Soligenix, Inc. has initiated a next generation anthrax vaccine development programme pursuant to a field-exclusive option agreement with Harvard University to negotiate a license under patent rights that cover prophylactic uses of a modified anthrax toxin protein. Initial development work will be covered pursuant to a previously issued $9.4 million National Institute of Allergy and Infectious Disease (NIAID) grant enabling development of thermo-stable ricin and anthrax vaccines.
Anthrax is an acute infectious disease that is easily transmitted to humans by environmentally durable spores that are produced by Bacillus anthracis. Because the spores are robust and contagious, anthrax is considered a Category A bioterror threat.
The option encompasses an issued US patent that covers engineered variants of protective antigen (PA) developed in the Harvard Medical School laboratory of Dr. John Collier. PA is the principal determinant of protective immunity to anthrax. Soligenix believes that it will be able to develop the Collier anthrax vaccine with an efficacy profile superior to other anthrax vaccines.
There has been a major effort on the part of the federal government to develop improved vaccines for use both pre- and post anthrax exposure. The vaccine currently in use, known as AVA (anthrax vaccine adsorbed), consists of a defined, but impure, mixture of bacterial components. AVA is FDA approved, but requires multiple injections followed by annual boosters. Vaccines such as AVA or others based on purified, native recombinant PA (rPA) sequences induce antibodies that neutralize anthrax holotoxin and can strongly protect animals from inhaled anthrax spores. To date, the government has funded more than $4 billion in anthrax vaccine development and commercial contracts.
“We are pleased to secure from Harvard option rights under the patent that covers this promising anthrax vaccine and to initiate its development under our existing grant funding,” stated Christopher J. Schaber, PhD, president and CEO of Soligenix. “We believe that the engineered PA variants can be used in platform technologies for delivery of single use or combination biodefense vaccines and will be useful for generating stable vaccines that induce antibodies in fewer doses than the conventional AVA or other rPA vaccines currently under development. Another significant improvement for stockpiled vaccines we intend to focus on would be extended stability relative to conventional vaccines. If long-term stability were achieved, the vaccine would have the potential to be stockpiled for general use and for post-exposure prophylaxis. We also envision expanding our thermostability technology into development of countermeasures against other more common infectious diseases.”
Anthrax infection can occur in three forms: cutaneous (skin), inhalation, and gastrointestinal. Inhaled spores can cause a rapidly progressing form of anthrax since the spores are transported to lymph nodes near the lungs where they germinate, releasing vegetative bacteria into the bloodstream. Bacteria synthesize a complex series of toxin components that make up anthrax toxin, resulting in overwhelming toxemia that causes shock and organ failure. Treatment of anthrax involves long-term antibiotic therapy, since ungerminated spores can lie dormant in the lungs for up to 60 days. Only a few inhaled spores can cause inhalational anthrax. Once the toxin has entered the bloodstream, antibiotics are ineffective, and only toxin-specific therapy is effective. Passively transferred antibodies can neutralize anthrax toxins and can be used post-exposure in conjunction with antibiotics. Because of the long residence time of spores in the lung, it is possible to vaccinate post-exposure, but the onset of neutralizing antibodies must occur during the period of antibiotic therapy.
Soligenix is a development stage biopharmaceutical company developing products to treat life-threatening side effects of cancer treatments and serious gastrointestinal diseases, and vaccines for certain bioterrorism agents.