March 5 (Reuters) - Biotech Halozyme Therapeutics

believes the new version of Merck's ( MRK ) blockbuster

cancer drug Keytruda infringes on its patents, the Wall Street

Journal reported on Wednesday, citing people familiar with the

matter.

According to Halozyme, Merck ( MRK ) must sign a licensing agreement

in order to sell its new version, the report said.

Merck ( MRK ) is developing an injectable version of Keytruda, which

could protect it from competition when the intravenous version

loses exclusivity later in the decade.

Merck ( MRK ) and Halozyme did not immediately respond to a Reuters

request for comment.