UNITED STATES SECURITIES AND EXCHANGE COMMISSION For the year ended December 31, 2022 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Washington, D.C. 20549 For the transition period from to Commission file number: 001-35676 ______________________________________ PROTHENA CORPORATION PUBLIC LIMITED COMPANY (Exact name of registrant as specified in its charter) ______________________________________ Ireland 98-1111119 (State or other jurisdiction of incorporation or ...

Global Neuroscience Collaboration with Bristol Myers Squibb – This propagation of pathology is thought to be mediated by tau "seeds" containing the MTBR of tau2 • Phase 1 SAD data in HVs demonstrated dose-proportional PRX005 concentrations in plasma with robust CNS penetration and generally safe and well tolerated 1Ahmed, Z., Cooper, J.. et al. A novel in vivo model of tau propagation with rapid and progressive neurofibrillary tangle pathology: the pattern of spread is determined by connectivity, not proxim ...

Prothena Corporation plc (NASDAQ:PRTA) Q4 2022 Earnings Conference Call February 23, 2023 4:30 PM ET Company Participants Eric Endicott - Senior Vice President, Corporate Affairs and Communications Gene Kinney - President and Chief Executive Officer Hideki Garren - Chief Medical Officer Tran Nguyen - Chief Financial Officer and Chief Strategy Officer Wagner Zago - Chief Scientific Officer Conference Call Participants Michael Yee - Jefferies Neena Bitritto-Garg - Citi Charles Duncan - Cantor Fitzgerald Jay O ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Commission file number: 001-35676 ______________________________________ Washington, D.C. 20549 ______________________________________ FORM 10-Q _____________________________________ (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2022 Or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 PROTHENA CORPORATION PUBLIC LIMITED ...

PART I. FINANCIAL INFORMATION [Item 1. Financial Statements (unaudited)](index=6&type=section&id=Item%201.%20Financial%20Statements%20%28unaudited%29) The company reported a net loss of $77.5 million for the six months ended June 30, 2022, a significant increase from a net loss of $9.1 million in the same period of 2021, driven by decreased collaboration revenue and increased operating expenses [Condensed Consolidated Balance Sheets](index=6&type=section&id=Condensed%20Consolidated%20Balance%20Sheets) Total assets decreased to $549.6 million as of June 30, 2022, from $609.4 million at year-end 2021, primarily due to a reduction in cash and cash equivalents Condensed Consolidated Balance Sheet Highlights (in thousands) | Balance Sheet Item | June 30, 2022 | December 31, 2021 | | :--- | :--- | :--- | | Cash and cash equivalents | $508,795 | $579,094 | | Total current assets | $521,294 | $584,809 | | Total assets | $549,589 | $609,366 | | Total current liabilities | $40,107 | $33,452 | | Total liabilities | $142,290 | $143,324 | | Total shareholders' equity | $407,299 | $466,042 | [Condensed Consolidated Statements of Operations](index=7&type=section&id=Condensed%20Consolidated%20Statements%20of%20Operations) The company reported net losses of $41.2 million and $77.5 million for Q2 and H1 2022, respectively, driven by a sharp decline in collaboration revenue and increased operating expenses Statements of Operations Summary (in thousands, except per share data) | Metric | Q2 2022 | Q2 2021 | H1 2022 | H1 2021 | | :--- | :--- | :--- | :--- | :--- | | Total Revenue | $1,312 | $60,071 | $2,465 | $60,231 | | Research and development | $31,569 | $21,090 | $58,831 | $42,234 | | General and administrative | $12,952 | $11,032 | $24,787 | $22,157 | | Net income (loss) | $(41,244) | $27,642 | $(77,534) | $(9,093) | | Diluted net income (loss) per share | $(0.88) | $0.58 | $(1.66) | $(0.21) | [Condensed Consolidated Statements of Cash Flows](index=8&type=section&id=Condensed%20Consolidated%20Statements%20of%20Cash%20Flows) Net cash used in operating activities was $72.7 million for H1 2022, a significant shift from cash provided in H1 2021, leading to a $70.3 million decrease in cash and equivalents Cash Flow Summary for the Six Months Ended June 30 (in thousands) | Cash Flow Activity | 2022 | 2021 | | :--- | :--- | :--- | | Net cash provided by (used in) operating activities | $(72,678) | $2,953 | | Net cash used in investing activities | $(183) | $(48) | | Net cash provided by financing activities | $2,562 | $101,546 | | Net increase (decrease) in cash, cash equivalents and restricted cash | $(70,299) | $104,451 | [Notes to Condensed Consolidated Financial Statements](index=11&type=section&id=Notes%20to%20Condensed%20Consolidated%20Financial%20Statements) The notes detail accounting policies, financial position, and significant collaboration agreements, confirming sufficient cash for the next twelve months despite an accumulated deficit - As of June 30, 2022, the company had an accumulated deficit of **$793.6 million** and cash and cash equivalents of **$508.8 million**[33](index=33&type=chunk) - Management believes the company's cash and cash equivalents as of June 30, 2022, are sufficient to meet its obligations for at least the next twelve months[34](index=34&type=chunk) - The company has significant collaboration agreements with Roche, Bristol Myers Squibb (BMS), and is entitled to potential milestone payments from Novo Nordisk[31](index=31&type=chunk) [Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations](index=29&type=section&id=Item%202.%20Management%27s%20Discussion%20and%20Analysis%20of%20Financial%20Condition%20and%20Results%20of%20Operations) Management discusses a 98% revenue decrease in Q2 2022 due to a non-recurring milestone, increased operating expenses, and the sufficiency of $508.8 million in cash for future operations [Overview](index=29&type=section&id=Overview) Prothena is a late-stage clinical biotechnology company focused on neurodegenerative and rare amyloid diseases, with wholly-owned and partnered programs in its pipeline - Birtamimab is in a confirmatory **Phase 3 AFFIRM-AL study** for AL amyloidosis under a Special Protocol Assessment (SPA) with the FDA[173](index=173&type=chunk) - Prasinezumab, partnered with Roche, is being evaluated in a **Phase 2b PADOVA study** for early Parkinson's disease[177](index=177&type=chunk) - The company's Alzheimer's portfolio includes PRX012 (anti-Aβ antibody), with an IND cleared in March 2022, and PRX005 (anti-tau antibody), partnered with Bristol Myers Squibb[184](index=184&type=chunk)[190](index=190&type=chunk) [Results of Operations](index=33&type=section&id=Results%20of%20Operations) Total revenue for Q2 2022 decreased by 98% to $1.3 million due to a non-recurring milestone, while R&D expenses increased by 50% to $31.6 million Revenue Comparison (in thousands) | Period | Q2 2022 | Q2 2021 | H1 2022 | H1 2021 | | :--- | :--- | :--- | :--- | :--- | | Collaboration revenue | $1,312 | $60,071 | $2,415 | $60,181 | | Total revenue | $1,312 | $60,071 | $2,465 | $60,231 | Operating Expense Comparison (in thousands) | Period | Q2 2022 | Q2 2021 | H1 2022 | H1 2021 | | :--- | :--- | :--- | :--- | :--- | | Research and development | $31,569 | $21,090 | $58,831 | $42,234 | | General and administrative | $12,952 | $11,032 | $24,787 | $22,157 | | Total operating expenses | $44,521 | $32,122 | $83,618 | $64,391 | - The increase in R&D expenses for Q2 2022 was primarily due to higher personnel costs, increased clinical trial expenses for PRX012 and birtamimab, and higher manufacturing costs for birtamimab, PRX019, and PRX123 programs[207](index=207&type=chunk) [Liquidity and Capital Resources](index=36&type=section&id=Liquidity%20and%20Capital%20Resources) Working capital decreased by $70.2 million to $481.2 million, with $508.8 million in cash deemed sufficient for the next twelve months, despite $72.7 million net cash used in operations Key Liquidity Metrics (in thousands) | Metric | June 30, 2022 | December 31, 2021 | | :--- | :--- | :--- | | Working capital | $481,187 | $551,357 | | Cash and cash equivalents | $508,795 | $579,094 | - Net cash used in operating activities was **$72.7 million** for the six months ended June 30, 2022, compared to net cash provided by operating activities of **$3.0 million** in the prior year period[222](index=222&type=chunk)[223](index=223&type=chunk) - The company expects full year 2022 net cash used in operating and investing activities to be approximately **$120 million to $132 million**[232](index=232&type=chunk) [Item 3. Quantitative and Qualitative Disclosures About Market Risk](index=38&type=section&id=Item%203.