Real-world schedule de-escalation of teclistamab in patients with relapsed/refractory multiple myeloma.

7536 Background: Teclistamab (Tec) is the first BCMAxCD3 bispecific antibody approved for triple-class-exposed relapsed/refractory multiple myeloma (RRMM). The MajesTEC-1 study demonstrated an overall response rate (ORR) of 63% and a median progression-free survival (mPFS) of 11.3 months (mos). Herein, we examined real-world pt characteristics and outcomes associated with Tec in (1) pts treated within the first 4 mos of Tec approval (early initiators who were expected to have high disease burden) as compared to recent initiators, and (2) any pts who switched to de-escalated dosing schedules. Methods: This is a retrospective study of pts with RRMM treated with Tec at Memorial Sloan Kettering Cancer Center from 11/29/22 to 11/30/23 (analysis cut-off: 12/31/23). Responses were evaluated per IMWG Response Criteria. Pt characteristics were summarized by frequency (%) or median (interquartile range IQR). PFS was evaluated using the Kaplan-Meier method. Results: In 77 pts who received ≥1 Tec dose, the median age was 70 (IQR 63-77); 55% male; 14% Black; and 42% had high-risk cytogenetic abnormalities (HRCA). The ORR was 62% for 69 response-evaluable pts, including 42% with ≥very good partial response (VGPR). The median time to first response was 1.9 mos (IQR 1.0-2.4). After a median follow-up (mFU) of 7.6 mos, 6-mo PFS rate was 52.3% (95%CI 41.5-66%). The median duration of response has not been reached. In the cohort of early initiators (n=34), pts had more prior lines of therapy (LOT; median 8 vs 5, P=0.002) and higher proportion of prior BCMA therapy use (62% vs 23%; P=0.002) as compared to recent initiators treated after 3/31/23 (n=43). ORR was 67% and 59%, respectively (P=0.80; Table). Among all pts at data cut-off, 25 (32%) switched from weekly to every-other-week or monthly Tec after a median time of 3.1 mos from Tec initiation (95%CI 1.8-4.6) and based on achieving ≥PR and/or toxicity. At mFU of 5.3 mos since switching, 6-mo PFS rate was 94.1% (95%CI 83.6-100%). Conclusions: In this real-world study, Tec demonstrated comparable ORR to MajesTEC-1. Both early and recent Tec initiators had high baseline risk features. A higher proportion of early initiators had prior BCMA therapy and more LOTs, but both cohorts yielded consistently high treatment response rates. In pts who responded, schedule de-escalation was feasible with a high subsequent 6-mo PFS. Updated multicenter findings will be presented at the meeting. Table: see text