February 24, 2009
In a poster presentation at CROI 2009 in Montreal, Canada, study data showed that people using the integrase inhibitor Isentress (raltegravir) developed similar rates of cancer as seen among people taking Sustiva or placebo. Cancer rates observed in 4 earlier studies of Isentress had raised concerns. A large analysis of 5 randomized, double-blind studies of the drug ease concern about cancer risks associated with its use.
Data from the 5 studies as well as an open-label phase and expanded access program, followed both treatment naiive and experienced individuals taking raltegravir. Three studies reported 48-week data in phase III and two studies reported 96-week data in phase II. In total, 1,039 people took raltegravir while 605 took either Sustiva or a placebo. Everyone was also on an optimal background regimen.
The definition for cancer was a broad and conservative one that included recurrences, non-melanoma skin cancers, and carcinoma in situ as well as a worsening of pre-existing cancerous conditions. Men comprised about 88% of the treatment experienced group and 81% of the treatment naive.
For the studies with 48 to 120 weeks of follow-up, cancer was reported at a lower rate for those on Isentress but it was not statistically different when compared to Sustiva or placebo. For the open-label phase, which included people with more advanced disease, the cancer rates remained similar to the controlled studies. The expanded access program with 24 weeks of follow-up in over 5,400 people, showed cancer rates similar to those in the ongoing controlled studies which, again, are showing no differences in the rates of cancer between those taking the drug compared to those on either Sustiva or placebo.