%20Quantitative%20and%20Qualitative%20Disclosures%20About%20Market%20Risk) The company's market risks are minimal, primarily related to foreign currency exposure in Euros, interest rate fluctuations on money market funds, and credit risk managed through high-quality financial institutions - The company's business is primarily conducted in U.S. dollars, with some foreign currency exposure through agreements denominated in Euros and other currencies[233](index=233&type=chunk) - Interest rate risk is limited as cash equivalents are held in money market funds, where interest income fluctuates with short-term market conditions[234](index=234&type=chunk) - Credit risk is managed by placing cash with high-credit-quality financial institutions and limiting exposure per institution[236](index=236&type=chunk) [Item 4. Controls and Procedures](index=39&type=section&id=Item%204.%20Controls%20and%20Procedures) Management concluded that disclosure controls and procedures were effective as of June 30, 2022, with no material changes to internal control over financial reporting during the quarter - The CEO and CFO concluded that as of June 30, 2022, the company's disclosure controls and procedures were effective to provide reasonable assurance of timely information recording, processing, and reporting[237](index=237&type=chunk) - No changes in internal control over financial reporting occurred during the second fiscal quarter that materially affected, or are reasonably likely to materially affect, internal controls[238](index=238&type=chunk) PART II. OTHER INFORMATION [Item 1. Legal Proceedings](index=40&type=section&id=Item%201.%20Legal%20Proceedings) The company is not currently involved in any material legal proceedings - The company is not currently a party to any material legal proceedings[242](index=242&type=chunk) [Item 1A. Risk Factors](index=40&type=section&id=Item%201A.%20Risk%20Factors) The company faces significant risks including a history of losses, need for capital, COVID-19 impacts, R&D program dependence, reliance on partners, regulatory challenges, and intellectual property protection - The company anticipates incurring losses for the foreseeable future and may never achieve profitability, with an accumulated deficit of **$793.6 million** as of June 30, 2022[244](index=244&type=chunk) - The COVID-19 pandemic has adversely affected business, including delaying clinical trial site initiations for the Phase 3 birtamimab trial, and could continue to disrupt clinical development programs[252](index=252&type=chunk) - The company's success is highly dependent on its research programs and collaborations with Roche and BMS, which are subject to risks such as partners not committing sufficient resources or terminating agreements[269](index=269&type=chunk)[275](index=275&type=chunk) - The company relies on third parties for conducting clinical trials and for all manufacturing of its drug candidates, creating risks related to performance, compliance, and supply chain continuity[352](index=352&type=chunk)[357](index=357&type=chunk) [Item 2. Unregistered Sales of Equity Securities and Use of Proceeds](index=73&type=section&id=Item%202.%20Unregistered%20Sales%20of%20Equity%20Securities%20and%20Use%20of%20Proceeds) There were no unregistered sales of equity securities during the reporting period - None[432](index=432&type=chunk) [Item 3. Defaults Upon Senior Securities](index=73&type=section&id=Item%203.%20Defaults%20Upon%20Senior%20Securities) There were no defaults upon senior securities during the reporting period - None[432](index=432&type=chunk) [Item 4. Mine Safety Disclosures](index=73&type=section&id=Item%204.%20Mine%20Safety%20Disclosures) This item is not applicable to the company's operations - Not Applicable[434](index=434&type=chunk) [Item 5. Other Information](index=74&type=section&id=Item%205.%20Other%20Information) No other material information is reported for the period - None[435](index=435&type=chunk) [Item 6. Exhibits](index=75&type=section&id=Item%206.%20Exhibits) This section lists filed exhibits, including CEO and CFO certifications and XBRL data files - Exhibits filed include CEO and CFO certifications pursuant to Sarbanes-Oxley Act Sections 302 and 906, and XBRL interactive data files[437](index=437&type=chunk)

