Weekly cycles of once-daily anti-HIV drugs could reduce cost of HIV
treatment

In a small study conducted at the U.S. National Institutes of Health
(NIH), researchers have shown that it may be feasible to treat
HIV-infected patients with a simple, once-daily regimen of anti-HIV
drugs given in pre-planned, 7-day-on, 7-day-off cycles. This approach
is known formally as ''short-cycle structured intermittent
antiretroviral therapy'' (SIT) or colloquially as the ''7-7''
approach.

''Our data suggest that the 7-7 approach, used with well-chosen drug
regimens in settings where patient adherence is high, could be a
powerful and cost-effective tool in treating HIV-infected
individuals,'' says study author Mark Dybul, M.D., of the National
Institute of Allergy and Infectious Diseases (NIAID), a component of
NIH. ''By using half as much antiretroviral medication, drug costs are
reduced and drug-related toxicities may be less in the long run.'' He
adds, ''The 7-7 approach may have particular relevance to
resource-poor countries around the world.''

Dr. Dybul, NIAID Director Anthony S. Fauci, M.D., and their colleagues
report their findings in the June 1, 2004 issue of the Journal of
Infectious Diseases.

In their study, the NIH investigators enrolled eight HIV-infected
people who had been successfully treated with a combination of three
or more antiretroviral drugs for at least 6 months. Upon enrollment,
the patients began following a treatment regimen of 7 days without
antiretroviral therapy, followed by once-daily treatment with the
drugs didanosine (ddI), lamivudine (3TC) and efavirenz for 7 days,
followed by 7 days off the antiretroviral drugs, repeating the off-on
cycle for more than a year. One patient withdrew from the study for
personal reasons at week 24; the other seven patients receiving the
7-7 regimen maintained undetectable levels of HIV in their bloodstream
[<50 HIV RNA copies per milliliter] for 60 to 84 weeks. During this
period, the study volunteers had no significant changes in their CD4+
T-cell counts, and no evidence of resistance to the antiretroviral
drugs in their treatment regimen.

Unlike a previous NIH 7-7 study using as different drug regimen, the
investigators did not observe transient ''blips'' during which
bloodstream levels of HIV rise above detectable levels, a finding they
attribute to the persistence of efavirenz in the blood throughout the
7-day-off-therapy cycle in the current study.

The authors note that strict adherence to the prescribed regimen in
the 7-7 approach is necessary. Of note, the once-daily regimen used by
Dr. Dybul and his colleagues may allow for enhanced adherence compared
with the twice-daily regimen that the researchers used in a previous
study.

In their paper, the authors conclude: ''If the safety and efficacy of
short-cycle SIT ultimately are demonstrated in clinical settings, it
might prove to be an important strategy to expand therapy in
resource-limited settings. In this regard, randomized, controlled
clinical trials are being conducted in various sites in the United
States and other countries to evaluate the clinical usefulness of
short-cycle SIT.''