The NIH is stopping a clinical trial that uses Trizivir alone as a first treatment for patients with HIV who have not previously received therapy. Interim analysis shows that the arms of the trial where patients received efavirenz (Sustiva) as part of their regimen were more effective in controlling the disease.

News of the decision came in a March 10 memo to HIV/AIDS healthcare providers from the National Institute of Allergy and Infectious Diseases.

The Adult AIDS Clinical Trials Group (ACTG) study known as A5095 enrolled 1,147 antiretroviral-naive patients into the trial. One group received just Trizivir, a combination of the nucleoside analogs AZT, 3TC, and abacavir. Another group added Sustiva to the Trizivir, while a third went on a regimen of Sustiva and Combivir (AZT + 3TC).

When the independent Data Safety and Monitoring Board (DSMB) reviewed interim 32-week data on the ongoing trial, it found that 21% of the Trizivir group but only 10% of the Sustiva groups experienced virologic ‘failure.’ Failure was a defined very conservatively as a HIV viral load greater than 200.

The DSMB recommended that the Trizivir arm of the trial be stopped and patients offered alternative regimens. Patients in the two other arms of the study will be told that their regimen contains Sustiva and those arms of the trial will continue, to see if there are significant differences in outcomes. All of the patients will continue to be followed until the fall of 2004.

‘I’ve always been a little wary of triple nuke regimens,’ said Douglas Ward, a physician with a large HIV practice in D.C. ‘It’s easier for the virus to develop resistance mutations when you only use one class of drugs.’ He acknowledged that Trizivir is ‘incredibly well tolerated and easy to take,’ but other drug options also are becoming easier to take. Ward has used an induction/maintenance regimen where he starts patients on Trizivir and Sustiva, then after their viral load has been undetectable for a year, he is willing to drop the Sustiva. But he warns patients; if their viral load becomes detectable they will have to go back on a more powerful regimen.