The new VENTANA FOLR1 RxDx Assay has been approved by the FDA and will aid in identifying patients with ovarian cancer who are eligible for targeted treatment with mirvetuximab soravtansine.
The FDA has granted approval to the VENTANA FOLR1 (FOLR1-2.1) RxDx Assay, the first immunohistochemistry (IHC) companion diagnostic test to aid in identifying patients with epithelial ovarian cancer (EOC) who are eligible for targeted treatment with mirvetuximab soravtansine-gynx (Elahere), according to Roche.1
Approval of the assay is based on the results of the SORAYA clinical study (NCT04296890) which evaluated the safety and efficacy of mirvetuximab soravtansine in patients with platinum-resistant high-grade serous EOC, primary peritoneal, or fallopian tube cancer, whose tumors express a high-level of folate receptor alpha (FRα).
Findings from the study showed that the primary end point of achieving meaningful anti-tumor activity with consistent safety and favorable tolerability was met with approximately 35% of patients with ovarian cancer expressed high levels of FRα and were considered FRα-positive by the VENTANA FOLR1 RxDx Assay. Among the patients who were FRα-positive, about 32% elicited a partial or complete response to treatment with mirvetuximab soravtansine.
"We're proud to expand our women's health and oncology portfolios through the addition of the first companion diagnostic IHC test for ovarian cancer," said Jill German, head of pathology lab at Roche Diagnostics, in the press release. "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."
The folate receptor 1 protein (FOLR1), also known as FRɑ, is expressed in approximately 90% of patients with ovarian carcinomas. This protein acts as a predictive biomarker for FOLR1-targeted therapy for patients with EOC.
With this new VENTANA FOLR1 RxDx Assay, clinicians are provided with a new tool to help assess the likelihood of the potential benefit from FOLR1 therapy for patients who are eligible for mirvetuximab soravtansine.
Additionally, mirvetuximab soravtansine, a first-in-class antibody-drug conjugate therapy, was granted an accelerated approval by the FDA for the treatment of patients with FRɑ-positive platinum-resistant ovarian cancer as a result of data from the SORAYA trial.
In the open-label, single arm study, 106 patients were enrolled and treated with mirvetuximab soravtansine monotherapy at a dose of 6 mg/kg adjusted by ideal body weight which was given on day 1 of every 3-week cycle. Patients had a median of 3 prior lines of therapy with 51% of patients having received 3 prior lines of therapy and 48% with 1-2 prior lines of therapy.2
Female patients who were 18 years of age and older with a confirmed diagnosis of high-grade serous EOC, primary peritoneal cancer, or fallopian tube cancer were included in the study. Patients must have progressed radiographically on or after their most recent line of anticancer therapy, have an ECOG performance status of 0-1, at least 1 lesion that meets the definition of measurable disease by RECIST v1.1, and adequate hematologic, liver and kidney function. Further, all enrolled patients had received prior bevacizumab (Avastin), and 48% of patients received a prior PARP inhibitor.
On November 16, 2021, the data cutoff date, patients in the overall efficacy patient population (n = 105) who were treated with mirvetuximab soravtansine elicited an ORR of 31.7% (95% CI, 22.9%-41.6%). Per investigator assessment, the median DOR was 6.9 months (95% CI: 5.6, 9.7).
Regarding safety, treatment-related adverse events (TRAEs) led to dose reductions in 19% of patients, dose delays in 32%, and discontinuations in 7%.2 The most common adverse events (AEs) reported were seen in 20% of patients or greater and included laboratory abnormalities, vision impairment, fatigue, increased aspartate aminotransferase, nausea, increased alanine aminotransferase, keratopathy, abdominal pain, decreased lymphocytes, peripheral neuropathy, diarrhea, decreased albumin, constipation, increased alkaline phosphatase, dry eye, decreased magnesium, decreased leukocytes, decreased neutrophils, and decreased hemoglobin.