CD116

– ARCALYST® (rilonacept) Q4 2024 and full year 2024 net product revenue of $122.5 million and $417.0 million, respectively –– ARCALYST 2025 net product revenue expected to be $560 - $580 million –– KPL-387 Phase 2/3 clinical trial in recurrent pericarditis expected to initiate in mid-2025; Phase 2 data expected in 2H 2026 –– Abiprubart development in Sjögren’s Disease to be discontinued –– Current operating plan expected to remain cash flow positive on an annual basis –– Conference call and webcast scheduled for 8:30 am ET today – LONDON, Feb. 25, 2025 (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 2024 financial results and recent portfolio execution. “Strong commercial execution in 2024 resulted in 79% year-over-year ARCALYST sales growth to $417.0 million. We believe substantial opportunity remains for ARCALYST, and expect 2025 sales of between $560 and $580 million,” said Sanj K. Patel, Chairman and Chief Executive Officer of Kiniksa. “Today, we are excited to announce the development program for KPL-387, which we believe could expand the treatment options for recurrent pericarditis patients by enabling a single monthly subcutaneous injection in a liquid formulation. We have interacted with the FDA and plan to initiate a Phase 2/3 clinical trial of KPL-387 in recurrent pericarditis in mid-2025. In line with our prioritization of cardiovascular indications, we plan to discontinue the development of abiprubart in Sjögren’s Disease. On behalf of our entire organization, I would like to thank the patients, caregivers, and investigators who contributed to our study.” Corporate Update Kiniksa continues to focus development on diseases with unmet need, prioritizing cardiovascular indications. Kiniksa announced today the development of KPL-387 in recurrent pericarditis, with a target profile of monthly subcutaneous (SC) dosing. KPL-387 is a fully human immunoglobulin G2 (IgG2) monoclonal antibody that binds human interleukin-1 receptor 1 (IL-1R1), inhibiting the signaling of the cytokines interleukin-1α (IL-1α) and interleukin-1β (IL-1β). Kiniksa announced today that it is advancing KPL-1161 towards clinical development with a target profile of quarterly SC dosing. KPL-1161 is an Fc-modified IgG2 monoclonal antibody that binds IL-1R1, inhibiting the signaling of the cytokines IL-1α and IL-1β. Kiniksa announced today that it plans to discontinue abiprubart development in Sjögren’s Disease. The company will explore strategic alternatives for the asset. Kiniksa announced today that it has exercised its right to terminate its exclusive license agreement for mavrilimumab with MedImmune. Kiniksa announced today the development of KPL-387 in recurrent pericarditis, with a target profile of monthly subcutaneous (SC) dosing. KPL-387 is a fully human immunoglobulin G2 (IgG2) monoclonal antibody that binds human interleukin-1 receptor 1 (IL-1R1), inhibiting the signaling of the cytokines interleukin-1α (IL-1α) and interleukin-1β (IL-1β). Kiniksa announced today that it is advancing KPL-1161 towards clinical development with a target profile of quarterly SC dosing. KPL-1161 is an Fc-modified IgG2 monoclonal antibody that binds IL-1R1, inhibiting the signaling of the cytokines IL-1α and IL-1β. Kiniksa announced today that it plans to discontinue abiprubart development in Sjögren’s Disease. The company will explore strategic alternatives for the asset. Kiniksa announced today that it has exercised its right to terminate its exclusive license agreement for mavrilimumab with MedImmune. Portfolio Execution ARCALYST (IL-1α and IL-1β cytokine trap) ARCALYST net product revenue was $122.5 million and $417.0 million for the fourth quarter and full year 2024, respectively. Since launch, more than 2,850 prescribers have written ARCALYST prescriptions for recurrent pericarditis. As of the end of the fourth quarter of 2024, average total duration of ARCALYST therapy in recurrent pericarditis was approximately 27 months. As of the end of the fourth quarter of 2024, approximately 13% of the target 14,000 multiple-recurrence patients were actively on ARCALYST treatment. KPL-387 (monoclonal antibody IL-1 receptor antagonist) Kiniksa is conducting a single ascending dose (SAD) and multiple ascending dose Phase 1 clinical trial of KPL-387 in healthy volunteers. Topline data from the SAD portion of the Phase 1 trial support potential monthly SC dosing in recurrent pericarditis. Kiniksa has interacted with the U.S. Food and Drug Administration (FDA) and expects to initiate a Phase 2/3 clinical trial of KPL-387 in recurrent pericarditis in mid-2025, with Phase 2 data expected in the second half of 2026. Topline data from the SAD portion of the Phase 1 trial support potential monthly SC dosing in recurrent pericarditis. KPL-1161 (Fc-modified monoclonal antibody IL-1 receptor antagonist) Kiniksa is conducting Investigational New Drug (IND)-enabling development activities with a target profile of quarterly SC dosing. Financial Results Total revenue for the fourth quarter of 2024 was $122.5 million, compared to $83.4 million