For difficult indications, the push for product development must be balanced by the advent of proper tools to evaluate lead compounds. If it is not, the likelihood that either the target or the compound cannot be properly validated increases, translating to poor clinical efficacy.

A case in point is hepatitis C virus. Last week ViroPharma Inc. (VPHM, Exton, Penn.) and partner Wyeth-Ayerst Laboratories, a division of American Home Products Corp. (AHP, Madison, N.J.), halted development of their lead HCV compound, VP 50406, after Phase IIa data failed to show significant antiviral activity (see B17).