PTEN Loss and PD-L1 Expression of Different Histological Patterns of Prostate Cancer

Although several studies have evaluated PTEN loss in Prostatic Adenocarcinoma (PCa), PTEN loss correlation with different histological patterns only has a few studies. Although several studies have evaluated PD-L1 expression in PCa and its correlation with Gleason scores, as far as we know, there are no prior studies that have included a comparison between PD-L1 expression and histological patterns of PCa. This study aims to evaluate PTEN loss and PD-L1 expression by immunohistochemistry in different histological patterns of PCa.

The current study included consecutive 98 radical prostatectomy specimens with 151 foci with different Gleason Grade (GG) patterns.

The highest frequency of PTEN loss was observed in GG4 cribriform and glomeruloid patterns (59.3%, p < 0.001). Combined score (CS) PD-L1 positivity was observed in fourteen patients (14.2%). Tumor cell (TC) and tumor-associated inflammatory cells (IC) PD-L1 positivity was observed in 10 (10.2%) and 7 (7.1%) patients. The highest frequency of PD-L1 expression was observed in the GG5 pattern, and between GG4 patterns, the irregular pattern had the highest PD-L1 positivity.

In conclusion, in our cohort of consecutive unselected cases of prostatic carcinoma, we observed the highest PTEN loss rate in the GG4 cribriform and glomeruloid pattern and the highest PD-L1 expression rate in the GG5 and GG4 irregular patterns. These results may predict molecular differences between different histological patterns in PCa and may be used to inform a treatment decision. Future studies should investigate these differences between histological patterns of PCa to predict response to immunotherapy in larger cohorts.