Arrowhead Hosts Investor & Analyst R&D Day to Introduce TRiM™ Platform and Lead RNAi-based Drug Candidates

PASADENA, Calif.–(BUSINESS WIRE)– Arrowhead Pharmaceuticals, Inc. (NASDAQ: ARWR), is hosting an investor &
analyst R&D day in New York today to introduce its proprietary Targeted
RNAi Molecule (TRiM^TM) platform and review its pipeline of
RNAi therapeutic candidates.

Chris Anzalone, Ph.D., president and chief executive officer of
Arrowhead Pharmaceuticals, said: “We are excited to introduce our new
TRiM^TM platform and the first development candidates to be
advanced: ARO-HBV, targeting chronic hepatitis B infection; ARO-AAT,
targeting alpha-1 antitrypsin deficiency liver disease; and, ARO-APOC3
and our newest candidate ARO-ANG3, targeting hypertriglyceridemia. TRiM^TM
is characterized by its ligand-mediated delivery strategy, structural
simplicity, and trigger selection technology, which is an important part
of TRiM^TM that enables us to rapidly develop what we believe
are optimal RNAi therapies. It also allows tissue-specific targeting and
to that end we are announcing today that we have seen some very exciting
results using TRiM^TM technology to target genes and diseases
in the lung. This opens up a host of new opportunities for disease
targets previously not accessible to RNAi therapeutics and Arrowhead is
thrilled to be leading the industry in these efforts.”

The R&D day will feature presentations by key opinion leaders, Jeffrey
Teckman, M.D. (St. Louis University School of Medicine), Stephen
Locarnini, M.D., Ph.D. (Victorian Infectious Diseases Reference
Laboratory), and Ira Goldberg, M.D. (NYU Langone Medical Center), as
well as Arrowhead management.

A live and archived webcast of the event can be accessed on the Events
and Presentations page on the Investors section of the Arrowhead
website at http://ir.arrowheadpharma.com/events.cfm.

Agenda and Approximate Times for Discussion Topics

12:00-12:45 Lunch
1:00-1:05 Welcome and Introductions – Vince
Anzalone, CFA
1:05-1:35 TRiM^TM Platform and Pipeline
Review – Chris Anzalone, Ph.D.
1:35-1:55 Hepatitis B – Stephen
Locarnini, M.D., Ph.D.
1:55-2:05 ARO-HBV – Bruce Given, M.D.
2:05-2:25
Alpha-1 Antitrypsin Deficiency Liver Disease – Jeffrey Teckman, M.D.
2:25-2:35
ARO-AAT – Bruce Given, M.D.
2:35-2:55 Hypertriglyceridemia – Ira
Goldberg, M.D.
2:55-3:05 ARO-APOC3 and ARO-ANG3 – Bruce Given, M.D.
3:05-3:15
Concluding Remarks – Chris Anzalone, Ph.D.
3:15-3:35 Q & A – Panel

Select R&D Day Highlights

Targeted RNAi Molecule Platform (TRiM^TM)

Arrowhead’s Targeted RNAi Molecule platform, or TRiM^TM,
utilizes ligand-mediated delivery and is designed to enable multi-tissue
targeting, while being structurally simple. Active targeting has been
core to Arrowhead’s development strategy and the TRiM^TM
platform builds on more than a decade of work on actively targeted drug
delivery vehicles. Arrowhead scientists now have the ability to
progressively “TRiM” away extraneous features and chemistries and retain
optimal pharmacologic activity.

New drug candidates utilizing this technology can achieve high levels of
target gene knockdown, without an active endosomal escape component, as
was required with prior technology platforms.

The TRiM^TM platform represents an evolution in RNAi
therapeutics from biologic complexity to small molecule precision and
execution. The TRiM^TM platform comprises the following
components optimized, as needed, for each drug candidate: high affinity
targeting ligands; various linker chemistries; structures that enhance
pharmacokinetics; and highly potent RNAi triggers with sequence specific
stabilization chemistries. The platform offers several competitive
advantages, including:

• Simplified manufacturing at reduced cost
• Multiple routes of administration (subcutaneous, intravenous, and
  inhaled)
• Faster time to clinical candidates
• Wide safety margins
• Promise of taking RNAi to tissues beyond the liver

Extra-Hepatic Targeting

Arrowhead believes that for RNAi to reach its true potential, it must
target organs outside the liver. Arrowhead is leading this expansion
with the TRiM^TM platform that holds the promise of reaching
multiple tissues, including the lung and tumors. ARO-Lung1, the first
candidate against an undisclosed gene target in the lung, reached almost
90% target knockdown following inhaled administration in rodents. In
addition, the ARO-HIF2 candidate targeting renal cell carcinoma achieved
85% target gene knockdown in a rodent tumor model. Clinical Trial
Authorization (CTA) filings are planned in Q4 2018 and in 2019 for
ARO-Lung1 and ARO-HIF2, respectively.

ARO-AAT

ARO-AAT, Arrowhead’s second generation subcutaneously administered
clinical candidate for the treatment of alpha-1 antitrypsin deficiency
liver disease, achieved up to 92% knockdown in monkeys, thought to be
near complete suppression of hepatic production of the alpha-1
antitrypsin protein. In non-GLP rat and monkey exploratory toxicology
studies, no changes in clinical chemistries were observed and no
histopathology suggestive of organ toxicity at doses up to 300 mg/kg
(100x expected human dose). Arrowhead plans to file a CTA in Q1 2018 to
initiate clinical studies, pending completion of GLP toxicology studies.

ARO-HBV

ARO-HBV, Arrowhead’s third generation subcutaneously administered
clinical candidate for the treatment of chronic hepatitis B virus
infection, achieved up to 99.9% knockdown of hepatitis B surface antigen
(HBsAg), e-antigen (HBeAg), and HBV DNA in rodent models. In a non-GLP
rat exploratory toxicology study, no changes in clinical chemistries or
histopathology changes suggestive of organ toxicity were observed at
doses up to 300 mg/kg (75-100x expected human dose). Arrowhead plans to
file a CTA in Q2 2018 to initiate clinical studies, pending completion
of cross-reactivity and GLP toxicology studies.

ARO-APOC3 and ARO-ANG3

Arrowhead is expanding its cardiovascular disease portfolio utilizing
the TRiM™ platform. Added to existing programs, ARO-LPA and ARO-AMG1,
both partnered with Amgen; will be ARO-APOC3, targeting apolipoprotein
C-III, and ARO-ANG3, targeting angiopoietin-like protein 3 (ANGPTL3).
ARO-APOC3 and ARO-ANG3 will both be developed for the treatment of
hypertriglyceridemia. CTA filings are planned for one or both candidates
by the end of 2018.

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.

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

This news release contains forward-looking statements within the
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Litigation Reform Act of 1995. These statements are based upon our
current expectations and speak only as of the date hereof. Our actual
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candidates, the timing for starting and completing clinical trials,
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Source: Arrowhead Pharmaceuticals, Inc.

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