Kiniksa Pharmaceuticals International, plc

Previous wording

ARCALYST is an interleukin-1α (“IL-1α”) and interleukin-1β (“IL-1β”) cytokine trap. In 2017, we licensed ARCALYST from Regeneron, which discovered and initially developed the drug. Our exclusive license to ARCALYST from Regeneron includes worldwide rights, excluding the Middle East and North Africa, for all applications other than those in oncology and local administration to the eye or ear. We received FDA approval of ARCALYST for thetreatment of recurrent pericarditis and reduction in risk of recurrence in adults and children 12 years and older in March 2021. Recurrent pericarditis is a painful inflammatory cardiovascular disease with an estimated United States prevalent population of approximately 40,000 patients seeking and receiving medical treatment. ARCALYST is also approved in the United States for the treatment of Cryopyrin-Associated Periodic Syndromes (“CAPS”), including Familial Cold Autoinflammatory Syndrome (“FCAS”) and Muckle-Wells Syndrome in adults and children 12 years and older, and the maintenance of remission in Deficiency of Interleukin-1 Receptor Antagonist (“DIRA”) in adults and children weighing 10 kg or more. ARCALYST is commercially available across the United States through a select network of specialty pharmacies. We are responsible for sales and distribution of ARCALYST in all approved indications in the United States, and evenly split profits on sales, as well as third party proceeds, with Regeneron. In 2022, we granted Hangzhou Zhongmei Huadong Pharmaceutical Co., Ltd. (“Huadong”) exclusive rights to develop and commercialize ARCALYST in the Huadong Territory (as defined below). In 2023, Regeneron initiated a technology transfer of the manufacturing process for ARCALYST drug substance, and we are working to qualify Samsung as our replacement CDMO.

Current wording

ARCALYST is an interleukin-1α (“IL-1α”) and interleukin-1β (“IL-1β”) cytokine trap. In 2017, we licensed ARCALYST from Regeneron, which discovered and initially developed the drug. Our exclusive license to ARCALYST from Regeneron includes worldwide rights, excluding the Middle East and North Africa, for all applications other than those in oncology and local administration to the eye or ear. We received FDA approval of ARCALYST for thetreatment of recurrent pericarditis and reduction in risk of recurrence in adults and children 12 years and older in March 2021. Recurrent pericarditis is a painful inflammatory cardiovascular disease with an estimated United States prevalent population of approximately 40,000 patients seeking and receiving medical treatment. ARCALYST is also approved in the United States for the treatment of Cryopyrin-Associated Periodic Syndromes (“CAPS”), including Familial Cold Autoinflammatory Syndrome and Muckle-Wells Syndrome in adults and children 12 years and older, and the maintenance of remission in Deficiency of Interleukin-1 Receptor Antagonist (“DIRA”) in adults and children weighing 10 kg or more. ARCALYST is commercially available across the United States through a select network of specialty pharmacies. We are responsible for sales and distribution of ARCALYST in all approved indications in the United States, and evenly split profits on sales, as well as third party proceeds, with Regeneron. In 2022, we granted Hangzhou Zhongmei Huadong Pharmaceutical Co., Ltd. (“Huadong”) exclusive rights to develop and commercialize ARCALYST in the Huadong Territory (as defined below). In 2023, Regeneron initiated a technology transfer of the manufacturing process for ARCALYST drug substance, and we are working to qualify Samsung as our replacement CDMO. In December 2024, we initiated a collaborative study agreement with The Mayo Clinic (together with Johns Hopkins University) to investigate the effects of ARCALYST in the treatment of cardiac sarcoidosis.

Previous wording

KPL-387 is an investigational, fully human immunoglobulin G2 monoclonal antibody that binds human interleukin-1 receptor 1 (“IL-1R1”), inhibiting IL-1α- and IL-1β-mediated signaling. KPL-387 is an independently developed asset that we believe has the potential to further advance recurrent pericarditis treatment options for patients by providing the added convenience of monthly subcutaneous dosing with a liquid formulation. In June 2024, we initiated a Phase 1 clinical trial of KPL-387 in normal healthy volunteers. In July 2025, we announced that the Phase 2 dose-focusing portion of the pivotal Phase 2/3 clinical trial of KPL-387 in recurrent pericarditis had begun recruiting. We expect data from the Phase 2 portion of the trial in the second half of 2026.

