Significant Agreements	6 Months Ended
Jun. 30, 2025
Collaborative Agreement [Abstract]
Significant Agreements	Significant Agreements Roche License Agreement In December 2013, the Company through its wholly owned subsidiary Prothena Biosciences Limited and Prothena Biosciences Inc entered into a License, Development, and Commercialization Agreement (the “License Agreement”) with F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. (together, “Roche”) to develop and commercialize certain antibodies that target α-synuclein, including prasinezumab, which are referred to collectively as “Licensed Products.” Upon the effectiveness of the License Agreement in January 2014, the Company granted to Roche an exclusive, worldwide license to develop, make, have made, use, sell, offer to sell, import and export the Licensed Products. The Company retained certain rights to conduct development of the Licensed Products and an option to co-promote prasinezumab in the U.S. During the term of the License Agreement, the Company and Roche will work exclusively with each other to research and develop antibody products targeting alpha-synuclein (or α-synuclein) potentially including incorporation of Roche’s proprietary Brain Shuttle™ technology to potentially increase delivery of therapeutic antibodies to the brain. The License Agreement provided for Roche making an upfront payment to the Company of $30.0 million, which was received in February 2014; making a clinical milestone payment of $15.0 million upon initiation of the Phase 1 clinical trial for prasinezumab, which was received in May 2014; making a clinical milestone payment of $30.0 million upon dosing of the first patient in the Phase 2 clinical trial for prasinezumab, which was achieved in June 2017; and making a clinical milestone payment of $60.0 million upon dosing of the first patient in the global Phase 2b PADOVA study for prasinezumab, which was achieved in May 2021. For prasinezumab, Roche is obligated to pay: •up to $290.0 million upon the achievement of development, regulatory, and various first commercial sales milestones; •up to $155.0 million upon achievement of U.S. commercial sales milestones; •up to $175.0 million upon achievement of ex-U.S. commercial sales milestones; and •tiered, high single-digit to high double-digit royalties in the teens based on U.S. and ex-U.S. annual net sales, subject to certain adjustments, with respect to the applicable Licensed Product. Roche bore 100% of the cost of conducting the research collaboration under the License Agreement during the research term, which expired December 31, 2017. In May 2021, the Company exercised its rights under the terms of License Agreement to receive potential U.S. commercial sales milestone and royalties, in lieu of a U.S. profit and loss share for prasinezumab in Parkinson’s disease. Thus, in the U.S., through May 28, 2021, the parties shared all development costs, all of which were allocated 70% to Roche and 30% to the Company, for prasinezumab in the Parkinson’s disease indication. If the Company opts in to participate in co-development and co-funding for any other Licensed Products and/or indications, the parties will share all development and commercialization costs, as well as profits, all of which will be allocated 70% to Roche and 30% to the Company. The Company initiated a Phase 1 clinical trial for prasinezumab in 2014. Following the Phase 1 clinical trial, Roche became primarily responsible for developing, obtaining and maintaining regulatory approval for and commercializing Licensed Products. Roche also became responsible for the clinical and commercial manufacture and supply of Licensed Products. In addition, the Company has an option under the License Agreement to co-promote prasinezumab in the U.S. in the Parkinson’s disease indication. If the Company exercises such option, it may also elect to co-promote additional Licensed Products in the U.S. approved for Parkinson’s disease. Outside the U.S., Roche will have responsibility for developing and commercializing the Licensed Products. Roche bears all costs that are specifically related to obtaining or maintaining regulatory approval outside the U.S. and will pay the Company a variable royalty based on annual net sales of the Licensed Products outside the U.S. The License Agreement continues on a country-by-country basis until the expiration of all payment obligations under the License Agreement. The License Agreement may also be terminated (i) by Roche at will after the first anniversary of the effective date of the License Agreement, either in its entirety or on a Licensed Product-by-Licensed Product basis, upon 90 days’ prior written notice to the Company prior to first commercial sale and 180 days’ prior written notice to Prothena after first commercial sale, (ii) by either party, either in its entirety or on a Licensed Product-by-Licensed Product or region-by-region basis, upon written notice in connection with a material breach uncured 90 days after initial written notice, and (iii) by either party, in its entirety, upon insolvency of the other party. The License Agreement may be terminated by either party on a patent-by-patent and country-by-country basis if the other party challenges a given patent in a given country. The Company’s rights to co-develop Licensed Products under the License Agreement will terminate if the Company commences certain studies for certain types of competitive products. The Company’s rights to co-promote Licensed Products under the License Agreement will terminate if the Company commences a Phase 3 study for such competitive products. The License Agreement cannot be assigned by either party without the prior written consent of the other party, except to an affiliate of such party or in the event of a merger or acquisition of such party, subject to certain conditions. The License Agreement also includes customary provisions regarding, among other things, confidentiality, intellectual property ownership, patent prosecution, enforcement and defense, representations and warranties, indemnification, insurance, and arbitration and dispute resolution. Performance Obligations As of June 30, 2025, and December 31, 2024, there were no remaining performance obligations under the License Agreement since the obligations related to research and development activities were only for the Phase 1 clinical trial and these obligations were delivered or performed. Milestone Accounting Under the License Agreement, the Company is eligible to receive certain milestone payments upon the achievement of development, regulatory and various first commercial sales milestones. Milestone payments are evaluated under ASC Topic 606. Factors considered in this determination included scientific and regulatory risk that must be overcome to achieve each milestone, the level of effort and investment required to achieve the milestone, and the monetary value attributed to the milestone. Accordingly, the Company estimates payments in the transaction price based on the most likely approach, which considers the single most likely amount in a range of possible amounts related to the achievement of these milestones. Additionally, milestone payments are included in the transaction price only when the Company can conclude it is probable that a significant revenue reversal will not occur in future periods when the milestone is achieved. The Company excludes the milestone payments and royalties in the initial transaction price calculation because such payments are considered to be variable considerations with constraint. Such milestone payments and royalties will be recognized as revenue once the Company can conclude it is probable that a significant revenue reversal will not occur in future periods. The clinical and regulatory milestones under the License Agreement after the point at which the Company could opt out are considered to be variable considerations with constraint due to the fact that active participation in the development activities that generate the milestones is not required under the License Agreement, and the Company can opt out of these activities. There are no refunds or claw-back provisions and the milestones are uncertain of occurrence even after the Company has opted out. Based on this determination, these milestones will be recognized when the Company can conclude it is probable that a significant revenue reversal will not occur in future periods. Roche did not achieve any milestones under the License Agreement during the three and six months ended June 30, 2025 and 2024, respectively. Collaboration Agreement with Bristol Myers Squibb Overview On March 20, 2018, the Company, through its wholly owned subsidiary Prothena Biosciences Limited (“PBL”), entered into a Master Collaboration Agreement (the “Collaboration Agreement”) with Celgene Switzerland LLC (“Celgene”), a subsidiary of Celgene Corporation (which was acquired by Bristol Myers Squibb (“BMS”) in November 2019), pursuant to which Prothena granted to Celgene a right to elect in its sole discretion to exclusively license rights both in the U.S. (the “US Rights”) and on a global basis (the “Global Rights”), with respect to the Company’s programs to develop and commercialize antibodies targeting tau, TDP-43 and an undisclosed target (the “Collaboration Targets”). The Collaboration Agreement provided for Celgene making an upfront payment to the Company of $100.0 million, plus future potential license exercise payments and regulatory and commercial milestones for each program under the Collaboration Agreement, as well as royalties on net sales of any resulting marketed products. In connection with the Collaboration Agreement, the Company and Celgene entered into a Share Subscription Agreement on March 20, 2018, under which Celgene subscribed to 1,174,536 of the Company’s ordinary shares for a price of $42.57 per share, for a total of approximately $50.0 million. BMS US and Global Rights and Licenses On a program-by-program basis, beginning on the effective date of the Collaboration Agreement and ending on the date that the IND Option term expires for such program (which generally occurs sixty days after the date on which the Company delivers to BMS the first complete data package for an IND that was filed for a lead candidate from the relevant program), BMS may elect in its sole discretion to exercise its US Rights to receive an exclusive license to develop, manufacture and commercialize antibodies targeting the applicable Collaboration Target in the U.S. (the “US License”). If BMS exercises its US Rights for a collaboration program, it is obligated to pay the Company an exercise fee of approximately $80.0 million per program. Thereafter, following the first to occur of (a) completion by the Company, in its discretion and at its cost, of Phase 1 clinical trials for such program or (b) BMS’ election to assume responsibility to complete such Phase 1 clinical trials (at its cost), BMS would have the sole right to develop, manufacture and commercialize antibody products targeting the relevant Collaboration Target for such program (the “Collaboration Products”) in the U.S. On a program-by-program basis, following completion of a Phase 1 clinical trial for a collaboration program for which BMS has previously exercised its US Rights, BMS may elect in its sole discretion to exercise its Global Rights with respect to such collaboration program to receive a worldwide, exclusive license to develop, manufacture and commercialize antibodies targeting the applicable Collaboration Target (the “Global License”). If BMS exercises its Global Rights, BMS would be obligated to pay the Company an additional exercise fee of $55.0 million for such collaboration program. The Global Rights would then replace the US Rights for that collaboration program, and BMS would have decision making authority over developing, obtaining and maintaining regulatory approval for, manufacturing and commercializing the Collaboration Products worldwide. After BMS’ exercise of Global Rights for a collaboration program, the Company is eligible to receive up to $562.5 million in regulatory and commercial milestones per program. Following an exercise by BMS of either US Rights or Global Rights for such collaboration program, the Company