Q4 2025 Prothena Corp Plc Earnings Call

February 19, 2026

Operator: Good day, ladies and gentlemen, and welcome to the Prothena Biosciences Q4 and full year 2025 financial results conference call. My name is Jeannie, and I will be your coordinator for today. At this time, all participants are in listen-only mode. We will be facilitating a question and answer session at the end of today's call. If at any time during the call you require assistance, please press star followed by zero, and a coordinator will be happy to assist you. I would now like to turn the presentation over to Mark Johnson, Vice President and Head of Investor Relations at Prothena. Please proceed.

Speaker #1: Good day, ladies and gentlemen, and welcome to the Prothena Bioscience's fourth quarter and full year 2025 financial results conference call. My name is Jeannie, and I will be your coordinator for today.

Speaker #1: At this time, all participants are in a listen-only mode. We will be facilitating a question-and-answer session at the end of today's call. If, at any time during the call, you require assistance, please press star followed by zero, and a coordinator will be happy to assist you.

Speaker #1: I would now like to turn the presentation over to Mark Johnson, Vice President and Head of Investor Relations at Prothena. Please proceed.

Mark Johnson: Thank you, operator. Good afternoon, everyone, and welcome to today's call to review Prothena's business progress, fourth quarter and full year 2025 financial results, and 2026 financial guidance. Please review the press release we issued earlier today, which is available on our website at prothena.com and is also attached to a Form 8-K filed today with the SEC. In addition, we are using supplemental slides, which are available on our investors website, events, and presentation section. On today's call, Dr. Gene Kinney, our President and Executive Officer, will provide opening remarks, including an overview on Prothena's corporate strategy. Chad Swanson, our Chief Development Officer, will provide an update on our ongoing partnered clinical programs. Phil Bhardwaj, our Vice President and Head of Discovery Research, will provide an update on our active preclinical programs.

Speaker #2: Thank you, Operator. Good afternoon, everyone, and welcome to today's call to review Prothena's business progress, fourth quarter and full year 2025 financial results, and 2026 financial guidance.

Speaker #2: Please review the press release we issued earlier today, which is available on our website at prothena.com, and is also attached to a Form 8K filed today with the SEC.

Speaker #2: In addition, we are using supplemental slides, which are available on our investors' website in the events and presentations section. On today's call, Dr. Gene Kenny, our President and Executive Officer, will provide opening remarks, including an overview of Prothena's corporate strategy.

Speaker #2: Chad Swanson, our Chief Development Officer, will provide an update on our ongoing partnered clinical programs. Then Phil Dolan, our Vice President and Head of Discovery Research, will provide an update on our active preclinical programs.

Speaker #2: Tron Nguyen, our Chief Strategy Officer and Chief Financial Officer, will then discuss our 2025 financial results and 2026 financial guidance before turning it back to Gene for closing remarks.

Mark Johnson: Tran Nguyen, our Chief Strategy Officer and Chief Financial Officer, will then discuss our 2025 financial results and 2026 financial guidance before turning it back to Gene for closing remarks, at which point we will open up the call for a Q&A session. Brandon Smith, our Chief Operating Officer, will also be available during the Q&A session. Before we begin, I would like to remind you that during today's presentation, we will be making forward-looking statements that are subject to certain risks, uncertainties, and other factors that could cause actual results to differ materially from those referred to in any of the forward-looking statements.

Speaker #2: At which point, we will open up the call for a Q&A session. Brandon Smith, our Chief Operating Officer, will also be available during the Q&A session.

Speaker #2: Before we begin, I would like to remind you that during today's presentation, we will be making forward-looking statements that are subject to certain risks, uncertainties, and other factors that could cause actual results to differ materially from those referred to in any of the forward-looking statements.

Speaker #2: For discussion of these risks and uncertainties associated with our forward-looking statements, please see our press release issued today, as well as our most recent filings with the SEC and our annual report on Form 10K to be filed with the SEC for our fiscal year 2025.

Mark Johnson: For a discussion of these risks and uncertainties associated with our forward-looking statements, please see our press release issued today, as well as our most recent filings with the SEC, and our annual report on Form 10-K to be filed with the SEC for our fiscal year 2025. We disclaim any obligation to update our forward-looking statements. With that, I'd like to turn the call over to Gene.

Speaker #2: We disclaim any obligation to update our forward-looking statements. With that, I'd like to turn the call over to Gene.

Speaker #3: Thank you, Mark. And thank you all for joining us today. Let's begin on Slide 5. In 2025, we saw significant progress with our clinical pipeline, where two of our partnered programs, PrecedesMab and Parametug, advanced into Phase 3 clinical trials.

Gene Kinney: Thank you, Mark, and thank you all for joining us today. Let's begin on slide five. In 2025, we saw significant progress with our clinical pipeline, where two of our partner programs, prasinezumab and coramitug, advanced into phase 3 clinical trials. Roche advanced prasinezumab into the phase 3 Pariseo trial, evaluating 900 participants with early Parkinson's disease. This decision was informed by results from two phase 2 clinical trials that both demonstrated consistent slowing of disease progression. Novo Nordisk advanced coramitug into the phase 3 Cleopatra trial, evaluating 1,280 patients with amyloid transthyretin cardiomyopathy, or ATTR-CM. This decision was informed by results from their phase 2 trial, demonstrating positive NT-proBNP and echocardiogram changes, as well as directional observation of benefit in the six-minute walk test....

Speaker #3: Roche advanced PrecedesMab into the Phase 3 PRECO trial, evaluating 900 participants with early Parkinson's disease. This decision was informed by results from two Phase 2 clinical trials that both demonstrated consistent slowing of disease progression.

Speaker #3: Novo Nordisk advanced Parametug into the Phase 3 Cleopatra trial. Evaluating 1,280 patients with amyloid transdiuretic cardiomyopathy, or ATTRCM. This decision was informed by results from their Phase 2 trial demonstrating positive NT-proBNP and echocardiogram changes, as well as directional observation of benefit in the six-minute walk test.

Speaker #3: Our collaborations with Bristol-Myers Squibb also progressed in 2025, with several important advancements, including the Phase 2 target COW1 clinical trial evaluating BMS-986446 in early Alzheimer's disease, which was fully enrolled in 2025, with completion expected in the first half of 2027.

Gene Kinney: Our collaborations with Bristol Myers Squibb also progressed in 2025, with several important advancements, including the Phase 2 Target TAL-1 clinical trial, evaluating BMS-986446 in early Alzheimer's disease, which was fully enrolled in 2025, with completion expected in the first half of 2027. Bristol Myers Squibb also completed a Phase 1 study evaluating a subcutaneous formulation of BMS-986446 in 2025. And BMS-986446 obtained Fast Track designation from the US FDA for the treatment of Alzheimer's disease. And finally, we are conducting a Phase 1 trial for PRX019, which is on track for completion in 2026. We also shared important updates from our wholly-owned preclinical portfolio in 2025.

Speaker #3: Bristol-Myers Squibb also completed a Phase 1 study evaluating a subcutaneous formulation of BMS-986446 in 2025. And BMS-986446 obtained fast-track designation from the US FDA for the treatment of Alzheimer's disease.

Speaker #3: And finally, we are conducting a Phase 1 trial for PRX19, which is on track for completion in 2026. We also shared important updates from our wholly owned preclinical portfolio in 2025.

Speaker #3: In the fourth quarter, we introduced our CYTOPE technology with presentations of our TDP-43 CYTOPE program for ALS at two scientific congresses. At a high level, these data demonstrated that our CYTOPE technology has the potential to enable precise targeting of intracellular disease pathways.

Gene Kinney: In Q4, we introduced our Cytope technology with presentations of our TDP-43 Cytope program for ALS at two scientific congresses. At a high level, these data demonstrated that our Cytope technology has the potential to enable precise targeting of intracellular disease pathways. We also reported results from our phase 1 ASCENT clinical program, evaluating PRX012 in patients with early Alzheimer's disease. The results helped to elucidate the profile of this once-monthly subcutaneous anti-Aβ antibody. Based on significant scientific advances over the last several years, we believe we can further improve this profile with the addition of transferrin receptor technology and are actively advancing a PRX012 TfR program in preclinical development. Turning to slide 6, we have several key 2026 priorities that we believe meaningfully contribute to long-term value creation.

Speaker #3: We also reported results from our Phase 1 Ascent clinical program, evaluating PRX12 in patients with early Alzheimer's disease. The results helped to elucidate the profile of this once-monthly subcutaneous anti-A beta antibody.

Speaker #3: Based on significant scientific advances over the last several years, we believe we can further improve this profile with the addition of transferrin receptor technology and are actively advancing a PRX12 transferrin program in preclinical development.

Speaker #3: Turning to Slide 6, we have several key 2026 priorities that we believe meaningfully contribute to long-term value creation. The first is to ensure we are best positioned to capture value embedded in our clinical partnerships.

Gene Kinney: The first is to ensure we are best positioned to capture value embedded in our clinical partnerships. As a reminder, all of our partnerships with large pharma companies are programs that originated from Prothena's R&D engine. This year, we have the potential to earn up to $105 million in aggregate clinical milestone payments if coramitug achieves a pre-specified enrollment target in its ongoing phase 3 trial and if BMS decides to advance PRX019 into phase 2 clinical development. In addition, we have now received all the necessary approvals from our extraordinary general meeting of shareholders and confirmed by the Irish High Court to support a share redemption program in 2026. Finally, we continue to advance our knowledge and understanding of our preclinical portfolio to support our business development team as they explore research collaborations and licensing agreements.

Speaker #3: As a reminder, all of our partnerships with large pharma companies are programs that originated from Prothena's R&D engine. This year, we have the potential to earn up to $105 million in aggregate clinical milestone payments, if Parametug achieves a pre-specified enrollment target in its ongoing Phase 3 trial, and if BMS decides to advance PRX19 into Phase 2 clinical development.

Speaker #3: In addition, we have now received all the necessary approvals from our extraordinary general meeting of shareholders and confirmed by the Irish High Court to support a share redemption program in 2026.

Speaker #3: Finally, we continue to advance our knowledge and understanding of our preclinical portfolio to support our business development team as they explore research collaborations and licensing agreements.

Speaker #3: For example, we are engaged in a research collaboration with a large pharmaceutical company that explores multiple approaches for applying our CYTOPE technology to advance and elucidate intracellular targeting.

Gene Kinney: For example, we are engaged in a research collaboration with a large pharmaceutical company that explores multiple approaches for applying our Cytope technology to advance and elucidate intracellular targeting. We look forward to establishing additional research collaborations, which may lead to future licensing deals. Our strategic priorities are supported by our $308.4 million cash and restricted cash balance as of year-end 2025, and our prudent capital utilization to ensure that we are well-positioned to receive future potential economics from our partner programs. Let's move to slide seven to review our upcoming catalysts from our partner portfolio. Looking ahead, we have two potential milestones in 2026 from coramitug and PRX019, which could be worth up to $105 million.

Speaker #3: We look forward to establishing additional research collaborations, which may lead to future licensing deals. Our strategic priorities are supported by our $308.4 million cash and restricted cash balance as of year-end 2025, and our prudent capital utilization to ensure that we are well positioned to receive future potential economics from our partnered programs.

