Tibotec Therapeutics has won approval in the USA for Prezista, a new HIV protease inhibitor for use in patients who have failed treatment with other antiretroviral agents.

Prezista (darunavir; formerly TMC114) was cleared by the US Food and Drug Administration on Friday for use in combination with another protease inhibitor, Abbott’s ritonavir, along with other antiretrovirals. Tibotec is a division of Johnson & Johnson subsidiary Ortho Biotech.

Ritonavir is commonly used in combination with other protease inhibitors because it inhibits metabolic enzymes involved in their breakdown, boosting levels of the active drugs in the blood and enhancing their anti-HIV effect.

Prezista will target protease inhibitor experienced HIV patients, a group which has been a particular focus of treatment with Boehringer Ingelheim’s Aptivus (tipranavir), approved in Europe last October and launched in the USA a year ago. This drug has similar labelling to Prezista and could feel the pinch now that a direct competitor in the salvage therapy end of the market will be introduced, according to analysts at Datamonitor.

Meanwhile, Prezista’s approval is expected to provide a boost for Roche’s entry inhibitor Fuzeon (enfuvirtide), which also tends to be use as salvage therapy in HIV patients who are failing their treatment regimens.

The FDA approval was based on evidence from two studies comparing the safety and effectiveness of the Prezista plus ritonavir combination with other ritonavir-boosted protease inhibitor combinations. Patients in both arms of these trials also used other anti-HIV agents - nucleoside reverse transcriptase inhibitors - with or without Fuzeon.

Data show that up to two-thirds of patients with extensive prior exposure to anti-HIV drugs achieved undetectable levels of virus (less than 50 copies of viral RNA per ml of blood) when darunavir was used alongside Fuzeon, a result that has never been seen before in this patient population.

Pricing welcomed

Meanwhile, the Fair Pricing Coalition, a group of HIV advocates, welcomed Tibotec’s decision to price Prezista “within pennies of the cost of the least expensive” of three other new drugs for HIV, which were each launched at a higher price than those that preceded it.

Tibotec “has finally reversed the juggernaut of higher pricing and acted as a responsible corporate citizen,” commented FPC spokesman Martin Delaney.

- Meanwhile, Boehringer Ingelheim recently decided to halt a trial of Aptivus plus ritonavir in treatment-naive HIV patients after the results showed it was less effective in the group than a comparator drug, Abbott’s Kaletra (lopinavir/ritonavir).