In this episode, Dr. Brooke Howitt from Stanford University discusses her team’s recent study on PTEN expression in tubo-ovarian high-grade serous carcinoma (HGSCs). PTEN deficiency (complete or sub-clonal loss) as detected by immunohistochemistry was identified in 13 of the 62 HGSCs (21%) and was significantly correlated with reduced expression of estrogen receptor and worse first progression-free survival (P < .05) but not with PD-L1 expression, or overall survival. Additionally, tumor progression within 1 year of PARP inhibitor therapy was found more frequently in PTEN-deficient cases than in PTEN-intact cases (100% vs 52%).

These findings indicate that PTEN deficiency defines a distinct clinically significant subgroup of HGSCs with a tendency for estrogen receptor negativity, inferior clinical outcomes, and potential drug resistance. These tumors may benefit from PI3K pathway inhibitors in combination with other ovarian cancer regimens.