Halozyme Therapeutics, Inc. (HALO.US) is set to engage in a patent battle with Merck & Co., Inc. (MRK.US) over the injectable version of Keytruda.

According to reports, a new patent dispute is brewing between Halozyme Therapeutics, Inc. (HALO.US) and Merck & Co., Inc. (MRK.US), with the focus of the controversy being the injectable version of the blockbuster cancer drug Keytruda. Sources revealed that Halozyme Therapeutics, Inc. believes that Merck & Co., Inc. has infringed on its patent and should sign a licensing agreement in order to sell the injectable Keytruda. Merck & Co., Inc.'s injectable version is based on an enzyme developed by the South Korean company Alteogen, which is the company's solution to the impending patent cliff of the intravenous Keytruda. Keytruda contributes nearly half of Merck & Co., Inc.'s total revenue. The intravenous version of Keytruda will lose its market exclusivity in the United States in 2028, when cheaper anti-PD-1 biosimilars will become available. Merck & Co., Inc. stated last year that its injectable version of Keytruda met its primary endpoints in key Phase 3 trials. The company also initiated a regulatory process last year to request the U.S. Patent Office to reconsider the granting of certain Mdase enzyme patents to Halozyme Therapeutics, Inc. because of the overly broad nature of these patents. Reportedly, Halozyme Therapeutics, Inc. will discuss the patent issue of the injectable Keytruda at an investor event on Wednesday. At the time of writing, Merck & Co., Inc. was down 0.54% in pre-market trading, while Halozyme Therapeutics, Inc. was up 0.81%.