** Mural Oncology's shares MURA.O slump 39.7% to $2.31 premarket

** MURA says it is stopping late-stage trials testing its experimental drug, nemvaleukin, with Merck's MRK.N Keytruda, to treat ovarian cancer

** Says trial unlikely to meet main goal as interim analysis shows no significant improvement in overall survival in patients given the combination (10.1 months) vs just chemotherapy (9.8 months)

** Co says to focus on another trial for the treatment of mucosal melanoma, a rare type of cancer that starts in mucous producing areas of the body

** As of last close, MURA stock down 11.3% in the past 12 months

(Reporting by Padmanabhan Ananthan)

((Padmanabhan.Ananthan@thomsonreuters.com;))