Arrowhead Pharmaceuticals Inc (NASDAQ: ARWR), a provider of RNAi-based therapeutics, on Monday announced topline results from Part 2 of its Phase 1/2 study of ARO-C3, an investigational RNA interference (RNAi) therapy targeting complement component 3 (C3) for complement-mediated diseases. The study demonstrated significant reductions in alternative pathway complement activity and proteinuria in patients with IgA nephropathy (IgAN).

Patients receiving ARO-C3 showed mean sustained reductions of ≥87% in C3, ≥76% in serum AH50, and ≥89% in Wieslab AP through week 24. Proteinuria, measured by spot urine protein-to-creatinine ratio (UPCR), decreased by an average of 41%, with a maximum individual reduction of 89%.

ARO-C3 was well tolerated, with no serious or severe treatment-emergent adverse events. The most common mild side effects included headache, cough and nasopharyngitis. No infections with encapsulated organisms were reported.

The company plans to present additional data at a medical conference in 2025.