Current wording

KPL-387 is an investigational, fully human immunoglobulin G2 monoclonal antibody that binds human interleukin-1 receptor 1 (“IL-1R1”), inhibiting IL-1α- and IL-1β-mediated signaling. KPL-387 is an independently developed asset that we believe has the potential to help grow the market and to further advance recurrent pericarditis treatment options for patients by potentially enabling dosing with a single monthly subcutaneous self-injection in a liquid formulation. In June 2024, we initiated a Phase 1 clinical trial of KPL-387 in normal healthy volunteers. In July 2025, we announced that the Phase 2 dose-focusing portion of the Phase 2/3 clinical trial of KPL-387 in recurrent pericarditis had begun recruiting. We expect data from the Phase 2 portion of the trial in the second half of 2026. In September 2025, we announced plans to conduct a supplemental Phase 2 transition to KPL-387 monotherapy dosing and administration study to evaluate the efficacy and safety of the dosing regimens used to transition patients from standard therapies to KPL-387 monotherapy. In October 2025, the FDA granted Orphan Drug Designation to KPL-387 for the treatment of pericarditis.

Previous wording

KPL-1161 is an independently developed, pre-clinical, Fc-modified immunoglobulin G2 monoclonal antibody that binds IL-1R1, inhibiting IL-1α- and IL-1β-mediated signaling. KPL-1161 is a modified version of KPL-387 designed to have an increased drug half-life that we believe could support quarterly subcutaneous dosing.

Current wording

KPL-1161 is an independently developed, pre-clinical, Fc-modified immunoglobulin G2 monoclonal antibody that binds IL-1R1, inhibiting IL-1α- and IL-1β-mediated signaling. KPL-1161 is a modified version of KPL-387 designed to have an increased drug half-life that we believe could support quarterly subcutaneous dosing. We are currently conducting IND-enabling activities with respect to this asset.

Previous wording

Abiprubart is an investigational monoclonal antibody inhibitor of CD40-CD154 costimulatory interaction, which we believe to be an attractive approach to address multiple autoimmune disease pathologies. We hold an exclusive worldwide license to abiprubart from Beth Israel Deaconess Medical Center, Inc. (“BIDMC”). We previously announced a Phase 2b clinical trial of abiprubart in Sjögren’s Disease. In February 2025, we announced our plans to discontinue development of abiprubart in the indication and explore strategic alternatives for the asset.

Current wording

Abiprubart is an investigational monoclonal antibody inhibitor of CD40-CD154 costimulatory interaction, which we believe to be an attractive approach to address multiple autoimmune disease pathologies. We hold an exclusive worldwide license to abiprubart from Beth Israel Deaconess Medical Center, Inc. (“BIDMC”). We previously announced a Phase 2b clinical trial of abiprubart in Sjögren’s Disease. In February 2025, we announced our plans to discontinue development of abiprubart in the indication and to explore strategic alternatives for the asset.

Previous wording

February 2025, we announced our termination of our license agreement from MedImmune for convenience, effective in May 2025. In April 2025, we entered into a mutual termination agreement with Huadong with respect to the mavrilimumab Huadong Collaboration Agreement (as defined below), pursuant to which we agreed to terminate the agreement and release all claims related thereto.

Current wording

Mavrilimumab is an investigational monoclonal antibody inhibitor targeting granulocyte-macrophage colony stimulating factor receptor alpha (“GM-CSFRα”). In 2017, we licensed exclusive worldwide rights in all indications to mavrilimumab from MedImmune, Limited, which has since been acquired by AstraZeneca PLC (“MedImmune”). In February 2025, we announced our termination of our license agreement from MedImmune for convenience, effective in May 2025. In April 2025, we entered into a mutual termination agreement with Huadong with respect to the mavrilimumab Huadong Collaboration Agreement (as defined below), pursuant to which we agreed to terminate the agreement and to release all claims related thereto.

Previous wording

Our ability to generate product revenue sufficient to sustain our organization will depend heavily on a number of factors, including the continued commercialization of ARCALYST, the development and eventual commercialization of one or more of our current or future product candidates, if approved, and the management of our costs consistent with our current operating plan. For the six months ended June 30, 2025, our net income was $26.4 million. As of June 30, 2025, we had an accumulated deficit of $494.8 million.

Current wording

Our ability to generate product revenue sufficient to sustain our organization will depend heavily on a number of factors, including the continued commercialization of ARCALYST, the development and eventual commercialization of one or more of our current or future product candidates, if approved, and the management of our costs consistent with our current operating plan. For the nine months ended September 30, 2025, our net income was $44.8 million. As of September 30, 2025, we had an accumulated deficit of $476.3 million.

Previous wording

As of June 30, 2025, we had cash, cash equivalents and short-term investments of $307.8 million. We believe that our existing cash, cash equivalents and short-term investments will enable us to fund our operating expenses and capital expenditure requirements for at least the next 12 months from the date of issuance of theunaudited consolidated financial statements included in this Quarterly Report. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect. See “—Liquidity and Capital Resources.”

