PD‐L1 and Ki‐67 Expression Before and After Neoadjuvant Chemotherapy in Muscle‐Invasive Bladder Cancer

ABSTRACT Objective Programmed cell death ligand 1 (PD‐L1) expression is considered a poor prognostic factor in patients with muscle‐invasive bladder cancer (MIBC). However, the data regarding the change in PD‐L1 expression before and after neoadjuvant chemotherapy (NAC) are limited. We aimed to investigate the longitudinal association between programmed death‐ligand 1 (PD‐L1) and Ki‐67 expression before and after NAC in muscle‐invasive bladder cancer (MIBC). Methods We retrospectively analyzed 191 patients with MIBC who underwent platinum‐based NAC followed by radical cystectomy (RC) between June 2010 and March 2022. We excluded ypT0‐1 cases because of the difficulty of evaluating PD‐L1 and Ki‐67 by immunostaining. Finally, we selected 104 patients with matched specimens from transurethral resection of bladder tumor (TURBT) and residual invasive disease in RC. We examined the relationship between PD‐L1 expression and Ki‐67 labeling index in TURBT and RC specimens. Additionally, we investigated the differential expression of 39 subtype‐related genes before and after NAC. Results Among 104 patients who underwent NAC, the number of PD‐L1‐positive patients significantly increased from 16 (15.4%) in the TURBT specimens to 30 (28.8%) in the RC specimens. The median Ki‐67 labeling index significantly decreased from 30.6% in the TURBT specimens to 9.9% in the RC specimens. The correlation between treatment effects and changes in gene expression was challenging to identify. Conclusions A significant effect of NAC on PD‐L1 expression and Ki‐67 labeling index was observed in patients with MIBC. However, the impact of changes in gene expression on prognosis needs further study.