Bitopertin addendum

In looking at the Roche bitopertin trial design, the six month readout in the negative symptom trial protocol was the primary endpoint, not an interim measure. The second six month timeframe was an ‘extension within protocol.’ The suboptimal responder trials focused upon positive symptoms appear to have their primary endpoint readout at three months, with a nine month extension. Thus one might shave off a little time from the previous post’s guesstimates on readout timing for those three trials, though of course, we have no definitive information about rate of enrollment– we had heard rumors that enrollment was going slowly.

The other unknown is whether any effect might be expected on cognitive symptoms. From the Phase II results we have seen, we would suspect no significant differentiation was found there, since the CNS-VitalSigns neuropsych results were the one category not highlighted. Thus it is unlikely that a Phase III effect will fortuitously emerge, though Roche will dig deep to see if there is anything to be found.

It is also worth noting that, while the PhII used doses of 10, 30, and 60mg (with 60mg doing the worst), this Phase III program did not go above 20mg.