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ARWR: Better Than Anticipated Interim Data for ARO-AAT…


By David Bautz, PhD



Business Update

Positive Interim Data for ARO-AAT

On September 16, 2020, Arrowhead Pharmaceuticals, Inc. (NASDAQ:ARWR) announced interim 24-week biopsy data for four patients from AROAAT2002, an open label Phase 2 clinical trial of ARO-AAT, which is being developed to treat alpha-1 antitrypsin deficiency (AATD).

The company announced that three out of four subjects experienced a decline in intra-hepatic mutant AAT protein (Z-AAT) polymer and that one patient showed a reduction of 97%. Management had previously indicated that they did not anticipate seeing a reduction in Z-AAT polymer this early in the trial, and with a reduction of up to 97% in one patient these results clearly exceeded those expectations and could lead to a significant positive effect for AATD patients.

Additional positive indications from this trial included serum and intra-hepatic reductions in Z-AAT monomer of up to 93% and 95%, respectively, along with maximum reductions in ALT and GGT of 66% and 58%, respectively. All of the patients showed improved transient elastography FibroScan values, with three out of four patients showing reductions of >20%.

These data point to ARO-AAT having a clear, positive impact on AATD and we anticipate the company presenting the full data set later this year. The company has submitted a late breaking abstract to the American Association for the Study of Liver Disease (AASLD) and, if accepted, the data will be presented at the meeting in November.

The AROAAT2002 study is expected to enroll approximately 16 patients, with liver biopsies taken at 0, 6, 12, 18, and 24 months. The company is also conducting the Phase 2/3 SEQUOIA trial, in which patients will be treated for approximately two years. However, given the unexpectedly positive results seen at the six-month timepoint in AROAAT2002, the company may consider approaching regulators to streamline and accelerate that study.


We are very encouraged by the surprising reduction noted in Z-AAT polymer along with the robust reductions noted in Z-AAT monomer and other liver biomarkers at the 6-month timepoint and believe this could be indicative of the potential for ARO-AAT to have a profoundly positive effect for patients. We look forward to the full dataset being presented later this year. Based on these results we are increasing our probability of success for ARO-AAT from 60% to 70%, which has increased our valuation to $61.

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