A vaccinia-based AIDS vaccine has proved safe in a Phase Iclinical trial, according to a report in an issue of The Lancet, tobe published tomorrow. However, the trial results indicatedthat the vaccine would be effective only in patients who hadnever been exposed to a vaccinia vaccine.

Vaccinia vaccines are commonly used for smallpoximmunization.

Collaborators at Bristol-Myers-Squibb Co. and its Seattle-basedsubsidiary, Oncogen Corp., reported that Bristol's recombinantvaccinia vaccine, HIVAC-1e, was safe and effective at inducingan immune response in healthy volunteers.

The study included 35 healthy, sero-negative volunteers, 31 ofwhom (termed primed patients) had previously beenvaccinated for smallpox with a vaccinia vaccine. The remainingfour patients, termed vaccinia-naive, had not been previouslyexposed to vaccinia. Half of the study group was vaccinatedwith a standard vaccinia vaccine. The other half received theBristol AIDS vaccine, consisting of a vaccinia virus engineeredto contain the gene encoding the gp160 envelope protein of theAIDS virus, HIV (human immunodeficiency virus).

The naive patients developed strong and persistent immuneresponses to both the vaccinia vaccine and the recombinantAIDS vaccine, including a T cell proliferation in response to allHIV antigens tests, and antibody production. While 13 of the16 primed patients receiving the HIV vaccine did develop Tcell responses, these were transient and were restricted to asubset of HIV antigens. Only one of these patients developed anantibody response to HIV.

The Bristol vaccine is the second AIDS vaccine to reach humantrials. The gp160 vaccine from MicroGeneSys of Meriden, Conn.,is also in Phase I trials and has been reported safe for humanuse.

Frank Volvovitz, president of MicroGeneSys, said that incurrent clinical HIVAC-1e studies, patients are given HIVAC-1efirst, followed by a booster of VaxSyn HIV-1, MicroGeneSys'gp160 protein vaccine. Initial studies of this combinationvaccine, reported at the 1990 International AIDS Conference,were encouraging, he added. This combination regimen is beingcompared with vaccinations using VaxSyn alone, with resultsdue in about a year, said Volvovitz.

-- Cynthia Robbins-Roth, Ph.D. BioVenture View

(c) 1997 American Health Consultants. All rights reserved.