Second study shows drug holidays
associated with better salvage response
Twenty six out of thirty nine Frankfurt patients who took a drug holiday
before starting a salvage regimen experienced the disappearance of
drug-resistant virus and a viral load fall of close to 3 log when they
eventually started a mega-HAART salvage regimen of three to eight drugs.
In contrast, those who maintained drug resistance despite a drug holiday
experienced an average viral load fall of 0.78 log, and only one had viral load
below 500 copies after six months, compared to 19 out of 24 of the
responders.
The report was presented to the Second International Workshop on Salvage
Therapy for HIV Infection, held in Toronto on May 19-21.
However, a drug holiday in this cohort was not without its risks, observed
Professor Brian Gazzard, commenting on median CD4 count falls of 89 cells/mm3
and a median viral load increase of 0.71 log. CD4 count declines of this
magnitude might be hazardous for individuals with low CD4 counts no longer
receiving prophylactic or maintenance treatment.
These findings support those of another non-randomised study of mega-HAART
salvage, conducted by the Royal Free Centre for HIV Medicine. Dr Mike Youle told
the Salvage Workshop that the response to a salvage regimen of up to six drugs
was significantly influenced by the number of months an individual spent off
therapy before commencing the mega-HAART salvage regimen. This data was
previously presented to the RIGHT meeting in Washington DC, in April 1999.
Miller V et al. Mega-HAART, resistance and drug
holidays. Second International Workshop on Salvage Therapy for HIV Infection,
Toronto, abstract 030, 1999.
Youle M et al. Surrogate marker responses to
multi-drug combinations comprising hydroxyurea, efavirenz, double protease
inhibitors and nucleoside analogues in protease inhibitor failures. Second
International Workshop on Salvage Therapy for HIV Infection, Toronto, abstract
018, 1999.
CD4 response on HAART predicts viral rebound
risk
The better the CD4 reponse on HAART, the lower
the risk of viral load rebound, according to a report by Dr Veronica Miller to
the Second International Workshop on Salvage Therapy for HIV Infection, held in
Toronto on May 19-21. Individuals who gained more than 200 cells within 36 weeks
of commencing a new regimen were half as likely to experience viral rebound as
people who experienced little or no change in their CD4 count (p = 0.003).
Baseline CD4 count also had a significant effect: people who started a new
regimen with CD4 counts below 100 were twice as likely to experience rebound as
those who started a new regimen whilst their CD4 count was above 500, and were
50% more likely to experience rebound compared to those with a CD4 around 300
cells.
No other factors (including baseline viral
load, time to suppression of viral load below 500 copies, treatment experience
or the number of new drugs started) proved so significant in determining the
risk of rebound, leading the authors to speculate that CD4 cells (and their
replenishment) may play a more significant role than previously thought in
controlling viremia in people on HAART.
Miller V et al. CD4 count: predictor of
duration of HAART-induced suppression of virus load. Second International
Workshop on Salvage Therapy for HIV Infection, Toronto, abstract 030,
1999.