In a normal trial, where the sentence is not death within a few months, you cannot tell as the trial is blinded. However, given the disease, and the fact that some of the patients were still receiving treatment, it becomes apparent that the treatment is working. I’m sure it became evident early on that the treatment was working..
It probably tells you that even the blinded data is so good (and they know more of it than we do - like haw many are still alive today) the success is highly likely when they unblind and they want to make sure they are holding as many loto tickets as they can muster.
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