PART I. FINANCIAL INFORMATION [Financial Statements](index=6&type=section&id=Item%201.%20Financial%20Statements) Prothena reported a net loss of $36.3 million in Q1 2022, with total assets decreasing to $581.4 million primarily due to reduced cash and increased R&D expenses [Condensed Consolidated Balance Sheets](index=6&type=section&id=Condensed%20Consolidated%20Balance%20Sheets) Total assets decreased to $581.4 million as of March 31, 2022, primarily due to reduced cash and cash equivalents Condensed Consolidated Balance Sheet Highlights (in thousands) | Balance Sheet Item | March 31, 2022 | December 31, 2021 | | :--- | :--- | :--- | | Cash and cash equivalents | $542,994 | $579,094 | | Total current assets | $555,620 | $584,809 | | Total assets | $581,412 | $609,366 | | Total current liabilities | $36,496 | $33,452 | | Total liabilities | $142,525 | $143,324 | | Total shareholders' equity | $438,887 | $466,042 | [Condensed Consolidated Statements of Operations](index=7&type=section&id=Condensed%20Consolidated%20Statements%20of%20Operations) Q1 2022 total revenue increased to $1.2 million, operating expenses rose to $39.1 million, resulting in a net loss of $36.3 million Q1 2022 vs Q1 2021 Statement of Operations (in thousands, except per share data) | Metric | Q1 2022 | Q1 2021 | | :--- | :--- | :--- | | Total revenue | $1,153 | $160 | | Research and development | $27,262 | $21,144 | | General and administrative | $11,835 | $11,125 | | Total operating expenses | $39,097 | $32,269 | | Loss from operations | ($37,944) | ($32,109) | | Net loss | ($36,290) | ($36,735) | | Basic and diluted net loss per share | ($0.78) | ($0.91) | [Condensed Consolidated Statements of Cash Flows](index=8&type=section&id=Condensed%20Consolidated%20Statements%20of%20Cash%20Flows) Net cash used in operating activities increased to $37.4 million in Q1 2022, leading to a $36.1 million net decrease in cash Q1 2022 vs Q1 2021 Cash Flow Summary (in thousands) | Cash Flow Activity | Q1 2022 | Q1 2021 | | :--- | :--- | :--- | | Net cash used in operating activities | ($37,415) | ($33,666) | | Net cash used in investing activities | ($22) | ($48) | | Net cash provided by financing activities | $1,337 | $81,327 | | Net (decrease) increase in cash | ($36,100) | $47,613 | [Notes to Condensed Consolidated Financial Statements](index=11&type=section&id=Notes%20to%20Condensed%20Consolidated%20Financial%20Statements) Notes detail accounting policies, collaboration agreements, and commitments, with $543.0 million cash deemed sufficient for 12 months - The company believes its cash and cash equivalents of **$543.0 million** as of March 31, 2022, are sufficient to meet its obligations for at least the next twelve months[34](index=34&type=chunk)[35](index=35&type=chunk) - As of March 31, 2022, the company had non-cancelable purchase commitments of **$16.8 million** and contractual obligations under license agreements of **$0.4 million**[69](index=69&type=chunk) - Share-based compensation expense was **$7.7 million** for Q1 2022, up from **$6.2 million** in Q1 2021. The total unearned share-based compensation to be expensed through 2026 is estimated at **$83.6 million**[156](index=156&type=chunk)[158](index=158&type=chunk) - The company recorded an income tax benefit of **$1.7 million** in Q1 2022, compared to a provision of **$4.7 million** in Q1 2021, primarily due to an increase in deferred tax assets related to Section 174 R&D Capitalization requirements[161](index=161&type=chunk)[213](index=213&type=chunk) [Management's Discussion and Analysis of Financial Condition and Results of Operations (MD&A)](index=29&type=section&id=Item%202.%20Management%27s%20Discussion%20and%20Analysis%20of%20Financial%20Condition%20and%20Results%20of%20Operations) MD&A highlights a 29% increase in R&D expenses to $27.3 million in Q1 2022, with $543.0 million cash deemed sufficient for 12 months [Overview of Business and Pipeline](index=29&type=section&id=Overview%20of%20Business%20and%20Pipeline) Prothena, a late-stage biotech, focuses on neurodegenerative and amyloid diseases with wholly-owned and partnered clinical programs - Birtamimab is in a confirmatory **Phase 3 AFFIRM-AL study** for Mayo Stage IV AL amyloidosis patients, under a Special Protocol Assessment (SPA) with the FDA[173](index=173&type=chunk) - Prasinezumab, partnered with Roche for Parkinson's disease, is being evaluated in a **Phase 2b PADOVA study**[177](index=177&type=chunk) - PRX012, a next-generation antibody for Alzheimer's disease, received FDA clearance for its IND in March 2022, initiating a **Phase 1 study**, and was granted Fast Track designation in April 2022[189](index=189&type=chunk) - PRX005, an anti-tau antibody for Alzheimer's, is part of a collaboration with Bristol Myers Squibb (BMS). BMS exercised its U.S. license option in June 2021 for an **$80 million payment**, and a **Phase 1 study** is ongoing[184](index=184&type=chunk)[185](index=185&type=chunk) [Results