CORRECTED-Amgen study shows romiplostim boosts platelets

(Corrects last paragraph to show range of new cases)

By Lisa Baertlein

LOS ANGELES, Dec 8 (Reuters) - Amgen Inc (AMGN.O: Quote, Profile, Research, Stock Buzz) said on Saturday that a late-stage trial of its experimental drug AMG 531 showed it boosted and sustained platelet counts in adults with chronic immune thrombocytopenic purpura, a bleeding disorder.

The Phase 3 Amgen-sponsored trial included 63 chronic ITP patients, who had their spleens removed after other treatments had failed.

The results, presented at the American Society of Hematology's annual meeting in Atlanta, showed that 38 percent of the 42 patients who received AMG 531, also known as romiplostim, achieved a durable platelet response. There were no responses among the 21 patients who received the placebo.

Researchers also said that AMG 531-treated patients who were also taking ITP medications such as corticosteroids were able to reduce or discontinue use of those medications.

Researchers said the study met its primary endpoint of durable platelet response, defined as a platelet count of greater than or equal to 50,000 platelets per microliter for six of the final eight weeks of the 24-week treatment period.

None of the patients included in the durable response group received rescue medications, such as the corticosteroids, researchers said.