Soligenix, Inc. (Soligenix or the Company) (OTC Bulletin Board: SNGX), a late-stage biopharmaceutical company, reported today that it has completed enrollment of its Phase 1B clinical trial of RiVax™, a ricin subunit vaccine, in healthy volunteers. Preliminary results indicate that RiVax™ appears safe at all doses tested in volunteers. This trial is designed to assess the duration of immune responses using an adjuvant formulation of RiVax™ over a period of more than one year after vaccination.
This ongoing Phase 1B trial is intended to evaluate the safety and immunogenicity of an improved formulation of RiVax™ containing an adjuvant and is anticipated to result in longer lasting and higher levels of protective antibodies. The current trial employs an escalating dose strategy in which volunteers receive three intramuscular doses of vaccine at six-week intervals, matching many commonly employed vaccination regimens. The trial is being funded by a grant from the FDA's Orphan Products Division. The principal investigator of the study is Ellen Vitetta, PhD, Director of the University of Texas Southwestern Medical Center's Cancer Immunobiology Center. Analysis of human immunogenicity and complementary non-human primate efficacy is expected during the first half of 2011.
RiVax™ safety and immunogenicity has previously been observed in a Phase 1 clinical trial of the subunit vaccine without an adjuvant. Results demonstrated that the adjuvant-free RiVax™ was well tolerated and induced antibodies in humans that neutralized ricin toxin in tissue culture and in mice. Serum antibodies that neutralize ricin are expected to function to reduce mortality and morbidity from exposure to ricin, including the aerosol route. The new formulation employs a well characterized adjuvant to induce protective, neutralizing antibodies in humans.
"We are very encouraged that we have demonstrated safety at the highest vaccine doses in the current trial volunteers," said Dr. Vitetta. "This study with the adjuvanted formulation will further guide us in determination of safe dose levels of RiVax™ that induce the highest levels of antibodies that are correlated to efficacy. We are looking forward to completing the analysis of the immune responses induced by RiVax™ in the sera of volunteers up to one year after the last vaccination."
"We are anticipating that the adjuvant form of the vaccine will induce antibodies in humans that are correlated with long-term immunity to ricin toxin," said Robert N. Brey, PhD, Chief Scientific Officer of Soligenix. "We are concurrently validating those immunological correlates in animal model systems with our team of collaborators."
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