PD-L1 expression in bladder primary in situ urothelial carcinoma: evaluation in BCG-unresponsive patients and BCG responders

Carcinoma in situ (CIS) is believed to be a precursor of muscle-invasive carcinomas that may arise from these flat high-grade, superficial urothelial lesions. CIS accounts for approximately 10% of all bladder tumors. Therapeutic options for urothelial CIS are limited, and in order to inhibit disease progression and recurrence, current guidelines recommend transurethral resection (TURBT) followed by intravesical administration of Bacillus of Calmette-Guerin (BCG). Approximately 30-40% of patients fail the BCG therapy with recurrence and progression of disease. In the present study, we examined the expression of PD-L1 both in neoplastic epithelial cells and in stromal inflammatory cells in patients with diagnosis of CIS primary responders and not responders to BCG therapy, in order to verify if the PD-L1 expression could identify patients resistant to BCG treatment. Moreover, we analyzed on the same cases the immunoreactivities of anti-PD-L1 MoAbs such as SP263, C23, and SP142. Our results have showed that PD-L1 expression in tumor cells and in immune cell compartment is higher in BCG-unresponsive group than in BCG responders, but only the PD-L1 22C3 expression in tumor cells seems to be associated with recurrence of disease (p = 0.035; OR 0.1204; CI 95% from 0.0147 to 1.023). Hence, our data suggest that the PD-L1 22C3 expression could help to identify CIS that fail the BCG therapy, supporting the hypothesis that enhanced levels of intratumoral PD-L1 22C3 expressed by the tumor cells may explain the failure of BCG immunotherapy.