Tumor-starving pill helps thyroid cancer - study

WASHINGTON, July 2 (Reuters) - Amgen's (AMGN.O) once-a-day pill to starve tumors can help many patients with hard-to-treat thyroid cancer, either by shrinking tumors or slowing their growth, researchers reported on Wednesday.

And they found a marker -- a genetic clue -- that showed which patients were the most likely to be helped. This could offer a step to more tailored treatments, the researchers reported in the New England Journal of Medicine.

They said 49 percent of patients with advanced thyroid cancer responded to the pill, known as AMG 706 or motesanib diphosphate.

Of these, 14 percent saw their tumors shrink, and tumors did not grow for more than 24 weeks among 35 percent. On average, patients gained 40 weeks during which their cancer did not worsen.

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

"Finding that patients whose tumors bear a particular mutation were more likely to respond to the drug is an example of where we would like to head in our research," said Dr. Steven Sherman of the University of Texas M.D. Anderson Cancer Center in Houston, who helped lead the study.

"This is the first of the various thyroid cancer trials to identify specific mutations that might allow us to individualize or personalize therapy."

The researchers started with 93 patients, of whom 32 completed the full 48 weeks of treatment in the Phase 2 clinical trial. Thirty-five patients stopped because their cancer worsened, five died, and 12 pulled out because of adverse events, which included diarrhea, stroke and dangerously low calcium levels.

Sherman said the drug, which is also being tested against breast and lung cancer, may be worth the side-effects for people with thyroid cancer who have few other choices.

"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," he said.

In February, Amgen agreed to sell the rights for motesanib to Japan's Takeda Pharmaceutical Co Ltd (4502.T). The companies would split any profit 50-50 outside Japan.

More than 37,000 new cases of thyroid cancer will be diagnosed in the United States in 2008, according to the American Cancer Society, with 1,500 deaths.

(Reporting by Maggie Fox, editing by Will Dunham)