Case-control study of PD-1, PD-L1, and B7-H3 expression in human immunodeficiency virus infected (HIV+) and uninfected patients with head and neck cancers.

Abstract

e23194 Background: HIV+patients are typically excluded from immunotherapy trials but there are limited data on co-signaling molecule expression in these patients, including in head and neck squamous cell carcinoma (HNSCC). Methods: A case control study was conducted to evaluate tumor tissue sections for PD-L1, PD-1, and B7-H3 expression in HIV+HNSCC patients (n = 12) and HNSCC controls (n = 12). Cases and controls were matched for age at diagnosis, race, gender, TNM stage, and primary site. Smoking status, HIV RNA viral load (VL), and CD4 count were also recorded. Immunostained tumor sections were analyzed for percent of tumor cells expressing PD-L1 (PD-L1%) and B7-H3(B7-H3%) (Abcam), and percent of tumor infiltrating lymphocytes (TIL) expressing PD-1 (TIL-PD-1%) and PD-L1 (TIL-PD-L1%) (Abcam). Statistical analysis used the non-parametric Mann-Whitney test, chi-square test and Spearman’s rank correlation, Rs. Results: The 12 HIV+ HNSCC cases were predominantly male (67%), black race (67%) and cigarette smokers (100%), with a median age of 50.4 years, median viral load (VL) of 52399 copies/mL, median CD4 count (CD4) of 236cells/uL, predominantly locally advanced (75% Stage III/IVa/IVb), and oropharyngeal primary site (42%). Defining positive expression as > 5%, 42% of HIV+ HNSCC patients tumors were positive for PD-L1, 100% for B7-H3, and 92% had TILs that expressed PD-1 and PD-L1. HIV+ patients had significantly higher B7-H3% (Median 60% vs. 20%, p = 0.03) and TIL-PD-L1% (Median 15% vs. 10%, p = 0.045) compared to controls. There were no differences in PD-L1% or TIL-PD-1%. In HIV+ cases, increased VL correlated with increased TIL-PD-1% (Rs = 0.73, p = 0.011) and increased CD4 count correlated with increased tumor PD-L1% (Rs = 0.62, p = 0.04). There were no other significant correlations between CD4 count or VL and co-signaling molecule expression. Conclusions: HIV+ HNSCC patients had significantly higher tumor B7-H3 and TIL PD-L1 expression, with similar tumor PD-L1 and TIL PD-1 expression, compared to HIV negative HNSCC control patients. These findings support inclusion of HIV+ HNSCC patients in immunotherapy trials with checkpoint inhibitors.