PR for an NDA does not necessarily indicate better chances for approval, but PR for an sNDA should, since it's just an expansion of the label - only if new safety issues popped up (like A-fib for R-IT) would you question whether PR is good or neutral. In any case, R-IT approval is a slam dunk.
P.S. Ignore JL's petty angry response - he's not looking at the question you asked from the correct perspective - you asked whether the PR would change the market's expectations for approval, NOT if R-IT will fail to gain approval - and based on today's action, the answer appears to be "yes" - stock wouldn't pop +12% if the market didn't believe receiving PR was a good indicator of approval. Unless it was just a short squeeze, of course.......won't know whether it was until tomorrow, but since 5/10/19 only one day has seen new shorts > short covers.