Kiniksa Pharmaceuticals Reports Fourth Quarter and Full Year 2025 Financial Results and Recent Portfolio Execution

– ARCALYST®(rilonacept) Q4 2025 and full year 2025 net product revenue of $202.1 million and $677.6 million, respectively –– ARCALYST 2026 net product revenue expected to be $900 - $920 million –– KPL-387 Phase 2 recurrent pericarditis data expected in 2H 2026 –– KPL-1161 Phase 1 trial planned to initiate by the end of 2026 –– Cash balance increased by $170.4 million in 2025 to $414.1 million –– Conference call and webcast scheduled for 8:30 am ET today –

LONDON, Feb. 24, 2026 (GLOBE NEWSWIRE) --  –Kiniksa Pharmaceuticals International, plc(Nasdaq: KNSA) (Kiniksa), a biopharmaceutical company developing and commercializing novel therapies for diseases with unmet need, with a focus on cardiovascular indications, today reported fourth quarter and full year 2025 financial results and recent portfolio execution.

“Kiniksa continued to drive significant advancements across its commercial and clinical portfolio in 2025. The expanding adoption of IL-1α & IL-1β inhibition with ARCALYST as the preferred second-line treatment for recurrent pericarditis helped drive 62% year-over-year ARCALYST sales growth to $677.6 million. We believe substantial opportunity remains for ARCALYST and we expect 2026 sales of between $900 and $920 million,” said Sanj K. Patel, Chairman and Chief Executive Officer of Kiniksa. “Within our clinical pipeline, we expanded our leadership in recurrent pericarditis with the initiation of the KPL-387 Phase 2/3 development program, which could provide an important additional treatment option for patients. We also plan to initiate a Phase 1 trial with KPL-1161, an Fc-modified monoclonal antibody IL-1 receptor antagonist by the end of this year. Importantly, Kiniksa has a robust financial profile which supports these efforts and provides the ability to invest in additional value-creating opportunities.”

About KiniksaKiniksa is a biopharmaceutical company dedicated to improving the lives of patients suffering from debilitating diseases by discovering, acquiring, developing, and commercializing novel therapies for diseases with unmet need, with a focus on cardiovascular indications. Kiniksa’s portfolio of assets is based on strong biologic rationale or validated mechanisms and offers the potential for differentiation. For more information, please visitwww.kiniksa.com.

About ARCALYSTARCALYST is a weekly, subcutaneously injected recombinant dimeric fusion protein that blocks interleukin-1 alpha (IL-1α) and interleukin-1 beta (IL-1β) signaling. ARCALYST was discovered by Regeneron Pharmaceuticals, Inc. (Regeneron) and is approved by the U.S. Food and Drug Administration (FDA) for the treatment of recurrent pericarditis (RP) and reduction in risk of recurrence in adults and children 12 years and older. ARCALYST is also approved by the FDA for the treatment of Cryopyrin-Associated Periodic Syndromes (CAPS), including Familial Cold Autoinflammatory Syndrome (FCAS) and Muckle-Wells Syndrome (MWS) in adults and children 12 years and older, and the maintenance of remission of Deficiency of Interleukin-1 Receptor Antagonist (DIRA) in adults and pediatric patients weighing 10 kg or more. The FDA granted Orphan Drug Exclusivity to ARCALYST upon its approval for recurrent pericarditis in 2021. The European Commission granted Orphan Drug Designation to ARCALYST for the treatment of idiopathic pericarditis in 2021.

About KPL-387KPL-387 is an independently developed, investigational, fully human immunoglobulin G2 (IgG2) monoclonal antibody that binds human interleukin-1 receptor 1 (IL-1R1), inhibiting the signaling of the cytokines IL-1α and IL-1β. Kiniksa believes KPL-387 could expand the treatment options for recurrent pericarditis patients by potentially enabling dosing with a single monthly SC self-injection in a liquid formulation. In October 2025, the FDA granted Orphan Drug Designation to KPL-387 for the treatment of pericarditis.

About KPL-1161KPL-1161 is an independently developed, investigational, Fc-modified IgG2 monoclonal antibody that binds IL-1R1, inhibiting the signaling of the cytokines IL-1α and IL-1β, with a target profile of quarterly SC dosing. Kiniksa is currently engaging in preclinical development activities for KPL-1161.

Forward-Looking StatementsThis press release contains forward-looking statements. In some cases, you can identify forward looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these identifying words. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including without limitation, statements regarding: our expectation that ARCALYST 2026 net product revenue will be between $900 million and $920 million; our belief that data from the dose-focusing portion of our Phase 2 clinical trial of KPL-387 in recurrent pericarditis will be available in the second half of 2026; our plan to initiate a Phase 1 first-in-human clinical trial of KPL-1161 by the end of 2026; our belief that KPL-387 could provide an important additional treatment option for recurrent pericarditis patients; our belief that our robust financial profile will provide the ability to invest in additional value creation; our target profile of quarterly subcutaneous dosing for KPL-1161; our beliefs about the mechanisms of our assets and potential impact of their approach; statements regarding our belief about the future of our commercial opportunities; and our belief that our portfolio of assets offers the potential for differentiation.

These forward-looking statements are based on management’s current expectations. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including without limitation, the following: delays or difficulty in enrollment of patients in, and activation or continuation of sites for, our clinical trials; delays or difficulty in completing our clinical trials as originally designed; potential for changes between final data and any preliminary, interim, top-line or other data from clinical trials; our inability to replicate results from our earlier clinical trials or studies; impact of additional data from us or other companies, including the potential for our data to produce negative, inconclusive or commercially uncompetitive results; our reliance on third parties to conduct research, clinical trials, and/or certain regulatory activities for our product candidates; complications in coordinating requirements, regulations and guidelines of regulatory authorities across jurisdictions for our clinical trials; potential undesirable side effects caused by our products and product candidates; our inability to demonstrate safety and efficacy to the satisfaction of applicable regulatory authorities; potential for applicable regulatory authorities to not accept our filings, delay or deny approval of any of our product candidates or require additional data or trials to support approval; our reliance on third parties as the sole source of supply of the drug substance and drug product used in our products and product candidates; raw material, important ancillary product and drug substance and/or drug product shortages; business development activities and their impact on our financial performance and strategy; changes in our operating plan, business development strategy or funding requirements; existing or new competition; current and future healthcare reforms, including those affecting the delivery of or payment for healthcare products and services; and the impact of global economic policy, including any uncertainty in national and international markets.

These and other important factors discussed in our filings with the U.S. Securities and Exchange Commission, including under the caption “Risk Factors” contained therein, could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management’s estimates as of the date of this press release. Except as required by law, we disclaim any intention or obligation to update or revise any forward-looking statements. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this press release.

ARCALYST® is a registered trademark of Regeneron Pharmaceuticals, Inc.

1Q4 2024 and 2024 collaboration expenses included a $10.0 million charge for Regeneron’s share of a $20.0 million milestone received from Huadong Medicine for approval of ARCALYST in China.