This phase 2 study will evaluate the safety, immunogenicity and optimal timing of two injections at three dose levels of the tgAAC09 vaccine in healthy volunteers. Study volunteers will receive two intramuscular injections of tgAAC09 or placebo at Months 0 and 6 (groups A, C, E and G) or at Months 0 and 12 (groups B, D and F) and be followed for a total of 18 months following the first injection with the exception of group G in which volunteers will be followed for 12 months after the first injection (6 months after the second injection). This study will explore whether boosting is possible, and compare a shorter and more practical six-month time interval with a twelve-month time interval.
The study design will also assess the effect of the presence of anti-AAV2 capsid neutralizing antibodies at the time of vaccination on the safety and immunogenicity of tgAAC09. Since the prevalence of pre-existing neutralizing antibodies to AAV2 capsid is high (IAVI and Targeted Genetics, data on file), this protocol amendment adds Group G which is composed of volunteers who have documented pre-existing anti-AAV2 capsid neutralizing antibodies titers ≤ 1/8. This will assure that there are sufficient numbers of volunteers with and without antibodies for a useful comparison.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
91
Sterile isotonic buffered salt solution
Desmond Tutu HIV Centre Cape Town
Cape Town, South Africa, South Africa
Medunsa
South Africa, South Africa, South Africa
Perinatal HIV Research Unit, Baragwanath Hospital
Soweto, South Africa, South Africa
Uganda Virus Research Institute
Entebbe, Entebbe, Uganda
Zambia-Emory HIV Research Project (ZEHRP)
Lusaka, Lusaka Province, Zambia
Safety: proportion of volunteers with severe local and systemic reactions, proportion of volunteers with other SAEs (including laboratory abnormalities) related to study vaccine, number of volunteers with SAEs related to study vaccine
Time frame: 18 months
Proportion of volunteers with HIV-1 specific T- cell responses quantified by γ-IFN ELISPOT and magnitude of the response, and proportion of volunteers with HIV-1 specific binding antibodies and magnitude of the response
Time frame: 18 months
Safety: high versus low or negative titres of neutralizing antibodies to AAV2 at the time of each vaccination
Time frame: 18 months
Immunogenicity: proportion of volunteers with HIV-1 specific T- cell responses by γ-IFN CFC or other T-cell assays
Time frame: 18 months
Immunogenicity endpoints in volunteers with high versus low or negative titres of neutralizing antibodies to AAV2 at the time of each vaccination
Time frame: 18 months
Immunogenicity endpoints in volunteers with versus without four-fold or greater increase in titres of neutralizing antibodies to AAV2 after vaccination
Time frame: 18 months
Immunogenicity endpoints after the second study injection, compared with the first study injection
Time frame: 18 months
Immunogenicity endpoints after the second study injection following a twelve-month interval compared to a six-month interval
Time frame: 18 months
Vaccine biodistribution: presence and persistence of vaccine in peripheral blood mononuclear cells (PBMC), saliva, nasal swabs, urine and semen or cervical/vaginal secretions
Time frame: 18 months
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