The antibody drug conjugate mirvetuximab soravtansine-gynx (Elahere™, ImmunoGen, Inc) received accelerated approval on Nov. 14, 2022, for the treatment of folate receptor-alpha (FR-α) positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer, in patients who have been treated with 1 to 3 prior systemic therapies.¹ Patients should be chosen based on results from a companion diagnostic, the immunohistochemistry test VENTANA FOLR1 (FOLR1-2.1) RxDx Assay.²

Mirvetuximab carries a black box warning for severe ocular toxicities and a recommendation for ophthalmic exams before and during treatment. Prophylactic artificial tears and ophthalmic topical steroids should be prescribed for patients. Some type of ocular adverse reaction occurred in 61% of patients during clinical trials; 9% were grade 3 reactions. The median time to onset was 1.2 months.¹

The recommended dosage is 6 mg/kg adjusted ideal body weight (AIBW) administered once every 3 weeks as an intravenous infusion until disease progression or unacceptable toxicity. The dose calculation formula is provided in the prescribing information, available at https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/761310s000lbl.pdf. Premedication with a corticosteroid, antihistamine, antipyretic, and antiemetic is recommended.¹

Other possible serious adverse reactions include interstitial lung disease (including pneumonitis), peripheral neuropathy, intestinal obstruction, ascites, infection, and pleural effusion. This drug should not be givein during pregnancy or breastfeeding.

The approval was based on results from the SORAYA study (study 0417) of 106 patients who had positive FR-α expression and had received 1 to 3 prior therapies; all patients were required to have had bevacizumab. Treatment with mirvetuximab 6 mg/kg AIBW on day 1 of a 3-week cycle resulted in a 31.7% objective response rate, median duration of response of 6.9 months, and median progression-free survival (PFS) of 4.3 months. The complete response rate was 4.8%.^1,3

References

1. Elahere (mirvetuximab soravtansine-gynx). Prescribing information.  ImmunoGen, Inc; 2022. Accessed January 23, 2023. https://www.elahere.com/pdf/prescribing-information.pdf
2. VENTANA FOLR1 (FOLR1–2.1) RxDx Assay. Roche Diagnostics; 2022. Accessed January 23, 2023. https://diagnostics.roche.com/global/en/products/tests/ventana-folr1-folr-2-1-rxdx-assay-us-fda-approved.html
3. Coleman RL, Matulonis U, Lorusso D, et al. Clinical benefit of mirvetuximab soravtansine in ovarian cancer patients with high folate receptor alpha expression: results from the SORAYA study. Int J Gynecol Cancer. 2022;32(Suppl 3):A18-A18. doi:10.1136/ijgc-2022-igcs.30