Yet more data have been gathered suggesting that the use of structured treatment interruptions by HIV-positive HAART-treated patients needs careful planning and monitoring.
Spanish research presented as a poster to the 43rd ICAAC in Chicago today found that patients who were taking an NNRTI-containing regimen were significantly more likely to experience virological rebound and develop resistance mutations than individuals who took a structured break from a regimen based on a protease inhibitor. Two studies have also been presented to this year's ICAAC, and are reported here and here on aidsmap, which suggest that CD4-guided treatment interruptions could be a viable option for some patients.
Investigators studied 187 patients who discontinued their HAART regimen and moved to a regimen of 400mg ddI plus 500mg hydroxuyrea twice-daily. All the patients had a CD4 cell count of at least 350 cells/mm3 and a viral load below 50 copies/mL when HAART was discontinued. The majority of patients, 116, were taking an NNRTI-containing regimen, with the remaining 69 taking a protease inhibitor.
In total, 21% of patients (19 who took a protease inhibitor and 20 an NNRTI) experienced a rebound in their viral load to above 10,000 copies/mL when they took a break from HAART and moved to the ddI/hydroxuyrea maintenance therapy. All the patients who resumed HAART taking a protease inhibitor saw their viral load fall back to below 50 copies/mL. Among the 29 patients who restarted HAART using an NNRTI-based regimen, however, 16 (55%) failed to achieve a viral load below 50 copies/mL.
Genotypic analysis in ten of the individuals failing NNRTI therapy showed that one patient had wild-type virus, one had an NNRTI-associated resistance mutation, and the remaining eight had NRTI resistance.
The investigators conclude that in HIV-positive patients with complete viral suppression, HAART should be discontinued cautiously when an individual has been taking an NNRTI or wishes to restart anti-HIV therapy using an NNRTI.
Further information on this website
Structured treatment interruption - overview of key research
Week on, week off treatment strategy buried at Paris conference - news story, July 17, 2003.
Barreiro PM et al. Negative impact of drug holidays in HIV-infected on non-nucleoside reverse transcriptase inhibitors. 43rd ICAAC, abstract H-857, September 14 - 17th, 2003.