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Título

PD-L1 EXPRESSION IS RARE IN PROSTATE CANCER AND DOES NOT CORRELATE WITH PTEN LOSS

Resumo

BACKGROUD
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.
AIM
We aimed to investigate PD-L1 expression in radical prostatectomy specimens and its correlation with PTEN loss by immunohistochemistry (IHC).
METHODS
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.
RESULTS
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.
CONCLUSION
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.

Palavras Chave ( separado por ; )

PD-L1, PTEN, Prostate cancer, Biomarkers