The first AIDS vaccine to be approved for clinical trials by theFood and Drug Administration is safe for humans, according toa study published in Tuesday's issue of the Annals of InternalMedicine.

VaxSyn HIV-1 (VaxSyn), developed by MicroGeneSys Inc. ofMeriden, Conn., also triggered an immune response in all 36healthy individuals given the vaccine in the study, whichstarted in 1988. Still to be shown is whether VaxSyn can blockHIV-1 infection.

The study is the first complete demonstration that an AIDSvaccine both provoked an immune response and was not toxic,said Dr. Raphael Dolin of the University of Rochester, thestudy's lead author. The study was sponsored by the AIDSVaccine Clinical Trial Network and conducted at Rochester,Vanderbilt University, Baylor College of Medicine, theUniversity of Maryland, Johns Hopkins University and MarshallUniversity.

VaxSyn has a recombinant-derived AIDS envelope proteingp160. In the study, 24 volunteers received four VaxSyninjections and 12 received three VaxSyn injections. Another 36participants received either a placebo or a hepatitis B vaccine.Those given VaxSyn made antibodies that bind to HIV-1 andmounted a cellular response against the AIDS virus.

The study's results are very encouraging, said Frank Volvovitz,MicroGeneSys' chief executive officer. The study has beenexpanded to include higher doses.

Another ongoing clinical trial of VaxSyn HIV-1 as a vaccinestarted in 1987 with a goal of defining an optimum dose,Volvovitz told BioWorld. Early results show that VaxSynadministered in dosages that are two to 16 times larger thanthose used in the published study trigger a much earlier andstronger immune response in healthy volunteers.

Volvovitz said that MicroGeneSys is "way ahead of othercompanies" in developing a product as both a vaccine and anAIDS treatment. The company aims to soon start VaxSynvaccine efficacy studies, he said. Because of the trials'complexity, he declined to predict when the vaccine might getFDA approval.

Phase II trials of VaxSyn as an immunotherapeutic agent fortreating AIDS infections are under way. With continuing goodresults, MicroGeneSys might file for product approval in 1992,Volvovitz said.

Other potential AIDS vaccines in FDA-approved clinical trialsinclude Bristol-Myers Squibb Co.'s vaccinia virus containingHIV envelope proteins gp41 and gp120, Genentech Inc.'sgp120, Chiron Corp.'s gp120, Immuno-U.S. Inc.'s gp160, andMicroGeneSys' p24 HIV core antigen. HPG-30, a viral coreantigen p17-based peptide vaccine, is being tested in Californiaand England by Viral Technologies Inc.

-- Carol Talkington Verser, Ph.D. Special to BioWorld

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