Analyzing Real-World Infection Risk in Multiple Myeloma Patients Receiving Teclistamab

Background: Teclistamab is an anti-B-cell maturation antigen bispecific antibody used in relapsed, refractory multiple myeloma that induces durable responses but is associated with infectious complications. Real-world data characterizing infection risk remain limited. Methods: We conducted a single-center retrospective cohort study of relapsed/re fractory multiple myeloma patients treated with teclistamab from 1 January 2023 to 20 November 2023. The primary objective was to establish the incidence of infections after initiation of teclistamab. Secondary objectives included infection-related outcomes and identifying potential risk factors for infection. Results: 19 patients received teclistamab with a median age of 72 [IQR: 62–74] years and 73.7% had Karnofsky performance score < 80. A total of 11 (57.9%) patients developed 19 infections, with seven patients having multiple infections. There were five bacteremias, five other bacterial infections, seven respiratory viral infections, and 2 CMV reactivation events. Median time to first infection was 20 days (IQR: 9–87) and median grade of all infections was three (range: 1–5). Of the 19 documented infections, 15 (78.9%) were Grade ≥ 3. A total of 10 patients in the infection group and three in the non-infection group discontinued therapy permanently (p = 0.013). Conclusion: In this real-world cohort, infectious complications emerged early and frequently during teclistamab therapy and were a major driver of treatment interruption and permanent discontinuation. The clinical impact of infection extended beyond acute morbidity, often limiting continued access to an otherwise effective therapy in a heavily pretreated population. These findings highlight the need for proactive, individualized infection risk assessment and for standardized, evidence-informed approaches to infection monitoring, prophylaxis, and treatment modification during teclistamab therapy. Larger, multicenter studies will be essential to define strategies that balance infection risk with treatment durability in patients with limited therapeutic alternatives.