The Food and Drug Administration (FDA) has granted accelerated approval of selpercatinib (Retevmo) to treat adults with metastatic RET fusion-positive non-small cell lung cancer, adults and children 12 years and older with advanced or metastatic RET-mutant medullary thyroid cancer, and adults and children 12 years and older with advanced or metastatic RET fusion-positive thyroid cancer who are radioactive iodine-refractory.

The RET gene provides instructions for cell growth and development. RET mutations can activate RET fusion protein and result in tumor cell proliferation. Selpercatinib is a kinase inhibitor that functions as an antitumor agent in RET proteins that have mutated.

Selpercatinib's efficacy was determined in open-label, multicohort clinical trials of patients whose tumors had RET alterations. For each cancer studied, most patients receiving selpercatinib had a positive tumor response for six months or longer.

Selpercatinib carries several warnings related to potentially serious adverse effects, including hepatotoxicity, hypertension, QT interval prolongation, hemorrhage, hypersensitivity, risk of impaired wound healing, and embryo-fetal toxicity.

The most common adverse effects in the clinical trials of selpercatinib were laboratory abnormalities including increased aspartate aminotransferase, alanine aminotransferase, glucose, creatinine, alkaline phosphatase, and total cholesterol; and decreased leukocytes, albumin, calcium, platelets, and sodium. Other common adverse effects were dry mouth, diarrhea, hypertension, fatigue, edema, rash, and constipation.

Drug interactions can occur with acid-reducing agents, strong or moderate cytochrome P-450 (CYP) 3A inhibitors, strong or moderate CYP3A inducers, and CYP2C8 and CYP3A substrates. Nurses should use a drug database to confirm that any coprescribed therapy is not contraindicated.

For complete prescribing information for selpercatinib, go to http://www.accessdata.fda.gov/drugsatfda_docs/label/2020/213246s000lbl.pdf.