ENAapplication/xmlftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/061/SRR26622261/SRR26622261.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/058/SRR26622258/SRR26622258.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/054/SRR26622254/SRR26622254.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/065/SRR26622265/SRR26622265.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/062/SRR26622262/SRR26622262.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/064/SRR26622264/SRR26622264.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/063/SRR26622263/SRR26622263.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/059/SRR26622259/SRR26622259.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/056/SRR26622256/SRR26622256.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/057/SRR26622257/SRR26622257.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/060/SRR26622260/SRR26622260.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR266/055/SRR26622255/SRR26622255.fastq.gzprimaryOK200GenomicsThe Marcel van den Brink Lab, Department of Immunology, Memorial Sloan Kettering Cancer Centerhttps://www.ebi.ac.uk/ena/browser/view/PRJNA1034126Mus musculusxref:PubMed:38579288Multiple myeloma is a plasma cell malignancy that is currently incurable with conventional therapies. Following the success of CD19-targeted chimeric antigen receptor (CAR) T-cells in leukemia and lymphoma, CAR T-cells targeting B-cell maturation antigen (BCMA) more recently demonstrated impressive activity in relapsed and refractory myeloma patients. However, BCMA-directed therapy can fail due to low expression of BCMA on myeloma cells, suggesting that novel approaches to better address antigen-low disease may improve patient outcomes. We hypothesized that engineered secretion of the pro-inflammatory cytokine interleukin-18 (IL-18) and multi-antigen targeting could improve CAR T-cell activity against BCMA-low myeloma. In a syngeneic murine model of myeloma, CAR T-cells targeting the myeloma-associated antigens BCMA and B-cell activating factor (BAFF-R) failed to eliminate myeloma when these antigens were weakly expressed. In contrast, IL-18-secreting CAR T-cells targeting these antigens promoted myeloma clearance. IL-18-secreting CAR T-cells developed an effector-like T-cell phenotype, promoted interferon-gamma production, reprogrammed the myeloma bone marrow microenvironment through type I and II interferon signaling, and utilized macrophages to mediate anti-myeloma activity. Simultaneous targeting of weakly expressed BCMA and BAFF-R with dual-CAR T-cells enhanced T-cell:target cell avidity, increased overall CAR signal strength, and stimulated anti-myeloma activity. Dual-antigen targeting augmented CAR T-cell secretion of engineered IL-18 and facilitated elimination of larger myeloma burdens in vivo. Our results demonstrate that combination of engineered IL-18 secretion and multi-antigen targeting can eliminate myeloma with weak antigen expression through distinct mechanisms. Overall design: scRNA and CITE-seq analysis of CD45+ mouse bone marrow following treatment with CAR T cells engineered to secrete IL-18ENAfalseIL-18-secreting multi-antigen targeting CAR T-cells eliminate antigen-low myeloma in an immunocompetent mouse model [in vivo]IL-18-secreting multi-antigen targeting CAR T-cells eliminate antigen-low myeloma in an immunocompetent mouse model [in vivo]2025-09-242024-05-17PRJNA1034126GSE2466821009038579288