Background: Teclistamab is a B-cell maturation antigen (BCMA) targeting bispecific agent approved in 10/2022 for pts with relapsed refractory multiple myeloma (RRMM) based on the results of the MAJESTEC-1 study. This is the first report on the real-world safety and efficacy of teclistamab in pts with RRMM and highlights patterns of utilization and outcomes in pts, including those who would have been ineligible for enrollment on MAJESTEC-1. Methods: Twenty-two pts with RRMM who received teclistamab at the University of Kansas Health System as of 2/10/2023 had electronic medical records (EMR) reviewed retrospectively in collaboration with US Myeloma Innovations Research Collaborative (USMIRC). Baseline pt characteristics were outlined by descriptive analyses. Responses were evaluated using the International Myeloma Working group (IMWG) criteria. Adverse events were graded based on the CTCAE v5.0 criteria. Results: Pts included in the analysis had received a median of 6 prior LOT and 64% had extramedullary disease (EMD). All of the pts were triple class exposed and 91% were triple class refractory, 77%/59% were penta-class exposed/refractory, while 72% were refractory to prior BCMA directed therapy (BDT). Median follow up was 3.1 (1.7-4.1) months. The most common grade III/IV hematological toxicities were lymphopenia (95%), neutropenia (36%), leukopenia (36%), thrombocytopenia (32%) and anemia (9%). Cytokine release syndrome (CRS) was observed in 9 (41%) pts, all o which were grade I/II events, while immune effector cell-associated neurotoxicity syndrome (ICANS) was reported in 5 (23%) pts, with 2 (9%) pts having grade III events. The overall response rate was 50%, and was 56%,46% and 28% for pts who were BDT refractory, penta- refractory, or had EMD, respectively. Of those that did respond, responses tended to be deep (73% ≥ VGPR; 55% ≥ CR). No treatment related mortality was observed, although5 (23%) pts died due to disease progression during follow up. Conclusions: Our study demonstrates the efficacy of teclistamab in heavily pre-treated RRMM, including those who were penta-refractory, BDT refractory, or had EMD. Overall, teclistamab was well tolerated with no major safety events. Keywords: Plasma cell disorders, relapsed multiple myeloma, Penta-class refractory myeloma, BCMA directed therapy.