FDA Approves Combination for Rare Thyroid Cancer Type

The Food and Drug Administration (FDA) approved the two-drug combination Tafinlar (dabrafenib) and Mekinist (trametinib) to treat patients with metastatic or unresectable anaplastic thyroid cancer (ATC), whose tumors harbor the BRAF V600E mutation.

ATC is a rare and aggressive type of thyroid cancer, making up about 1 to 2 percent of all thyroid cancer diagnoses.

The approval was based on an open-label clinical trial of patients with BRAF V600E-postive rare cancers. Fifty-seven percent of the 23 patients on the trial experienced a partial response, and 4 percent had a complete response on the combination. Of all the patients who had a response, 64 percent of them did not have significant tumor growth for at least six months.

“This is the first FDA-approved treatment for patients with this aggressive form of thyroid cancer, and the third cancer with this specific gene mutation that this drug combination has been approved to treat,” Richard Pazdur, M.D., director of the FDA’s Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, said in an FDA-issued statement.

“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,” he added.

As of earlier this week, the two drugs were also approved — either aloneor as a combination – to be used for patients with melanoma, as well as those with non-small cell lung cancer (NSCLC).

Side effects for patients with ATC were similar to those seen with the drug duo in melanoma. Common side effects included fever, rash, chills, headache, joint pain, cough, fatigue, nausea, vomiting, diarrhea, muscle pain, dry skin, decreased appetite, edema, hemorrhage, high blood pressure and difficulty breathing.

Severe side effects of the combination included development of new cancers, serious bleeding problems, inflammation of intestines and perforation of the intestines, blood clots in the arms, legs or lungs, heart problems, severe eye problems, lung or breathing problems, severe fever, serious skin reactions, high blood sugar or worsening diabetes.

"The FDA approval of this drug combination provides a hopeful step forward in the treatment of anaplastic thyroid cancer (ATC). Timely finding of the BRAF mutation in this subset of ATC patients remains a challenge, because it is a race for time to get BRAF-mutated patients onto these new treatments. It is also our hope that these patients will be managed at or in collaboration with centers with expertise in the treatment of ATC," said Gary Bloom, executive director of ThyCa, in an interview with CURE.