will also be eligible to receive tiered royalties on net sales of Collaboration Products ranging from high single digit to high teen percentages, on a weighted average basis depending on the achievement of certain net sales thresholds. Such exercise fees, milestones and royalty payments are subject to certain reductions as specified in the Collaboration Agreement, the agreement for US Rights and the agreement for Global Rights. BMS will continue to pay royalties on a Collaboration Product-by-Collaboration Product and country-by-country basis, until the latest of (i) expiration of certain patents covering the Collaboration Product, (ii) expiration of all regulatory exclusivity for the Collaboration Product, and (iii) an agreed period of time after the first commercial sale of the Collaboration Product in the applicable country (the “Royalty Term”). Term and Termination The term of the Collaboration Agreement expired on May 24, 2024. The term of any US License or Global License would continue on a Licensed Product-by-Licensed Product and country-by-country basis until the expiration of all Royalty Terms under such agreement. Performance Obligations The Company assessed the Collaboration Agreement and concluded that it represented a contract with a customer within the scope of ASC 606. Per ASC 606, a performance obligation is defined as a promise to transfer a good or service or a series of distinct goods or services. At inception of the Collaboration Agreement, the Company is not obligated to transfer any US License or Global License to BMS unless BMS exercises its US Rights or Global Rights, respectively, and the Company is not obligated to perform development activities under the development plan during preclinical and Phase 1 clinical trials including the regulatory filing of the IND. The discovery, preclinical and clinical development activities performed by the Company are to be performed at the Company’s discretion and are not promised goods or services and therefore are not considered performance obligations under ASC 606, unless and until the Company agrees to perform the Phase 1 clinical trials (after the IND option exercise) that are determined to be performance obligations at the time the option is exercised. Per the terms of the Collaboration Agreement, the Company may conduct discovery activities to characterize, identify and generate antibodies to become collaboration candidates that target such Collaboration Target, and thereafter may pre-clinically develop collaboration candidates to identify lead candidates that target such Collaboration Target and file an IND with the U.S. Food and Drug Administration (the “FDA”) for a Phase 1 clinical trial for such lead candidates. In the event the Company agrees to be involved in a Phase 1 clinical trial, the Company will further evaluate whether any such promise represents a performance obligation at the time the option is exercised. If it is concluded that the Company has obligated itself to an additional performance obligation besides the license granted at IND option exercise, then the effects of the changes in the arrangement will be evaluated under the modification guidance of ASC 606. The Company is not obligated to perform manufacturing activities. Per the terms of the Collaboration Agreement, to the extent that the Company, at its discretion, conducts a program, the Company shall be responsible for the manufacture of collaboration candidates and collaboration products for use in such program, as well as the associated costs. Delivery of manufactured compound (clinical product supply) is not deemed a performance obligation under ASC 606 as the Company is not obligated to transfer supply of collaboration product to BMS unless BMS exercises its right to participate in the Phase 1 development. Compensation for the Company’s provision of inventory supply, to the extent requested by BMS would be paid to the Company by BMS at a reasonable stand-alone selling price for such supply. Given that (i) there is substantial uncertainty about the development of the programs, (ii) the pricing for the inventory is at its standalone selling price and (iii) the manufacturing services require the entity to transfer additional goods or services that are incremental to the goods and services provided prior to the resolution of the contingency, the Company’s supply of product is not a material right. Therefore, the inventory supply is not considered a performance obligation unless and until, requested by BMS. In addition to the grant of the Global License after BMS exercises the Global Rights for a program, BMS is entitled to receive certain ancillary development services from the Company, such as ongoing clinical trial support upon request by BMS, transition supply, if requested by BMS, and regulatory support for coordination of pharmacovigilance matters. The Company evaluated the potential obligations to transfer the US Licenses and Global Licenses and performance of the ancillary development services subsequent to exercise of the US Rights and Global Rights, if the options are exercised by BMS, under ASC 606-10-55-42 and 55-43 to determine whether the US Rights or the Global Rights provided BMS a “material right” and concluded that BMS’ options to exercise its US Rights and Global Rights represented “material rights” to BMS that it would not have received without entering into the Collaboration Agreement. At inception of the Collaboration Agreement, there were a total of six options, including US Rights and Global Rights to acquire a US License and a Global License, respectively, and rights to request certain development services (following exercise of the US Rights and Global Rights, respectively) for each of the three programs. None of which were remaining as of May 24, 2024. The deferred revenue balance as of June 30, 2025 of $5.1 million is related to the outstanding PRX019 Phase 1 clinical trial obligation (“PRX019 Phase 1 Clinical Trial Obligation”). US License Agreement for the Tau/BMS-986446 Collaboration Target BMS exercised its US Rights for the tau/BMS-986446 (formerly PRX005) Collaboration Target and on July 30, 2021, PBL entered into a U.S. License Agreement granting BMS an exclusive license to develop, manufacture and commercialize tau Collaboration Products in the United States targeting tau (the “Tau US License Agreement”). The Company received an associated option exercise fee of $80.0 million. The Tau US License Agreement included the following distinct performance obligations: (1) the delivery of the US License for tau/BMS-986446 Collaboration Target (“Tau US License Obligation”); and (2) the Company’s obligation to provide development activities under the development plan during any Phase 1 clinical trials (the “Tau US Development Services Obligation”). Revenue allocated to the Tau US License Obligation was recognized when the Company satisfied its obligation at a point in time, while the revenue allocated to the Tau US Development Services Obligation was recognized over time using an input-based model. All performance obligations have been delivered. Global License Agreement for the Tau/BMS-986446 Collaboration Target Subsequently, BMS exercised its Global Rights for the tau/BMS-986446 Collaboration Target and on July 5, 2023, PBL entered into a Global License Agreement granting BMS an exclusive license to develop, manufacture and commercialize tau Collaboration Products globally for any and all uses or purposes with respect to any human or animal disease, disorder or condition (the “Tau Global License Agreement”). The Tau Global License Agreement supersedes and replaces the Tau US License Agreement in its entirety. The Company received an associated option exercise fee of $55.0 million in August 2023 and it is eligible to receive regulatory and sales milestones up to $562.5 million upon achievement of certain events, including regulatory approval of a tau Collaboration Product, and on BMS achieving certain annual, worldwide net sales thresholds. The Company also is eligible to receive tiered royalties on net sales of tau Collaboration Products, ranging from high single digit to high teen percentages, on a weighted average basis depending on the achievement of certain net sales thresholds. The Company’s distinct performance obligation under the Tau Global License Agreement was limited to the delivery of the Global License for tau/BMS-986446 Collaboration Target (“Tau Global License Obligation”). Revenue allocated to the Tau Global License Obligation was recognized by the Company at the time that the license was delivered in July 2023. Global License Agreement for the undisclosed/PRX019 Collaboration Target On May 24, 2024, PBL entered into a Global License Agreement granting BMS an exclusive license to develop, manufacture and commercialize Collaboration Products targeting an undisclosed target (including PRX019) globally for any and all uses or purposes with respect to any human or animal disease, disorder or condition (the “PRX019 Global License Agreement”). The Company received an associated option exercise fee of $80.0 million in June 2024 and is eligible to receive further development and regulatory milestones of up to $242.5 million upon achievement of certain development and regulatory milestones, including regulatory approval, of a Collaboration Product, and up to $375.0 million upon BMS achieving certain annual, worldwide net sales thresholds. The Company also is eligible to receive tiered royalties on annual, worldwide net sales of Collaboration Products, ranging from high single digit to high teen percentages, on a weighted average basis depending on the achievement of certain net sales thresholds. Such milestones and royalty payments (i) could be reduced in the case where BMS is successful in developing a modified version of PRX019 that achieves certain specified improved metrics, and (ii) are subject to certain reductions as specified in the PRX019 Global License Agreement. The PRX019 Global License Agreement included the following distinct performance obligations: (1) the delivery of the Global License for the undisclosed Collaboration Target (“PRX019 Global License Obligation”); and (2) the Company’s obligation to run a Phase 1 clinical trial for PRX019. Pursuant to the terms of the PRX019 Global License Agreement, BMS may elect to assume responsibility for completing such Phase 1 clinical trial (at its cost). Revenue allocated to the PRX019 Global License Obligation was recognized when the Company satisfied its obligation at a point in time, while the revenue allocated to the PRX019 Phase 1 Clinical Trial Obligation is recognized over time using an input-based model. Transaction Price At inception of the Collaboration Agreement, the Company did not transfer any goods or services to BMS that were material. Accordingly, the Company concluded that the initial transaction price would be recognized as a contract liability and would be deferred until the Company transfers control of goods or services to BMS (which would be when BMS exercises the US Right or Global Right and receives control of the US License or Global License for at least one of the programs), or when the IND Option term expires if BMS had not yet exercised the US Right, or when the Phase 1 Option term expires if BMS had not yet exercised the Global Right, or at the termination of the Collaboration Agreement, whichever occurs first. At such point that the Company transfers control of goods or services to BMS, or when the option expires, the Company would recognize revenue as a continuation of the original contract. Under this approach, the Company would treat the consideration allocated to the material right as an addition to the consideration for the goods or services underlying the contract option. At inception of the Collaboration Agreement, the Company estimated the standalone selling price for each performance obligation (i.e., the US Rights and Global Rights by program). The estimate of standalone selling price for the US Rights and Global Rights by program was based on the adjusted market assessment approach using a discounted cash flow model. The key assumptions used in the discounted cash flow model included the market opportunity for commercialization of each program in the U.S. or