Final results from largest phase 3 open-label study assessing Nplate®

Amgen today announced that data from several key Nplate® (romiplostim) studies were presented at the 53rd Annual Meeting and Exposition of the American Society of Hematology (ASH), Dec. 10-13, 2011, in San Diego. Of note, final results from the international, Phase 3, open-label, single-arm ‘209 study evaluating the safety and efficacy of Nplate in adults with primary immune thrombocytopenia (ITP) demonstrated that Nplate induced a rapid platelet response in adult ITP patients with low platelet counts or bleeding symptoms and maintained a consistent safety profile (Abstract No. 3279).

In the study, incidence and type of adverse events (AEs) in patients treated with Nplate were consistent with those reported in previous studies. The most common side effects included headache, arthralgia and fatigue.

Approximately 90 percent of patients achieved each of the platelet response definitions, regardless of splenectomy status. Median time to response was one to two weeks. Over the course of the study, a doubling of the platelet count to greater than or equal to 50,000 platelets per microliter was achieved by 91 percent of patients who received Nplate. A platelet count increase of greater than or equal to 20,000 platelets per microliter from baseline was achieved by 93 percent of patients who received Nplate.

“We are very pleased to present the final results from the largest prospective study of Nplate in adult patients with primary ITP, which highlight Nplate’s ability to successfully treat these patients,” said Sean E. Harper, M.D., senior vice president of Global Development and chief medical officer at Amgen. “Additional data presented at the meeting in other disease states help further elucidate the safety and efficacy profile of Nplate. Collectively, these data help build upon our understanding of Nplate’s treatment potential for patients with thrombocytopenia.”

‘209 Study Design

This was an open-label, single-arm study of Nplate for the treatment of adults with primary ITP. Nplate was administered once weekly, with dose adjustments to maintain platelet counts of greater than or equal to 50,000 platelets per microliter. The primary study objective was incidence of AEs and antibody formation. Secondary study objectives were to evaluate platelet responses defined as either (1) doubling of baseline count and a platelet count greater than or equal to 50,000 platelets per microliter or (2) a platelet count increase of greater than or equal to 20,000 platelets per microliter from baseline. Four hundred and seven patients were enrolled; median on-study treatment duration was 44 weeks. Fifty-one percent of patients had previously undergone splenectomy.

Abstracts are available on the ASH website at www.hematology.org and updated data were presented at the meeting. All presentations will take place at the San Diego Convention Center unless noted otherwise.