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FDA OKs RET Inhibitor for Lung, Thyroid Cancers

— High response rates with selpercatinib in treated, untreated disease

MedpageToday
selpercatinib(Retevmo) over a computer rendering of the lungs and thyroid gland with cancer cells above FDA APPROVED

WASHINGTON -- The FDA as the first specific treatment for metastatic non-small cell lung cancer (NSCLC) or thyroid cancer with rearranged during transfection (RET) gene fusions.

A selective inhibitor of the RET kinase, selpercatinib received the indication through FDA's accelerated approval process, which requires the sponsor, Eli Lilly, to conduct additional studies to confirm the safety and efficacy of the drug as a condition of final approval.

"Innovations in gene-specific therapies continue to advance the practice of medicine at a rapid pace and offer options to patients who previously had few," Richard Pazdur, MD, of the FDA Office of Oncologic Diseases, said in a statement. "The FDA is committed to reviewing treatments like Retevmo that are targeted to specific subsets of patients with cancer."

Support for the accelerated approval came from the trial. The trial included the three types of patients covered by the accelerated approval: metastatic NSCLC in adults, advanced/metastatic medullary thyroid cancer (MTC) in children and adults, and advanced RET fusion-positive thyroid cancer in children and adults no longer responsive to radioactive iodine (RAI) or not candidates for RAI.

The results showed a 64% response rate in the first 105 patients with NSCLC enrolled in the trial, as reported at the 2019 World Conference on Lung Cancer. Responses persisted for at least 6 months in 81% of cases. In a subgroup of 39 previously untreated patients, selpercatinib led to an overall response rate (ORR) of 84%.

The trial also included 143 patients with previously treated or untreated advanced/metastatic RET-mutant MTC. In the 55 patients with previously treated disease, selpercatinib led to an ORR of 69%, which lasted at least 6 months in 76% of cases. The ORR was 73% in the 88 patients who received selpercatinib as initial therapy, and 61% of responses lasted 6 months or longer.

Among the 19 patients with RET-positive thyroid cancer previously treated with or not candidates for RAI, the ORR was 79%, and 87% of responses lasted at least 6 months. An additional nine patients with previously untreated disease all had objective responses with selpercatinib, and three-fourths of the responses lasted 6 months or longer.

The most common side effects associated with selpercatinib (all grades) in LIBRETTO-001 were increased liver enzymes, hyperglycemia, leukopenia, hypoalbuminemia, hypocalcemia, dry mouth, diarrhea, increased creatinine, hyperphosphatemia, hypertension, fatigue, edema, thrombocytopenia, hypercholesterolemia, rash, constipation, and hyponatremia.

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    Charles Bankhead is senior editor for oncology and also covers urology, dermatology, and ophthalmology. He joined 鶹ý in 2007.