Current wording

As of September 30, 2025, we had cash, cash equivalents and short-term investments of $352.1 million. We believe that our existing cash, cash equivalents and short-term investments will enable us to fund our operating expenses and capital expenditure requirements for at least the next 12 months from the date of issuance of theunaudited consolidated financial statements included in this Quarterly Report. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect. See “—Liquidity and Capital Resources.”

Previous wording

Our net revenues represent total revenues adjusted for discounts and allowances, including estimated cash discounts, chargebacks, rebates, returns, copay assistance, and specialty pharmacy and distributor fees. These adjustments represent variable consideration under ASC 606 and are estimated using the expected value method and are recorded when revenue is recognized on the sale of the product. These adjustments are established by management as its best estimate based on available information and will be adjusted to reflect known changes in the factors that impact such allowances. Adjustments for variable consideration are determined based on the contractual terms with customers, historical trends, communications with customers and the levels of inventory remaining in the distribution channel, as well as expectations about the market for the product and anticipated introduction of competitive products.

Current wording

best estimate based on available information and will be adjusted to reflect known changes in the factors that impact such allowances. Adjustments for variable consideration are determined based on the contractual terms with customers, historical trends, communications with customers and the levels of inventory remaining in the distribution channel, as well as expectations about the market for the product and anticipated introduction of competitive products.

Previous wording

In February 2022, we entered into two collaboration and license agreements (the “Huadong Collaboration Agreements”), with Huadong, pursuant to which we granted Huadong exclusive rights to develop and commercialize ARCALYST and mavrilimumab, in the Asia Pacific region excluding Japan (the “Huadong Territory”). In April 2025, we entered into a mutual termination agreement with Huadong pursuant to which we agreed to terminate the mavrilimumab Huadong Collaboration Agreement and release all claims related thereto.

Current wording

In February 2022, we entered into two collaboration and license agreements (the “Huadong Collaboration Agreements”), with Huadong, pursuant to which we granted Huadong exclusive rights to develop and commercialize ARCALYST and mavrilimumab, in the Asia Pacific region excluding Japan (the “Huadong Territory”). In April 2025, we entered into a mutual termination agreement with Huadong pursuant to which we agreed to terminate the mavrilimumab Huadong Collaboration Agreement and release all claims related thereto. The ARCALYST Huadong Collaboration Agreement remains in effect.

Previous wording

Under the Genentech License Agreement, we received an upfront payment of $80.0 million for the license. Additionally, in 2023, we received a total of $35.0 million in additional payments from Genentech related to delivery of certain drug material to Genentech and Genentech’s achievement of a development milestone. In the fourth quarter of 2023, following the achievement of a development milestone related to a second indication under the Genentech License Agreement, Genentech became obligated to make an additional cash payment of $10.0 million, which was received in the first quarter of 2024. In the second quarter of 2024, we received $5.0 million following the achievement of a development milestone related to a third indication under the Genentech License Agreement. We will be eligible to receive up to a total of approximately $600.0 million in contingent payments, including specified development, regulatory and sales-based milestones, of which approximately $570.0 million remains as of June 30, 2025. We will also be eligible to receive tiered percentage royalties on a Genentech Licensed Product-by-Genentech Licensed Product basis ranging from low-double digits to mid-teens on annual net sales of each Genentech Licensed Product, subject to certain customary reductions, with an aggregate minimum floor, before fulfilling our upstream financial obligations. Royalties will be payable on a Genentech Licensed Product-by-Genentech Licensed Product and country-by-country basis until the latest to occur of the expiration of certain patents that cover a Genentech Licensed Product, the expiration of regulatory exclusivity for such Genentech Licensed Product, or the tenth anniversary of first commercial sale of such Genentech Licensed Product in such country. In 2024, we completed our remaining obligations under the Genentech License Agreement and we have recognized as revenue all of the considerations received.

