Gilead's sofosbuvir and Bristol’s daclatasvir [=BMS-790052] could make a happiest couple in the world if Gilead did allow sofosbuvir to wed daclatasvir. Read today's PR. But, Gilead said the dowry is too expensive and prefers a home-grown boy NS5A inhibitor. So, Bristol decided to screen VX-135 as a potential mate for daclatasvir. I have a hunch that VX-135 is as safe if not safer, and as potent, as sofosbuvir.
There is a good reason to believe that inhibitors of NS5A and NS5B work together very well. A NS5A inhibitor is not just the disruptor of HCV replication complex. Just as protease inhibitors (like incivek) disrupt HCV's ability to evade host's immune response, NS5A inhibitors can also foil HCV's attempt to sabotage host's immunity, but in an independent pathway from protease inhibitors.
Successes of all-oral HCV's non-structural protein inhibitors validate the concept that the currently developed DAAs have the immunological mechanism components, so that they can effectively replace interferon and ribavirin.
Also this; The combination had previously demonstrated success in patients who hadn’t been treated before. Those who have failed Incivek or Victrelis are “perhaps the most difficult-to-treat population” and have no current options, said Mark Sulkowski, a doctor at Johns Hopkins University in Baltimore who presented the results