavily pretreated patients including patients with prior BCMA therapy had durable responses with median PFS of 8.8 months and median DOR of 17 months. There were no new safety signals noted in this real-world study. This is the largest real-world study to date of teclistamab with long-term follow-up of more than 12 months. Additional data including more patients, longer follow-up and results from difficult to treat subgroups will be presented at the meeting.