of Operations](index=33&type=section&id=Results%20of%20Operations) Q1 2022 total revenue increased to $1.2 million, while R&D expenses rose 29% to $27.3 million due to program advancements Operating Expenses Comparison (in thousands) | Expense Category | Q1 2022 | Q1 2021 | % Change | | :--- | :--- | :--- | :--- | | Research and development | $27,262 | $21,144 | 29% | | General and administrative | $11,835 | $11,125 | 6% | | **Total operating expenses** | **$39,097** | **$32,269** | **21%** | R&D Expenses by Major Program (in thousands) | Program | Q1 2022 | Q1 2021 | | :--- | :--- | :--- | | Birtamimab (NEOD001) | $12,432 | $6,510 | | Prasinezumab (PRX002/RG7935) | $82 | $4,876 | | PRX005 | $3,048 | $2,602 | | Other R&D | $11,536 | $5,687 | - The increase in R&D expenses was primarily due to higher manufacturing costs for the birtamimab program, increased personnel expenses, and higher clinical trial costs for the PRX012, birtamimab, and PRX005 programs[205](index=205&type=chunk) - The decrease in prasinezumab program costs was a result of the cost-share opt-out exercised in May 2021 with Roche[205](index=205&type=chunk) [Liquidity and Capital Resources](index=36&type=section&id=Liquidity%20and%20Capital%20Resources) Working capital decreased to $519.1 million, with $543.0 million cash deemed sufficient for 12 months, though future capital needs are anticipated Key Liquidity Metrics (in thousands) | Metric | March 31, 2022 | December 31, 2021 | | :--- | :--- | :--- | | Working capital | $519,124 | $551,357 | | Cash and cash equivalents | $542,994 | $579,094 | - The company believes its existing cash and cash equivalents are sufficient to meet obligations for at least the next twelve months[216](index=216&type=chunk) - As of March 31, 2022, the company had contractual obligations totaling **$28.6 million**, including **$11.4 million** in operating leases and **$16.8 million** in purchase obligations[228](index=228&type=chunk)[231](index=231&type=chunk) [Quantitative and Qualitative Disclosures About Market Risk](index=38&type=section&id=Item%203.%20Quantitative%20and%20Qualitative%20Disclosures%20About%20Market%20Risk) The company's primary market risks include foreign currency, interest rate, and credit risks, all managed with minimal impact in Q1 2022 - Foreign currency risk arises from agreements with contract manufacturers denominated in Euros and other currencies, resulting in a net loss of approximately **$70,000** in Q1 2022[232](index=232&type=chunk) - Interest rate risk is considered minimal as cash equivalents are held in money market funds, where interest income fluctuates with prevailing rates[233](index=233&type=chunk) - Credit risk is managed by placing cash with high-credit-quality financial institutions and limiting exposure, although deposits may exceed insured amounts[235](index=235&type=chunk) [Controls and Procedures](index=38&type=section&id=Item%204.%20Controls%20and%20Procedures) Management concluded that disclosure controls and procedures were effective as of March 31, 2022, with no material changes to internal controls - The CEO and CFO concluded that as of March 31, 2022, the company's disclosure controls and procedures were effective to provide reasonable assurance that required information is recorded, processed, summarized, and reported in a timely manner[236](index=236&type=chunk)[237](index=237&type=chunk) - No material changes to the company's internal control over financial reporting were identified during the first fiscal quarter ended March 31, 2022[238](index=238&type=chunk) PART II. OTHER INFORMATION [Legal Proceedings](index=40&type=section&id=Item%201.%20Legal%20Proceedings) The company is not currently a party to any material legal proceedings, though routine litigation may occur - Prothena is not currently a party to any material legal proceedings[243](index=243&type=chunk) [Risk Factors](index=40&type=page&id=Item%201A.