globally depending on the license, the probability of successfully developing and commercializing a given program target, the estimated remaining development costs for the respective program, the estimated time to commercialization of the drug for that program, and a discount rate. The initial transaction price under the Collaboration Agreement, pursuant to ASC 606, was $110.2 million, including the $100.0 million upfront payment and $10.2 million premium on the ordinary shares purchased under the SSA. The Company allocated the initial transaction price across the US Rights and Global Rights for each program in a range of approximately $15-$25 million and $10-$18 million, respectively. The Company did not include the option fees in the initial transaction price because such fees are contingent on the options to the US Rights and the Global Rights being exercised. Upon the exercise of the US Rights and the Global Rights for a program, the Company would have the obligation to deliver the US License and Global License and provide certain ancillary development services if requested by BMS, subsequent to its exercise of the US Rights and Global Rights, respectively, for such program. The Company would include the option fees in the transaction price at the point in time a material right is exercised and the Company transfers control of the goods and services to BMS. In addition, the Company did not include in the initial transaction price certain clinical and regulatory milestone payments since they relate to licenses for which BMS had not yet exercised its option to obtain and these variable considerations are constrained due to the likelihood of a significant revenue reversal. Upon entering into the Tau Global License Agreement, the Company granted BMS a Global License for the tau/BMS-986446 Collaboration Target, which transferred control of such underlying Global License to BMS. Following execution of the Tau Global License Agreement, BMS paid the Company a $55.0 million option exercise fee. Under the continuation of the original contract method, the Company computed the relative sales price after the Company transferred control of the Global License for tau/BMS-986446. The Company used the original allocated consideration for the Global Right for tau/BMS-986446 of $17.9 million (computed at the inception of the contract) plus the $55.0 million option exercise fee to arrive at the total transaction price of approximately $72.9 million. Given that the Company’s distinct performance obligation under the Tau Global License Agreement was limited to the Tau Global License Obligation no further allocation was required. Upon entering into the PRX019 Global License Agreement, the Company granted BMS a Global License for the undisclosed/PRX019 Collaboration Target, which transferred control of such underlying Global License to BMS. Following execution of the PRX019 Global License Agreement, BMS paid the Company an $80.0 million option exercise fee. As the original contract contemplated a US and Global payment for $80.0 million and $55.0 million, respectively, and a new payment structure and only one license was agreed to, accordingly, the payment was accounted for under modification accounting. The Company concluded that the modification would be accounted for on a prospective basis as a termination of the existing contract and creation of a new contract. The Company computed the relative sales price for the identified remaining performance obligations consisting of the Global License for PRX019 and the PRX019 Phase 1 Clinical Trial Obligation. The transaction price consisted of the original allocated consideration for the US Right for PRX019 of $24.9 million, and original allocated consideration for the Global Right for PRX019 of $17.4 million (both computed at the inception of the Collaboration Agreement) plus the $80.0 million option exercise fee to arrive at the total transaction price of approximately $122.4 million. This total transaction price was allocated using the relative sales price method between the PRX019 Global License Obligation and the PRX019 Phase 1 Clinical Trial Obligation. The best estimate of selling price for the Global License for PRX019 was based on a discounted cash flow model. The key assumptions used in the discounted cash flow model used to determine the best estimate of selling price for the license included the market opportunity for commercialization of PRX019, the probability of successfully developing/commercializing PRX019, the remaining development costs for PRX019, and the estimated time to commercialization of PRX019 using a discount rate of 13%. Based on the relative selling price method, the amount that the Company allocated to the performance obligations was as follows: $106.3 million to the license to be recognized concurrent with the delivery of the license; and $16.1 million as development services for the Phase 1 clinical trial to be recognized based on input-based model over the service period. Significant Payment Terms The upfront payment of $100.0 million was received in April 2018, while all option fees and milestone payments are due within 30 days after the achievement of the relevant milestone by BMS or receipt by BMS of an invoice for such an amount from the Company. The Collaboration Agreement does not have a significant financing component since a substantial amount of consideration promised by BMS to the Company is variable and the amount of such variable consideration varies based upon the occurrence or non-occurrence of future events that are not within the control of either BMS or the Company. Variable considerations related to clinical and regulatory milestone payments and option fees are constrained due to the likelihood of a significant revenue reversal. Revenue and Expense Recognition For the three and six months ended June 30, 2025, collaboration revenue from BMS was $4.4 million and $7.2 million, respectively, and $132.0 million and $132.0 million for the three and six months ended June 30, 2024, respectively. Collaboration revenue for the three and six months ended June 30, 2025 was related to the Company’s partial performance of its PRX019 Phase 1 Clinical Trial Obligation. As of June 30, 2025, the aggregate amount of the transaction price allocated to the performance obligations that are unsatisfied was $5.1 million. The Company had nil and nil accounts receivable from BMS at June 30, 2025, and December 31, 2024, respectively. Deferred Revenue The deferred revenue balance at the beginning of the quarter ended June 30, 2025 was $9.5 million. During the quarter ended June 30, 2025, $4.4 million of deferred revenue was recognized as collaboration revenue related to the PRX019 Phase 1 Clinical Trial Obligation performed. As of June 30, 2025, the total deferred revenue balance of $5.1 million, classified as current deferred revenue, relates to outstanding performance obligations related to the PRX019 Phase 1 Clinical Trial Obligation. The deferred revenue balance will be recognized as revenue over the remaining service period. Milestone and Royalties Accounting Under the Tau Global License Agreement, the Company is eligible to receive milestone payments of up to $187.5 million upon the achievement of certain specified regulatory milestones and milestone payments of up $375.0 million upon the achievement of certain specified commercial sale milestones. Under the PRX019 Global License Agreement, the Company is eligible to receive milestone payments of up to $242.5 million upon the achievement of certain specified development and regulatory milestones and milestone payments of up $375.0 million upon the achievement of certain specified commercial sale milestones. Milestone payments are evaluated under ASC Topic 606. Factors considered in this determination included scientific and regulatory risk that must be overcome to achieve each milestone, the level of effort and investment required to achieve the milestone, and the monetary value attributed to the milestone. Accordingly, the Company estimates payments in the transaction price based on the most likely approach, which considers the single most likely amount in a range of possible amounts related to the achievement of these milestones. Additionally, milestone payments are included in the transaction price only when the Company can conclude it is probable that a significant revenue reversal will not occur in future periods. The Company excluded the milestone payments and royalties in the initial transaction price because such payments are considered to be variable considerations with constraint. Such milestone payments and royalties will be recognized as revenue at a point in time when the Company can conclude it is probable that a significant revenue reversal will not occur in future periods. BMS did not achieve any milestones under either the Tau Global License Agreement or the PRX019 Global License Agreement during the three and six months ended June 30, 2025 and 2024, respectively. Novo Nordisk Share Purchase Agreement On July 8, 2021, the Company together with its wholly owned subsidiary, PBL, entered into a definitive share purchase agreement with Novo Nordisk A/S and Novo Nordisk Region Europe A/S (each an unrelated party). Under the terms of such agreement, Novo Nordisk acquired PBL’s wholly-owned subsidiary, Neotope Neuroscience Limited (“NNL”) and gained full worldwide rights to the intellectual property and related rights to the Company’s ATTR amyloidosis business and pipeline. Upon consummation of the transaction, NNL ceased to be a related party of PBL. The aggregate purchase price consisted of an upfront payment of $60.0 million in cash, subject to customary purchase price adjustments. Should Novo Nordisk achieve certain stages of development or commercialization for products or product candidates containing coramitug (formerly PRX004) or a derivative thereof in ATTR amyloidosis, PBL is entitled to receive certain milestone payments based on specified development and commercial milestones. The development and commercialization milestone payments will be discounted if the milestone events are achieved with respect to other indications. Should Novo Nordisk achieve specified thresholds of worldwide, annual net sales of the milestone products, regardless of indication, PBL will also be entitled to receive specified one-time net sales milestone payments. All milestone payments attributable to an achieved milestone will be paid to PBL, subject to Novo Nordisk’s offset right for indemnity claims or unpaid amounts in respect of any purchase price adjustment. The upfront payment of $60.0 million was accounted for as revenue in 2021. In addition to the upfront payment, Novo Nordisk agreed to pay for certain out of pocket expenses under the Transition Services Agreement, which netted to $0.7 million after closing adjustments related to the sale of the ATTR amyloidosis business and pipeline. Contingent Consideration/Milestone Accounting In December 2022, the Company received a $40.0 million development milestone payment related to the continued advancement of coramitug in a Phase 2 clinical trial for the treatment of ATTR cardiomyopathy. This amount was accounted for as revenue from license and intellectual property in 2022. The Company is eligible to receive additional development and sales milestone payments from Novo Nordisk totaling up to $1.13 billion upon achievement of certain specified development and commercial sales milestones under the share purchase agreement. Novo Nordisk did not achieve any milestones under the share purchase agreement during the three and six months ended June 30, 2025 and 2024, respectively. The Company excluded the milestone payments in the initial transaction price because such payments are considered to be variable considerations with constraint. Such milestone payments will be recognized as revenue at a point in time when the Company can conclude it is probable that a significant revenue reversal will not occur in future periods. Revenue Recognition No revenue was recognized related to the transaction during the three and six months ended June 30, 2025 and 2024, respectively. The Company had no accounts receivable from Novo Nordisk as of June 30, 2025, and December 31, 2024, respectively.

