PROTHENA CORP PUBLIC LTD CO
For the period ended Jun 30, 2025. Filed Aug 4, 2025.
View on SEC.govAbout this filing
A company's report for each of its first three quarters. The financial statements are not audited. It shows how the business has moved since the last annual report, and what management says changed.
Jun 30, 2025 · Filed Aug 4, 2025
PRTA$7.97+1.0%Stored close · as of Nov 6, 2026
What changed in Management’s Discussion and Analysis?
Read the current filingPrevious report: 10-Q
Period ended 2025-03-31; filed 2025-05-08.
0001559053-25-000023
Item 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONSCurrent report: 10-Q
Period ended 2025-06-30; filed 2025-08-04.
0001559053-25-000031
Item 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONSThe baseline is this issuer’s latest earlier reporting period of the same form that was filed before the current report. A previous 10-Q is a different quarter, not a year-over-year comparison. Amendments are excluded.
Compared 119 previous paragraphs and 116 current paragraphs.
69 unchanged; 34 reworded; 13 added; 15 removed; 1 previous and 0 current paragraphs rearranged.
Tables are not compared: 8 previous and 12 current tables excluded. Dates, whitespace, punctuation and numbering changes are ignored; changes to financial figures remain significant.
A changed paragraph is not evidence that risk increased or decreased. An unchanged paragraph does not establish that risk stayed the same.
Added paragraphs (13)
Current report
In June 2025, Roche announced that it will advance prasinezumab into Phase 3 development for early-stage Parkinson’s disease. Roche cited that the data from the Phase 2b PADOVA study and longer-term follow-up data suggest clinical benefit on top of symptomatic treatment in early-stage Parkinson’s disease.
Current report
Phase 1 Clinical Trials
Current report
In the second quarter of 2025, BMS initiated a Phase 1 clinical trial to assess drug levels, tolerability and absolute biological availability of single subcutaneous dose of BMS-986446 in healthy participants. This is a Phase 1, randomized, open-label, parallel, single-dose clinical trial to assess the pharmacokinetics, tolerability, and absolute bioavailability of subcutaneous administration of BMS-986446, an anti-MTBR tau monoclonal antibody, in approximately 46 healthy participants.
Current report
Discontinuation of Birtamimab Development
Current report
Workforce Reduction
Current report
In June 2025, we announced an approximate 63% reduction in our workforce to substantially reduce our operating costs to those necessary to support our remaining wholly-owned programs, obligations to partnered programs, and anticipated business development activities.
Current report
Restructuring Costs
Current report
In June 2025, we commenced a restructuring plan following our decision in May 2025 to discontinue further development of birtamimab. We have incurred aggregate restructuring charges of approximately $32.6 million for thethree and six months ended June 30, 2025.
Current report
Restructuring charges incurred under this plan primarily consist of employee termination benefits in connection with the reduction in force announced in June 2025 and contract termination costs. Employee termination benefits include severance costs, employee-related benefits, and noncash share-based compensation expense related to the acceleration of the vesting of certain stock options. Substantially all of the cash payments are expected to be paid out by the end of the fourth quarter of 2025. We may also incur additional costs not currently contemplated due to events that may occur as a result of, or that are associated with, the restructuring plan. See Note 11, “Restructuring” to the Condensed Consolidated Financial Statements for more information.
Current report
n/m = not meaningful
Current report
On July 4, 2025, the United States enacted tax reform legislation through the One Big Beautiful Bill Act. As a result of the enactment of the legislation, the Company expects a decrease to its tax expense during the remainder of the year, primarily related to changes in the capitalization requirements of domestic research and development activities.
Current report
Six Months Ended June 30, 2024
Current report
(3) Includes cash obligations under our restructuring plan. For additional information, see Note 11, “Restructuring” to our Condensed Consolidated Financial Statements.
Removed paragraphs (15)
Previous report
About Birtamimab and AL Amyloidosis
Previous report
Birtamimab is an investigational humanized antibody that targets toxic misfolded light chain that causes organ dysfunction and failure in patients with AL amyloidosis. AL amyloidosis is a rare, progressive, and typically fatal disease where immunoglobulin light chain proteins produced by clonal plasma cells misfold, aggregate, and deposit as amyloid in vital organs. These toxic aggregates and amyloid deposits cause progressive damage and failure of vital organs, including the heart.
Previous report
Birtamimab binds to both soluble and insoluble amyloid aggregates in multiple organs and promotes the clearance of amyloid deposits via phagocytosis. This anti-amyloid mechanism of action broadly targets misfolded kappa and lambda light chain to clear deposited amyloid that causes organ dysfunction and failure in patients with AL amyloidosis. Birtamimab is the only investigational therapeutic that has demonstrated a significant survival benefit in a randomized clinical trial in patients with Mayo Stage IV AL amyloidosis. Birtamimab has been granted Fast Track Designation by the U.S. Food and Drug Administration (FDA) for the treatment of Mayo Stage IV patients with AL amyloidosis to reduce the risk of mortality and has been granted Orphan Drug Designation by both the FDA and European Medicines Agency (EMA).
