2248761 (IDX899, GSK2248761)

2248761 (formerly IDX899, GSK 2248761) is a non-nucleoside reverse transcriptase inhibitor in development by ViiV Healthcare, a specialist HIV company established by GlaxoSmithKline (GSK) and Pfizer. 

In vitro studies done when Idenix Pharmaceuticals was developing this drug under the name IDX899 showed a long half-life and ability to inhibit both wild-type and NNRTI-resistant HIV.

A  proof-of-concept study in treatment-naive patients took place that showed efficacy and tolerability. This seven-day study enrolled 30 treatment-naive patients with viral load ≥5000 copies/ml and CD4+ T-cell count ≥200 cells/mm3 who were randomised (8:2) to receive IDX899 or placebo once daily. IDX899 showed efficacy and was well-tolerated at three different dosing levels (200mg, 400mg and 800mg).1 2

At the 800mg level, the median changes in HIV-1 plasma RNA from baseline to day 8 were -1.95 log10 copies and median CD4+ T-cell count increased by 52 cells/mm3. Further evaluation of IDX899 in combination therapy to assess long-term safety and response durability are being planned.3

Phase II studies will be dose-ranging and will attempt to characterise the dose-response and concentration-response curves.1

References

  1. Zala C et al. IDX899, a novel HIV-1 NNRTI with high barrier to resistance, provides suppression of HIV viral load in treatment-naive HIV-1 infected subjects. 17th International AIDS Conference, Mexico City, abstract THAB0402, 2008
  2. Murphy R et al. In vitro cross-resistance profile, antiviral activity, safety and pharmacokinetics in hiv-1-infected patients of IDX899, a novel HIV-1 NNRTI with high barrier to resistance. 17th International HIV Drug Resistance Workshop, Sitges, abstract 5, 2008
  3. Murphy R et al. Antiviral activity, safety and pharmacokinetics of IDX899, a novel HIV-1 non-nucleoside reverse transcriptase inhibitor with high barrier to resistance, in treatment-naïve HIV-1-infected patients. 17th International HIV Drug Resistance Workshop, Sitges, abstract 25, 2008
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