Interruption of HAART Started during Acute or Recent HIV Infection: Final Results of ACTG 371

The results of earlier studies have suggested that therapy during early HIV infection followed by treatment interruption may enhance viral control and allow deferral of permanent therapy.

As reported at the 15th Conference on Retroviruses and Opportunistic Infections (CROI 2008) last week in Boston, researchers with the AIDS Clinical Trials Group study ACTG 371 hypothesized that individuals treated during acute HIV infection (estimated infection in the prior 14 days) would have better viral control than those treated during recent HIV infection (estimated infection in the prior 15-180 days) when assessed 24 weeks after treatment interruption.

Study participants entered a Phase II multicenter, prospective, non-randomized trial of ritonavir-boosted protease inhibitor-based antiretroviral therapy stratified by acute versus recent infection.

If participants sustained at least 52 weeks of viral suppression below 50 copies/mL, treatment was interrupted. If viral load rebound occurred (> 5000 copies/mL on 3 consecutive visits or > 50,000 copies/mL on 2 visits), a second course of antiretroviral treatment was started. If this successfully in suppressed viral load, it was again followed by another treatment interruption.

Between July 1999 and September 2003, 121 subjects were enrolled at 15 AIDS Clinical Trials Group (ACTG) sites; 115 were men, the median age was 34 years, 84 were white, and 114 had no history of injection drug use. The median CD4 cell count at baseline was 535 cells/mm³; the median baseline viral load was higher in the acute infection group compared with the recent infection group (210,000 vs 43,000 copies/mL, respectively); approximately 15% in each group had baseline drug resistance mutations.

The primary study endpoint was maintaining a plasma viral load below 5000 copies/mL for 24 weeks following the first or second treatment interruption. The 73 subjects (28 with acute infection, 45 with recent infection) who started the first treatment interruption made up the primary endpoint analysis population.

Results

• The primary endpoint of sustained virological suppression below 5000 copies/mL was achieved in 29 of the 73 participants (40%) undergoing a first treatment interruption.

• There was no significant difference in virological response between patients with acute infection and those with recent infection (43% vs 38%; P = 0.81)

• Successful outcomes were more common in the combined trial population with baseline viral load below 100,000/mL than in those with greater than 100,000/mL (48% vs 26%, respectively).

• Treatment was in general well tolerated.

Conclusion

Based on these findings, the study authors concluded, "Of subjects treated during acute or recent infection, 40% sustained a viral load < 5000 copies/mL after 24 weeks of treatment interruption. There was no significant difference between the 2 groups."

They added that, "Even earlier intervention may be required to improve outcome of primary HIV infection."

Univ of California, San Francisco, CA; Univ of Colorado, Denver, CO; Harvard Univ, Boston, MA; NIAID, NIH, Bethesda, MD; New York Univ, New York, NY; Univ of California, San Diego, CA; and Univ of Rochester, NY, CA.

View PDF of poster.

2/15/08

Reference
P Volberding, E Connick, R Bosch, and others (the AIDS Clinical Trials Group 371). Interrupted ART of Acute Compared with Recent HIV Infection: Final Results of ACTG 371. 15th Conference on Retroviruses and Opportunistic Infections. Boston, MA. February 3-6, 2008. Abstract 693.

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