Current wording

Under the Genentech License Agreement, we received an upfront payment of $80.0 million for the license. Additionally, in 2023, we received a total of $35.0 million in additional payments from Genentech related to delivery of certain drug material to Genentech and Genentech’s achievement of a development milestone. In the fourth quarter of 2023, following the achievement of a development milestone related to a second indication under the Genentech License Agreement, Genentech became obligated to make an additional cash payment of $10.0 million, which was received in the first quarter of 2024. In the second quarter of 2024, we received $5.0 million following the achievement of a development milestone related to a third indication under the Genentech License Agreement. We will be eligible to receive up to a total of approximately $600.0 million in contingent payments, including specified development, regulatory and sales-based milestones, of which approximately $570.0 million remains as of September 30, 2025. We will also be eligible to receive tiered percentage royalties on a Genentech Licensed Product-by-Genentech Licensed Product basis ranging from low-double digits to mid-teens on annual net sales of each Genentech Licensed Product, subject to certain customary reductions, with an aggregate minimum floor, before fulfilling our upstream financial obligations. Royalties will be payable on a Genentech Licensed Product-by-Genentech Licensed Product and country-by-country basis until the latest to occur of the expiration of certain patents that cover a Genentech Licensed Product, the expiration of regulatory exclusivity for such Genentech Licensed Product, or the tenth anniversary of first commercial

Previous wording

Prior to the Redomiciliation, our principal holding company was incorporated and principally subject to taxation in Bermuda. Following the Redomiciliation, our principal holding company is incorporated and principally subject to taxation in the UK. Under the laws of Bermuda, there is no corporate income tax levied on an exempted company’s income, resulting in an effective zero percent tax rate. As a result, we have not recorded any income tax benefits from our losses incurred in Bermuda during the reporting periods in which we were incorporated there, and no net operating loss carryforwards are currently available to us for those losses. Following the Redomiciliation, our income is subject to the enacted UK statutory corporate tax rate and net operating losses incurred have an indefinite carryforward. Our wholly owned United States subsidiaries, Kiniksa Pharmaceuticals, Inc. (“Kiniksa US”), and Primatope Therapeutics, Inc. are subject to federal and state income taxes in the United States. Our wholly owned subsidiary Kiniksa Pharmaceuticals (UK), Ltd. (“Kiniksa UK”), its Swiss branch office, and Kiniksa UK’s wholly owned subsidiaries, Kiniksa Pharmaceuticals (Germany) GmbH, Kiniksa Pharmaceuticals (France) SARL, and Kiniksa Pharmaceuticals, GmbH (“Kiniksa Switzerland”) are subject to taxation in their respective countries.

Current wording

company’s income, resulting in an effective zero percent tax rate. As a result, we have not recorded any income tax benefits from our losses incurred in Bermuda during the reporting periods in which we were incorporated there, and no net operating loss carryforwards are currently available to us for those losses. Following the Redomiciliation, our income is subject to the enacted UK statutory corporate tax rate and net operating losses incurred have an indefinite carryforward. Our wholly owned United States subsidiaries, Kiniksa Pharmaceuticals, Inc. (“Kiniksa US”), and Primatope Therapeutics, Inc. are subject to federal and state income taxes in the United States. Our wholly owned subsidiary Kiniksa Pharmaceuticals (UK), Ltd. (“Kiniksa UK”), its Swiss branch office, and Kiniksa UK’s wholly owned subsidiaries, Kiniksa Pharmaceuticals (Germany) GmbH, Kiniksa Pharmaceuticals (France) SARL, and Kiniksa Pharmaceuticals, GmbH (“Kiniksa Switzerland”) are subject to taxation in their respective countries.

Previous wording

On July 4, 2025, new U.S tax legislation was signed into law (known as the "One Big Beautiful Bill Act" or "OBBBA") which makes permanent many of the tax provisions enacted in 2017 as part of the Tax Cuts and Jobs Act that were set to expire at the end of 2025. In addition, the OBBBA makes changes to certain U.S. corporate tax provisions, but many are generally not effective until 2026. We are currently evaluating the impact of the new legislation on our operations.

Current wording

On July 4, 2025, new U.S tax legislation was signed into law (known as the "One Big Beautiful Bill Act" or "OBBBA") which makes permanent many of the tax provisions enacted in 2017 as part of the Tax Cuts and Jobs Act that were set to expire at the end of 2025. In addition, the OBBBA makes changes to certain U.S. corporate tax provisions, but many are generally not effective until 2026. While we continue to assess the impact of the tax provisions of the OBBBA on our consolidated financial statements, we currently believe that the tax provisions of the legislation are not expected to have a material impact on our operations.

Previous wording

We recognized net revenue from the sale of ARCALYST of $156.8 million for the three months ended June 30, 2025, compared to $103.4 million for the three months ended June 30, 2024, an increase of $53.4 million. The increase in product revenue was primarily driven by an increase in patient enrollment.

Current wording

We recognized net revenue from the sale of ARCALYST of $180.9 million for the three months ended September 30, 2025, compared to $112.2 million for the three months ended September 30, 2024, an increase of $68.6 million. The increase in product revenue was driven primarily by an increase in patient enrollment.

