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BERLIN, April 23 (Reuters) - Swiss biotech investor Xlife Sciences AG XLS.S said on Wednesday its portfolio company Veraxa Biotech AG would list on U.S. exchange Nasdaq in a $1.64 billion merger deal with a special-purpose acquisition vehicle, or SPAC.

The planned merger with the SPAC Voyager Acquisition VACH.O values Veraxa, cancer drug developer, at about $1.3 billion excluding trust funds, Xlife said in a statement.

Assuming a share price of $10 and full participation of the investors behind Voyager, the implied pro-forma equity value of the combined entity will be about $1.64 billion, it said.

Upon expected completion of the transaction in the fourth quarter, Veraxa stands to receive gross proceeds of up to $253 million in Voyager's trust account, Xlife said.

Veraxa, based in Switzerland, runs research and development facilities in Heidelberg, Germany, and it is already testing drug candidates on humans.

It focuses on antibody drug conjugates, which combine a tumour-seeking monoclonal antibody with a cell-killing chemical molecule, and on bispecific T cell engagers, which direct certain immune-system cells against cancer cells.

(Reporting by Ludwig Burger in Frankfurt, Bipasha Dey in Bengaluru and Miranda Murray in Berlin; Editing by Janane Venkatraman, Saad Sayeed and Tom Hogue)

((Bipasha.Dey@thomsonreuters.com;))