Previous report
It is estimated that 200,000 to 400,000 patients globally suffer from this rare disease, with approximately 60,000 to 120,000 (or 30%) of those patients being categorized as Mayo Stage IV. Patients categorized at diagnosis as Mayo Stage IV have poor outcomes with current standard-of-care that aims to reduce the production of new protein but does not directly target and clear the toxic amyloid that deposits in organs. There are currently no approved treatments for AL amyloidosis that have demonstrated a survival benefit in a randomized clinical trial, and there is an urgent unmet medical need for therapies that improve survival in patients at risk for early mortality due to amyloid deposition.
Previous report
Clinical Development Program for Birtamimab
Previous report
Birtamimab reacts with a “cryptic” epitope that is exposed on misfolded kappa and lambda light chains that misfold and form amyloid. The epitope is well defined and highly conserved in light chains and exposed from early stages of aggregation throughout amyloid. Preclinical research has demonstrated that birtamimab binds to both soluble and insoluble aggregated kappa and lambda immunoglobulin light chain by recognizing this epitope that is exposed at the earliest stages of abnormal light chain misfolding and through aggregation of deposited amyloid. Our extensive preclinical findings and publications describe two proposed mechanisms of action for birtamimab: binding and neutralization of soluble toxic light chain aggregates, and clearance of amyloid deposits by phagocytosis.
Previous report
In multiple clinical trials, birtamimab has been shown to be generally safe and well tolerated and has been evaluated in 302 patients receiving monthly intravenous infusions (including 294 patients who received the recommended 24 mg/kg dose), for an average of approximately 15 months.
Previous report
Confirmatory Phase 3 AFFIRM-AL Clinical Trial Design under SPA Agreement with FDA
Previous report
Based on further analyses of data from the VITAL clinical trial and multiple in-depth discussions with the FDA, Prothena announced plans in February 2021, to advance birtamimab into the confirmatory Phase 3 AFFIRM-AL clinical trial in patients with Mayo Stage IV AL amyloidosis. AFFIRM-AL is a registration-enabling Phase 3 clinical trial that is being conducted with a primary endpoint of time to all-cause mortality at p<0.10 under a Special Protocol Assessment (SPA) agreement with the FDA. AFFIRM-AL topline trial results are expected in the second quarter of 2025.
Previous report
AFFIRM-AL is an ongoing global, multi-center, double-blind, placebo-controlled, 2:1 randomized, time-to-event trial expected to enroll up to 220 newly diagnosed, treatment naïve patients with AL amyloidosis categorized as Mayo Stage IV. Patients receive 24 mg/kg of birtamimab or placebo by intravenous infusion every 28 days, with all patients receiving concurrent standard of care chemotherapy in accordance with the institutional standard of care which includes a bortezomib-containing chemotherapy regimen such as cyclophosphamide, bortezomib, and dexamethasone (CyBorD). The initiation of daratumumab treatment at randomization is allowed at the discretion of the investigator. The trial has been designed to evaluate the primary endpoint of time to all-cause mortality with a significance level of p<0.10. Secondary endpoints will assess change from baseline to month 9 in functional capacity as measured by 6MWT distance and quality of life as measured by SF-36v2 PCS.
Previous report
Phase 3 VITAL Clinical Trial Results
Previous report
In June 2023, we announced that results from the Phase 3 VITAL clinical trial were published in Blood, a journal of the American Society of Hematology (“ASH”). The published data demonstrate that in a post hoc analysis of patients with Mayo Stage IV AL amyloidosis, a statistically significant survival benefit of 74 percent was observed for those treated with birtamimab plus standard of care (“SOC”) versus 49 percent in patients on placebo plus SOC at 9 months (HR 0.413, p=0.021).
Previous report
The article, entitled “Birtamimab plus standard of care in light chain amyloidosis: the phase 3 randomized placebo-controlled VITAL clinical trial”, also demonstrated that patients with Mayo Stage IV AL amyloidosis treated with birtamimab had statistically significant improvements over placebo in a post hoc assessment of two key secondary endpoints, quality of life (assessed with the Short Form-36 version 2 physical component score, SF-36v2 PCS) and cardiac function (assessed with the 6-minute walk test). Patients treated with birtamimab showed a slower decline in quality of life with a mean decrease of 0.75 in the SF-36v2 PCS at 9 months compared to a mean decrease of 5.40 in the SF-36v2 PCS for patients on placebo at 9 months (a mean difference of 4.65 favoring birtamimab; p=0.046). Patients treated with birtamimab after 9 months demonstrated an increase in mean distance of 15.22 meters in the 6-minute walk test, compared to a decrease in mean distance of 21.15 meters for patients on placebo (a mean difference of 36.37 meters favoring birtamimab; p=0.022).