Previous wording

We recognized cost of goods sold of $18.6 million for the three months ended June 30, 2025, compared to $12.3 million for the three months ended June 30, 2024, an increase of $6.3 million. The increase in cost of goods sold relates primarily to the increase in sales of ARCALYST and unfavorable production variances. Cost of goods sold related to the technology transfer of the manufacturing process were $1.7 million for the three months ended June 30, 2025, compared to $2.8 million for the three months ended June 30, 2024, a decrease of $1.1 million.

Current wording

We recognized cost of goods sold of $20.3 million for the three months ended September 30, 2025, compared to $20.1 million for the three months ended September 30, 2024, an increase of $0.1 million. The increase in cost of goods sold relates primarily to the increase in sales of ARCALYST offset by a decrease in technology transfer costs and favorable production variances. Cost of goods sold related to the technology transfer of the manufacturing process of ARCALYST drug substance were $4.4 million for the three months ended September 30, 2025, compared to $7.5 million for the three months ended September 30, 2024, a decrease of $3.1 million.

Previous wording

Collaboration expenses were $52.4 million for the three months ended June 30, 2025, compared to $30.0 million for the three months ended June 30, 2024, an increase of $22.4 million. Collaboration expenses increased due to increased revenue from sales of ARCALYST.

Current wording

Collaboration expenses were $63.3 million for the three months ended September 30, 2025, compared to $29.3 million for the three months ended September 30, 2024, an increase of $34.0 million. Collaboration expenses increased due to increased revenue from sales of ARCALYST.

Previous wording

Direct costs for our KPL-387 program were $8.5 million during the three months ended June 30, 2025, compared to $1.6 million during the three months ended June 30, 2024. The increase in expenses incurred primarily related to our Phase 1 clinical trial in normal healthy volunteers and the start-up of our Phase 2/3 clinical trial of KPL-387 in recurrent pericarditis during the three months ended June 30, 2025, as compared to the manufacturing of clinical supply during the three months ended June 30, 2024.

Current wording

Direct costs for our KPL-387 program were $11.4 million during the three months ended September 30, 2025, compared to $6.8 million during the three months ended September 30, 2024. The increase in expenses incurred primarily related to the start-up of our Phase 2/3 clinical trial in recurrent pericarditis during the three months ended September 30, 2025, as compared to the performance of our Phase 1 clinical trial in healthy volunteers during the three months ended September 30, 2024.

Previous wording

Direct costs for our KPL-1161 program were $0.4 million for the three months ended June 30, 2025, compared to $0.1 million during the three months ended June 30, 2024. For the three months ended June 30, 2025 and 2024, expenses incurred primarily related to pre-clinical development.

Current wording

Direct costs for our KPL-1161 program were $1.8 million for the three months ended September 30, 2025, compared to $0.3 million during the three months ended September 30, 2024. For the three months ended September 30, 2025 and 2024, expenses incurred primarily related to pre-clinical development.

Previous wording

The direct costs for our abiprubart program were $0.6 million during the three months ended June 30, 2025, compared to $12.4 million during the three months ended June 30, 2024, a decrease of $11.7 million. The decrease in expenses incurred primarily related to the close-out of our Phase 2b clinical trial in Sjögren’s Disease during the three months ended June 30, 2025, as compared to the manufacturing of clinical material, continuation of cohort four of our Phase 2 clinical trial in rheumatoid arthritis (“RA”) and start-up costs of our Phase 2b clinical trial in Sjögren’s Disease during the three months ended June 30, 2024.

Current wording

The direct costs for our abiprubart program were $0.7 million during the three months ended September 30, 2025, compared to $8.5 million during the three months ended September 30, 2024, a decrease of $7.8 million. The decrease in expenses incurred primarily related to the close-out of our Phase 2b clinical trial in Sjögren’s Disease during the three months ended September 30, 2025, as compared to the manufacturing of clinical material, continuation of cohort four of our Phase 2 clinical trial in rheumatoid arthritis (“RA”) and start-up costs of our Phase 2b clinical trial in Sjögren’s Disease during the three months ended September 30, 2024.

Previous wording

Unallocated research and development expenses were $9.1 million and $8.9 million for the three months ended June 30, 2025 and June 30, 2024, respectively. Personnel-related costs for the three months ended June 30, 2025 and 2024 included share-based compensation of $1.7 million and $1.5 million, respectively.

Current wording

Unallocated research and development expenses were $10.0 million and $10.1 million for the three months ended September 30, 2025 and September 30, 2024, respectively. Personnel-related costs for the three months ended September 30, 2025 and 2024 included share-based compensation of $1.7 million and $1.6 million, respectively.