for the fourth quarter of 2023. Total revenue for the full year 2024 was $423.2 million, compared to $270.3 million for the full year 2023. Total revenue for the fourth quarter of 2024 did not include any license and collaboration revenue, compared to $12.2 million for the fourth quarter of 2023. Total revenue for the full year 2024 included $6.2 million in license and collaboration revenue, compared to $37.1 million for the full year 2023. Total operating expenses for the fourth quarter of 2024 were $141.8 million, compared to $83.3 million for the fourth quarter of 2023. Total operating expenses for the full year 2024 were $468.9 million, compared to $295.5 million for the full year 2023. Total operating expenses for the fourth quarter of 2024 included $48.2 million in collaboration expenses, which are driven by ARCALYST collaboration profitability, compared to $16.9 million for the fourth quarter of 2023. Total operating expenses for the full year 2024 included $128.3 million in collaboration expenses, compared to $56.5 million for the full year 2023. Total operating expenses for the fourth quarter of 2024 included $8.3 million in non-cash, share-based compensation expense, compared to $7.8 million for the fourth quarter of 2023. Total operating expenses for the full year 2024 included $30.7 million in non-cash, share-based compensation expense, compared to $27.1 million for the full year 2023. Net loss for the fourth quarter of 2024 was $8.9 million, compared to a net income of $25.2 million for the fourth quarter of 2023. Net loss for the full year 2024 was $43.2 million, compared to net income of $14.1 million for the full year 2023. Net loss for the fourth quarter of 2024 included a tax benefit of $8.1 million, compared to a tax benefit of $22.8 million for the fourth quarter of 2023, both primarily due to the treatment of non-cash deferred tax assets. Net loss for the full year 2024 included a tax expense of $7.0 million, compared to a tax benefit of $30.7 million for the full year 2023, both primarily due to the treatment of non-cash deferred tax assets. As of December 31, 2024, Kiniksa had $243.6 million of cash, cash equivalents, and short-term investments and no debt, compared to $206.4 million as of December 31, 2023. Total revenue for the fourth quarter of 2024 did not include any license and collaboration revenue, compared to $12.2 million for the fourth quarter of 2023. Total revenue for the full year 2024 included $6.2 million in license and collaboration revenue, compared to $37.1 million for the full year 2023. Total operating expenses for the fourth quarter of 2024 included $48.2 million in collaboration expenses, which are driven by ARCALYST collaboration profitability, compared to $16.9 million for the fourth quarter of 2023. Total operating expenses for the full year 2024 included $128.3 million in collaboration expenses, compared to $56.5 million for the full year 2023. Total operating expenses for the fourth quarter of 2024 included $8.3 million in non-cash, share-based compensation expense, compared to $7.8 million for the fourth quarter of 2023. Total operating expenses for the full year 2024 included $30.7 million in non-cash, share-based compensation expense, compared to $27.1 million for the full year 2023. Net loss for the fourth quarter of 2024 included a tax benefit of $8.1 million, compared to a tax benefit of $22.8 million for the fourth quarter of 2023, both primarily due to the treatment of non-cash deferred tax assets. Net loss for the full year 2024 included a tax expense of $7.0 million, compared to a tax benefit of $30.7 million for the full year 2023, both primarily due to the treatment of non-cash deferred tax assets. Financial Guidance Kiniksa expects 2025 ARCALYST net product revenue of between $560 million and $580 million. Kiniksa expects its current operating plan to remain cash flow positive on an annual basis. Conference Call Information Kiniksa will host a conference call and webcast at 8:30 a.m. Eastern Time on Tuesday, February 25, 2025, to discuss fourth quarter and full year 2024 financial results and to provide a corporate update. Individuals interested in participating in the call via telephone may register here. Upon registration, all telephone participants will receive a confirmation email detailing how to join the conference call, including the dial-in number along with a unique passcode and registrant ID that can be used to access the call. To access the webcast, please visit the Investors and Media section of Kiniksa’s website. A replay of the event will also be available on Kiniksa’s website within approximately 48 hours after the event. 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 visit www.