Assessment of KRAS and NRAS status in metastatic colorectal cancer: Experience of the National Institute of Oncology in Rabat Morocco

Introduction: RAS status is a predictive biomarker for anti-EGFR response in metastatic colorectal cancer (mCRC). The Idylla technology (IT) is a fully automated molecular testing system based on real-time PCR and provides rapid results in a very short preparation time. In this study, we aimed to evaluate the full RAS mutation status in Moroccan patients with mCRC.Methods: formalin-fixed, paraffin-embedded (FFPE) specimens obtained between January 22 and December 15, 2020, were analyzed using the IT. The minimum percentage of tumor cells was 10.0%, after morphological control. One to five-micron sections were collected via a dedicated microtome and inserted directly into the Idylla cartridge.Results: 195 mCRC samples were tested for RAS mutation, 9 (4.6%) could not be treated due to insufficient tumor material. A total of 186 mCRC patients were included in this study, 50.0% were women and 50.0% were men, the mean age was 60.9 years with extremes ranging from 19 to 90 years. The primary site was the most common (83.9%) and the most common histological type was adenocarcinoma (89.8%). 56.5% of tumors were KRAS mutants and the majority of mutations resulted in an amino acid substitution of glycine for aspartic acid. The most frequent mutations were the G>T transversions (41.0%) and the G>A transitions (40.9%). In contrast, NRAS mutations were detected in 8 patients (4.0%). No statistically significant relationship between mCRC patient characteristics and KRAS/NRAS mutations was found.Conclusions: Several studies have shown that the Idylla? KRAS mutation assay can be applied as a routine tool without requiring infrastructure or molecular expertise, to guide the personalized treatment of CRC patients. Our results suggest that KRAS mutations are more common in Moroccan mCRC patients, which is in agreement with previous studies. Further studies with a larger number of mCRC patients are recommended to confirm our results.