Previous wording

Selling, general and administrative expenses were $90.4 million for the six months ended June 30, 2025, compared to $81.1 million for the six months ended June 30, 2024. The increase of $9.3 million was primarily due to an increase of $6.8 million in personnel-related costs largely attributable to an increase in headcount and an increase in

Current wording

Selling, general and administrative expenses were $49.1 million for the three months ended September 30, 2025, compared to $46.4 million for the three months ended September 30, 2024. The increase of $2.7 million was primarily due to an increase of $7.9 million in personnel-related costs largely attributable to an increase in headcount offset by a decrease in sales and marketing expenses of $4.0 million largely attributable to the timing of free goods designation. Personnel-related costs for the three months ended September 30, 2025 and 2024 included share-based compensation of $7.9 million and $5.8 million, respectively.

Previous wording

(“FDII”) deduction, benefits related to share-based compensation and United States federal and state research and development credits (“R&D Credits”). For the three months ended June 30, 2024, we recorded an income tax provision of $6.2 million relating primarily to income earned in the UK, Switzerland and the United States, net of the FDII deduction and R&D Credits.

Current wording

For the three months ended September 30, 2025, we recorded an income tax provision of $8.7 million relating primarily to income earned in Switzerland, the United States, and the UK, net of benefits related to share-based compensation, United States federal and state research and development credits (“R&D Credits”), and the Foreign Derived Intangible Income (“FDII”) deduction. For the three months ended September 30, 2024, we recorded an income tax provision of $5.5 million relating primarily to income earned in the UK, Switzerland and the United States, net of the FDII deduction and R&D Credits.

Previous wording

The following table summarizes our results of operations for the six months ended June 30, 2025 and 2024:

Current wording

The following table summarizes our results of operations for the nine months ended September 30, 2025 and 2024:

Previous wording

We recognized net revenue from the sale of ARCALYST of $294.6 million for the six months ended June 30, 2025, compared to $182.3 million for the six months ended June 30, 2024, an increase of $112.3 million. The increase in product revenue was primarily driven by an increase in patient enrollment.

Current wording

We recognized net revenue from the sale of ARCALYST of $475.4 million for the nine months ended September 30, 2025, compared to $294.5 million for the nine months ended September 30, 2024, an increase of $180.9 million. The increase in product revenue was driven primarily by an increase in patient enrollment.

Previous wording

We reported no license and collaboration revenue for the six months ended June 30, 2025. We reported $6.2 million of license and collaboration revenue for the six months ended June 30, 2024, primarily driven by the achievement of a $5.0 million development milestone related to a third indication under the Genentech License Agreement and $0.7 million of products sold under the ARCALYST Huadong Collaboration Agreements

Current wording

We reported no license and collaboration revenue for the nine months ended September 30, 2025. We reported $6.2 million of license and collaboration revenue for the nine months ended September 30, 2024, driven primarily by the achievement of a $5.0 million development milestone related to a third indication under the Genentech License Agreement and $0.7 million of products sold under the ARCALYST Huadong Collaboration Agreements

Previous wording

We recognized cost of goods sold of $36.5 million for the six months ended June 30, 2025, compared to $22.9 million for the six months ended June 30, 2024, an increase of $13.6 million. The increase in cost of goods sold relates primarily to the increase in sales of ARCALYST and unfavorable production variances. Cost of goods sold related to the technology transfer of the manufacturing process were $3.9 million for the three months ended June 30, 2025, compared to $4.9 million for the three months ended June 30, 2024, a decrease of $1.0 million.

Current wording

We recognized cost of goods sold of $56.7 million for the nine months ended September 30, 2025, compared to $43.0 million for the nine months ended September 30, 2024, an increase of $13.7 million. The increase in cost of goods sold relates primarily to the increase in sales of ARCALYST offset by a decrease in technology transfer costs. Cost of goods sold related to the technology transfer of the manufacturing process of ARCALYST drug substance were $8.3

Previous wording

Collaboration expenses were $96.2 million for the six months ended June 30, 2025, compared to $50.8 million for the six months ended June 30, 2024, an increase of $45.4 million. Collaboration expenses increased due to increased revenue from sales of ARCALYST.

Current wording

Collaboration expenses were $159.5 million for the nine months ended September 30, 2025, compared to $80.1 million for the nine months ended September 30, 2024, an increase of $79.4 million. Collaboration expenses increased due to increased revenue from sales of ARCALYST.

Previous wording

Direct costs for our KPL-387 program were $13.7 million during the six months ended June 30, 2025, compared to $2.7 million during the six months ended June 30, 2024. The increase in expenses incurred primarily related to our Phase 1 clinical trial in normal healthy volunteers and the start-up of our Phase 2/3 clinical trial of KPL-387 in recurrent pericarditis during the six months ended June 30, 2025, as compared to the manufacturing of clinical supply and our Phase 1 study in normal healthy volunteers during the six months ended June 30, 2024.

