Towards mapping immune responses of nasopharyngeal carcinoma in Saudi Arabian patients, single institution experience.

Abstract

e17541 Background: The prevalence of Nasopharyngeal Carcinoma (NPC) is higher in Saudi Arabia compared to western countries. Genetic susceptibility and/or environmental factors (like infection with Epstein-Barr virus) contribute to the development of this tumor. There is a lack of information on the expression of markers related to the immune response in Saudi NPC patients. Methods: Here we report on profiling of two cohorts of NPC cases from patients treated at King Faisal specialist hospital & Research cneter (KFSH&RC) using the most relevant immune markers. The first cohort included 54 patients with local NPC while the other cohort included 25 cases of metastatic NPC at presentation. Immunostaining was done using Ventana benchmark fully automated system. Two anatomical pathologists (SM & HK) scored the NPC cases for CD3+ infiltrating lymphocytes (TIL), and their sub-fractions co-staining for CD8, FOXP3 and/or PD-1. On the other hand, PDL1 expression was assessed on tumor cells. Statistical analysis was done using JUMP Pro 13 software. Results: There was an induction of membranous PDL1 expression on tumor cells of 70 and 64% in local and metastatic cases respectively. Interestingly, there was a significant number of cases with cytoplasmic expression of PDL1 (46% of local and 36% metastatic cases) in addition to the membranous expression. PD-1 was over-expressed (on ≥ 10% of TIL) in 52% and 68% of local and metastatic cases respectively. FOXP3+ T-cells were abundant in the tumor tissues as 78% of cases had ≥10% of their infiltrating CD3+ T-cells co-staining for nuclear FOXP3. Finally, CD8 were an abundant fraction of total CD3+ infiltrating T-cells in more than 60% and 78% of Local and metastatic cohorts respectively. Correlation of the above studied immune markers with patients clinical outcome shows statistically significant correlation (p = 0.008) between low CD3+ T-cell infiltration in tumor tissues at diagnosis and the relapse of the disease. Conclusions: PDL1 is upregulated, FOXP3+ T-regs are abundant, only the low intensity of CD3+ lymphocytes could predict for higher chances of relapse. These preliminary profiling data provide the basis for future immunotherapy trials for NPC in KFSH&RC