A combination of the drugs pazopanib and paclitaxel shows promise in slowing anaplastic thyroid cancer (ATC), according to a new study in Science Translational Medicine (January 2, 2013, Vol. 5:166, p. 166ra3).
The two drugs together resulted in greater anticancer activity in ATC than either drug alone, lead researcher Keith Bible, MD, PhD, a Mayo Clinic oncologist, noted in a press release.
Anaplastic thyroid cancer is a rare but aggressive form that is resistant to most therapies; it typically strikes men and women in their 60s and 70s. Pazopanib, a kinase-inhibitor that interferes with the growth of cancer cells, is already approved by the U.S. Food and Drug Administration (FDA) to treat renal cancer tumors. Paclitaxel is an FDA-approved chemotherapy drug that disrupts cell division.
The researchers studied ATC cells and tumors in cell cultures and animal models. They found that human ATC cells were readily killed and ATC tumors implanted into mice were 50% smaller when treated with the combination, compared with treatment with either drug alone. Pilot therapy of one patient with metastatic ATC using the combination also resulted in marked tumor shrinkage lasting more than six months.
The researchers characterized the findings as "highly unexpected" for this type of aggressive tumor, which can often double in size in a matter of days.
