Idiopathic Recurrent Pericarditis

– ARCALYST® (rilonacept) Q2 2024 net product revenue of $103.4 million, representing 90% year-over-year growth –– ARCALYST 2024 expected net product revenue increased to $405 - $415 million –– Abiprubart clinical development fully funded; Phase 2b clinical trial in Sjögren’s Disease enrolling patients –– Kiniksa expects to remain cash flow positive on an annual basis –– Conference call and webcast scheduled for 8:30 am ET today – LONDON, July 23, 2024 (GLOBE NEWSWIRE) -- Kiniksa Pharmaceuticals International, plc (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 second quarter 2024 financial results and recent portfolio execution. “Kiniksa’s work to establish ARCALYST as the standard of care in recurrent pericarditis continues to drive the company’s commercial performance. As of the end of the second quarter, ~11% of the 14,000 multiple-recurrence target population were actively on ARCALYST treatment, and total average duration of therapy increased to approximately 26 months. We now expect 2024 ARCALYST net sales to increase to between $405 and $415 million from our previous guidance of between $370 and $390 million,” said Sanj K. Patel, Chairman and Chief Executive Officer of Kiniksa. “Within our pipeline, commencing enrollment in the abiprubart Phase 2b trial in Sjögren’s Disease, a debilitating, chronic autoimmune disease, which currently has no FDA-approved therapies, represents an exciting growth opportunity for the company. Clinical development of abiprubart in Sjögren’s Disease is fully funded in our current operating plan, and we expect to remain cash flow positive on an annual basis.” Portfolio ExecutionARCALYST (IL-1α and IL-1β cytokine trap) ARCALYST net product revenue was $103.4 million for the second quarter of 2024.Since launch in April 2021, more than 2,300 prescribers have written ARCALYST prescriptions for recurrent pericarditis.As of the end of the second quarter of 2024, the average total duration of ARCALYST therapy in recurrent pericarditis increased to approximately 26 months, compared to ~23 months as of the end of the first quarter of 2024.As of the end of the second quarter of 2024, approximately 11% of the target 14,000 multiple-recurrence patients were actively on ARCALYST treatment, compared to ~9% as of the end of 2023.In June 2024, Kiniksa announced its sponsorship of the American Heart Association’s Addressing Recurrent Pericarditis initiative, a multi-faceted effort aimed at improving access to expert care and quality of care for patients with recurrent pericarditis.In June 2024, Kiniksa announced a partnership with National Hockey League Hall-of-Famer, Henrik Lundqvist, to raise awareness in support of patients suffering from recurrent pericarditis. Abiprubart (anti-CD40 monoclonal antibody inhibitor of CD40-CD154 interaction) Kiniksa is enrolling patients in a Phase 2b clinical trial designed to evaluate the efficacy and safety of biweekly and monthly abiprubart administered subcutaneously in patients with Sjögren’s Disease. Financial Results Total revenue for the second quarter of 2024 was $108.6 million, compared to $71.5 million for the second quarter of 2023. Total revenue for the second quarter of 2024 included $5.2 million in license and collaboration revenue, compared to $17.0 million for the second quarter of 2023. Total operating expenses for the second quarter of 2024 were $108.7 million, compared to $74.6 million for the second quarter of 2023. Total operating expenses for the second quarter of 2024 included $30.0 million in collaboration expenses, which are driven by ARCALYST collaboration profitability, compared to $14.0 million for the second quarter of 2023.Total operating expenses for the second quarter of 2024 included $7.4 million in non-cash, share-based compensation expense, compared to $6.5 million for the second quarter of 2023. Net loss for the second quarter of 2024 was $3.9 million, compared to a net income of $15.0 million for the second quarter of 2023.As of June 30, 2024, Kiniksa had $218.8 million of cash, cash equivalents, and short-term investments and no debt. Financial Guidance Kiniksa expects 2024 ARCALYST net product revenue of between $405 million and $415 million, compared to prior guidance of between $370 million and $390 million.Kiniksa expects 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, July 23, 2024, to discuss second 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 KiniksaKiniksa 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 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 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. 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 2024 net product revenue will be between $405 million and $415 million; our expectation that clinical development of abiprubart in Sjögren’s Disease is fully funded in our current operating plan; our expectation to remain cash flow positive on an annual basis; 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; 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; 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 ContactRachel Frank(339) 970-9437rfrank@kiniksa.com KINIKSA PHARMACEUTICALS INTERNATIONAL, PLC(FORMERLY KNOWN AS KINIKSA PHARMACEUTICALS, LTD.)SELECTED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS)(In thousands)(Unaudited) Three Months Ended Six Months Ended June 30, June 30, 2024 2023 2024 2023 Revenue: Product revenue, net $103,394 $54,495 $182,279 $97,154 License and collaboration revenue 5,237 16,978 6,210 22,664 Total revenue 108,631 71,473 188,489 119,818 Costs and operating expenses: Cost of goods sold 12,322 7,699 22,905 14,735 Collaboration expenses 30,014 13,986 50,815 22,274 Research and development 24,017 23,767 50,351 38,939 Selling, general and administrative 42,395 29,175 81,077 58,220 Total operating expenses 108,748 74,627 205,148 134,168 Loss from operations (117) (3,154) (16,659) (14,350)Other income 2,421 1,915 4,687 3,747 Income (loss) before income taxes 2,304 (1,239) (11,972) (10,603)Benefit (provision) for income taxes (6,212) 16,211 (9,640) 13,305 Net income (loss) $(3,908) $14,972 $(21,612) $2,702 Net income (loss) per share attributable to ordinary shareholders—basic $(0.06) $0.21 $(0.31) $0.04 Net income (loss) per share attributable to ordinary shareholders—diluted $(0.06) $0.21 $(0.31) $0.04 Weighted average ordinary shares outstanding—basic 71,004,640 69,918,287 70,818,831 69,835,452 Weighted average ordinary shares outstanding—diluted 71,004,640 71,634,729 70,818,831 71,420,026 KINIKSA PHARMACEUTICALS INTERNATIONAL, PLC(FORMERLY KNOWN AS KINIKSA PHARMACEUTICALS, LTD.)SELECTED CONSOLIDATED BALANCE SHEET DATA(In thousands)(Unaudited) As of June 30, December 31, 2024 2023 Cash, cash equivalents, and short-term investments $218,758 $206,371 Working capital 216,730 212,631 Total assets 542,428 526,322 Accumulated deficit (499,562) (477,950)Total shareholders' equity 435,095 438,839

– 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 - -