In December 2013, the Company through its wholly owned subsidiary Prothena Biosciences Limited and Prothena Biosciences Inc entered into a License, Development, and Commercialization Agreement (the “License Agreement”) with F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. (together, “Roche”) to develop and commercialize certain antibodies that target α-synuclein, including prasinezumab, which are referred to collectively as “Licensed Products.” Upon the effectiveness of the License Agreement in January 2014, the Company granted to Roche an exclusive, worldwide license to develop, make, have made, use, sell, offer to sell, import and export the Licensed Products. The Company retained certain rights to conduct development of the Licensed Products and an option to co-promote prasinezumab in the U.S. During the term of the License Agreement, the Company and Roche will work exclusively with each other to research and develop antibody products targeting alpha-synuclein (or α-synuclein) potentially including incorporation of Roche’s proprietary Brain Shuttle™ technology to potentially increase delivery of therapeutic antibodies to the brain. The License Agreement provided for Roche making an upfront payment to the Company of $30.0 million, which was received in February 2014; making a clinical milestone payment of $15.0 million upon initiation of the Phase 1 clinical trial for prasinezumab, which was received in May 2014; making a clinical milestone payment of $30.0 million upon dosing of the first patient in the Phase 2 clinical trial for prasinezumab, which was achieved in June 2017; and making a clinical milestone payment of $60.0 million upon dosing of the first patient in the global Phase 2b PADOVA study for prasinezumab, which was achieved in May 2021.

