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Pairs Unnatural Products’ (UNP) peptide expertise with argenx's antibody engineering, expanding the ways to target novel biology
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Extends argenx’s immunology innovation to more patients, with the potential for oral and long-acting medicines
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Builds on more than two years of collaboration and investment; UNP to continue operating from Santa Cruz, California with its current team, preserving the science-first culture behind its success
Amsterdam, the Netherlands, November 9, 2026, 07:00 CET – argenx (Euronext & Nasdaq: ARGX), the immunology innovation company, today announced a definitive agreement to acquire Unnatural Products, Inc. (UNP), adding a macrocyclic peptide discovery engine to its immunology innovation capabilities. argenx, which already holds a minority stake in UNP, will acquire all remaining shares in a transaction valuing UNP at up to approximately $1.15 billion across upfront and milestone payments. This acquisition expands the ways argenx can pursue novel biology and develop oral or long-acting medicines for people living with serious immune-mediated diseases.
“Our ambition is to be the leading immunology innovation company, and as argenx builds its next chapter, we are investing with discipline where it will count the most for patients,” said Karen Massey, Chief Executive Officer of argenx. “UNP adds macrocyclic peptide capabilities that are highly complementary to our antibody engineering and creates new possibilities for oral and long-acting medicines. After working together for more than two years, we also know there is a strong fit in how we work: science first, entrepreneurial and focused on patients. We want to preserve what has made UNP successful while bringing the strengths of both teams together.”
“Today is a tremendous milestone for UNP and a testament to the exceptional work of our scientists, employees, collaborators and supporters,” said Cameron Pye, Ph.D., CEO and Co-Founder of UNP. “From the earliest days, we believed our platform had the potential to redefine what is possible in the discovery and design of new medicines. I am so proud of what our team has accomplished and believe argenx provides the ideal environment to accelerate and amplify that vision to bring innovative therapies to patients.”
Following closing of the acquisition, UNP’s team and leadership will continue to operate from its Santa Cruz, California site, which will serve as argenx’s home for peptide discovery. UNP will continue to lead its discovery work, within a strategic framework agreed upon with argenx. argenx will bring its clinical development and commercialization capabilities to advance those medicines to patients.
Transaction Terms
Under the terms of the agreement, argenx will acquire UNP for an upfront payment of $550 million in cash on hand and up to $595 million in payments contingent on achievement of specified development and regulatory milestones, for total potential consideration of up to approximately $1.15 billion.
The boards of directors of both companies have approved the transaction. The acquisition is expected to close by the end of the year, subject to customary closing conditions.
Advisors
Morgan Stanley & Co. LLC is serving as exclusive financial advisor and DLA Piper LLP is serving as legal advisor to argenx. Latham & Watkins LLP is serving as legal counsel to UNP.
About argenx
argenx is the immunology innovation company, focused on turning immunology breakthroughs into medicines for patients. The company seeks novel biology wherever it emerges, co-creating with academic researchers through its Immunology Innovation Program (IIP) and investing in promising science, to develop treatments for people living with underserved diseases. By advancing molecules with the potential to reach multiple diseases and patient populations, argenx is building a world-class portfolio. This approach produced the first approved antibody fragment targeting the neonatal Fc receptor (FcRn) and today powers a growing pipeline of early- and late-stage programs across several therapeutic areas.
About Unnatural Products, Inc.
Unnatural Products, Inc. (UNP), a Santa Cruz, California-based biotech company, has developed a platform that addresses the complexities of medicinal chemistry in the macrocyclic peptide space through a combination of parallel experimentation and machine learning. Founded by macrocycle pioneers whose academic work uncovered how nature’s macrocycles work, UNP is developing a portfolio of therapeutic macrocycles against high-value and traditionally difficult-to-drug targets.