A novel combination therapy incorporating immunotherapy has shown promising results in patients with microsatellite stable (MSS) BRAF V600E-mutated colorectal cancer, a rare and difficult-to-treat subtype. The findings, stemming from a clinical trial led by Dr. Van Morris at MD Anderson Cancer Center, suggest a potential new treatment avenue for this aggressive cancer.
The initial standard of care for MSS BRAF V600E colorectal cancer, established in 2015, involved a combination of encorafenib and cetuximab. While this regimen improved patient outcomes, the median survival remained limited to approximately four months. Driven by the observation of a high immune system response in these tumors, Dr. Morris investigated the addition of anti-PD1 immunotherapy to the existing regimen.
Anti-PD1 Therapy Boosts Survival
The clinical trial results revealed a significant improvement in median survival, extending to almost 7.5 months with the addition of anti-PD1 therapy. Notably, two patients exhibited exceptional responses, remaining on the treatment for two years. These findings prompted further investigation into the factors driving these exceptional responses.
"These were amazing results we were not used to seeing in enough of our patients with BRAF-mutated colorectal cancer," said Dr. Morris.
Unlocking Biomarkers of Response
In collaboration with Dr. Anirban Maitra, researchers conducted liquid biopsies to analyze RNA signatures in blood samples from trial participants. The analysis revealed distinct RNA profiles in exceptional responders compared to other patients, suggesting potential biomarkers for predicting treatment success. This research aims to refine patient selection for this therapeutic approach.
Phase II Trial Underway
Building on these promising results, Dr. Morris is now leading a nationwide Phase II clinical trial to further evaluate the combination of encorafenib, cetuximab, and anti-PD1 therapy in MSS BRAF V600E-mutated colorectal cancer. This randomized trial will assess the efficacy of the treatment combination across multiple sites in the United States and incorporate liquid biopsy analysis to identify predictive biomarkers.
The trial is actively enrolling patients and represents a significant step forward in addressing the unmet medical need for effective therapies in this rare and aggressive form of colorectal cancer. The study underscores the importance of personalized medicine approaches and the potential of immunotherapy to improve outcomes in genomically defined cancer subtypes.
