Targeting RET in medullary thyroid cancer.

Medullary thyroid cancer (MTC) is a rare cancer, accounting for 2-3% of all thyroid cancers. Point mutations in the RET proto-oncogene can be detected in 25-65% of MTC. These mutations commonly occur in the cysteine-rich or tyrosine kinase domains, leading to constitutively active tyrosine kinase activity in RET. In the last decade, significant advancements have been made in treating MTC with the advent of tyrosine kinase inhibitors, especially in RET-mutated MTC. Multikinase inhibitors such as vandetanib and cabozantinib were the first few effective inhibitors, which have been shown to slow disease progression in the treatment of advanced MTC. In more recent years, these have been followed by highly selective RET inhibitors selpercatinib and pralsetinib, which have made their way into the clinic, demonstrating high efficacy and a more favourable side-effect profile due to their reduction in off-target effects. In spite of these successes, there remains a continued need to develop strategies to overcome treatment resistance.