The US Food and Drug Administration is expected to approve the first integrase inhibitor, Merck’s product raltegravir, by mid-October, Merck announced yesterday.
Raltegravir, which will be marketed under the brand name Isentress, has been granted a priority review by the US FDA, which means that the licensing application must be reviewed within six months. Merck said yesterday that it expects the FDA to complete the review by mid-October.
The announcement means that two new drugs for treatment-experienced patients could become available in the United States wihin weeks of each other. Pfizer’s maraviroc (Celsentri), a drug which blocks HIV entry into CD4 cells, is currently under discussion with the FDA but has been delayed from approval because more safety data are required. Marketing approval is likely within the next few months, Pfizer said last week.
Raltegravir is the first inhibitor of HIV’s integrase enzyme, which acts to integrate HIV’s genetic material into human immune cells. Studies in highly treatment-experienced patients have shown very promising results, with nearly two-thirds of patients achieving an undetectable viral load after 16 weeks when the drug was added to a background regimen chosen with the aid of drug resistance testing.
Results from a 48 week study in treatment-naïve patients confirming the drug’s potency and very rapid suppressive effect on viral load are due to be presented next month at the International AIDS Society Conference on HIV Treatment and Pathogenesis in Sydney.