This gene encodes the catalytic subunit of DNA polymerase epsilon. The enzyme is involved in DNA repair and chromosomal DNA replication. Mutations in this gene have been associated with colorectal and endometrial cancer. P285R is the most common recurrent mutation of POLE in those types of cancers. Somatic POLE mutation is associated with approximately 3% of sporadic microsatellite-stable (MSS) but hypermutated CRCs.

Vemurafenib Dabrafenib Dabrafenib + Trametinib Vemurafenib + Cobimetinib Vemurafenib + Panitumumab Encorafenib + Binimetinib + Cetuximab Radiation + Trametinib + Fluorouracil

KRAS is a gene that encodes one of the several proteins in the epidermal growth factor receptor (EGFR) signaling pathway that is important in the development and progression of cancer. KRAS can harbor oncogenic mutations that yield a constitutively active protein. Such mutations are found in approximately 30% to 50% of metastatic colorectal tumors and are common in other tumor types. Mutations in the KRAS gene may indicate poor prognosis and poor drug response with therapies targeted to EGFR. The absence of a KRAS mutation predicts a greater likelihood of response to EGFR-targeted therapies and improved survival with such treatment. The relevant KRAS mutation is in one of five codons (12 13, 61, 117 or 146). The presence of KRAS mutations in codon 12, 13 or 61 is associated with a high likelihood of resistance to therapies targeting EGFR. However, preclinical studies have shown that G13D mutant cell lines have intermediate sensitivity to cetuximab and panitumumab. Results should be interpreted in conjunction with other laboratory and clinical findings.

In colorectal cancer, EGFR gene amplification is associated with sensitivity EGFR-targeted therapies, such as Erbitux and Vectibix.

FGFR1 amplification may be associated with sensitivity to the multitargeted tyrosine kinase inhibitor pazopanib in some tumor types.

FGFR1 activating mutations may be associated with response to the multitargeted tyrosine kinase inhibitor pazopanib.

Somatic mutations in PIK3CA have been found in 10-30% of colorectal cancers. KRAS, NRAS, BRAF and PIK3CA and non-functional PTEN predict resistance to anti-EGFR therapies in metastatic colorectal cancer. According to some reports, co-occurrence of both exon 9 and exon 20 PIK3CA mutations, when present, may be associated with a poor prognosis. Recent 'molecular pathological epidemiology' (MPE) research has shown that aspirin use may be associated with better prognosis and clinical outcome in PIK3CA-mutated colorectal carcinoma, suggesting somatic PIK3CA mutation may be a molecular biomarker that predicts response to aspirin therapy. PIK3CA may also be a target of directed therapy in some clinical settings.

NRAS mutations occur in approximately 1--6% of colorectal cancers. Several studies have shown that patients with NRAS-mutated tumors are less likely to respond to cetuximab or panitumumab, but this may not have an effect on PFS or overall survival.

KRAS is a gene that encodes one of the several proteins in the epidermal growth factor receptor (EGFR) signaling pathway that is important in the development and progression of cancer. KRAS can harbor oncogenic mutations that yield a constitutively active protein. Such mutations are found in approximately 30% to 50% of metastatic colorectal tumors and are common in other tumor types. Mutations in the KRAS gene may indicate poor prognosis and poor drug response with therapies targeted to EGFR. The absence of a KRAS mutation predicts a greater likelihood of response to EGFR-targeted therapies and improved survival with such treatment. The relevant KRAS mutation is in one of five codons (12 13, 61, 117 or 146). The presence of KRAS mutations in codon 12, 13 or 61 is associated with a high likelihood of resistance to therapies targeting EGFR. In addition, mutations at codons 117 and 146 may also be associated with reduced response to EGFR-targeted therapies. Results should be interpreted in conjunction with other laboratory and clinical findings. Drug resistance: Panitumumab Cetuximab

Presence of a BRAF c.1799T>A, p.Val600Glu (V600E) mutation in a microsatellite unstable colorectal carcinoma indicates that the tumor is probably sporadic and not associated with Lynch syndrome (HNPCC). However, if a BRAF mutation is not detected, the tumor may either be sporadic or Lynch syndrome associated. Detection of BRAF mutations may also be useful in determining patient eligibility for anti-EGFR treatment. Approximately 8--15% of colorectal cancer (CRC) tumors harbor BRAF mutations. The presence of BRAF mutation is significantly associated with right-sided colon cancers and is associated with decreased overall survival. Some studies have reported that patients with metastatic CRC (mCRC) that harbor BRAF mutations do not respond to anti-EGFR antibody agents cetuximab or panitumumab in the chemotherapy-refractory setting. BRAF V600-mutated CRCs may not be sensitive to V600E targeted TKIs. Drug: Vemurafenib + Panitumumab, Encorafenib + Binimetinib + Cetuximab, Radiation + Trametinib + Fluorouracil