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. IMPORTANT SAFETY INFORMATION ABOUT ARCALYST ARCALYST may affect your immune system and can lower the ability of your immune system to fight infections. Serious infections, including life-threatening infections and death, have happened in patients taking ARCALYST. If you have any signs of an infection, call your doctor right away. Treatment with ARCALYST should be stopped if you get a serious infection. You should not begin treatment with ARCALYST if you have an infection or have infections that keep coming back (chronic infection). While taking ARCALYST, do not take other medicines that block interleukin-1, such as Kineret® (anakinra), or medicines that block tumor necrosis factor, such as Enbrel® (etanercept), Humira® (adalimumab), or Remicade® (infliximab), as this may increase your risk of getting a serious infection. Talk with your doctor about your vaccine history. Ask your doctor whether you should receive any vaccines before you begin treatment with ARCALYST. Medicines that affect the immune system may increase the risk of getting cancer. Stop taking ARCALYST and call your doctor or get emergency care right away if you have any symptoms of an allergic reaction. Your doctor will do blood tests to check for changes in your blood cholesterol and triglycerides. Common side effects include injection-site reactions (which may include pain, redness, swelling, itching, bruising, lumps, inflammation, skin rash, blisters, warmth, and bleeding at the injection site), upper respiratory tract infections, joint and muscle aches, rash, ear infection, sore throat, and runny nose. For more information about ARCALYST, talk to your doctor and see the Product Information. About KPL-387KPL-387 is an independently developed, investigational, fully human IgG2 monoclonal antibody that binds 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 enabling dosing with a single monthly SC injection in a liquid formulation. 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 IND-enabling development activities for KPL-1161. About AbiprubartAbiprubart is an investigational humanized monoclonal antibody that binds to CD40 and is designed to inhibit the CD40-CD154 (CD40 ligand) interaction, a key T-cell co-stimulatory signal critical for B-cell maturation and immunoglobulin class switching and Type 1 immune responses. Kiniksa believes disrupting the CD40-CD154 co-stimulatory interaction is an attractive approach to addressing multiple autoimmune disease pathologies. Forward-Looking Statements This 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 belief that substantial opportunity remains for ARCALYST and our expectation that ARCALYST 2025 net product revenue will be between $560 million and $580 million; our plan to initiate a Phase 2/3 clinical trial of KPL-387 in recurrent pericarditis in mid-2025, with Phase 2 data expected in the second half of 2026; our plan to discontinue abiprubart development in Sjögren’s Disease and explore strategic alternatives for the asset; our expectation that our current operating plan will remain cash flow positive on an annual basis; our plan to focus development on diseases with unmet need, prioritizing cardiovascular indications; our belief that KPL-387 could expand the treatment options for recurrent pericarditis patients by enabling a single monthly SC injection in a liquid formulation; our target profile of monthly and quarterly dosing for KPL-387 and KPL-1161, respectively; our beliefs about the mechanisms of our assets and potential impact of their approach; 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; 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; 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; business development activities and their impact on our financial performance and strategy; changes in our operating plan, business development strategy or funding requirements; and existing or new competition. 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. Every Second Counts! ® Kiniksa Investor ContactJonathan Kirshenbaum(781) 829-3949jkirshenbaum@kiniksa.com Kiniksa Media ContactTyler Gagnon (781) 431-9100tgagnon@kiniksa.com

– ARCALYST® (rilonacept) Q1 2024 net product revenue of $78.9 million, representing 85% year-over-year growth – – ARCALYST 2024 expected net product revenue increased to $370 - $390 million – – Abiprubart Phase 2b trial in Sjögren’s Disease planned to initiate in 2H 2024 – – Current operating plan expected to remain cash flow positive on an annual basis – – Conference call and webcast scheduled for 8:30 am ET today – HAMILTON, Bermuda, April 23, 2024 (GLOBE NEWSWIRE) -- Kiniksa Pharmaceuticals, Ltd. (Nasdaq: KNSA) (Kiniksa), a commercial-stage biopharmaceutical company with a pipeline of immune-modulating assets designed to target a spectrum of cardiovascular and autoimmune diseases, today reported first quarter 2024 financial results and recent portfolio execution. “One of the drivers of strong ARCALYST growth is an expanding utilization of ARCALYST as a steroid-sparing therapy for patients suffering from recurrent pericarditis. In addition, with continued frequent prescriber engagement and high physician and patient satisfaction, we now expect 2024 ARCALYST net sales to increase from our previous guidance of between $360 and $380 million to $370 and $390 million,” said Sanj K. Patel, Chairman and Chief Executive