Amgen study shows platelets up with romiplostim
LOS ANGELES, Dec 10 (Reuters) - Amgen Inc (AMGN.O) said on Monday its experimental drug AMG 531 increased platelet production in adults with a bleeding disorder known as chronic immune thrombocytopenic purpura.
Results from the Phase 3 trial of the drug, also known as romiplostim, included 62 ITP patients and were presented at the American Society of Hematology's annual meeting in Atlanta.
Data from the Amgen-sponsored study showed that the trial met its primary endpoint with 61 percent of the 41 romiplostim-treated patients achieving durable platelet response, compared with just 5 percent of the 21 patients in the placebo arm.
Durable platelet response was 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, researchers said.
Overall response -- defined as either a durable response or a transient response of at least four weeks -- was nearly 88 percent in romiplostim-treated patients, compared with 14 percent of patients in the placebo group.
Researchers said the mean number of weeks with a platelet response was significantly greater in romiplostim-treated patients than in the placebo group at 15 weeks versus 1 week.
Across the study, 17 percent of the romiplostim-treated patients required rescue medications, such as corticosteroids, compared with 62 percent of placebo-treated patients.
Five serious adverse events were reported, none of which were deemed treatment-related.
The most commonly reported side-effects included muscle and joint pain, dizziness, fever, insomnia and diarrhea.
No patients tested positive for neutralizing antibodies against either AMG 531 or endogenous thrombopoietin, the major platelet growth factor promoting platelet production.
Amgen has asked regulators in the United States, European Union, Australia and Canada to approve AMG 531 as a treatment for adults with chronic ITP. Regulatory authorities in the United States, Australia and Canada have granted priority review of Amgen's application.
ITP is a disorder in which the immune system mistakenly targets blood platelets as foreign objects and destroys them. The platelets, which are needed for clotting, are eliminated by the spleen.
The disease can result in dangerously low platelet counts that may result in spontaneous bleeding or bruising.
There are an estimated 15,050 to 30,100 new cases of ITP in U.S. adults and children each year, based on a U.S. government population estimate and a disease prevalence estimate from the Annual Review of Medicine. Continued...
