FDA grants orphan drug status to Medarex's Valortim to treat anthrax infection

By E. Janene Geiss

Philadelphia, March 6 - Medarex, Inc. and PharmAthene, Inc. announced Monday that the Food and Drug Administration has granted orphan drug designation to Valortim (MDX- 1303) for the treatment of anthrax infection.

Valortim is an investigational fully human antibody created using Medarex's UltiMAb Human Antibody Development System that targets the Bacillus anthracis protective antigen, according to a company news release.

The U.S. Orphan Drug Act is intended to encourage companies to develop safe and effective therapies for the treatment of rare diseases and conditions, specifically those expected to affect fewer than 200,000 people in the United States. Orphan drug designation provides important benefits to companies such as eligibility for a special seven-year period of market exclusivity upon approval for the compound and indication with orphan designation, potential tax credits for research, potential grant funding for research and development, reduced filing fees for marketing applications, and assistance with clinical trial protocol review.

"Despite aggressive antibiotic therapy and supportive care, the anthrax attacks of 2001 resulted in a mortality rate of nearly 50%, illustrating the urgent need for more effective anthrax therapeutics," David P. Wright, president and chief executive officer of PharmAthene, said in the release.

"We believe Valortim may be the superior choice for procurement in the Strategic National Stockpile under Project BioShield. Its mechanism of action appears to work under the same mechanism as the natural protective response to anthrax vaccine yet Valortim has the potential to provide immediate immunity compared to vaccines, which may take months to confer immunity. Animal studies have demonstrated efficacy in both pre- and post-exposure prophylaxis and treatment for anthrax infection, potentially enabling therapeutic intervention after the appearance of disease symptoms, when antibiotic therapy is progressively less effective," Wright added in the release.

Valortim is being evaluated in a phase 1 open-label, dose-escalation clinical trial to evaluate the safety, tolerability, immunogenicity, and pharmacokinetics of a single dose of Valortim administered intravenously or intramuscularly in healthy volunteers.

Results from this trial are anticipated later this year.

Preclinical studies suggest that Valortim has the potential to provide significant protection against anthrax infection when administered prophylactically, or prior to the emergence of symptoms of anthrax infection and also may increase survival when administered therapeutically, or once symptoms become evident, officials said.

In these studies, Valortim has been shown to protect both rabbits and monkeys against the lethal effects of anthrax infection when administered at the time of exposure at doses as low as 1 mg/kg. When administered to rabbits after the development of symptoms, Valortim also improved survival as late as 48 hours post-exposure as compared to controls, officials said.

Valortim (MDX-1303) is a fully human antibody designed to protect against inhalation anthrax, the most lethal form of illness in humans caused by the bacillus anthracis bacterium. The investigational antibody is designed to target a protein component known as the anthrax protective antigen of the lethal toxin complex produced by the bacterium.

PharmAthene, a privately held biotechnology company in Annapolis, Md., was formed to meet the critical needs of the United States by developing biodefense products. It is dedicated to the rapid development of important and novel biotherapeutics to address biological pathogens and chemicals that may be used as weapons of bioterror.

Medarex is a Princeton, N.J., biopharmaceutical company focused on the development and potential commercialization of fully human antibody-based therapeutics to treat life-threatening and debilitating diseases, including cancer, inflammation, autoimmune disorders and infectious diseases. Medarex applies its UltiMAb technology and product development and clinical manufacturing experience to generate, support and potentially commercialize a broad range of fully human antibody product candidates for itself and its partners.

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