Merck's injected version of its blockbuster cancer drug Keytruda could face a potential patent challenge from biotech Halozyme Therapeutics, the Wall Street Journal reported on Wednesday, citing people familiar with the matter.

Both Merck & Co. and Halozyme are holding their ground in a freshly unveiled patent dispute surrounding the New Jersey pharma’s under-the-skin version of its blockbuster cancer drug Keytruda.

The company has asked the U.S. patent office to reconsider patents that could prevent it from selling a new version of its drug Keytruda.

The new formulation of Keytruda, currently under FDA review, is sparking conflict with Halozyme, which makes enzymes that convert intravenous drugs into injectable versions.

Shares in pharmaceuticals giant Merck (MRK) weakened today on fears that a patent battle could jeopardize its plans to sell a new version of

Merck's newly developed injected version of its blockbuster cancer drug, Keytruda, may be at the center of a potential patent dispute, according to a report by The Wall Street Journal

A new patent dispute is brewing between Halozyme Therapeutics (NASDAQ:HALO), a biotech focused on drug delivery technology, and Merck (NYSE:MRK) over an injectable version of the New Jersey-based pharma giant’s cancer blockbuster,