Speaker #3: Let's move to Slide 7 to review our upcoming catalysts from our partnered portfolio. Looking ahead, we have two potential milestones in 2026 from Parametug and PRX19, which could be worth up to $105 million.

Speaker #3: In the first half of 2027, we expect Bristol-Myers Squibb to complete their Phase 2 target COW1 trial for BMS-986446, and in 2029, we expect primary completions from the two Phase 3 trials evaluating Roche's PrecedesMab and Novo Nordisk's Parametug.

Gene Kinney: In the first half of 2027, we expect Bristol-Myers Squibb to complete their Phase 2 Target TAL-one trial for BMS-986446. In 2029, we expect primary completions from the two Phase 3 trials evaluating Roche's prasinezumab and Novo Nordisk's coramitug. In total, when you look at our four partner clinical programs, they have the potential in aggregate to deliver up to approximately $3 billion in future milestone payments, which is in addition to any royalties. With that, I'll now turn the call over to Chad to discuss our partner programs in more detail.

Speaker #3: In total, when you look at our four partnered clinical programs, they have the potential, in aggregate, to deliver up to approximately $3 billion in future milestone payments, which is in addition to any royalties.

Speaker #3: With that, I'll now turn the call over to Chad to discuss our partnered programs in more detail.

Speaker #4: Thanks, Gene. To start on Slide 9, PrecedesMab is a humanized IgG1 monoclonal antibody designed to selectively bind aggregated forms of alpha-synuclein to reduce neuronal toxicity and slow disease progression of Parkinson's disease.

Chad Swanson: Thanks, Gene. Let's start on slide nine. Prasinezumab is a humanized IgG1 monoclonal antibody designed to selectively bind aggregated forms of alpha-synuclein to reduce neurotoxicity and slow disease progression of Parkinson's disease by blocking further accumulation and propagation of these toxic aggregates. Based on the consistent results from two phase 2 clinical trials, PADOVA and PASADENA, and their open-label extensions, our partner, Roche, made the decision to advance prasinezumab to phase 3, bringing this potential first disease-modifying therapy one step closer to patients. In fact, Roche made this decision based on a number of important questions. First, is there an unmet need? Yes, there are over 10 million Parkinson's patients globally, and it is the fastest growing neurodegenerative disease with no approved disease-modifying therapies to slow progression. Second, does it address a foundational target? Yes.

Speaker #4: By blocking further accumulation and propagation of these toxic aggregates. Based on the consistent results from two Phase 2 clinical trials, Adobe and Pasadena, and their open-label extensions, our partner Roche made the decision to advance PrecedesMab to Phase 3.

Speaker #4: Bringing this potential first disease-modifying therapy one step closer to patients. In fact, Roche made this decision based on a number of important questions. First, is there an unmet need?

Speaker #4: Yes, there are over 10 million participants globally, and it is the fastest-growing neurodegenerative disease with no approved disease-modifying therapies to slow progression. Second, does it address the foundational target?

Speaker #4: Yes, alpha-synuclein is a known biological driver of PD progression, and the clinical evidence to date demonstrates efficacy potential and supports a favorable safety and tolerability profile.

Chad Swanson: Alpha-synuclein is a known biological driver of PD progression, and the clinical evidence to date demonstrates efficacy potential and supports a favorable safety and tolerability profile. Third, is there a meaningful therapeutic differentiation? Yes. The totality of data suggests clear evidence, delayed motor progression, even on top of the standard symptomatic treatment levodopa. And finally, is there a strong commercial rationale? Yes. Roche believes prasinezumab represents a global peak sales opportunity greater than $3.5 billion. For Prothena, our deal includes up to $620 million in potential future milestone payments and sales royalties tiered to high teen percentages. In Q4 2025, Roche initiated the phase 3 PARADISO clinical trial, which will enroll approximately 900 participants with early Parkinson's disease, with primary completion expected in 2029. Moving on to slide 10.

Speaker #4: Third, is there a meaningful therapeutic differentiation? Yes, the totality of data suggests clear evidence delayed motor progression, even on top of the standard symptomatic treatment levodopa.

Speaker #4: And finally, is there a strong commercial rationale? Yes, Roche believes PrecedesMab represents a global peak sales opportunity greater than $3.5 billion. For Prothena, our deal includes up to $620 million in potential future milestone payments and sales royalties tiered to high-teen percentages.

Speaker #4: In the fourth quarter of 2025, Roche initiated the Phase 3 PARA-ISO clinical trial, which will enroll approximately 900 participants with early Parkinson's disease, with primary completion expected in 2029.

Speaker #4: Moving on to Slide 10, this is an important dataset from the Phase 2B PADOVA trial which Roche presented at ADPD 2025. Here they show progression on the MDS UPDRS Part 3 scale from baseline, which is used to measure disease progression on motor symptoms.

Chad Swanson: This is an important data set from the Phase 2b PADOVA trial, which Roche presented at ADPD 2025. Here they show progression on the MDS-UPDRS Part Three scale from baseline, which is used to measure disease progression on motor symptoms. This figure shows the results for an exploratory endpoint, looking at the subset of participants. Approximately 75% of the trial population were on stable levodopa treatment, comparing 24 months of prasinezumab treatment versus placebo. What we see is a 40% relative reduction in progression, with a nominal P value of 0.0177 on this exploratory endpoint. These were very important results as they were used to further optimize aspects of the Phase 3 PERISOF trial design. On slide 11, let's review key aspects of the Phase 3 protocol that were optimized to increase the relative probability of successful outcome. First, increased patient population.

Speaker #4: This figure shows the results for an exploratory endpoint looking at the subset of participants, approximately 75% of the trial population, who are on stable levodopa treatment, comparing 24 months of PrecedesMab treatment versus placebo.

Speaker #4: What we see is a 40% relative reduction in progression, with a nominal p-value of 0.0177 on this exploratory endpoint. These were very important results, as they were used to further optimize aspects of the Phase 3 PARA-ISO trial design.

Speaker #4: On Slide 11, let’s review key aspects of the Phase 3 protocol that were optimized to increase the relative probability of a successful outcome. First, increased patient population.

Speaker #4: The Phase 3 trial is evaluating 900 patients, whereas the Phase 2B PADOVA trial enrolled 586 patients. Second, all patients in the Phase 3 trial are required to be on stable symptomatic treatment with levodopa.

Chad Swanson: The phase 3 trial is evaluating 900 patients, whereas the phase 2b PADOVA trial enrolled 586 patients. Second, all patients in the phase 2 trial are required to be on stable symptomatic treatment with levodopa. In the prior phase 2b PADOVA trial, the approximately 75% of patients on levodopa treatment were nominally statistically significant on the primary outcome, and exploratory endpoint shown on the previous slide. Third, the duration of the phase 3 trial is a minimum of 24 months, versus 18 months in the prior phase 2b PADOVA trial. In the PADOVA trial, the patients who were on treatment for at least 24 months had greater separation from placebo on the exploratory endpoint shown on the previous slide.

Speaker #4: In the prior Phase 2B PADOVA trial, the approximately 75% of patients on levodopa treatment were nominally statistically significant on the primary outcome and the exploratory endpoint shown on the previous slide.

Speaker #4: Third, the duration of the Phase 3 trial is a minimum of 24 months versus 18 months in the prior Phase 2B PADOVA trial. In the PADOVA trial, the patients who are on treatment for at least 24 months had greater separation from placebo on the exploratory endpoint shown on the previous slide.

Speaker #4: We believe Roche will continue to communicate clinical results from its completed Phase 2 trials and ongoing open-label extensions at upcoming medical conferences. We look forward to the primary completion of the Phase 3 PARA-ISO trial, expected in 2029.

Chad Swanson: We believe Roche will continue to communicate clinical results from its completed Phase 2 trials and ongoing open-label extensions at upcoming medical conferences. We look forward to the primary completion of the Phase 3 PERISOF trial expected in 2029. Moving to coramitug on slide 12, potential first-in-class amyloid depleter antibody for the treatment of ATTR cardiomyopathy being developed by Novo Nordisk. ATTR-CM is a rare, progressive, and potentially fatal disease characterized by deposition of abnormal, non-native forms of transthyretin amyloid in vital organs. Coramitug is thought to deplete both the positive amyloid and circulating non-native TTR to prevent further deposition and to improve organ function. This mechanism of action has the potential to provide benefit for all ATTR-CM patients, even those patients currently receiving treatment with a stabilizer or silencer.

Speaker #4: Moving to Parametug on Slide 12, potential first-in-class amyloid depleter antibody for the treatment of ATDR cardiomyopathy being developed by Novo Nordisk. ATTRCM is a rare, progressive, and potentially fatal disease characterized by deposition of abnormal non-native forms of transthyroid amyloid and vital organs.

Speaker #4: Parametug is thought to deplete both the positive amyloid and circulating non-native TTR to prevent further deposition and to improve organ function. This mechanism of action has the potential to provide benefit for all ATTRCM patients even those patients currently receiving treatment with a stabilizer or silencer.

Speaker #4: Novo Nordisk completed its Phase 2 clinical trial evaluating Parametug and ATTRCM in 2025 and presented those positive results in a late-breaking session at the American Heart Association's 2025 scientific sessions with a simultaneous publication in the journal's circulation.

Chad Swanson: Novo Nordisk completed its phase 2 clinical trial evaluating coramitug in ATTR-CM in 2025 and presented those positive results in a late-breaking session at the American Heart Association's 2025 Scientific Sessions, with a simultaneous publication in the journal Circulation. The results demonstrated reductions in NT-proBNP and echocardiogram improvements suggested a cardiac remodeling, all with a favorable safety profile. It's important to note that these results were demonstrated on top of standard of care, with over 80% of patients across coramitug and placebo control arms receiving concomitant TTR stabilizers. Based on these results, Novo Nordisk initiated a phase 3 CLEOPATRA trial, which is intended to enroll approximately 1,280 ATTR-CM patients, primary completion expected in 2029.

Speaker #4: The results demonstrated reductions in NT-proBNP and echocardiogram improvements suggestive of cardiac remodeling, all with a favorable safety profile. It's important to note that these results were demonstrated on top of standard of care, with over 80% of patients across Parametug and placebo control arms receiving concomitant TTR stabilizers.

Speaker #4: Based on these results, Novo Nordisk initiated a Phase 3 Cleopatra trial, which is intended to enroll approximately 1,280 ATTRCM patients, with primary completion expected in 2029.

Chad Swanson: Based on peak sales estimates for the currently approved ATTR-CM drugs, we believe that coramitug represents a multi-billion-dollar market opportunity, allowing Prothena to potentially capture future milestone payments of up to an additional $1.13 billion. Let's review the phase 2 results on slide 13. This was a 12-month, 105-patient phase 2 trial randomized to placebo, 10 mg/kg coramitug, or 60 mg/kg coramitug. The co-primary endpoints were change from baseline versus placebo in NT-proBNP, in the six-minute walk test. The 60 mg/kg dose of coramitug resulted in a statistically significant reduction in NT-proBNP versus placebo, with a 48% difference and a P value equal to 0.0017. In addition, coramitug actually reduced NT-proBNP below baseline values in the 60 mg/kg dose.

