IAS 2005: Rio de Janeiro; July 24-27

Key Links:

By Topic:


See Also
A dual-NRTI backbone for multiple patients >

UNBP3028 1/17

The Body PRO Covers: The 3rd International AIDS Society Conference on HIV Pathogenesis and Treatment

Full Virologic Suppression Can Be Maintained With Lopinavir/Ritonavir Alone; Single-Agent Therapies Worth Further Investigation

July 27, 2005

Last summer, at the XV International AIDS Conference, we were presented with the results of the courageous lopinavir/ritonavir (LPV/r, Kaletra)-monotherapy study.1 In that study, led by Joseph Gathe, a group of 42 HIV-infected patients with long-term virologic suppression were randomized to continue on their current regimen or to simplify it to lopinavir/ritonavir monotherapy. Over 48 weeks, virologic suppression was maintained in 95% of the control group as compared to 81% of those on monotherapy. In this latter group, 4 patients had detectable viremia; this included 1 person lost to follow-up and 3 true virologic breakthroughs.

There was some concern that it was only a matter of time before the other patients receiving monotherapy experienced the same fate: They may still have "undetectable" plasma viral loads, skeptics said, but those viral loads must be rising under the measurable threshold, and would surely break through soon.

To assess this possibility, J.E. McKinnon, from the University of Pittsburgh, and colleagues in Madrid, Spain, used an experimental Roche Amplicor PCR assay with a limit of quantitation of 3 copies/mL, and applied it to samples collected at weeks 4, 8, 12, 24 and 48 in both of the lopinavir/ritonavir-monotherapy study groups.

In patients with undetectable viral loads, the researchers were able to demonstrate a stable, low-level viremia of 3 to 5 copies/mL in more than 70% of the samples, with no trend towards an increase in any of the samples in either group. In the 3 patients who did have a virologic breakthrough in the lopinavir/ritonavir-monotherapy study, each breakthrough was preceded by a slow, steady increase in viral load beginning at week 8 and eventually exceeding 50 copies/mL by week 32.

This study clearly demonstrates that full virologic suppression can be maintained with a single agent in selected patients who have previously experienced long-term suppression while on HAART. This means that it is ethical, and even important, to pursue clinical trials on this approach. Doing so may allow us to better define the type of patient for whom single-agent therapy might be most appropriate, as well as which specific agents can be used. (For instance, trials of atazanavir [ATV, Reyataz] + ritonavir [RTV, Norvir] are ongoing.) Until the results of these studies are available, however, the single-agent approach will remain an experimental one -- and one that should not (at least, not yet) be offered to our patients as a standard of care. Perhaps next year.


  1. Gathe JC Jr, Washington MY, Mayberry C, Piot D, Nemecek J. IMANI-1 TC3WP single drug HAART -- proof of concept study. Pilot study of the safety and efficacy of Kaletra (LPV/r) as single drug HAART in HIV + ARV-naive patients-interim analysis of subjects completing final 48 week data. In: Program and abstracts of the XV International AIDS Conference; July 11-16, 2004; Bangkok, Thailand. Abstract MoOrB1057.

Abstract: The level of persistent viremia does not increase after simplification of maintenance antiretroviral therapy to lopinavir/ritonavir alone (Oral WeOa0203)
Authored by: JE McKinnon, JR Arribas, F Pulido, R Delgado, JW Mellors

Affiliations: University of Pittsburgh, Pittsburgh, United States of America; Hospital La Paz, Madrid, Spain; Hospital Doce de Octubre, Madrid, Spain

It is a part of the publication The 3rd International AIDS Society Conference on HIV Pathogenesis and Treatment.

Please note: Knowledge about HIV changes rapidly. Note the date of this summary's publication, and before treating patients or employing any therapies described in these materials, verify all information independently. If you are a patient, please consult a doctor or other medical professional before acting on any of the information presented in this summary. For a complete listing of our most recent conference coverage, click here.

The content on this page is free of advertiser influence and was produced by our editorial team. See our content and advertising policies.