Single institution experience on papillary renal cell carcinoma PD-1/PD-L1 expression, pathological analysis, and outcomes after nephrectomy.

Abstract

e16048 Background: The PD-1/PD-L1 pathway plays an important role in tumor growth and tolerance among renal cancer cells. Renal cell carcinoma (RCC) consists of several different histological subtypes, including clear cell and non-clear cell varieties. Papillary RCC is the most common non-clear cell type and accounts for almost 13% of RCC cases. Our center has a large volume of papillary RCC patients treated by nephrectomy or with systemic therapy. This retrospective study examines pathological criteria, outcomes, and PD-1/PD-L1 expression in a defined cohort. Methods: Institutional review board (IRB) approval was obtained to access and retrospectively review clinical and pathological data of patients that presented with papillary RCC and had a partial or radial nephrectomy during a 1 year duration at our institution. We collected data on survival, systemic treatments, and pathological staging. Tumor samples from the patients were also stained and analyzed for PD-1 and PD-L1 expression. Results: 31 patients were identified with papillary histology after nephrectomy. 45% (14/31) of the patients underwent a radial nephrectomy while 55% (17/31) underwent a partial nephrectomy. Of these 31 patients, 23 had tumor slides available for staining and review. 65% (15/23) of the tumor samples were type 1 papillary RCC, and 35% (8/23) were type 2. PD-L1 was expressed in 13% (3/23) of the cases and PD-1 was expressed in 52% (12/23) of the cases. 71% of the patients were pT1 and 84% of the patients were alive at 5 years. Only 1/31 patients required use of systemic therapy. 74% (17/23) of patients were African American. Conclusions: Patients undergoing nephrectomy for papillary RCC at our institution commonly had small primary tumors with excellent survival. 46% of the tumors expressed PD-1, whereas only 12% expressed PD-L1. Trials that study the inhibition of the PD-1/ PD-L1 pathway may be helpful in strategies for treating both localized and metastatic papillary RCC. Further genomic and pathological examination of additional samples is currently underway.