Current wording

Direct costs for our KPL-387 program were $25.0 million during the nine months ended September 30, 2025, compared to $9.5 million during the nine months ended September 30, 2024. The increase in expenses incurred primarily related to the start-up of our Phase 2/3 clinical trial in recurrent pericarditis during the nine months ended September 30, 2025, as compared to the performance of our Phase 1 clinical trial in healthy volunteers during the nine months ended September 30, 2024.

Previous wording

Direct costs for our KPL-1161 program were $0.5 million for the six months ended June 30, 2025, compared to $0.1 million during the six months ended June 30, 2024. For the six months ended June 30, 2025 and 2024, expenses incurred primarily related to pre-clinical development.

Current wording

Direct costs for our KPL-1161 program were $2.3 million for the nine months ended September 30, 2025, compared to $0.4 million during the nine months ended September 30, 2024. For the nine months ended September 30, 2025 and 2024, expenses incurred primarily related to pre-clinical development.

Previous wording

The direct costs for our abiprubart program were $5.0 million during the six months ended June 30, 2025, compared to $27.5 million during the six months ended June 30, 2024, a decrease of $22.5 million. The decrease in expenses incurred primarily related to the close-out of our Phase 2b clinical trial in Sjögren’s Disease during the six months ended June 30, 2025, as compared to the manufacturing of clinical material, continuation of cohort four of our Phase 2 clinical trial in RA and start-up costs of our Phase 2b clinical trial in Sjögren’s Disease during the six months ended June 30, 2024.

Current wording

The direct costs for our abiprubart program were $5.7 million during the nine months ended September 30, 2025, compared to $35.9 million during the nine months ended September 30, 2024, a decrease of $30.2 million. The decrease in expenses incurred primarily related to the close-out of our Phase 2b clinical trial in Sjögren’s Disease during the nine months ended September 30, 2025, as compared to the manufacturing of clinical material, continuation of cohort four of our Phase 2 clinical trial in RA and start-up costs of our Phase 2b clinical trial in Sjögren’s Disease during the nine months ended September 30, 2024.

Previous wording

Unallocated research and development expenses were $18.3 million for thesix months ended June 30, 2025, compared to $18.0 million for the six months ended June 30, 2024. Personnel-related costs for the six months ended June 30, 2025 and 2024 included share-based compensation of $3.2 million and $3.0 million, respectively.

Current wording

Unallocated research and development expenses were $28.3 million for thenine months ended September 30, 2025, compared to $28.0 million for the nine months ended September 30, 2024. Personnel-related costs for the nine months ended September 30, 2025 and 2024 included share-based compensation of $4.9 million and $4.6 million, respectively.

Previous wording

Selling, general and administrative expenses were $46.9 million for the three months ended June 30, 2025, compared to $42.4 million for the three months ended June 30, 2024. The increase of $4.5 million was primarily due to an increase of $4.4 million in personnel-related costs largely attributable to an increase in headcount. Personnel-related costs for the three months ended June 30, 2025 and 2024 included share-based compensation of $6.6 million and $5.5 million, respectively.

Current wording

Selling, general and administrative expenses were $139.5 million for the nine months ended September 30, 2025, compared to $127.5 million for the nine months ended September 30, 2024. The increase of $12.0 million was primarily due to an increase of $14.8 million in personnel-related costs largely attributable to an increase in headcount. Personnel-related costs for the nine months ended September 30, 2025 and 2024 included share-based compensation of $20.3 million and $16.7 million, respectively.

Previous wording

For the six months ended June 30, 2025, we recorded an income tax provision of $12.1 million relating primarily to income earned in the UK, Switzerland and the U.S., net of the FDII deduction, benefits related to share-based compensation and R&D Credits utilized. For the six months ended June 30, 2024, we recorded an income tax provision of $9.6 million relating primarily to income earned in the UK, Switzerland and the United States, net of the FDII deduction and R&D Credits.

Current wording

For the nine months ended September 30, 2025, we recorded an income tax provision of $20.8 million relating primarily to income earned in Switzerland, the United States, and the UK, net of benefits related to share-based compensation, R&D Credits, and FDII deduction. For the nine months ended September 30, 2024, we recorded an income tax provision of $15.1 million relating primarily to income earned in the UK, Switzerland and the United States, net of the FDII deduction and R&D Credits.

