Lundbeck said in a statement that the Phase III data demonstrated the efficacy of the drug candidate, Lu AA21004, compared with a placebo in the treatment of major depression.

"Lundbeck's current share price reflects deep investor skepticism on the chances of success and we could see significant share price movement on this news," Deutsche bank said in a research note.

Shares in Lundbeck spiked 8.8 percent to 118.60 crowns at 1405 GMT after the announcement, against a 1.7 percent drop in the Copenhagen stock exchange's benchmark index

Deutsche Bank said in the note the antidepressant could be worth up to 55 Danish crowns per Lundbeck share.

Lundbeck has warned earnings will stall until 2015 as its key anti-depressant Cipralex - sold as Lexapro in the United States and Japan - faces cheap generic competition and it invests in new product launches to secure future growth.

Lundbeck and Japanese partner Takeda Pharmaceutical Co will submit a new drug application for Lu AA21004 to the United states Food and Drug Administration (FDA) and a marketing authorization application to the European Medicines Agency (EMA) and Health Canada in the second half of 2012, it said in the statement.

"We are very pleased with the consistency of the efficacy and tolerability profile across the program that we have obtained so far," Lundbeck's head of research and development, Anders Gersel Pedersen, said in the statement.

(Reporting by Mette Fraende; Editing by Greg Mahlich)

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