Adds Halozyme's response in paragraph 4 and Merck's response in paragraph 8, background in paragraphs 3,5-7

March 5 (Reuters) - Merck's MRK.N injected version of its blockbuster cancer drug Keytruda could face a potential patent challenge from biotech Halozyme Therapeutics HALO.O, the Wall Street Journal reported on Wednesday, citing people familiar with the matter.

According to Halozyme, the new version of Keytruda infringes on its patents, the report said.

A possible patent dispute could be a setback for Merck, which is hoping that a simpler-to-use version of the drug could help drive growth even after key patents on its original intravenous version expire later in the decade.

Halozyme, in a statement, said "it is our preference to sign a license agreement with any company using our intellectual property to deliver drugs", but it did not comment on potential litigation.

The injected version of Keytruda is still in clinical testing and expected to be launched by early 2026.

Merck has partnered with South Korea-based biopharmaceutical company Alteogen 196170.KQ to use a variant of the hyaluronidase family of enzymes, which allows large volume of subcutaneous, or under the skin, administration of drugs through the injected version.

Alteogen's rival Halozyme also utilizes hyaluronidase enzymes to develop injectable versions of various drugs, which include treatments from Roche ROG.S, Johnson & Johnson JNJ.N and Pfizer PFE.N, among others.

"We strongly believe that any Halozyme patents that attempt to cover this variant are invalid," Merck told Reuters, adding that the drugmaker has filed invalidity petitions with the U.S. patent office on it.

In November, Merck's injectable version of Keytruda was shown to be on a par with the IV version, which had sales of $29.5 billion in 2024.

(Reporting by Christy Santhosh in Bengaluru; Editing by Shilpi Majumdar)

((Christy.Santhosh@thomsonreuters.com;))