Claim covers the technology that describes the derivation of the ricin A chain antigen.

DOR BioPharma’s patent related to its ricin toxin vaccine was approved. This patent includes methods of use and composition claims for RiVax™, its lead biodefense product. “We continue to be excited about developing a ricin vaccine to protect against the potential use of ricin toxin as a biological weapon,” says Christopher J. Schaber, president and CEO.

With 49 claims, the allowed patent covers the technology that describes the derivation of the ricin A chain antigen, which constitutes the immunogenic component of RiVax. It is a vaccine that contains a recombinant subunit of the A chain of ricin toxin, which induces ricin neutralizing antibodies in humans and animals. 

DOR exclusively licensed worldwide rights to the patent from the University of Texas Southwestern Medical Center at Dallas (UTSW) for the production, sales, and marketing of RiVax. Schaber points out that the technology developed at UTSW for RiVax is considered the strongest in this area.

U.S. Patent Application #09/698,551 was titled “Ricin A chain mutants lacking enzymatic activity as vaccines to protect against aerosolized ricin.” The allowed claims in the patent application include the combination of specific mutations in the enzymatically active site of ricin A chain with specific mutations in the site that induces vascular leak syndrome (VLS). The combination of mutations in each of the key sites for ricin toxicity ensures that the recombinant subunit is inherently safe, explains DOR. Studies conducted by Ellen Vitetta, Ph.D., director of the cancer immunobiology center at UTSW and her colleagues have indicated that the specific mutations introduced into the ricin A chain eliminate the toxic activity of the molecule but do not alter the structure, permitting a highly immunogenic and safe vaccine.

RiVax was shown to be safely tolerated in humans in a Phase I dose-escalating trial conducted last year and did not result in any side effects. Even without an adjuvant, RiVax induced antibodies in all five of the individuals who received the highest dose, four out of five who received the intermediate dose, and one out of five who received the lowest dose levels, DOR reports.

“We expect that the introduction of a safe and effective ricin vaccine will be a step forward in the national effort to develop effective countermeasures and therapies for significant biothreats and emerging pathogens,” remarks Schaber.

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