Speaker #4: Based on peak sales estimates for the currently approved ATTRCM drug, we believe that Parametug represents a multibillion-dollar market opportunity. Allowing PROTHENA to potentially capture future milestone payments of up to an additional $1.13 billion.

Speaker #4: Let's review the Phase 2 results in Slide 13. This was a 12-month, 105-patient Phase 2 trial randomized to placebo 10 mg/kg Parametug or 60 mcg Parametug.

Speaker #4: The coprimary endpoints were changed from baseline versus placebo in NT-proBNP in the six-minute walk test. The 60 mcg dose of Parametug resulted in a statistically significant reduction in NT-proBNP versus placebo with a 48% difference and a p-value equal to 0.0017.

Speaker #4: In addition, Parametug actually reduced NT-proBNP below baseline values in the 60 mg/kg group. For the six-minute walk test, the 60 mcg Parametug group demonstrated an encouraging numerical improvement, but it was not statistically significant, likely due to small sample size and short study duration.

Chad Swanson: For the 6-minute walk test, the 60 mg/kg coramitug group demonstrated an encouraging numerical improvement, but it was not statistically significant, likely due to small sample size and short study duration. Additional analyses included a wide range of echocardiogram parameters, including measures of left and right ventricular systolic function, diastolic function, and estimated pulmonary arterial pressures. Across these measures, coramitug at 60 mg/kg was associated with improvement compared to placebo, suggesting cardiac remodeling. These results were the basis for advancing coramitug to phase 3. As we see in slide 14, the phase 3 CLEOPATRA trial is anticipated to enroll approximately 1,280 ATTR-CM patients, randomized 1:1 to coramitug plus standard of care, placebo plus standard of care. The trial is available to New York Heart Association class 1 through 4 patients, with some additional inclusion/exclusion criteria.

Speaker #4: Additional analyses included a wide range of echocardiogram parameters, including measures of left and right ventricular systolic function, diastolic function, and estimated pulmonary arterial pressures.

Speaker #4: Across these measures, Parametug at 60 mcg was associated with improvement compared to placebo suggestive of cardiac remodeling. These results form the basis for advancing Parametug to Phase 3.

Speaker #4: As we see in Slide 14, the Phase 3 CLEOPATRA trial is anticipated to enroll approximately 1,280 ATTR-CM patients, randomized one-to-one to Parametug plus standard of care or placebo plus standard of care.

Speaker #4: The trial is available to New York Heart Association Class I through IV patients, with some additional inclusion and exclusion criteria. The primary endpoint is a composite endpoint of either the number of cardiovascular deaths or recurrent cardiovascular events, such as hospitalization or an urgent heart failure visit.

Chad Swanson: The primary endpoint is a composite endpoint of either the number of cardiovascular deaths or recurrent cardiovascular events, such as hospitalization or an urgent heart failure visit. We look forward to the primary completion of the Phase 3 CLEOPATRA trial expected in 2029. Moving on. Let's now discuss BMS-986446 on slide 15. This is our potential first-in-class anti-tau antibody being developed by Bristol Myers Squibb. BMS-986446 was specifically designed to target a key epitope within the microtubule binding region, or MTBR, of tau protein implicated in the causal pathophysiology of Alzheimer's. Tau tangles, along with amyloid beta plaques, are core hallmarks of Alzheimer's pathology, and tau is strongly linked to clinical and cognitive decline. To date, BMS-986446 has completed its Phase 1 MAD and SAD trials, as well as an open-label single-dose trial to assess the subcutaneous formulation.

Speaker #4: We look forward to the primary completion of the Phase 3 Cleopatra trial expected in 2029. Moving on, let's now discuss BMS-986446 on Slide 15.

Speaker #4: This is our potential first-in-class anti-tile antibody being developed by Bristol-Myers Squibb. BMS-986446 was specifically designed to target key epitopes within the microtubule binding region or MTBR of tile, protein implicated in the causal pathophysiology of Alzheimer's.

Speaker #4: Tau tangles, along with amyloid beta plaques, are hallmarks of Alzheimer's pathology, and tau is strongly linked to clinical and cognitive decline. To date, BMS-986446 has completed its Phase 1 MAD and SAD trials, as well as an open-label single-dose trial to assess the subcutaneous formulation.

Speaker #4: In addition, BMS-986446 was granted fast-track designation by the US FDA for the treatment of Alzheimer's disease. Bristol-Myers Squibb completed enrollment in the ongoing Phase 2 target tile 1 clinical trial in approximately 310 patients with an early Alzheimer's in 2025 and we expect study completion in the first half of 2027.

Chad Swanson: In addition, BMS-986446 was granted Fast Track designation by the US FDA for the treatment of Alzheimer's disease. Bristol Myers Squibb completed enrollment in the ongoing phase 2 TARGET-TAU-1 clinical trial in approximately 310 patients with early Alzheimer's in 2025, and we expect study completion in the first half of 2027. Alzheimer's disease represents a multi-billion dollar market opportunity, and in our partnership with BMS, we have the potential to earn up to an additional $562.5 million future milestones, as well as tiered sales royalties up to high teens percentages on a weighted average basis. Slide 16 illustrates the various areas where antibodies have been developed to target tau. Tau is a large protein comprised of approximately 440 amino acids in some forms, with multiple phosphorylation sites, truncation sites, and multiple splice variants.

Speaker #4: Alzheimer's disease represents a multibillion-dollar market opportunity and in our partnership with BMS, we have the potential to earn up to an additional $562.5 million future milestones as well as tiered sales royalties up to high teens percentages on a weighted average basis.

Speaker #4: Slide 16 illustrates the various areas where antibodies have been developed to target tile. Tile is a large protein comprised of approximately 440 amino acids in some forms with multiple phosphorylation sites, truncation sites, and multiple slice variants.

Speaker #4: One of the long-standing challenges in the field has been how to best target the TIL protein in order to provide functional benefit in the context of disease.

Chad Swanson: One of the long-standing challenges in the field has been how to best target the tau protein in order to provide functional benefit in the context of disease. We took an approach called empirical epitope mapping in order to identify an antibody that delivered consistent, robust effects. This work led us to target the MTBR domain, which was the only area that satisfied our internal requirements. The field has since clarified that MTBR domain is central to fiber formation, seeding, and cell-to-cell transmission of tau pathology. MTBR tau 243 has been shown to be highly correlated with tau PET and disease progression. In preclinical studies, MTBR-targeting antibodies demonstrated blocking of internalization and spread of tau, leading to the reduction of tau pathology. Ongoing Phase 2 clinical trials, including the Phase 2 TARGET-TAU-1 trial for our partner, BMS, are underway.

Speaker #4: We took an approach called empirical epitope mapping in order to identify an antibody that delivered consistent robust effects. This work led us to target the MTBR domain, which was the only area that satisfied our internal requirements.

Speaker #4: The field has since clarified that MTBR domain is central to fibroformation, seeding, and cell-to-cell transmission of tile pathology. MTBR tile 243 has been shown to be highly correlated with tile PET and disease progression.

Speaker #4: In preclinical studies, MTBR-targeting antibodies demonstrated blocking of internalization and spread of tau, leading to the reduction of tau pathology. Ongoing Phase 2 clinical trials, including the Phase 2 Tau Target 1 trial for our partner BMS, are underway.

Speaker #4: A different anti-MTBR tile antibody recently demonstrated positive trends on biomarkers including MTBR tile 243 and tile PET in a small number of patients. Slide 17 highlights the Phase 2 target tile 1 trial design, which enrolled approximately 310 patients with early Alzheimer's disease.

Chad Swanson: A different anti-MTBR tau antibody recently demonstrated positive trends on biomarkers, including MTBR tau 243 and tau PET, in a small number of patients. Slide 17 highlights the Phase 2 TARGET-TAU-1 trial design, which enrolled approximately 310 patients with early Alzheimer's disease, randomized 4 to 3, 3 in placebo, low-dose BMS-986446, and high-dose BMS-986446 respectively. The primary endpoint is change from baseline in brain tau deposition, as measured by tau PET at 76 weeks, with secondary endpoints measuring functional and cognitive changes, including CDR-SB and iADRS. We are excited to learn the results from this, this Phase 2 trial, with primary completion expected in the first half of 2027. And finally, I'll briefly review PRX-019 on Slide 18.

Speaker #4: Randomized 4 to 3, 3, and placebo low-dose BMS-986446 and high-dose BMS-986446 respectively. The primary endpoint is changed from baseline in brain tile deposition, measured by tile PET at 76 weeks, with secondary endpoints measuring functional and cognitive changes including CDR sum of boxes and NIDRS.

Speaker #4: We are excited to learn the results from this Phase 2 trial, with primary completion expected in the first half of 2027. And finally, I'll briefly review PRX-19 on Slide 18.

Speaker #4: Per our agreement with Bristol-Myers Squibb, we are conducting the Phase 1 trial, both single-ascending and multiple doses, evaluating safety, tolerability, immunogenicity, TK, and pharmacodynamic effects.

Chad Swanson: Per our agreement with Bristol Myers Squibb, we are conducting the phase 1 trial, while single ascending in multiple doses, evaluating safety, tolerability, immunogenicity, PK, and pharmacodynamic effects. We expect to complete the trial in 2026 and are eligible for a potential milestone should BMS decide to further develop PRX019. In total, we have the potential to earn up to $617.5 million in future milestones, tiered sales royalties up to high teen percentages. With that, I'll now turn the call over to Phil Bhardwaj to discuss our wholly owned preclinical portfolio.

Speaker #4: We expect to complete the trial in 2026 and are eligible for a potential milestone should BMS decide to further develop PRX-19. In total, we have the potential to earn up to $617.5 million in future milestones and tiered sales royalties up to high teen percentages.

Speaker #4: With that, I'll now turn the call over to Phil Dolan to discuss our wholly owned preclinical portfolio.

Speaker #2: Thanks, Chad. Please turn to Slide 20 for an overview of our exciting new sites of technology. Our sites of technology is an innovative targeting technology invented by PRESENA to reach virtually any cell type and enable precise targeting of intracellular disease pathways in the brain and periphery through an endosomal uptake and escape mechanism that preserves membrane and vesicle integrity following systemic administration.

Phil Bhardwaj: Thanks, Chad. Please turn to Slide 20 for an overview of our exciting new Cytope technology. Our Cytope technology is an innovative targeting technology invented by Prothena to reach virtually any cell type and enable precise targeting of intracellular disease pathways in the brain and periphery through an endosomal uptake and escape mechanism that preserves membrane and vesicle integrity following systemic administration. This technology potentially allows for targeting of previously undruggable intracellular disease targets. Each Cytope program is uniquely tailored to target a specific intracellular disease pathway. It is comprised of a cell-internalizing technology, a targeting element derived from a macromolecule, such as an antibody, and may include optional elements, such as the addition of receptor-mediated technology, to enable delivery to specific cells or tissues. Our first disclosed program to utilize this technology is our TDP-43 Cytope program for amyotrophic lateral sclerosis, or ALS. Let's discuss further on Slide 21.

