Arrowhead Pharmaceuticals released early clinical data showing its RNAi candidates produced meaningful fat loss when combined with Lilly’s tirzepatide (Zepbound), including disproportionate reductions in visceral and liver fat in an initial cohort. The company said the results mark proof-of-concept for adipose delivery of its siRNA agents. Interim Phase 1/2a readouts reported patients on the combination lost more weight and more visceral fat than tirzepatide alone; BioCentury highlighted Arrowhead’s ALK7 and INHBE-related data as standing out. Arrowhead plans to advance the programs toward Phase 2 testing based on the signals. The results could intensify the race for longer-duration and combination obesity therapeutics and raise strategic questions about positioning RNAi as an adjunct to GLP-1/GIP receptor agonists. Sponsors and investors will watch subsequent cohort sizes, durability, and safety readouts to gauge commercial potential.