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Amgen thyroid drug succeeds in late stage kidney patient trial

July 17 (Reuters) - An experimental drug to reduce excess parathyroid hormone levels in patients with chronic kidney disease succeeded in meeting the primary and secondary goals of a Phase III study, Amgen Inc said on Thursday.

More than 75 percent of patients who received the drug, AMG 416, saw their parathyroid hormone levels drop by more than 30 percent, compared with 9.6 percent who experienced a similar reduction among those who got a placebo.

The result of the 515-patient, 26-week study was deemed to be statistically significant, Amgen, the world's largest biotechnology company, said.

Amgen obtained AMG 416 through its acquisition of Kai Pharmaceuticals in 2012.

Secondary hyperparathyroidism (SHPT) is a serious condition that often progresses among patients with chronic kidney disease who are receiving dialysis. It develops as a response to declining kidney function when the parathyroid glands increase the production of the hormone.

AMG 416, which is administered intravenously, works by binding to and activating the calcium-sensing receptor on the parathyroid gland.

Secondary goals of the study included the percent change from baseline in serum phosphorus concentration between weeks 20 and 27, and corrected calcium concentration. In both cases, AMG 416 achieved statistically significant improvements compared with placebo, Amgen said.

The rate of side effects reported during treatment was high for both groups, occurring in 91.7 percent of the AMG 416 patients and 81.1 percent among the placebo group. These included blood calcium reductions, diarrhea and muscle spasms.

Adverse side effects deemed to be serious were reported in 24.6 percent and 27.4 percent of patients who received AMG 416 and placebo, respectively.

"We are encouraged by the results of this study and look forward to sharing results from a second placebo-controlled study later this year," Amgen research chief Sean Harper said in a statement.

(Reporting by Bill Berkrot; Editing by Tom Brown)