New HIV drugs

A study has shown that the experimental integrase inhibitor elvitegravir is as effective as raltegravir (Isentress), currently the only licensed drug in this class. The research involved people with extensive resistance to anti-HIV drugs.

Treatment consisted of elvitegravir or raltegravir, in combination with a ritonavir-boosted protease inhibitor and another active anti-HIV drug. After 48 weeks, equal proportions (59%) of people taking elvitegravir and raltegravir had an undetectable viral load. CD4 cell gains were also comparable. Both drugs were equally well tolerated, and rates of side-effects were similar.

Elvitegravir is taken once a day whereas raltegravir is a twice-daily therapy.

Another new integrase inhibitor is being developed. Called dolutegravir, it will be the first once-daily integrase inhibitor that will not require a boosting agent. Compared to standard-of-care treatment containing efavirenz, treatment with dolutegravir was just as potent, but with fewer side-effects.

Dolutegravir is being tested in phase 3 trials with a view to licensing in 2013, and a fixed-dose combination pill that also contains abacavir and 3TC is planned.

Lersivirine, a new drug in the NNRTI class being developed, was found to be as effective as efavirenz (Sustiva), in a phase 2b clinical trial.

After a year of treatment, 79% of people treated with lersivirine had an undetectable viral load compared to 89% of people treated with efavirenz. CD4 cell count increases were good, regardless of which NNRTI patients received. Lersivirine didn’t appear to work as well in people with a high viral load (above 100,000 copies/ml at baseline).

Rates of neuropsychiatric side-effects were lower among the patients taking lersivirine, but nausea was more common.

Phase 3 trials examining the safety and effectiveness of lersivirine are now planned, but as all these drugs are still being investigated, it'snot yet known if and when they'll be available for patients.