Madrigal licenses Arrowhead’s ARO-PNPLA3 in MASH deal

Arrowhead Pharmaceuticals has licensed its clinical-stage MASH program ARO-PNPLA3 to Madrigal Pharmaceuticals in a deal worth up to about $1 billion, giving Madrigal exclusive worldwide rights to develop, manufacture, and commercialize the RNA interference therapy. The companies announced the agreement on May 5, 2026. ARO-PNPLA3 is designed to silence PNPLA3 in the liver and is aimed at a genetically defined subgroup of patients with metabolic dysfunction-associated steatohepatitis, specifically those who are homozygous for the PNPLA3 I148M variant. Arrowhead said the program has shown liver fat reductions of up to 46% after a single dose in Phase 1 testing, while Madrigal framed the asset as a complement to its already marketed MASH drug, Rezdiffra. (arrowheadpharma.com)

Why it matters: For veterinary professionals, this is mainly a signal about where hepatology drug development is heading: more precision medicine, more RNA-based platforms, and more combination-focused pipeline building around chronic liver disease. Madrigal is using revenue from Rezdiffra, which posted $311.3 million in first-quarter 2026 net sales, to expand into genetically targeted programs, and it says the PNPLA3 mutation may account for roughly 30% of patients with moderate to advanced fibrosis, with higher prevalence in Hispanic populations. Even though this is a human medicine deal, it reflects the broader translational trend toward genotype-informed liver therapeutics that veterinary teams may increasingly see echoed in companion animal research and specialty care discussions. (ir.madrigalpharma.com)

What to watch: Next up will be Madrigal’s development plan for Phase 2, including how it positions ARO-PNPLA3 alongside Rezdiffra and other potential combination approaches in MASH. (ir.madrigalpharma.com)