Positive News For Patients With Highly Resistant HIV Infections

Advances in antiretroviral therapy have prolonged the lives of many patients with human immunodeficiency virus, transforming the disease from fatal to chronic. But a sizeable number of HIV patients are developing or acquiring highly drug-resistant HIV. But a study led by Roy T. Steigbigel, M.D. - a professor at Stony Brook University Medical Center found that Isentress, when combined with other anti-HIV medications, demonstrated superior suppression of HIV-1 in patients with highly resistant virus compared with placebos.

"This is important because people who have been infected with HIV for a fair amount of time have no control anymore of their bodies and they can get very sick and die...(Isentress) allows patients to get some control for a period of time," Steigbigel said. Isentress is a type of medicine called an integrase inhibitor. Integrase is a protein that HIV needs to insert its viral genetic material into the infected cell, and the inhibitors work by blocking the integrase.

In most patients with highly drug-resistant HIV, the resistance develops from years of using HIV medications and the resulting mutation of the virus. Even people who are newly infected can be infected by a drug resistant strain of HIV, rendering useless many of the front line drug therapies.

In the study, patients who received Isentress had higher rate of virologic suppression than those who received the placebo, and the overall suppression rates of viral suppression are among the highest reported for those infected with highly resistant HIV. "The breakthrough is that the drug acts on new targets," Steigbigel said. Targets are the part of the virus where it replicates itself, resulting in higher chances of replications.

Steigbigel's study evaluated the activity of Isentress among 699 patients infected with HIV. Only patients with severely drug resistant HIV, or those documented with three classes of HIV drugs, were eligible for the study. According to the study, Isentress worked best when combined with two other HIV drugs. Steigbigel also noted that the multi drug therapy helped the immune system to rebound in some patients, with increases in CD4 counts as compared to the placebo group.

However resistance to Isentress requires only a single point of mutation, and among the 94 subjects in the study who experienced drug resistance during the study, about two thirds showed resistance by week 48. As with any HIV medication, Irregular use of the medication can quickly result in resistant strains of HIV, with resistance occuring as quickly as "months.", according to Dr. Steigbigel.

Isentress, a product of Merck and Co. was approved for clinical use on October 12, 2007 by the FDA. Courtesy The Statesman newspaper of Stony Brook University.