The FINANCIAL — Amgen Inc. (Nasdaq: AMGN) on December 6 announced results from three studies on the safety and efficacy of Nplate?? (romiplostim) in adult patients with myelodysplastic syndromes (MDS).
MDS is a pre-leukemic condition in which early blood forming cells in the bone marrow are unable to mature normally, thereby limiting their ability to produce normal mature blood elements, which can lead to low platelet counts. The results of the studies were presented at the 2009 American Society of Hematology (ASH) Annual Meeting and Exposition (ASH Abstracts #1769, #1770 and #2765).
Interim Results from Long-Term Open-Label Extension Study of Nplate in MDS (Abstract #2765)
The ongoing, open-label extension study was designed to evaluate the safety and efficacy of Nplate in lower risk MDS patients. The primary endpoints of the interim study for presentation at ASH evaluated adverse event rates with long-term use of Nplate and incidence of antibody development to Nplate and/or thrombopoietin (TPO). Secondary endpoints evaluated the incidence of bleeding events and platelet response during the study period.
Nplate was generally well-tolerated, with the majority of patients (n=28) achieving a platelet response (61 percent) for eight or more consecutive weeks. The primary endpoint evaluating adverse event rates was met, with most patients experiencing adverse events that were mild to moderate with the most common being epistaxis (36 percent), arthralgia (29 percent), anemia (21 percent) and cough (21 percent). The co-primary endpoint was also met, as no neutralizing antibodies to Nplate or TPO were observed, nor progression to acute myeloid leukemia (AML). In addition, no cases of bone marrow fibrosis were reported.
Results for the secondary endpoint showed that 64 percent of patients (n=18) reported one or more bleeding events and 21 percent of patients (n=6) reported one or more clinically significant bleeding events. In the study, 29 percent of patients (n=8) received platelet transfusions. Frequency of bleeding events and platelet transfusions decreased over time. Bleeding events were evaluated on Common Terminology Criteria for Adverse Events (CTCAE) grades one to four, and clinically significant bleeding events were evaluated on CTCAE grades three and over, serious adverse events or any bleeding adverse event requiring intervention.
The data also showed that Nplate was effective with over half (54 percent) of patients (n=28) achieving a platelet response by week three and 61 percent achieving a durable platelet response overall (for eight or more consecutive weeks), meeting the additional secondary endpoint. Platelet response was defined as an absolute platelet increase of greater than or equal to 30,000 platelets per microliter for patients starting with less than 20,000 platelets per microliter, or an increase from less than 20,000 platelets per microliter to over 20,000 platelets per microliter and by at least 100 percent. The study showed that 82 percent of patients (n=28) had a platelet response and the median platelet response lasted 30 weeks.
"Both the safety and efficacy data are important given the limited treatment options available for those who suffer from low platelet counts due to MDS," said Dr. Hagop Kantarjian, Professor of Medicine and Chairman of the Department of Leukemia at The University of Texas M.D. Anderson Cancer Center.
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