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Vertex Pharmaceuticals Inc. said collaborator GlaxoSmithKline plc is likely to file for approval of the HIV protease inhibitor GW433908 - which last month entered its third pivotal Phase III trial - by the end of the year in the U.S. and Europe.

"We've now got the preliminary analysis of the second of three pivotal Phase III studies," said Michael Partridge, associate director of corporate communications for Cambridge, Mass.-based Vertex.

Like the previous study, this one met its endpoints, he told BioWorld Today, adding that further details would be provided at one or more medical conferences in the second half of the year. Vertex moved the compound - a prodrug of the approved protease inhibitor Agenerase (amprenavir) - which it licensed to London-based GlaxoSmithKline, into Phase III studies in late 2000. (See BioWorld Today, Nov. 28, 2000.)

During Vertex's annual meeting, at which shareholders re-elected three directors and approved amendments to an employee stock purchase plan, the company further said it has agreed with partner Aventis SA, of Frankfurt, Germany, to push ahead with development of the oral interleukin-1 beta converting enzyme inhibitor pralnacasan in rheumatoid arthritis. Phase II trials of the drug also are planned in osteoarthritis, as well as other indications.

Pralnacasan emerged in April from a Phase II trial in RA, with positive results.

"We've independently communicated all of this [news about the drug pipeline, other than the early data from the second Phase III trial of GW433908], and it's been discussed previously," Partridge said.

Reiterating updates at the meeting provided "details to back up our assertion that we're progressing well," he added.

Vertex also rounded up for shareholders the advances made in its unpartnered programs.

A 60-patient, Phase II triple-combination study has begun of VX-497 (merimepodib), an oral inhibitor of inosine monophosphate dehydrogenase (IMPDH) for hepatitis C. Patients with HCV in Europe will be treated with either VX-497 in combination with pegylated interferon and ribavirin, or placebo in combination with pegylated interferon and ribavirin. The six-month study carries an optional six-month extension phase.

The enzyme IMPDH is essential for production of nucleotides, and inhibiting it may block DNA synthesis, important to lymphocyte proliferation as part of the immune response. A Phase II trial of a second-generation oral IMPDH inhibitor for psoriasis, VX-148, is expected to start in the second half of the year. The Phase I dose-ranging trial began in December 2000.

"The mechanism is essentially immunosuppressive, targeting selected lymphocyte populations," Partridge said. "It's a fairly broad mechanism and, in psoriasis, you can get fairly specific readouts quickly, and this is a compelling opportunity."

Vertex plans this quarter to begin a Phase I study of VX-702, a second-generation p38 MAP kinase inhibitor targeting RA. The trial is in healthy volunteers, and the company wants to expand upon the clinical proof-of-concept data from the Phase II clinical trial of its lead p38 MAP kinase inhibitor, VX-745, in RA. The drugs are believed to have applications in various inflammatory and cardiovascular diseases.

In 2000 and 2001, the company pushed nine new drug candidates into preclinical development, and expects in 2002 to choose four new preclinical drug candidates for development.

"We think that's a distinguishing characteristic of Vertex," Partridge said, adding that the company has "always pursued a portfolio approach," for various practical reasons - not the least of which is that "drug development is a risky business."

Vertex's stock (NASDAQ:VRTX) closed Friday at $19.51, up 98 cents.

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