Previous report
Phase 1 Clinical Trial
Previous report
Three Months Ended March 31, 2024
Reworded paragraphs (34)
Previous wording
PRX012, which targets amyloid beta (Aβ), and PRX123, a novel dual Aβ-tau vaccine. Our partnered programs include prasinezumab for the potential treatment of Parkinson’s disease and other related synucleinopathies that targets alpha-synuclein in collaboration with Roche. In addition, we have partnered BMS-986446 (formerly PRX005) for the potential treatment for Alzheimer’s disease that targets tau and PRX019 for the potential treatment of neurodegenerative diseases with an undisclosed target in two separate license agreements with Bristol Myers Squibb (BMS). We are also entitled to certain potential milestone payments pursuant to our share purchase agreement with Novo Nordisk pertaining to our ATTR amyloidosis business (inclusive of coramitug, formerly PRX004).
Current wording
Fueled by our deep scientific expertise built over decades of research, we are advancing a pipeline of therapeutic candidates for a number of indications and novel targets for which our ability to integrate scientific insights around neurological dysfunction and the biology of misfolded proteins can be leveraged. Our wholly-owned programs include a portfolio of programs for the potential treatment of Alzheimer’s disease including PRX012, which targets amyloid beta (Aβ), and PRX123, a novel dual Aβ-tau vaccine. Our partnered programs include prasinezumab for the potential treatment of Parkinson’s disease and other related synucleinopathies that targets alpha-synuclein in collaboration with Roche. In addition, we have partnered BMS-986446 (formerly PRX005) for the potential treatment for Alzheimer’s disease that targets tau and PRX019 for the potential treatment of neurodegenerative diseases with an undisclosed target in two separate license agreements with Bristol Myers Squibb (BMS). We are also entitled to certain potential milestone payments pursuant to our share purchase agreement with Novo Nordisk pertaining to our ATTR amyloidosis business (inclusive of coramitug, formerly PRX004).
Previous wording
In December 2024, topline results were announced from the Phase 2b clinical trial (PADOVA) conducted by partner Roche investigating prasinezumab in 586 people with early-stage Parkinson’s disease, treated for a minimum of 18 months while on stable symptomatic treatment. In April 2025, results from the Phase 2b PADOVA trial were presented for the first time in an oral presentation by Roche at the International Conference on Alzheimer’s and Parkinson’s Diseases (“AD/PD 2025”). Prasinezumab showed potential clinical effect in the primary endpoint of time to confirmed motor progression, as assessed by ≥5 point increase in Movement Disorder Society – Unified Parkinson’s Disease Rating Scale (“MDS-UPDRS”) Part III score from baseline, with a HR=0.84 [0.69-1.01] and p=0.0657. The effect of prasinezumab was more pronounced in a pre-specified analysis in the population treated with levodopa (75% of participants), HR=0.79 [0.63-0.99] and nominal p=0.0431. Pre-specified supplementary covariate-adjusted analyses of these endpoints demonstrated nominally significant effects on the primary endpoint (HR=0.81 [0.67-0.98]; nominal p=0.0334) and in the levodopa subgroup (HR=0.76 [0.61-0.95]; nominal p=0.0175). Covariates used for adjustment: medication at baseline, H&Y stage, DaT-SPECT, age, sex, baseline dependent parameter. Consistent positive trends across multiple secondary and exploratory clinical endpoints were also observed, in addition to a potential biological effect of prasinezumab on MRI biomarkers. Prasinezumab continues to be well tolerated and no new safety signals were observed in the study.
Current wording
In December 2024, topline results were announced from the Phase 2b clinical trial (PADOVA) conducted by partner Roche investigating prasinezumab in 586 people with early-stage Parkinson’s disease, treated for a minimum of 18 months while on stable symptomatic treatment. In April 2025, results from the Phase 2b PADOVA trial were presented for the first time in an oral presentation by Roche at the International Conference on Alzheimer’s and Parkinson’s Diseases (“AD/PD 2025”). Prasinezumab showed potential clinical effect in the primary endpoint of time to confirmed motor progression, as assessed by ≥5 point increase in Movement Disorder Society – Unified Parkinson’s Disease Rating Scale (“MDS-UPDRS”) Part III score from baseline, with a HR=0.84 [0.69-1.01] and p=0.0657. The effect of prasinezumab was more pronounced in a pre-specified analysis in the population treated with levodopa (75% of participants), HR=0.79 [0.63-0.99] and nominal p=0.0431. Pre-specified supplementary covariate-adjusted analyses of these endpoints demonstrated nominally significant effects on the primary endpoint (HR=0.81 [0.67-0.98]; nominal p=0.0334) and in the levodopa subgroup (HR=0.76 [0.61-0.95]; nominal p=0.0175). Covariates used for adjustment: medication at baseline, H&Y stage, DaT-SPECT, age, sex, baseline dependent parameter. Consistent positive trends across multiple secondary and exploratory clinical endpoints were also observed. Positive trends towards reduced motor progression at 104 weeks (two years) were observed, showing 30-40% relative reduction versus placebo across the overall and levodopa-treated populations. The PADOVA study also provided the first biomarker evidence of prasinezumab impacting the underlying disease biology. Prasinezumab continues to be well tolerated and no new safety signals were observed in the study.