[Company Representative] (Prothena): Thanks, Chad. Please turn to Slide 20 for an overview of our exciting new Cytope technology. Our Cytope technology is an innovative targeting technology invented by Prothena to reach virtually any cell type and enable precise targeting of intracellular disease pathways in the brain and periphery through an endosomal uptake and escape mechanism that preserves membrane and vesicle integrity following systemic administration. This technology potentially allows for targeting of previously undruggable intracellular disease targets. Each Cytope program is uniquely tailored to target a specific intracellular disease pathway. It is comprised of a cell-internalizing technology, a targeting element derived from a macromolecule, such as an antibody, and may include optional elements, such as the addition of receptor-mediated technology, to enable delivery to specific cells or tissues. Our first disclosed program to utilize this technology is our TDP-43 Cytope program for amyotrophic lateral sclerosis, or ALS. Let's discuss further on Slide 21.

Speaker #2: This technology potentially allows for targeting of previously undruggable intracellular disease targets. Each cytoprogram is uniquely tailored to target a specific intracellular disease pathway. It is comprised of a cell internalizing technology, a targeting element derived from a macromolecule such as an antibody, and may include optional elements such as the addition of receptor-mediated technology to enable delivery to specific cells or tissues.

Speaker #2: Our first and closest program to utilize this technology is our TDP-43 cytoprogram for amyotrophic lateral sclerosis, or ALS. Let's discuss further on slide 21.

Phil Bhardwaj: ALS is a progressive, fatal neurodegenerative disease characterized by the selective loss of upper and lower motor neurons, and in the majority of cases, by cytoplasmic aggregation and nuclear depletion of the RNA binding protein TDP-43. Current approved therapies used to treat ALS seek to affect disease progression by targeting broad mechanisms such as excitotoxicity and oxidative stress, rather than the core molecular pathologies. These treatments do not stop or reverse motor neuron degeneration, and to date, provide limited clinical benefits. Consequently, there remains a major unmet need for disease-modifying therapies that directly address TDP-43-driven mechanisms. Using our internally discovered Cytope technology, we have developed an anti-phosphorylated TDP-43 Cytope that is designed to address the core molecular pathology associated with approximately 97% of ALS cases. Dysregulation of TDP-43 triggers both toxic gain-of-function and loss-of-function deficits in the context of disease.

[Company Representative] (Prothena): ALS is a progressive, fatal neurodegenerative disease characterized by the selective loss of upper and lower motor neurons, and in the majority of cases, by cytoplasmic aggregation and nuclear depletion of the RNA binding protein TDP-43. Current approved therapies used to treat ALS seek to affect disease progression by targeting broad mechanisms such as excitotoxicity and oxidative stress, rather than the core molecular pathologies. These treatments do not stop or reverse motor neuron degeneration, and to date, provide limited clinical benefits. Consequently, there remains a major unmet need for disease-modifying therapies that directly address TDP-43-driven mechanisms. Using our internally discovered Cytope technology, we have developed an anti-phosphorylated TDP-43 Cytope that is designed to address the core molecular pathology associated with approximately 97% of ALS cases. Dysregulation of TDP-43 triggers both toxic gain-of-function and loss-of-function deficits in the context of disease.

Speaker #2: ALS is a progressive, fatal neurodegenerative disease characterized by the selective loss of upper and lower motor neurons, and, in the majority of cases, by cytoplasmic aggregation and nuclear depletion of the RNA-binding protein TDP-43.

Speaker #2: Current approved therapy is used to treat ALS, seek to affect disease progression by targeting broad mechanisms such as excitotoxicity and oxidative stress rather than the core molecular pathology.

Speaker #2: These treatments do not stop or reverse motor neuron degeneration and, to date, provide limited clinical benefit. Consequently, there remains a major unmet need for disease-modifying therapies that directly address TDP-43-driven mechanisms.

Speaker #2: Using our internally discovered Cytoprogram technology, we have developed an anti-phosphorylated TDP-43 Cytoprogram that is designed to address the core molecular pathology associated with approximately 97% of ALS cases.

Speaker #2: This regulation of TDP-43 triggers both toxic gain-of-function and loss-of-function deficits in the context of disease. A key challenge in the field has been how to effectively target intracellular phosphorylated TDP-43 aggregates, which are broadly deposited in the CNS and periphery, while preserving normal TDP-43 function.

Phil Bhardwaj: A key challenge in the field has been how to effectively target intracellular phosphorylated TDP-43 aggregates, which are broadly deposited in the CNS and periphery while preserving normal TDP-43 function. As shown in the slide, neither conventional antibodies, small molecules, or oligonucleotide have all of the components needed to effectively target and eliminate intracellular phosphorylated TDP-43 aggregates. Enter TDP-43 Cytope on Slide 22. TDP-43 Cytope was designed to specifically bind to and degrade intracellular phosphorylated TDP-43 aggregates that are central to ALS pathologies.... In preclinical studies, our unique TDP-43 Cytope has been demonstrated to degrade phosphorylated TDP-43-associated aggregates located in the cytoplasm, addressing the toxic gain-of-function pathology. In addition, we have demonstrated that administration of our TDP-43 Cytope addresses the related loss-of-function biology, potentially through restoration of TDP-43 trafficking and the function of normal TDP-43 in the nucleus.

[Company Representative] (Prothena): A key challenge in the field has been how to effectively target intracellular phosphorylated TDP-43 aggregates, which are broadly deposited in the CNS and periphery while preserving normal TDP-43 function. As shown in the slide, neither conventional antibodies, small molecules, or oligonucleotide have all of the components needed to effectively target and eliminate intracellular phosphorylated TDP-43 aggregates. Enter TDP-43 Cytope on Slide 22. TDP-43 Cytope was designed to specifically bind to and degrade intracellular phosphorylated TDP-43 aggregates that are central to ALS pathologies.... In preclinical studies, our unique TDP-43 Cytope has been demonstrated to degrade phosphorylated TDP-43-associated aggregates located in the cytoplasm, addressing the toxic gain-of-function pathology. In addition, we have demonstrated that administration of our TDP-43 Cytope addresses the related loss-of-function biology, potentially through restoration of TDP-43 trafficking and the function of normal TDP-43 in the nucleus.

Speaker #2: As shown in the slide, neither conventional antibodies, small molecules, or oligonucleotides have all of the components needed to effectively target and eliminate intracellular phosphorylated TDP-43 aggregates.

Speaker #2: And our TDP-43 cytoprogram on Slide 22. The TDP-43 cytoprogram was designed to specifically bind to and degrade intracellular phosphorylated TDP-43 aggregates that are central to ALS pathology.

Speaker #2: In preclinical studies, our unique TDP-43 cytoprogram has been demonstrated to degrade phosphorylated TDP-43–associated aggregates located in the cytoplasm, addressing the toxic gain-of-function pathology.

Speaker #2: In addition, we have demonstrated that administration of our TDP-43 cytoprogram addresses the related loss of function biology potentially through restoration of TDP-43 trafficking and the function of normal TDP-43 in the nucleus.

Phil Bhardwaj: Importantly, the unmatched targeting specificity suggests that we may effectively reduce the pathogenic phosphorylated TDP-43 aggregates while preserving normal TDP-43 activity throughout the body. Moving to slide 23, which highlights some of the key data presented at the Society for Neuroscience Congress in November of last year. On the left, we show supportive data on how TDP-43 Cytope addresses toxic gain-of-function by significantly reducing brain and muscle pathology in a highly aggressive ALS mouse model following systemic administration. These findings are particularly compelling, given the rapid, persistent, and aggressive accumulation of pathogenic aggregates in the RNLSA transgenic mouse model of ALS. On the right, we show supportive data demonstrating the TDP-43 Cytope also addresses the loss-of-function biology. Here, TDP-43 Cytope attenuated RNA missplicing caused by cytoplasmic TDP-43 aggregation in both human neuronal cells and mice.

[Company Representative] (Prothena): Importantly, the unmatched targeting specificity suggests that we may effectively reduce the pathogenic phosphorylated TDP-43 aggregates while preserving normal TDP-43 activity throughout the body. Moving to slide 23, which highlights some of the key data presented at the Society for Neuroscience Congress in November of last year. On the left, we show supportive data on how TDP-43 Cytope addresses toxic gain-of-function by significantly reducing brain and muscle pathology in a highly aggressive ALS mouse model following systemic administration. These findings are particularly compelling, given the rapid, persistent, and aggressive accumulation of pathogenic aggregates in the RNLSA transgenic mouse model of ALS. On the right, we show supportive data demonstrating the TDP-43 Cytope also addresses the loss-of-function biology. Here, TDP-43 Cytope attenuated RNA missplicing caused by cytoplasmic TDP-43 aggregation in both human neuronal cells and mice.

Speaker #2: Importantly, the unmatched targeting specificity suggests that we may effectively reduce the pathogenic phosphorylated TDP-43 aggregates while preserving normal TDP-43 activity throughout the body. Moving to Slide 23, which highlights some of the key data presented at the Society for Neuroscience Congress in November of last year.

Speaker #2: On the left, we show supportive data on how TDP-43 cytoprogram addresses toxic gain of function by significantly reducing brain and muscle pathology in a highly aggressive ALS mouse model following systemic administration.

Speaker #2: These findings are particularly compelling given the rapid, persistent, and aggressive accumulation of pathogenic aggregates in the RNLSA transgenic mouse model of ALS. On the right, we show supportive data demonstrating the TDP-43 cytoprogram also addresses the loss-of-function biology.

Speaker #2: Here, TDP-43 cytoprogram attenuated RNA missplicing caused by cytoplasmic TDP-43 aggregation in both human neuronal cells and mice. This is exciting data from our TDP-43 cytoprogram program and supports the potential of our cytoprogram technology more broadly.

Phil Bhardwaj: This is exciting data from our TDP-43 Cytope program and supports the potential of our Cytope technology more broadly. We look forward to continuing to elucidate the potential of this program and the technology. Let's move to slide 24 to provide an update on our PRX012 transferrin receptor preclinical program, or PRX012 TfR. Trontinemab is an anti-Aβ antibody developed from gantenerumab to also include transferrin receptor binding technology. So far, reported data indicate the addition of transferrin targeting in trontinemab has resulted in improvements over gantenerumab, including significantly decreased the time required to achieve meaningful amyloid reduction and substantially lower risk of ARIA-E associated with amyloid-targeting antibodies. Given the potential of our PRX012 antibody, which is based in part on our demonstration of the activity of this antibody in the clinical setting, we believe the combination of transferrin receptor binding technology could be very exciting.

[Company Representative] (Prothena): This is exciting data from our TDP-43 Cytope program and supports the potential of our Cytope technology more broadly. We look forward to continuing to elucidate the potential of this program and the technology. Let's move to slide 24 to provide an update on our PRX012 transferrin receptor preclinical program, or PRX012 TfR. Trontinemab is an anti-Aβ antibody developed from gantenerumab to also include transferrin receptor binding technology. So far, reported data indicate the addition of transferrin targeting in trontinemab has resulted in improvements over gantenerumab, including significantly decreased the time required to achieve meaningful amyloid reduction and substantially lower risk of ARIA-E associated with amyloid-targeting antibodies. Given the potential of our PRX012 antibody, which is based in part on our demonstration of the activity of this antibody in the clinical setting, we believe the combination of transferrin receptor binding technology could be very exciting.

