Effect of therapeutic immunization with HIV type 1 recombinant glycoprotein 160 immunoAG vaccine in HIV-infected individuals with CD4⁺ T cell counts of ≥500 and 200-400/mm³ (AIDS Clinical Trials Group Study 246/946)

AIDS Clinical Trials Group (ACTG) 246/946 was a double-blinded, randomized, controlled trial of HIV-1 MN rgp160 ImmunoAG vaccine in HIV-infected patients with CD4⁺ T cell counts ≥500 and 200-400/mm³. The main objectives were to study the safety and immunogenicity of this vaccine and to study the persistence of the immune responses after vaccination over a longer period of time. Fifteen patients with CD4⁺ T cell counts of ≥500/mm³ were enrolled in the ACTG 246 study. ACTG 246 patients received a monthly injection of vaccine or control for 6 months and then injections every 2 months. After completion of this study, seven new patients with CD4⁺ T cell counts of 200-400/mm³ entered into the ACTG 946 study. These study patients received highly active antiretroviral therapy (HAART) (ritonavir, didanosine, and stavudine) for 9 weeks to stabilize their viral load and then each patient received a monthly injection of vaccine or control substance for 6 months with HAART. The study of these two relatively small populations showed that the vaccine was safe without any adverse effect both in the patients with CD4⁺ T cell counts of ≥500 and 200-400/mm³. The vaccine was also immunogenic in patients with CD4⁺ T cell counts of ≥500/mm³ as measured by gp160-specific lymphocyte proliferative responses, and it persisted after they had received more than six vaccine injections, for a longer period of time.