Deficiency of Interleukin-1 Receptor Antagonist

- Named Patient Program supports patient access to ARCALYST® (rilonacept) in countries where ARCALYST is not currently commercially available - HAMILTON, Bermuda, Aug. 16, 2021 (GLOBE NEWSWIRE) -- Kiniksa Pharmaceuticals, Ltd. (Nasdaq: KNSA) (“Kiniksa”), a biopharmaceutical company with a portfolio of assets designed to modulate immunological pathways across a spectrum of diseases, today announced the launch of a Named Patient Program for ARCALYST, a weekly, subcutaneously-injected, recombinant fusion protein that blocks interleukin-1 alpha (IL-1α) and interleukin-1 beta (IL-1β) signaling. The Named Patient Program for ARCALYST was launched in partnership with the specialist services company, WEP Clinical. The program is designed to ensure that physicians outside the U.S. can request ARCALYST on behalf of individual patients who have recurrent pericarditis, cryopyrin-associated periodic syndromes (CAPS), or deficiency of IL-1 receptor antagonist (DIRA) but reside in countries where ARCALYST is not currently commercially available. “We are pleased to have launched Kiniksa’s Named Patient Program for ARCALYST, which is designed to facilitate broader access to this much-needed therapeutic option,” said Sanj K. Patel, Chief Executive Officer and Chairman of the Board of Kiniksa. “Recurrent pericarditis, CAPS and DIRA are rare autoinflammatory diseases with limited treatment options and we are pleased to be able to take this step to support additional patients in need outside the U.S.” For physicians who are interested in further information or who would like to request access to the ARCALYST Named Patient Program, please contact: rilonacept@wepclinical.com. About KiniksaKiniksa is a biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutic medicines for patients suffering from debilitating diseases with significant unmet medical need. Kiniksa’s portfolio of assets, ARCALYST, mavrilimumab, vixarelimab and KPL-404, are based on strong biologic rationale or validated mechanisms, target underserved conditions and offer the potential for differentiation. These assets are designed to modulate immunological pathways across a spectrum of diseases. For more information, please visit . About WEP ClinicalEstablished in 2008, WEP Clinical is a specialist services company that works with drug developers to help patients and physicians gain early access to medicines when no other treatment options are available. WEP Clinical has offices located in London, United Kingdom; RTP North Carolina, United States; Lisbon, Portugal; and Dublin, Ireland and possesses all the necessary licenses allowing it to meet drug access and distribution needs across all regions, worldwide. WEP Clinical is passionate about helping those in need. For more information, please visit . About ARCALYSTARCALYST is a weekly, subcutaneously-injected recombinant dimeric fusion protein that blocks interleukin-1 alpha and interleukin-1 beta signaling. ARCALYST was discovered by Regeneron Pharmaceuticals, Inc. and is approved by the U.S. Food and Drug Administration (FDA) for recurrent pericarditis, CAPS, including Familial Cold Autoinflammatory Syndrome and Muckle-Wells Syndrome, and DIRA. The FDA granted Breakthrough Therapy designation to ARCALYST for the treatment of recurrent pericarditis in 2019 and Orphan Drug designation to ARCALYST for the treatment of pericarditis in 2020. The European Commission granted Orphan Drug Designation to ARCALYST for the treatment of idiopathic pericarditis in 2020. About Recurrent PericarditisRecurrent pericarditis is a painful and debilitating autoinflammatory cardiovascular disease that typically presents with chest pain and is often associated with changes in electrical conduction and sometimes buildup of fluid around the heart, called pericardial effusion. Patients who have additional pericarditis episodes following a symptom-free period of 4-6 weeks are identified as having recurrent pericarditis. Recurrent pericarditis symptoms have an impact on quality of life, limit physical activities, and lead to frequent emergency department visits and hospitalizations. Data show that approximately 40,000 patients in the U.S. seek and receive treatment for recurrent pericarditis each year. Of that group, approximately 14,000 patients experience a second or subsequent event (recurrence) due to persistent underlying disease or inadequate response to conventional therapies, such as nonsteroidal