Previous wording
Prasinezumab is the first anti-alpha synuclein antibody to advance into late-stage development. In March 2022, results from the analysis of part 2 of the Phase 2 PASADENA trial of prasinezumab were presented in an oral presentation by Roche at the International Conference on Alzheimer’s and Parkinson’s Diseases (“AD/PD 2022”). Results showed that participants with Parkinson’s disease who were treated with prasinezumab for two years (early-start group) showed slower decline of MDS-UPDRS Part III scores relative to participants treated with placebo in the first year and prasinezumab in the second year (delayed-start group), further supporting a potential effect on delaying motor progression in patients. In October 2024, Roche published results in Nature Medicine from the long term open-label extension of the PASADENA trial, which compared the prasinezumab population with a propensity score-balanced cohort of real-world data (“RWD”) Parkinson’s Progression Markers Initiative (“PPMI”). The data suggests that prasinezumab continued to show reduced motor and functional progression in prazinezumab-treated individuals with early-stage Parkinson’s disease compared to a real-world data arm on MDS-UPDRS Part III score (clinician rated motor examination) OFF and ON symptomatic medication state and MDS-UPDRS Part II score (patient-reported motor experiences of daily living). The Phase 2 PASADENA and Phase 2b PADOVA open-label extension studies will continue in order to further explore the observed effects in both studies. Given the high level of unmet need for these patients, Roche is further evaluating study data and will work together with health authorities to determine next steps.
Current wording
Prasinezumab is the first anti-alpha synuclein antibody to advance into late-stage development. In March 2022, results from the analysis of part 2 of the Phase 2 PASADENA trial of prasinezumab were presented in an oral presentation by Roche at the International Conference on Alzheimer’s and Parkinson’s Diseases (“AD/PD 2022”). Results showed that participants with Parkinson’s disease who were treated with prasinezumab for two years (early-start group) showed slower decline of MDS-UPDRS Part III scores relative to participants treated with placebo in the first year and prasinezumab in the second year (delayed-start group), further supporting a potential effect on delaying motor progression in patients. In October 2024, Roche published results in Nature Medicine from the long term open-label extension of the PASADENA trial, which compared the prasinezumab population with a propensity score-balanced cohort of real-world data (“RWD”) Parkinson’s Progression Markers Initiative (“PPMI”). The data suggests that prasinezumab continued to show reduced motor and functional progression in prazinezumab-treated individuals with early-stage Parkinson’s disease compared to a real-world data arm on MDS-UPDRS Part III score (clinician rated motor examination) OFF and ON symptomatic medication state and MDS-UPDRS Part II score (patient-reported motor experiences of daily living). The Phase 2 PASADENA and Phase 2b PADOVA open-label extension studies will continue in order to further explore the observed effects in both studies.
Previous wording
A Phase 2 clinical trial of coramitug in approximately 99 patients with ATTR amyloidosis with cardiomyopathy is being conducted by Novo Nordisk (NCT05442047).
Current wording
A Phase 2 clinical trial of coramitug in 105 patients with ATTR amyloidosis with cardiomyopathy was conducted by Novo Nordisk (NCT05442047).
Previous wording
In the first quarter of 2024, BMS advanced the anti-tau program BMS-986446 with the initiation of a Phase 2 clinical trial (NCT06268886). This is a randomized, double-blind, placebo-controlled, global, Phase 2 clinical trial designed to evaluate the efficacy, safety, and tolerability of BMS-986446, an anti-MTBR tau monoclonal antibody, in approximately 475 participants with early Alzheimer's disease. Participants will be randomized into one of three treatment arms including placebo, BMS-986446 Dose A, and BMS-986446 Dose B. The primary outcome measure is mean change from baseline to week 76 in Clinical Dementia Rating Scale Sum of Boxes (“CDR-SB”).
Current wording
In the first quarter of 2024, BMS advanced the anti-tau program BMS-986446 with the initiation of a Phase 2 clinical trial (NCT06268886). This is a randomized, double-blind, placebo-controlled, global, Phase 2 clinical trial designed to evaluate the efficacy, safety, and tolerability of BMS-986446, an anti-MTBR tau monoclonal antibody, in approximately 310 participants with early Alzheimer's disease. Participants will be randomized into one of three treatment arms including placebo, BMS-986446 Dose A, and BMS-986446 Dose B. The primary outcome measure is change from baseline in brain tau deposition as measured by tau positron emission tomography (PET) at 76 weeks.
Previous wording
We are advancing our lead candidate, PRX012, as a next-generation approach for subcutaneous administration to address the unmet need of millions of patients with presymptomatic or early symptomatic Alzheimer's disease. In March 2022, we announced the FDA clearance of the IND for PRX012 and the initiation of a Phase 1 single ascending dose trial to investigate the safety, tolerability, immunogenicity, and pharmacokinetics of PRX012 in both healthy volunteers and patients with Alzheimer’s disease. In April 2022, we announced that the FDA granted Fast Track designation for PRX012 for the treatment of Alzheimer’s disease. The FDA’s Fast Track designation program is designed to expedite the development and review of drugs intended to treat a serious condition, such as Alzheimer’s disease, with evidence demonstrating the potential to address an unmet medical need. In January 2024, we announced that topline Phase 1 data from the single ascending dose trial and the initial multiple dose cohort (70 mg) supports single-injection once-monthly subcutaneous treatment and dose escalation. The ongoing Phase 1 trial continues as planned and we expect to report multiple clinical readouts starting in mid-2025 and continuing throughout the year.