Speaker #2: We look forward to continuing to elucidate the potential of this program and the technology. Let's move to Slide 24 to provide an update on our PRX-12 transferrin receptor preclinical program, our PRX-12 TFR.

Speaker #2: PRONTINAMAP is an anti-A beta antibody developed from Gansen-Aramab to also include transferrin receptor binding technology. So far, reported data indicate the addition of transferrin targeting in PRONTINAMAP as resulted in improvements over Gansen-Aramab, including significantly decreased the time required to achieve meaningful amyloid reduction and substantially lower risk of RIE associated with amyloid targeting antibodies.

Speaker #2: Given the potential of our PRX-12 antibody, which is based in part on our demonstration of the activity of this antibody in the clinical setting, we believe the combination of transferrin receptor binding technology could be very exciting.

Speaker #2: Let's move to Slide 25. Last year, we reported interim results from the PRX-12 ASCENT Phase 1 clinical program, including immune reduction in amyloid PET to approximately 27.5 centiloids, ADMON-12, for patients that received a monthly subcutaneous dose of 400 milligrams of PRX-12 from the start of the study.

Phil Bhardwaj: Let's move to slide 25. Last year, we reported interim results from the PRX012 ASCEND phase 1 clinical program, including a mean reduction in amyloid PET to approximately 27.5 centiloids at month 12 for patients that received a monthly subcutaneous dose of 400mg of PRX012 from the start of the study. Preliminary results for patients reaching 18 months of treatment with a 400mg dose showed a mean reduction in amyloid PET to approximately 16 centiloids, and 9 of the 12 patients achieved amyloid negativity, defined as having a centiloid value less than 24.1. But as we reported in August, the ARIA-E rates for PRX012 were non-competitive relative to FDA-approved anti-Aβ antibodies. Based on these collective results, we believe a PRX012 TfR approach is appropriate for further development.

[Company Representative] (Prothena): Let's move to slide 25. Last year, we reported interim results from the PRX012 ASCEND phase 1 clinical program, including a mean reduction in amyloid PET to approximately 27.5 centiloids at month 12 for patients that received a monthly subcutaneous dose of 400mg of PRX012 from the start of the study. Preliminary results for patients reaching 18 months of treatment with a 400mg dose showed a mean reduction in amyloid PET to approximately 16 centiloids, and 9 of the 12 patients achieved amyloid negativity, defined as having a centiloid value less than 24.1. But as we reported in August, the ARIA-E rates for PRX012 were non-competitive relative to FDA-approved anti-Aβ antibodies. Based on these collective results, we believe a PRX012 TfR approach is appropriate for further development.

Speaker #2: Preliminary results for patients reaching 18 months of treatment with the 400-milligram dose showed immune reduction in amyloid PET to approximately 16 centiloids. In nine of the 12 patients who achieved amyloid negativity, the findings had a centiloid value less than 24.1.

Speaker #2: But as we reported in August, the RIE rates for PRX-12 were non-competitive relative to FDA-approved anti-A beta antibodies. Based on these collective results, we believe a PRX-12 TFR approach is appropriate for further development.

Speaker #2: It is our desire to improve over PRX-12 while maintaining a convenient once-monthly subcutaneous administration. Currently, we are exploring partnership interests for PRX-12 TFR while advancing the program preclinically.

Phil Bhardwaj: It is our desire to improve over PRX012 while maintaining a convenient once-monthly subcutaneous administration. Currently, we are exploring partnership interest for PRX012 TfR while advancing the program preclinically. With that, I'll turn it over to Tran to review our financial results.

[Company Representative] (Prothena): It is our desire to improve over PRX012 while maintaining a convenient once-monthly subcutaneous administration. Currently, we are exploring partnership interest for PRX012 TfR while advancing the program preclinically. With that, I'll turn it over to Tran to review our financial results.

Speaker #2: With that, I'll turn it over to Tron to review our financial results.

Speaker #3: Thanks, Phil. Please turn to slide 27. Today, we reported financials favorable to our 2025 financial guidance. Please refer to our press release for a detailed breakdown of our financial results.

Tran Nguyen: Thanks, Bill. Please turn to slide 27. Today, we reported financial results that were in line or favorable to our 2025 financial guidance. Please refer to our press release for a detailed breakdown of our financial results. In terms of our 2025 financial performance relative to guidance, we had net cash used in operating and investing activities of $163.7 million, which was favorable to our guidance range of $170 to 178 million. Net loss was $244.1 million, which was in line with our guidance range of $240 to 248 million.

Speaker #3: In terms of our 2025 financial performance relative to guidance, we had net cash used in operating and investing activities of $163.7 million which was favorable to our guidance range of $170 to $178 million.

Speaker #3: Net loss was $244.1 million which was in line with our guidance range of $240 to $248 million. As of December 31st, 2025, PRONTINA had $308.4 million in cash, cash equivalents, and restricted cash.

Tran Nguyen: As of 31 December 2025, Prothena had $308.4 million in cash, cash equivalents, and restricted cash, which was favorable to our guidance of $298 million. As of 12 February 2026, Prothena had 53.8 million ordinary shares outstanding. Additionally, we continue to have a simple capital structure with zero debt. Turning to our 2026 financial guidance on slide 28, we expect our full year 2026 net cash used in operating and investing activities to be between $50 and $55 million. We expect to end the year with approximately $255 million in cash, cash equivalents, and restricted cash, which represents the midpoint of the range.

Speaker #3: Which was favorable to our guidance of $298 million. As of February 12, 2026, Prothena had 53.8 million ordinary shares outstanding. Additionally, we continue to have a simple capital structure with zero debt.

Speaker #3: Turning to our 2026 financial guidance on Slide 28, we expect our full-year 2026 net cash used in operating and investing activities to be between $50 million and $55 million.

Speaker #3: We expect to end the year with approximately $255 million in cash, cash equivalents, and restricted cash. Which represents the midpoint of the range. The estimated full year 2026 net cash used in operating and investing activities is primarily driven by an estimated net loss of $67 to $72 million.

Tran Nguyen: The estimated full year 2026 net cash used in operating and investing activities is primarily driven by an estimated net loss of $67 to 72 million, which includes an estimated 24 million of non-cash share-based compensation expense. And as a reminder, our 2026 financial guidance does not include the up to $105 million of potential aggregate clinical milestone payments from strategic partners in 2026, related to the advancement of both coramitug for ATTR amyloidosis with cardiomyopathy by Novo Nordisk... and PRX019 for neurodegenerative diseases by Bristol Myers Squibb. With that, I'll turn the call back to Gene for closing remarks.

Speaker #3: Which includes an estimated $24 million of non-cash share-based compensation expense. And as a reminder, our 2026 financial guidance does not include the up to $105 million of potential aggregate clinical milestone payments from strategic partners in 2026 related to the advancement of both Parametug for ATTR amyloidosis with cardiomyopathy by Novo Nordisk and PRX-19 for neurodegenerative diseases by Bristol Myers Squibb.

Speaker #3: With that, I'll turn the call back to Jean for closing remarks.

Speaker #1: Thank you, Tron. Moving to Slide 30. As we've shared today, we have a robust pipeline of programs that address significant unmet needs for potentially millions of patients' caregivers and their families.

Gene Kinney: Thank you, Tran. Moving to slide 30. As we've shared today, we have a robust pipeline of programs that address significant unmet needs for potentially millions of patients, caregivers, and their families. It is our mission to continue to further develop our programs and elucidate the potential of our technology to address these needs. Let me end by recapping our 2026 strategic priorities, which are to capture the value embedded in our clinical partnerships, including up to $105 million in clinical milestones in 2026. To implement a share redemption program and invest in our preclinical portfolio to support our ongoing partnering efforts in the form of research collaborations, especially on our suite of technology, and drive future partnerships for our unpartnered programs.

Speaker #1: It is our mission to continue to further develop our programs and elucidate the potential of our technology to address these needs. Let me end by recapping our 2026 strategic priorities.

Speaker #1: These are to capture the value embedded in our clinical partnerships, including up to $105 million in clinical milestones in 2026; to implement a share redemption program; and to invest in our preclinical portfolio to support our ongoing partnering efforts in the form of research collaboration, especially on our cytope technology.

Speaker #1: And drive future partnerships for our unpartnered programs. I'm proud of Prothena's execution and resilience in 2025, setting us up for an exciting future. We are well capitalized with a robust cash position and remain focused on delivering long-term shareholder value by delivering on our mission to patients.

Gene Kinney: I'm proud of Prothena's execution and resilience in 2025, setting us up for an exciting future. We're well capitalized with a robust cash position and remain focused on delivering long-term shareholder value by delivering on our mission to patients. With that, we will now open the call to Q&A. Operator?

Speaker #1: With that, we will now open the call to Q&A. Operator?

Operator: Ladies and gentlemen, if you wish to ask a question, please press star followed by one on your touch-tone telephone. If your question has been answered, press star one again. Please limit yourself to one question. I repeat, please limit yourself to one question. Please stand by for your first question. Your first question comes from the line of Yasmin Rahimi with Piper Sandler. Please go ahead.

Speaker #4: Ladies and gentlemen, if you wish to ask a question, please press star, followed by one, on your touch-tone telephone. If your question has been answered, press star one again.

Speaker #4: Please limit yourself to one question. I repeat, please limit yourself to one question. Please stand by for your first question. Your first question comes from the line of Yasmeen Rahimi with Piper Sandler.

Speaker #4: Please go ahead.

[Analyst] (Piper Sandler): Hi, this is Shannon on for Yasmin Rahimi. Congrats on the great progress, guys, and thank you so much for taking our question. We just wanted to know, with the primary completion dates for the partnered program trials for ISO and Cleopatra not expected until 2029, can you maybe walk us through some of the key milestones to look out for in 2026 and 2027, and what those milestones might be contingent on?

[Company Representative] (Piper Sandler): Hi, this is Shannon on for Yasmin Rahimi. Congrats on the great progress, guys, and thank you so much for taking our question. We just wanted to know, with the primary completion dates for the partnered program trials for ISO and Cleopatra not expected until 2029, can you maybe walk us through some of the key milestones to look out for in 2026 and 2027, and what those milestones might be contingent on?

Speaker #5: Hi, this is Shannon on for Yas Rahimi. Congrats on the great progress, guys, and thank you so much for taking our question. We just wanted to know, with the primary completion dates for the partnered program trials for ESO and Cleopatra not expected until 2029,

Speaker #5: Could you maybe walk us through some of the key milestones to look out for in 2026, in 2027, and what those milestones might be contingent on?

Speaker #1: Yeah, thanks for the question, Shannon. So, as we kind of laid out, we have a lot of things happening this year into next year.

