July 31, 2009

Isentress Without a Protease Inhibitor Is Effective for Treatment Experienced Patients

It might not be necessary to combine the integrase inhibitor Isentress (raltegravir) with a protease inhibitor (PI) in treatment experienced people with HIV, according to a study published at the Fifth International AIDS Society (IAS) Conference on HIV Pathogenesis, Treatment and Prevention in Cape Town. People on an Isentress regimen without a PI maintained undetectable virus levels at about the same rate as those on a PI.

Raltegravir has proved to be one of the most potent and safe of the newest antiretroviral (ARV) drugs to be approved in recent years. It was approved in 2007 for people who had taken and become resistant to many of the ARVs then available, and it was also recently approved for people new to treatment. For treatment experienced people, however, most of the clinical trials so far have looked at regimens that also included Isentress and a PI. This is key, because many studies have found that including a Norvir (ritonavir)–boosted PI increases the chance that someone will achieve an undetectable level of HIV.

To determine whether a PI was necessary with Isentress for treatment experienced patients, Calvin Cohen, MD, from the Community Initiative on AIDS in Boston recruited 442 of treatment experienced patients into a trial that randomized people to start a new regimen that included Isentress with a PI or Isentress without a PI. In all, 330 received a protease inhibitor and 112 did not. The average number of drugs in the new regimen that were still active against HIV was two, including Isentress—and a PI in those who were taking one.

Cohen’s team found that people not taking a PI did about as well as those taking a PI. After 24 weeks, of those patients who had reached this point, 75 percent taking a PI achieved a viral load less than 75 copies, while 64 percent of those not taking a PI reached a viral load less than 75 copies. With the small number of people who reached the 24-week point, which was about a third of patients in both groups, it appears that the difference was large enough that it did not occur by chance.

Longer-term data from this study, with all of the patients included, will be needed to determine whether a protease inhibitor should be taken with Isentress.

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Curtis Arthur Strack, Alexandria, 2009-08-04 13:47:39
Been on Isentress for about a year. 2 drugs in my previous cocktail (Sustva, Invarase) begin to become of less and less use to me. My Dr. of 19 years threw out those andZiagen. I now take Prezista, Isentress Norvir and Epzicom. My t-cells are 600 and no VL) GO Isentress. CAS