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237 Safety of Live Recombinant ALVAC-HIV (vCP1521) Priming with AIDSVAX B/E Boosting in Thai HIV-1-Negative Participants: Preliminary Results
S. Nitayaphan*1, P. Pitisuttithum2, P. Singharaj1, W. Heyward5, S. Gurunathan4, J. Kim3, A. Brown1, and the Thai AIDS Vaccine Evaluation Group
1Armed Forces Res. Inst. of Med. Sci., Bangkok, Thailand; 2Mahidol Univ., Bangkok, Thailand; 3Walter Reed Army Inst. of Res., Rockville, MD, USA; 4Aventis Pasteur, Lyon, France; and 5VaxGen, Brisbane, CA, USA
Background: Several phase I and II trials of ALVAC-HIV candidate vaccines alone or boosted with soluble protein have been conducted, or are ongoing. vCP1521 is a recombinant canarypox vector vaccine that has been genetically engineered to express subtype E HIV-1 gp120 (92TH023) linked to transmembrane anchoring portion of gp41 (strain LAI), and HIV-1 gag and protease (LAI strain). However, there are no human data available for vCP1521. A prime-boost combination of candidate vaccines that elicit both humoral and cellular immune responses to viral strains prevalent within the region (subtypes E and B in Thailand), ALVAC-HIV vaccine prime and AIDSVAX B/E boost, is evaluated in this study.
Methods: The study is double-blind, randomized placebo-controlled phase II. Volunteers were enrolled and divided into 2 groups based on dose of booster vaccine.
Group I: Low-risk, HIV-seronegative Thai adults were given ALVAC-HIV (vCP1521, 106 CCID50) priming at weeks 0, 4, 12, and 24. At weeks 12 and 24, ALVAC was administered with 200 mg of a bivalent AIDSVAX B/E gp120 (100 mg for each B and E gp120 antigen). Other subjects received placebo injections. The ratio of vaccine:placebo recipients is 3:1.
Group II: Low-risk, HIV-seronegative Thai adults were given ALVAC-HIV (vCP1521, 106 CCID50) at weeks 0, 4, 12, and 24. At weeks 12 and 24, ALVAC was administered with 600 mg of a bivalent AIDSVAX B/E gp120 (300 mg for each B and E gp120 antigen). Other subjects received placebo injections. The ratio of vaccine:placebo recipients is 3:1.
Results: Reactogenicity data are still blinded. 57% and 67% of volunteers in Groups I and II, respectively, were male with median group ages of 20(24 years. The summary reactogenicity results are shown in the table below (which include both vaccine and placebo recipients). ALVAC was given in the left deltoid whereas AIDSVAX was given in the right deltoid.
| Group | Oral Temp
> 38C | ALVAC or placebo | AIDSVAC or placebo |
| Pain | Erythema | Induration | Pain | Erythema | Induration |
Group I
(n = 61) |
7% | 18% | 5% | 8% |
2% | 5% | 2% |
Group II
(n = 61) |
10% | 21% | 21% | 13% |
7% | 5% | 5% |
There was no significant difference in local reactogenicity of ALVAC reported after successive immunization or after administration concurrently with addition different doses of AIDSVAX B/E. There was no severe systemic reactogenicity reported. The frequency of mild and moderate systemic reactogenicity is no different between the 2 groups and is comparable to that seen in previous studies of ALVAC, AIDSVAX, and adjuvants. Six participants had serious adverse events; none were related to the study drug.
Conclusions: Prime-boost vaccination with ALVAC-HIV and AIDSVAX B/E appears to be safe and well tolerated in Thai adults. If immunogenicity is shown in addition to this safety profile, this vaccine is an appropriate candidate for advancement to phase III evaluation.
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