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

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.