GILD thinks that high rate of virological failure seen in the completed phase-3 trials could have resulted from low compliance of patients, who had to take many pills a day (trials were double blinded and placebo controlled). In the new Bitripla vs.Atripla every one gets fixed-dose once a day and I believe the B is a smaller pill than A (because TMC278 25 mg is smaller than 600 mg for Sustiva), so it's an open trial and everyone knows what they are getting.