anti-inflammatory drugs (NSAIDs), colchicine and corticosteroids. Important information about ARCALYST Injection For more information about ARCALYST, talk to your doctor and see the Product Information. Forward-Looking StatementsThis 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,” “strategy,” 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 the Named Patient Program will provide broader access to ARCALYST through our partnership with WEP Clinical, including allowing physicians to gain early access to ARCALYST on behalf of individual patients with recurrent pericarditis, CAPS or DIRA outside of the United States; our beliefs about the mechanisms of action of our products and product candidates and that 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: our reliance on third parties as the sole source of supply of the drug substance and drug products used in our products and product candidates; our reliance on Regeneron as the sole manufacturer of ARCALYST; our reliance on third parties to manufacture our product candidates; drug substance and/or drug product shortages; our reliance on WEP Clinical to conduct our Named Patient Program; delays, difficulty or inability to successfully execute on our Named Patient Program; the impact of the ongoing COVID-19 pandemic and measures taken in response to the pandemic on our business and operations as well as the business and operations of our manufacturers and other third parties with whom we conduct business or otherwise engage, including regulatory authorities; changes in our operating plan and funding requirements; and existing or new competition. These and other important factors discussed in our filings with the U.S. Securities and Exchange Commission (the “SEC”), 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. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change, except as required by law. 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. All other trademarks are the property of their respective owners. Every Second Counts!™ Kiniksa Investor and Media ContactRachel Frank (339) 970-9437rfrank@kiniksa.com

- Q2 2021 ARCALYST® (rilonacept) net revenue of $7.7 million with greater than 100 prescribing physicians - - Phase 3 data from mavrilimumab clinical trial in COVID-19-related ARDS on-track for Q1 2022; new Phase 2 data demonstrate persistent clinical effect through Day 90 - - Initiation of KPL-404 Phase 2 proof-of-concept clinical trial expected in Q4 2021 - - Conference call and webcast scheduled for 8:30 a.m. ET today - HAMILTON, Bermuda, Aug. 03, 2021 (GLOBE NEWSWIRE) -- Kiniksa Pharmaceuticals, Ltd. (Nasdaq: KNSA) (“Kiniksa”), a biopharmaceutical company with a portfolio of assets designed to modulate immunological pathways across a spectrum of diseases, today reported second quarter 2021 financial results and recent corporate and portfolio activity. “Our commercial team is doing a superb job with the launch of ARCALYST in recurrent pericarditis,” said Sanj K. Patel, Chief Executive Officer and Chairman of the Board of Kiniksa. “Feedback received from physicians and patients highlights the transformational potential of ARCALYST for patients suffering from recurrent pericarditis. We have seen strong uptake and look forward to using this momentum to accelerate broader adoption across this underserved population.” “We are executing on the development of our clinical-stage pipeline,” said John F. Paolini, MD, PhD, Chief Medical Officer of Kiniksa. “The potential broad utility of mavrilimumab across multiple indications is increasingly promising, and we expect data from our Phase 3 clinical trial in COVID-19-related ARDS in the first quarter of 2022. We are enrolling a Phase 2b clinical trial of vixarelimab in prurigo nodularis and believe vixarelimab has the potential to make a meaningful impact on these patients’ lives by addressing both the pruritus and the skin nodules associated with this devastating disease. KPL-404, our anti-CD40 program, has potential across a range of autoimmune diseases, and we plan to initiate a Phase 2 proof-of-concept clinical trial in rheumatoid arthritis in the fourth quarter of this year.” Portfolio Activity ARCALYST (IL-1α and IL-1β cytokine trap) ARCALYST net revenue in the second quarter of 2021 was $7.7 million. The second quarter of 2021 represented Kiniksa’s first quarter of ARCALYST sales. ARCALYST became commercially available through Kiniksa on April 1st, 2021. Greater than 100 physicians who did not