** Shares of Mesoblast rise as much as 46% to A$2.890, their highest since Dec. 16, 2020

** Stock posts its biggest intraday percentage rise since April 2

** Drug developer says U.S. Food and Drug Administration approved co's cell therapy for graft-versus-host disease

** About 28.1 mln shares change hands, compared with the 30-day average volume of around 6.3 mln

** Stock up over 825% YTD, including session's move

(Reporting by Aaditya Govind Rao in Bengaluru)

((Aaditya.govindrao@thomsonreuters.com;))