FDA OKs Targeted Therapy Combo for Anaplastic Thyroid Cancer

Nick Mulcahy

May 04, 2018

The US Food and Drug Administration (FDA) today approved dabrafenib (Tafinlar, Novartis) and trametinib (Mekinist, Novartis) as a combination therapy for anaplastic thyroid cancer (ATC) that is BRAF V600E mutation positive and either cannot be surgically excised or is metastatic

"This is the first FDA-approved treatment for patients with this aggressive form of thyroid cancer," said Richard Pazdur, MD, acting director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research.

He also noted that ATC is the third cancer with this specific gene mutation that this drug combination is approved to treat; the combo is also indicated for BRAF-positive metastatic melanoma and non-small cell lung cancer. "This approval demonstrates that targeting the same molecular pathway in diverse diseases is an effective way to expedite the development of treatments that may help more patients," said Pazdur.

ATC is an aggressive, poor-prognosis type of thyroid cancer but is rare, accounting for only 1% to 2% of all thyroid cancers. The National Institutes of Health estimates that there will be 53,990 new cases of thyroid cancer in 2018.

The efficacy of the combination of dabrafenib and trametinib in treating ATC was established in an open-label clinical trial of patients with rare cancers with the BRAF V600E mutation. However, the FDA also explained that data from trials in metastatic melanoma and lung cancer and in other BRAF V600E mutation–positive rare cancers "provided confidence in the results seen in patients with ATC."

In the open-label trial, investigators reported that, of 23 evaluable patients, 57% experienced a partial response and 4% experienced a complete response; in 9 (64%) of the 14 patients with responses, there were no significant tumor growths for 6 months or longer.

The side effects of the combination in patients with ATC are consistent with those seen in previous combined use of the two drugs. Common side effects include pyrexia, rash, chills, headache, arthralgia, cough, fatigue, nausea, vomiting, diarrhea, muscle pain, dry skin, decreased appetite, edema, hemorrhage, hypertension, and dyspnea. 

The FDA also noted that the severe side effects of dabrafenib include new cancers, growth of BRAF wild-type tumors, bleeding, heart problems, eye problems, fever, skin reactions, worsening diabetes, and anemia. 

Severe side effects of trametinib include the development of new cancers, bleeding, inflammation and perforation of the intestines, blood clots, heart problems, eye problems, lung or respiratory problems, fever, skin reactions, and worsening diabetes.

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