Soligenix, a development-stage biopharmaceutical company, has released results from pre-clinical studies of its proprietary vaccine thermostabilization technology indicating that Soligenix is able to produce stable vaccine formulations using adjuvants, protein immunogens and other components that ordinarily would not withstand long temperature variations exceeding customary refrigerated storage conditions.
These studies were conducted with Soligenix's aluminum-adjuvanted ricin toxin vaccine, RiVax, made under precise lyophilization conditions using excipients that aid in maintaining native protein structure of the ricin A chain, the immunogenic compound of the vaccine. The ricin A chain is extremely sensitive to temperature and rapidly loses the ability to induce neutralizing antibodies when exposed to temperatures higher than 8 degrees C.
When RiVax was kept at 40 degrees C for over one month, all of the animals vaccinated with the lyophilized RiVax vaccine developed potent and high titer neutralizing antibodies. In contrast, animals that were vaccinated with the liquid RiVax vaccine kept at 40 degrees C did not develop neutralizing antibodies and were not protected against ricin exposure.
"We are very excited about these results as the achievement of extended stability under elevated temperature represents a significant step forward in vaccine technology," stated Robert N. Brey, PhD, chief scientific officer of Soligenix. "These studies successfully establish the proof of concept that our vaccine thermostabilization technology works and now allows for the potential to apply this technology to other conventional vaccines that require refrigeration…. Further, lack of long-term stability is a significant problem in vaccines for use in emergency situations and especially for vaccines used in the developing world where the cold storage chain is difficult to maintain. We believe that this technology has the potential to add value to many existing and developing vaccines."
The removal of water from pharmaceutical preparations by lyophilization is often used to confer extended shelf life to therapeutic protein products, but vaccines often lose potency during lyophilization, especially if they are formulated with aluminum salt adjuvants that are commonly used in vaccines. Therefore, most aluminum-adjuvanted vaccines must be refrigerated or frozen because of the sensitivity of vaccine components to room temperature or higher.
The World Health Organization (WHO) reports that 50% of all global vaccine doses are wasted because vaccines are not kept within required temperature ranges.
Soligenix has been developing its thermostabilization technology under a license agreement from the University of Colorado that was initiated to support the technology development efforts funded by a $9.4 million grant from the National Institute of Allergy and Infectious Diseases (NIAID). The license agreement has an expanded scope for thermostable vaccines for biodefense as well as all potential vaccine indications.