Selpercatinib is currently recommended over multikinase inhibitors, such as vandetanib, for RET-altered MTC, based on improved outcomes in both randomized and non-randomized clinical trials, along with a lower incidence of treatment-related adverse events [1]. ACTH production was managed with metyrapone, which was successfully terminated promptly due to the favorable response to selpercatinib. The gene discussed is RET; the disease is medullary thyroid gland carcinoma.