Current wording
We are advancing our lead candidate, PRX012, as a next-generation approach for subcutaneous administration to address the unmet need of millions of patients with presymptomatic or early symptomatic Alzheimer's disease. In March 2022, we announced the FDA clearance of the IND for PRX012 and the initiation of a Phase 1 single ascending dose trial to investigate the safety, tolerability, immunogenicity, and pharmacokinetics of PRX012 in both healthy volunteers and patients with Alzheimer’s disease. In April 2022, we announced that the FDA granted Fast Track designation for PRX012 for the treatment of Alzheimer’s disease. The FDA’s Fast Track designation program is designed to expedite the development and review of drugs intended to treat a serious condition, such as Alzheimer’s disease, with evidence demonstrating the potential to address an unmet medical need. In January 2024, we announced that topline Phase 1 data from the single ascending dose trial and the initial multiple dose cohort (70 mg) supports single-injection once-monthly subcutaneous treatment and dose escalation. The ongoing Phase 1 trial continues as planned and we expect to report initial data in August 2025. Following the data from the Phase 1 ASCENT clinical trials, we will look to advance PRX012 through non-dilutive and capital efficient structures.
Previous wording
In January 2024, we announced that the FDA has cleared the IND application for PRX123 and granted PRX123 Fast Track designation.
Current wording
In January 2024, we announced that the FDA has cleared the IND application for PRX123 and granted PRX123 Fast Track designation. We expect to advance PRX123 through non-dilutive and capital efficient structures.
Previous wording
Birtamimab for the Potential Treatment of AL Amyloidosis
Current wording
In May 2025, we announced the discontinuation of development of birtamimab, an investigational monoclonal antibody for the potential treatment of AL amyloidosis, based on the results from the Phase 3 AFFIRM-AL clinical trial for birtamimab, which did not meet its primary or secondary endpoints.
Previous wording
There were no significant changes to our critical accounting policies and estimates during the three months ended March 31, 2025, from the critical accounting policies and estimates disclosed in Management's Discussion and Analysis of Financial Condition and Results of Operations in our 2024 Form 10-K.
Current wording
There were no significant changes to our critical accounting policies and estimates during the six months ended June 30, 2025, from the critical accounting policies and estimates disclosed in Management's Discussion and Analysis of Financial Condition and Results of Operations in our 2024 Form 10-K.
Previous wording
Except as described in Note 2 to the Condensed Consolidated Financial Statements under the heading “Recent Accounting Pronouncements”, there have been no new accounting pronouncements or changes to accounting pronouncements during the three months ended March 31, 2025, as compared to the recent accounting pronouncements described in our 2024 Form 10-K, that are of significance or potential significance to us.
Current wording
Except as described in Note 2 to the Condensed Consolidated Financial Statements under the heading “Recent Accounting Pronouncements”, there have been no new accounting pronouncements or changes to accounting pronouncements during the six months ended June 30, 2025, as compared to the recent accounting pronouncements described in our 2024 Form 10-K, that are of significance or potential significance to us.
Previous wording
Comparison of three months ended March 31, 2025 and 2024
Current wording
Comparison of three and six months ended June 30, 2025 and 2024
Previous wording
Total revenue was $2.8 million and $0.1 million for the three months ended March 31, 2025, and 2024, respectively.
Current wording
Total revenue was $4.4 million and$132.0 million for the three months ended June 30, 2025 and 2024, respectively, and $7.2 million and $132.1 million for the six months ended June 30, 2025, and 2024, respectively.
Previous wording
Collaboration revenue was $2.8 million for the three months ended March 31, 2025, compared to nil for the three months ended March 31, 2024. Collaboration revenue for three months ended March 31, 2025 was related to the partial performance of our PRX019 Phase 1 Clinical Trial Obligation.
Current wording
Collaboration revenue was $4.4 million and $7.2 million for thethree and six months ended June 30, 2025, compared to$132.0 million and$132.0 million for thethree and six months ended June 30, 2024. Collaboration revenue forthree and six months ended June 30, 2025 was related to the partial performance of our PRX019 Phase 1 Clinical Trial Obligation. Collaboration revenue of$132.0 million for thethree and six months ended June 30, 2024, was related to revenue recognized under our Collaboration Agreement with BMS of which,$107.0 million was from the PRX019 Global License Agreement and PRX019 Phase 1 Clinical Trial Obligation and$25.0 million was related to BMS’s material rights for the US Rights and Global Rights for the TDP-43 Collaboration Target that were fulfilled on May 24, 2024 as a result of the expiration of the research term of the Collaboration Agreement.
