Tumor infiltrating lymphocytes (TIL) assessment in muscle invasive bladder cancer (MIBC) patients treated with cisplatin-based neoadjuvant chemotherapy (NAC) and surgery.

Abstract

547 Background: Cisplatin-based NAC followed by surgery is the gold standard treatment of non-metastatic MIBC. However, predictive biomarkers have not been established yet. Here, we addressed the relevance of TILs for NAC response and prognosis in MIBC patients (pts). Methods: We conducted a single center, retrospective cohort analysis of consecutive MIBC pts treated with cisplatin-based NAC followed by surgery. Pts with pathological complete response (pCR; ypT0/isN0) were grouped as responders, pts with pathological residual disease as non responders. TIL stromal count were assessed pre- and post-NAC. Next Generation Sequencing of selected genes was performed on pre-NAC samples. We catalogued the 3-years(y) relapse free rate and 3-y overall survival rate (OS, Kaplan Meier) for the overall cohort and by subgroups. Results: Of the 25 pts who received cisplatin-gemcitabine NAC, a total of 14 (56%) pts achieved a pCR and 11 (44%) had residual disease. NAC was discontinued in 17 (65%) after completing treatment; and in 8 (32%) pts after 2 cycles due to toxicity. Median follow-up was 54.2 months(mos). At baseline, median TIL count was 60% in the overall cohort. Numerically higher TIL count was observed among responders (80%) compared to non-responders (50%) ( p=0.22). Median TIL count post-NAC in residual samples was 40%, not significantly different to matched pre-NAC samples ( p=0.93). Overall, 3-y relapse free rate was 74.7% (95%CI 51.7-87.9); 3-y OS rate was 79.6% (95%CI 57.6-91) with 6 deaths of which 4 were related to metastatic disease. Table reports subset analyses. Most frequently altered genes were PIK3CA and TP53 in the overall cohort (each 20%) and in the responders subgroup (each 29%). Conclusions: In our study, pts who achieved pCR had numerically greater TIL infiltrate in baseline samples and pCR was associated with reduced risk of recurrence. TILs did not increase in residual tumors after NAC. The independent predictive value of TILs warrants assessment in large cohorts.[Table: see text]