Thyroid Cancer Treatment Study-Mayo Clinic

The drug pazopanib may help revolutionize the care of patients with metastatic, rapidly progressive differentiated thyroid cancers, say researchers at Mayo Clinic who are publishing findings of a phase II clinical trial in Lancet Oncology. The researchers studied 37 patients with the most aggressive form of this cancer — developing in less than 5 percent of patients with differentiated thyroid cancer — and found that about half (18) patients had a long-lasting response to pazopanib. Of that group, 12 are still alive without disease progression. The median progression-free survival time was 11.7 months, with an overall survival rate of 81 percent at one year. The researchers say that, to their knowledge, these findings represent by far the highest response rate yet reported in such aggressive cases of differentiated thyroid cancer. They caution however, that this drug is not meant to be used in slow growing differentiated thyroid cancers and that they cannot assess the survival advantage pazopanib offers to the patients studied. Determining survival benefit would require a randomized clinical trial testing the agent, which inhibits all three vascular endothelial growth factor (VEGF) receptors, compared to other treatments or a placebo. “In this group of patients, we would have expected the cancer to have progressed in everyone within six months, but instead the median time to progression was almost a year in response to pazopanib therapy,” says Keith Bible, MD, Ph.D., a …