Xencor secured a U.S. patent extension on December 9, 2025, extending U.S. Patent 12,492,253 for its Xtend Fc domain, a technology that lengthens the half‑life of therapeutic antibodies. The extension pushes the expiration of the royalty‑eligible period for Ultomiris sales in the United States to December 2028, adding roughly three years to the existing term.
The extension is expected to generate an additional $100 million to $120 million in royalty revenue over the extended period. That estimate is based on the current royalty structure, which caps OMERS’ share at $35 million per year for 2026‑2028 under the 2023 OMERS royalty sale. After the cap, any excess revenue flows back to Xencor, creating a predictable cash‑flow stream that can be earmarked for pipeline development.
Xencor’s Q3 2025 earnings report showed $21.0 million in revenue, up 18% from $17.8 million in Q3 2024, driven almost entirely by non‑cash royalty income. Net loss narrowed to $6.03 million from $46.29 million a year earlier, reflecting disciplined cost management and the growing contribution of royalty income. The company’s balance sheet remains strong, with $633.9 million in cash, cash equivalents, and marketable debt securities as of September 30, 2025.
The company’s T‑cell engager strategy has advanced to two first‑in‑class CD3 bispecific antibodies, positioning Xencor to capture a growing market for cell‑based therapies. The extended royalty stream provides the financial runway to accelerate these programs without immediate dilution. CEO Bassil Dahiyat noted that “the Xtend platform’s extended protection gives us a stable foundation to invest in our next‑generation bispecifics and other engineered antibody candidates.”
The OMERS royalty sale, completed in November 2023 for $215 million, granted OMERS the right to collect royalties on Ultomiris and Monjuvi, with annual caps of $35 million for 2026‑2028. Xencor retains any royalty revenue above those caps, a structure that now benefits from the extended patent term. The company’s management highlighted that the extension “strengthens our intellectual‑property moat and enhances the predictability of our revenue streams.”
Investors reacted positively to the extension, citing the added certainty of a multi‑year royalty stream and the strategic advantage it provides in a competitive antibody market. The market view reflects confidence that the extended patent will support Xencor’s pipeline and reinforce its balance sheet resilience.
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