Increased expression of folate receptor-α (FRA) in triple-negative breast cancer: A potential therapeutic target.

1037 Background: Folate receptor alpha (FRA the product of the FOLR1 gene) has been identified as a potential prognostic and therapeutic target in a number of cancers. A correlation has been shown between intense expression of FRA in breast tumors and poor prognosis, yet little is known about FOLR1/FRA expression across clinically relevant breast cancer subtypes. Methods: 131 breast cancer tumors including 4 benign, 33 ER+, 26 HER2+, and 68 triple negative (TN) were constructed into tissue microarrays (TMAs). FRA expression was analyzed by immunohistochemistry (IHC) using a high affinity FRA antibody. Tumor membrane staining intensity was scored by a pathologist as negative (0), weak (1+), moderate (2+) and strong (3+). The percent of cells within each tissue core stained at each intensity was recorded to calculate an H-score. The H-score is a weighted score that captured both the proportion of positive staining and intensity for each tumor. H-score values can range from zero (no membrane staining) to a m...