Why it matters: The acquisition adds a new drug modality to argenx’s antibody-focused discovery capabilities, potentially enabling oral and longer-acting treatments for autoimmune diseases. It also marks another major acquisition this year, following the $2.2 billion purchase of Forte Biosciences.
By the numbers: Argenx will pay $550 million (€493 million) upfront in cash, with up to $595 million (€534 million) in additional payments tied to development and regulatory milestones.
- The transaction is expected to close by the end of 2026, subject to customary conditions.
- UNP’s leadership and team will remain in Santa Cruz, California, where the company will operate as argenx’s peptide discovery hub.
Backstory: The two companies are far from strangers. In July 2025, they announced a multi-target research collaboration worth up to $1.5 billion in potential milestone and option payments, plus royalties.
Under that agreement, UNP was responsible for discovering oral macrocyclic peptides against targets selected by argenx, which held options to develop and commercialize resulting drugs. Argenx also invested in UNP, becoming a minority shareholder before agreeing to acquire the remaining shares.
How it works: Macrocyclic peptides are ring-shaped molecules designed to combine some of the selectivity of antibodies with the drug-like properties of smaller molecules. Some can enter cells and reach targets that are difficult to address with conventional drugs, while their chemical structure can make oral administration possible.
UNP’s discovery platform combines AI-guided molecular design, large-scale parallel chemical synthesis and biological screening to identify and optimize these compounds.
The acquisition also builds on an existing research program. Argenx and UNP have been working together on an oral FcRn inhibitor, targeting the same receptor as argenx’s blockbuster Vyvgart. In a May 2026 earnings call, CEO Karen Massey identified FcRn as the first of several targets under their collaboration. An oral treatment could offer patients a more convenient alternative to Vyvgart’s injectable formulations.
A well-connected acquisition: UNP has attracted several other pharmaceutical partners beyond argenx:
- Novartis: In February 2026, the Swiss drugmaker signed an agreement worth up to $1.8 billion to develop macrocyclic peptide therapeutics for an undisclosed cardiovascular program.
- MSD: A 2024 collaboration, worth up to $220 million in potential milestones, focuses on a challenging oncology target.
- BridgeBio Pharma: The companies began collaborating in 2021 on rare diseases and oncology. In December 2024, BridgeBio exercised an option to license candidates discovered through UNP’s platform.
Neither acquisition announcement explains whether these existing partnerships will change under argenx’s ownership.
The bigger picture: Argenx is increasingly using acquisitions to expand beyond its successful Vyvgart (efgartigimod) franchise. In August, it completed the $2.2 billion acquisition of Forte Biosciences, gaining FB102, a CD122-targeting antibody being advanced toward Phase 3 development in celiac disease.
In a recent interview with European Biotechnology, Massey explained the company’s approach to external innovation, noting that “not everything has to come from argenx.”
That diversification comes amid mixed clinical progress. In October, argenx halted a Phase 3 trial of efgartigimod in Sjögren’s disease after an interim analysis indicated the study would not meet its primary endpoint.
A drop in the bucket: Argenx’s acquisitions are being supported by surging Vyvgart sales, which reached $1.72 billion in the third quarter of 2026, up 54% year over year. The company reported $3.7 billion in cash, cash equivalents and short-term financial assets at the end of September, even after spending approximately $2.1 billion to acquire Forte Biosciences. The $550 million upfront payment for Unnatural Products represents just 15% of its remaining liquidity.
What to watch: Unlike the Forte acquisition, which brought an already clinical-stage drug into argenx’s pipeline, the UNP deal is primarily an investment in discovery capabilities. The companies have not disclosed specific new programs or clinical timelines arising from the acquisition. The next test will be whether bringing UNP’s platform in-house can translate into differentiated immunology drug candidates.
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