IAS: Maraviroc produces best results when combined with another active drug

Adding another potent antiretroviral to the new CCR5 antagonist maraviroc (Celsentri) in treatment-experienced patients gives added benefit, according to a new analysis of the MOTIVATE study data presented as a poster to the recent International AIDS Society Conference in Sydney.

The MOTIVATE 1 and 2 studies were conducted in heavily treatment-experienced HIV-infected individuals with CCR5-tropic virus. Patients in the studies had taken several antiretroviral regimens and developed significant drug resistance. The trials were sufficiently similar in design to allow the results to be combined.

Patients were given maraviroc or placebo plus optimised background therapy (OBT) but for some patients that OBT contained at least one potent antiretroviral that the patient had never used before. These were enfuvirtide (Fuzeon), lopinavir/ritonavir (Kaletra), tipranavir (Aptivus), fosamprenavir (Telzir) or atazanavir (Reyataz).

Darunavir (Prezista) was not included in the trial as it was only available under expanded access at the time of the study and no information on drug interactions was available.

The investigators used the GSS (Genotypic Susceptibility Score) to indicate the total number of drugs in the OBT to which the patient's virus was susceptible.

Patients taking maraviroc plus another potent drug they had not used before were significantly more likely to achieve viral loads of less than 50 copies/ml.

For example, 53% of patients taking maraviroc 300mg twice a day plus enfuvirtide for the first time achieved viral loads of less than 50 copies/ml compared to just 33% of enfuvirtide resistant or experienced patients taking maraviroc.

The results are consistent with results from a GSS analysis which showed that patients with more potentially active drugs in their OBT were more likely to achieve virologic suppression on maraviroc. Fifty-five per cent of patients with two active drugs acheived viral load below 50 copies/ml at week 24, compared with 32% of patients with no active drugs in the OBT.

The authors say the data demonstrate the added treatment benefit of including another potent new drug as part of an OBR when initiating maraviroc in patients who are known to have significant resistance.

Maraviroc recently received accelerated approval for use by treatment experienced patients in the US. Formal approval in Europe is expected in the autumn.