If you want to spin this in a negative way, one could say that ARIA is calling the CC to give investor confidence a boost by annnouncing the start of a pivotal trial, because they know that negative news on Rida is coming soon after.
I think rkrw is right that if the CC is only to announce the start of a pivotal trial, investors may be disappoionted that a partnership wasn't announced and take the stock down. You can never tell for sure.