Votrient® (pazopanib) appears highly active against advanced, radioiodine-refractory differentiated thyroid cancer. These results were presented at the 14th International Thyroid Congress.
The thyroid is a gland in the throat that produces hormones mostly related to metabolic processes in the body. Overall, thyroid cancer is considered to be a highly curable cancer, with 97% of individuals alive at least five years following diagnosis. Nearly 95% of all thyroid cancers are classified as differentiated thyroid cancers; the distinction refers to the type and characteristics of the cancer cells.
Votrient is an oral medication known as a multi-targeted tyrosine kinase inhibitor. The drug may help slow or prevent angiogenesis (the growth of new blood vessels), which deprives the cancer of the oxygen and nutrients it needs to grow. Votrient is approved by the FDA for the treatment of advanced renal cell carcinoma (kidney cancer).
Advanced differentiated thyroid cancers have historically not responded to treatment with chemotherapy. It has been thought, however, that tyrosine kinase inhibitors, such as Votrient, may be effective in the treatment of this form of thyroid cancer, as tyrosine kinases have been implicated in the development of the disease.
To evaluate the effectiveness of Votrient in advanced, radioiodine-refractory differentiated thyroid cancer, researchers conducted a Phase II multicenter trial. Data were included from 37 patients who had received up to two prior therapies, had measurable disease, and whose disease had progressed in the six months before they were enrolled in the study. Patients received 800 mg of Votrient daily.
- Following a median of 12 four-week cycles of treatment with Votrient, there were 18 partial responses (PRs) to therapy.
- Researchers estimated that PRs would last for one year in 66% of patients.
- Median progression-free survival was 11.7 months.
- Overall survival at one year was 81%.
- When PR was measured according to thyroid cancer cell type, eight PRs were observed in11 patients with follicular cell type (72.7%), five PRs in 11 patients with Hürthle cell type (45.4%), and five PRs in 15 patients with papillary cell type (33.3%).
- 66.7% of patients who were antithyroidglobulin-negative (no antibodies to the protein thyroidglobulin, produced by the thyroid) experienced a decrease in thyroidglobulin of more than 30%.
- Side effects were modest, but 15 patients did require a dose reduction due to adverse effects. Frequent side effects included diarrhea and hypertension.
The researchers concluded that Votrient is highly active in advanced differentiated thyroid cancer and well tolerated; the drug may therefore be a promising treatment for patients with this disease. Votrient will be further evaluated in this patient population in an upcoming Phase III clinical trial.
Reference: Bible KC, Suman VJ, Molina JR, et at. Evidence of clinical efficacy of the multi-targeted tyrosine kinase inhibitor pazopanib in rapidly progressive radioiodine-refractory metastatic differentiated thyroid cancers: results of the Phase 2 consortium study MC057H. Presented at the 14th International Thyroid Congress, Paris, France, September 11-16, 2010. Abstract OC-022.
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