participate in Phase 3 RHAPSODY prescribed ARCALYST to at least one recurrent pericarditis patient. Greater than 65% of all recurrent pericarditis enrollments came from physicians practicing outside of the 12 Phase 3 RHAPSODY clinical trial sites in the U.S. Greater than 90% of completed new patient enrollment cases were approved for coverage under the payer medical exceptions process. Kiniksa continues to expect that the majority of payers will establish coverage policies within six months and that almost all payers will update their coverage policies within a year from launch. Kiniksa OneConnectTM provided access, initiation and ongoing support for existing ARCALYST cryopyrin-associated periodic syndromes (CAPS) and deficiency of IL-1 receptor antagonist (DIRA) patients transitioning to Kiniksa product as well as new ARCALYST patients for all approved indications. Mavrilimumab (monoclonal antibody inhibitor targeting GM-CSFRα) Kiniksa’s interactions with the U.S. Food and Drug Administration (FDA) resulted in defined paths for Phase 3 development of mavrilimumab in COVID-19-related acute respiratory distress syndrome (ARDS) and in giant cell arteritis (GCA). Kiniksa today announced additional data from the Phase 2 portion of the Phase 2/3 clinical trial of mavrilimumab in patients with severe COVID-19-related ARDS. Follow-up overall survival data from the cohort of non-mechanically ventilated patients through Day 90 demonstrated persistent clinical effect, confirming and extending the previously-reported Day 29 data. Day 29 data from the cohort of mechanically-ventilated patients did not show a reduction in death. Kiniksa continues to enroll non-mechanically ventilated patients in the Phase 3 clinical trial of mavrilimumab in COVID-19-related ARDS. Kiniksa discontinued enrolling mechanically-ventilated patients in the Phase 3 trial. Kiniksa expects data from the Phase 3 trial in non-mechanically-ventilated patients in the first quarter of 2022. Follow-up overall survival data from the cohort of non-mechanically ventilated patients through Day 90 demonstrated persistent clinical effect, confirming and extending the previously-reported Day 29 data. Day 29 data from the cohort of mechanically-ventilated patients did not show a reduction in death. Kiniksa discontinued enrolling mechanically-ventilated patients in the Phase 3 trial. Kiniksa expects data from the Phase 3 trial in non-mechanically-ventilated patients in the first quarter of 2022. Vixarelimab (monoclonal antibody inhibitor of signaling through OSMRβ) Kiniksa continues to enroll patients in a placebo-controlled Phase 2b clinical trial of vixarelimab in prurigo nodularis, evaluating a range of once-monthly dose regimens via subcutaneous (SC) injection. The primary efficacy endpoint is the percent change from baseline in the weekly-average Worst-Itch Numeric Rating Scale at Week 16. The primary efficacy endpoint is the percent change from baseline in the weekly-average Worst-Itch Numeric Rating Scale at Week 16. KPL-404 (monoclonal antibody inhibitor of the CD40 and CD154 interaction) Kiniksa plans to initiate a placebo-controlled Phase 2 proof-of-concept clinical trial of KPL-404 in rheumatoid arthritis in the fourth quarter of 2021. The planned trial is designed to provide safety data, pharmacokinetic characterization, and efficacy of chronic SC dosing over 12 weeks. Rheumatoid arthritis was selected for demonstration of KPL-404 proof of concept as it is a well-characterized autoimmune disease with decades of published clinical data across diverse mechanistic classes, allowing for objective evaluation in established endpoints. The pharmacokinetic lead-in of the planned trial supports characterization of chronic administration of KPL-404 in a patient population and provides optionality to evaluate the therapeutic potential of KPL-404 across a range of other autoimmune diseases with pathologies believed to be mediated by the CD40-CD154 pathway. The planned trial is designed to provide safety data, pharmacokinetic characterization, and efficacy of chronic SC dosing over 12 weeks. Rheumatoid arthritis was selected for demonstration of KPL-404 proof of concept as it is a well-characterized autoimmune disease with decades of published clinical data across diverse mechanistic classes, allowing for objective evaluation in established endpoints. The pharmacokinetic lead-in of the planned trial supports characterization of chronic administration of KPL-404 in a patient