Firstly, you don't know where those 90 patients came from in the enrollment ramp. Secondly, even if they all came from the end that would mean the 30% of everyone who is supposed to make it to 2 years was all clustered together. What are the chances that instead of it being 1 in every 3 making it to two years, none of the first 200 did, but it was all 100 right at the end?
Seems to me that if it all isn't illegal wash trading, then someone big is taking the other side of these trades to accumulate.