IMMUNO's IMMUNO-Ag rgp160 AIDS VACCINE READY FOR CLINICALS
IMMUNO's IMMUNO-Ag rgp160 AIDS VACCINE READY FOR CLINICALS as the sixth AIDS vaccine candidate to be approved for clinicals by FDA and the third vaccine incorporating the recombinant gp160 protein from the envelope of the AIDS virus. The Immuno Group will begin Phase I trials of the recombinant gp160 vaccine in 60 HIV-negative volunteers who are at low risk of infection with the AIDS virus, Martha Eibl, director of the company's AIDS vaccine research, announced at a Nov. 20 press conference in Washington, D.C. The vaccine is the product of a collaborative research and development agreement (CRADA) between The Immuno Group's Rochester, New York-based subsidiary Immuno-U.S., the National Institute of Allergy and Infectious Diseases, and the National Cancer Institute. The Immuno Group is based in Vienna, Austria. Immuno-Ag will be evaluated at five NIAID AIDS Evaluation Units in the U.S. The first phase of the trial will evaluate a 12.5 microgram dose given to 20 patients; 10 control patients will receive placebo. During the second phase, another 20 patients will receive a 50 mcg dose, with 10 additional patients receiving placebo. Clinical investigator Robert Belshe, MD, St. Louis University School of Medicine, explained at the press conference that during the Phase I trials, researchers will evaluate blood samples from inoculated patients to determine the quality of the antibodies produced and to evaluate the dosage in order optimize the immune response. Preliminary data could be available three to six months after the trials begin, Belshe said. In preclinical work, Immuno researchers developed and tested two versions of the vaccine, Eibl said. One vaccine used a lipid-based adjuvant and the other used a mineral carrier-based adjuvant. Each version was evaluated in two chimpanzees: the regimen included an initial shot and two boosters. Each vaccine was tested in one immunologically strong and one immunologically weak animal. According to Eibl, the stronger-responding chimpanzee that received the lipid-based vaccine has been protected from HIV infection for nearly three years, the longest known period of protection of any vaccine studied so far in animals, following challenge with 100 infectious doses. When the weaker-responding animal was similarly challenged, virus was recovered after the first nine months, Eibl said. In the mineral carrier arm of the chimp trials, both animals tolerated the vaccine well, but the response "was not sufficient to protect when challenged" with 100 infectious doses, Eibl explained. Both chimps were subsequently revaccinated with the lipid-based vaccine one year after viral challenge to determine whether the immune response to the mineral-based vaccine could be improved by boosting with a lipid-based formulation; results are yet to be determined. Immuno's candidate vaccine for clinical trials uses the same antigen that is present in the lipid-based formula in a mineral carrier formulation. The goal of the Phase I trial is to assess whether the degree of immunity achieved in the chimps immunized with the mineral carrier-based formulation can be achieved in humans. The study will also evaluate the effect of additional vaccination procedures to see if they elevate the degree of immunity.
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