Folate receptor alpha (FRA) expression remains unchanged in epithelial ovarian and endometrial cancer after chemotherapy

- Both epithelial ovarian and endometrial cancer demonstrate high expression of FRA compared to normal ovarian and endometrial tissue.
- FRA expression is not altered by chemotherapy exposure at interval debulking surgery or at recurrence.
- Immunohistochemical FRA staining at diagnosis can guide the decision whether to use FRA targeted therapy upon recurrence.

ObjectiveBased on its expression profile, folate receptor alpha (FRA) is an attractive candidate for targeted diagnostics and therapeutics. However, applicability of these agents in residual or recurrent disease could be influenced by chemotherapy. We evaluated whether chemotherapy modified FRA expression in non-mucinous epithelial ovarian (EOC) and endometrial carcinoma (EC).MethodsFRA staining was evaluated by immunohistochemistry, using MAb 26B3, in 81 patients (41 EOCs and 40 ECs) and 17 control tissues (5 benign ovarian cysts, 5 normal ovarian, and 7 normal endometrial tissues). Chemotherapy effect was evaluated in 42 patients (30 paired samples at primary and interval debulking surgery and 12 from primary and recurrent disease). FRA expression was assessed using a semi-quantitative staining algorithm, the M-score (range 0-50).ResultsMedian difference in M-score between tumor and control samples was 27.5 for EOC (95% CI 10.0 to 45.0) and 6.7 for EC (95% CI − 6.7 to 21.7). Paired samples from both primary and interval debulking surgery did not differ in FRA expression in EOC (median difference of M-score between paired samples of 0.0 [95% CI − 2.6 to 2.6]). Recurrent EOC tumors reflected FRA status at diagnosis (median difference of M-score between paired samples of 3.3 [95% CI − 7.0 to 13.6]).ConclusionsThis study shows no significant difference in FRA expression after chemotherapy, strengthening the rationale for FRA targeted diagnostics and therapeutics in FRA expressing tumors, whether newly diagnosed or at recurrence.