HPV-status stratifies exhaustion marker expression on CD8+ T cell in Head and Neck Squamous Cell Carcinoma
Kate Poropatich1, Joel Fontanarosa2, Suchitra Swaminathan3, Siqi Chen4, Sandeep Samant2, Bin Zhang4.
Department of Pathology1, Department of Otolaryngology2, Northwestern University
Feinberg School of Medicine Chicago, IL 60611, USA
Division of Rheumatology3, Department of Medicine-Division of Hematology/Oncology4,
Robert H Lurie Comprehensive Cancer Center, Department of Medicine-, Northwestern
University Feinberg School of Medicine, Chicago, IL 60611, USA
Background Information and Hypothesis: As of August 2016, HNSCC has become the third tumor type to earn FDA-approval for treatment with an anti-PD-1 immunotherapy. HPV-positive and –negative HNSCC are two distinct biologic processes and it is puzzling that patients from both groups on anti-PD1 agents appear to have comparable responses. This brings to attention the need for a reliable biomarker to better stratify immunotherapy administration in HNSCC patients. In this study we hypothesize that HPV-positive and –negative patients will stratify from one another based on intratumoral and peripheral levels of T cell exhaustion marker expression.
Methods: We performed flow cytometry analysis on 36 patients: 26 HNSCC cases (14 HPV-positive, 12 HPV-negative) and 10 healthy donor samples. Samples were tested from the primary site tumor (n= 20), metastatic cervical lymph nodes (n= 12), pathologically uninvolved cervical lymph nodes (n= 17) and peripheral blood (n=16). T cell lymphocytes were analyzed for expression levels of exhaustion markers PD-1, TIM-3 and CTLA-4.
Results: HPV-positive and -negative patients differed based on TIL expression levels of exhaustion markers on CD8+ T cells, not CD4+ T cells. Levels of CTLA-4+CD8+ TIL (p= 0.0013) and PBMC (p= 0.0344) were higher in HPV-negative patients, which was exclusive to T3/T4 patients. TIM-3+PD-1+ expression on CD8+ T cells levels was specific to the TME compared to peripheral tissue. TME PD-1+CD8+ T cell levels strongly correlated to a higher primary tumor stage (r2= 0.63, p= 0.0013), as did levels of PD-1+CTLA-4+ (r2= 0.48, p= 0.020) and PD-1+TIM-3+ (r2= 0.46, p= 0.027) CD8+ T cells.
Conclusions: For the first time, we demonstrate in a small patient cohort that HPV-negative patients with high T stage harbor elevated levels of peripherally circulating CTLA-4+CD8+ T cells. The logistical feasibility of testing HNSCC patients' peripheral blood for CD8+CTLA-4+ levels warrants clinical correlation with these patients' response to anti-PD-1 immunotherapy and consideration of adjunct anti-CTLA-4 therapy.