Gene Kinney: Yeah, thanks for the question, Shannon. As we kind of laid out, we have a lot of things happening this year into next year, and for the next several years. I think as we look to some of our emerging technologies, some of the Cytope activities that we talked about on the call, we certainly expect to share more of that information this year through scientific presentations, in particular around our TDP-43 Cytope program, and obviously, the progress we're making there. We talked about in 2027, in the first half of 2027, starting to see the data coming from our partner tau program with Bristol Myers Squibb.

Speaker #1: And for the next several years. So I think as we look to some of our emerging technologies, some of the cytope activities that we talked about on the call, we certainly expect to share more of that information this year through scientific presentations.

Speaker #1: In particular, around our TDP-43 cytope program and obviously the progress we're making there. We talked about, in 2027, in the first half of 2027, starting to see the data coming from our partner TAO program with Bristol Myers Squibb.

Gene Kinney: So we think that phase 2 program would be very interesting, as it was outlined by Chad on the call. Clearly, the primary outcome measure there is tau PET. So, you know, we think this is gonna be a very interesting evaluation of our MTBR targeting tau approach. And then obviously, very much looking forward to the two phase 3 readouts with primary expected completion dates in 2029, as you outlined, for both, coramitug and prasinezumab.

Speaker #1: So we think that phase two program would be very interesting as it was outlined by Chad on the call. Clearly, the primary outcome measure there is TAO PET.

Speaker #1: So we think this is going to be a very interesting evaluation of our MTBR targeting TAO approach. And then obviously very much looking forward to the two phase three readouts with primary expected completion dates in 2029 as you outlined.

Speaker #1: For both Parametug and Pratinizumab and clearly as we indicated, not only do we think that those are well positioned based on the phase two results, to be tested in an adequate way in the phase three studies.

Gene Kinney: And clearly, as we indicated, not only do we think that those are well-positioned based on the phase two results to be, you know, tested in an adequate way in the phase three studies, but also represents the potential for significant medical advance in areas with pretty high unmet need, and also I think very interesting economic opportunities with respect to the commercial opportunity there. But so yeah. So I think it's actually gonna be a very busy time for us. And the only other thing I would mention here, and maybe Tran, if you want to speak to it further, is we look forward to instituting our share redemption program this year as well.

Speaker #1: But also represent the potential for significant medical advance in areas with pretty high unmet need and also I think very interesting economic opportunities with respect to the commercial opportunity there.

Speaker #1: But so yeah, so I think it's actually going to be a very busy time for us. And the only other thing I would mention here, and maybe Tron, if you want to speak to it further, as we look forward to instituting our share redemption program this year as well.

Gene Kinney: So that's something that we needed to get approval for in an EGM, which took place at the end of last year. We needed Irish High Court approval for that. And, you know, I think this year we expect to implement that.

Speaker #1: So that's something that we needed to get approval for in an EGM, which took place at the end of last year. We needed Irish High Court approval for that.

Speaker #1: And I think this year we expect to implement that.

Speaker #3: Yeah, we'll make further announcements with that closer to the filing of our 10-K. But that also being said, to repeat that this year we'll also have potentially up to $105 million worth of clinical milestones.

Tran Nguyen: Yeah, and we'll make further announcements with that closer to the filing of our 10-K. But that also being said, to repeat that this year we'll also have, you know, potentially up to $105 million worth of clinical milestones from our partners, which Gene covered in our prepared remarks, from coramitug and PRX019. So exciting 2026 in view.

Speaker #3: From our partners, which Jean covered in our prepared remarks. From Parametug and X19. So an exciting 2026 and beyond.

Speaker #5: Great, thank you so much.

[Analyst] (Piper Sandler): Great. Thank you so much.

[Company Representative] (Piper Sandler): Great. Thank you so much.

Speaker #4: Your next question comes from the line of Michael DeFiore with Evercore ISI. Please go ahead.

Operator: Your next question comes from the line of Michael DiFiore with Evercore ISI. Please go ahead.

Speaker #6: Hey guys, thanks so much for taking my question. One on PRX-012. If you could just elaborate how you try to keep the amyloid data story alive.

Michael DiFiore: Hey, guys. Thanks so much for taking my question. One on PRX012, if you could just elaborate how you will try to keep the amyloid beta story alive versus much larger, more advanced competitors. And as a relative follow-up, there are many transferrin receptor tech platforms out there. Maybe you could describe what the ideal transferrin platform would offer that would make you want to partner. Thank you.

Speaker #6: Versus much larger, more advanced competitors. And as a relative follow-up, there are many transferrin receptor tech platforms out there. Maybe you could describe what the ideal transferrin platform would offer that would make you want to partner.

Speaker #6: Thank you.

Speaker #1: Yeah, so thank you for the question. You broke up a little bit, but I think I got most of it. And maybe I can I'll ask Brandon to jump in just with respect to the BD space a little bit here.

Gene Kinney: Yeah. So thank you for the question. You broke up a little bit, but I think I got most of it, and maybe I can... I'll ask Brandon to jump in just with respect to the BD space a little bit here. But just to answer the question, first in terms of why we're excited about our PRX012 transferrin-based approach, you know, look, there are two elements to these types of molecules, right? And I think, you know, a lot of what we've learned about this space and the potential of adding transferrin technology or receptor technology to anti-beta antibodies comes from the gantenerumab/trontinemab approach....

Speaker #1: But just to answer the question, first, in terms of why we're excited about our PRX-12 transparent-based approach, look, there are two elements to these types of molecules, right?

Speaker #1: And I think a lot of what we've learned about this space and the potential of adding transparent technology or receptor technology to anti-beta antibodies comes from the Gansen-Nurmab/Tron-Tinimab approach.

Gene Kinney: You know, and there, I think we had a good understanding of what the activity rate on both the, you know, the amyloid removal side as well as the ARIA-E side for gantenerumab was, and then adding a transferrin-based approach, that, you know, it had certain characteristics to it. The Roche approach, I think, you know, gave us the results in trontinemab that we can directly compare to gantenerumab. You know, what we think we have here with PRX012 is we've described now data for the parent molecule, PRX012, and with a once-monthly subcutaneous presentation, you know, showing what we think are very interesting and impressive results in terms of amyloid removal.

Speaker #1: And there, I think we had a good understanding of what the activity rate on both the amyloid removal side as well as the ARIA E side for Gansen-Nurmab was.

Speaker #1: And then adding a transparent-based approach that had certain characteristics to it. This is the Roche approach. I think gave us the results in Tron-Tinimab that we can directly compare to Gansen-Nurmab.

Speaker #1: What we think we have here with PRX-12 is we've described now data for the parent molecule PRX-12. And with a once-monthly subcutaneous presentation, showing what we think are very interesting and impressive results in terms of amyloid removal.

Speaker #1: So at a flat dose with once-a-month subcutaneous administration, seeing the majority of patients be amyloid negative, and seeing the average senoloid value being quite low.

Gene Kinney: So, you know, at a flat dose, once a month subcutaneous administration, seeing the majority of patients be amyloid negative, seeing the average amyloid value being quite low, you know, we think positions us in a way that we can say this is a very convenient and very robust antibody with respect to amyloid removal. You know, what we thought was a little less competitive in those results were some of the ARIA-E rates.

Speaker #1: We think positions us in a way that we can say this is a very convenient and very robust antibody with respect to amyloid removal.

Speaker #1: What we thought was a little less competitive in those results were some of the ARIA E rates. And so here, with this technology provided that we follow the path with respect to transparent that others have seen success with, I'll Gansen-Nurmab and Tron-Tinimab, that we have the opportunity to take advantage of that emerging biology and potentially see an improvement in the overall profile of PRX-12 with the PRX-12 transparent program.

Gene Kinney: And so here, with this technology, provided that, you know, we follow the path with respect to transferrin, that you know that others have seen success with, à la gantenerumab and trontinemab, that we have the opportunity to take advantage of that emerging biology and, you know, potentially see an improvement in the overall profile of PRX012 with the PRX012 transferrin program. So we're excited about that. We think that's something that we can move forward relatively quickly, and get a pretty definitive answer, you know, very early in phase 1 clinical testing, given that we know the characteristics of the parent PRX012 so well. As you say, there's been a lot of interest in this space, with respect to licensing, and we think that's a good thing.

Speaker #1: So we're excited about that. We think that's something that we can move forward with relatively quickly and get a pretty definitive answer very early in Phase 1 clinical testing, given that we know the characteristics of the parent PRX-12 so well.

Speaker #1: As you say, there's been a lot of interest in this space with respect to licensing and we think that's a good thing. We're certainly happy to see that the momentum is not only continuing, but I think continuing to build around these types of approaches, which have the potential to decrease some of the AE profile limitations of the anti-beta antibodies.

Gene Kinney: You know, we're certainly happy to see that the momentum is not only continuing, but I think continuing to build around these types of approaches, which have the potential to decrease some of the AE profile limitations of the anti-beta antibodies, and potentially increase the primary mechanism of action, which is removal of amyloid. But maybe, Brandon, you can speak a little bit more to just some of the dynamics of what's happening in the business development space, particularly in this class.

Speaker #1: And potentially increase the primary mechanism of action, which is removal of amyloid. But maybe Brandon, you can speak a little bit more to just some of the dynamics of what's happening in the business development space, particularly in this class.

Speaker #3: Yeah, appreciate that, Jean. And appreciate the question. So from the market's perspective, there is clearly a high level of interest for the approach that we're taking.

Brandon Smith: Yeah, I appreciate that, Gene, and appreciate the question. So, from the market's perspective, there is clearly a high level of interest for the approach that we're taking. And what we're building off of relative to what gantenerumab saw when they added transferrin and turned it into trontinemab, we think we're uniquely suited to build upon that story. And the market has begun to recognize that, and our dialogues are active. Probably the best I could say about the BD dialogue. What's really interesting about the space, though, is also the opportunity potentially to grow.

Speaker #3: And what we're building off of relative to what Gansen-Nurmab saw when they added transparent and turned it into Tron-Tinimab, we think we're uniquely suited to build upon that story.

Speaker #3: And the market has begun to recognize that in our dialogue, our active probably the best I can say about the BD dialogues. What's really interesting about the space, though, is also the opportunity potentially to grow.

Brandon Smith: And what we're following very closely is that profile that Gene described, which is once a month subQ, leveraging a better ARIA profile that we expect to see and hope to see coming with the addition of transferrin, is uniquely suited for where the market is headed, not just early Alzheimer's disease, which we think we have a unique capability there, but really around the presymptomatic space. We're looking forward to what the field is seeing in the presymptomatic space. We expect readouts this year. And that opens up a unique opportunity for us because we are a paradigm that is much less frequent, much less cumbersome. And when you're talking about those presymptomatic patients, that's exactly what they need. They need something that is uniquely set up for them, something that is not cumbersome, and it potentially helps prevent the progressions.

Speaker #3: And what we're following very closely is that profile that Jean described, which is once a month sub-Q, leveraging a better ARIA profile that we expect to see and hope to see coming with the addition of transparent.

Speaker #3: Is uniquely suited for where the market is headed, not just early to Alzheimer's disease, which we think we have a unique capability there, but really around the presymptomatic space.

Speaker #3: We're looking forward to what the field is seeing in the presymptomatic space. We expect readouts this year, and that opens up a unique opportunity for us because we are a paradigm that is much less frequent, much less cumbersome.

