Merus BV

Merus N.V. (often referred to interchangeably with its earlier legal form, Merus B.V.) is a clinical-stage biotechnology company that specializes in developing innovative multispecific antibody therapeutics for cancer treatment. Founded in 2003 and headquartered in Utrecht, the Netherlands, with a U.S. office in Cambridge, Massachusetts, the company was formerly publicly traded on Nasdaq under the ticker MRUS. In December 2025, Merus N.V. was acquired by Genmab A/S for approximately $8.0 billion, making it a subsidiary of Genmab Holding II B.V. Prior to its acquisition, Merus N.V. employed approximately 260-321 people and reported annual revenues of around $36.1 million in 2024, primarily from collaboration agreements.

Merus focuses on developing full-length human bispecific and trispecific antibodies, branded as Biclonics® and Triclonics® respectively, utilizing its proprietary Multiclonics® platform. Its pipeline includes drug candidates like petosemtamab (MCLA-158) for head and neck squamous cell carcinoma, MCLA-129 for non-small cell lung cancer and solid tumors, and Zenocutuzumab (Zeno) for NRG1 fusion cancers. These therapies are designed to bind multiple targets simultaneously, aiming to overcome tumor resistance and enhance treatment efficacy.

The company actively engages in patent litigation to protect its intellectual property. Merus is tracked in two patent cases: one as a plaintiff and one as a defendant. The plaintiff case, "Merus BV v. Unknown Defendant" in the Delaware District Court, aligns with Merus N.V.'s patent infringement suit against Xencor, Inc., concerning technologies for generating antibodies through transgenic mammals (such as the Merus Mouse) and multispecific antibodies. Merus's appearance as a defendant in "Unified Patents v. Merus BV" at the Patent Trial and Appeal Board (PTAB) indicates challenges to its asserted patents, with Xencor identified as a petitioner in similar PTAB cases against Merus in 2025. This posture characterizes Merus as an operating company that both defends against and asserts its significant patent portfolio in the biotechnology space.

Notable context for Merus includes its substantial acquisition by Genmab A/S, which concluded in December 2025, integrating Merus's innovative antibody platforms and pipeline, particularly petosemtamab, into Genmab's portfolio. The company has also been involved in past patent disputes with other pharmaceutical entities, such as Regeneron Pharmaceuticals, Inc., regarding antibody production technologies.