FDA Approves Companion Diagnostic FOLR1-2.1 for Identification of Epithelial Ovarian Cancer Eligible for Mirvetuximab Soravtansine-gynx


The VENTANA FOLR1 RxDx Assay has received approval from the FDA for identifying epithelial ovarian cancer in patients who may be eligible for treatment with mirvetuximab soravtansine-gynx.

The FDA has granted approval to the VENTANA FOLR1 (FOLR1-2.1) RxDx Assay, an immunohistochemistry (IHC)–based companion diagnostic, to identify epithelial ovarian cancer in patients who could be eligible to receive targeted treatment with mirvetuximab soravtansine-gynx (Elahere), according to a press release from Roche.1

The regulatory decision was based on results from the phase 3 SORAYA study (NCT04296890), which indicated that roughly 35% of patients with ovarian cancer expressed high levels of folate receptor α (FRα), defined as 75% or more tumor cells staining with 2+ or 3+ intensity. FRα positivity was determined using the FOLR1-2.1 RxDx Assay. Additionally, approximately 32% of FRα-positive patients had a partial or complete response to mirvetuximab soravtansine treatment.

“This test will enable clinicians to make more informed treatment decisions for patients with ovarian cancer by quickly determining whether they qualify for [mirvetuximab soravtansine] therapy, potentially improving their outcomes,” Jill German, head of Pathology Lab at Roche Diagnostics, said in the press release

The FOLR-2.1 RxDx Assay is a qualitative IHC assay that uses mouse monoclonal anti-folate receptor 1 protein (FOLR1) clone FOLR1-2.1 that detects FRα, which is overexpressed in most ovarian cancers. The assay identifies FRα in formalin-fixed, paraffin-embedded epithelial ovarian cancer, such as primary peritoneal cancer and primary fallopian tube cancer, via light microscopy.

Mirvetuximab soravtansine was previously granted accelerated approval by the FDA for the treatment of FRα-positive platinum-resistant ovarian cancer in November 2022.2 The FDA based its approval on the same results from the SORAYA trial. The phase 3 SORAYA study included a total of 105 efficacy evaluable patients who received single-agent mirvetuximab soravtansine at 6 mg/kg adjusted ideal body weight administered on day 1 of every 3-week cycle.

The primary end point of the SORAYA study was objective response rate up to 2 years. Key secondary end points included duration of response, adverse effect incidence, progression-free survival, overall survival, and CA-125 response.

Patients 18 years and older with a confirmed diagnosis of high-grade serous epithelial ovarian cancer, primary peritoneal cancer, or fallopian tube cancer were eligible to enroll on the study. Additional inclusion criteria included having platinum-resistant disease, progressing radiographically on or after the most recent line of therapy, willingness to provide an archival tumor tissue block or slides, and having a tumor that was positive for FRα expression as identified by the FOLR1-2.1 RxDx Assay.


  1. Roche receives FDA approval for VENTANA FOLR1 (FOLR1-2.1) RxDx Assay as the first IHC-based companion diagnostic to identify ovarian cancer patients eligible for ELAHERE. News release. Roche. November 14, 2022. Accessed November 16, 2022. bit.ly/3AknJ62
  2. ImmunoGen announces FDA accelerated approval of ELAHERE™ (mirvetuximab soravtansine-gynx) for the treatment of platinum-resistant ovarian cancer. News release. ImmunoGen. November 14, 2022. Accessed November 16, 2022. https://bwnews.pr/3AayMyH
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