Clinical trial results on recombinant HIV vaccines produced byGenentech Inc. (NYSE:GNE) of South San Francisco, Calif.;Biocine, a joint venture between Chiron Corp. (NASDAQ:CHIR)and Ciba-Geigy; and Immuno AG of Vienna, Austria; are beingpresented today at the Ninth International Conference on AIDSin Berlin.
These trials are being conducted by the AIDS vaccine clinicaltrials network (AVCTN), which is supported by the NationalInstitute of Allergy and Infectious Diseases (NIAID).
One of those trials, being conducted at St. Louis University, ison Genentech's recombinant gp120 MN candidate HIV vaccine.This consists of a viral envelope protein subunit engineeredfrom the MN strain, one of the most prevalent strainscirculating in the U.S., in conjunction with an alum adjuvant.
Principal investigator Robert Belshe described the currentresults of a double-blind randomized Phase I trial of theGenentech vaccine in non-infected people at low risk for HIVinfection.
According to Belshe, three injections of the vaccine (either300 micrograms or 600 micrograms) given within six monthscan safely stimulate neutralizing antibodies to the MN strain,as well as two other common strains of HIV (SF-2 and IIIB).
Also, Biocine's recombinant gp120 SF-2 candidate vaccine iswell-tolerated and stimulates high levels of neutralizingantibodies to both the SF-2 strain and the MN strain, accordingto the results of ongoing trials at another AIDS vaccineevaluation group (AVEG) site at Vanderbilt University inTennessee.
Biocine's vaccine candidate, like Genentech's, employs arecombinant gp120 viral subunit. Unlike Genentech's, it iscombined with one of two novel adjuvants: MTP-PE/MF59 orMF59 alone.
The participants in this trial, which included both men andwomen, were given a primer vaccination (of either 15micrograms or 50 micrograms) and two boosters at one and sixmonths. Investigator Barney Graham and his colleagues foundthat although both dosages stimulated neutralizing antibodies,the higher one evoked a significantly better response. As well,two-thirds of the people who responded also developedneutralizing antibodies against the MN strain of HIV, and somehad antibodies against HIV IIIB.
The clinical trial on Immuno AG's recombinant gp160 HIVvaccine (based on the IIIB strain of the virus) is the first ofthe AVEG trials to test the idea of using HIV vaccinestherapeutically. In trials on HIV-infected but asymptomaticvolunteers, the vaccine proved safe and well-tolerated.
According to principal investigator David Schwartz of JohnsHopkins University, none of the participants had evidence ofcellular immunity to HIV envelope proteins when they enrolledin the study.
Repeated injections of the putative vaccine, however, inducedor restored at least one aspect of cellular immunity, T-cellrecognition of the HIV envelope proteins. Data on whether thevaccine can also induce cytotoxic T lymphocytes or stimulatenew antibody responses still need to be analyzed.
-- Jennifer Van Brunt Senior Editor
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