PROJECT SUMMARY The overarching goals of the Cancer Immunotherapy Program (CIM) are to enhance understanding of the interaction between the immune system and cancer and to develop novel, effective cancer immunotherapies. These goals will be achieved by (i) fostering collaborative research, (ii) developing and applying technologies to probe the immune system with high dimensionality, and (iii) enabling and supporting bench-to-bedside-to-bench translation to simultaneously deliver novel immunotherapies and discover biomarkers and mechanisms of resistance to immunotherapies. Fundamental research led by program members during the current funding period has enhanced understanding of T cell receptor (TCR):peptide interactions and identified unexpected systemic contributions to local immune responses in the tumor microenvironment (TME). Program members have (i) generated new technologies that greatly enhance the information gleaned from next-generation TCR sequencing; (ii) created the first platform capable of identifying targets of orphan TCRs; and (iii) developed multiplex ion beam imaging (MIBI), which enables unparalleled dimensionality of protein analysis in FFPE tissue. Translational research by CIM members (i) created “immune stimulating antibody conjugates” (ISACs) to induce antitumor immunity; (ii) defined fundamental properties of T cell exhaustion and created exhaustion-resistance and exhaustion-reversal platforms for adoptive cell therapy; (iii) discovered antigen density thresholds as a major regulator of CAR functionality and created approaches to tune such thresholds; (iv) translated rationally designed CAR-T cell therapies into clinical trials, which have provided benefit for patients with refractory cancers; and (v) created a robust reverse translation program that is identifying novel biomarkers of response and pathways of resistance to CAR therapeutics. Co-led by Crystal Mackall, MD, and Edgar Engleman, MD, the 27 members of the program represent 11 departments in the School of Medicine (SOM). Program members are major participants in a number of NCI R01s and P01s, two U54s, an R21, an R35, and one NIH T32 grant. Peer- reviewed funding consists of $4.3M from the NCI, $3.1M from other NIH, and $3.6M from other peer-reviewed sources, totaling $11.0M. Since 2015, 442 papers have been published, with 11% intra-programmatic, 42% inter- programmatic, and 94% multi-institutional collaborations. Major future efforts will seek to (i) define mechanisms of systemic immune tolerance that enable cancer metastasis; (ii) leverage advanced algorithms to interrogate large datasets of TCR sequences; (iii) expand the use of single-cell technologies to improve understanding of the immunobiology of cancer and predict/prevent toxicity of immunotherapies; (iv) develop next-generation cell therapy platforms and conduct clinical trials aimed at improving the efficacy of adoptive cell therapies; and (v) expand an already robust reverse translational program to...