Xencor, Inc.

Xencor, Inc. (often referred to as Xencor) is a clinical-stage biopharmaceutical company founded in 1997. It is headquartered in Monrovia, California, with some sources also indicating Pasadena, California. Xencor is a publicly traded company on the NASDAQ stock exchange under the ticker symbol XNCR, with a market capitalization of approximately $1.11 billion as of July 2, 2026. The company had approximately 260-294 employees as of 2025-2026. For the trailing 12 months, Xencor reported revenues of $97.4 million, with FY2024 revenue at $125.6 million.

Xencor focuses on the discovery and development of engineered antibodies and cytokine therapies for the treatment of cancer and autoimmune diseases. Its core offering is the proprietary XmAb® protein engineering platform, which enables subtle modifications to an antibody's Fc domain to enhance properties such as effector function, half-life, and the creation of stable bispecific and multispecific antibody formats. Xencor operates as both a platform company, licensing its XmAb technology to partners, and a pipeline company, advancing its own clinical-stage drug candidates such as XmAb819 for renal cell carcinoma and Plamotamab for rheumatoid arthritis. The company holds more than 1500 patents worldwide related to its Fc domain technology.

Xencor exhibits an active two-way patent litigation posture, as indicated by its equal number of plaintiff and defendant cases. The company is involved in a direct dispute with Merus N.V., appearing as a defendant in a Delaware District Court case and as a plaintiff in a Patent Trial and Appeal Board (PTAB) proceeding.

The notable litigation involves Merus N.V. suing Xencor, Inc. in the Delaware District Court (Merus N.V. v. Xencor, Inc.), alleging infringement of patents related to methods of making antibodies, including multispecific antibodies. Xencor successfully moved to dismiss this suit, arguing that its research and development activities were protected by the Hatch-Waxman safe harbor (35 U.S.C. § 271(e)(1)), which covers activities reasonably related to the development and submission of information to the FDA. Concurrently, Xencor, Inc. initiated an Inter Partes Review (IPR) against Merus N.V. at the PTAB, challenging the patentability of Merus's U.S. Patent No. 9,358,286.