** Shares of Radiopharm Theranostics RAD.AX rise 12.5% to A$0.027, their biggest intraday pct gain since June 2
** The radiotherapeutics co receives U.S. Food and Drug Administration's (FDA) Fast Track Designation for its RAD101 product used in treatment of brain metastases
** FDA's Fast Track Designation grants help in expediting the process of product review
** Stock marks its highest level in a week
** About 2.5 mln shares change hands, 1x the 30-day average
** Stock up 8.3% YTD, including moves in current session
(Reporting by Jasmeen Ara Shaikh in Bengaluru)
((JasmeenAraIslam.Shaikh@thomsonreuters.com;))