Not All BRAF-Mutant Metastatic Colorectal Cancers Are Identical: Distinct Clinical Consequences of non-V600 BRAF Mutations

BRAF-mutated colorectal adenocarcinomas: pathological heterogeneity and clinical implications

Advances in molecular biology have markedly increased our understanding of the heterogeneous molecular landscape of colorectal cancer (CRC). Up to 15% of CRCs harbor the BRAF p.V600E somatic mutation (BRAFmt), a well-established negative prognostic marker in patients with metastatic CRC (mCRC). The BEACON CRC trial set a new standard of care in patients with progressive BRAFmt cancers, consisting of the combination of encorafenib and cetuximab. On these bases, BRAF mutational testing is now recommended in patients with mCRC. However, efforts are needed to further stratify patients carrying this mutation. Here, we discuss the heterogeneous pathologic and molecular landscape of BRAFmt CRCs, focusing on the promises and pitfalls of molecular diagnostics, on novel biomarkers to improve patients' stratification and on the current diagnostic scenario for CRC. We believe that a better stratification based on histopathological features and novel molecular biomarkers should be performed to optimize patient management and therapeutic decision-making.

BRAF-Mutated Colorectal Cancer: Clinical and Molecular Insights

Colorectal cancer (CRC) is one of the leading causes of mortality and morbidity in the world. It is a heterogeneous disease, which can be classified into different subtypes, characterized by specific molecular and morphological alterations. In this context, BRAF mutations are found in about 10% of CRC patients and define a particular subtype, characterized by a dismal prognosis, with a median survival of less than 12 months. Chemotherapy plus bevacizumab is the current standard therapy in first-line treatment of BRAF-mutated metastatic CRC (mCRC), with triplet (FOLFOXIRI) plus bevacizumab as a valid option in patients with a good performance status. BRAF inhibitors are not so effective as compared to melanoma, because of various resistance mechanisms. However, the recently published results of the BEACON trial will establish a new standard of care in this setting. This review provides insights into the molecular underpinnings underlying the resistance to standard treatment of BRAF-mutated CRCs, with a focus on their molecular heterogeneity and on the research perspectives both from a translational and a clinical point of view.

The Winding Roadmap of Biomarkers toward Clinic: Lessons from Predictors of Resistance to Anti-EGFRs in Metastatic Colorectal Cancer

In the evolving molecular landscape of metastatic colorectal cancer, optimizing available tools to select patients to receive anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibodies is a modern challenge of colorectal oncologists. Several molecular biomarkers have been investigated in recent years as potential predictors of resistance to anti-EGFR agents in preclinical and clinical retrospective series. Nevertheless, none of them have been implemented in clinical practice due to the lack of a formal prospective demonstration. Here, we propose a literature review of molecular alterations associated with resistance to anti-EGFRs, underlining the reasons why their roadmap from laboratories to clinics was prematurely halted.