Roche bore 100% of the cost of conducting the research collaboration under the License Agreement during the research term, which expired December 31, 2017. In May 2021, the Company exercised its rights under the terms of License Agreement to receive potential U.S. commercial sales milestone and royalties, in lieu of a U.S. profit and loss share for prasinezumab in Parkinson’s disease. Thus, in the U.S., through May 28, 2021, the parties shared all development costs, all of which were allocated 70% to Roche and 30% to the Company, for prasinezumab in the Parkinson’s disease indication. If the Company opts in to participate in co-development and co-funding for any other Licensed Products and/or indications, the parties will share all development and commercialization costs, as well as profits, all of which will be allocated 70% to Roche and 30% to the Company.

In addition, the Company has an option under the License Agreement to co-promote prasinezumab in the U.S. in the Parkinson’s disease indication. If the Company exercises such option, it may also elect to co-promote additional Licensed Products in the U.S. approved for Parkinson’s disease. Outside the U.S., Roche will have responsibility for developing and commercializing the Licensed Products. Roche bears all costs that are specifically related to obtaining or maintaining regulatory approval outside the U.S. and will pay the Company a variable royalty based on annual net sales of the Licensed Products outside the U.S.

The License Agreement continues on a country-by-country basis until the expiration of all payment obligations under the License Agreement. The License Agreement may also be terminated (i) by Roche at will after the first anniversary of the effective date of the License Agreement, either in its entirety or on a Licensed Product-by-Licensed Product basis, upon 90 days’ prior written notice to the Company prior to first commercial sale and 180 days’ prior written notice to Prothena after first commercial sale, (ii) by either party, either in its entirety or on a Licensed Product-by-Licensed Product or region-by-region basis, upon written notice in connection with a material breach uncured 90 days after initial written notice, and (iii) by either party, in its entirety, upon insolvency of the other party. The License Agreement may be terminated by either party on a patent-by-patent and country-by-country basis if the other party challenges a given patent in a given country. The Company’s rights to co-develop Licensed Products under the License Agreement will terminate if the Company commences certain studies for

The License Agreement cannot be assigned by either party without the prior written consent of the other party, except to an affiliate of such party or in the event of a merger or acquisition of such party, subject to certain conditions. The License Agreement also includes customary provisions regarding, among other things, confidentiality, intellectual property ownership, patent prosecution, enforcement and defense, representations and warranties, indemnification, insurance, and arbitration and dispute resolution.

Under the License Agreement, the Company is eligible to receive certain milestone payments upon the achievement of development, regulatory and various first commercial sales milestones. Milestone payments are evaluated under ASC Topic 606. Factors considered in this determination included scientific and regulatory risk that must be overcome to achieve each milestone, the level of effort and investment required to achieve the milestone, and the monetary value attributed to the milestone. Accordingly, the Company estimates payments in the transaction price based on the most likely approach, which considers the single most likely amount in a range of possible amounts related to the achievement of these milestones. Additionally, milestone payments are included in the transaction price only when the Company can conclude it is probable that a significant revenue reversal will not occur in future periods when the milestone is achieved.

