VENTANA FOLR1 (FOLR1-2.1) RxDx Assay

Predictive IHC assay

VENTANA FOLR1 (FOLR-2.1) RxDx Assay (US FDA Approved)
First IHC companion diagnostic for determining folate receptor alpha (FOLR1) protein expression in EOC patients who may benefit from ELAHERE (mirvetuximab soravtansine)

The VENTANA FOLR1 (FOLR1-2.1) RxDx Assay is the first and only immunohistochemistry (IHC) assay FDA approved to identify epithelial ovarian cancer (EOC) patients eligible for FOLR1-targeted treatment with ELAHERE (mirvetuximab soravtansine).

Ovarian cancer is the fifth overall cause for cancer death in women, representing 5% of all cancer deaths in women.1 It is also the deadliest of gynecological cancers: in 2017, 14,080 women in the US2 and in 2018, 44,576 women in Europe3 died from ovarian cancer. Most women with ovarian cancer present with Stage III or IV disease, contributing to its high mortality rate.4

Folate receptor alpha serves as a predictive biomarker for anti-folate cancer therapy5

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.6  FOLR1 expression is largely restricted to malignant tumors compared to normal tissue, particularly epithelial ovarian cancer (EOC), endometrial cancer, non-small cell lung carcinoma and renal cell cancer. Consequently, FOLR1 is frequently exploited as a target for specific delivery of chemotherapy and immunotherapy agents.7

Intended use

VENTANA FOLR1 (FOLR1-2.1) RxDx Assay is a qualitative immunohistochemical assay using mouse monoclonal anti-FOLR1 clone FOLR1-2.1 intended for use in the assessment of folate receptor alpha (FOLR1) in formalin-fixed, paraffin-embedded epithelial ovarian, fallopian tube, or primary peritoneal cancer tissue specimens by light microscopy. This assay is for use with OptiView DAB IHC Detection Kit for staining on a BenchMark ULTRA instrument.

FOLR1 expression clinical cut-off is ≥ 75% viable tumor cells (TC) with membrane staining at moderate and/or strong intensity levels.

This assay is indicated as an aid in identifying patients with epithelial ovarian, fallopian tube, or primary peritoneal cancer who may be eligible for treatment with ELAHERE (mirvetuximab soravtansine).

Test results of the VENTANA FOLR1 (FOLR1-2.1) RxDx Assay should be interpreted by a qualified pathologist in conjunction with histological examination, relevant clinical information, and proper controls.

This product is intended for in vitro diagnostic (IVD) use.


  1. American Cancer Society. Ovarian Cancer. 2016. < Accessed 16 August 2016>.
  2. National Cancer Institute. Surveillance, Epidemiology and End Results Program. Cancer Stat Facts: Ovarian Cancer. 2016.
  3. WHO. IARC: ovarian cancer estimated incidence, mortality and prevalence. 2018.
  4. Schiffer CA, Anderson KC, Bennett CL, Bernstein S. Elting LS, Goldsmith M, et al. Platelet transfusion for patients with cancer: clinical practice guidelines of the American Society of Clinical Oncology. J Clin Oncol 2001;19(5):1519-38.
  5. Matulonis UA, et al. Abstract LB4. Presented at Society of Gynecologic Oncology 2022 Annual Meeting on Women's Cancer. March 18-21, 2022
  6. Sudimack J, Lee RJ. Targeted drug delivery via the folate receptor. Adv Drug Deliv Rev. 2000, 41:147-62.
  7. Hilgenbrink A., Low P. Folate receptor-mediated drug targeting: From Therapeutics to diagnostics. Journal of Pharmaceutical Sciences. 2005;94(10): 2135-2146.