Previous wording
As of March 31, 2025, the Company has $9.5 million of deferred revenue related to the remaining performance obligations under the PRX019 Global License Agreement relatedto PRX019 Phase 1 Clinical Trial Obligations. See Note 7, “Significant Agreements” to the Condensed Consolidated Financial Statements regarding the Collaboration Agreement with BMS for more information.
Current wording
As of June 30, 2025, the Company has $5.1 million of deferred revenue related to the remaining performance obligations under the PRX019 Global License Agreement relatedto PRX019 Phase 1 Clinical Trial Obligations. See Note 7, “Significant Agreements” to the Condensed Consolidated Financial Statements regarding the Collaboration Agreement with BMS for more information.
Previous wording
License and intellectual property revenue for the three months ended March 31, 2025, and 2024 included $50,000 in each period, respectively, in license fees recognized under the License Agreement entered into on March 1, 2020, between the Company's wholly owned subsidiary, Prothena Biosciences Limited, and F. Hoffmann-La Roche Ltd.
Current wording
License and intellectual property revenue for the six months ended June 30, 2025, and 2024 included $50,000 in each period, respectively, in license fees recognized under the License Agreement entered into on March 1, 2020, between the Company's wholly owned subsidiary, Prothena Biosciences Limited, and F. Hoffmann-La Roche Ltd.
Previous wording
Total operating expenses consist of R&D expenses, general and administrative (“G&A”) expenses. Our operating expenses were$68.4 million and $81.6 million for thethree months ended March 31, 2025, and 2024, respectively.
Current wording
Total operating expenses consist of R&D expenses, general and administrative (“G&A”) expenses, and restructuring costs. Our operating expenses were $89.0 million and $73.6 million three months ended June 30, 2025 and 2024, respectively, and $157.4 million and $155.2 million for thesix months ended June 30, 2025, and 2024, respectively.
Previous wording
Our R&D expense decreased by $13.3 million for the three months ended March 31, 2025, compared to the same period in the prior year. The decrease for the three months ended March 31, 2025, compared to the same period in the prior year, was primarily due to lower clinical trial expenses primarily related to the PRX012, lower manufacturing expense and lower personnel expenses.
Current wording
Our R&D expense decreased by $17.0 million or 30% for the three months ended June 30, 2025 and decreased by $30.3 million or 25%for the six months ended June 30, 2025, compared to the same periods in the prior year. The decrease for the three and six months ended June 30, 2025, compared to the same periods in the prior year, was primarily due to lower clinical trial expenses primarily related to PRX012, lower manufacturing expense and lower personnel expenses.
Previous wording
The following table sets forth the R&D expenses for our major programs (specifically, any active program with successful first dosing in a Phase 1 clinical trial and have material expenditures in the periods presented), which were birtamimab, PRX012, PRX019, and other R&D expenses for thethree months ended March 31, 2025, and 2024, (in thousands):
Current wording
The following table sets forth the R&D expenses for our major programs (specifically, programs with successful first dosing in a Phase 1 clinical trial and have material expenditures in the periods presented), which were birtamimab, PRX012, PRX019, and other R&D expenses for the three and six months ended June 30, 2025, and 2024, (in thousands):
Previous wording
Our G&A expenses increased by $0.1 million for the three months ended March 31, 2025, compared to the same period in the prior.
Current wording
Our G&A expenses decreasedby $0.2 million or 1% for the three months ended June 30, 2025 and decreased by $0.1 million for thesix months ended June 30, 2025, compared to the same periods in the prior.
Previous wording
Interest income decreased by $2.8 million for the three months ended March 31, 2025, compared to the same period in the prior year primarily due to lower interest income from our cash and money market accounts resulting from lower yields and lower cash balances.
Current wording
Interest income decreasedby $2.7 million or 42%for the three months ended June 30, 2025 and decreased by $5.5 million or 41%for the six months ended June 30, 2025, compared to the same periods in the prior year primarily due to lower interest income from our cash and money market accounts resulting from lower yields and lower cash balances.
Previous wording
Other expense, net for the three months ended March 31, 2025, was primarily foreign exchange losses from transactions with vendors denominated in euros.
Current wording
Other expense, net for thethree and six months ended June 30, 2025, was primarily foreign exchange losses from transactions with vendors denominated in euros.
Previous wording
The benefit from income taxes decreased by $1.0 millionor 46% for the three months ended March 31, 2025, compared to the same period in the prior year. The decline in benefit from income taxes for the three months ended March 31, 2025, compared to the same period in the prior year, was primarily due to a decrease in the amount capitalized, net of amortization, as deferred tax assets related to Section 174 R&D Capitalization.
Current wording
Income tax expense increasedby $46.8 millionfor the three months ended June 30, 2025 and increasedby $47.9 millionfor the six months ended June 30, 2025, compared to the same periods in the prior year. The increase in income taxes expense for the three and six months ended June 30, 2025, compared to the same periods in the prior year, was primarily due to recording a valuation allowance for the federal deferred tax assets primarily relating to share-based compensation and capitalized R&D related to Section 174 R&D Capitalization during the three and six months ended June 30, 2025.
