Arrowhead shoots up as Phase II interim data from ARO-AAT surprises

Arrowhead Pharmaceuticals’ (Nasdaq: ARWR) shares were up more than 55% at $52.43 late-morning, after it released positive Phase II interim results on RNAi candidate ARO-AAT for the treatment of liver disease associated with alpha-1 antitrypsin deficiency, that even surprised the US biotech company’s researchers

The results show clear evidence of a meaningful pharmacodynamic effect by ARO-AAT, leading to improvements in relevant biomarkers, including substantial reductions in intra-hepatic mutant AAT protein (Z-AAT), both Z-AAT monomer and Z-AAT polymer; improvements in liver stiffness based on FibroScan; and, a decrease in alanine aminotransferase (ALT) and gamma-glutamyl transferase (GGT), both serum biomarkers of liver injury.

After 24 weeks of treatment with investigational ARO-AAT in the AROAAT2002 study, serum and total intra-hepatic Z-AAT decreased in all four patients by up to 93% and 95%, respectively. Three of four patients demonstrated reductions from baseline in intra-hepatic Z-AAT polymer, with a maximum reduction of 97%. All four patients showed reductions in ALT and GGT, with maximum reductions of 66% and 58%, respectively. All patients demonstrated improved transient elastography FibroScan values, with three of four patients exhibiting greater than 20% reductions.