By Rachel Parratt
SYDNEY, AUSTRALIA -- July 25, 2007 -- Phase 2 results for the CCR5 antagonist vicriviroc (ACTG 5211) show potent and sustained viral suppression through 48 weeks in treatment-experienced HIV patients, according to research presented here at the 4th International AIDS Society (IAS) Conference on HIV Pathogenesis, Treatment and Prevention.
These findings represent the longest follow-up period so far for any CCR5 antagonist, said principal investigator Roy Gulick, MD, Director, Cornell HIV Clinical Trials Unit, Associate Professor of Medicine, Weill Medical College, Cornell University, and Associate Attending Physician, New York Presbyterian Hospital, New York City, New York.
For the multicenter study, Dr. Gulick and researchers with the National Institutes of Health-sponsored AIDS Clinical Trial Group (ACTG) enrolled 118 patients who did not respond to a ritonavir-containing regimen (HIV RNA levels >= 5000 copies/mL).
These patients were randomized to receive either vicriviroc (5 mg, 10 mg, 15 mg daily) or placebo, and all received an optimized ritonavir-boosted protease-inhibitor-containing antiretroviral regimen.
At 48 weeks, patients in the 10-mg and 15-mg vicriviroc groups achieved median viral load decreases of 1.92 and 1.44 (log10 copies/mL), and median increases in CD4 cell counts of 130 and 96 cell/mcL from baseline, respectively.
Virologic suppression (HIV RNA <50 copies/mL) at 24 weeks in 20 patients from the 10-mg and 15-mg vicriviroc groups was sustained for 70% of these patients through to 48 weeks.
Fewer patients experienced virologic failure in the vicriviroc groups than the placebo group (27%, vicriviroc 10 mg; 33%, vicriviroc 15 mg; 86%, placebo) and fewer patients discontinued the study treatment early (37%, 30%, 82%, respectively).
There were no significant differences in grade 3 or 4 adverse events between vicriviroc and placebo. Eight malignancies were reported, six in the vicriviroc group and two in the placebo group.
These 48-week data are the "first to demonstrate potent virologic suppression with a CCR5-based regimen sustained through 48 weeks," Dr. Gulick commented in his oral presentation on July 24th.
Funding for this study was provided by Merck.
[Presentation title: ACTG 5211: Phase II Study of the Safety and Efficacy of Vicriviroc (VCV) in HIV-Infected Treatment-Experienced Subjects: 48 Week Results. Abstract TUAB102]
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