Pazopanib Shows Promise for Advanced Thyroid Cancer in Phase II Trials
According to the US Centers for Disease Control and Prevention, about 37,000 Americans are diagnosed with thyroid cancer each year, and the incidence has doubled over the past ten years. About 5 percent of patients develop and aggressive life-threatening form of the disease with few treatment options. In a Phase II clinical trial, researchers from the Mayo Clinic have found that a drug called Pazopanib helps to shrink tumors for as much as one year.
Pazopanib Already Approved for Kidney Cancer
The Mayo Clinic team studied the effects of pazopanib in 37 trial participants, all with rapidly progressing thyroid cancer. 18 of them, or 49%, responded positively to the therapy – tumors shrank 30% or more - and in at least two-thirds the response was estimated to last longer than one year. The results are published in the journal The Lancet Oncology.
Thyroid cancer is a cancerous growth of the thyroid gland, one of the largest endocrine glands in the body. Locatedd in the lower part of the neck, the gland makes and stores hormones that regulate heart rate, blood pressure, body temperature, and the rate at which food is converted into energy.
People who have had radiation therapy to the neck are at a higher risk of developing thyroid cancer. This type of therapy was common in the 1950s when children received radiation to treat enlarged thymus glands, adenoids, tonsils, and skin disorders. Family history, chronic goiter and diseases such as Hashimoto’s thyroiditis and Cowden’s syndrome are also risk factors.
Thyroid cancer can affect both men and women, but women comprise approximately 75% of all cases.
Pazopanib is an antiantiogenetic drug that works by targeting protein receptors involved in the growth of new blood vessels that help the tumor grow and spread. The drug, marketed under the brand name Votrient, is already approved by the FDA for treating advanced kidney cancer. Side effects from the treatment caused diarrhea, raised blood pressure (hypertension), and a higher concentration of aminotransferase, an enzyme found primarily in cells of the liver and heart.
Phase III trials should start soon, according to the study authors. If approved, the drug will be taken once daily, however will likely be an expensive therapy. The US Department of Health and Human Services estimates that therapy with pazopanib will likely cost about $6,595 a month.
Bible K, et al "Efficacy of pazopanib in progressive, radioiodine-refractory metastatic differentiated thyroid cancers: results of a phase 2 consortium study" Lancet Oncol 2010; DOI: 10.1016/S1470-2045(10)70203-5.
Schlumberger M "Kinase inhibitors for refractory thyroid cancers" Lancet Oncol 2010; DOI: 10.1016/S1470-2045(10)70226-6.