** Shares of therapy developer Marinus Pharmaceuticals

fall ~61.5% to 65 cents premarket

** Co says it is discontinuing development of its oral drug ganaxolone after it missed the main goal in a late-stage trial in patients with a rare genetic brain disease called tuberous sclerosis complex (TSC)

** MRNS says the drug did not show a significant reduction in frequency of TSC-associated seizures

** Co says it is exploring strategic alternatives and is taking additional steps to reduce costs, including a reduction in its workforce

** Up to last close, stock down 84.5% YTD

(Reporting by Christy Santhosh)

((Christy.Santhosh@thomsonreuters.com))