Randomized Trial of a Switch to a Kaletra + Current Dual Nucleoside Reverse Transcriptase Inhibitor (NRTI) Backbone Versus Continuation of the Current Regimen in Patients With Poor Immune Responses to Highly Active Antiretroviral Therapy (HAART) in Patients With Complete Viral Suppression: A Pilot Study

To our knowledge our study is the first study showing persistent apoptosis in a subgroup of patients with complete viral suppression in association with poor immune recovery. Immune alterations independent of active viral replication may be responsible. Recent data suggests that immune responses to antiretroviral therapy depend on residual or restored thymic function. Improved CD4+ counts in patients despite virologic treatment failure are associated with greater thymic function, while poor T cell responses despite suppression of HIV are seen with decreased thymic function. Discordant immune responses may also be due to differential effects of particular antiretroviral agents on T cell apoptosis independent of viral suppression. For example, protease inhibitors have been shown to decrease rates of apoptosis of uninfected T cells. Viral replication is never completely suppressed with HAART, even when patients have undetectable plasma HIV RNA. Therefore, varying degrees of low level viral replication or replication in certain cellular compartments may continue to drive T cell apoptosis. Finally, our data suggests that ex vivo rates of Peripheral blood mononuclear cell (PBMC) apoptosis could potentially be used predict immune recovery or identify subgroups of patients who may benefit most from changes in HAART or adjunctive immunomodulatory therapies.

At this time, although there are excellent guidelines for how to evaluate and change therapy for patients with virologic failure, there are no recommendation and little data on approaches or strategies to change therapy for patients with poor immune responses. Kaletra (lopinavir/ritonavir) may be of benefit to patients with poor immune responses to HAART despite viral suppression. Kaletra may have greater potency and better suppression of viral replication that is below the level of detection by plasma polymerase chain reaction (PCR) for HIV-1 RNA. Kaletra also has an excellent pharmacokinetic profile which may result in superior inhibition of T cell apoptosis in vivo.