Avutometinib-Defactinib Combination Shows 45% Response Rate in Low-Grade Serous Ovarian Cancer
Key Insights
A phase II trial of avutometinib combined with defactinib demonstrated a 45% response rate in patients with advanced low-grade serous ovarian cancer, nearly twice as effective as current best treatments.
Patients with KRAS (search) mutations showed particularly strong responses at 60%, while those without mutations still achieved a 29% response rate, both significantly higher than standard therapy response rates of 0-14%.
The dual RAF (search)/MEK (search) inhibitor combination proved over four times more effective than avutometinib alone, with previous phase I data showing an average progression-free survival of 23 months.
A targeted drug combination for patients with low-grade serous ovarian cancer demonstrated nearly twice the effectiveness of current best treatments in interim results from the international RAMP-201 phase II study presented at the 2023 American Society of Clinical Oncology Annual Meeting. The combination of avutometinib and defactinib achieved a 45% response rate in 29 patients with advanced low-grade serous ovarian cancer (LGSOC), a rare form of the disease with historically poor treatment outcomes.
Superior Efficacy Across Patient Subgroups
The drug combination showed particularly promising results in patients with KRAS (search) mutations, with 60% experiencing significant tumor shrinkage. Notably, even patients without KRAS mutations demonstrated encouraging responses, with 29% achieving significant tumor reduction. These response rates represent substantial improvements over current approved treatments, which typically show response rates ranging from 0-14% for chemotherapy and hormone therapy, and 26% for trametinib accessed through the Cancer Drugs Fund in England.
Patients previously treated with other targeted therapies, including MEK (search) inhibitors, also experienced tumor shrinkage following treatment with the avutometinib-defactinib combination, suggesting potential utility in treatment-resistant cases.
Mechanism and Rationale for Combination Therapy
Avutometinib functions as a dual RAF (search) and MEK (search) inhibitor, blocking specific proteins that control cancer growth and survival. However, studies have demonstrated that avutometinib can lose effectiveness over time as tumors develop resistance. The addition of defactinib, designed to combat proteins that encourage drug resistance, appears to enhance avutometinib's efficacy significantly. The combination proved over four times more effective than avutometinib monotherapy in the current study.
Clinical Context and Unmet Need
Low-grade serous ovarian cancer accounts for approximately one in 10 ovarian cancer cases, affecting around 700 women annually in the UK and 80,000 worldwide. The disease tends to affect younger women compared to other ovarian cancer subtypes and demonstrates notably poor response rates to currently approved treatments.
The RAMP-201 study, led by researchers from The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London, and sponsored by Verastem Oncology, builds upon the earlier phase I FRAME trial. While survival data from RAMP-201 remains pending, results from the FRAME trial indicated that patients treated with this drug combination lived an average of 23 months before cancer progression.
Clinical Perspective and Future Implications
Dr. Susana Banerjee, global lead investigator and Consultant Medical Oncologist at The Royal Marsden NHS Foundation Trust, emphasized the potential significance of these findings: "These initial results could be fantastic news for women with low grade serous ovarian cancer, indicating a far more effective option than current treatments may be on the horizon. Low grade serous ovarian cancer does not respond well to currently approved treatments, so these results could represent a significant breakthrough in treating the disease."
The research team expressed hope that this drug combination will eventually become a standard of care for women with low-grade serous ovarian cancer, pending further clinical development and regulatory review.
Patient Experience
The clinical impact of this treatment approach is illustrated by patient Christine Cull, who joined the FRAME trial in August 2020 after exhausting conventional treatment options. Following treatment with the drug combination, her latest scans showed no evidence of disease. "I have scans every three months and each time we've seen the cancer getting smaller and smaller," Cull reported, noting minimal side effects from the treatment regimen.