population and provides optionality to evaluate the therapeutic potential of KPL-404 across a range of other autoimmune diseases with pathologies believed to be mediated by the CD40-CD154 pathway. Upcoming Scientific Conference Presentations Kiniksa plans to present additional data from RHAPSODY, the pivotal Phase 3 trial of rilonacept, as well as the study design of the RESONANCE Registry, at the European Society of Cardiology virtual congress, which will be held August 27, 2021 through August 30, 2021. Details of the poster presentations are as follows: Antonio Brucato, MD, Department of Biomedical and Clinical Science, University of Milan, Fatebenefratelli Hospital, Milan, will present a poster entitled, Health-Related Quality of Life in Patients with Recurrent Pericarditis: Results from RHAPSODY, a Phase 3 Study of Rilonacept. Alison Reid, PhD, Kiniksa Pharmaceuticals Corp., will present a poster entitled, RESONANCE Registry: Rationale and Design of the Retrospective and Prospective Longitudinal, Observational Registry in Pediatric and Adult Patients with Recurrent Pericarditis. Antonio Brucato, MD, Department of Biomedical and Clinical Science, University of Milan, Fatebenefratelli Hospital, Milan, will present a poster entitled, Health-Related Quality of Life in Patients with Recurrent Pericarditis: Results from RHAPSODY, a Phase 3 Study of Rilonacept. Alison Reid, PhD, Kiniksa Pharmaceuticals Corp., will present a poster entitled, RESONANCE Registry: Rationale and Design of the Retrospective and Prospective Longitudinal, Observational Registry in Pediatric and Adult Patients with Recurrent Pericarditis. Financial Results Total revenue in the second quarter of 2021 was $7.7 million. Second quarter 2021 revenue is related to product sales for ARCALYST, which became commercially available through Kiniksa on April 1, 2021. Kiniksa did not generate product revenue in the second quarter of 2020. Net loss for the second quarter of 2021 was $41.6 million, compared to a net loss of $37.5 million for the second quarter of 2020. Total operating expenses for the second quarter of 2021 were $48.3 million, compared to $31.9 million for the second quarter of 2020. Non-cash, share-based compensation expense for the second quarter of 2021 was $5.7 million, compared to $4.9 million for the second quarter of 2020. As of June 30, 2021, the company had cash, cash equivalents and short-term investments of $225.9 million and no debt. Non-cash, share-based compensation expense for the second quarter of 2021 was $5.7 million, compared to $4.9 million for the second quarter of 2020. Financial Guidance Kiniksa expects ARCALYST net revenue for the third quarter of 2021 to be between $9.0 million and $10.0 million. Kiniksa expects that its cash, cash equivalents and short-term investments will fund its current operating plan into 2023. Conference Call Information Kiniksa will host a conference call and webcast at 8:30 a.m. Eastern Time on Tuesday, August 3, 2021 to discuss second quarter 2021 financial results and recent corporate and portfolio activity. Individuals interested in participating in the call should dial (866) 614-0636 (U.S. and Canada) or (409) 231-2053 (international) using conference ID number 1485623. To access the webcast, please visit the Investors and Media section of Kiniksa’s website at www.kiniksa.com. The archived webcast will be available on Kiniksa’s website for 14 days beginning approximately one hour after the call has completed. About Kiniksa Kiniksa is a biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutic medicines for patients suffering from debilitating diseases with significant unmet medical need. Kiniksa’s portfolio of assets, ARCALYST, mavrilimumab, vixarelimab and KPL-404, are based on strong biologic rationale or validated mechanisms, target underserved conditions and offer the potential for differentiation. These assets are designed to modulate immunological pathways across a spectrum of diseases. For more information, please visit www.kiniksa.com. About ARCALYST ARCALYST is a weekly, subcutaneously-injected recombinant dimeric fusion protein that blocks interleukin-1 alpha and interleukin-1 beta signaling. ARCALYST was discovered by Regeneron and is approved by the FDA for recurrent pericarditis, CAPS, including Familial Cold Autoinflammatory Syndrome and Muckle-Wells Syndrome, and DIRA. The FDA granted Breakthrough Therapy designation to ARCALYST for the treatment of recurrent pericarditis in 2019 