Speaker #3: And when you're talking about those presymptomatic patients, that's exactly what they need. They need something that is uniquely set up for them, something that is not cumbersome and potentially helps prevent the progression of these.

Speaker #3: So that's recognized in the field and something that is very interesting. Obviously, we're also very interested in the data that we're generating internally to help build upon that program we hope to talk about that over the course of this year.

Brandon Smith: So that's recognized in the field and something that is very interesting. Obviously, we're also very interested in the data that we're generating internally to help build upon that program. We hope to talk about that over the course of this year, in terms with you and with our potential partners.

Speaker #3: And certainly with you and with our potential partners.

Gene Kinney: Thank you.

Speaker #4: Your next question comes from the line of Eric Schmidt with Cantor Fitzgerald. Please go ahead.

Operator: Your next question comes from the line of Eric Schmidt with Cantor Fitzgerald. Please go ahead.

Speaker #5: Hi guys, this is Alexa Diemer on for Eric. Congrats on the great year. So for the phase one study of 019, which is expected to complete this year, do you plan to share data from the study this year?

Alexa Deemer: Hi, guys. This is Alexa Diemer on for Eric. Congrats on the great year. So for the phase 1 study of PRX019, which is expected to complete this year, do you plan to share data from the study this year, and what do you want to see for this program to advance? Thank you.

Speaker #5: And what do you want to see for this program to advance? Thank you.

Speaker #1: Yeah, it's a great question. Thank you for the question. So with PRX-19, that is a program that we have a partnership with Bristol-Myers Squibb on.

Gene Kinney: Yeah, it's a great question. Thank you for the question. So with PRX019, that is a program that we have a partnership with Bristol Myers Squibb on. We have not, for strategic reasons, talked about the target of that yet, except to say that it's broadly applicable to neurodegeneration. I think as Chad mentioned in his comments, that phase 1 study is being conducted by us. We expect that to complete this year. And what we would then do is share that information with our partners at Bristol Myers Squibb.

Speaker #1: We have not, for strategic reasons, talked about the target of that yet, except to say that it's broadly applicable to neurodegeneration. I think as Chad mentioned in his comments, that phase one study is being conducted by us.

Speaker #1: We expect that to complete this year. And what we would then do is share that information with our partners at Bristol-Myers Squibb. And I think you heard both Tron earlier say, and I had said in my remarks as well, that the potential to achieve up to 105 million dollars this year through partnership programs, some of that is tied to decisions made around PRX-19.

Gene Kinney: And I think you heard, you know, both Tran earlier say, and I had said in my remarks as well, that the potential to achieve up to $105 million this year through partnership programs, some of that is tied to decisions made around PRX019. So what we expect is that we'll share that information with Bristol Myers Squibb. At the end of the day, it will be up to them to decide what and how much of that information to share publicly. But obviously, we'll be talking about that a little bit later this year. And with that said, maybe, Tran, you can add some-

Speaker #1: So what we expect is that we'll share that information with Bristol-Myers Squibb at the end of the day. It will be up to them to decide what and how much of that information to share publicly.

Speaker #1: But obviously, we'll be talking about we'll be talking about that a little bit later this year and with that said, maybe Tron, you can add some additional comments.

Brandon Smith: Yes. Just, just a reminder, they have global rights to this program, and they exercised it. They paid us $80 million for it. Just hence the data is theirs, and it's theirs to decide on how to disseminate that. That being said, what we would do is, of course, announce if we've earned and they've, they've taken that molecule forward into further clinical development, and that's when we'll earn the clinical milestone associated with X nineteen. Got it. Thanks so much.

Tran Nguyen: Yes. Just, just a reminder, they have global rights to this program, and they exercised it. They paid us $80 million for it. Just hence the data is theirs, and it's theirs to decide on how to disseminate that. That being said, what we would do is, of course, announce if we've earned and they've, they've taken that molecule forward into further clinical development, and that's when we'll earn the clinical milestone associated with X nineteen. Got it. Thanks so much.

Speaker #3: Just a reminder, they have global rights to this program. They exercised it. They paid us $80 million for it. So, hence, the data is theirs and it's theirs to decide on how to disseminate that.

Speaker #3: So that being said, what we would do is, of course, announce if we've earned and they've taken that molecule forward into further clinical development.

Speaker #3: And that's when we'll earn the clinical milestone associated with X19.

Speaker #5: Got it. Thanks so much.

Speaker #4: Your next question comes from the line of Jason Butler with Citizens. Please go ahead.

Operator: Your next question comes from the line of Jason Butler with Citizens. Please go ahead.

Jason Butler: Hi, thanks for taking the question. Can you maybe just from a broader level, speak to how you would think about the amount of data necessary to secure a partnership for the Cytope platform? Or ultimately, if you made the decision to advance a program into the clinic yourselves from the Cytope platform, what data you'd want to see to de-risk the initial clinical development? Thank you.

Speaker #6: Hi, thanks for taking the question. Can you maybe just from a broader level, speak to how you would think about the amount of data necessary to secure a partnership for the SITO platform or ultimately if you made the decision to advance a program into the clinic yourselves from the SITO platform, what data you'd want to see to de-risk the initial clinical development?

Speaker #6: Thank you.

Speaker #1: Yeah, thanks for the question, Jason. So maybe I can start with a little bit of the biology here. And then Brandon can speak a little bit to just business development strategy.

Gene Kinney: Yeah. Thanks, thanks for the question, Jason. So, maybe I can start with a little bit of the biology here, and then Brandon can speak a little bit to just the development strategy. But, I think from a TDP-43 perspective, the data we shared last year, I think was interesting, both with respect to the Cytope technology and also to the idea of targeting TDP-43 in the context of ALS.

Speaker #1: But I think from a TDP-43 perspective, the data we shared last year, I think was interesting both with respect to the SITO technology and also to the idea of targeting TDP-43 in the context of ALS.

Speaker #1: And Phil covered this in some of his remarks, but I think for the SITO technology, one of the things you clearly saw in particularly in those animal studies, the in vivo animal studies, in the RNLS-8 mice, is you saw that with systemic administration, you were not only seeing active engagement with this intracellular target in a very disease or pathological specific way, but you were seeing actually removal of that target and in the CNS, you were seeing that as well.

Gene Kinney: Phil covered this in some of his remarks, but I think for the Cytope technology, you know, one of the things you clearly saw, in particularly in those animal studies, the in vivo animal studies, in the RNLs eight mice, is you saw that with systemic administration, you know, you were not only seeing active engagement with this intracellular target in a very disease or pathological specific way, but you were seeing actually removal of that target, and in the CNS, you were seeing that as well. So that's an important context here, which is systemic administration, you're seeing robust CNS activity. So not only is, does this platform appear to allow us to target things in the intracellular space, but also seems to allow us to do so in the central nervous system as well.

Speaker #1: So that's an important context here, which is systemic administration, you're seeing robust CNS activity. So not only is it does this platform appear to allow us to target things in the intracellular space, but also seems to allow us to do so in the central nervous system as well.

Speaker #1: And so, we think that that's a really important lesson learned from the technology. And again, as was mentioned by Phil, we're not seeing any evidence that we're disrupting endosomes or causing problems that other forms of technology that have attempted to do these sorts of things have suffered from.

Gene Kinney: So we think that that's a really important lesson learned from the technology. Again, as was mentioned by Phil, we're not seeing any evidence that we're disrupting endosomes or causing problems that other forms of technology that have attempted to do these sorts of things have suffered from. I think in terms of ALS, it's particularly interesting. We know 97%, again, Phil covered some of this, 97% of patients have TDP-43 dysfunction as a core element of their pathology. And one of the challenges in targeting TDP-43 intracellularly directly is how to target the abnormal form of these proteins while leaving the normal form to do its day job, which is essential for cells to function properly.

Speaker #1: I think in terms of ALS, it's particularly interesting. We know 97%, again, Phil covered some of this, 97% of patients have TDP-43 dysfunction as a core element of their pathology.

Speaker #1: And one of the challenges in targeting TDP-43 intracellularly directly is how to target the abnormal form of these proteins while leaving the normal form to do its day job, which is essential for cells to function properly.

Gene Kinney: And so by having a very specific targeting approach, you were able to see that specificity translate into not only kind of sorting out the toxic gain of function, which is the aggregate that you see in the cytosol, but also interestingly, in an in vitro setting in human cell types, correcting the loss of function, which is really the missplicing variants or the missplicing dysfunction that you see in the level of the nucleus. And so that seemed to be corrected as well. So that's very exciting. Targeting an abnormal form of TDP-43, which we know leads to both a loss of function and gain of function, and seeing indications that you can address both. So we're excited by those data.

Speaker #1: And so by having a very specific targeting approach, you were able to see that specificity translate into not only kind of sorting out the toxic gain of function, which is the aggregate that you see in the cytosol, but also interestingly in in vitro setting in human cell types, correcting the loss of function, which is really the missplicing variant or the missplicing dysfunction that you see in the level of the nucleus.

Speaker #1: And so that seemed to be corrected as well. So that's very exciting. Targeting an abnormal form of TDP-43, which we know leads to both a loss of function and gain of function and seeing indications that you can address both.

Speaker #1: So we're excited by those data. We think the mouse model, which is an extraordinarily aggressive mouse model, most folks in an unchanged way, if they don't change the mouse model in some way, really struggle to see any effect here.

Gene Kinney: You know, we think the mouse model, which is an extraordinarily aggressive mouse model, most folks in an unchanged way, you know, if they don't change the mouse model in some way, really struggle to see any effect here. We saw some very robust clearing of the intracellular aggregates of TDP-43. So that said, in terms of what we need to see, we think we're very excited by what these data are telling us to date. And obviously, we are interested in continuing to move that program forward. In terms of just the strategy around this program and potentially other programs within our Cytope technology platform, maybe, Brandon, you can speak a little bit to that.

Speaker #1: We saw some very robust clearing of the intracellular aggregates of TDP-43. So that said, in terms of what we need to see, we think we're very excited by what these data are telling us to date.

Speaker #1: And obviously, we are interested in continuing to move that program forward. In terms of just the strategy around this program and potentially other programs within our SITO technology platform, maybe Brandon, you can speak a little bit to that.

Speaker #3: Yeah, I'll maybe the easiest thing to do is just to note that the technology itself didn't become publicly known until November of last year.

Brandon Smith: Yeah, I'll maybe the easiest thing to do is just to note that the technology itself didn't become publicly known until November of last year, right? And so we are, you know, with that, that was the impetus for many subsequent conversations. And what we've been finding is that there really is a very broad set of applications for this technology. And what's unique is that set of applications goes well beyond neuroscience, which is our area of expertise, and it's essentially therapeutic area diagnostics. So we can cast a very wide net from a BD standpoint and solve problems that some of our potential partners are looking to solve by utilizing this technology.

Speaker #3: Right? And so we are with that, that was the impetus for many subsequent conversations. And what we've been finding is that there really is a very broad set of applications for this technology.

Speaker #3: And what's unique is that set of applications goes well beyond neuroscience, which is our area of expertise. And it's essentially therapeutic area agnostic. So we can cast a very wide net from obesity standpoint and solve problems that some of our potential partners are looking to solve by utilizing this technology.

