NorthWest Biotherapeutics Inc (NWBO)

[flipper44]

Pyrr,

They added the additional cohort (pseudo progression group) on May 2012 to expand the application for L. See the P.R.. To the best of my recollection, the unconfirmed document that passed this board's way some time ago, and then went into the ether, confirmed that the trial design was to then separately analyze the pseudo progression cohort once the primary group demonstrated statistically significant efficacy. Then the pseudo progression group stats, while a tertiary endpoint, would also be calculated as a whole with the primary group, but not for the purpose of establishing the primary endpoint. (But you would need enough data points from the pseudo progression group to do this, and since they started in May 2012, they may need to substantially enlarge their group to speed things up. In other words, the group needs to mature before it would start to show statistical separation. This can be done with time and/or by enlarging the group. Remember, the primary group did it with time and size, and they are a very mature cohort.)

(Interestingly, Ou recently pointed out there is precedent with the FDA in a similar sense, where the FDA changed the primary threshold for a subgroup. While i am not contending at all that this is being done here, I am contending that the pseudo progression group is far more important subgroup than many believe.)

While there is a chance you could be right that they are waiting for the secondary endpoint, which is overall survival in the primary group, I respectfully disagree. Besides, this would mean a continue, not a delay. IMHO, I suggest the long tail effect already established very significant efficacy in the primary treatment group OS.