The Company excludes the milestone payments and royalties in the initial transaction price calculation because such payments are considered to be variable considerations with constraint. Such milestone payments and royalties will be recognized as revenue once the Company can conclude it is probable that a significant revenue reversal will not occur in future periods.

The clinical and regulatory milestones under the License Agreement after the point at which the Company could opt out are considered to be variable considerations with constraint due to the fact that active participation in the development activities that generate the milestones is not required under the License Agreement, and the Company can opt out of these activities. There are no refunds or claw-back provisions and the milestones are uncertain of occurrence even after the Company has opted out. Based on this determination, these milestones will be recognized when the Company can conclude it is probable that a significant revenue reversal will not occur in future periods.

On March 20, 2018, the Company, through its wholly owned subsidiary Prothena Biosciences Limited (“PBL”), entered into a Master Collaboration Agreement (the “Collaboration Agreement”) with Celgene Switzerland LLC (“Celgene”), a subsidiary of Celgene Corporation (which was acquired by Bristol Myers Squibb (“BMS”) in November 2019), pursuant to which Prothena granted to Celgene a right to elect in its sole discretion to exclusively license rights both in the U.S. (the “US Rights”) and on a global basis (the “Global Rights”), with respect to the Company’s programs to develop and commercialize antibodies targeting tau, TDP-43 and an undisclosed target (the “Collaboration Targets”).

The Collaboration Agreement provided for Celgene making an upfront payment to the Company of $100.0 million, plus future potential license exercise payments and regulatory and commercial milestones for each program under the Collaboration Agreement, as well as royalties on net sales of any resulting marketed products. In connection with the Collaboration Agreement, the Company and Celgene entered into a Share Subscription Agreement on March 20, 2018, under which Celgene subscribed to 1,174,536 of the Company’s ordinary shares for a price of $42.57 per share, for a total of approximately $50.0 million.

On a program-by-program basis, beginning on the effective date of the Collaboration Agreement and ending on the date that the IND Option term expires for such program (which generally occurs sixty days after the date on which the Company delivers to BMS the first complete data package for an IND that was filed for a lead candidate from the relevant program), BMS may elect in its sole discretion to exercise its US Rights to receive an exclusive license to develop, manufacture and commercialize antibodies targeting the applicable Collaboration Target in the U.S. (the “US License”). If BMS exercises its US Rights for a collaboration program, it is obligated to pay the Company an exercise fee of approximately $80.0 million per program. Thereafter, following the first to occur of (a) completion by the Company, in its discretion and at its cost, of Phase 1 clinical trials for such program or (b) BMS’ election to assume responsibility to complete such Phase 1 clinical trials (at its cost), BMS would have the sole right to develop, manufacture and commercialize antibody products targeting the relevant Collaboration Target for such program (the “Collaboration Products”) in the U.S.

On a program-by-program basis, following completion of a Phase 1 clinical trial for a collaboration program for which BMS has previously exercised its US Rights, BMS may elect in its sole discretion to exercise its Global Rights with respect to such collaboration program to receive a worldwide, exclusive license to develop, manufacture and commercialize antibodies targeting the applicable Collaboration Target (the “Global License”). If BMS exercises its Global Rights, BMS would be obligated to pay the Company an additional exercise fee of $55.0 million for such collaboration program. The Global Rights would then replace the US Rights for that collaboration program, and BMS would have decision making authority over developing, obtaining and maintaining regulatory approval for, manufacturing and commercializing the Collaboration Products worldwide.

After BMS’ exercise of Global Rights for a collaboration program, the Company is eligible to receive up to $562.5 million in regulatory and commercial milestones per program. Following an exercise by BMS of either US Rights or Global Rights for such collaboration program, the Company will also be eligible to receive tiered royalties on net sales of Collaboration Products ranging from high single digit to high teen percentages, on a weighted average basis depending on the achievement of certain net sales thresholds. Such exercise fees, milestones and royalty payments are subject to certain reductions as specified in the Collaboration Agreement, the agreement for US Rights and the agreement for Global Rights.

BMS will continue to pay royalties on a Collaboration Product-by-Collaboration Product and country-by-country basis, until the latest of (i) expiration of certain patents covering the Collaboration Product, (ii) expiration of all regulatory exclusivity for the Collaboration Product, and (iii) an agreed period of time after the first commercial sale of the Collaboration Product in the applicable country (the “Royalty Term”).

The Company assessed the Collaboration Agreement and concluded that it represented a contract with a customer within the scope of ASC 606. Per ASC 606, a performance obligation is defined as a promise to transfer a good or service or a series of distinct goods or services. At inception of the Collaboration Agreement, the Company is not obligated to transfer any US License or Global License to BMS unless BMS exercises its US Rights or Global Rights, respectively, and the Company is not obligated to perform development activities under the development plan during preclinical and Phase 1 clinical trials including the regulatory filing of the IND.

The discovery, preclinical and clinical development activities performed by the Company are to be performed at the Company’s discretion and are not promised goods or services and therefore are not considered performance obligations under ASC 606, unless and until the Company agrees to perform the Phase 1 clinical trials (after the IND option exercise) that are determined to be performance obligations at the time the option is exercised. Per the terms of the Collaboration Agreement, the Company may conduct discovery activities to characterize, identify and generate antibodies to become collaboration candidates that target such Collaboration Target, and thereafter may pre-clinically develop collaboration candidates to identify lead candidates that target such Collaboration Target and file an IND with the U.S. Food and Drug Administration (the “FDA”) for a Phase 1 clinical trial for such lead candidates. In the event the Company agrees to be involved in a Phase 1 clinical trial, the Company will further evaluate whether any such promise represents a performance obligation at the time the option is exercised. If it is concluded that the Company has obligated itself to an additional performance obligation besides the license

The Company is not obligated to perform manufacturing activities. Per the terms of the Collaboration Agreement, to the extent that the Company, at its discretion, conducts a program, the Company shall be responsible for the manufacture of collaboration candidates and collaboration products for use in such program, as well as the associated costs. Delivery of manufactured compound (clinical product supply) is not deemed a performance obligation under ASC 606 as the Company is not obligated to transfer supply of collaboration product to BMS unless BMS exercises its right to participate in the Phase 1 development.

Compensation for the Company’s provision of inventory supply, to the extent requested by BMS would be paid to the Company by BMS at a reasonable stand-alone selling price for such supply. Given that (i) there is substantial uncertainty about the development of the programs, (ii) the pricing for the inventory is at its standalone selling price and (iii) the manufacturing services require the entity to transfer additional goods or services that are incremental to the goods and services provided prior to the resolution of the contingency, the Company’s supply of product is not a material right. Therefore, the inventory supply is not considered a performance obligation unless and until, requested by BMS.

