NorthWest Biotherapeutics Inc (NWBO)

[flipper44]

The logical take would be to assume that once they had enough patients initially screened to likely enroll 348, they would halt screening new patients. Then, a few months down the road, when they enrolled every eligible patient in the pipeline, they would note on clinical trials.gov that they were no longer enrolling new patients.

Had they just kept conducting screening on patients until the time they reached full enrollment, they would have had a sizable number of eligible patients that also needed to be enrolled because their tumors and blood were already sent off to a lab to make lysate pulsed DCs.

Over-enrollment in an autologous immunotherapy cancer vaccine would be counter productive, because you might be capturing too many progressors from the placebo patients to reach 248. Over-enrollment is also unnecessarily expensive.

If you note, there are ideally supposed to be 116 placebo patients and 232 treatment patients enrolled. 248 events seems clearly, at least partially, meant to make certain a median PFS was reached in the treatment group, EVEN IF all placebos evented.

If the placebos evented too fast in relation to the treatment group, and if over-enrollment was allowed, you might actually be short a PFS median for the treatment group once 248 PFS events were reached.

With all this in mind, they are still taking at least a month longer to event even considering the month fudge factor NWBO talked about (see 8-k October, 6 2015) a year before due to the screening hold.

Many trials end up over-enrolling, but when cost, ethics and statistical analysis could be compromised, it makes sense to attempt not increasing the number of placebos and decrease the number of treatment patients in the 248 PFS event final analysis group. It makes sense to avoid over-enrollment.