PROJECT SUMMARY − PROJECT 1 In recurrent and metastatic head and neck squamous cell carcinoma (R/M HNSCC), immune checkpoint blockade has changed the standard of care, with trials from HN SPORE PI Dr. Robert Ferris and co-I (Project 2) Dr. Barbara Burtness pioneering the use of anti-PD-1 in this setting. Unfortunately, only a minority of patients benefit, due to resistance to anti-PD-1 therapy, pointing to an urgent need to better understand the tumor microenvironment. With HN SPORE support, first through a Developmental Research Program award and later following elevation to Continuing Project 1, we have identified a connection between tumor metabolism, hypoxia and T cell dysfunction that may be partially driving resistance to anti-PD-1 (Zandberg, et al, ASCO 2020). To further investigate this question, we are proposing to conduct two newly designed, novel therapeutic clinical trials within Project 1, in R/M HNSCC naïve to anti-PD-1 (HCC 18-190/NCT04114136) or progressed on anti-PD-1 (HCC 18-156/NCT04326257). The former is a trial of metabolic modulators and anti- PD1, the latter a trial of anti-PD-1 combined with either anti-CTLA4 or anti-LAG3. Utilizing these trials and pre- clinical models of HNSCC, we will examine the following questions. First, what is the relationship between anti-PD-1 resistance, tumor metabolism and hypoxia in HNSCC? With the assistance of Core B, we will address this question via multiplexed tissue analysis in R/M HNSCC samples from our clinical trials as well as radiomics-based approaches of determining tumor hypoxia. Second, does hypoxia promote resistance to combinatorial immunotherapy in HNSCC? We will test how hypoxia may impede immunotherapy with nivolumab plus relatlimab (anti-LAG3), or ipilimumab (anti-CTLA4) in R/M HNSCC patients who have progressed on anti-PD-1, evaluating tissue before and after therapy. Third, can metabolically targeted therapy be combined with anti-PD-1 to overcome anti-PD1 resistance in HNSCC? We will evaluate tumor samples obtained before and after treatment with anti-PD-1 plus either metformin or rosiglitazone and determine changes in tumor metabolism and hypoxia. We will also test combinatorial immunotherapy (as in Aim 2) with metabolic modulation in pre-clinical HNSCC models rendered anti-PD1 resistant. Our trial of metabolic inhibitors combined with anti-PD1 therapy, if positive, will directly lead to larger scale clinical studies, opening up an entirely novel avenue of combinatorial immunotherapy; while the project as a whole will also provide a platform for developing future personalized immunotherapy trials by adding metabolic analysis and/or modulation as a component.