Madrigal Pharmaceuticals, Inc. has entered into an exclusive global licensing agreement with Arrowhead Pharmaceuticals to develop and commercialize ARO-PNPLA3, a clinical-stage RNA-based therapy targeting a key genetic driver of metabolic dysfunction-associated steatohepatitis (MASH). The move marks a significant step in expanding Madrigal’s pipeline with a precision medicine approach aimed at high-risk patient populations.
ARO-PNPLA3 is a small interfering RNA (siRNA) therapeutic designed to silence the PNPLA3 gene, specifically the I148M variant, which has been strongly linked to MASH progression. This genetic mutation is associated with increased liver fat accumulation, inflammation, fibrosis, cirrhosis, and a higher risk of hepatocellular carcinoma. Notably, around 30% of MASH patients with moderate to advanced fibrosis carry two copies of this variant, with particularly high prevalence among Hispanic populations.
Madrigal’s leadership emphasized the importance of targeting genetic drivers of disease in a condition as complex and heterogeneous as MASH. CEO Bill Sibold stated that integrating an siRNA-based therapy into the company’s portfolio reflects a long-term strategy to personalize treatment and improve patient outcomes. He also highlighted the potential impact on underserved communities, particularly Hispanic patients who are disproportionately affected by the disease.
Chief Medical Officer David Soergel added that the therapy complements Madrigal’s existing drug, Rezdiffra, and aligns with the company’s focus on validated disease mechanisms. He noted that early-stage clinical data support further development and that combination studies are being planned.
Findings from Phase 1 trials provide encouraging evidence for ARO-PNPLA3’s potential. In a U.S.-based study involving 55 patients with metabolic dysfunction-associated fatty liver disease, a single high dose reduced liver fat by up to 46% within 12 weeks in patients with the homozygous PNPLA3 variant. The effect appeared as early as six weeks and was sustained for at least 24 weeks. Importantly, no significant safety concerns were reported. However, no meaningful reduction in liver fat was observed among heterozygous participants. A smaller study conducted in Japan further supported these findings.
The therapy uses GalNAc-conjugated siRNA technology to deliver gene-silencing molecules directly to liver cells, offering a targeted way to address underlying disease mechanisms. Madrigal plans to consult with the U.S. Food and Drug Administration on the design of a Phase 2 trial combining ARO-PNPLA3 with Rezdiffra.
Under the terms of the agreement, Arrowhead will receive an upfront payment of $25 million and could earn up to $975 million in milestone payments, along with royalties on future sales.
This partnership underscores a growing industry shift toward genetically targeted therapies and positions Madrigal at the forefront of innovation in MASH treatment.