P-256: Initial Report of a Single Institution Experience with Teclistamab for Relapsed or Refractory Multiple Myeloma Including Prior BCMA

Introduction: Despite the rapidly evolving treatment armamentarium, multiple myeloma (MM), remains an incurable cancer. Teclistamab (TEC) is the first CD3 x BCMA, T-cell redirecting bispecific antibody indicated for the treatment of adult patients (pts) with relapsed or refractory MM (RRMM). Unfortunately, pts who received TEC in clinical trials (CT) are not representative of the real-world population. Here, we describe our initial experience among RRMM pts who received TEC at our institution from Dec 2022 to May 2023.

Methods: This retrospective study included 26 pts with a confirmed diagnosis of MM who received TEC outside of a CT. Descriptive analyses were performed for baseline characteristics. The 2016 IMWG criteria were used to assess disease response and/or refractoriness to prior LOT. All pts were admitted to the hospital for TEC step-up doses and mandatory 48 hours of observation post-administration. All pts were given acyclovir and sulfamethoxazole-trimethoprim prophylaxis, or an alternative.

Results: The median age of our cohort was 64 (range 45-75) yrs; 54% were females and 73% were Caucasian. The median number of prior LOT were seven (range 4-17), including nine (38%) pts with previous anti-BCMA (idecabtagene vicleucel) and one belantamab. One hundred percent and 92% of pts had the triple and penta-refractory disease, respectively. Ten (38%) pts had prior HSCT. Twenty-two (85%) pts developed cytokine release syndrome (CRS), which in most cases was mild (95% grade 1-2, 5% grade 3, 0% grade 4-5); of these 22 pts, 18 (82%) required tocilizumab (median number of total doses was one) and eight (36%) steroids. The most common CRS presentation was fever (91%), followed by hypoxia (9%) and hypotension (4.5%). TEC led to immune effector cell-associated neurotoxicity syndrome (ICANS) in five (19%) pts during the step-up period (100% grade 1-2); of them, 4 had CRS and 3 received steroids. Only seven pts experienced infections during the step-up period, of whom two had severe infections requiring intravenous (IV) therapies (COVID-19 infection treated with remdesivir, septic arthritis treated with IV antibiotics). For efficacy analysis, one pt was excluded due to recurrent ICANS with following doses mandating TEC discontinuation. After a median follow-up of 2.5 months, the best responses achieved were: four (16%) pts achieved complete response, five (20%) very good partial response, six (24%) partial response, four (16%) had stable disease, while three (12%) progressed and three (12%) died without achieving any response. Eventually, six (24%) pts progressed and four (16%) died.

Conclusions: TEC is a promising therapy for pts with RRMM including those with prior BCMA exposure. Cytopenias and infections were reported but not significantly different from prior studies. No new safety signals were identified. These initial findings support the safety and efficacy of TEC in BCMA naïve and exposed pts and early anti-IL6 therapy to prevent escalation of CRS. Analysis of long-term outcomes is ongoing.