The Company evaluated the potential obligations to transfer the US Licenses and Global Licenses and performance of the ancillary development services subsequent to exercise of the US Rights and Global Rights, if the options are exercised by BMS, under ASC 606-10-55-42 and 55-43 to determine whether the US Rights or the Global Rights provided BMS a “material right” and concluded that BMS’ options to exercise its US Rights and Global Rights represented “material rights” to BMS that it would not have received without entering into the Collaboration Agreement.

At inception of the Collaboration Agreement, there were a total of six options, including US Rights and Global Rights to acquire a US License and a Global License, respectively, and rights to request certain development services (following exercise of the US Rights and Global Rights, respectively) for each of the three programs. None of which were remaining as of May 24, 2024. The deferred revenue balance as of June 30, 2025 of $5.1 million is related to the outstanding PRX019 Phase 1 clinical trial obligation (“PRX019 Phase 1 Clinical Trial Obligation”).

BMS exercised its US Rights for the tau/BMS-986446 (formerly PRX005) Collaboration Target and on July 30, 2021, PBL entered into a U.S. License Agreement granting BMS an exclusive license to develop, manufacture and commercialize tau Collaboration Products in the United States targeting tau (the “Tau US License Agreement”). The Company received an associated option exercise fee of $80.0 million.

The Tau US License Agreement included the following distinct performance obligations: (1) the delivery of the US License for tau/BMS-986446 Collaboration Target (“Tau US License Obligation”); and (2) the Company’s obligation to provide development activities under the development plan during any Phase 1 clinical trials (the “Tau US Development Services Obligation”). Revenue allocated to the Tau US License Obligation was recognized when the Company satisfied its obligation at a point in time, while the revenue allocated to the Tau US Development Services Obligation was recognized over time using an input-based model. All performance obligations have been delivered.

Subsequently, BMS exercised its Global Rights for the tau/BMS-986446 Collaboration Target and on July 5, 2023, PBL entered into a Global License Agreement granting BMS an exclusive license to develop, manufacture and commercialize tau Collaboration Products globally for any and all uses or purposes with respect to any human or animal disease, disorder or condition (the “Tau Global License Agreement”). The Tau Global License Agreement supersedes and replaces the Tau US License Agreement in its entirety. The Company received an associated option exercise fee of $55.0 million in August 2023 and it is eligible to receive regulatory and sales milestones up to $562.5 million upon achievement of certain events, including regulatory approval of a tau Collaboration Product, and on BMS achieving certain annual, worldwide net sales thresholds. The Company also is eligible to receive tiered royalties on net sales of tau Collaboration Products, ranging from high single digit to high teen percentages, on a weighted average basis depending on the achievement of certain net sales thresholds.

On May 24, 2024, PBL entered into a Global License Agreement granting BMS an exclusive license to develop, manufacture and commercialize Collaboration Products targeting an undisclosed target (including PRX019) globally for any and all uses or purposes with respect to any human or animal disease, disorder or condition (the “PRX019 Global License Agreement”). The Company received an associated option exercise fee of $80.0 million in June 2024 and is eligible to receive further development and regulatory milestones of up to $242.5 million upon achievement of certain development and regulatory milestones, including regulatory approval, of a Collaboration Product, and up to $375.0 million upon BMS achieving certain annual, worldwide net sales thresholds. The Company also is eligible to receive tiered royalties on annual, worldwide net sales of Collaboration Products, ranging from high single digit to high teen percentages, on a weighted average basis depending on the achievement of certain net sales thresholds. Such milestones and royalty payments (i) could be reduced in the case where BMS is successful in developing a modified version of PRX019 that achieves certain specified improved metrics, and (ii) are subject to certain reductions as specified in the PRX019 Global License Agreement.

The PRX019 Global License Agreement included the following distinct performance obligations: (1) the delivery of the Global License for the undisclosed Collaboration Target (“PRX019 Global License Obligation”); and (2) the Company’s obligation to run a Phase 1 clinical trial for PRX019. Pursuant to the terms of the PRX019 Global License Agreement, BMS may elect to assume responsibility for completing such Phase 1 clinical trial (at its cost). Revenue allocated to the PRX019 Global License Obligation was recognized when the Company satisfied its obligation at a point in time, while the revenue allocated to the PRX019 Phase 1 Clinical Trial Obligation is recognized over time using an input-based model.

At inception of the Collaboration Agreement, the Company did not transfer any goods or services to BMS that were material. Accordingly, the Company concluded that the initial transaction price would be recognized as a contract liability and would be deferred until the Company transfers control of goods or services to BMS (which would be when BMS exercises the US Right or Global Right and receives control of the US License or Global License for at least one of the programs), or when the IND Option term expires if BMS had not yet exercised the US Right, or when the Phase 1 Option term expires if BMS had not yet exercised the Global Right, or at the termination of the Collaboration Agreement, whichever occurs first. At such point that the Company transfers control of goods or services to BMS, or when the option expires, the Company would recognize revenue as a continuation of the original contract. Under this approach, the Company would treat the consideration allocated to the material right as an addition to the consideration for the goods or services underlying the contract option.

At inception of the Collaboration Agreement, the Company estimated the standalone selling price for each performance obligation (i.e., the US Rights and Global Rights by program). The estimate of standalone selling price for the US Rights and Global Rights by program was based on the adjusted market assessment approach using a discounted cash flow model. The key assumptions used in the discounted cash flow model included the market opportunity for commercialization of each program in the U.S. or globally depending on the license, the probability of successfully developing and commercializing a given program target, the estimated remaining development costs for the respective program, the estimated time to commercialization of the drug for that program, and a discount rate.

The initial transaction price under the Collaboration Agreement, pursuant to ASC 606, was $110.2 million, including the $100.0 million upfront payment and $10.2 million premium on the ordinary shares purchased under the SSA. The Company allocated the initial transaction price across the US Rights and Global Rights for each program in a range of approximately $15-$25 million and $10-$18 million, respectively.

The Company did not include the option fees in the initial transaction price because such fees are contingent on the options to the US Rights and the Global Rights being exercised. Upon the exercise of the US Rights and the Global Rights for a program, the Company would have the obligation to deliver the US License and Global License and provide certain ancillary development services if requested by BMS, subsequent to its exercise of the US Rights and Global Rights, respectively, for such program. The Company would include the option fees in the transaction price at the point in time a material right is exercised and the Company transfers control of the goods and services to BMS. In addition, the Company did not include in the initial transaction price certain clinical and regulatory milestone payments since they relate to licenses for which BMS had not yet exercised its option to obtain and these variable considerations are constrained due to the likelihood of a significant revenue reversal.

