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
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."
NIAID is a component of the National Institutes of Health, an
agency of the U.S. Department of Health and Human Services. NIAID
supports basic and applied research to prevent, diagnose and treat
infectious diseases such as HIV/AIDS and other sexually transmitted
infections, influenza, tuberculosis, malaria and illness from potential
agents of bioterrorism. NIAID also supports research on transplantation
and immune-related illnesses, including autoimmune disorders, asthma
and allergies. Press releases, fact sheets and other NIAID-related
materials are available on the NIAID Web site at http://www.niaid.nih.gov.
Reference: M Dybul et al. A proof-of-concept study of short-cycle
intermittent antiretroviral therapy with a once-daily regimen of
didanosine, lamivudine, and efavirenz for the treatment of chronic
HIV infection. Journal of Infectious Diseases 189(11):1974-82 (2004).