Macrocyclic Peptide Startup Unnatural Products Raises $45M Series B After $3.5B in Pharma Deals
Santa Cruz-based biotech Unnatural Products, led by CEO and co-founder Cameron Pye, has secured $45 million in Series B financing led by The Venture Collective to expand its platform for engineering synthetic macrocyclic peptide therapeutics and to advance its internal pipeline.
In 2023, the company raised $32 million in Series A funding led by Merck Global Health Innovation Fund and Artis Ventures to advance its macrocyclic peptide platform and expand beyond its initial oncology programs. Currently, Unnatural Products is developing internal therapeutic programs across cardiometabolic, inflammatory, and immunological diseases.
The series B funding comes shortly after the company signed a licensing agreement with Novartis targeting cardiovascular disease programs, a deal that reportedly includes $100 million upfront and up to $1.7 billion in milestone payments.
Across its disclosed partnerships with Novartis, argenx, and Merck, UNP has accumulated over $3.5 billion in potential milestone payments with roughly $83 million in equity raised since its 2019 seed round.
Drugging the Undruggable
Unnatural Products focuses on macrocyclic peptides, a class of molecules that sit between traditional small-molecule drugs and larger biologic therapies such as antibodies. These ring-shaped peptides can often bind protein surfaces with high specificity similar to biologics, while still retaining some properties associated with small molecules, such as potential cell permeability and oral dosing.
This combination has drawn attention as a way to address so-called “undruggable” targets—proteins involved in disease that have historically been difficult to modulate using conventional drug formats. Many of these targets participate in intracellular signaling pathways or protein-protein interactions that are challenging for standard small molecules to disrupt.
Alongside macrocyclic peptides, RNA medicines, bispecific antibodies, ADCs, cell therapies, gene therapies, and targeted protein degraders are all pushing into disease biology that older drug formats often struggled to reach.
For a wider look at where this is heading, we unpack it in our recent deep dive on the broader wave of new drug modalities now reshaping biopharma. The piece also looks at how the field is starting to mature, with large pharma companies putting real money and development muscle behind these platforms through acquisitions, licensing deals, and pipeline bets.
About the platform
The company was founded by Pye and Joshua Schwochert during their time as graduate students at the University of California, Santa Cruz, building on research from the lab of Scott Lokey, a pioneer in cyclic peptide research.
Unnatural Products has developed a drug discovery platform designed to engineer synthetic macrocyclic peptides in a repeatable, scalable way. Macrocycles typically require specialized design and synthesis strategies due to their constrained structures and unusual pharmacological properties.
Image credit: Unnatural Products
The system links computational design with automated laboratory experiments in a continuous optimization loop, where candidate molecules are repeatedly designed, synthesized, and tested. With each cycle, the platform aims to improve key drug properties such as potency, target selectivity, and cell permeability, helping researchers generate macrocyclic compounds that behave more like conventional drug molecules.
Aside from the recent Novartis deal, Unnatural Products also lists collaborations with several other pharmaceutical and biotechnology companies, including Merck, BridgeBio, and argenx, aimed at applying its macrocycle platform across different therapeutic areas. Merck itself has an oral macrocyclic peptide targeting PCSK9, now in phase 3 for reducing LDL cholesterol.
Topic: Biotech Ventures
