RET inhibitors are targeted therapies that act on tumors with activating alterations in the RET proto-oncogene, such as point mutations or fusions. They fall under the category of the tyrosine kinase inhibitors, which work by inhibiting proteins involved in the abnormal growth of cancer cells. Existing molecules fall in two main categories: the older multikinase inhibitors and the more recent selective inhibitors. Although RET alterations are found at low frequency in a broad range of tumors, the three main indications for RET inhibitors today are non-small cell lung cancer (which harbor RET fusions at a frequency of 1-2%), medullary thyroid cancer (MTC, with activating RET mutations in 25% of cases) and papillary thyroid cancer (PTC, with up to 80% prevalence of fusions depending on the r