Neurobiological Technologies, Inc. Presents Dosing Rationale for Viprinex(TM) (ancrod) at the European Stroke Conference
Wednesday May 14, 8:15 am ET
NICE, France, May 14 /PRNewswire-FirstCall/ -- Neurobiological Technologies, Inc. (NTI®) (Nasdaq: NTII - News) reported for the first time at the European Stroke Conference detailed analyses supporting the dosing regimen in NTI's two ongoing Phase 3 studies of Viprinex(TM) (ancrod) for ischemic stroke. The company also provided information as to why it believes these studies are more likely to be successful in treating ischemic stroke than previous Phase 3 clinical trials conducted by others using the same snake venom-derived agent.
David E. Levy, M.D., Vice President, Clinical Development at NTI, presented his retrospective analysis of data from the prior North American and European Phase 3 stroke trials of Viprinex involving more than 1,700 patients. Viprinex has been shown to rapidly reduce blood levels of fibrinogen, an important agent involved in blood clotting and blood viscosity. Elevated fibrinogen levels are a risk factor for stroke and may be associated with greater stroke disability. Prior studies with Viprinex that target fibrinogen have shown a benefit from this approach.
"The prior studies of Viprinex showed improved efficacy, but used a dosing regimen that infused the drug over five to seven days, which kept fibrinogen levels low for too long, compromising safety," said Dr. Levy, the key presenter. "NTI has changed the treatment paradigm to a single, three-hour intravenous dose designed to reduce fibrinogen levels quickly, while avoiding the prolonged low fibrinogen levels that were tried previously. Stopping the infusion after three hours permits fibrinogen to return to normal levels much faster than when the drug is given over five to seven days."
Dosing in the successful North American Phase 3 trial was compared to dosing in the unsuccessful European Phase 3 trial. The analyses showed that European patients initially infused with Viprinex at the most rapid rate had statistically significant efficacy with Viprinex versus placebo. The analysis also showed that patients across both studies whose mean fibrinogen levels were kept above a certain threshold over the entire five to seven day treatment period had a rate of symptomatic intracranial hemorrhage that was substantially lower than in those with lower mean fibrinogen levels over the same five to seven day period. These data suggest that rapid initial lowering of fibrinogen is associated with better efficacy, but for safety purposes fibrinogen should be allowed to return back up to its higher level after treatment.
"Viprinex, a novel Fibrinogen Reducing Agent, is an enzyme that reduces levels of fibrinogen, the primary protein involved in blood clotting," said Warren W. Wasiewski, M.D., Vice President and Chief Medical Officer of Neurobiological Technologies, Inc. and a second author of the retrospective analysis. "Reducing fibrinogen in the blood lowers blood viscosity, which may improve blood flow. Additionally, as the fibrinogen is broken down, natural mechanisms are activated to dissolve blood clots that have already formed. Since Viprinex acts in the blood for a longer period of time than existing therapies for treatment of stroke, the effect of Viprinex on brain blood flow should be sustained longer. We believe that a single infusion of Viprinex would be better than a prolonged infusion for treating ischemic stroke."
Previous studies have shown that Viprinex can be effective when administered up to six hours after the onset of stroke symptoms, which could significantly expand the number of people who can be treated. The only currently approved drug therapy for ischemic stroke is limited to a three-hour window.
With more than 700,000 patients experiencing stroke each year in the United States, and existing therapies limited to the first three hours after onset of stroke symptoms, there is a substantial unmet medical need to increase treatment options that are safe and effective to more stroke patients.
The Ancrod Stroke Program I and II studies are Phase 3 clinical trials currently underway at sites in the United States, various European countries, Russia, Australia, New Zealand, South Africa, Israel and Taiwan.
surf's up......crikey
