>what are the chances the vrtx hcv candidate [VX-950] may run into "issues" given how far down the road they are in their trial.<
Low chance, IMO. One risk, which applies more strongly in the real world than in a clinical study, is that patients will not adhere to the thrice-daily dosing schedule with the required degree of obsession. Given the short intracellular half-life of VX-950, missing doses could lead to the generation of resistant HCV strains. This risk will probably increase to some degree if VX-950 is being used in a regimen that does not include ribavirin or another direct antiviral.
>what are the chances the idenix hcv candidate [NM283] may run into "issues" given how far down the road they are in their trial.<
Medium risk in the treatment-naïve setting, and high risk in the treatment-refractory setting, IMO. The reason for this disparity is that the 200mg once-daily dose seems to be sufficient to reduce viral load in the treatment-naïve setting, but it is not enough to reduce viral load in the treatment-refractory setting. Doses higher than 200mg/day may be problematic due to GI side effects. Regards, Dew
p.s. Please note that IDIX’s lead drug is the one for HBV (Telbivudine), not the one for HCV (NM283).