|The following article features coverage from the SGO 2022 Annual Meeting on Women’s Cancer. Click here to read more of Cancer Therapy Advisor’s conference coverage.|
Mirvetuximab soravtansine produced “rapid and durable responses” in patients with platinum-resistant, high-grade serous epithelial ovarian, fallopian tube, or primary peritoneal cancers with high folate receptor alpha (FRα) expression, according to a presentation at the SGO 2022 Annual Meeting on Women’s Cancer.
“These results position mirvetuximab to become a practice-changing, biomarker-driven standard of care treatment option for patient with FRα-positive, platinum-resistant ovarian cancer,” said Ursula A. Matulonis, MD, of the Dana-Farber Cancer Institute in Boston, when presenting the results at the meeting.
Dr Matulonis explained that mirvetuximab soravtansine is an antibody-drug conjugate that consists of an FRα-binding antibody, cleavable linker, and maytansinoid DM4, which is a potent tubulin-targeting agent.
Researchers tested mirvetuximab soravtansine in the single-arm, phase 3 SORAYA trial (ClinicalTrials.gov Identifier: NCT04296890). The trial included 106 patients with platinum-resistant, high-grade serous epithelial ovarian, fallopian tube, or primary peritoneal cancers with high FRα expression. High FRα expression was defined as at least 75% of cells staining positive with a 2 or higher staining intensity by immunohistochemistry.
At baseline, the median age was 62 (range, 35-85) years, 80% of patients had epithelial ovarian cancer, 59% had stage III disease, and 38% had stage IV. Twenty percent of patients had a known BRCA mutation, 48% had received a PARP inhibitor, and all patients had previously received bevacizumab.
Patients received mirvetuximab soravtansine at 6 mg/kg once every 3 weeks. The primary endpoint was objective response rate (ORR), and a key secondary endpoint was duration of response (DOR).
The investigator-assessed ORR was 32.4%, with 5 complete responses and 29 partial responses. The ORR was similar regardless of the number of prior lines of therapy or prior PARP inhibitor exposure.
“The response rate is nearly triple the benchmark set in prior studies of less heavily pretreated platinum-resistant ovarian cancer populations. These responses are rapid and durable,” Dr Matulonis said.
Two-thirds of responses occurred at the time of the second cycle, and the median DOR was 6.9 months. The median DOR was similar regardless of the number of prior therapies or exposure to PARP inhibitors. The median progression-free survival was 4.3 months.
The most common treatment-related adverse events (TRAEs) were low-grade, reversible ocular and gastrointestinal events, Dr Matulonis said.
The most common grade 3 TRAEs were blurred vision (6%) and keratopathy (8%). One patient had grade 4 keratopathy. The median time to onset of ocular events was cycle 2. Most ocular events were manageable with dose modifications. The patient with grade 4 keratopathy discontinued treatment, and the keratopathy resolved in 15 days.
Serious grade 3 or higher TRAEs occurred in 8% of patients. A dose delay was required in 32% of patients, a dose reduction was required in 19%, and 7% discontinued treatment due to TRAEs.
There was 1 death due to respiratory failure considered possibly related to mirvetuximab soravtansine. However, an autopsy showed that the patient had lung metastasis, and there was no evidence of a drug reaction.
Dr Matulonis concluded that mirvetuximab soravtansine demonstrated “clinically meaningful antitumor activity in patients with FRα-high, platinum-resistant ovarian cancer.”
Disclosures: This trial is sponsored by ImmunoGen, Inc., in collaboration with IQVIA Biotech. Dr Matulonis disclosed relationships with Novartis, AstraZeneca, Merck, GSK, Trillium, Blueprint Medicines, Agenus, ImmunoGen, NextCure, Ovarian Cancer Research Alliance, Rivkin Foundation, Clearity, Symphogen, Alkermes, and Advaxis.
Read more of Cancer Therapy Advisor’s coverage of SGO 2022 by visiting the conference page.
Matulonis UA, Lorusso D, Oaknin A, et al. Efficacy and safety of mirvetuximab soravtansine in patients with platinum-resistant ovarian cancer with high folate receptor alpha expression: Results from the SORAYA study. Presented at SGO 2022; March 18-21, 2022. Abstract LBA 4.