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Four days on, three days off HIV treatment controls viral load in French pilot study
Keith Alcorn, 2016-11-03 06:50:00
An experimental `four days on, three days off`
antiretroviral regimen kept viral load fully suppressed in 96% of people for 48
weeks in a French study presented at the International Congress on Drug Therapy
in HIV Infection in Glasgow last week.
The study recruited people whose viral load had been fully suppressed on treatment for a median of four years, not people who had started treatment recently.
Although people living with HIV are recommended to take
antiretroviral drugs every day as prescribed, there is evidence from therapeutic
drug monitoring that sufficient blood levels of many antiretroviral drugs
persist for several days after dosing, keeping HIV under control even when a
single dose is missed.
Several clinical trials have investigated whether it is
possible to miss two consecutive doses and take a weekend off treatment. The FOTO
study found that taking two days off treatment each week maintained viral
suppression in people taking efavirenz-based treatment, and a larger study conducted in
Uganda found it was just as effective as continuous treatment. The BREATHER
study in adolescents and young people found that taking two days off
efavirenz-based treatment each week was just as likely to keep viral load
suppressed as daily treatment, and was highly acceptable to this group of
Sponsored by the French national HIV research agency ANRS,
the ANRS-162-4D trial was designed to test whether four days on treatment and
three days off treatment each week maintained viral suppression in people with
undetectable viral load. A four-day regimen may suit those with a standard
working week who do not wish to think about taking medication over the weekend.
In the study participants were offered two patterns of pill-taking: take
medication each day from Monday to Thursday, or take medication each day from
Tuesday to Friday. The regimen also reduces the cost of treatment.
The study recruited 100 people taking a three-drug regimen
of two nucleoside reverse transcriptase inhibitors (NRTIs) and either a boosted
protease inhibitor (29%) or an NNRTI (71%). At the time of study entry participants
had undetectable viral load for a median of four years.
Participants were predominantly male (82%) and white (81%).
Approximately two-thirds were men who have sex with men.
Treatment failure in this study was defined as two
consecutive viral loads above 50 copies/ml two to four weeks apart, or discontinuing
the study strategy for more than one month. After 48 weeks of follow up 96 of
100 participants had maintained viral suppression below 50 copies/ml. Three
participants experienced virologic rebound and another discontinued the treatment
strategy after four weeks.
Whereas short interruptions have been thought to maintain
viral suppression because drug levels persist, this study found that even where
drug levels declined to barely-detectable levels by the end of the
off-treatment period, viral suppression was maintained.
Etravirine, taken by five participants, was the only agent
that maintained effective concentrations by the end of the off-treatment period,
but this observation may have been a consequence of the small number of people
treated with the drug. Average levels of efavirenz (40 persons), rilpivirine
(26), darunavir (15), atazanavir (15) and lopinavir (1) were sub-therapeutic by
the end of the off-treatment period.
The researchers reported on drug levels of the protease
inhibitor or NNRTI in the regimen but did not evaluate the levels of the
nucleoside reverse transcriptase inhibitor (NRTI). Ninety of the 100
participants were taking tenofovir as part of their regimen. Tenofovir concentrations
take 50 hours to decline by half from peak levels in cells, resulting in
prolonged antiviral activity, suggesting that tenofovir may have contributed to viral suppression in the absence of other drugs.
Intracellular DNA levels, indicating the size of the HIV reservoir in cells, were relatively low, at 2.4 log, both at baseline and after 48 weeks of the treatment strategy. There is some evidence that a lower level of HIV DNA is associated with slower viral rebound after treatment interruption.
Virologic rebound occurred in three patients, two taking
abacavir-based treatment in combination with a boosted protease inhibitor.
Rebound was detected 4, 12 and 40 weeks respectively after starting the new
regimen. In one case the pattern of rebound suggested a viral blip – viral load
was 124 copies/ml at the week 12 visit and had fallen to 55 copies/ml when
tested again nine days later. In the two other cases, viral load rose above 200
copies/ml but was subsequently resuppressed.
All participants who experienced rebound reported 100%
adherence to the study strategy.
An adherence sub-study, previously presented at the 21st
International AIDS Conference in Durban in July 2016, examined adherence by
electronic pill bottle caps and self-report in 26 participants. The sub-study
found that MEMS caps were opened on exactly four days a week in a median of 44
weeks during the study, but were opened less frequently than four days a week in a
median of four weeks during the study. Self-report of adherence during the previous week showed
that 21% reported taking fewer than 80% of their medication on at least one
visit and only 6% reported 100% adherence at one visit.
Liver enzyme levels (AST, ALT and GGT) declined significantly during the follow-up period. A modest but statistically significant increase in glycaemia was observed. Cholesterol and triglycerides did not change significantly. Seven serious adverse events occurred during the study but were not considered to be treatment-related.
ANRS is planning a larger follow-up study, QUATUOR, which will randomise 640
people to continuous or four-day-a-week treatment. The trial will include
people taking integrase inhibitors in order to reflect newer treatment
recommendations, and will follow patients for up to two years to check virological
outcomes and impact on side effects and quality of life.