Progress With Gilead Sciences' Antivirals

Gilead Sciences' nucleotide compounds have been shown to inhibit thereplication of a number of viruses, including human papillomavirus, HIV, cytomegalovirus and Kaposi's sarcoma herpesvirus, according to new data presented at the 4th Conference on Retroviruses and Opportunistic Infections held in Washington DC last month.

In a Phase I/II trial of Forvade (cidofovir gel) in 61 AIDS patients with refractory genital warts, 66% experienced lesion reduction, with 18% of these seeing complete clearance of the warts, and 48% partial clearance, defined as a 50% or greater decrease in wart size. Mild-to-moderate adverse reactions were recorded at the site of application, but there were no systemic side effects.

The company has also identified an oral prodrug of PMPA, an antiviral found to be effective in the prophylaxis and treatment of simian immunodeficiency virus, the primate model of AIDS. In preclinical trials, the prodrug demonstrated oral bioavailability of around 30%, and in cell cultures has proven more effective against HIV than the original PMPA. An injectable formulation of PMPA is currently at the Phase I level of development, with the oral prodrug expected to begin human trials by mid-1997.