Oral activin type 2 A/B receptor antagonist (Unnatural Products)

With a successful dealmaking streak, Unnatural Products collected validation for its macrocyclic peptide discovery platform — and now it's collected the cash necessary to push its home-grown assets into the clinic. The biotech on Monday raised a $45-million series B, led by The Venture Collective, to advance its pipeline of macrocyclic peptides that are designed to address so-called "undruggable" targets. "The financing reflects the strong progress we’ve made in advancing our macrocyclic peptide platform and generating a pipeline of programmes with compelling biological rationale," Unnatural Products CEO Cameron Pye told FirstWord. "As our programmes matured and we began preparing for IND-enabling studies, this was the right moment to secure the capital needed to move multiple assets toward the clinic."The firm is moving several metabolic disease programmes into IND-enabling studies, including an oral activin type 2 A/B receptor antagonist in development for obesity. It's also pursuing other undisclosed "high-value" indications where there is significant unmet need, but a biologically validated target. "Our focus is on targets that have historically been difficult to drug with conventional small molecules or biologics, where we believe our orally delivered macrocyclic peptides can unlock new therapeutic opportunities," Pye added.Other investors in the round include argenx — one of Unnatural Products' development partners — and Droia Ventures, as well as existing investors Merck Global Health Innovation Fund, Artis Ventures and First Spark Ventures.Deals stack upUnnatural Products teamed up with argenx in July 2025 to use its platform, which combines AI-guided compound design, massively parallel synthesis and direct-to-biology screening, to discover macrocyclic peptides that bind targets selected by argenx with antibody-like specificity.  The company could receive up to $1.5 billion across option payments and research, development, regulatory and commercial milestones, plus tiered royalties. The feather in Unnatural Products' deal cap, however, came last month. Novartis agreed to pay the biotech up to $100 million upfront in a cardiovascular collaboration, as well as up to $1.7 billion in total potential milestones.The company's prior partnerships include one with BridgeBio Pharma centred on rare fibrotic diseases and possible oncology applications, and another with Merck & Co. focused on oncology, valued at about $220 million in milestones. The latter deal came shortly after Merck Global Health Innovation Fund led Unnatural Products' $32-million series A in 2023.