Integrated drug profiling and CRISPR screening identify essential pathways for CAR T-cell cytotoxicity

Funding Information: The authors thank Laura Turunen, Jani Saarela, Katja Suomi, and Maria Nurmi of the High-Throughput Biomedicine Unit and the personnel of the Sequencing Laboratory at the Institute of Molecular Medicine Finland. The authors also thank Caroline Heckman, Sirpa Lepp?, and Olli Lohi for collaboration by providing the cell lines used in the study. The Biomedicum Helsinki Flow Cytometry Core Unit and the Biomedicum Virus Core are acknowledged for their services. The primary B-ALL samples were provided by the Finnish Hematology Registry and Clinical Biobank (FHRB). We thank all the patients for their generous participation. The FHRB biobank is supported by the Finnish Association of Hematology, Finnish Red Cross Blood Service, Institute for Molecular Medicine Finland, and participating hospitals in Finland. This study was supported by the Cancer Foundation Finland, the Sigrid Juselius Foundation, the Relander Foundation, state funding for university-level health research in Finland, and HiLife fellow funds from the University of Helsinki. O.D. was supported by grants from the Biomedicum Helsinki Foundation and the Finnish Medical Society. J. Koski was supported by grants from the Finnish Pediatric Cancer Foundation, the V?re Pediatric Research Foundation, the Cancer Foundation Finland, the Orion Research Foundation, and state funding for university-level health research in Finland. Funding Information: This study was supported by the Cancer Foundation Finland, the Sigrid Juselius Foundation, the Relander Foundation, state funding for university-level health research in Finland, and HiLife fellow funds from the University of Helsinki. O.D. was supported by grants from the Biomedicum Helsinki Foundation and the Finnish Medical Society. J. Koski was supported by grants from the Finnish Pediatric Cancer Foundation, the Väre Pediatric Research Foundation, the Cancer Foundation Finland, the Orion Research Foundation, and state funding for university-level health research in Finland. Funding Information: The authors thank Laura Turunen, Jani Saarela, Katja Suomi, and Maria Nurmi of the High-Throughput Biomedicine Unit and the personnel of the Sequencing Laboratory at the Institute of Molecular Medicine Finland. The authors also thank Caroline Heckman, Sirpa Leppä, and Olli Lohi for collaboration by providing the cell lines used in the study. The Biomedicum Helsinki Flow Cytometry Core Unit and the Biomedicum Virus Core are acknowledged for their services. The primary B-ALL samples were provided by the Finnish Hematology Registry and Clinical Biobank (FHRB). We thank all the patients for their generous participation. The FHRB biobank is supported by the Finnish Association of Hematology, Finnish Red Cross Blood Service, Institute for Molecular Medicine Finland, and participating hospitals in Finland. Publisher Copyright: © 2020 American Society of Hematology Chimeric antigen receptor (CAR) T-cell therapy has proven effective in relapsed and refractory B-cell malignancies, but resistance and relapses still occur. Better understanding of mechanisms influencing CAR T-cell cytotoxicity and the potential for modulation using small-molecule drugs could improve current immunotherapies. Here, we systematically investigated druggable mechanisms of CAR T-cell cytotoxicity using >500 small-molecule drugs and genome-scale CRISPR-Cas9 loss-of-function screens. We identified several tyrosine kinase inhibitors that inhibit CAR T-cell cytotoxicity by impairing T-cell signaling transcriptional activity. In contrast, the apoptotic modulator drugs SMAC mimetics sensitized B-cell acute lymphoblastic leukemia and diffuse large B-cell lymphoma cells to anti-CD19 CAR T cells. CRISPR screens identified death receptor signaling through FADD and TNFRSF10B (TRAIL-R2) as a key mediator of CAR T-cell cytotoxicity and elucidated the RIPK1-dependent mechanism of sensitization by SMAC mimetics.Death receptor expression varied across genetic subtypes of B-cell malignancies, suggesting a link between mechanisms of CAR T-cell cytotoxicity and cancer genetics. These results implicate death receptor signaling as an important mediator of cancer cell sensitivity to CAR T-cell cytotoxicity, with potential for pharmacological targeting to enhance cancer immunotherapy. The screening data provide a resource of immunomodulatory properties of cancer drugs and genetic mechanisms influencing CAR T-cell cytotoxicity. Key Points: • Survey of immunomodulatory effects of >500 drugs identifies SMAC mimetics as sensitizers to CAR T-cell cytotoxicity. • Genome-scale CRISPR screen reveals essentiality of death receptor signaling for CAR T-cell cytotoxicity.