and Orphan Drug designation to ARCALYST for the treatment of pericarditis in 2020. The European Commission granted Orphan Drug designation to ARCALYST for the treatment of idiopathic pericarditis in 2020. Important Information About ARCALYST Injection ARCALYST can 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. You should not begin ARCALYST if you have an infection or have infections that keep coming back. After starting ARCALYST, if you get an infection or show any sign of an infection, including a fever, cough, flu-like symptoms, or have any open sores on your body, call your doctor right away. Treatment with ARCALYST should be stopped if you get a serious infection. ARCALYST should not be started if you have an infection that keeps coming back. 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. Before starting ARCALYST, tell your doctor if you think you have an infection, are being treated for an infection, have signs of an infection, have any open sores, have a history of infections that keep coming back, have asthma, have diabetes or an immune system problem, have tuberculosis, or have been in contact with someone who has had tuberculosis, has or has had HIV, hepatitis B or hepatitis C, or takes other medicines that affect your immune system. Before you begin treatment with ARCALYST, talk with your healthcare provider about your vaccine history. Ask your healthcare provider whether you should receive any vaccines, including the pneumonia vaccine and flu vaccine, before you begin treatment with ARCALYST. ARCALYST can cause serious side effects: 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 (e.g., rash, swollen face, trouble breathing). Your doctor will do blood tests to check for changes in your blood cholesterol and triglycerides. Common side effects of ARCALYST include injection-site reactions, upper respiratory tract infections, joint and muscle aches, rash, ear infection, sore throat, and runny nose. Tell your doctor if you are scheduled to receive any vaccines, if you are pregnant or plan to become pregnant, and if you are breastfeeding or plan to breastfeed. Tell your doctor if you take other medicines that affect the immune system such as interleukin-1 blockers, tumor necrosis factor blockers, or corticosteroids. For more information about ARCALYST, talk to your doctor and see the Product Information. About Mavrilimumab Mavrilimumab is an investigational fully-human monoclonal antibody that blocks activity of granulocyte macrophage colony stimulating factor (GM-CSF) by specifically binding to the alpha subunit of the GM-CSF receptor. Mavrilimumab was dosed in over 550 patients with rheumatoid arthritis through Phase 2b clinical studies in Europe and achieved prospectively-defined primary endpoints of efficacy and safety. Kiniksa is evaluating mavrilimumab in GCA, and the Phase 2 clinical trial achieved both the primary and secondary efficacy endpoints with statistical significance. Kiniksa continues to evaluate mavrilimumab in COVID-19-related ARDS. The FDA granted Orphan Drug designation to mavrilimumab for the treatment of GCA in 2020. About Vixarelimab Vixarelimab is an investigational fully-human monoclonal antibody that targets oncostatin M receptor beta (OSMRβ), which mediates signaling of interleukin-31 (IL-31) and oncostatin M (OSM), two key cytokines implicated in pruritus, inflammation and fibrosis. Kiniksa believes vixarelimab to be the only monoclonal antibody in development that targets both pathways simultaneously. Kiniksa’s lead indication for vixarelimab is prurigo nodularis, a chronic inflammatory skin condition characterized by severely pruritic skin nodules. The FDA granted Breakthrough Therapy designation to vixarelimab for the treatment of pruritus associated with prurigo nodularis in 2020. About KPL-404 KPL-404 is an investigational humanized monoclonal antibody that is designed to inhibit 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 interaction is an attractive approach for multiple autoimmune disease pathologies. Kiniksa owns or controls the intellectual property related to KPL-404. 