By Debbie Strickland

Vertex Pharmaceuticals Inc.'s lead product, amprenavir, performed well in two Phase II trials, one pairing the anti-HIV product with approved protease inhibitors and the other combining the drug with an experimental nucleoside analogue reverse transcriptase inhibitor.

Formerly know as 141W94 and VX-478, amprenavir is an anti-HIV protease inhibitor partnered with Glaxo Wellcome plc, of London, and Kissei Pharmaceutical Co. Ltd., of Matsumoto, Japan.

Vertex and Glaxo Wellcome presented preliminary data from the two open-label Phase II trials Monday at the 5th Conference on Retroviruses and Opportunistic Infections, in Chicago. The trials are part of a broad Phase II program combining amprenavir with an array of HIV therapies. In addition, three Phase III trials are under way in preparation for an expected third-quarter new drug application with the FDA.

The 34-patient double protease inhibitor study's four arms combined amprenavir with nelfinavir (Viracept), indinavir (Crixivan), saquinavir (Invirase), and with the nucleoside analogues 3TC (Epivir) and AZT (Retrovir). AZT and 3TC are sold by Glaxo. Nelfinavir is made by Agouron Pharmaceuticals Inc., of La Jolla, Calif.; indinavir is manufactured by Merck & Co., of Whitehouse Station, N.J.; and saquinavir is produced by Roche Holding Ltd., of Basel, Switzerland.

The 16-week results in the 20 evaluable patients are promising, Vertex reported:

* The amprenavir and indinavir combination produced median viral load drops of 3.75 logs, with five of six patients having undetectable levels of virus (less than 400 copies per milliliter).

* The amprenavir-saquinavir arm showed a median 2.94 log drop in viral load, with all five patients having undetectable levels of virus.

* The amprenavir-nelfinavir arm produced a median 1.84 log drop in load, with three of six patients having undetectable virus.

* The amprenavir-3TC-AZT arm showed a median viral-load-drop of 2.79 logs, with two of three patients having undetectable virus.

The second study presented Monday focused more on Glaxo's abacavir (formerly 1592), a nucleoside analogue reverse transcriptase inhibitor. Amprenavir was one of five protease inhibitors tested with abacavir.

Patients in the abacavir-amprenavir group experienced the second-largest median decrease in viral load — 2.42 logs — with 11 of 13 having undetectable levels of virus. Only the abacavir-nelfinavir arm did better, with a median decline of 2.49 logs, with seven of nine patients having undetectable virus.

Shares in Vertex (NASDAQ:VRTX) closed Monday at $38.125, down $1.125. *