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May 27, 2008

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Monitoring Board Recommends
Stopping Experimental Treatment Regimen in
International Study of Patients New to HIV Treatment

An independent Data and Safety Monitoring Board (DSMB) has determined that the experimental, once-daily antiretroviral drug regimen of emtricitabine, atazanavir and didanosine enteric-coated (ddI-EC) is inferior to a standard antiretroviral drug regimen and therefore should be discontinued in an ongoing clinical trial. The National Institute of Allergy and Infectious Diseases (NIAID), the part of the National Institutes of Health that oversees the trial, concurs with this recommendation and has stopped this component of the study.

This development arose from the DSMB’s recent review of safety and efficacy data from a Phase IV clinical trial sponsored by NIAID. The trial is examining whether certain regimens of antiretrovirals taken once a day are at least as good as a standard antiretroviral regimen containing a drug combination taken twice a day. The study involves 1,571 HIV-infected volunteers on four continents who were randomly assigned to take one of three drug regimens:

  1. lamivudine/zidovudine taken twice daily + efavirenz taken once daily (the standard, control regimen)
  2. emtricitabine + atazanavir + ddI-EC (an experimental regimen taken once daily, with atazanavir taken separately from ddI-EC)
  3. emtricitabine/tenofovir + efavirenz (an experimental regimen taken once daily)

The DSMB found conclusive evidence that the second regimen, emtricitabine + atazanavir + ddI-EC, is inferior to the control regimen primarily because it is less effective at controlling HIV. Based on this finding, the decision has been made to discontinue the emtricitabine + atazanavir + ddI-EC component of the study. All study participants are being notified of the development.

Those participants who have been taking emtricitabine + atazanavir + ddI-EC are being advised to consult their study physicians to determine to which alternative regimen they should switch and how best to proceed with their antiretroviral therapy. The study team is continuing follow-up of all volunteers, including those in the second group who are switching to a different antiretroviral drug regimen.

The study team finished enrolling all volunteers in July 2007 and is gathering data through follow-up visits with the study participants, who are located in Brazil, Haiti, India, Malawi, Peru, South Africa, Thailand, the United States and Zimbabwe. The study is known as ACTG 5175 and is titled “Evaluation of Once-Daily PI and NNRTI Regimens as Initial HIV Therapy in Individuals from Resource-Limited Settings.”

Media inquiries can be directed to the NIAID Office of Communications at 301-402-1663,

NIAID conducts and supports research—at NIH, throughout the United States, and worldwide—to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID Web site at

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit

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Last Updated May 27, 2008