On Monday, Arrowhead Pharmaceuticals, Inc. ( ARWR ) released topline results from Part 2 of a Phase 1/2 study of ARO-C3, the company’s investigational RNA interference (RNAi) therapeutic designed to reduce liver production of complement component 3 (C3) as a potential therapy for various complement-mediated diseases.

ARO-C3 is designed to reduce hepatocyte production of complement C3 as a potential treatment for various complement-mediated renal diseases. 

The dysregulated activity of the complement system can contribute to tissue injury and the progression of the disease. By silencing C3, investigational ARO-C3 has the potential to treat complement-mediated renal diseases by modulating the activation of the complement cascade.

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The company plans to present additional results at a medical meeting in 2025.

Select Phase 1/2 Study Results

Pharmacodynamic effects: Maximum mean reduction in C3 of 89% and mean sustained reduction of greater than 87% from baseline through week 24.

Maximum mean reduction in serum AH50 (alternative pathway hemolytic assay) of 85% and mean sustained reduction greater than 76%.

Maximum mean reduction in Wieslab AP (alternative pathway) of 100% and mean sustained reduction greater than 89%.

Duration of effect supportive of once every three months or less frequent subcutaneous dosing in later-stage studies

Effects on proteinuria (too much protein in the urine): The mean reduction in spot UPCR was 41%, and the maximum individual reduction was 89%.

In January, the U.S. Food and Drug Administration accepted Arrowhead Pharmaceuticals’ New Drug Application for investigational plozasiran for familial chylomicronemia syndrome, a severe and rare genetic disease. The FDA provided a Prescription Drug User Fee Act (PDUFA) action date of November 18, 2025, and indicated it is not currently planning to hold an advisory committee meeting.

In February, Arrowhead Pharmaceuticals ( ARWR ) closed a global licensing and collaboration agreement with Sarepta Therapeutics Inc ( SRPT ). Arrowhead receives a $500 million upfront payment and $325 million through Sarepta stock.

Price Action: ARWR stock is down 8.72% at $15.49 at the last check Monday.

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