** Australian shares of Mesoblast MSB.AX rise as much as 4.2% to A$2.24, their biggest intraday pct gain since April 22
** Stock among the top gainers in Australia's S&P/ASX 200 index .AXJO, which is down 0.3%
** Stock set for a second consecutive session of gains, if current trend holds
** The drugmaker says its lower back-treating drug, rexlemestrocel-L, has achieved patient recruitment target
** The patent protects the drug from competition, supports higher long‑term revenues
** Despite moves, MSB down 17.8% YTD
(Reporting by Aamir Sheik Khalid in Bengaluru)
((Aamir.SheikKhalid@thomsonreuters.com))