Blood vessel inhibitor shows promise against metastatic thyr...( HOUSTON - Thyroid cancer that has sp...),Health

HOUSTON - Thyroid cancer that has spread to distant sites has a poor prognosis, but an experimental drug that inhibits tumor blood vessel formation can slow disease progression in some patients, a research team led by investigators from The University of Texas M. D. Anderson Cancer Center reports in the July 3rd edition of The New England Journal of Medicine.

The investigational drug, motesanib diphosphate, is a VEGF inhibitor, a biologic agent that targets receptors on a protein known as vascular endothelial growth factor (VEGF). VEGF is instrumental in angiogenesis (formation of new blood vessels), a process that allows tumors to grow and spread.

Study lead author Steven I. Sherman, M.D., chair and professor of M. D. Anderson's Department of Endocrine Neoplasia and Hormonal Disorders, noted strong evidence that VEGF receptors play an important role in metastatic thyroid cancer, a disease with few treatment options.

"There is no standard accepted chemotherapy for advanced metastatic differentiated thyroid cancer, and response rates have typically been 25 percent or less," Sherman said. "Most patients are not treated with systemic chemotherapy because the limited benefit rarely justifies the side effects. Treatment of thyroid cancer has been a completely unmet need."

Sherman, colleagues in 10 countries, and scientists from Amgen, which is developing motesanib diphosphate (AMG 706), planned and conducted one of the largest clinical trials ever done for metastatic thyroid cancer.

Of the 93 patients with rapidly progressing cancer who were enrolled in the study, 49 percent had a positive response. From that group 14 percent had their tumors shrink and 35 percent had their tumors stabilize for more than 24 weeks. Median progression-free survival was estimated to be 40 weeks.

Genetic analyses of 25 patients indicated that those with a specific mutation known as BRAF V600E in their tumors had a better
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