Immunogenicity and Safety of 2 Schedules of ALVAC-HIV vCP1452 in Chronically HIV-Infected Patients

Overview

Prior pilot studies have shown that four monthly injections of ALVAC-HIV (vCP1433) are immunogenic in 60% HIV-infected patients with a boosting effect obtained after 1 or 2 injections followed by a plateau or a decrease of these responses prior to interrupting therapy. The goal of the present study is to look for an improved vaccination schedule in terms of strength and duration of the HIV-specific immunity induced by the HIV-recombinant canary pox vector ALVAC-HIV (vCP1452) by testing a strategy of immunization involving a first series of two versus three monthly injections followed by a boost three months later.

Manon 02 is a phase II, multicentre, randomized, placebo-controlled study with 3 arms comprising 2 steps: Step I : Immunization phase from W0 to W24, on HAART The immunization will be administered by intramuscular injection : Arm A: one injection of vCP1452 at W0, W4, W8 and W20 + HAART, for a total of 4 injections Arm B: one injection of vCP1452 at W4, W8 and W20 + HAART, for a total of 3 injections Arm C: one injection of placebo at W0, W4, W8 and W20 + HAART, for a total of 4 injections or at W4, W8 and W20 + HAART, for a total of 3 injections Step II: Post immunization phase from W24 to W48, off HAART Discontinuation of antiretroviral therapy (ARV) from W24 to W48 : The ARV treatment interruption will be proposed at W24, 4 weeks after the last immunization, to patient who had completed their immunization phase and have CD4 cell counts \> 350 cells/mm3 and HIV plasma RNA \< 400 cp/ml. In order to be able to evaluate the capacity of the immune response to reduce the viral replication, a period of 16 weeks of interruption is recommended from W24 to W40. Resumption of antiretroviral therapy : From W24 to W40 : During this 16 weeks period, in case of a decline of CD4 cell counts below 250 cells/mm3 or of a loss of CD4 greater than 50% of the baseline value, HAART will be restarted. From W40 to W48 : HAART should be reintroduced if HIV-1 RNA levels \> 50 000 cp/ml on 2 consecutive measurements at two weeks interval even if the CD4 counts are above 250 cells/mm3.