argenx announced it will acquire Unnatural Products in a transaction valued at about $1.15 billion. The immunology firm already holds a minority stake and will purchase the remaining shares. The agreement is slated to close by the end of the calendar year.
Under the agreement, the acquirer will pay $550 million in cash up front. An additional $595 million is tied to development and regulatory milestones that Unnatural Products must achieve after the deal is finalized. Together, the two tranches could reach the full purchase price, providing a financial framework that rewards progress on the pipeline.
The purchase adds a macrocyclic peptide discovery engine to the deal’s immunology portfolio. This engine broadens the ability to develop oral or long-acting medicines for serious immune-mediated diseases, expanding the therapeutic options beyond traditional antibodies. The biotech’s platform targets high-value, traditionally hard-to-drug proteins, offering a route to address targets that have been considered undruggable by conventional approaches.
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“UNP adds macrocyclic peptide capabilities that are highly complementary to our antibody engineering and creates new possibilities for oral and long-acting medicines,” said CEO Karen Massey. She noted that the two teams share a science-first, entrepreneurial approach focused on patients, and that the combined expertise is expected to accelerate discovery and development timelines.
After closing, the biotech will keep its Santa Cruz, California site. The site will become the group’s hub for peptide discovery, with the existing team leading research under a strategic framework agreed upon with argenx. The acquirer will contribute clinical development and commercialization expertise.
He explained that the partnership provides an ideal environment to accelerate and amplify the vision of delivering innovative therapies to patients.
