NorthWest Biotherapeutics Inc (NWBO)

[CDRD]

I think there is an easier explanation for the mOS than has been offered to date.

If NWBO stops the trial at precisely 233 OS events, the median will be the 117th patient (when all the deceased patients are rank ordered by how long they lived). If NWBO waits unitl 234 OS events, then the median will be the average of the 117th patient and the 118th patient. If they wait for 235 OS events, the median will be the 118th patient, and so on.

So, Senti and others are correct that the more OS events that occur the more the mOS shifts to the next patient---these differences may be small but that is how medians work in this case.