%20Risk%20Factors) The company outlines significant risks including financial sustainability, drug development uncertainty, reliance on third parties, and intellectual property challenges [Risks Relating to Financial Position and Business](index=40&type=section&id=Risks%20Relating%20to%20Financial%20Position%20and%20Business) The company faces risks from anticipated losses, the need for additional capital, potential COVID-19 disruptions, and challenges in retaining personnel - The company expects to incur substantial losses for the foreseeable future and may never sustain profitability[245](index=245&type=chunk) - Additional capital will be required to fund operations; if unavailable, the company may have to delay or terminate clinical trials or cease operations[246](index=246&type=chunk)[252](index=252&type=chunk) - The COVID-19 pandemic has already disrupted clinical trials and could materially adversely affect liquidity, operations, and development programs[253](index=253&type=chunk) [Risks Related to Discovery, Development, and Regulatory Approval](index=45&type=section&id=Risks%20Related%20to%20Discovery%2C%20Development%2C%20and%20Regulatory%20Approval) Success depends on R&D programs prone to failure, with clinical trials facing delays and an unpredictable, costly regulatory approval process - The company's success depends on its ability to discover, develop, obtain regulatory approval for, and commercialize its drug candidates, which are in various stages of development and face significant risks of failure[270](index=270&type=chunk) - Clinical trials can be delayed, suspended, or terminated due to factors like slow enrollment, insufficient drug supply, unexpected side effects, or failure to meet endpoints[282](index=282&type=chunk)[285](index=285&type=chunk) - Although an SPA agreement is in place with the FDA for the Phase 3 AFFIRM-AL trial of birtamimab, this does not guarantee regulatory approval, as the FDA can revoke or alter the agreement under certain circumstances[296](index=296&type=chunk)[298](index=298&type=chunk) [Risks Related to Commercialization](index=51&type=section&id=Risks%20Related%20to%20Commercialization) Approved drug candidates may lack market acceptance, success depends on collaborations, and reimbursement uncertainty and intense competition pose risks - Approved products may not gain market acceptance among physicians, payers, and patients, which would limit revenues[308](index=308&type=chunk) - The success of prasinezumab is highly dependent on the collaboration with Roche, which has significant control over development and commercialization and can terminate the agreement with notice[312](index=312&type=chunk)[314](index=314&type=chunk) - Sales will depend on the availability of reimbursement from third-party payers, who are increasingly focused on cost containment, creating uncertainty around coverage and pricing[326](index=326&type=chunk)[327](index=327&type=chunk) [Risks Related to Dependence on Third Parties](index=58&type=section&id=Risks%20Related%20to%20Dependence%20on%20Third%20Parties) Prothena relies heavily on third-party CROs for clinical trials and manufacturers for supplies, posing risks if they fail to perform or comply with regulations - The company relies on third parties like CROs to conduct clinical trials and may be delayed if these parties do not perform satisfactorily or meet deadlines[353](index=353&type=chunk) - Prothena has no manufacturing capacity and depends on third-party manufacturers for all nonclinical and clinical trial supplies. Any failure by these manufacturers could delay or suspend production and development[358](index=358&type=chunk)[361](index=361&type=chunk) [Risks Related to Intellectual Property](index=61&type=section&id=Risks%20Related%20to%20Intellectual%20Property) Success depends on uncertain patent enforcement, with risks of costly litigation, difficulty protecting trade secrets, and potential license terminations - The ability to obtain, maintain, and enforce patents is uncertain and involves complex legal and scientific questions; issued patents may not provide sufficient protection[368](index=368&type=chunk) - The company may face expensive and time-consuming litigation regarding patents and proprietary rights, which could cause delays and harm its ability to operate[392](index=392&type=chunk) - The company relies on trade secrets and confidentiality agreements, which may not effectively prevent disclosure of proprietary information[402](index=402&type=chunk) [Risks Related to Our Ordinary Shares](index=69&type=section&id=Risks%20Related%20to%20Our%20Ordinary%20Shares) Ordinary share price may fluctuate due to clinical results and market conditions, with dilution risk and complexities from Irish incorporation and stamp duty - The market price of ordinary shares is subject to wide fluctuation based on clinical trial results, regulatory news, competitor actions, and general market conditions[407](index=407&type=chunk) - Being an Irish-incorporated company means it is governed by the Irish Companies Act, which differs from U.S. corporate law and may offer less protection to shareholders in areas like director duties and shareholder lawsuits[419](index=419&type=chunk)[421](index=421&type=chunk) - Transfers of ordinary shares may be subject to Irish stamp duty (currently **1%**), which could adversely affect the share price[426](index=426&type=chunk) [Unregistered Sales of Equity Securities and Use of Proceeds](index=73&type=section&id=Item%202.