Arrowhead Completes Enrollment in Phase 1 Study of ARO-AAT for Treatment of Alpha-1 Liver Disease

Arrowhead Pharmaceuticals Inc. (NASDAQ: ARWR) today announced that it
has completed enrollment of a Phase 1 clinical study of ARO-AAT, the
company’s second generation subcutaneously administered RNA interference
(RNAi) therapeutic being developed as a treatment for a rare genetic
liver disease associated with alpha-1 antitrypsin deficiency. Two
planned cohorts at a dose of 400 mg were eliminated because maximal
activity appeared to occur at lower doses than expected. The company
intends to submit a late-breaking abstract with initial clinical data on
ARO-AAT to the Liver Meeting®, the Annual Meeting of the
American Association for the Study of Liver Disease (AASLD), being held
in November 2018.

Chris Anzalone, Ph.D., Arrowhead’s president and chief executive
officer, said, “The ARO-AAT Phase 1 study provides the first readout on
pharmacologic activity for a therapeutic leveraging our proprietary
Targeted RNAi Molecule, or TRiM™, platform. We have escalated above a
dose that we believe achieves maximal activity, and all doses to date
appear to be generally well-tolerated.”

AROAAT1001 (NCT03362242)
is a Phase 1 single- and multiple-ascending dose study to evaluate the
safety, tolerability, pharmacokinetics, and effect of ARO-AAT on serum
alpha-1 antitrypsin levels in healthy adult volunteers. The study
includes 7 cohorts in which 16 subjects receive placebo and 28 subjects
receive single or multiple doses of ARO-AAT at doses of 35, 100, 200, or
300 mg. Additional cohorts were planned at a dose of 400 mg, but were
deemed unnecessary based on observed activity at lower doses.

About Arrowhead Pharmaceuticals

Arrowhead Pharmaceuticals develops medicines that treat intractable
diseases by silencing the genes that cause them. Using a broad portfolio
of RNA chemistries and efficient modes of delivery, Arrowhead therapies
trigger the RNA interference mechanism to induce rapid, deep, and
durable knockdown of target genes. RNA interference, or RNAi, is a
mechanism present in living cells that inhibits the expression of a
specific gene, thereby affecting the production of a specific protein.
Arrowhead’s RNAi-based therapeutics leverage this natural pathway of
gene silencing.

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Litigation Reform Act of 1995. These statements are based upon our
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candidates, the timing for starting and completing clinical trials,
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and subsequent Quarterly Reports on Form 10-Q discuss some of the
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Source: Arrowhead Pharmaceuticals, Inc.

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