Arrowhead Pharmaceuticals Initiates Phase 2 Study of ARC-AAT

PASADENA, Calif.–(BUSINESS WIRE)–

Arrowhead Pharmaceuticals Inc. (NASDAQ: ARWR) today announced that it

initiated a Phase 2 clinical study of ARC-AAT, an investigational

RNAi-based medicine for the treatment of liver disease associated with

alpha-1 antitrypsin deficiency (AATD). The study is designed to evaluate

safety and tolerability and determine the effect of multiple doses of

ARC-AAT on levels of circulating and intrahepatic alpha-1 antitrypsin as

evidenced by changes in liver biopsy in patients with AATD.

Bruce Given, M.D., chief operating officer and head of R&D at Arrowhead

said, “There remains no medical treatment for the liver disease

associated with AATD, which is increasingly being recognized by patients

and physicians as a serious problem. Our Phase 2 2001 study should give

us, and the AATD community in general, the first insights into whether

ARC-AAT can stop the progression of liver disease and possibly even

allow the liver to recover and heal existing damage. This would be a

significant breakthrough for patients.”

The ARC-AAT Phase 2 study (ARCAAT2001) is a multi-center, open-label,

multiple dose-escalation study of ARC-AAT in patients with AATD. In

total, the study will consist of at least 8 and a maximum of 12

participants. Two dose levels, 4 mg/kg and 6 mg/kg, will be evaluated in

two separate cohorts. All subjects will receive a pre-dose biopsy, seven

doses of ARC-AAT (once every 28 days), and a post-dose biopsy completed

at Day 183. The study will be conducted at multiple centers in Canada,

Ireland, and Sweden. The Company may add additional centers in other

countries, pending regulatory and ethics review.

About ARC-AAT

Arrowhead’s ARC-AAT is being investigated for the treatment of liver

disease associated with alpha-1 antitrypsin deficiency (AATD), a rare

genetic disease that severely damages the liver and lungs of affected

individuals. The mean estimated prevalence of AATD in the U.S is 1 per

3000-5000, or approximately 100,000 patients. AATD is also an important

cause of pediatric liver disease with an estimated prevalence in

children of approximately 20,000 patients, and 50-80% likely to manifest

liver disease during childhood. It is a rare disease that is frequently

misdiagnosed or undiagnosed. ARC-AAT employs a novel unlocked nucleobase

analog (UNA) containing RNAi trigger molecule designed for systemic

delivery using the Dynamic Polyconjugate delivery system.

ARC-AAT is highly effective at knocking down the Alpha-1 antitrypsin

(AAT) gene transcript and reducing the hepatic production of the mutant

AAT (Z-AAT) protein in animal models. Reduction of liver production of

the inflammatory Z-AAT protein, which is believed to be the cause of

progressive liver disease in AATD patients, is important as it is

expected to halt the progression of liver disease and potentially allow

fibrotic tissue repair. ARC-AAT was granted orphan drug designation in

both the United States and in Europe, the latter being held on

Arrowhead’s behalf by a local EU representative Pharma Gateway AB.

Arrowhead is conducting a Phase 1 clinical study of ARC-AAT, with part A

in healthy volunteers (now complete) and part B in AATD patients, and a

Phase 2 multiple dose study in AATD patients.

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. The company’s pipeline includes ARC-520 and ARC-521 for

chronic hepatitis B virus infection, ARC-AAT for liver disease

associated with alpha-1 antitrypsin deficiency, ARC-F12 for hereditary

angioedema and thromboembolic disorders, ARC-LPA for cardiovascular

disease, and ARC-HIF2 for renal cell carcinoma.

For more information, please visit www.arrowheadpharma.com,

or follow us on Twitter @ArrowheadPharma.

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Safe Harbor Statement under the Private Securities Litigation Reform

Act:

This news release contains forward-looking statements within the

meaning of the “safe harbor” provisions of the Private Securities

Litigation Reform Act of 1995. These statements are based upon our

current expectations and speak only as of the date hereof. Our actual

results may differ materially and adversely from those expressed in any

forward-looking statements as a result of various factors and

uncertainties, including our ability to finance our operations, the

future success of our scientific studies, our ability to successfully

develop drug candidates, the timing for starting and completing clinical

trials, rapid technological change in our markets, and the enforcement

of our intellectual property rights. Our most recent Annual Report on

Form 10-K and subsequent Quarterly Reports on Form 10-Q discuss some of

the important risk factors that may affect our business, results of

operations and financial condition. We assume no obligation to update or

revise forward-looking statements to reflect new events or circumstances.

DYNAMIC POLYCONJUGATES is a trademark of Arrowhead

Pharmaceuticals, Inc.

Source: Arrowhead Pharmaceuticals, Inc.

Arrowhead Pharmaceuticals, Inc.
Vince Anzalone, CFA
626-304-3400
ir@arrowheadpharma.com
or
Investor

Relations:
The Trout Group
Chad Rubin
646-378-2947
ir@arrowheadpharma.com
or
Media:
Russo

Partners
Matt Middleman, M.D.
212-845-4272
matt.middleman@russopartnersllc.com

Source: Arrowhead Pharmaceuticals, Inc.

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