Xencor Announces Extension of U.S. Patent Term on Certain Xtend™ Antibodies

Key Terms

fc domain medical

The Fc domain is the tail end of an antibody molecule that acts like a handle for the immune system, determining how the antibody is cleared from the body and whether it activates immune responses. For investors, changes or engineering of the Fc domain can alter a therapy’s dosing frequency, safety profile and commercial value — similar to redesigning a car’s fuel tank or brakes to improve range and safety.

half-life medical

Half-life is the time it takes for a quantity (such as a drug in the body, a radioactive substance, or a decaying revenue stream) to decrease to half its original amount. Think of it like the time it takes for a hot cup of coffee to cool to half its initial warmth: it tells you how quickly the effect fades. For investors, half-life helps estimate how long a product’s impact, a payment stream, or a risk factor will meaningfully influence a company’s performance.

defined benefit pension plans financial

A defined benefit pension plan is a retirement program that guarantees employees a specific monthly payment after they retire, usually based on salary and years of service, with the employer responsible for funding and managing the investments. It matters to investors because these plans create long-term legal and financial obligations for a company — if investments underperform or life expectancies rise, the company may need to use cash, cut dividends, or take on debt to fill the gap, much like a homeowner must pay a fixed mortgage regardless of income swings.

-- Royalty term on Ultomiris® sales in the United States anticipated to continue into year-end 2028, extending term by three years --

-- Additional $100 million to $120 million in potential royalty revenue estimated to be received by Xencor, based on consensus sales forecasts --

PASADENA, Calif.--(BUSINESS WIRE)-- Xencor, Inc. (NASDAQ:XNCR), a clinical-stage biopharmaceutical company developing engineered antibodies for the treatment of cancer and autoimmune diseases, today announced the issuance of U.S. Patent 12,492,253, which covers Xencor’s Xtend™ Fc domain for extending the half-life of antibodies targeting C5, with a term that extends into December 2028. The new patent term is approximately three years longer than the previous latest-to-expire U.S. patent covering the Xtend Fc domain.

Xencor now anticipates receiving low-single digit royalties on net sales of Ultomiris® (ravulizumab-cwvz), an anti-C5 antibody engineered with a licensed Xtend Fc domain, into December 2028 in the United States. Ultomiris is a drug being developed and commercialized by Alexion Pharmaceuticals, Inc., and is a registered trademark of Alexion. Xencor has also previously secured regulatory extensions of exclusivity in several EU countries, Japan and Australia.

“Xencor’s Xtend antibody half-life extension technology is one of several modular XmAb Fc domains that power Xencor’s XmAb medicines and drug candidates across internal and partner portfolios,” said Bassil Dahiyat, Ph.D., president and chief executive officer at Xencor. “Importantly, this patent term extension also extends the U.S. royalty term for Ultomiris by approximately three years. We anticipate the resulting additional revenue will support our internal pipeline as it advances into later stages of clinical development and will drive further innovation across our portfolio, continuing to fuel the cycle of value creation that has been central to our strategy.”

In 2023, OMERS, one of Canada’s largest defined benefit pension plans, acquired royalties due to Xencor on global Ultomiris sales subject to annual caps beginning in 2026. For potential sales related to Ultomiris occurring between 2026 and 2028, OMERS is entitled to receive up to $35 million annually with excess reverting to Xencor. For the nine-month period ending September 30, 2025, Xencor recognized non-cash royalty revenue of $51.0 million. Based upon consensus sales forecasts of Ultomiris, Xencor estimates recognizing potential royalty revenue in excess of the caps in the range of $100 million to $120 million in aggregate for the extended patent term through 2028.

About Xencor

Xencor is a clinical-stage biopharmaceutical company developing engineered antibodies for the treatment of patients with cancer and autoimmune diseases. More than 20 candidates engineered with Xencor's XmAb® technology are in clinical development, and multiple XmAb medicines are marketed by partners. Xencor's XmAb engineering technology enables small changes to a protein’s structure that result in new mechanisms of therapeutic action. For more information, please visit www.xencor.com.

Forward-Looking Statements

Certain statements contained in this press release may constitute forward-looking statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include statements that are not purely statements of historical fact, and can generally be identified by the use of words such as “potential,” “can,” “will,” “plan,” “may,” “could,” “would,” “expect,” “anticipate,” “seek,” “look forward,” “believe,” “committed,” “investigational,” “indicates,” “supports,” and similar terms, or by express or implied discussions relating to Xencor’s business, including, but not limited to, statements regarding expectations for future royalty revenues, the quotations from Xencor's president and chief executive officer, and other statements that are not purely statements of historical fact. Such statements are made on the basis of the current beliefs, expectations, and assumptions of the management of Xencor and are subject to significant known and unknown risks, uncertainties and other factors that may cause actual results, performance or achievements and the timing of events to be materially different from those implied by such statements, and therefore these statements should not be read as guarantees of future performance or results. Such risks include, without limitation, the risks associated with the process of discovering, developing, manufacturing and commercializing drugs that are safe and effective for use as human therapeutics, the ability of publicly disclosed preliminary clinical trial data to support continued clinical development and regulatory approval for specific treatments, the risk of loss of key members of management, the risk that the fair value of our marketable equity securities will decline and the risks, uncertainties and other factors described under the heading “Risk Factors” in Xencor's annual report on Form 10-K for the year ended December 31, 2024 as well as Xencor's subsequent filings with the Securities and Exchange Commission. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. Xencor undertakes no obligation to revise or update these forward-looking statements to reflect events or circumstances after the date hereof, except as required by law.

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Charles Liles

cliles@xencor.com

(626) 737-8118

For media:

Cassidy McClain

Inizio Evoke

cassidy.mcclain@inizioevoke.com

(619) 694-6291

Source: Xencor, Inc.