%20Unregistered%20Sales%20of%20Equity%20Securities%20and%20Use%20of%20Proceeds) The company reported no unregistered sales of equity securities during the period - None[434](index=434&type=chunk) [Other Information](index=74&type=section&id=Item%205.%20Other%20Information) The company reported no other information for this item - None[437](index=437&type=chunk) [Exhibits](index=75&type=section&id=Item%206.%20Exhibits) This section lists exhibits filed with the Form 10-Q, including CEO/CFO certifications and XBRL data files - The exhibits filed include certifications from the Principal Executive Officer and Principal Financial Officer as required by the Sarbanes-Oxley Act of 2002, along with XBRL interactive data files[439](index=439&type=chunk)

Corporate Strategy and Pipeline - Prothena aims to develop best-in-class therapeutics to slow, stop, or prevent proteinopathies by targeting proteins with the greatest effect on disease[12] - The company plans to file five potential new Investigational New Drug (IND) applications from its Biology-Directed Engine in the next five years[13] - Prothena is leveraging its rare disease portfolio to support a transition into a fully-integrated commercial biotech[13] Alzheimer's Disease Programs - Prothena's PRX012, an anti-Aβ subcutaneous product candidate, has 10X greater binding potency than aducanumab and is expected to have an IND filing in 1Q22[10, 46] - Topline Phase 1 data for PRX005, a tau MTBR-specific antibody being developed in collaboration with Bristol Myers Squibb, is expected in 2022[21, 55] - A dual Aβ/Tau vaccine for potential treatment and prevention of Alzheimer's disease is expected to have an IND filing in 2023, with preclinical data presented at AD/PD in March 1Q22[21] Amyloidosis Programs - Birtamimab, for AL amyloidosis, is in a confirmatory Phase 3 AFFIRM-AL study with topline data expected in 2024, targeting all-cause mortality at p≤0.10 under a Special Protocol Assessment (SPA) agreement with the FDA[18, 73, 83] - Novo Nordisk is expected to initiate a Phase 2 trial of PRX004 in patients with ATTR cardiomyopathy in 1H 2022; Prothena is eligible to receive up to $1.23 billion in total consideration from Novo Nordisk[14, 21, 88] Parkinson's Disease Program - Prasinezumab, in partnership with Roche, is in a Phase 2b PADOVA study with results expected in 2024[21, 94] - The PASADENA Phase 2 study showed a 35% reduction in decline in motor function vs placebo at one year on MDS-UPDRS Part III[97] Financial Position - Prothena had a strong cash position of $580 million as of December 31, 2021[103] - The company has potential payments of up to $365 million over the next 5 years (2022-2026) from collaborations[102]

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ______________________________________ FORM 10-K ______________________________________ (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the year ended December 31, 2021 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-35676 ______________________________________ PROTHENA CORPORATIO ...

Prothena Corporation plc (NASDAQ:PRTA) Q4 2021 Earnings Conference Call February 17, 2022 4:30 PM ET Company Participants Jennifer Zibuda - Director-Investor Relations & Communications Gene Kinney - President & Chief Executive Officer Tran Nguyen - Chief Financial Officer & Chief Strategy Officer Hideki Garren - Chief Medical Officer Wagner Zago - Chief Scientific Officer Conference Call Participants Charles Duncan - Cantor Fitzgerald Michael Yee - Jefferies Neena Bitritto-Garg - Citi Jay Olson - Oppenheime ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ______________________________________ FORM 10-Q _____________________________________ (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30,2021 Or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission file number: 001-35676 ______________________________________ PROTHENA CORPORATION PUBLIC LIMITED ...