Phase III trials for Vertex/GSK's GW433908

Vertex Pharmaceuticals has announced that a Phase III trial of GW433908,an HIV protease inhibitor, has begun in patients who have been previously treated with at least one non-nucleoside reverse transcriptase inhibitor and one or two protease inhibitors, and who have evidence of protease inhibitor susceptibility. The drug, discovered in collaboration with GlaxoSmithKline and licensed to the latter firm, will be tested in doses of either: one 700mg tablet twice a day in combination with 100mg of Abbott Laboratories protease inhibitor ritonavir; or as 1,400mg (two tablets) once a day in combination with 200mg ritonavir. It will be compared with Abbott's new fixed-dose product, Kaletra (400mg lopinavir/100mg ritonavir), given twice a day. Patients will also receive two nucleoside reverse transcriptase inhibitors. The trial will asses the antiviral efficacy and safety of the three regimens at 24 and 48 weeks.