The preliminary results from Phase 1/2a clinical trials of the company’s RNA interference (RNAi) therapies suggest the treatments may reduce body fat and improve metabolic health in patients, particularly those with type 2 diabetes.

  • The interim data show that ARO-INHBE, especially when combined with tirzepatide, doubled weight loss and tripled reductions in visceral fat.
  • In adults with obesity, a single 400 mg dose of ARO-INHBE reduced serum Activin E by a mean of 85%, reaching a maximum reduction of 94%.
  • ARO-ALK7 became the first RNAi therapy to silence an adipocyte gene in humans.

Arrowhead Pharmaceuticals Inc. (ARWR) stock jumped over 15% in Tuesday’s premarket, after it released early data from its Phase 1/2a clinical trials of its RNA interference (RNAi) therapies, ARO-INHBE and ARO-ALK7, targeting obesity. 

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The preliminary results suggest these investigational treatments may reduce body fat and improve metabolic health in patients, particularly those with type 2 diabetes.

Promising Fat Reduction

The interim data show that ARO-INHBE, especially when combined with tirzepatide, a GLP-1/GIP receptor co-agonist, doubled weight loss and tripled reductions in visceral fat, total fat, and liver fat compared with tirzepatide alone.

The findings mark the first human evidence that targeting the Activin E/ALK7 pathway could enhance weight loss beyond that achieved by existing incretin therapies. In adults with obesity, a single 400 mg dose of ARO-INHBE reduced serum Activin E by a mean of 85%, reaching a maximum reduction of 94%.

On Stocktwits, retail sentiment around Arrowhead stock jumped to ‘bullish’ from ‘bearish’ territory. Message volume shifted to ‘high’ from ‘low’ levels in 24 hours. 

ARWR’s Sentiment Meter and Message Volume as of 08:00 a.m. ET on Jan. 6, 2026 | Source: Stocktwits

Clinical Highlights

ARO-INHBE monotherapy at week 16 led to a 9.9% reduction in visceral fat, a 38% drop in liver fat, and a 3.6% increase in lean muscle. Two doses at week 24 further improved visceral fat reduction to 15.6% after adjusting for placebo. 

Combined with tirzepatide, ARO-INHBE achieved roughly double the weight loss and triple the fat reduction compared to tirzepatide alone.

ARO-ALK7 became the first RNAi therapy to silence an adipocyte gene in humans, reducing ALK7 mRNA in fat tissue by an average of 88% at the 200 mg dose, with a peak reduction of 94%. Early data also showed a 14.1% reduction in visceral fat after a single dose at week 8, adjusted for placebo.

ARWR stock has gained over 227% in the last 12 months. 

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