Soligenix receives European, Canadian patents for its ricin toxin vaccine (RiVax) formulation

Posted on Friday, 13th July 2018 @ 04:53 PM by Text Size A | A | A

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Soligenix, Inc., a late-stage biopharmaceutical company, announced that it has received notice of allowance for European and Canadian patent applications further extending protection around ThermoVax  including coverage of the company’s ricin toxin vaccine, RiVax. RiVax potentially would be added to the Strategic National Stockpile and dispensed in the event of a terrorist attack.

Soligenix, Inc., a late-stage biopharmaceutical company, announcedthat it has received notice of allowance for European and Canadian patent applications further extending protection around ThermoVax  including coverage of the company’s ricin toxin vaccine, RiVax. ThermoVax is a proprietary vaccine heat stabilization platform technology and the patent, titled “Thermostable vaccine compositions and methods of preparing same,” has been previously allowed in Japan, Australia and New Zealand with applications pending in China, United States, and other jurisdictions.

The company notes that the issued patent is complementary to previous patents, including U.S. patents 8,444,991 granted on 21 May 2013 and 8,808,710 granted on 19 August 2014, which include claims for methods of making stabilized vaccines and their attendant compositions. In this new patent, the main claims cover formulations of Soligenix’s proprietary thermostabilized ricin toxin vaccine, RiVax. The thermostable formulation of RiVax has been shown to be stable for at least 12 months at temperatures up to 40 degrees Celsius (104 degrees Fahrenheit) and to provide 100 percent protection to non-human primates exposed to aerosol ricin challenge in preclinical studies.

Recent developments in the RiVax program have also described immune correlates of protection for the ricin toxin vaccine, which are important to facilitating potential approval of thermostabilized RiVax via the U.S. Food and Drug Administration (FDA) “Animal Rule.” As a biodefense vaccine, RiVax also has the potential to qualify for a priority review voucher (PRV) upon FDA approval. Recent PRVs have sold for as much $350 million.

“Soligenix continues to advance its RiVax program with funding from the U.S. government.” stated Christopher J. Schaber, President and Chief Executive Officer of Soligenix. “Soligenix is a world leader in ricin toxin vaccine development, with a Phase 2 clinical trial planned to begin this year.”

About ricin toxin
Ricin toxin is a lethal plant-derived toxin and potential biological weapon because of its stability and high potency, and the fact it is readily extracted from by-products of castor oil production. Ricin comes in many forms including powder, mist or pellet. Ricin can also be dissolved in water and other liquids. The U.S. Centers for Disease Control and Prevention estimates that the lethal dose in humans is about the size of a grain of salt. Ricin toxin illness causes tissue necrosis and general organ failure leading to death within several days of exposure. Ricin is especially toxic when inhaled. Ricin works by entering cells of the body and preventing the cells from making

the proteins it needs. Without the proteins, cells die, which is eventually harmful to the entire body.

There are currently no effective treatments for ricin poisoning. The successful development of an effective vaccine against ricin toxin may act as a deterrent against the actual use of ricin as a biological weapon and could be used to vaccinate military personnel and civilian emergency responders at high risk of potential exposure in the event of a biological attack.

About RiVax
RiVax is Soligenix’s proprietary heat stable recombinant subunit vaccine developed to protect against exposure to ricin toxin. With RiVax, Soligenix is a world leader in the area of ricin toxin vaccine research.

RiVax contains a genetically altered version of a Ricin Toxin A (RTA) chain containing two mutations that inactivate the toxicity of the ricin molecule. A Phase 1A clinical trial was conducted with a formulation of RiVax that did not contain an adjuvant. This trial revealed dose dependent seroconversion as well as lack of toxicity of the molecule when administered intramuscularly to human volunteers. The adjuvant-free formulation of RiVax induced toxin neutralizing antibodies that lasted up to 127 days after the third vaccination in several individuals.

To increase the longevity and magnitude of toxin neutralizing antibodies, RiVax was subsequently formulated with an adjuvant of aluminum salts (known colloquially as Alum) for a Phase 1B clinical trial. Alum is an adjuvant that is used in many human vaccines, including most vaccines used in infants. The results of the Phase 1B study indicated that Alum-adjuvanted RiVax was safe and well tolerated and induced greater ricin neutralizing antibody levels in humans than adjuvant-free RiVax. In preclinical animal studies, the Alum formulation of RiVax also induced higher titers and longer-lasting antibodies than the adjuvant-free vaccine.  Vaccination with the thermostabilized Alum-adjuvanted RiVax formulation in a large animal model provided 100 percent protection (p<0.0001) against acute exposure to aerosolized ricin, the most lethal route of exposure for ricin. The protected animals also had no signs of gross lung damage, a serious and enduring ramification with long-term consequences for survivors of ricin exposure.  These results are described in a publication available here.

Heat stabilization of RiVax is achieved with the Company’s proprietary ThermoVax technology, designed to eliminate the cold-chain production, distribution and storage logistics required for most vaccines. The technology utilizes precise lyophilization of protein immunogens with conventional aluminum adjuvants in combination with secondary adjuvants for rapid onset of protective immunity with the fewest number of vaccinations. By employing ThermoVax during the final formulation of RiVax, the vaccine has demonstrated enhanced stability and the ability to withstand temperatures at least as high as 40 degrees Celsius (104 degrees Fahrenheit) for up to one year.

The development of RiVax has been sponsored through a series of grants from both National Institute of Allergy and Infectious Diseases (NIAID), and the FDA and ongoing development is sponsored by NIAID contract. The Phase 2 clinical trial planned for the second half of 2018 is contingent upon exercise of the final option by the U.S. government under NIAID contractor through other funding sources. RiVax potentially would be added to the Strategic National Stockpile and dispensed in the event of a terrorist attack. RiVax has received orphan drug designation in the United States and in Europe.

As a new chemical entity, an FDA approved RiVax vaccine has the potential to qualify for a biodefense PRV, which allows the holder accelerated review of a drug application. Approved under the 21st Century Health Cures Act in late 2016, the biodefense PRV is awarded upon approval as a medical countermeasure when the active ingredient(s) have not been otherwise approved for use in any context. PRVs are transferable and can be sold, with sales in recent years ranging between $125 million to $350 million. When redeemed, PRVs entitle the user to an accelerated review period of six months, saving a median of seven months’ review time as calculated in 2009. However, the FDA must be advised 90 days in advance of the use of the PRV and the use of a PRV is associated with an additional user fee ($2.7 million in 2017).

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