Clinical interest of PD-L1 immuno-histochemistry expression as a predictive factor of Bacillus Calmette Guerin (BCG) efficacy in refractory high-risk non-muscle-invasive bladder cancer (NMIBC).

To assess PD-L1 expression in tumor (TC) and tumor infiltrating immune cells (IC) as a predictive factor of BCG therapy failure in high-risk NMIBC.

Patients treated with complete resection followed by bladder BCG instillation for high-risk NMIBC were included. Early recurrence (ER) was defined as tumor recurrence after BCG induction course. The association between ER and immuno-histochemistry PD-L1 (E1L3N clone) expression by tumors cells (TC) and tumor infiltrating immune cells (IC) was investigated using an exact Fisher test variant.

A total of 186 patients were included, of whom 38 (20.4%) were ER, 35 (18.8%) were positive for TC PD-L1 expression and 60 (32.3%) were positive for IC PD-L1. ER was not significantly (p = 0.97) more frequent in the TC PD-L1 ≥ 1% group (n = 7, 20.0%) than in the TC PD-L1-negative group (n = 31, 20.5%). Patients with IC PD-L1 negative had ER in 15 (19.2%) cases and patients with IC PD-L1 ≥ 1% had ER in 23 (21.3%) cases. PD-L1-positive expression for IC (threshold > 1%) was correlated with immune infiltrate density (95.2% dense immune infiltrate vs 47.2% low immune infiltrate, p < 0.05), with increased expression of PD-L1 by IC after BCG therapy (p = 0.006).

No association was observed between immuno-histochemistry PD-L1 positivity and ER after BCG therapy. Nevertheless, the relationship between immune infiltrate and PD-L1 positivity confirmed the interest of assessing the immune infiltrate density to define tumor's profile.

World journal of urology. 2019 Sep 05 [Epub ahead of print]

Clara Delcourt, Pierre Gemival, François Xavier Nouhaud, Françoise Gobet, Andre Gillibert, Sophie Ferlicot, Jean Christophe Sabourin, Jacques Irani, Christian Pfister

Department of Urology, Charles Nicolle Rouen University Hospital, 1 rue de Germont, 76031, Rouen Cedex, France., Department of Pathology, Rouen University Hospital, Rouen, France., Department of Biostatistics, Rouen University Hospital, Rouen, France., Department of Pathology, Kremlin Bicêtre Hospital, Paris, France., Department of Urology, Kremlin Bicêtre Hospital, Paris, France., Department of Urology, Charles Nicolle Rouen University Hospital, 1 rue de Germont, 76031, Rouen Cedex, France. .