The Effect of Stem Cell Infusion on Immune Effector Cell Associated Hematotoxicity with BCMA CAR T in Multiple Myeloma

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.758-758
• Main Authors: Patwari, Anannya, Patel, Tanvi H., Bachu, Ramya, Esselmann, Jean, Rein, Lisa, Szabo, Aniko, Janardan, Abhishek, Bhatlapenumarthi, Vineel, Annyapu, Evanka, Skoog, Catherine E., Goff, Areyl, Al Hadidi, Samer, Venniyil Radhakrishnan, Sabarinath, Thanendrarajan, Sharmilan, Zangari, Maurizio, van Rhee, Frits, Dhakal, Binod, D'Souza, Anita, Mohan, Meera, Schinke, Carolina
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-186697

Introduction: In recent pivotal clinical trials and real-world studies of patients undergoing BCMA CAR-therapy for multiple myeloma (MM), a significant percentage have exhibited persistent Immune Effector Cell Associated Hematotoxicity (ICAHT). The resulting, sometimes profound and long lasting cytopenias, are associated with increased morbidity, such as high rates of infections and bleeding and complicate further anti-MM therapy once the patient relapses post CAR-T cell therapy. While growth factor support is widely applied in patients with ICAHT, the effects are usually short lived. Consequently, the use of CD34 selected stem cell boost in ICAHT as a more permanent solution has been described, however studies have been limited by small patient numbers and short follow up. Herein, we report on our multi-institutional experience at ICAHT in patients who received autologous BCMA CAR T therapy both in commercial and clinical trial settings. Methods: We included recipients of autologous BCMA CAR T therapy at 2 large academic centers between 2020 and 2023. For this study, neutropenia was defined as an absolute neutrophil count (ANC) of ≤ 1000, thrombocytopenia as platelet counts ≤ 70,000 and anemia as hemoglobin ≤9 g/dL. ICAHT was characterized by the presence of any of these hematological abnormalities. The variables were assessed at 21 days, 3 months, and 6 months post CAR-T infusion. Median follow up time was 23 months. Results : A total of 108 patients received BCMA CAR T therapy, 42 (39%) were treated on a clinical trial, 52 (48%) received commercial Idecabtagene vicleucel and 14/108 (13%) commercial Ciltacabtagene autoleucel. Baseline characteristics of the whole patient cohort are shown in table 1. The median age was 68 (range 57-69) years, with 63/107 (60%) being male. About 11% (n=12) patients were Black. 97/108 (90%) received at least one prior ASCT and the median prior lines of therapy was 5 (range 4-6). At D+21, ICAHT was observed in 68% (n=69/102) of patients, which reduced to 35% (n=30/86) and 27% (n=21/78) at the 3-month and 6-month assessments, respectively. Risk factors for ICAHT were the following: history of a prior ASCT, higher number of prior lines of therapy, a decreased platelet count prior to lymphodepletion and history of ICANS, which interestingly occurred in 11/69 (16%) patients who developed ICAHT but was not seen in those without ICAHT. About 97%(n=67/69) of patients with ICAHT had stem cells in storage and 26% (n=17/69) received a