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 expectations regarding payers establishing coverage policies for ARCALYST; our beliefs about the future commercial demand for ARCALYST; our beliefs about the timing and results of the final data from the Phase 3 portion of our clinical trial for mavrilimumab in non-mechanically-ventilated patients in the first quarter of 2022; expected timing and design of clinical trials, including (i) the enrollment of patients in and the timing of results from our phase 3 clinical trial of mavrilimumab in COVID-19-related ARDS, (ii) the initiation our Phase 2 proof-of-concept trial of KPL-404 in rheumatoid arthritis by the fourth quarter of 2021, (iii) the enrollment of patients the Phase 2b portion of our clinical trial of vixarelimab in prurigo nodularis and (iv) the potential to evaluate KPL-404 across a range of other autoimmune diseases; our belief that KPL-404 has the potential to address a broad range of autoimmune diseases; our beliefs about the mechanisms of action of our product candidates and potential impact of their approach, including that vixarelimab is the only monoclonal antibody in development that targets both interleukin-31 (IL-31) and oncostatin M (OSM) pathways simultaneously; our belief that all of our product candidates offer the potential for differentiation; our ability to execute on our clinical stage pipeline; our expectations regarding ARCALYST net revenue for the third quarter of 2021; our plans to present at any future medical conferences; and our expectations about our cash reserves funding our current operating plan into 2023. 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; amendments to our clinical trial protocols initiated by us or required by regulatory authorities; delays or difficulty in completing our clinical trials, including as a result of the ongoing COVID-19 pandemic; potential for changes between final data and any preliminary, interim, top-line or other data from clinical trials conducted by us or third parties; our inability to replicate in later clinical trials the positive final data 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 or to delay or deny approval of, or emergency use authorization for, any of our product candidates or to require additional data or trials to support any such approval or authorization; delays, difficulty or 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 products used in our products and product candidates; our reliance on Regeneron as the sole manufacturer of ARCALYST; our reliance on third parties to manufacture our product candidates; 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; the impact of the COVID-19 pandemic and measures taken in response to the pandemic on our business and operations as well as the business and operations of our manufacturers, CROs upon whom we rely on to conduct our clinical trials, and other third parties with whom we conduct business or otherwise engage, including the FDA and other regulatory authorities; changes in our operating plan and funding requirements; and existing or new competition. These and other important factors discussed in our filings with the U.S. Securities and Exchange Commission (the “SEC”), 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. 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 Source: Kiniksa Pharmaceuticals, Ltd.

HAMILTON, Bermuda, April 01, 2021 (GLOBE NEWSWIRE) -- Kiniksa Pharmaceuticals, Ltd. (Nasdaq: KNSA) (Kiniksa), a biopharmaceutical company with a portfolio of assets designed to modulate immunological pathways across a spectrum of diseases, today announced that ARCALYST ® (rilonacept), a weekly, subcutaneously-injected, recombinant fusion protein that blocks interleukin-1 alpha (IL-1α) and interleukin-1 beta (IL-1β) signaling, is now commercially available for recurrent pericarditis. On March 18, 2021, the U.S. Food and Drug Administration (FDA) approved ARCALYST for the treatment of recurrent pericarditis and reduction in risk of recurrence in adults and children 12 years and older. “We are excited to announce that ARCALYST is now available as the first and only approved therapy for patients with recurrent pericarditis,” said Ross Moat, ARCALYST General Manager. “Our experienced commercial and medical affairs teams have already begun to engage with physicians, payers and patients to raise awareness of this innovative treatment option. Kiniksa is committed to patient access and has established Kiniksa One Connect™, our patient support program, which provides comprehensive access and support services for any patient prescribed ARCALYST.” ARCALYST is available through a distribution network comprised of several specialty pharmacies, which provide extensive and timely access across the United States. Kiniksa One Connect™ is available to assist patients on their treatment journey