Aventis Pasteur remains committed to the continued development of its ALVAC vector as a preventive AIDS vaccine. The knowledge gleaned from HIV Vaccine Trials Network (HVTN) 203 will be useful in moving future studies forward both in the U.S. and internationally.
There is no known correlate of protection for HIV vaccines. HVTN 501 was designed to determine possible correlates in addition to looking at efficacy of a prime-boost combination, using an ALVAC-HIV (vCP1452) prime and a gp120 boost. Because a ‘correlate of protection’ analysis would not be able to be obtained from HVTN 501, that trial will not proceed. The decision, made by the NIAID and HVTN, was based on a review of data from HVTN 203 and is supported by the company.
However, the opportunity to see if the prime-boost, using ALVAC-HIV and gp120, is efficacious remains imminent. A phase III trial to be undertaken in Thailand with the Thai government and Walter Reed Army Institute of Research is planned to begin later this year. The Thai trial and HVTN 501 had different objectives. The Thai study is a straightforward community-based trial with efficacy as its outcome. The company will cooperate fully with the trial.
The NIAID and HVTN remain fully committed to several other trials using ALVAC-HIV (vCP1452) and the company intends to support them. HVTN (HIVNET) 026 looks at the safety and immunogenicity of ALVAC-HIV (vCP1452) and gp120 MN in populations outside of the U.S. HVTN 039 is studying whether a higher dose level of ALVAC-HIV (vCP1452) results in an enhanced HIV-specific immune response in vaccinees. HVTN 042 will seek to determine if there is a benefit to using a different boost, in this case lipopeptides and is in collaboration with the Agence Nationale de Recherche Sur de Sida (ANRS).
Importantly, all of these trials will help guide the company’s R and D efforts in this area as well as build a continuing record of safety for these approaches. ALVAC-HIV has been studied in more than 2,000 people throughout the world and has an excellent safety profile.
In addition, ALVAC-HIV continues to be investigated as a therapeutic option for HIV. There are currently 10 phase I/II trials underway in North America and Europe studying therapeutic vaccination with ALVAC-HIV as an adjunct to HAART. Data have been obtained that demonstrate the safety/immunogenicity of ALVAC-HIV (vCP1452) in HAART-treated patients. The results, to date, warrant further assessment of the clinical benefits of such immunotherapeutic strategies in larger, controlled clinical studies.