Functional HPV16-specific tumor-infiltrating T cells express PD-1 but not Tim-3 in oropharyngeal cancer microenvironment
Kamila Hladíková1,2,*, Simona Partlová1,*, Vladimír Koucký1,3, Jan Bouček3,4, Michal Zábrodský3, Michael J. Halaška5, Ruth Tachezy6,7, Marek Grega8, Radek Špíšek1,2, Anna Fialová1
1Sotio, Prague, Czech Republic; 2Department of Immunology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czech Republic; 3Department of Otorhinolaryngology and Head and Neck Surgery, 1st Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic; 4Institute of Microbiology ASCR, v.v.i., Prague, Czech Republic; 5Department of Gynecology and Obstetrics, 3rd Faculty of Medicine and University Hospital Královské Vinohrady, Prague, Czech Republic; 6Department of Experimental Virology, Institute of Hematology and Blood Transfusion, Prague, Czech Republic; 7Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Prague, Czech Republic; 8Department of Pathology and Molecular Medicine, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic
Human papillomavirus (HPV) type 16 infection is recently considered to be one of the most significant risk factors, particularly for oropharyngeal squamous cell carcinoma (OPC) and the incidence of HPV-associated OPC is still increasing over the past two decades. Patients with HPV-positive OPC are associated with significantly better prognosis than patients with HPV-negative squamous cell carcinomas of the head and neck. Whereas tumor cells constitutively express highly immunogenic HPV16 E6 and E7 oncoproteins, HPV-specific T cell immunity may contribute to the better prognosis of patients with HPV-induced tumors. In this study we analyzed the frequency, phenotype and function of HPV16 E6/E7-specific tumor-infiltrating T cells (TILs) in patients with OPC and evaluated the effect of anti-PD1 mAb (nivolumab), soluble Tim-3 (sTim-3) and homeostatic in vitro expansion on these characteristics. We show the presence of HPV16-specific tumor-infiltrating T cells in 73% of HPV-positive oropharyngeal tumors characterized by production of IFNγ upon E6/E7 peptide pool stimulation. These HPV16-specific CD8+ TILs predominantly expressed PD-1 but not Tim-3, identifying Tim-3 rather than PD-1 as a marker of T cell dysfunction. Specific IFNγ production was further enhanced with using combination of nivolumab plus sTim-3, in comparison to PD-1 blockade alone. Our data suggest that complementary treatment combining anti-PD-1 blockade and/or blockade of other inhibitory pathways such as those of Tim-3 might substantially increase HPV16-directed therapeutic vaccines.