Previous wording
Working capital was$387.7 million as of March 31, 2025, a decrease of $49.2 million from working capital of$436.9 million as of December 31, 2024. This decrease in working capital during the three months ended March 31, 2025, was primarily attributable to cash used in operating activities of $53.4 million.
Current wording
Working capital was$317.7 million as of June 30, 2025, a decrease of $119.2 million from working capital of$436.9 million as of December 31, 2024. This decrease in working capital during the six months ended June 30, 2025, was primarily attributable to cash used in operating activities of $99.7 million.
Previous wording
As of March 31, 2025, we had $417.9 million in cash and cash equivalents. Based on our current business plans, we believe that our existing cash and cash equivalents at March 31, 2025 are sufficient to meet our obligations for at least the next twelve months. To operate beyond such period, or if we elect to increase our spending on research and development programs significantly above current long-term plans or enter into potential licenses and/or other acquisitions of complementary technologies, products or companies, we may need additional capital. Additionally, in order to develop and obtain regulatory approval for our potential products we will need to raise substantial additional capital. We expect to continue to finance future capital needs that exceed our existing cash and cash equivalents, payments pursuant to our agreements with Roche, BMS, and Novo Nordisk, and, to the extent necessary, other collaboration agreements with corporate partners, or other arrangements, and through proceeds from public or private equity or debt financings, and loans, including pursuant to the Amended Distribution
Current wording
As of June 30, 2025, we had $371.4 million in cash and cash equivalents. Based on our current business plans, we believe that our existing cash and cash equivalents at June 30, 2025 are sufficient to meet our obligations for at least the next twelve months. To operate beyond such period, or if we elect to increase our spending on research and development programs significantly above current long-term plans or enter into potential licenses and/or other acquisitions of complementary technologies, products or companies, we may need additional capital. Additionally, in order to develop and obtain regulatory approval for our potential products we will need to raise substantial additional capital. We expect to continue to finance future capital needs that exceed our existing cash and cash equivalents, payments pursuant to our agreements with Roche, BMS, and Novo Nordisk, and, to the extent necessary, other collaboration agreements with corporate partners, or other arrangements, and through proceeds from public or private equity or debt financings, and loans, including pursuant to the Amended Distribution Agreement (See Note 8, “Shareholders’ Equity” to the Condensed Consolidated Financial Statements for more information).
Previous wording
Agreement (See Note 8, “Shareholders’ Equity” to the Condensed Consolidated Financial Statements for more information). We cannot assume that such additional financings will be available on acceptable terms, if at all, and such financings may only be available on terms dilutive to our shareholders.
Current wording
We cannot assume that such additional financings will be available on acceptable terms, if at all, and such financings may only be available on terms dilutive to our shareholders.
Previous wording
In managing our liquidity needs in Ireland, we do not rely on unrepatriated earnings as a source of funds. As of March 31, 2025, $264.9 million of our outstanding cash and cash equivalents related to U.S. operations are considered permanently reinvested. We do not intend to repatriate these funds. However, if these funds were repatriated back to Ireland, we would incur a withholding tax from the dividend distribution.
Current wording
In managing our liquidity needs in Ireland, we do not rely on unrepatriated earnings as a source of funds. As of June 30, 2025, $264.4 million of our outstanding cash and cash equivalents related to U.S. operations are considered permanently reinvested. We do not intend to repatriate these funds. However, if these funds were repatriated back to Ireland, we would incur a withholding tax from the dividend distribution.
Previous wording
The adequacy of our cash resources depends on many assumptions, including assumptions with respect to our expenses. These assumptions may prove to be wrong, and we could use our available capital resources sooner than we currently expect. Because of the numerous risks and uncertainties associated with the development and commercialization of our product candidates, we are unable to estimate the amounts of increased capital outlays and operating expenses associated with completing the development of our product candidates. Our future capital requirements will depend on numerous factors, including, without limitation, the timing of initiation, progress, results and costs of our clinical trials; the results of our research and nonclinical studies; the costs of clinical manufacturing and of establishing commercial manufacturing arrangements; the costs of preparing, filing and prosecuting patent applications and maintaining, enforcing and defending intellectual property-related claims; the costs and timing of capital asset purchases; our ability to establish research collaborations, strategic collaborations, licensing or other arrangements; the costs to satisfy our obligations under current and potential future collaborations; the costs of any in-licensing transactions; and the timing, receipt, and amount of revenues or royalties, if any, from any approved drug candidates.
