Identification of an excellent prognosis subset of human papillomavirus-associated oropharyngeal cancer patients by quantification of intratumoral CD103+ immune cell abundance

Background: Accurate prognostic stratification of human papillomavirus-associated oropharyngeal cancers (HPV+OPSCC) is required to identify patients potentially suitable for treatment deintensification. We evaluated the prognostic significance of CD103, a surface marker associated with tissue-resident memory T cells (T(RM)s), in two independent cohorts of patients with HPV+OPSCC. Patients and methods: The abundance and distribution of CD103(+) immune cells were quantified using immunohistochemistry in a cohort of 189 HPV+OPSCC patients treated with curative intent and correlated with outcome. Findings were then validated in an independent cohort comprising 177 HPV+OPSCCs using univariable and multivariable analysis. Intratumoral CD103(+) immune cells were characterized by multispectral fluorescence immunohistochemistry and gene expression analysis. Results: High intratumoral abundance of CD103(+) immune cells using a >= 30% cut-off was found in 19.8% of tumors in the training cohort of HPV+OPSCC patients and associated with excellent prognosis for overall survival (OS) with adjusted hazard ratio (HR) of 0.13 [95% confidence interval (CI) 0.02-0.94, P = 0.004]. In the independent cohort of HPV+OPSCCs, 20.4% had high intratumoral CD103(+) abundance and an adjusted HR for OS of 0.16 (95% CI 0.02-1.22, P = 0.02). Five year OS of patients with high intratumoral CD103 was 100% across both cohorts. The C-statistic for the multivariate prognostic model with stage and age was significantly improved in both cohorts with the addition of intratumoral CD103(+) cell abundance. On the basis of spatial location, co-expression of CD8 and CD69, and gene expression profiles, intratumoral CD103(+) cells were consistent with T(RM)s. Conclusion: Quantification of intratumoral CD103(+) immune cell abundance provides prognostic information beyond that provided by clinical parameters such as TNM-staging, identifying a population of low risk HPV+OPSCC patients who are good candidates for trials of deintensification strategies.