Merck’s HIV Drug Shows Promise

Merck’s interim results from a dose-ranging Phase II trial of new integrase inhibitor MK-0518 showed that the oral drug — at all three doses studied (200 mg, 400 mg, and 600 mg orally twice daily) in combination with optimized background therapy (OBT) –had greater anti-retroviral activity than placebo with OBT. Study results also showed that MK-0518 in combination with OBT was generally well tolerated in these patients with advanced HIV infection who were failing anti-retroviral therapy (ART), who had viruses resistant to at least one drug of each of the three available classes of oral ARTs, and who had limited active ARTs as options for treatment.

Interim study results from a total of 167 enrolled patients showed that at week 16 the percent of patients achieving HIV RNA< 400 copies/mL ranged from 64% (18 out of 28 patients) to 84% (21 out of 25 patients) for MK-0518 plus OBT across all doses studied versus 22% (six out of 27 patients) for placebo plus OBT.

MK-0518 represents a new class of ART called integrase inhibitors that prevent the insertion of the HIV viral DNA into the human DNA genome. Inhibiting integrase from performing this essential function blocks the ability of the virus to replicate and infect new cells.