Efficacy of encorafenib and cetuximab therapy in a young patient with a rare concomitant KRAS and BRAF mutation in primary rectal cancer and wild-type KRAS status in metastases: A case report and literature review

The presence of activating somatic mutations in the KRAS and NRAS oncogenes is a negative predictor of treatment with the anti-epidermal growth factor receptor (EGFR) monoclonal antibody in colorectal cancer. The BRAF oncogene also plays an important role in carcinogenesis, and, in colorectal cancer, is associated with an unfavorable prognosis. Mutations in RAS and BRAF are usually considered mutually exclusive. Concomitant mutations present in these oncogenes are rare. However, according to recent analyzes, the incidence of concomitant RAS and BRAF mutations in colorectal cancer may be higher than it is currently expected. In the presented case report of a 44-year-old woman treated for metastatic rectal cancer with concomitant KRAS and BRAF mutations in primary tumor and wild-type KRAS status in metastases, we demonstrated improved survival outcome and quality of life after treatment with BRAF inhibitor encorafenib and the anti-EGFR monoclonal antibody cetuximab.Patient Consent Statement: Written informed consent was obtained from the patient's family for the publication of this report.