KIF5B and medullary thyroid gland carcinoma: While various RET fusion partners have been identified in multiple cancer types, the KIF5B-RET fusion and the CCDC6-RET fusion are detected most frequently in NSCLC and PTC, respectively.2 Oncogenic RET mutations are found primarily in medullary thyroid cancer (MTC).2 In 2020, the US Food and Drug Administration (FDA) approved the RET protein tyrosine kinase inhibitors (TKIs) selpercatinib (LOXO292) and pralsetinib (BLU667) for advanced and metastatic RET-altered NSCLC and thyroid cancers.