Upon entering into the Tau Global License Agreement, the Company granted BMS a Global License for the tau/BMS-986446 Collaboration Target, which transferred control of such underlying Global License to BMS. Following execution of the Tau Global License Agreement, BMS paid the Company a $55.0 million option exercise fee. Under the continuation of the original contract method, the Company computed the relative sales price after the Company transferred control of the Global License for tau/BMS-986446. The Company used the original allocated consideration for the Global Right for tau/BMS-986446 of $17.9 million (computed at the inception of the contract) plus the $55.0 million option exercise fee to arrive at the total transaction price of approximately $72.9 million. Given that the Company’s distinct performance obligation under the Tau Global License Agreement was limited to the Tau Global License Obligation no further allocation was required.

Upon entering into the PRX019 Global License Agreement, the Company granted BMS a Global License for the undisclosed/PRX019 Collaboration Target, which transferred control of such underlying Global License to BMS. Following execution of the PRX019 Global License Agreement, BMS paid the Company an $80.0 million option exercise fee. As the original contract contemplated a US and Global payment for $80.0 million and $55.0 million, respectively, and a new payment structure and only one license was agreed to, accordingly, the payment was accounted for under modification accounting. The Company concluded that the modification would be accounted for on a prospective basis as a termination of the existing contract and creation of a new contract. The Company computed the relative sales price for the identified remaining performance obligations consisting of the Global License for PRX019 and the PRX019 Phase 1 Clinical Trial Obligation. The transaction price consisted of the original allocated consideration for the US Right for PRX019 of $24.9 million, and original allocated consideration for the Global Right for PRX019 of $17.4 million (both computed at the inception of the Collaboration Agreement) plus the $80.0 million option exercise fee to arrive at the total transaction price of approximately $122.4 million. This total transaction price was allocated using the relative sales price method between the PRX019 Global License Obligation and the PRX019 Phase 1 Clinical Trial Obligation.

The best estimate of selling price for the Global License for PRX019 was based on a discounted cash flow model. The key assumptions used in the discounted cash flow model used to determine the best estimate of selling price for the license included the market opportunity for commercialization of PRX019, the probability of successfully developing/commercializing PRX019, the remaining development costs for PRX019, and the estimated time to commercialization of PRX019 using a discount rate of 13%. Based on the relative selling price method, the amount that the Company allocated to the performance obligations was as follows: $106.3 million to the license to be recognized concurrent with the delivery of the license; and $16.1 million as development services for the Phase 1 clinical trial to be recognized based on input-based model over the service period.

The Collaboration Agreement does not have a significant financing component since a substantial amount of consideration promised by BMS to the Company is variable and the amount of such variable consideration varies based upon the occurrence or non-occurrence of future events that are not within the control of either BMS or the Company. Variable considerations related to clinical and regulatory milestone payments and option fees are constrained due to the likelihood of a significant revenue reversal.

For the three and six months ended June 30, 2025, collaboration revenue from BMS was $4.4 million and $7.2 million, respectively, and $132.0 million and $132.0 million for the three and six months ended June 30, 2024, respectively. Collaboration revenue for the three and six months ended June 30, 2025 was related to the Company’s partial performance of its PRX019 Phase 1 Clinical Trial Obligation.

The deferred revenue balance at the beginning of the quarter ended June 30, 2025 was $9.5 million. During the quarter ended June 30, 2025, $4.4 million of deferred revenue was recognized as collaboration revenue related to the PRX019 Phase 1 Clinical Trial Obligation performed. As of June 30, 2025, the total deferred revenue balance of $5.1 million, classified as

Under the Tau Global License Agreement, the Company is eligible to receive milestone payments of up to $187.5 million upon the achievement of certain specified regulatory milestones and milestone payments of up $375.0 million upon the achievement of certain specified commercial sale milestones. Under the PRX019 Global License Agreement, the Company is eligible to receive milestone payments of up to $242.5 million upon the achievement of certain specified development and regulatory milestones and milestone payments of up $375.0 million upon the achievement of certain specified commercial sale milestones. Milestone payments are evaluated under ASC Topic 606. Factors considered in this determination included scientific and regulatory risk that must be overcome to achieve each milestone, the level of effort and investment required to achieve the milestone, and the monetary value attributed to the milestone. Accordingly, the Company estimates payments in the transaction price based on the most likely approach, which considers the single most likely amount in a range of possible amounts related to the achievement of these milestones. Additionally, milestone payments are included in the transaction price only when the Company can conclude it is probable that a significant revenue reversal will not occur in future periods.

The Company excluded the milestone payments and royalties in the initial transaction price because such payments are considered to be variable considerations with constraint. Such milestone payments and royalties will be recognized as revenue at a point in time when the Company can conclude it is probable that a significant revenue reversal will not occur in future periods.

On July 8, 2021, the Company together with its wholly owned subsidiary, PBL, entered into a definitive share purchase agreement with Novo Nordisk A/S and Novo Nordisk Region Europe A/S (each an unrelated party). Under the terms of such agreement, Novo Nordisk acquired PBL’s wholly-owned subsidiary, Neotope Neuroscience Limited (“NNL”) and gained full worldwide rights to the intellectual property and related rights to the Company’s ATTR amyloidosis business and pipeline. Upon consummation of the transaction, NNL ceased to be a related party of PBL. The aggregate purchase price consisted of an upfront payment of $60.0 million in cash, subject to customary purchase price adjustments.

Should Novo Nordisk achieve certain stages of development or commercialization for products or product candidates containing coramitug (formerly PRX004) or a derivative thereof in ATTR amyloidosis, PBL is entitled to receive certain milestone payments based on specified development and commercial milestones. The development and commercialization milestone payments will be discounted if the milestone events are achieved with respect to other indications. Should Novo Nordisk achieve specified thresholds of worldwide, annual net sales of the milestone products, regardless of indication, PBL will also be entitled to receive specified one-time net sales milestone payments. All milestone payments attributable to an achieved milestone will be paid to PBL, subject to Novo Nordisk’s offset right for indemnity claims or unpaid amounts in respect of any purchase price adjustment.

The Company is eligible to receive additional development and sales milestone payments from Novo Nordisk totaling up to $1.13 billion upon achievement of certain specified development and commercial sales milestones under the share purchase agreement. Novo Nordisk did not achieve any milestones under the share purchase agreement during the three and six months ended June 30, 2025 and 2024, respectively.