Officer of Kiniksa. “Additionally, we believe abiprubart has the potential to provide meaningful benefit through convenient subcutaneous dosing, and we plan to initiate a Phase 2b trial in Sjögren’s Disease in the second half of 2024. This continued commercial execution and pipeline advancement is included in our current operating plan, which we expect to remain cash flow positive on an annual basis.” Portfolio Execution ARCALYST (IL-1α and IL-1β cytokine trap) ARCALYST net product revenue was $78.9 million for the first quarter of 2024. Since launch in April 2021, approximately 2,000 prescribers have written ARCALYST prescriptions for recurrent pericarditis. As of the end of the first quarter of 2024, average total duration of ARCALYST therapy in recurrent pericarditis was approximately 23 months. Data from the RESONANCE patient registry were presented at the American College of Cardiology Scientific Session (ACC.24). The data highlight a shift in recurrent pericarditis management by pericarditis-focused cardiologists at 21 academic sites across the US and demonstrate increasing proportional ARCALYST use compared to and in advance of corticosteroids since ARCALYST commercial availability for recurrent pericarditis in 2021. Abiprubart (anti-CD40 monoclonal antibody inhibitor of CD40-CD154 interaction) Kiniksa expects to initiate a Phase 2b trial designed to evaluate the efficacy of biweekly and monthly abiprubart administered subcutaneously in patients with Sjögren’s Disease in the second half of 2024. Mavrilimumab (monoclonal antibody inhibitor targeting GM-CSFRα) Kiniksa is evaluating potential partnership opportunities to advance development of mavrilimumab, which has generated positive data in mid-stage clinical trials across multiple indications. Financial Results Total revenue for the first quarter of 2024 was $79.9 million, compared to $48.3 million for the first quarter of 2023. Total revenue for the first quarter of 2024 included $1.0 million in license and collaboration revenue, compared to $5.7 million for the first quarter of 2023. Total operating expenses for the first quarter of 2024 were $96.4 million, compared to $59.5 million for the first quarter of 2023. Total operating expenses for the first quarter of 2024 included $20.8 million in collaboration expenses, which are driven by ARCALYST collaboration profitability, compared to $8.3 million for the first quarter of 2023. Total operating expenses for the first quarter of 2024, included $7.2 million in non-cash, share-based compensation expense, compared to $6.1 million for the first quarter of 2023. Net loss for the first quarter of 2024 was $17.7 million, compared to a net loss of $12.3 million for the first quarter of 2023. As of March 31, 2024, Kiniksa had $213.6 million of cash, cash equivalents, and short-term investments and no debt. Financial Guidance Kiniksa expects 2024 ARCALYST net product revenue of between $370 million and $390 million, compared to prior guidance of between $360 million and $380 million. Kiniksa expects its current operating plan to remain cash flow positive on an annual basis. Conference Call Information Kiniksa will host a conference call and webcast at 8:30 a.m. Eastern Time on Tuesday, April 23, 2024, to discuss first quarter 2024 financial results and recent portfolio execution. Individuals interested in participating in the call via telephone may register here. Upon registration, all telephone participants will receive a confirmation email detailing how to join the conference call, including the dial-in number along with a unique passcode and registrant ID that can be used to access the call. To access the webcast, please visit the Investors and Media section of Kiniksa’s website. A replay of the event will also be available on Kiniksa’s website within approximately 48 hours after the event. About Kiniksa Kiniksa is a commercial-stage biopharmaceutical company focused on discovering, acquiring, developing, and commercializing therapeutic medicines for patients suffering from debilitating diseases with significant unmet medical need. Kiniksa’s immune-modulating assets, ARCALYST, abiprubart, and mavrilimumab, are based on strong biologic rationale or validated mechanisms, target a spectrum of underserved cardiovascular and autoimmune conditions, and offer the potential for differentiation. For more information, please visit . About ARCALYST ARCALYST 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 recurrent pericarditis, cryopyrin-associated periodic syndromes (CAPS), including Familial Cold Autoinflammatory Syndrome and Muckle-Wells Syndrome, and deficiency of IL-1 receptor antagonist (DIRA). The FDA granted Breakthrough Therapy designation to ARCALYST for the treatment of recurrent pericarditis in 2019 and Orphan Drug exclusivity to ARCALYST in 2021 for the treatment of recurrent pericarditis and reduction in risk of recurrence in adults and pediatric patients 12 years and older. The European Commission granted Orphan Drug Designation to ARCALYST for the treatment of idiopathic pericarditis in 