W142 - Impact of the Gastrointestinal Microbiota on the Immune Population Obtained During the Apheresis of Patients Undergoing CAR-T Cell Therapy for Multiple Myeloma

Aina Oliver-Caldés – Hematology Department, ICMHO, Hospital Clínic de Barcelona, Barcelona, Spain.; Marta Español-Rego – Immunology Department, CDB, Hospital Clínic de Barcelona, Barcelona, Spain.; Neus Martínez-Micaelo – Biosfer Teslab, Reus, Tarragona, Spain.; Roberto Martínez – Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clinic de Barcelona, Barcelona, Spain.; Elisa rubio – Microbiology Department, Hospital Clínic de Barcelona, Barcelona, Spain.; andrea Vergara – Microbiology Department, Hospital Clínic de Barcelona, Barcelona, Spain.; Oscar Yanes – Department of Electronic Engineering,Universitat Rovira i Virgili, Reus, Tarragona, Spain.; Núria Amigó – Biosfer Teslab, Reus, Tarragona, Spain.; Daniel Benítez-Ribas – Immunology Department, CDB, Hospital Clínic de Barcelona, Barcelona, Spain.; Climent Casals – Microbiology Department, Hospital Clínic de Barcelona, Barcelona, Spain.; Mercedes Montoro – Hematology Department, ICMHO, Hospital Clínic de Barcelona, Barcelona, Spain.; V González-Calle – Hospital Universitario de Salamanca, Instituto de Investigacion Biomedica de Salamanca (IBSAL), Centro de Investigacion del Cancer (IBMCC-USAL, CSIC), Salamanca, Spain.; Valentin Cabañas – Hospital Clinico Universitario Virgen de la Arrixaca, Murcia, Spain.; Beatriz Martin-Antonio – Fundació Clinic per a la Recerca Biomèdica (FCRB). Hospital Clínic de Barcelona, Barcelona, Spain.; Lorena Pérez-Amill – Fundació Clinic per a la Recerca Biomèdica (FCRB). Hospital Clínic de Barcelona, Barcelona, Spain.; JL Reguera – Hospital Universitario Virgen del Rocio, Instituto de Biomedicina de Sevilla (IBIS/CSIC/CIBERONC), University of Sevilla, Sevilla, Spain.; Paula Rodríguez-Otero – Clínica Universidad de Navarra, Centro de Investigacion Medica Aplicada (CIMA), IDISNA, CIBERONC Pamplona, Pamplona, Spain.; JM Moraleda – Hospital Clinico Universitario Virgen de la Arrixaca, Murcia, Spain.; Mariona Pascal – Immunology Department, CDB, Hospital Clínic de Barcelona, Barcelona, Spain.; Álvaro Urbano-Ispizua – Hematology Department, ICMHO, Hospital Clínic de Barcelona, Barcelona, Spain.; MV Mateos – ospital Universitario de Salamanca, Instituto de Investigacion Biomedica de Salamanca (IBSAL), Centro de Investigacion del Cancer (IBMCC-USAL, CSIC), Salamanca, Spain.; Carlos Fernández de Larrea – Hematology Department, ICMHO, Hospital Clínic de Barcelona, Barcelona, Spain.; Manel Juan – Immunology Department, CDB, Hospital Clínic de Barcelona, Barcelona, Spain.

Abstract Text: CAR-T cell therapy shows promising results in hematologic malignancies but is curative for only a fraction of patients, emphasizing the need for strategies to improve outcomes in non-responsive cases. This study aims to understand if the composition of the gastrointestinal microbiota impacts the immune population obtained during the apheresis of patients undergoing BCMA-directed CART (Clinical trial NCT04309981) therapy for multiple myeloma and the characteristics of the final CAR T-cell product infused. Twenty-seven patients were included, and microbiota composition was analyzed by amplifying and sequencing the V3-V4 region of the 16S rRNA; sequence reads were processed by QIIME2. A panel of 35 stool metabolites was assessed using nuclear magnetic resonance, and comprehensive clinical and CAR-T production data were collected. We investigated correlations between CD4+ immune subsets at the apheresis stage and their gut microbiota composition, as well as corresponding metagenomic and metabolomic profiles. Memory repertoire analysis uncovered correlations between CD4+ naïve, CD4+ central memory, and effector memory cells with bacterial families and metabolites. Notably, the Actinomycetaceae family and succinate emerged as independent predictive markers for CD4+ central memory and effector memory levels in the CAR T-cell infusion product, influencing the persistence of CAR T-cells post-infusion. Phenotypic, metabolite, and functional characterization of in vitro expanded CAR T-cells supplemented with succinate validated clinical results. This study establishes a correlation between the gastrointestinal microbiota composition and the immune population characteristics during apheresis and the final infusion product in BCMA-directed CAR-T therapy for multiple myeloma patients.