BIOCINE’s RECOMBINANT gp120 AIDS VACCINE PLUS ADJUVANT PRODUCED NEUTRALIZING ANTIBODIES
BIOCINE's RECOMBINANT gp120 AIDS VACCINE PLUS ADJUVANT PRODUCED NEUTRALIZING ANTIBODIES against HIV in 12 subjects who received three immunizations with the vaccine formulation, James Kahn, San Francisco General Hospital, reported July 20 at the VIII International AIDS Conference in Amsterdam. In addition, eight of the 12 vaccinated subjects developed "cross-neutralizing antibodies directed against MN, a related HIV isolate." Biocine is the 50/50 joint venture of Chiron and Ciba-Geigy. Kahn's study involves a total of 42 seronegative adults divided into six groups. Thirty-two subjects received recombinant gp120 antigen in combination with Biocine's MF59 adjuvant emulsion, alone or with increasing doses of an immunomodulator, muramyl tripeptide (MTP-PE). Ten subjects received MF59 without gp120 antigen that was formulated both with and without MTP-PE. All participants received vaccinations at zero, one month and six months and are to be administered a fourth dose at one year. Kahn reported preliminary results in 16 subjects from the first two groups. Twelve received gp120/MF59, six with MTP-PE and six without. Four subjects received only MF59, two with MTP-PE and two without. While subjects receiving gp120/MF59 alone had no serious systemic side effects, those who received the vaccine with MTP-PE had significant side effects, such as fever, muscle aches or headaches. The National Institute of Allergy and Infectious Diseases, which is funding the trial through its AIDS Vaccine Clinical Trials Network, commented that "significantly, 18 volunteers who received only MF59 and vaccine appear to have similar antibody responses but only mild side effects compared with those who received the complete adjuvant plus vaccine." NIAID said that results of the trial are still being analyzed "to determine which dose of MTP-PE, if any, is required for the most effective production of neutralizing antibodies." Clinical data on Genentech's gp120 vaccine were also presented at the conference. Mary Lou Clements, John Hopkins Center for Immunization Research, reported that 28 uninfected adult volunteers were randomized to receive either 100 mcg gp120, 300 mcg gp120, or the adjuvant alum at zero, four and 32 weeks. Clements said that two weeks after the third immunization, seven of 10 subjects who received the 300 mcg dose "developed fusion inhibition antibody, and neutralization antibody was detected in nine of 10 vaccines to the homologous isolate IIIB." She added that in the group that showed neutralizing antibody, three individuals actually had titers of greater than 1:90." Robert Belshe, St. Louis University School of Medicine, reported in a poster session on another AIDS vaccine that Immuno AG's recombinant gp160 stimulated HIV antibodies and was well tolerated in 60 HIV-negative volunteers. Subjects received four injections of either 12.5 or 50 mcg of vaccine or alum in a carrier, deoxycholate. Patients later received boosters at one, six and 12 months. Belshe said the vaccine was started at a low dose and the antibody response elicited was not strong enough to neutralize HIV. The trial is being extended to test a 200 mcg dose in 25 volunteers, which Belshe hopes will produce functional antibody that will attack and kill HIV. The vaccine was developed under a research agreement between Vienna, Austria-based Immuno AG, NIAID and the National Cancer Institute. NIAID said it was the first candidate AIDS vaccine made from a recombinant HIV protein produced in mammalian cells, resulting in a vaccine "that more closely mimics the gp160 protein of HIV." In a July 21 presentation, Immune Response Corp. and Rhone- Poulenc Rorer reported that their HIV immunotherapeutic vaccine stimulated HIV antibody and cellular immune responses in a dose- ranging study of 48 asymptomatic patients. Subjects received either one of four doses of the vaccine (50 mcg, 100 mcg, 200 mcg and 400 mcg) or a control. The 100 mcg dose was the lowest to stimulate a statistically significant immune response, the companies said. "Antibody responses were measured by two methods, one which qualitatively indicates broad-based immune responses to several HIV proteins, and a second method which quantitatively measures responses against p24," the two companies explained. The qualitative method indicated that the HIV immunotherapeutic stimulated broad-based antibody responses against HIV proteins in several treated patients. The quantitative method demonstrated up to 64-fold increases in antibody responses directed against the p24 core HIV protein." Patients with low baseline antibody titers at study entry responded more strongly to treatment than those with higher baseline antibody titers, the companies said. A separate Phase II/III clinical trial in a different patient group is currently under way and is expected to be completed late this year. That trial is looking at a number of markers, particularly viral burden.
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