** Shares of drug developer Dianthus Therapeutics DNTH.O rise 17% to $31 premarket

** DNTH's experimental drug claseprubart improved symptoms in adults with generalized myasthenia gravis in a mid-stage trial, company says

** The 13-week trial enrolled 65 patients, and patients received shots under the skin every two weeks at either 300 mg, 600 mg, or a placebo

** Both doses of the drug led to statistically significant improvements in daily function and muscle strength, starting as early as the first week and sustained through week 13

** Dianthus plans to meet U.S. regulators after this Phase 2 study and aims to start a late-stage trial in 2026

** As of last close, DNTH stock up 21.6% YTD

(Reporting by Padmanabhan Ananthan)

((Padmanabhan.Ananthan@thomsonreuters.com))