Arrowhead Receives Regulatory Approval to Begin Phase 2a Trial of Chronic Hepatitis B Candidate ARC-520

  Arrowhead Receives Regulatory Approval to Begin Phase 2a Trial of Chronic
  Hepatitis B Candidate ARC-520

Business Wire

PASADENA, Calif. -- March 3, 2014

Arrowhead Research Corporation (NASDAQ: ARWR), a biopharmaceutical company
developing targeted RNAi therapeutics, today announced that it received
regulatory approval to begin a Phase 2a clinical trial of ARC-520, its
RNAi-based drug candidate for the treatment of chronic hepatitis B virus (HBV)
infection. The Hong Kong Department of Health issued a Certificate for
Clinical Trial, allowing the Company to proceed with its planned single-dose
study of ARC-520 in two cohorts at two dose levels to be conducted at Queen
Mary Hospital and Prince of Wales Hospital in Hong Kong. A site initiation was
completed and patient screening will initiate shortly. The Company expects top
line study results to be available in the third quarter of 2014.

The Phase 2a study is a multicenter, randomized, double-blind,
placebo-controlled, dose-escalation study to determine the depth and duration
of hepatitis B surface antigen (HBsAg) reduction after a single intravenous
dose of ARC-520 in combination with entecavir in patients with chronic HBV
infection. Single doses of ARC-520 will be evaluated at up to two ascending
doses of 1.0 mg/kg and 2.0 mg/kg. At each of the two dose levels to be
evaluated, a cohort of 8 patients will be enrolled with 6 being dosed with
ARC-520 and 2 being dosed with placebo. This study will be conducted in adult
male and female patients aged 16 to 65 years, with immune active chronic HBV
infection, HBV e antigen (HBeAg) negativity, and ongoing entecavir therapy.

The primary objective of the study is to evaluate the depth and duration of
HBsAg decline in response to a single dose of ARC-520 in combination with
entecavir. Secondary objectives include evaluation of safety and tolerability
and pharmacokinetic (PK) measures. Additional exploratory pharmacodynamics
(PD) objectives include evaluation of the effect of ARC-520 on HBV DNA serum
titers and antibodies to HBsAg (anti-HBs).

About ARC-520

Arrowhead’s RNAi-based candidate ARC-520 is designed to treat chronic HBV
infection by reducing the expression and release of new viral particles and
key viral proteins. The goal is to achieve a functional cure, which is an
immune clearant state characterized by hepatitis B s-antigen negative serum
with or without sero-conversion. The siRNAs in ARC-520 intervene at the mRNA
level, upstream of where nucleotide and nucleoside analogues act. In transient
and transgenic mouse models of HBV infection, a single co-injection of
Arrowhead’s DPC delivery vehicle with cholesterol-conjugated siRNA targeting
HBV sequences resulted in multi-log knockdown of HBV RNA, proteins and viral
DNA with long duration of effect. Arrowhead has completed enrollment in a
Phase 1 single ascending dose study in normal volunteers. The company is
conducting a single dose Phase 2a study in chronic HBV patients, which it
expects to follow with a multi dose, multi national Phase 2b study.
Approximately 350 million people worldwide are chronically infected with the
hepatitis B virus. Chronic HBV infection can lead to cirrhosis of the liver
and is responsible for 80% of primary liver cancers globally.

About Arrowhead Research Corporation

Arrowhead Research Corporation is a biopharmaceutical company developing
targeted RNAi therapeutics. The company is leveraging its proprietary drug
delivery technologies to develop targeted drugs based on the RNA interference
mechanism that efficiently silences disease-causing genes. Arrowhead
technologies also enable partners to create peptide-drug conjugates that
specifically home to cell types of interest while sparing off-target tissues.
Arrowhead’s pipeline includes clinical programs in chronic hepatitis B virus
and partner-based programs in obesity and oncology.

For more information please visit, or follow
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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. Arrowhead Research
Corporation's 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.


Arrowhead Research Corporation
Vince Anzalone, CFA
The Trout Group
Lauren Glaser
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