2021. IMPORTANT SAFETY INFORMATION ABOUT ARCALYST ARCALYST may affect your immune system and can lower the ability of your immune system to fight infections. Serious infections, including life-threatening infections and death, have happened in patients taking ARCALYST. If you have any signs of an infection, call your doctor right away. Treatment with ARCALYST should be stopped if you get a serious infection. You should not begin treatment with ARCALYST if you have an infection or have infections that keep coming back (chronic infection). While taking ARCALYST, do not take other medicines that block interleukin-1, such as Kineret® (anakinra), or medicines that block tumor necrosis factor, such as Enbrel® (etanercept), Humira® (adalimumab), or Remicade® (infliximab), as this may increase your risk of getting a serious infection. Talk with your doctor about your vaccine history. Ask your doctor whether you should receive any vaccines before you begin treatment with ARCALYST. Medicines that affect the immune system may increase the risk of getting cancer. Stop taking ARCALYST and call your doctor or get emergency care right away if you have any symptoms of an allergic reaction. Your doctor will do blood tests to check for changes in your blood cholesterol and triglycerides. Common side effects include injection-site reactions (which may include pain, redness, swelling, itching, bruising, lumps, inflammation, skin rash, blisters, warmth, and bleeding at the injection site), upper respiratory tract infections, joint and muscle aches, rash, ear infection, sore throat, and runny nose. For more information about ARCALYST, talk to your doctor and see the Product Information. About Abiprubart Abiprubart is an investigational humanized monoclonal antibody that binds to CD40 and is designed to inhibit the CD40-CD154 (CD40 ligand) interaction, a key T-cell co-stimulatory signal critical for B-cell maturation and immunoglobulin class switching and Type 1 immune responses. Kiniksa believes disrupting the CD40-CD154 co-stimulatory interaction is an attractive approach to addressing multiple autoimmune disease pathologies. About Mavrilimumab Mavrilimumab is an investigational fully human monoclonal antibody that blocks activity of GM-CSF by specifically binding to the alpha subunit of the GM-CSF receptor (GM-CSFRα). Phase 2 clinical trials of mavrilimumab in rheumatoid arthritis and giant cell arteritis achieved their primary and secondary endpoints with statistical significance. Kiniksa is evaluating potential partnership opportunities for mavrilimumab. Forward-Looking Statements This 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 2024 net product revenue will be between $370 million and $390 million; our plan to initiate a Phase 2b clinical trial of abiprubart in Sjögren’s Disease in the second half of 2024; our expectation to remain cash flow positive on an annual basis within our current operating plan; future clinical trial design, including the design of our planned Phase 2b trial of abiprubart in Sjögren’s Disease; our beliefs about the mechanisms of our product candidates and potential impact of their approach, including that using abiprubart to disrupt the CD40-CD154 co-stimulatory interaction is an attractive approach to address multiple autoimmune disease pathologies; and our belief that all of our product candidates offer 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: risks arising from the planned redomiciliation of our principal holding company from Bermuda to the United Kingdom; 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; 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 product candidates; raw material, important ancillary product and drug substance and/or drug product shortages; 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; changes in our operating plan, business development strategy or funding requirements; and existing or new competition. 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. Every Second Counts! ® Kiniksa Investor and Media Contact Rachel Frank (339) 970-9437 rfrank@kiniksa.com KINIKSA PHARMACEUTICALS, LTD. CONSOLIDATED STATEMENTS OF OPERATIONS (In thousands, except share and per share amounts) (Unaudited) Three Months Ended March 31, 2024 2023 Revenue: Product revenue, net $ 78,885 $ 42,659 License and collaboration revenue 973 5,686 Total revenue 79,858 48,345 Operating expenses: Cost of goods sold 10,583 7,036 Collaboration expenses 20,801 8,288 Research and development 26,334 15,172 Selling, general and administrative 38,682 29,045 Total operating expenses 96,400 59,541 Loss from operations (16,542 ) (11,196 ) Other income 2,266 1,832 Loss before income taxes (14,276 ) (9,364 ) Provision for income taxes (3,428 ) (2,906 ) Net loss $ (17,704 ) $ (12,270 ) Net loss per share attributable to common shareholders —basic and diluted $ (0.25 ) $ (0.18 ) Weighted average common shares outstanding—basic and diluted 70,633,023 69,751,697 KINIKSA PHARMACEUTICALS, LTD. SELECTED CONSOLIDATED BALANCE SHEET DATA (In thousands) (Unaudited) As of March 31, December 31, 2024 2023 Cash, cash equivalents, and short-term investments $ 213,552 $ 206,371 Working capital 206,379 212,631 Total assets 519,673 526,322 Accumulated deficit (495,654 ) (477,950 ) Total shareholders' equity 431,895 438,839

