Patients with metastatic colorectal cancer (mCRC) harboring BRAF V600E mutations benefitted from first-line treatment with the targeted therapies encorafenib and cetuximab plus a mFOLFOX6 chemotherapy regimen, according to results from the Phase III BREAKWATER trial led by researchers at The University of Texas MD Anderson Cancer Center.
The findings, presented today at the American Society of Clinical Oncology Gastrointestinal Cancers (ASCO GI) Annual Symposium and published in Nature Medicine, demonstrated a 60.9% overall response rate (ORR) with the three-drug combination compared to 40% with the standard-of-care (SOC) treatment - chemotherapy with or without bevacizumab. In the experimental arm, 68.7% of patients had a duration of response of at least six months, compared to 34.1% of patients in the SOC arm.
Data from this multi-institutional collaboration across 28 countries supported the accelerated approval of this combination by the Food and Drug Administration (FDA) in Dec. 2024, providing an effective new first-line treatment option for patients with BRAF V600E-mutant mCRC.
"Chemotherapy has had limited efficacy as a first-line treatment in controlling the aggressive tumor growth we see in patients with this mutation," said co-principal investigator Scott Kopetz, M.D., Ph.D., professor of Gastrointestinal Medical Oncology and associate vice president of Translational Integration at MD Anderson. "This new regimen highlights the importance of combining dual-targeted therapy with chemotherapy to improve patient outcomes in the first-line setting, and the durable responses are a significant development as we work to improve quality of life for these patients."
More than 150,000 people are diagnosed with colorectal cancer each year, making it the fourth most common cancer in the U.S., according to the National Cancer Institute. BRAF mutations occur in approximately 8-12% of cases and are associated with aggressive tumor growth, low efficacy from SOC treatments and a poor prognosis, with a median overall survival less than 12 months. Previously, there were no first-line targeted therapies approved for patients with BRAF V600E-mutant mCRC.
The BREAKWATER trial was one of the first studies to utilize the FDA's Project FrontRunner, an initiative to encourage the evaluation of therapies in earlier clinical settings for advanced cancers rather than after patients received numerous previous treatments.
The trial enrolled patients who were at least 16 years of age with previously untreated BRAF V600E-mutant mCRC. Patients were randomized equally to one of three treatment arms: SOC chemotherapy with or without bevacizumab; a dual combination of encorafenib plus cetuximab; or a triple combination of encorafenib, cetuximab and mFOLFOX6.
When researchers analyzed patient subgroups on the trial, the triple combination showed benefits across important groups, including patients with cancer spread to three or more organs and those with liver metastases.
"These results support this combination as a new first-line standard of care for patients with BRAF V600E-mutant metastatic colorectal cancer," Kopetz said. "It also highlights the importance of swiftly identifying molecular subtypes of colorectal cancer at diagnosis to optimize treatment strategies for our patients."
The safety profile of this combination was consistent with the known safety profile of each respective drug. No new safety signals were identified. The most common adverse reactions included nausea, rash, fatigue, vomiting, abdominal pain, diarrhea and decreased appetite, all of which were reported in at least 25% of patients and were similar between arms.
Final calculations of progression-free survival and overall survival will be formally assessed in the next phase of the trial. Future analyses of this trial may shed light on predictive biomarkers for this combination therapy.
The study was sponsored by Pfizer Inc., and Kopetz disclosed consulting for Pfizer and receiving research funding from the company. A full list of collaborating authors and their disclosures can be found in the full paper here.
