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July 20, 2011

Short course antiretroviral therapy in primary HIV infection: the SPARTAC results

Short course antiretroviral therapy in primary HIV infection: the SPARTAC results

In one of the late-breaker presentations at the 2011 IAS Conference on HIV Pathogenesis, Treatment and Prevention, Elizabeth Hamlyn presented data from the SPARTAC (Short Pulse Anti Retroviral Therapy at HIV Seroconversion) trial, an international randomized controlled trial of primary HIV infection.

It is known that HIV reservoirs are established early in infection and that this sets the stage for immune activation and immunologic destruction which is never completely reversed. Early onset of antiretroviral therapy may confer a potential immunological benefit.

The primary objective of this study was to determine if short course ART delays the time to CD4 counts<350 and/or the initiation of long-term ART. 371 patients with primary HIV infection (PHI, laboratory evidence of infection within 6 months of a negative test) from 8 countries were randomized to either a 48-week short course ART (ART-48), a 12-week short course ART (ART-12) or no therapy (Standard of Care, SOC) with an average follow-up of 4 years.

Time to the primary endpoint was 157 weeks for SOC, 184 weeks for ART-12 and 222 weeks for ART-48. The average CD4 over 4.8 years for ART-48 was 138 cells/mm3 higher than for SOC. ART-48 was associated with a significant reduction in viral set point of HIV RNA of 0.44 (0.25,0.64) log10 copies/ml sustained to 60 weeks after stopping therapy.

The investigators examined secondary endpoints and found that there was no significant difference between the groups for AIDS, death or serious adverse events. In addition, no difference in CD4 decline was noted after ART interruption in treatment groups compared to decline in SOC (p=0.92). The investigators noted that the delay in time to CD4 <350 for people on the ART-48 arm may not have been any longer than the time spent on treatment.

A post hoc analysis however revealed that people who started treatment in the ART-48 arm who started ART less than 12 weeks after becoming infected had a greater reduction in the risk of disease progression (hazard ratio 0.48, 95% CI 0.30 – 0.78, p=0.003). These data point to a possible benefit of early treatment of PHI, both in terms of improved clinical outcomes and suggest a benefit of reduced HIV transmission due to the suppression of viral loads.

Reference: Fidler S. The effect of short-course antiretroviral therapy in primary HIV infection: final results from an international randomised controlled trial; SPARTAC [Oral Abstract]. Presented July 20, 2011, at the 6th IAS Conference on HIV Pathogenesis, Treatment and Prevention, Rome, Italy. Abstract WELBX06.

Source: Source: Reporting for PRN news from Rome, Italy: Anita Radix, MD