MiR-31-5p: a tiny little messenger that could predict if treatment will benefit colorectal cancer patients

This study evaluated whether specific microRNA expression was predictive of anti-epidermal growth factor receptor (anti-EGFR) treatment success in patients with metastatic colorectal cancer (late stage cancer that has spread to distant sites).

MicroRNA’s are small messengers that help to regulate expression of genes. Recent studies have shown that dysregulation (not working in the way they should) of some microRNAs is associated with the incidence of colorectal cancer. In addition, altered levels of microRNAs may reduce a patients’ sensitivity to certain anti-cancer drugs.

A new group of anti-cancer drugs (including cetuximab [Erbitux] and panitumumab [Vectibix]) bind to the EGFR protein and block its effects. As EGFR is involved in cancer growth these drugs can help slow the cancer. However, anti-EGFR drugs are not effective for all patients and it would be useful to find markers that can predict their success. In this study the authors suspect that the microRNA, miR-31-5p, could be a useful marker of anti-EGFR treatment success.

This study included 102 patients with metastatic colorectal cancer. All patients underwent surgery for colorectal cancer and were treated with anti-EGFR therapy. None of the patients had received chemotherapy before surgery, received radiotherapy or had a mutated KRAS gene (a known predictor of poor outcome following anti-EGFR drugs). The presence of miR-31-5p and other gene mutations associated with colorectal cancer was analyzed in patient samples (KRAS, NRAS and BRAF). Overall survival and progression-free survival (time following treatment before the disease progresses) were also evaluated.

Gene analysis confirmed that KRAS was mutated in 6.9% of patients, NRAS was mutated in 6.9% of patients and BRAF was mutated in 5.9% of patients. Patients with no mutations had better (6.4 months) progression-free survival than patients with at least one mutation (2.1 months). There was no significant difference in survival for patients with or without mutations.

High miR-31-5p levels were found in 11% of patients and was significantly associated with shorter progression free survival (2.8 months compared to 6.1 months for patients with low miR-31-5p). Even in colorectal cancer patients with none of the gene mutations, high miR-31-5p was linked to shorter progression-free survival.

The authors concluded that high miR-31-5p expression was associated with shorter progression-free survival in patients with metastatic colorectal cancer treated with anti-EGFR therapeutics. They also suggest that it may be a useful marker to predict outcomes from anti-EGFR therapy.