Washington Editor

Vertex Pharmaceuticals Inc. and partner GlaxoSmithKline plc said preliminary analysis of a Phase III study of the investigational protease inhibitor GW433908 showed the study arms met their endpoints.

This data, in conjunction with positive data from two previous Phase III pivotal trials, will be submitted for regulatory approval sometime during the fourth quarter, Michele Karpf Belansky, spokeswoman for Cambridge, Mass.-based Vertex, told BioWorld Today.

GW433908, also referred to as 908 or VX-175, was discovered by Vertex and later licensed to London-based GSK. The drug is included in the same partnership that produced Agenerase (amprenavir), another HIV product co-promoted by the companies.

Preliminary data results were analyzed at the 24-week point in the Phase III trial referred to as CONTEXT, an open-label study of more than 300 treatment-experienced patients at 80 research centers worldwide. CONTEXT compared once-daily and twice-daily dosing of 908 in combination with ritonavir to lopinavir/ritonavir (Abbott Laboratories' Kaletra). The companies will release 48-week data at a later time.

"This data, like that previously released, looks good and continues to suggest that 908 is approvable," research notes released by Philip Nadeau, of SG Cowen in New York, said.

CONTEXT joins the other two Phase III studies, NEAT (study 30001) and SOLO (study 30002), which also met their endpoints at 24 and 48 weeks. (See BioWorld Today, Sept. 30, 2002, and May 20, 2002.)

Nadeau expects a mid-2003 FDA approval on 908, but cautions that the HIV market has become increasingly crowded. "Therefore, the exact profile of the drug that emerges from all of 908's Phase III trials will be very important for its competitive positioning," he said. "While last night's top-line results were encouraging, Abbott's Kaletra has quickly become the HIV protease inhibitor to beat and therefore, the detailed results from 908's CONTEXT trial are perhaps most important for its position in the market."

Nadeau said 908 could become a major competitor if CONTEXT demonstrates that 908's efficacy is equal to Kaletra, and if it has distinct safety and convenience advantages.

He estimated that Vertex would receive a mid-teens royalty on worldwide sales.

Vertex's stock (NASDAQ:VRTX) closed Thursday at $19.30, up 35 cents.