By the staff of ASCO Post
Posted: 6/4/2023 10:09:00 AM
The MIRASOL Phase III randomized international clinical trial found that mirvetuximab soravtansine-gynx, an antibody and microtubule inhibitor conjugate, significantly improved progression-free and overall survival for patients with high-grade epithelial ovarian, primary peritoneal, or tube platinum-resistant fallopian tumors with high folate receptor (FR) alpha expression. The research was presented by Kathleen N. Moore, MD, MSat the 2023 ASCO Annual Meeting (Abstract LBA5507).
Kathleen N. Moore, MD, MS
Single-agent chemotherapies have shown limited activity and notable toxicity in patients with platinum-resistant epithelial ovarian cancer. Each subsequent line of therapy is associated with progressively lower response rates, and many patients find it difficult to tolerate further treatments. There have been no new agents specifically indicated for the disease since 2014, when bevacizumab was approved for use with chemotherapy.
The investigational drug used in this study, mirvetuximab soravtansine, demonstrated clinically significant antitumor activity in the single-arm SORAYA study, reported by Matulonis et al in the study Journal of Clinical Oncology in January 2023. The MIRASOL study is a confirmatory Phase III study to test the drug’s efficacy in this setting.
Mirvetuximab soravtansine targets FR, a member of the folate receptor family that is overexpressed on a variety of epithelial-derived cancer cells. When the drug binds to the receptor, it is internalized and leads to cell death.
Patients who received mirvetuximab soravtansine not only lived longer when considering all standard chemotherapy drugs together, but also when compared with each drug alone in this study. Survival outcomes with mirvetuximab soravtansine were also superior to those with physicians’ choice of chemotherapy, whether or not a person received bevacizumab prior to mirvetuximab soravtansine.
With a median follow-up of 13.1 months, in the group of 281 bevacizumab-experienced patients, progression-free survival was 36% better and overall survival was 26% better for those receiving mirvetuximab soravtansine compared to the standard chosen by chemotherapy doctors. In the group of 172 patients who had not received prior bevacizumab, progression-free survival was 34% better and overall survival was 49% better for patients who received mirvetuximab soravtansine compared to physician’s choice of standard chemotherapy .
The adverse event profile of mirvetuximab soravtansine was consistent with previous reports, primarily ocular and low-grade gastrointestinal events. For patients taking mirvetuximab soravtansine, 14% maintained study drug compared with 3% of patients who received standard chemotherapy chosen by the physician.
Mirvetuximab soravtansine has an FDA [U.S. Food and Drug Administration] expedited approval, so hopefully this trial result will lead to quick formal approval. But more importantly, it opens the door globally for the drug to be available outside the United States, where accelerated approval isn’t an option. It’s also worth noting that ongoing studies are evaluating using the drug in the early stages of the disease, said Dr. Moore, associate director of clinical research and co-director of the cancer therapy program at the University of Oklahoma Stephenson Cancer Center.
Mirvetuximab soravtansine has now been shown to be more effective when FR expression is elevated. But the researchers found some efficacy when expression levels were moderate or low, which they hope to examine more definitively in future studies. They also hope to incorporate the drug into earlier lines of therapy, including platinum-sensitive recurrent disease.
Mirvetuximab soravtansine has fewer serious side effects, particularly those that can lead to treatment discontinuation, than standard chemotherapies for patients with platinum-resistant ovarian cancer. This, coupled with the overall survival advantage, demonstrates progress and offers hope for these patients, said the ASCO expert Merry Jennifer Markham, MD, FACP, FASCO.
Disclosure: This research was funded by ImmunoGen, Inc. For complete information on the study authors, visit coi.asco.org.
The content of this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO) and does not necessarily reflect the views and opinions of ASCO.
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