Current wording
The adequacy of our cash resources depends on many assumptions, including assumptions with respect to our expenses. These assumptions may prove to be wrong, and we could use our available capital resources sooner than we currently expect. Because of the numerous risks and uncertainties associated with the development of our product candidates, we are unable to estimate the amounts of increased capital outlays and operating expenses associated with completing the development of our product candidates. Our future capital requirements will depend on numerous factors, including, without limitation, the timing of initiation, progress, results and costs of our clinical trials; the results of our research and nonclinical studies; the costs of clinical manufacturing; the costs of preparing, filing and prosecuting patent applications and maintaining, enforcing and defending intellectual property-related claims; the costs and timing of capital asset purchases; our ability to establish research collaborations, strategic collaborations, licensing or other arrangements; the costs to satisfy our obligations under current and potential future collaborations; the costs of any in-licensing transactions; and the timing, receipt, and amount of revenues or royalties, if any, from any approved drug candidates.
Previous wording
Net cash used in operating activities was$53.4 million for the three months ended March 31, 2025, which was primarily due to ongoing research and development activities and general and administrative expenses to support those activities for a total of$68.4 million in operating expenses (adjusted to exclude non-cash charges of approximately$10.2 million) partially offset byinterest income on investments of$4.3 million.
Current wording
Net cash used in operating activities was$99.7 million for the six months ended June 30, 2025, which was primarily due to ongoing research and development activities, general and administrative expenses to support those activities (adjusted to exclude non-cash charges for share-based compensation expense) partially offset byinterest income on investments.
Previous wording
Net cash used in investing activities was $42 thousand for thethree months ended March 31, 2025, which primarily consisted of expenditures to purchase property and equipment.
Current wording
Net cash used in investing activities was $128 thousand for thesix months ended June 30, 2025, which primarily consisted of expenditures to purchase property and equipment.
Previous wording
Net cash used in financing activities was$48 thousand for thethree months ended March 31, 2025, which primarily consisted of expenditures related to our at-the-market offering.
Current wording
Net cash used in financing activities was$122 thousand for thesix months ended June 30, 2025, which primarily consisted of expenditures related to our at-the-market offering.
Previous wording
Refer to “Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations — Liquidity and Capital Resources” in our first quarter 2024 Quarterly Report on Form 10-Q for a discussion of the cash flows for the three months ended March 31, 2024.
Current wording
Refer to “Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations — Liquidity and Capital Resources” in our second quarter 2024 Quarterly Report on Form 10-Q for a discussion of the cash flows for the six months ended June 30, 2024.
Previous wording
Our contractual obligations as of March 31, 2025, consisted of minimum cash payments under operating leases of $11.3 million, purchase obligations of $15.6 million (of which $2.2 million is included in current liabilities), and contractual obligations under license agreements of $0.3 million (of which $10 thousand is included in current liabilities). Purchase obligations consist of non-cancelable purchase commitments to suppliers. Operating leases represent our future minimum rental commitments under our non-cancelable operating leases. For additional information regarding the timing for our contractual obligations see Note 6, “Commitments and Contingencies” to Condensed Consolidated Financial Statements.
Current wording
Our contractual obligations as of June 30, 2025, consisted of minimum cash payments under operating leases of $10.8 million, purchase obligations of $3.3 million (of which $2.6 million is included in current liabilities), obligations under our restructuring plan of $30.3 million (of which all of it is included in current liabilities), and contractual obligations under license agreements of $0.3 million). Purchase obligations consist of non-cancelable purchase commitments to suppliers. Operating leases represent our future minimum rental commitments under our non-cancelable operating leases. For additional information regarding the timing for our contractual obligations see Note 6, “Commitments and Contingencies” to Condensed Consolidated Financial Statements.
Previous wording
In October 2022, we entered into a noncancelable operating sublease to lease approximately 31,157 square feet of office and laboratory space in Brisbane, California. We are obligated to make lease payments totaling approximately $14.9 million over the lease term, which expires on September 30, 2028, unless terminated earlier. Of this obligation, approximately $11.3 million remains outstanding as of March 31, 2025
Current wording
In October 2022, we entered into a noncancelable operating sublease to lease approximately 31,157 square feet of office and laboratory space in Brisbane, California. We are obligated to make lease payments totaling approximately $14.9 million over the lease term, which expires on September 30, 2028, unless terminated earlier. Of this obligation, approximately $10.5 million remains outstanding as of June 30, 2025
Previous wording
In addition to the contractual obligations above, we also expect to have future material cash requirements related to ourclinical trials, discovery and pre-clinical programs, human capital and intellectual property. Assuming no significant change in our business, we expect the full year 2025 net cash used in operating and investing activities to be approximately $168 million to $175 million.
Current wording
In addition to the contractual obligations above, we also expect to have future material cash requirements related to our clinical trials, discovery and pre-clinical programs, human capital and intellectual property. Assuming no significant change in our business, we expect the full year 2025 net cash used in operating and investing activities to be approximately $170 million to $178 million.
Rearranged previous paragraphs (1)
Previous report — wording carried elsewhere
Fueled by our deep scientific expertise built over decades of research, we are advancing a pipeline of therapeutic candidates for a number of indications and novel targets for which our ability to integrate scientific insights around neurological dysfunction and the biology of misfolded proteins can be leveraged. Our wholly-owned programs include birtamimab for the potential treatment of AL amyloidosis, and a portfolio of programs for the potential treatment of Alzheimer’s disease including