Brandon Smith: One of those specifics is that, and I think we alluded to this in our call, is that, you know, we're already, you know, even in the 3-4 month timeframe that we're talking about, we've established a specific research collaboration, but have others in process that are very focused on learning what we've learned from our TDP-43 program and applying it to a specific target and area of their interest, and applying it in many ways. So that application, much more broadly, is uniquely suited for this technology, and we're excited about the progress we've made. And in parallel, what happens when you have those discussions is those potential partners are actually spending their time and resources to get this in their own hands. So this is new, right?

Speaker #3: One of those specifics is that, and I think we alluded to this in our call, is that we're already even in the three, four months timeframe that we're talking about, we've established specific research collaboration, but have others in process that are very focused on learning what we've learned from our TDP-43 program and applying it to a specific target in an area of their interest.

Speaker #3: And applying it in many ways. So that application much more broadly is uniquely suited for this technology and we're excited about the progress we've made.

Speaker #3: And in parallel with what happens when you have those discussions is those potential partners are actually spending their time and resources to get this in their own hands.

Speaker #3: So this is new, right? This is new and very exciting to them, and they want to make sure that what we see is what they'll also see when they apply to their targets of interest.

Brandon Smith: This is new and very exciting to them, and they want to make sure that what we see is what they'll also see when they apply to their targets of interest. Doing that allows us to then see for the next step, which is a partnership around a target, around a set of targets, or maybe even more broad than that. We're very excited about where we are and a lot more to go.

Speaker #3: And doing that allows us to then see for the next step, which is a partnership around a target, around a set of targets, or maybe even more broad than that.

Speaker #3: So we're very excited about where we are, and there's a lot more to come.

Speaker #2: Your next question comes from the line of Brian Abrams with RBC Capital Markets. Please go ahead.

Operator: Your next question comes from the line of Brian Abrams with RBC Capital Markets. Please go ahead.

Speaker #4: Hi, everyone. This is Nevinon for Brian. Thank you so much for taking our questions. Just a couple from us. So I guess I'm curious to know based on some of the preclinical experiments that you've done in-house, what you think might be maybe some of the mechanistic hypothesis for why the transferrin modification ends up reducing the ARIA risk.

[Analyst] (RBC Capital Markets): Hi, everyone. This is Nevanon for Brian. Thank you so much for taking our questions. Just a couple from us. So I guess I'm curious to know, based on some of the preclinical experiments that you've done in-house, what you think might be maybe some of the mechanistic hypothesis for why the transferrin modification ends up reducing the ARIA risk? And I guess on, along with that, do you expect potential lower heme toxicities with this? And then, an additional clarification question on my end, just wanted to see if the transferrin modification to OH112 would still enable OH112 to be subcutaneously delivered or if this would be IV administered? Thanks so much.

[Company Representative] (RBC Capital Markets): Hi, everyone. This is Nevanon for Brian. Thank you so much for taking our questions. Just a couple from us. So I guess I'm curious to know, based on some of the preclinical experiments that you've done in-house, what you think might be maybe some of the mechanistic hypothesis for why the transferrin modification ends up reducing the ARIA risk? And I guess on, along with that, do you expect potential lower heme toxicities with this? And then, an additional clarification question on my end, just wanted to see if the transferrin modification to OH112 would still enable OH112 to be subcutaneously delivered or if this would be IV administered? Thanks so much.

Speaker #4: And I guess, along with that, do you expect potentially lower heme toxicities with this? And then, an additional clarification question on my end: I just wanted to see if the transferrin modification to 0112 would still enable 0112 to be subcutaneously delivered, or if this would be IV administered.

Speaker #4: Thanks so much.

Speaker #1: Yeah, so, good questions around X12. So let me start, and then maybe Phil, if you have anything to add, you can do so. I think, first, in terms of transferrin and how that actually sorts out some of the ARIA events, there are a lot of hypotheses out there.

Gene Kinney: Yeah. So good questions around PRX012. So let me start and then maybe Phil, if you have anything to add, you can do so. I think first, in terms of transferrin and how that actually sorts out some of the ARIA events, you know, there are a lot of hypotheses out there. I think the one that both Roche and Eli Lilly have put forward as a more likely mechanism is really the location of transferrin and, you know, where that is in the vasculature, in the cerebral vasculature. So this idea that potentially starting to get more penetration into the brain through capillary structures relative to arterial structures may be providing some benefit.

Speaker #1: I think the one that both Roche and Eli Lilly have put forward as a more likely mechanism is really the location of transferrin. And where that is in the vascular, in the cerebral vasculature.

Speaker #1: So, this idea that potentially starting to get more penetration into the brain through capillary structures relative to arterial structures may be providing some benefit. And it has some face validity, inasmuch as we know that when amyloid deposits in the cerebral vasculature, it tends to do so in the larger arterial structures, particularly in the perivascular space.

Gene Kinney: It has some face validity in as much as we know that when amyloid deposits in the cerebral vasculature, it tends to do so in the larger arterial structures, particularly in the perivascular space. And so obviously, you know, moving the route of entry into the capillary system could have some advantages in that respect. So that's one possibility. Another possibility that I think, you know, folks talk about in the field from time to time is an idea of the amount of time that the antibody may sit on amyloid in the vasculature. And potentially with the transferrin-based approach, you get a transcytosis across the blood-brain barrier, which minimizes that dwell time, if you will. And of course, it could be a combination of things as well.

Speaker #1: And so obviously, moving the route of entry into the capillary system could have some advantages in that respect. And so that's one possibility. Another possibility that I think folks talk about in the field from time to time is an idea of the amount of time that the antibody may sit on amyloid in the vasculature and potentially with the transferrin-based approach you get a transcytosis across the blood-brain barrier, which minimizes that dwell time, if you will.

Speaker #1: And of course, it could be a combination of things as well. But I think what it points to—and it's a good question—is that we need to make sure that the transferrin-based approach, and obviously we're taking steps to do this with X12, is something that has similar characteristics to those things that we know already work.

Gene Kinney: But I think what it points to, and it's a good question, is that, you know, we need to make sure that the transferrin-based approach, and obviously we're taking steps to do this with PRX012, is something that has similar characteristics to those things that we know already work. So and again, I think that is a pretty small sample set to date. You know, that's the gantenerumab, trontinemab, story that we've been talking about a little bit. So clearly, we're trying to stay as close to that, down the fairway approach so that we can be sure that whatever that mechanism is, that we're taking advantage of that as well. I think in terms of, you had some other parts of that question there.

Speaker #1: So and again, I think that is a pretty small sample set to date. That's the Gantt and Neuromad trontinimab. Story that we've been talking about a little bit.

Speaker #1: So clearly, we're trying to stay as close to that down the fairway approach so that we can be sure that whatever that mechanism is that we're taking advantage of that as well.

Speaker #1: I think in terms of you had some other parts of that question in there. Oh, yeah. So some of the subQ part of that question, we have no reason to believe that the addition of transferrin at this point would cause us to change our route of entry.

Gene Kinney: Oh, yeah, so, you know, some of the, the subQ part of that question, we have no reason to believe that the addition of transferrin at this point would cause us to change our route of entry. We think subcutaneous is still a viable approach for PRX012 transferrin-based moieties. We think that, in fact, it's the potency of PRX012 that provides us the ability to actually have a biological effect at a lower dose level setting, which obviously gives us the opportunity to have both a pharmacokinetic, as well as potency, advantage. I think that's something that you can evidence, for example, in the data set.

Speaker #1: We think subcutaneous is still viable approach for PRX12 transferrin-based amoides. We think that in fact, it's the potency of PRX12 that provides us the ability to actually have a biological effect at a lower dose level setting, which obviously gives us the opportunity to have both the pharmacokinetic as well as potency advantage.

Speaker #1: And I think that's something that you can evidence, for example, in the data set. We talked about the impact of PRX012—parent PRX012—on amyloid reduction.

Gene Kinney: We talked about the impact of PRX012, parent PRX012, on amyloid reduction, and how that was quite robust, particularly at the 400 mg dose level. I think you could compare that back to some of the earlier gantenerumab data, you know, which maybe was less robust by comparison. So that really speaks to the potency of PRX012, which we have always felt was a key element in terms of making sure that that is available to a subcutaneous route of administration. And obviously, we continue to believe that to be true. I don't know, Phil or Chad, if you have a comment that you'd like to make on this?

Speaker #1: And how that was quite robust, particularly at the 400-milligram dose level. I think you could compare that back to some of the earlier Gant and Neuromad data, which maybe was less robust by comparison.

Speaker #1: So that really speaks to the potency of PRX12, which we have always felt was a key element in terms of making sure that that is available to a subcutaneous route of administration.

Speaker #1: And obviously, we continue to believe that to be true. I don't know, Phil, or Chad, if you have a comment that you'd like to make on that.

Chad Swanson: I might just say one thing, Gene. So you actually touched on the potency, right? So clearly, we see pretty comparable and robust levels of reduction at 18 months with an antibody that is dosed a flat dose of 400, which is, you know, significantly less, I would say, than the 10 mg per kg that's in the clinic now. Because of that, and obviously, we don't know the answer to this, but I know you had a question about heme toxicity. And because of the potency, it's possible that we could dose at lower levels and see similar effects to what trontinemab saw, for instance. If that's the case, there is potential perhaps to minimize risk in terms of these non-ARIA AEs, i.e., you know, anemia or others.

Speaker #3: I might just say one thing, Gene. So you actually touched on the potency, right? So clearly we see pretty comparable and robust levels of reduction at 18 months.

Speaker #3: With an antibody that is dosed at a flat dose of 400, which is significantly less, I would say, than the 10 meg per keg that's in the clinic now.

Speaker #3: Because of that, and obviously we don't know the answer to this, but I know you had a question about heme toxicity. And because of the potency, it's possible that we could dose at lower levels and see similar effects to what trontinimab saw, for instance.

Speaker #3: If that's the case, there is potential, perhaps, to minimize risk in terms of these non-ARIA AEs—i.e., anemia or others. So I think there's potential there.

Chad Swanson: So I think there's potential there, and we just, you know, we have to do the study.

Speaker #3: We’d have to do the study.

Speaker #4: Thank you. That's very helpful.

[Analyst] (RBC Capital Markets): Thank you. That's very helpful.

[Company Representative] (RBC Capital Markets): Thank you. That's very helpful.

Speaker #2: Thank you, everyone. That completes our question and answer session. I'll now turn it over to Gene Kinney, CEO for Closing Remarks.

Operator: Thank you, everyone. That completes our question and answer session. I'll now turn it over to Gene Kinney, CEO, for closing remarks.

Speaker #1: Thank you, operator. And I want to thank you all for joining us on the call today. We appreciate your interest in Prothena and look forward to sharing further updates on our programs.

Gene Kinney: Thank you, operator, and I want to thank you all for joining us on the call today. We appreciate your interest in Prothena and look forward to sharing further updates on our progress.

Operator: Thank you for your participation in today's conference call. This concludes the presentation. You may now disconnect. Good day.

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