That’s painting with too broad a brush, IMO. Clearly, not all purine nukes are toxic or companies wouldn’t waste time developing them or waste money licensing them. VRTX could yet have a viable dual-nuke combination for HCV with the two drugs licensed from Alios; although there aren’t yet any clinical data on this combination, it’s reasonable to assume that the combination performed well enough in preclinical models that it will eventually be tested in humans.
p.s. Viread, one of the constituents of the dual-nuke product, Truvada, is a purine nuke. So is ribavirin.
Fair points. Not saying they can't be successful, of course, as we just need to see longer-term data. But, perhaps I should have stated it as the fairly recent issues involving the purines PSI-938 and the former INX-189 now at least heighten the risk with VRTX's in-house nuke program.
P.S. I just listened to ACHN's presentation at JMP and ACH-1625 is now known as sovaprevir. Kishbauch said to think "SVR" when you hear the name. LOL