Phase 1 Trial of Ovarian Cancer Therapy Mirvetuximab Supports Phase 3 Study

Phase 1 Trial of Ovarian Cancer Therapy Mirvetuximab Supports Phase 3 Study

Results from a Phase 1 clinical trial of mirvetuximab soravtansine (IMGN853) as a treatment for  chemotherapy-resistant ovarian cancer and other malignancies have propelled the therapy into a Phase 3 trial.

Researchers used the Phase 1 findings to determine a suitable dose for further trials, according to the treatment’s developer, ImmunoGen.

The study, “Phase 1 Dose-Escalation Study of Mirvetuximab Soravtansine (IMGN853), a Folate Receptor α-Targeting Antibody-Drug Conjugate, in Patients With Solid Tumors,” appeared in the journal Cancer.

“These Phase 1 results have played an important role in determining the appropriate dose for mirvetuximab soravtansine in the recently initiated Phase 3 FORWARD I trial of patients with platinum-resistant ovarian cancer,” said Dr. Kathleen Moore, an associate professor at the Stephenson Cancer Center at the University of Oklahoma, who led the study.

The trial (NCT01609556) tested increasing doses of the treatment in 44 patients with recurrent ovarian, endometrial, kidney, and lung cancer. Ovarian cancer patients made up 52 percent of the group. Participants received the treatment — given intravenously — on day 1 of a 21-day cycle.

Patients were assigned to doses of either 0.15, 0.5, 1.0, 2.0, 3.3, 5.0, or 7.0 mg/kg of mirvetuximab until toxic side effects were noted or the patient’s disease progressed. The testing allowed researchers to set an optimal dose for future trials of 6.0 mg of mirvetuximab per kilogram.

Most adverse events during the trial were mild. The reactions that showed up the most were fatigue, blurred vision and diarrhea.

Although the study was designed to assess the safety and dosing of the treatment, researchers also kept an eye on the treatment’s anti-cancer potential. Two ovarian cancer patients had a partial response to the therapy, the team said.

The results helped researchers design the Phase 3 trial (NCT02631876) for patients with platinum chemotherapy-resistant ovarian cancer.

Meanwhile, researchers published results from a Phase 1b expansion trial (NCT02606305) of the treatment in the Journal of Clinical Oncology. It was titled Safety and Activity of Mirvetuximab Soravtansine (IMGN853), a Folate Receptor Alpha–Targeting Antibody–Drug Conjugate, in Platinum-Resistant Ovarian, Fallopian Tube, or Primary Peritoneal Cancer: A Phase I Expansion Study.”

Twenty-six percent of the 46 patients in the trial responded to the therapy, with one patient having a complete response and 11 partial responses. The median duration of response was 19.1 weeks.

Patients’ median disease-progression-free survival was 4.8 months. Those with fewer rounds of previous treatments had longer progression-free survival times, researchers said.

“The combination of these data and the recent data published in the Journal of Clinical Oncology further support the dose that has been chosen and patients who have been selected for FORWARD I,” said Moore, the lead author of both studies.

Mirvetuximab soravtansine is an antibody-drug conjugate, often referred to as an ADC. The treatment targets the folate receptor alpha, a molecule found on the surface of cancer cells. Once the antibody lands on the tumor surface, the drug part of the treatment kills the cancer cells.

The treatment is intended as a stand-alone treatment for women with ovarian cancer that is resistant to chemotherapy. ImmunoGen is also examining the drug in combination with other treatments.

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