Have u seen their R788 phase2 trial doc, here is the link..
50mg is worse than 0mg, 100mg had too many side effects. Can you imagine 75mg is a magic number? Even the human weight, stomach and liver absorption have bigger variations. Fortunately, FDA may not call a stop to RIGL incoming phase IIb. But, who knows, FDA did stop some phase 2's and 1's.