After 24 weeks of treatment in triple-class-experienced HIV-infected patients, the investigational protease inhibitor (PI) TMC114 controlled resistant HIV significantly better than comparison regimens. Richard Haubrich, MD, from the University of California, San Diego, reported an average viral load drop of 1.85 log copies/ml with the highest dose of TMC114 vs 0.27 log with alternative PI regimens.
The findings presented by Dr. Haubrich at the 12th Conference on Retroviruses and Opportunistic Infections in Boston, Massachusetts, raised expectations that ritonavir-boosted TMC114 may be a potent option for people with multiclass resistance. At the highest dose of TMC114/ritonavir, viral loads dropped below 50 copies/mL, even in five of 13 people for whom resistance testing could identify no other active antiretrovirals.
Researchers from 14 countries tested TMC114/ritonavir at 4 doses—400/100 mg and 800/100 mg once daily, and 400/100 mg and 600/100 mg twice daily—in 397 people with triple-class experience, one or more primary PI mutations, an average viral load of 4.61 log10 copies/ml, and an average CD4+ cell count of 136 cells/mm3. Baseline numbers were equivalent in a control group of 100 people randomised to start one or two alternative boosted PIs selected by their clinicians.
Viral load declines at Week 24 averaged 1.85 logs with the highest dose of TMC114 vs 0.27 logs in the control arm in a noncompleter-equals-failure analysis (P 3, compared with 15 cells/mm3 in the control group.
Among people taking the highest dose of TMC114, 47% had a viral load under 50 copies/ml at Week 24 and 72% had at least a tenfold drop in viral load. Of 40 people in the highest-dose group who had three or more primary protease mutations when they started the new PI, 19 had a viral load under 50 copies/ml 24 weeks later.
Four of 397 people had to stop TMC114 because of side effects. Overall toxicity rates did not differ significantly between the combined TMC114 groups and the control group.
Phase 3 studies using the 600/100-mg twice-daily dose of TMC114/ritonavir are slated to start later this year.
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Katlama C et al. Efficacy of TMC114/r in 3-class experienced patients with limited treating options: 24-week planned interim analysis of 2 96-week multinational dose-finding trials. Twelfth Conference on Retroviruses and Opportunistic Infections, Boston, abstract 164LB, 2005.