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Promising New Options for Treatment-Experienced Patients
Even triple-class–experienced patients can achieve virologic suppression with some of the new agents now available.
In October 2005, the U.S. Department of Health and Human Services updated its guidelines to state that even in deep salvage therapy, the goal of treatment should be complete virologic suppression. Nearly a year later, the International AIDS Society–USA followed suit, signaling a dramatic shift in the treatment paradigm for patients with limited options. This change was sparked by the successful introduction of several new agents — darunavir, maraviroc, etravirine, and MK-0518 — that enable even triple-class–experienced patients to achieve virologic suppression.
Based on convincing data from the POWER studies, the PI darunavir was approved by the FDA in late June for use in treatment-experienced patients (ACC Jun 28 2006). Like tipranavir, darunavir requires ritonavir boosting and, for the most part, remains active in patients who have had treatment failure on lopinavir-based regimens. Response to this agent is enhanced when it is combined with T-20.
Three additional antiretrovirals (from three separate drug classes) are also being reviewed by the FDA. The first is maraviroc, an oral CCR5 inhibitor that has been shown to be effective and safe in patients with CCR5-tropic virus (ACC Mar 1 2006) — and that is also safe in patients with mixed CXCR4- and CCR5-tropic viruses (see ACC’s IAS meeting report).
The second drug under review is the NNRTI etravirine, which remains active against viruses carrying the K103N mutation. The Achilles’ heel of this particular drug is its reduced efficacy against viruses with mutations in the 181 position, especially if combined with other NNRTI-specific mutations (Abstract 154 from the 13th Retrovirus Conference, Denver, 2006).
Last, but certainly not least, is the integrase inhibitor MK-0518, which has probably generated the most interest of all the new treatment options. In a study of treatment-naive patients, rates of virologic response were similar for regimens containing various doses of MK-0518 and for those containing efavirenz. Viral load, however, declined much more rapidly with MK-0518 (see ACC’s IAS meeting report). In another study of triple-class–experienced patients with very limited treatment options, MK-0518 resulted in at least transient virologic suppression (to <50 copies/mL) in the majority of patients treated (see ACC’s ICAAC meeting report).
Expanded-access programs have already been initiated or planned for each of these new drugs and will provide additional safety and efficacy data. Further experience will show when and how best to use these exciting new options with currently established drug combinations.
— Helmut Albrecht, MD
Published in AIDS Clinical Care December 29, 2006