$1.15B AI-Guided Macrocycle Discovery Lands at argenx

On November 9, 2026, argenx, a global immunology company, entered into a definitive agreement to acquire Unnatural Products (UNP), a developer of orally delivered macrocyclic peptides.¹ argenx will pay $550 million upfront plus contingent value rights tied to development and regulatory milestones, for a total potential value of up to approximately $1.15 billion. Closing is expected by year-end.

The deal builds on a multitarget research collaboration the companies have run for more than 2 years.¹ After closing, UNP’s team and platform will remain in Santa Cruz as argenx’s dedicated macrocyclic peptide discovery hub.

What Does a Macrocycle Platform Add to an Antibody-Focused Portfolio?

Macrocyclic peptides combine the precision and efficacy of biologics with the convenience of oral dosing and can reach intracellular targets long out of range for conventional drugs.¹ The company’s discovery platform pairs AI-guided design with massively parallel synthesis and direct-to-biology screening, which it says allows it to engineer drug-like macrocycles repeatedly and at scale.

“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, CEO, argenx, in a press release. “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 2 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.”

Why Does This Matter?

The transaction brings a chemically synthesized oral modality into a company built on engineered antibodies, a shift that carries a different set of CMC demands.¹ Turning a macrocycle into a viable oral dosage form still means contending with low intestinal permeability and gastrointestinal instability.² William Fang, vice president and head of oligonucleotide and peptide development, WuXi TIDES, WuXi AppTec, noted that oral peptide bioavailability stays modest even when molecular design and formulation are optimized together. “That is why every incremental gain from chemical design matters,” he said.²

Formulation adds analytical complexity as well. Brittany Hayes, PhD, of CordenPharma, explained³ “with the use of these permeation enhancers, there needs to be simultaneous dissolution of the permeation enhancer and the peptide. So, there may be some challenges here with analytical methods.”

How Have Recent Oral Peptide Approvals Set a Precedent for This Deal?

Two FDA approvals earlier this year offer regulatory and commercial reference points for the modality argenx is buying into.^4,5 In July, the FDA approved Merck’s Lipfendra (enlicitide), a macrocyclic peptide, as a once-daily 20-mg tablet to reduce low-density lipoprotein cholesterol in adults with hypercholesterolemia.⁴ It is the first oral inhibitor of proprotein convertase subtilisin/kexin type 9, a target previously addressed with monoclonal antibodies. The approval rested on 2 Phase 3 trials in which enlicitide reduced low-density lipoprotein cholesterol by a placebo-adjusted 56% and 59% at week 24.

In March, the FDA approved Johnson & Johnson’s Icotyde (icotrokinra), the first targeted oral peptide that blocks the IL-23 receptor, for moderate to severe plaque psoriasis based on 4 Phase 3 studies including 2500 patients.⁵ The product’s dosing instructions reflect the formulation constraints of the class: patients take one pill daily with water upon waking, 30 minutes before eating. Icotrokinra was also discovered through a partnership, a collaboration between Protagonist Therapeutics and Johnson & Johnson, mirroring the platform-partnering model UNP built before its acquisition.

References

1. Unnatural Products, Inc. Unnatural Products to be acquired by argenx for up to $1.15 billion to advance next-generation medicines. News release. GlobeNewswire. November 9, 2026. Accessed November 9, 2026. https://www.globenewswire.com/news-release/2026/11/09/3398043/0/en/unnatural-products-to-be-acquired-by-argenx-for-up-to-1-15-billion-to-advance-next-generation-medicines.html
2. Challener CA. Improving oral peptide delivery through structural modifications. Pharmaceutical Technology. November 2, 2026. Accessed November 9, 2026. https://www.pharmtech.com/view/improving-oral-peptide-delivery-through-structural-modifications
3. Haigney S. AAPS PharmSci 360: challenges in peptide-based drugs. Pharmaceutical Technology. Published November 12, 2024. Accessed November 9, 2026. https://www.pharmtech.com/view/aaps-pharmsci-360-challenges-in-peptide-based-drugs
4. Merck & Co., Inc. Merck’s LIPFENDRA (enlicitide) is the first and only once-daily oral PCSK9 inhibitor approved by the U.S. FDA to reduce LDL-C in adults with hypercholesterolemia. July 16, 2026. Accessed November 9, 2026. https://www.merck.com/news/mercks-lipfendra-enlicitide-is-the-first-and-only-once-daily-oral-pcsk9-inhibitor-approved-by-the-u-s-fda-to-reduce-ldl-c-in-adults-with-hypercholesterolemia/
5. Johnson & Johnson. FDA approval of ICOTYDE (icotrokinra) ushers in new era for first-line systemic treatment of plaque psoriasis with a targeted oral peptide. March 18, 2026. Accessed November 9, 2026. https://www.jnj.com/media-center/press-releases/fda-approval-of-icotyde-icotrokinra-ushers-in-new-era-for-first-line-systemic-treatment-of-plaque-psoriasis-with-a-targeted-oral-peptide