Selpercatinib is a medication used for the treatment of non-small cell lung cancer, medullary thyroid cancer, and other types of thyroid cancers. The objective of this study is to investigate the efficacy and safety of selective RET-inhibition with selpercatinib in patients with RET-altered thyroid cancers.

 This study included a total of 143 consecutively enrolled patients with RET-mutant medullary thyroid cancer who had or had not previously initiated the treatment with vandetanib, cabozanitib, or both. The patients were assigned to receive selpercatinib. The primary outcome of the study was an objective response (complete or partial), along with the duration of response, safety, and progression-free survival.

Among 55 patients with RET-mutant medullary thyroid cancer who underwent treatment with vandetanib, cabozanitib, or both, 69% experienced a response; the rate of 1-year progression-free survival was 82%. Among 88 patients who had not previously received vandetanib or cabozantinib, the percentage response rate was 73%, and 1-year progression-free survival was 92%. Commonly-occurring adverse events of grade-3 or higher were hypertension (21%), increased alanine aminotransferase level (11%), hyponatremia (8%), and diarrhea (5%).

The research concluded that selpercatinib treatment was associated with positive efficacy and low-grade adverse events in patients with RET-altered thyroid cancers who had or had not previously received vandetanib or cabozantinib.

Ref: https://www.nejm.org/doi/full/10.1056/NEJMoa2005651