To assess whether the insensitivity of resistant cells to RET inhibitors resulted from newly acquired mutations in RET oncogene or in other known oncogenic drivers in NSCLC (such as MET or KRAS, already known as mechanisms of resistance to RETi [21]), we conducted a mutational screening for 409 cancer-related gene abnormalities. The gene discussed is KRAS; the disease is non-small cell lung carcinoma.