– ARCALYST® (rilonacept) Q4 2023 and full-year 2023 net product revenue of $71.2 million and $233.2 million, respectively – – ARCALYST 2024 net product revenue expected to be $360 - $380 million, representing ~59% year-over-year growth at the midpoint – – Abiprubart Phase 2 rheumatoid arthritis data from Cohort 4 and a new development indication expected in April 2024 – – Cash reserves of $206.4 million expected to fund operations into at least 2027 – – Conference call and webcast scheduled for 8:30 am ET today – HAMILTON, Bermuda, Feb. 28, 2024 (GLOBE NEWSWIRE) -- Kiniksa Pharmaceuticals, Ltd. (Nasdaq: KNSA) (Kiniksa), a commercial-stage biopharmaceutical company with a pipeline of immune-modulating assets designed to target a spectrum of cardiovascular and autoimmune diseases, today reported fourth quarter and full-year 2023 financial results and recent portfolio execution. “Kiniksa meaningfully advanced its business in 2023, primarily through robust ARCALYST net product revenue and collaboration profit growth. Significant growth remains with ARCALYST in recurrent pericarditis, and we expect to help an increasing number of patients in the years ahead. Importantly, we anticipate our robust commercial performance to contribute to our strong financial position and ability to drive growth across our business,” said Sanj K. Patel, Chairman and Chief Executive Officer of Kiniksa. “Additionally, abiprubart recently showed clinical effect in the first three cohorts of the Phase 2 trial in rheumatoid arthritis. We now expect to advance the asset into a Phase 2b trial in a new indication, funding for which is included in our current cash runway guidance. Data from the fourth cohort of the abiprubart Phase 2 trial are intended to inform trial design and are expected in April.” Portfolio and Collaboration Execution ARCALYST (IL-1α and IL-1β cytokine trap) ARCALYST net product revenue was $71.2 million and $233.2 million for the fourth quarter and full-year 2023, respectively. Since launch in April 2021, more than 1,700 prescribers have written ARCALYST prescriptions for recurrent pericarditis. As of the end of the fourth quarter of 2023, average total duration of ARCALYST therapy in recurrent pericarditis had increased to approximately 23 months. As of the end of the fourth quarter of 2023, approximately 9% of the target 14,000 multiple-recurrence patients were actively on ARCALYST treatment. A poster entitled Rilonacept Utilization in a Steroid-Sparing Paradigm for Recurrent Pericarditis: Real-World Evidence Demonstrating Increased Adoption is planned to be presented at the upcoming American College of Cardiology Scientific Session (ACC.24) in April 2024. Abiprubart (anti-CD40 monoclonal antibody inhibitor of CD40-CD154 interaction) Kiniksa previously announced topline data from the Phase 2 clinical trial of abiprubart in rheumatoid arthritis, showing that the trial met its primary efficacy endpoint: change from baseline in Disease Activity Score of 28 Joints Using C-reactive Protein (DAS28-CRP) versus placebo. In Cohorts 1 and 2 (pharmacokinetic lead-in), multiple doses of abiprubart were well-tolerated. In Cohort 3, the abiprubart 5 mg/kg subcutaneous (SC) weekly dose level achieved statistical significance. The 5 mg/kg SC biweekly dose level did not achieve statistical significance. Across both dose levels abiprubart reduced Rheumatoid Factor, a clinical marker of disease activity and an autoantibody pharmacodynamic marker of CD40 target engagement. Abiprubart was well-tolerated, with no dose-related adverse experiences observed. Kiniksa expects data from the fourth cohort (Cohort 4) of the Phase 2 clinical trial in April 2024. Cohort 4 will evaluate a fixed dose level administered as a single subcutaneous injection once monthly. Mavrilimumab (monoclonal antibody inhibitor targeting GM-CSFRα) Kiniksa is evaluating potential partnership opportunities to advance development of mavrilimumab, which has generated positive data in mid-stage clinical trials across multiple indications. Vixarelimab (monoclonal antibody inhibitor of signaling through OSMRβ) In the fourth quarter of 2023, Kiniksa recognized a $10.0 million development milestone related to a second new indication under its global license agreement with Genentech, a member of the Roche Group. Financial Results Total revenue for the fourth quarter of 2023 was $83.4 million, compared to $61.9 million for the fourth quarter of 2022. Total revenue for the full-year 2023 was $270.3 million, compared to $220.2 million for the full-year 2022. Total revenue for the fourth quarter of 2023 included $12.2 million in license and collaboration revenue, compared to $21.9 million for the fourth quarter of 2022. Total revenue for the full-year 2023 included $37.1 million in license and collaboration revenue, compared to $97.7 