Malfeasance of KRAS mutations in carcinogenesis

Activating mutations in the KRAS gene (Kirsten rat sarcoma 2 viral oncogene homolog gene) are commonly seen across the various solid organ and hematolymphoid neoplasms. With the likelihood of the mutation specific KRAS inhibitor entering clinical practice, the present studies profiled the landscape of these mutations in the Indian population to add to databases and posit the clinical utility of its emerging inhibitors. This study included 489 formalin fixed paraffin-embedded (FFPE) tissue samples from consecutive patients during a 5-year period (2015-2019). The clinical records were obtained from the medical record archives of the institution. Library preparation was done using the Oncomine Assay™. Sequencing was performed using the Ion PGM Hi-Q Sequencing Kit on the Ion Torrent Personal Genome Machine (Ion PGM) as well as on Ion Torrent S5 sequencer using the S5 sequencing kit. Ion Torrent Suite™ Browser version 5.10 and Ion Reporter™ version 5.10 were used for data analysis. A total of 50 cases with KRAS mutations were observed occurring most commonly in the codons 12 and 13. The G12D mutation was the most commonly encountered subtype in our cohort (21/50), whereas the G12C mutation was observed in 5 cases, and interestingly, this mutation was only seen in patients with non-small cell lung carcinoma (NSCLC). In the largest cohort from Indian subcontinent reporting spectrum of KRAS mutations in human cancers, an incidence of 11% was observed across all cancer types. Therapies targeting the G12C mutations can benefit up to 20% KRAS-mutated NSCLC. Building databases of spectrum of KRAS mutations in different populations across diverse cancer types is the anticipatory step to this end.