Roche and Prothena Enter Into Worldwide Collaboration to Co-Develop and Co-Promote Antibodies for Treatment of Parkinson's

Roche and Prothena Enter Into Worldwide Collaboration to Co-Develop and
Co-Promote Antibodies for Treatment of Parkinson's Disease

  *Prothena to receive up to $600 million, inclusive of upfront payment and
    near-term clinical milestone totaling $45 million, as well as 30 percent
    of U.S. profits, and up to double-digit royalties on ex-U.S. net sales
  *Prothena to host conference call/webcast today (December 11) at 4:30 p.m.
    Eastern Time

BASEL, Switzerland and DUBLIN, Ireland, Dec. 11, 2013 (GLOBE NEWSWIRE) --
Roche (SIX:RO) (SIX:ROG) (OTCQX:RHHBY) and Prothena Corporation plc
(Nasdaq:PRTA), announced today that they have entered into a worldwide
collaboration to develop and commercialize antibodies that target
alpha-synuclein, including PRX002, Prothena's monoclonal antibody for the
treatment of Parkinson's disease, which is currently in preclinical
development and is expected to enter Phase 1 clinical trials in patients with
Parkinson's disease in 2014.

Synuclein proteins are a family of charged proteins found throughout the body.
One protein from this family, alpha-synuclein, is found extensively in neurons
and is a major component of pathological inclusions that characterize several
neurodegenerative disorders, including Parkinson's disease, dementia with Lewy
bodies, neurodegeneration with brain iron accumulation type 1, and multiple
system atrophy, which collectively are termed synucleinopathies.

"Parkinson's is a severely debilitating and progressive neurodegenerative
disease that leads to both a gradual worsening of motor function and cognitive
and behavioral alterations," said Luca Santarelli, Head of Neuroscience and
Small Molecules Research at Roche. "Currently, there is no treatment that
modifies its course, and by targeting one of Parkinson's key molecular
determinants, PRX002 has the potential to slowdown or reduce its progression.
This approach is consistent with our strategy in other neurodegenerative
diseases, such as Alzheimer's, Huntington, Multiple Sclerosis or Spinal
Muscular Atrophy, where we target the molecular pathophysiology and intervene
early with the objective to slowdown or halt the progression of disease."

"We are excited to be working with Roche to develop PRX002 as a disease
modifying treatment for Parkinson's disease and potentially other
synucleinopathies. Roche is a global leader in drug development with
significant experience in developing drugs to treat neurological diseases,"
said Dale Schenk, PhD, President and Chief Executive Officer of Prothena. "By
combining Roche's expertise with our own, this collaboration will greatly
enhance our development efforts with PRX002 and allow us to move forward in a
more comprehensive manner. This collaboration also represents an important
milestone in our growth as we continue to execute on our corporate strategy to
be a leading fully-integrated biotechnology company."

Roche and Prothena will collaborate on the development of PRX002 for
Parkinson's disease and potentially other synucleinopathies. Prothena also has
an option to co-promote PRX002 in the U.S. In the U.S., the companies will
share all development and commercialization costs, as well as profits, on a
70/30 basis (70% Roche and 30% Prothena). Outside the U.S., Roche will have
sole responsibility for developing and commercializing PRX002 and will pay
Prothena up to double-digit royalties on net sales.

Under the terms of the agreement, Prothena will receive an upfront payment and
near-term clinical milestone totaling $45 million. Prothena is also eligible
to receive additional payments of up to $380 million upon the achievement of
development, regulatory and first commercial sales milestones plus up to an
additional $175 million in ex-U.S. commercial milestone payments. The total
worldwide upfront and milestone payments may amount up to $600 million.

Also as part of the agreement, Roche and Prothena will initiate a research
collaboration focused on optimizing early stage antibodies targeting
alpha-synuclein including incorporation of Roche's proprietary Brain Shuttle™
technology to increase delivery of therapeutic antibodies to the brain.

The transaction is subject to customary regulatory clearances including
expiration of the applicable Hart- Scott-Rodino waiting period. Prothena's
legal and financial advisers on the transaction were Latham & Watkins LLP and
BioAsset Advisors, respectively.

Conference Call

Prothena will host a conference call this afternoon (December 11) at 4:30 p.m.
Eastern Time (1:30 p.m. Pacific Time) to discuss this announcement.

The conference call and live audio webcast can be accessed as follows:

Dial-in: 877-887-5215 (U.S. toll free) or 315-625-3069 (international)

Conference ID Number: 21227734

Webcast: http://ir.prothena.com

A replay of the webcast will be available for 30 days following the conference
call date via dial-in to 855-859-2056 (U.S. toll free) or 404-537-3406
(international), Conference ID Number 21227734, or via webcast on the investor
relations section of Prothena's website at http://ir.prothena.com.