million for the full-year 2022. Total operating expenses for the fourth quarter of 2023 were $83.3 million, compared to $55.8 million for the fourth quarter of 2022. Total operating expenses for the full-year 2023 were $295.5 million, compared to $210.4 million for the full-year 2022. Total operating expenses for the fourth quarter of 2023 included $16.9 million in collaboration expenses, which are driven by ARCALYST collaboration profitability, compared to $7.5 million for the fourth quarter of 2022. Total operating expenses for the full-year 2023 included $56.5 million in collaboration expenses, compared to $24.1 million for the full-year 2022. Total operating expenses for the fourth quarter of 2023 included $7.8 million in non-cash, share-based compensation expense, compared to $6.4 million for the fourth quarter of 2022. Total operating expense for the full-year 2023 included $27.1 million in non-cash, share-based compensation expense, compared to $25.1 million for the full-year 2022. Net income for the fourth quarter of 2023 was $25.2 million, compared to net income of $4.5 million for the fourth quarter of 2022. Net income for the full-year 2023 was $14.1 million, compared to net income of $183.4 million for the full-year 2022. Net income for the fourth quarter of 2023 included a tax benefit of $22.8 million, primarily due to the treatment of non-cash deferred tax assets, compared to a tax expense of $2.4 million for the fourth quarter of 2022. Net income for the full-year 2023 included a tax benefit of $30.7 million, compared to a tax benefit of $172.3 million for the full-year 2022, both primarily due to the treatment of non-cash deferred tax assets. As of December 31, 2023, Kiniksa had $206.4 million of cash, cash equivalents, and short-term investments and no debt. Financial Guidance Kiniksa expects 2024 ARCALYST net product revenue of between $360 million and $380 million. Kiniksa expects that its cash, cash equivalents, and short-term investments will fund its current operating plan into at least 2027. Conference Call Information Kiniksa will host a conference call and webcast at 8:30 a.m. Eastern Time on Wednesday, February 28, 2024, to discuss fourth quarter and full-year 2023 financial results and recent portfolio execution. Individuals interested in participating in the call via telephone may register here. Upon registration, all telephone participants will receive a confirmation email detailing how to join the conference call, including the dial-in number along with a unique passcode and registrant ID that can be used to access the call. To access the webcast, please visit the Investors and Media section of Kiniksa’s website. A replay of the event will also be available on Kiniksa’s website within approximately 48 hours after the event. About Kiniksa Kiniksa is a commercial-stage biopharmaceutical company focused on discovering, acquiring, developing, and commercializing therapeutic medicines for patients suffering from debilitating diseases with significant unmet medical need. Kiniksa’s immune-modulating assets, ARCALYST, abiprubart, and mavrilimumab, are based on strong biologic rationale or validated mechanisms, target a spectrum of underserved cardiovascular and autoimmune conditions, and offer the potential for differentiation. For more information, please visit . About ARCALYST ARCALYST 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 recurrent pericarditis, cryopyrin-associated periodic syndromes (CAPS), including Familial Cold Autoinflammatory Syndrome and Muckle-Wells Syndrome, and deficiency of IL-1 receptor antagonist (DIRA). The FDA granted Breakthrough Therapy designation to ARCALYST for the treatment of recurrent pericarditis in 2019 and Orphan Drug exclusivity to ARCALYST in 2021 for the treatment of recurrent pericarditis and reduction in risk of recurrence in adults and pediatric patients 12 years and older. The European Commission granted Orphan Drug Designation to ARCALYST for the treatment of idiopathic pericarditis in 2021. IMPORTANT SAFETY INFORMATION ABOUT ARCALYST ARCALYST may affect your immune system and can lower the ability of your immune system to fight infections. Serious infections, including life-threatening infections and death, have happened in patients taking ARCALYST. If you have any signs of an infection, call your doctor right away. Treatment with ARCALYST should be stopped if you get a serious infection. You should not begin treatment with ARCALYST if you have an infection or have infections that keep coming back (chronic infection). While taking ARCALYST, do not take other medicines that block interleukin-1, such as Kineret® (anakinra), or medicines that block tumor necrosis factor, such as Enbrel® (etanercept), Humira® (adalimumab), or Remicade® (infliximab), as this may increase your risk of getting a serious infection. Talk with your doctor about your vaccine history. Ask your doctor whether you should receive any vaccines before you begin treatment with ARCALYST. Medicines that affect the immune system may increase the risk of getting