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June 2, 2007
A new study shows that the experimental drug axitinib slows tumor growth and/or shrinks tumors in patients with advanced thyroid cancer. Axitinib blocks receptors of vascular endothelial growth factor (VEGF), which plays a role in tumor formation by promoting the growth of blood vessels. Axitinib is a pill that can be taken by mouth.
The standard treatment for thyroid cancer is surgery and/or radioactive iodine, which cures a large percentage of patients, but few treatments are available for patients who can't be treated with these methods.
This phase II clinical trial followed 60 patients with thyroid cancer that had advanced despite other treatments. The tumors shrank by 31% to 68% in 22% of patients. This tumor shrinkage lasted from one to 16 months. The tumors stopped growing in another 50% of patients.
"Axitinib and other VEGF inhibitors represent an exciting new front in the treatment of advanced thyroid cancer," said Ezra Cohen, MD, Assistant Professor of Medicine at the University of Chicago and the study's lead author. "As recently as three years ago we had very little to offer these patients, and now we're seeing response rates at a level we've never seen with chemotherapy."
The most common side effect of axitinib was fatigue (extreme tiredness), experienced by 43% of patients. Serious side effects were low and included high blood pressure (7%) and protein in the urine (5%).
What This Means for Patients
This study suggests that axitinib may be an important treatment for patients with advanced thyroid cancer. Additional clinical trials are being planned, including a phase II clinical trial for cancer that is no longer responding to doxorubicin (Adriamycin, Rubex) and a phase III clinical trial for patients with specific subtypes of thyroid cancer. At this time, axitinib is only available as part of a clinical trial.