About Parkinson's disease

Parkinson's disease is the second most common neurodegenerative disorder after
Alzheimer's disease. There are an estimated seven to ten million patients with
Parkinson's disease worldwide. Current treatments for Parkinson's disease are
effective at managing the early motor symptoms of the disease, mainly through
the use of levodopa and dopamine agonists. As the disease progresses and
dopaminergic neurons continue to be lost, these drugs eventually become less
effective at treating the symptoms.

About PRX002

PRX002, a monoclonal antibody targeting alpha-synuclein, has been tested in
various cellular and animal models of synuclein-related disease and has shown
in multiple transgenic mouse models of Parkinson's disease, that passive
immunization with 9E4, the murine version of PRX002, reduced the appearance of
synuclein pathology, protected synaptic connections and improved performance
by the mice in behavioral testing. PRX002 may slow or reduce the
neurodegeneration associated with synuclein misfolding and/or cell-to-cell
transmission of pathogenic forms of synuclein.

About Prothena

Prothena Corporation plc is a clinical stage biotechnology company focused on
the discovery, development and commercialization of novel antibodies for the
potential treatment of a broad range of diseases that involve protein
misfolding and cell adhesion, particularly on the discovery, development and
commercialization of potential therapeutic monoclonal antibodies directed
specifically to disease-causing proteins. These potential therapies have a
broad range of indications, including AL and AA forms of amyloidosis
(NEOD001), Parkinson's disease and related synucleinopathies (PRX002), and
novel cell adhesion targets involved in inflammatory disease and metastatic
cancers (PRX003). Prothena conducts its operations through its wholly- owned
subsidiaries, Neotope Biosciences Limited, Onclave Therapeutic Limited and
Prothena Biosciences Inc. For more information, please visit www.prothena.com.

About Roche Neuroscience

Roche is working on new molecular entities in neuroscience that could become
the next generation of medicines for a range of diseases including
schizophrenia, multiple sclerosis, depression, neurodevelopmental disorders,
Parkinson's disease and Alzheimer's disease. With one of the strongest
neuroscience pipelines in the industry, and by working closely with academic
institutions, biotech companies, and forming public-private partnerships,
Roche's focus is on expanding its neuroscience franchise to better serve
patients.

About Roche

Headquartered in Basel, Switzerland, Roche is a leader in research-focused
healthcare with combined strengths in pharmaceuticals and diagnostics. Roche
is the world's largest biotech company, with truly differentiated medicines in
oncology, infectious diseases, inflammation, metabolism and neuroscience.
Roche is also the world leader in in vitro diagnostics and tissue-based cancer
diagnostics, and a frontrunner in diabetes management. Roche's personalised
healthcare strategy aims at providing medicines and diagnostic tools that
enable tangible improvements in the health, quality of life and survival of
patients. In 2012 Roche had over 82,000 employees worldwide and invested over
8 billion Swiss francs in R&D. The Group posted sales of 45.5 billion Swiss
francs. Genentech, in the United States, is a wholly owned member of the Roche
Group. Roche is the majority shareholder in Chugai Pharmaceutical, Japan. For
more information, please visit www.roche.com.

Forward-looking Statements

This press release contains forward-looking statements within the meaning of
the Section 27A of the Securities Act of 1933 and Section 21E of the
Securities Exchange Act of 1934. These statements relate to, among other
things, the ability to maintain HSR compliance, the ability of Prothena and
Roche to successfully research, develop and commercialize antibodies that
target alpha-synuclein (including PRX002), the ability of Prothena and Roche
to obtain regulatory approval to manufacture, market and sell PRX002 in or
outside of the United States, the efficacy of PRX002 as a treatment for
Parkinson's disease or other synucleinopathies, the ability for Prothena to
achieve milestones or receive royalties under the agreement in order to
receive payments thereunder, and the expected timing of PRX002 clinical
development, including Phase 1 clinical trials. These forward-looking
statements are identified by their use of terms and phrases such as
"anticipate," "believe," "could," "should," "estimate," "expect," "intend,"
"may," "plan," "predict," "project," "potential," "target," "will" and similar
terms and phrases, including references to assumptions. These statements are
based on assumptions that may not prove accurate. Actual results could differ
materially from those anticipated due to known and unknown risks,
uncertainties and other factors including, but not limited to the risks and
uncertainties described in Prothena's SEC filings, including the "Risk
Factors" section of Prothena's Annual Report on Form 10-K and Quarterly
Reports on Form 10-Q. Prothena undertakes no obligation to update publicly any
forward-looking statements contained in this press release as a result of new
information, future events or changes in Prothena's expectations.

CONTACT: Prothena
         Investors: Tran Nguyen, CFO
         650-837-8535, IR@prothena.com
         Media: Anita Kawatra
         646-256-5116, anita.kawatra@prothena.com
        
         Roche Partnering
         Emilie Vincent
         Head of Roche Partnering Communications
         emilie.vincent@roche.com
 
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