Evaluation of the relationship between PD-L1 expression and TIL levels on neoadjuvan chemotherapy response and survival in ovarian cancer patients who underwent interval debulking surgery

We retrospectively examined 45 patients with epithelial ovarian cancer who were admitted to Hacettepe University Faculty of Medicine hospitals between 2010-2018 and received neoadjuvan chemotherapy. The demographic and clinical features of the cases, information about the performed treatment and surgical procedures and progression-free survival (PFS) data were obtained from the hospital records. PD-L1 expression and CD8+ tumor infiltrating lymphocyte (TIL) levels were measured in the first biopsy of the tumor in which the patients were diagnosed. The association of these markers with PFS and chemotherapy response score (CRS) in interval debulking surgery performed after neoadjuvan 3 cycles of chemotherapy was investigated. The mean age of the patients was 61,60 9,9 years. The median follow-up was 19 months. Median progression-free survival was 18 months. Of 45 patients, 32 (71.1 %) were stage III and 13 (28.9 %) patients were stage IV. Recurrence was observed in 21 (46.7 %) patients in the follow-up. As a result of the evaluation of chemotherapy response score, CRS 1 (no response) was found in 5 (% 11,1) patients, CRS 2 (partial response) in 29 (% 64,4 ) patients, CRS 3 (complete response) in 11 ( % 24,4) patients. Low expression intraepithelial CD8+ levels were detected in 25 (% 55,6) patients and high expression intraepithelial CD8+ levels in 20 (% 44,4) patients. In the evaluation of stromal CD8+ level, 10 (% 22,2) patients had low expression and 35 (% 77,8) patients had high expression. No statistically significant relationship was found between high and low expression intraepithelial and stromal CD8+ levels and PFS. There was no relationship between intraepithelial and stromal CD8+ expression and chemotherapy response scoring. Expression of intraepithelial PD-L1 was found ≤ 1% (low expression) in 20 (% 44,4) patients. 1-10% (moderate expression) were observed in 15 (% 33,3) patients and ≥ 10% (high expression) in 10 (% 22,2) patients. Intraepithelial low expression PD-L1 group had 28 months of PFS, while medium expression group was 17 months and high expression group was 15 months (p=0,028). While 8 ( % 72.7) of 20 patients in the intraepithelial low expression PD-L1 group achieved CRS 3 (complete response), CRS 3 was found in 1 (% 9.1) of 10 high expressing patients (p = 0.005).While CRS 2 was obtained in 10 (% 34,5) and CRS 3 in 3 (% 27,3) of 18 patients with low expression stromal PDL1 levels, CRS 3 in 7 (% 63,6) and CRS 2 in 10 (% 34,5) of the 17 patients with medium expression‚ CRS 3 in 1 (% 9,1) and CRS 2 in 9 (% 31,0) of the 10 patients with high expression (p= 0,023). Chemotherapy response was significantly declined when PD-L1 levels were elevated. In conclusion, we found that intraepithelial and stromal PD-L1 expression levels in diagnostic biopsy in ovarian cancer can predict the chemotherapy response score in interval debulking surgery.