cancer. Stop taking ARCALYST and call your doctor or get emergency care right away if you have any symptoms of an allergic reaction. Your doctor will do blood tests to check for changes in your blood cholesterol and triglycerides. Common side effects include injection-site reactions (which may include pain, redness, swelling, itching, bruising, lumps, inflammation, skin rash, blisters, warmth, and bleeding at the injection site), upper respiratory tract infections, joint and muscle aches, rash, ear infection, sore throat, and runny nose. For more information about ARCALYST, talk to your doctor and see the Product Information. About Abiprubart Abiprubart is an investigational humanized monoclonal antibody that binds to CD40 and is designed to inhibit the CD40-CD154 (CD40 ligand) interaction, a key T-cell co-stimulatory signal critical for B-cell maturation and immunoglobulin class switching and Type 1 immune responses. Kiniksa believes disrupting the CD40-CD154 co-stimulatory interaction is an attractive approach to addressing multiple autoimmune disease pathologies. About Mavrilimumab Mavrilimumab is an investigational fully human monoclonal antibody that blocks activity of GM-CSF by specifically binding to the alpha subunit of the GM-CSF receptor (GM-CSFRα). Phase 2 clinical trials of mavrilimumab in rheumatoid arthritis and giant cell arteritis achieved their primary and secondary endpoints with statistical significance. Kiniksa is evaluating potential partnership opportunities for mavrilimumab. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. 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 2024 net product revenue will be between $360 million and $380 million; our plan to report data from Cohort 4 of our Phase 2 clinical trial of abiprubart in rheumatoid arthritis and a new development indication for abiprubart in April 2024; our expectation about our cash reserves funding our current operating plan into at least 2027; our expectation that we will help an increasing number of patients in the future; our plan to develop abiprubart in an additional indication; our plan to present a poster at the upcoming American College of Cardiology Scientific Session in April 2024; our beliefs about the mechanisms of our product candidates and potential impact of their approach, including that using abiprubart to disrupt the CD40-CD154 co-stimulatory interaction is an attractive approach to address multiple autoimmune disease pathologies; and our belief that all of our product candidates offer 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; 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; inability to successfully execute on our commercial strategy for ARCALYST; 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; our reliance on Regeneron as the current sole manufacturer of ARCALYST; risks arising from our ongoing technology transfer of ARCALYST drug substance manufacturing; raw material, important ancillary product and drug substance and/or drug product shortages; 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; changes in our operating plan, business development strategy or funding requirements; and existing or new competition. 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. All other trademarks are the property of their respective owners. Every Second Counts! ® Kiniksa Investor and Media Contact Rachel Frank (339) 970-9437 rfrank@kiniksa.com KINIKSA PHARMACEUTICALS, LTD. CONSOLIDATED STATEMENTS OF OPERATIONS (In thousands, except share and per share amounts) (Unaudited) Three Months Ended Years Ended December 31, December 31, 2023 2022 2023 2022 Revenue: Product revenue, net $ 71,220 $ 39,939 $ 233,176 $ 122,524 License and collaboration revenue 12,175 21,945 37,083 97,656 Total revenue 83,395 61,884 270,259 220,180 Operating expenses: Cost of goods sold 9,584 6,710 33,407 22,895 Collaboration expenses 16,939 7,522 56,524 24,071 Research and development 20,052 14,390 76,097 65,490 Selling, general and administrative 36,739 27,215 129,427 97,951 Total operating expenses 83,314 55,837 295,455 210,407 Income (loss) from operations 81 6,047 (25,196 ) 9,773 Other income 2,369 794 8,544 1,253 Income (loss) before income taxes 2,450 6,841 (16,652 ) 11,026 Benefit (provision) for income taxes 22,787 (2,380 ) 30,736 172,337 Net income $ 25,237 $ 4,461 $ 14,084 $ 183,363 Net income per share attributable to common shareholders—basic $ 0.36 $ 0.06 $ 0.20 $ 2.64 Net income per share attributable to common shareholders—diluted 0.35 0.06 0.20 2.60 Weighted average common shares outstanding—basic 70,371,601 69,609,342 70,058,952 69,382,275 Weighted average common shares outstanding—diluted 72,660,171 71,369,394 71,922,915 70,421,322 KINIKSA PHARMACEUTICALS, LTD. SELECTED CONSOLIDATED BALANCE SHEET DATA (In thousands) (Unaudited) As of December 31, December 31, 2023 2022 Cash, cash equivalents, and short-term investments $ 206,371 $ 190,608 Working capital 212,631 195,994 Total assets 526,322 459,672 Accumulated deficit (477,950 ) (492,034 ) Total shareholders' equity 438,839 396,149 - -