FDA Approves First IHC Companion Diagnostic for Mirvetuximab Soravtansine in Ovarian Cancer

The FDA has approved the VENTANA FOLR1 (FOLR1-2.1) RxDx assay, the first immunohistochemistry (IHC) companion diagnostic test to help identify patients with epithelial ovarian cancer who are eligible for treatment with mirvetuximab soravtansine-gynx (Elahere).¹

On November 14, 2022, the FDA granted accelerated approval to mirvetuximab soravtansine for the treatment of adult patients with folate receptor α (Frα)–positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer, who have received 1 to 3 prior systemic treatment regimens.

“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,” Jill German, head of the pathology lab at Roche Diagnostics, said in a 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 Elahere therapy, potentially improving their outcomes.”

The approval is based on findings from the phase 3 SORAYA trial (NCT04296890), which enrolled 106 patients with platinum-resistant ovarian cancer whose tumors expressed high levels of FRα. Patients were allowed to have received up to 3 prior lines of systemic treatment, and all were required to have received bevacizumab (Avastin).

In the trial, patients received intravenous mirvetuximab soravtansine at 6 mg/kg once every 3 weeks until progressive disease or unacceptable toxicity. Tumor response assessments were performed every 6 weeks for the first 36 weeks, and every 12 weeks thereafter.

Confirmed investigator-assessed objective response rate (ORR) served as the primary end point, and the key secondary end point was duration of response (DOR) by RECIST v1.1 criteria.

In the study, approximately 35% of patients with ovarian cancer expressed high levels of FRα (defined as ≥ 75% tumor cells staining with 2+/3+ intensity) and were considered FRα-positive by the VENTANA FOLR1 (FOLR1-2.1) RxDx assay. Among the FRα-positive patients, the confirmed investigator-assessed ORR was 31.7% (95% CI, 22.9%-41.6%); this included a complete response rate of 4.8% and a partial response rate of 26.9%.

Moreover, the median DOR was 6.9 months (95% CI, 5.6-9.7) per investigator assessment.

Regarding safety, any-grade adverse effects (AEs) included vision impairment (50%), fatigue (49%), increased aspartate aminotransferase (50%), nausea (40%), increased alanine aminotransferase (39%), keratopathy (37%), abdominal pain (36%), decreased lymphocytes (35%), peripheral neuropathy (33%), diarrhea (31%), decreased albumin (31%), constipation (30%), increased alkaline phosphatase (30%), dry eye (27%), decreased magnesium (27%), decreased leukocytes (26%), decreased neutrophils (26%), and decreased hemoglobin (25%).³

Moreover, 31% of patients experienced serious AEs with the agent, including intestinal obstruction (8%), ascites (4%), infection (3%), and pleural effusion (3%). Fatal toxicities occurred in 2% of patients, and these included small intestinal obstruction (1%) and pneumonitis (1%).

References

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 15, 2022. https://prn.to/3E9kn78
2. ImmunoGen announces FDA accelerated approval of Elahere (mirvetuximab soravtansine-gynx) for the treatment of platinum-resistant ovarian cancer. News release. ImmunoGen Inc. November 14, 2022. Accessed November 15, 2022. http://bit.ly/3GgrCwL
3. Elahere (mirvetuximab soravtansine-gynx). Prescribing information; ImmunoGen Inc; 2022. Accessed November 15, 2022. https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/761310s000lbl.pdf