This assay is intended for the qualitative detection of FOLR-1/ FRα in formalin fixed, paraffin embedded (FFPE) ovarian carcinoma tissue stained with a BenchMark ULTRA instrument. The mouse monoclonal primary antibody in the VENTANA FOLR1 (FOLR1-2.1) RxDx Assay binds to the FOLR1 protein in paraffin-embedded tissue sections. The specific antibody can be visualized using Optiview DAB IHC Detection Kit. Results are interpreted by a pathologist using a light microscope, as an aid in identifying patients with epithelial ovarian cancer, including primary peritoneal cancer and primary fallopian tube cancer eligible for treatment with FOLR1-targeted therapy.
The Folate Receptor 1 protein (FOLR1), also commonly known as Folate Receptor alpha (FRα), is a 38-40 kDA glycosylphosphatidylinositol (GPI)-anchored cell surface protein encoded by the FOLR1 gene, that is largely restricted to malignant tumors compared to normal tissue. The FOLR1 protein mediates the transfer of carbon unit necessary for de novo synthesis of purines and thymidylate, and is required for synthesizing DNA, RNA, and enzymes cofactors. Tumors have increased metabolic demands as a consequence of their enhanced proliferation, and thus, a higher demand for thymidylate and purines compared to normal tissues. Exploiting this biologic necessity for enhanced folate uptake provides an opportunity for anti-folate cancer therapy.
FOLR1 shows limited normal tissue expression and high expression on the surface of solid tumors, particularly epithelial ovarian cancer (EOC), endometrial cancer, nonsmall cell lung carcinoma, and renal cell cancer. FOLR1 levels are positively associated with tumor stage and grade, which suggests that FOLR1 might confer growth advantage of the tumor by modulating folate uptake or by generating regulatory signals. The FOLR1 protein is either absent from normal tissues or localized to the luminal surface of certain epithelial cells, where it is inaccessible to the circulation, whereas in tumors, FOLR1 is fully accessible to the circulation. Therefore, FOLR1 is frequently exploited as a target for receptor specific delivery of chemotherapy and immunotherapy agents.