Sarepta rises on genetic therapy progress

** Shares of Sarepta Therapeutics SRPT.O rise 3% to $21 premarket

** Experimental genetic medicine SRP-1003 with Arrowhead Pharmaceuticals ARWR.O advances in early-mid-stage study - SRPT

** Trial milestone completion triggers $100 mln payment to ARWR; SRPT sells $174 mln of ARWR common stock for cash

** SRP-1003 targets muscle-weakening disorders myotonic dystrophy, facioscapulohumeral muscular dystrophy

** SRPT expects early data from study in H2 this year

** Separately, EVP and chief technical operations officer Bilal Arif to exit on Sept 16 amid restructuring

** YTD, up to last close, stock down nearly 83% vs 7.75% rise on Nasdaq Biotech Index .NBI