with ARCALYST. The program will help provide potential access, initiation, affordability solutions and ongoing patient support. For more information, call 1-833-KINIKSA (1-833-546-4572). ARCALYST was discovered and developed by Regeneron Pharmaceuticals, Inc. (Regeneron). Upon the approval by the FDA for recurrent pericarditis, Kiniksa took responsibility for sales and distribution of ARCALYST for all the approved indications in the United States, including cryopyrin-associated periodic syndromes (CAPS) and deficiency of IL-1 receptor antagonist (DIRA), and will evenly split profits with Regeneron, as described in the ARCALYST License Agreement. For more information on ARCALYST, visit . About Kiniksa Kiniksa is a biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutic medicines for patients suffering from debilitating diseases with significant unmet medical need. Kiniksa’s portfolio of assets, ARCALYST, mavrilimumab, vixarelimab and KPL-404, are based on strong biologic rationale or validated mechanisms, target underserved conditions and offer the potential for differentiation. These assets are designed to modulate immunological pathways across a spectrum of diseases. For more information, please visit . About Recurrent Pericarditis Recurrent pericarditis is a painful and debilitating autoinflammatory cardiovascular disease that typically presents with chest pain and is often associated with changes in electrical conduction and sometimes buildup of fluid around the heart, called pericardial effusion. Patients who have additional pericarditis episodes following a symptom-free period of 4-6 weeks are identified as having recurrent pericarditis. Recurrent pericarditis symptoms have an impact on quality of life, limit physical activities, and lead to frequent emergency department visits and hospitalizations. Data show that approximately 40,000 patients in the U.S. seek and receive treatment for recurrent pericarditis each year. Of that group, approximately 14,000 patients experience a second or subsequent event (recurrence) due to persistent underlying disease or inadequate response to conventional therapies, such as nonsteroidal anti-inflammatory drugs (NSAIDs), colchicine and corticosteroids. Kiniksa launched the RESONANCE Registry (REgiStry Of the NAtural of recurreNt periCarditis in pEdiatric and adult patients; clinicaltrials.gov: NCT04687358), a voluntary patient registry database led by physician-researchers with experience in managing patients with recurrent pericarditis, in March 2021. This registry aims to capture retrospective and prospective, longitudinal, observational data in up to 500 patients across the U.S. The continued advancement in recurrent pericarditis research underscores Kiniksa’s commitment to partner with the healthcare and patient communities to improve the collective knowledge of this debilitating disease. About ARCALYST ARCALYST is a weekly, subcutaneously-injected recombinant dimeric fusion protein that blocks IL-1α and IL-1β signaling. ARCALYST was discovered by Regeneron and is approved by the FDA for recurrent pericarditis, CAPS, including Familial Cold Autoinflammatory Syndrome and Muckle-Wells Syndrome, and DIRA. The FDA granted Breakthrough Therapy designation to ARCALYST for the treatment of recurrent pericarditis in 2019 and Orphan Drug designation to ARCALYST for the treatment of pericarditis in 2020. About the ARCALYST License Agreement with Regeneron In 2017, Regeneron granted Kiniksa an exclusive license to develop and commercialize ARCALYST worldwide, excluding Israel, Egypt, Turkey and select countries in the Middle East and North Africa. In the United States and Japan, Kiniksa’s license is for all indications other than those involving oncology and local administration to the eye or ear. Upon the approval of the supplemental Biologics License Application (sBLA) for ARCALYST in recurrent pericarditis, the scope of the license granted to Kiniksa expanded to include DIRA and CAPS in the United States and Japan, and Kiniksa assumed the responsibility for sales and distribution of ARCALYST in these additional indications in the United States. Outside the United States and Japan, Kiniksa’s license is for all indications other than CAPS and certain periodic fever syndromes, DIRA, oncology, and local application to the eye or ear. Kiniksa and Regeneron will evenly split profits on sales of ARCALYST after deducting certain commercialization expenses, subject to specified limits. Important