Prothena : Corporate Overview

Prothena Corporate Overview

December 12, 2020

Forward-Looking Statements

This overview contains forward-looking statements. These statements relate to, among other things: the sufficiency of our cash position to fund advancement of a broad pipeline; the continued advancement of our discovery and preclinical pipeline; our goal of building a neurotherapeutics engine; the design, proposed mechanism of action and possible clinical benefits of prasinezumab (PRX002/RG7935), and its potential as a treatment for Parkinson's disease; the design of the Phase 2 PASADENA study of prasinezumab; the expected timing of announcing additional data from the Phase 2 study of prasinezumab; the design and timing of future clinical studies of prasinezumab; amounts we might receive under our collaboration with Roche; the design, proposed mechanism of action and possible clinical benefits of PRX004, and its potential as a treatment for ATTR amyloidosis; the potential of PRX004 to complement proven therapies and offer superior efficacy; the design and capabilities of our misTTR assay for hereditary ATTR; the design of the Phase 1 study of PRX004; the design and timing of future clinical studies of PRX004; amounts we might receive under our collaboration with Bristol-Myers Squibb; potential Tau and abeta indications; the potential superior attributes and efficacy of novel epitopes and antibodies we have identified in our Tau, abeta and TDP-43 programs, including PRX005 and PRX012; our potential to advance, initiate and complete IND enabling studies for our tau and abeta programs; and our ability to progress our vaccine program. These forward-looking statements are based on estimates, projections and assumptions that may prove not to be accurate, and actual results could differ materially from those anticipated due to known and unknown risks, uncertainties and other factors, including but not limited to the effects on our business of the worldwide COVID-19 pandemic and the risks, uncertainties and other factors described in the "Risk Factors" sections of our Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on March 3, 2020, as well as discussions of potential risks, uncertainties, and other important factors in our subsequent filings with the SEC. We undertake no obligation to update publicly any forward-looking statements contained in this presentation as a result of new information, future events or changes in our expectations.

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Novel Therapeutics for Neurodegenerative and Rare Peripheral Amyloid Diseases

DEEP PIPELINE

Mid- and early-stage product candidates in multiple neurodegenerative and rare peripheral amyloid diseases

PROLIFIC DISCOVERY ENGINE

Advancing new targets and candidates based on decades of experience in fundamental neuroscience discoveries

WORLD CLASS COLLABORATIONS

Strong collaborations with Roche and Bristol Myers Squibb, and complementary expertise, accelerate our pipeline

EXPERIENCED TEAM

Deep scientific expertise in protein dysregulation and ability to integrate insights around neurological dysfunction

STRONG CAPITAL POSITION

$317 million* at end of 3Q2020 funds our current pipeline through potentially significant value inflection points

* Includes cash, cash equivalents and restricted cash

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Robust R&D Pipeline

Focused on neurodegenerative and rare peripheral amyloid diseases

Program / Target	Discovery	Preclinical	Phase 1	Phase 2	Phase 3	Biomarker	Commercial
Enabled	Rights
Prasinezumab
(PRX002/RG7935)	PASADENA (Phase 2)				ü MRI-ASL
α−synuclein
Parkinson's Disease
PRX004 / TTR	Phase 1					ü Non-native TTR*
ATTR Amyloidosis
PRX005 / Tau	Preclinical					ü PET-tau	**
AD, PSP, FTD, CTE
PRX012 / Aβ	Preclinical					ü PET-Aβ
AD
TDP-43	Discovery						**
ALS, FTD
Undisclosed	Discovery					ü	**
Neurodegeneration
Vaccine/Aβ + Tau	Discovery					ü PET-imaging
AD
Undisclosed	Discovery					ü CSF
AD/Down Syndrome

*Prothena's proprietary assay for non-native TTR in hereditary ATTR Amyloidosis (hATTR)

Aβ, Abeta; AD, Alzheimer's disease; PSP, progressive supranuclear palsy; FTD, frontotemporal dementia; CTE,	mAb		Small
chronic traumatic encephalopathy ALS, amyotrophic lateral sclerosis; MRI-ASL, magnetic resonance-arterial	Vaccine
Molecule
spin labelling; PET, positron emission tomography; mAb, monoclonal antibody

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