Structured treatment interruption studies reported at the Lisbon conference gave some hope that a small proportion of individuals can come off therapy and maintain control of HIV.
A group from Brussels reported on 7 patients who had maintained viral load below 50 copies for between 12 and 36 months after commencing triple therapy during primary infection. After stopping therapy, three out of seven patients experienced no viral rebound, and rebound in the other patients was associated with the continued presence of CD8+ activation markers, suggesting ongoing viral replication.
Dr Ruiz from Barcelona reported on 12 patients who had begun treatment after primary infection, and who had maintained viral load below 50 copies for more than 2 years. In this study, individuals stopped treatment until their viral load rose above 3,000 copies, or for a maximum of thirty days if it did not rebound to that level.
Twelve individuals agreed to stop therapy. Two out of 12 experienced no viral rebound during the first one month interruption, whilst the other 10 experienced some degree of rebound. In five cases, viral load did not become detectable until 10 to 15 days ofter stopping treatment, whilst five others experienced no detectable viral rebound until 18-21 days after stopping treatment.All individuals returned to viral load below 50 copies after resuming their previous HAART regimen.
This study will continue to expose patients to structured treatment interruptions to measure whether the viral load rebound becomes more delayed or less pronounced, and whether or not individuals develop p24-specific CD4 repsonses that are assumed to control HIV in long-term non-progressors. p24-specific CD4 repsonses were detectable in two individuals at fairly low levels after the first treatment interruption.
Finally, a team from a Pennsylvania clinical practice reported on what happened when patients interrupted treatment in real life, for whatever reasons. They reviewed patient records and identified 18 multiple interruptions, and discovered that after the first treatment interruption, viral load rebounded to more than 0.7 log below baseline (the level at which the patient started treatment) in later treatment interruptions in ten cases. In a further six cases, viral load did not return to baseline during later treatment interruptions, but the degree of rebound was more pronounced.
De Wit S et al. Discontinuation of therapy after treatment for primary HIV-1 infection. Seventh European Conference on Clinical Aspects and Treatment of HIV Infection, Lisbon, abstract 413, 1999.
Ruiz L et al. Structured treatment interruptions in chronically HIV-1 infected patients after long-term viral suppression. Seventh European Conference on Clinical Aspects and Treatment of HIV Infection, Lisbon, abstract 1224, 1999.
Woodward WC et al. Intermittent antiretroviral therapy can induce reduction of viral rebound during ART-interruption. Seventh European Conference on Clinical Aspects and Treatment of HIV Infection, Lisbon, abstract 236, 1999.