argenx agrees Unnatural takeover deal worth up to $1.15bn

Unnatural Products' development platform for orally delivered macrocyclic peptide drugs has captured the attention of argenx, which tapped into it via a licensing deal signed last year and has now decided it wants full ownership.

The takeover deal – worth up to $1.15 billion including $550 million in upfront cash – will upgrade the Dutch biotech's minority stake in Unnatural Products (UNP) and will combine the start-up's peptide expertise with argenx's antibody engineering capabilities.

The agreement comes just a few months after argenx completed its $2.2 billion acquisition of Forte Biosciences, which added a late-stage candidate for coeliac disease.

It further diversifies the company's pipeline beyond FcRn inhibitor Vyvgart/Vyvgart Hytrulo (efgartigimod) for generalised myasthenia gravis (gMG) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), two chronic autoimmune disorders that affect the nervous system and muscle function.

argenx's efforts to extend the label for Vyvgart/Vyvgart Hytrulo into new indications have suffered late-stage blows, including a failed trial in Sjögren's disease and a demand from the FDA for another clinical trial in dermatomyositis.

UNP has said its platform lends itself to developing compounds active against targets historically considered 'undruggable', and – along with argenx – it has previously signed partnerships with MSD, Novartis, and BridgeBio.

"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, the Amsterdam-based biotech's chief executive.

"UNP adds macrocyclic peptide capabilities that are highly complementary to our antibody engineering and creates new possibilities for oral and long-acting medicines," she added.

UNP will continue operating from its base in Santa Cruz, California, with its current team, in order to "preserve the science-first culture behind its success," said argenx in a statement. The acquisition is expected to close by the end of the year, subject to customary closing conditions.

In July 2025, argenx and UNP signed a multi-target research collaboration and option-to-license agreement valued at up to $1.5 billion, aimed mainly at developing shelf-stable, once-daily oral pills capable of mimicking the precision of injectable antibodies, including an FcRn inhibitor.