FDA Advisory Committee Recommends Approval For Pfizer’s Selzentry

The FDA Antiviral Drugs Advisory Committee has recommended the approval of Pfizer’s Selzentry (maraviroc) tablets for use in treatment-naive adult patients with CCR5-tropic HIV-1 virus, as part of combination therapy.

Reportedly, Selzentry was granted accelerated approval in August 2007 and full approval in November 2008 by the FDA for use in treatment-experienced adult patients with only CCR5-tropic HIV-1 virus, in combination with other antiretroviral therapies.

The company stated that the Advisory Committee reviewed 48-and 96-week efficacy and safety data from the ongoing phase 3 MERIT (Maraviroc versus Efavirenz Regimens as Initial Therapy) trial and MERIT ES (analysis of the MERIT study with the enhanced sensitivity Trofile assay).

Results of 48-weeks of MERIT showed that Selzentry plus Combivir (zidovudine/lamivudine) was as effective as Sustiva (efavirenz) plus zidovudine/lamivudine at reducing viral load for the co-primary endpoint of <400 copies/ml, but did not show non-inferiority for the co-primary endpoint of <50 copies/ml at 48-weeks.

However, safety results at 96-weeks showed that among those patients who remained on therapy, less than half the number of malignancies were observed in patients taking Selzentry, compared to those taking efavirenz. Additionally, no new safety signals were identified in association with Selzentry at 96-weeks.

MERIT ES is a retrospective analysis, which utilised the sensitivity Trofile assay in screening samples from the MERIT trial. Results of MERIT ES at 48-weeks showed that treatment-naive patients with CCR5-tropic HIV-1 taking Selzentry plus zidovudine/lamivudine, experienced comparable virologic suppression to undetectable levels to those taking efavirenz plus zidovudine/lamivudine.

Through the joint venture with GlaxoSmithKline, which is expected to close in the fourth quarter of 2009, Pfizer remains committed to the expansion of Selzentry/Celsentri’s current indications to include appropriate treatment-naive populations throughout the world.

Selzentry is an oral medicine that blocks viral entry to human cells. Rather than fighting HIV inside white blood cells, Selzentry prevents the virus from entering uninfected cells by blocking its predominant entry route, the CCR5 co-receptor.