PD-L1 EXPRESSION IS RARE IN PROSTATE CANCER AND DOES NOT CORRELATE WITH PTEN LOSS
Programmed cell-death ligand 1 (PD-L1) is an important target for immunotherapy in several malignancies with significant improvement in clinical outcomes have been achieved with anti-PD-L1 checkpoint inhibitors. PD-L1 expression may be regulated by oncogene expression as immunologic scape mechanism. Loss of the tumor suppressor phosphatase and tensin homolog (PTEN) has been associated with enhanced PD-L1 expression in glioblastoma, breast and pancreatic cancers. In prostate cancer (PCa), PTEN loss is observed in approximately 18-42% of cases and is associated with poor prognosis.
We aimed to investigate PD-L1 expression in radical prostatectomy specimens and its correlation with PTEN loss by immunohistochemistry (IHC).
We examined PTEN loss and PD-L1 expression (in any percentage of tumor cells, with membranous staining) in 101 tumor specimens from radical prostatectomy. PD-L1 expression was evaluated by IHC with 22C3 PharmDx assay (Dako). PTEN loss was assessed using anti-PTEN antibody Clone SP218 (Roche). The data was correlated with clinicopathological characteristics.
The median age of subjects was 71 years (range 51-98). Thirty-one (26%) showed Gleason score ≤ 6, 50 (42%) Gleason score 7 and 38 (32%) Gleason score ≥ 8. PTEN loss was identified in 37% (37/101) of samples, while PD-L1 was expressed in just 3% (3/99). All samples positive for PD-L1 showed loss of PTEN.
PD-L1 expression was observed in only 3% of prostate cancer specimens and all of them had loss of PTEN. Majority of tumors with PTEN loss do not express PD-L1.
PD-L1, PTEN, Prostate cancer, Biomarkers
Laboratorio Argos Patologia - Ceara - Brasil, Laboratorio Argos Patologia - Ceara - Brasil
VLADMIR PINHEIRO OLIVEIRA, ANTONIO VINICIOS ALVES DA SILVA, CARLOS EDUARDO LIMA MORAIS, HUMBERTO HOLANDA MADEIRA BARROS, KARINE MARTINS TRINDADE, MARCLESSON ALVES, BENEDITO ARRUDA CARNEIRO, ALINE KIMBERLY ALMEIDA RODRIGUES, FABIO TAVORA