Previous wording

As of June 30, 2025, our principal source of liquidity was cash, cash equivalents and short-term investments, which totaled $307.8 million. Net income (loss) was $26.4 million and ($21.6) million for the six months ended June 30, 2025 and 2024, respectively. We expect our cash balance and our expected cash inflows from operations to allow us to meet our current operating plan.

Current wording

As of September 30, 2025, our principal source of liquidity was cash, cash equivalents and short-term investments, which totaled $352.1 million. Net income (loss) was $44.8 million and ($34.3) million for the nine months ended September 30, 2025 and 2024, respectively. We expect our cash balance and our expected cash inflows from operations to allow us to meet our current operating plan.

Previous wording

Under various agreements with third parties, we have agreed to make milestone payments, pay royalties, pay annual maintenance fees and to meet due diligence requirements, each based upon specified events. Pursuant to the Regeneron Agreement, we have entered into a supply agreement with Regeneron to purchase both clinical and commercial product. We have committed to minimum payments to Regeneron of $14.2 million, all of which are due within one year. We have entered into lease agreements for office and laboratory space, and vehicles, with total future lease payments of $11.9 million, of which $4.1 million are due within one year. In connection with our ongoing technology transfer of ARCALYST drug substance manufacturing, we have entered into a Master Services Agreement and a Product Specific Agreement with Samsung. Our commitments under such agreements, which include the purchase of raw materials and related service fees, will obligate us to minimum payments of $136.7 million, $0.7 million of which are due within one year. As of June 30, 2025, we have capitalized $18.4 million of production cost into inventory as semi-finished goods related to drug substance manufactured at Samsung. We have additionally entered into agreements with several CDMOs to provide us with preclinical and clinical trial materials for our non-ARCALYST assets, which obligate us to minimum payments of $10.7 million all of which are due within one year. We have long-term incentive plans for our employees that may result in cash award payments of $22.3 million, based upon the achievement of certain regulatory milestones, none of which are expected to be achieved in the next year.

Current wording

Under various agreements with third parties, we have agreed to make milestone payments, pay royalties, pay annual maintenance fees and to meet due diligence requirements, each based upon specified events. Pursuant to the Regeneron Agreement, we have entered into a supply agreement with Regeneron to purchase both clinical and commercial product. We have committed to minimum payments to Regeneron of $56.1 million, all of which are due within one year. We have entered into lease agreements for office and laboratory space, and vehicles, with total future lease payments of $11.7 million, of which $4.1 million are due within one year. In connection with our ongoing technology transfer of ARCALYST drug substance manufacturing, we have entered into a Master Services Agreement and a Product Specific Agreement with Samsung. Our commitments under such agreements, which include the purchase of raw materials and related service fees, will obligate us to minimum payments of $136.9 million, $18.4 million of which are due within one year. As of September 30, 2025, we have capitalized $17.5 million of production cost into inventory as semi-finished goods related to drug substance manufactured at Samsung. We have additionally entered into agreements with several CDMOs to provide us with preclinical and clinical trial materials for our non-ARCALYST assets, which obligate us to minimum payments of $12.0 million all of which are due within one year. We have long-term incentive plans for our employees that may result in cash award payments of $22.6 million, based upon the achievement of certain regulatory milestones, none of which are expected to be achieved in the next year.

Previous wording

Net cash provided by operations was $50.4 million and $9.2 million for the six months ended June 30, 2025 and 2024, respectively. The increase in cash provided by operating activities is primarily due to an increase in net contribution from higher ARCALYST sales and an increase in cash received from licensing agreements of $5.0 million.

Current wording

Net cash provided by operations was $84.1 million and $6.9 million for the nine months ended September 30, 2025 and 2024, respectively. The increase in cash provided by operating activities is primarily due to an increase in net contribution from higher ARCALYST sales and an increase in cash received from licensing agreements of $5.0 million.

Previous wording

Net cash used in investing activities was $55.4 million and $21.3 million for the six months ended June 30, 2025 and 2024, respectively. The increase in net cash used in investing activities was driven by managing our cash and short-term investment portfolio mix.

Current wording

Net cash used in investing activities was $118.2 million and $27.6 million for the nine months ended September 30, 2025 and 2024, respectively. The increase in net cash used in investing activities was driven by managing our cash and short-term investment portfolio mix.

Previous wording

During the six months ended June 30, 2025 and 2024, net cash provided by financing activities was $13.5 million and $3.4 million, respectively, consisting of proceeds from the exercise of share options offset by payments in connection with ordinary shares tendered for employee tax obligations.

Current wording

During the nine months ended September 30, 2025 and 2024, net cash provided by financing activities was $25.4 million and $10.1 million, respectively, consisting of proceeds from the exercise of share options offset by payments in connection with ordinary shares tendered for employee tax obligations.