Based on efficacy data from clinical trials, two highly selective RET inhibitors selpercatinib and pralsetinib were approved by the FDA in the year 2020 for treating patients with metastatic RET fusion-positive non-small cell lung cancer (NSCLC), advanced or metastatic RET-mutant MTC and advanced or metastatic RET fusion-positive thyroid cancer [16–19]. This evidence concerns the gene RET and medullary thyroid gland carcinoma.