REGENXBIO Inc. (Nasdaq:RGNX) today announced that Dimension Therapeutics, Inc. (Nasdaq:DMTX) notified REGENXBIO that it has determined that it has received a “superior proposal” as defined in the merger agreement under which REGENXBIO would have acquired Dimension in an all-stock transaction for an implied value of approximately $3.41 per share based on the closing stock price of REGENXBIO stock on August 24, 2017.