NIAID Halts ACTG 5175 Clinical Trial Arm Receiving Once-daily Atazanavir (Reyataz), Emtricitabine (Emtriva), and Didanosine (Videx EC)

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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 [Sustiva] 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) [EDITOR'S NOTE: this regimen, which includes the 3 drugs in the Atripla combination pill, is no longer considered experimental.]

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."