information about ARCALYST Injection ARCALYST can 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. You should not begin ARCALYST if you have an infection or have infections that keep coming back. After starting ARCALYST, if you get an infection or show any sign of an infection, including a fever, cough, flu-like symptoms, or have any open sores on your body, call your doctor right away. Treatment with ARCALYST should be stopped if you get a serious 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. Before starting ARCALYST, tell your doctor if you think you have an infection, are being treated for an infection, have signs of an infection, have any open sores, have a history of infections that keep coming back, have asthma, have diabetes or an immune system problem, have tuberculosis, or have been in contact with someone who has had tuberculosis, has or has had HIV, hepatitis B or hepatitis C, or takes other medicines that affect your immune system. Before you begin treatment with ARCALYST, talk with your healthcare provider about your vaccine history. Ask your healthcare provider whether you should receive any vaccines, including the pneumonia vaccine and flu vaccine, before you begin treatment with ARCALYST. ARCALYST can cause serious side effects: 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 (e.g., rash, swollen face, trouble breathing). Your doctor will do blood tests to check for changes in your blood cholesterol and triglycerides. Common side effects of ARCALYST include injection-site reactions, upper respiratory tract infections, joint and muscle aches, rash, ear infection, sore throat, and runny nose. Tell your doctor if you are scheduled to receive any vaccines, if you are pregnant or plan to become pregnant, and if you are breastfeeding or plan to breastfeed. Tell your doctor if you take other medicines that affect the immune system such as interleukin-1 blockers, tumor necrosis factor blockers, or corticosteroids. For more information about ARCALYST, talk to your doctor and see the Product Information. 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 belief about the continued availability of ARCALYST; our targeted patient population; the potential impact of the Kiniksa One Connect program to help provide access, initiation and affordability solutions as well as ongoing support for any patient receiving ARCALYST therapy; and our beliefs about the mechanisms of action of our product candidates and potential impact of their approach. 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: the potential inability of our Kiniksa One Connect program to effectively help provide access, initiation, affordability solutions and ongoing support for any patient receiving ARCALYST therapy; the potential for ARCALYST to not gain market acceptance by physicians, patients, or third-party payers for the treatment of recurrent pericarditis; the potential delay or failure of ARCALYST to obtain or maintain coverage and adequate reimbursement for the treatment of recurrent pericarditis; the incidence and prevalence of our target patient population for ARCALYST in recurrent pericarditis may be smaller than we estimate; potential undesirable side effects caused by ARCALYST; our reliance on Regeneron as the sole source of supply of the drug substance and drug products used in ARCALYST and to manufacture our clinical and commercial supply of ARCALYST; drug substance and/or drug product shortages; the impact of the COVID-19 pandemic and measures taken in response to the pandemic on our business and operations as well as the business and operations of our manufacturers, including Regeneron, and other third parties with whom we conduct business or otherwise engage, including regulatory authorities; changes in our operating plan and funding requirements; and existing or new competition. These and other important factors discussed under the caption “Risk Factors” in our Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on February 25, 2021 and our other reports subsequently filed with the SEC 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. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. 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. ENBREL, HUMIRA, KINERET, and REMICADE are trademarks of Immunex Corporation, AbbVie Biotechnology Ltd., Sobi, Inc., and Janssen Biotech, Inc., respectively. Every Second Counts!™ Kiniksa Investor and Media Contact Mark Ragosa (781) 430-8289 mragosa@kiniksa.com