Third International Congress Drug Therapy in HIV Infection 3-7 November 1996 Glasgow, UK

THERAPEUTIC VACCINATION: A RANDOMIZED CONTROLLED STUDY OF THE EFFECT OF rgp160 ON PROGRESSION OF IMMUNE DEFICIENCY AND VIRAL BURDEN

Tsoukas, Chris M; Raboud, J; Bernard, N; Djurdjev, O; Cassol, S; Chernoff, D; Fong, I; Freedman, J; Gill, J; Goldberg, E; Lafreniere, R; Lee, S; Montaner, J; Poon, M-C; Rachlis, A; Schlech, W; Smith, G; Szabo, J; Todd, J; Thomas, R; Volvovítz, F
The Canadian HIV Trials Network, Canada; MicroGenesys Inc., Meriden, USA; Chiron Corp., Emeryville, USA; The Montreal General Hospital, Montreal, Quebec, Canada

Int Cong Drug Therapy HIV 1996 Nov 3-7;3:Abstract No. OP6.2
AIDS 1996, Vol. 10 (Suppl. 2);S14

It has been proposed that therapeutic vaccination of asymptomatic HIV infected individuals would improve anti-HIV immune responses thereby reducing viral burden and ultimately prolonging good health.

To determine if recombinant HIV envelope precursor protein rgpl60 (VaxSyn) would affect the course of HIV disease, 278 patients with CD4 counts > 500 cells/mm³ were enrolled in a double blinded, randomised, controlled, multicentre, three year study. Individuals received 320µg of rgp160 or placebo intramuscularly on days 0, 30, 60, 90, 180 and every 120 days thereafter. At two years, those on placebo were treated with rgp160 at the same dose and injection schedule as those on the initial active treatment arm. Cellular, humoral immune responses, and HIV viral assessments were carried out, including p24 serum antigenemia, HIV quantitative PBMC cocultivation, PCR analysis using a competitive template method and plasma HIV-1 RNA quantitation using the second generation 2.0 bDNA assay.

At enrollment, the median CD4 count was 662 cells/mm³ (range 474-1638). Augmented humoral immune responses and increased lymphocyte proliferative responses to rgp160 were noted in the treatment group, but not in the placebo controls. At enrollment, the median HIV RNA was 3.35 log₁₀ for the VaxSyn treated group and 3.25 log₁₀ for the placebo. At 2 years, the end of the controlled phase, the median values were 3.74 log₁₀ (VaxSyn) or 3.62 log₁₀ (placebo), not significantly different. Similarly analysis of the other viral measurements between groups revealed no statistically significant differences for p24 antigen, HIV quantitative cultures and PCR analysis using the competitive template assay.

In conclusion, although new or enhanced humoral and cellular immune responses were noted in rgp160 recipients in this controlled therapeutic vaccine study, no effect on viral burden was observed as determined by quantitative culture, antigenemia or plasma viremia.

Presenting author: Tsoukas, Chris M

1996-11-03
OP6.2

Originally published in AIDS Volume 10, Supplement 2 and hosted with permission of the publisher Lippincott Williams & Wilkins, 250 Waterloo Road, London, SE1 8RD, UK. Tel: +44 (0)20 7981 0700 Fax: +44 (0) 7981 0701

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