** Drug developer GH Research's GHRS.O shares rise 5.8% to $9.5 premarket

** Co says its lead experimental drug met the main goal in two mid-stage studies testing it as a treatment for postpartum depression and bipolar II disorder

** The drug, GH001, helped significantly reduce severity of depressive episodes and led to rapid antidepressant effect in the studies - GHRS

** In both trials, GH001 was well tolerated with no reported treatment-related serious side-effects - GHRS

** Bipolar II disorder is a mental health condition that causes extreme mood swings with at least one major depressive episode and at least one hypomanic episode

** Up to last close, stock up 54.3% over the past 12 months

(Reporting by Mariam Sunny in Bengaluru)

((Mariam.ESunny@thomsonreuters.com;))