Dermatomyositis

Retrospective analysis suggests Acthar Gel treatment was associated with similar improvement in health status and overall symptom reduction in African Americans and non-African Americans with symptomatic sarcoidosis1 Findings on treatment response and physician-reported outcomes indicate that Acthar Gel may be a viable treatment option for both African American and non-African American sarcoidosis patients1 DUBLIN, March 11, 2024 /PRNewswire/ -- Mallinckrodt plc, a global specialty pharmaceutical company, today announced the publication of findings from a retrospective chart review of Acthar® Gel (repository corticotropin injection) treatment outcomes for African American and non-African American patients with symptomatic sarcoidosis – including treatment patterns, co-medication use, and overall health outcomes.1 This analysis suggested that Acthar Gel treatment was associated with similar improvements in health outcomes, a reduction in symptoms, and reduced co-medication use in both African Americans and non-African Americans with symptomatic sarcoidosis.1 The manuscript was recently published online in Therapeutics & Clinical Risk Management. This research builds upon findings from a study investigating the clinical and real-world outcomes of Acthar Gel treatment in a subgroup of African Americans with symptomatic sarcoidosis, previously presented at the 2022 American Thoracic Society Annual International Conference in San Francisco, CA, and published in Therapeutic Advances in Respiratory Disease in 2019.2 Acthar is a naturally sourced complex mixture of adrenocorticotropic hormone analogs and other pituitary peptides.3 Acthar Gel is approved by the U.S. Food and Drug Administration (FDA) for the treatment of several autoimmune disorders and medical conditions known to cause inflammation, including symptomatic sarcoidosis.3 Please see additional indications and Important Safety Information below. "The results of this retrospective medical chart review highlight unmet needs that exist for African American patients with symptomatic sarcoidosis, who are disproportionately affected by the disease, and reinforce Acthar Gel's potential to help improve health outcomes for appropriate patients,"1,4,5 said George Wan, Ph.D., M.P.H., Vice President, Evidence Generation and Data Sciences, Mallinckrodt. "This research reflects Mallinckrodt's commitment to collecting real-world data on the relationship between patient characteristics, treatment patterns, and outcomes to support clinicians' treatment decisions and address disparities in symptomatic sarcoidosis care."1 About the Study:1 In this retrospective analysis, a national database of Acthar Gel prescribers and the American Medical Association Physician Master were merged to obtain a sample of 98 physicians to provide data on the last 6 consecutive patients seen who met the study's eligibility criteria. The medical records were extracted for adult patients (≥18 years) with a diagnosis of advanced symptomatic sarcoidosis, who had ≥1 symptom, and who had either completed at least one course of Acthar Gel or had received Acthar Gel for at least 6 months during data collection. A total of 272 patients with symptomatic sarcoidosis were included in this analysis (African American (AA): n=168; non-African American (non-AA): n=104). Most patients in both race groups were diagnosed with stage 3 or 4 sarcoidosis based on chest imaging and biopsy (AA: 61.3%, n=103 vs. non-AA: 68.3%, n=71; p=0.2453). Per an assessment of patient characteristics and Acthar Gel treatment patterns, this analysis suggests that the average time since the first diagnosis of sarcoidosis was slightly longer among AA than non-AA (mean ± SD: 5.2 ± 7.6 years vs. 4.3 ± 5.1 years; p>0.05).1 Further, a lower proportion of AA vs. non-AA had completed a course of Acthar Gel therapy (44%, n=74 vs. 55.8%, n=58; p=0.0602) during the data collection period,1 and the duration of Acthar Gel treatment was slightly longer among AA vs. non-AA (mean ± SD: 31.7 ± 32 vs. 29 ± 27.4 weeks; p>0.05).1 "This research underscores the importance of conducting real-world studies to provide data that helps to recognize the disparities in symptomatic sarcoidosis care and address unmet needs to better support health outcomes for all appropriate patients," said Mary McGowan, Chief Executive Officer, Foundation for Sarcoidosis Research (FSR). FSR is the leading international organization dedicated to finding a cure for sarcoidosis and improving care for sarcoidosis patients through research, education, and support. Key Findings: Co-Medication Utilization Patterns1 Significantly fewer patients among both race groups were on any co-medication after Acthar Gel initiation (p<0.0001): AA before: 88.1%, n=148 vs. after: 20.2%, n=34 Non-AA before: 83.7%, n=87 vs. after: 24%, n=25 More AA had a reduction in any co-medication use after Acthar Gel initiation (AA: -77% vs. non-AA: -71%; p<0.0001). After Acthar Gel initiation, fewer AA (before: 59.5%, n=100 vs. after: 11.9%, n=20; p<0.0001) and non-AA (before: 65.4%, n=68 vs. after: 14.4%, n=15; p<0.0001) were on glucocorticoids. Overall, the mean prednisone dose reduced after Acthar Gel initiation among AA (before: 18.5 mg/day vs. after: 10.1 mg/day) and non-AA (before: 17.6 mg/day vs. after: 10 mg/day). The proportion of patients on prednisone daily dose of <10 mg increased after Acthar Gel initiation among both race groups (AA before: 27.8%, n=27/97 vs. after: 31.6%, n=6/19; non-AA before: 13.6%, n=9/66 vs. after: 60%, n=9/15). Physicians' Assessment of Improvement1 The health status of 95.2% (n=160) of AA and 97.1% (n=101) of non-AA improved following treatment with Acthar Gel, based on physician-provided assessments of patient outcomes. Treatment response to overall symptoms was not statistically significantly different between both race groups (AA: 72.6%, n=122 vs. non-AA: 70.2%, n=73) The most frequently reported changes in symptoms following Acthar Gel treatment in both race groups were: Reduction in inflammation (AA: 33.9%, n=57 vs. non-AA: 32.7%, n=34) Improvement in quality of life (AA: 31.5%, n=53 vs. non-AA: 34.6%, n=36) Improvement in lung function (AA: 30.4%, n=51 vs. non-AA: 53.8%, n=56; p<0.05) Reduction in fatigue (AA: 27.4%, n=46 vs. non-AA: 35.6%, n=37) Limitations:1 Data retrospectively collected from medical charts of patients may have omissions and errors. Completeness of information was assessed to the extent possible to minimize bias resulting from any missing data. In addition, only data available in medical charts or known to be complete to the respondents were extracted. Additional limitations of this study include: Physicians' standards for the interpretation of change in each patient's health status vary which may result in bias due to over- or under-estimation of the effectiveness of Acthar Gel. This study was unable to quantify clinical data such as diagnostic and safety measures, clinical and sustained response after treatment, and reasons for discontinuation or dose adjustments related to Acthar Gel. Due to the exploratory nature of this analysis, data were not collected for other medications besides Acthar Gel. Data on adverse reactions in this population, drivers of the decision to use Acthar Gel, and detailed information on prior therapies were not captured. This study was sponsored by Mallinckrodt Pharmaceuticals. INDICATIONS Acthar Gel is indicated for: Inducing a diuresis or a remission of proteinuria in nephrotic syndrome without uremia of the idiopathic type or that due to lupus erythematosus Monotherapy for the treatment of infantile spasms in infants and children under 2 years of age Treatment of acute exacerbations of multiple sclerosis in adults. Controlled clinical trials have shown Acthar to be effective in speeding the resolution of acute exacerbations of multiple sclerosis. However, there is no evidence that it affects the ultimate outcome or natural history of the disease Severe acute and chronic allergic and inflammatory processes involving the eye and its adnexa such as: keratitis, iritis, iridocyclitis, diffuse posterior uveitis and choroiditis, optic neuritis, chorioretinitis, anterior segment inflammation Symptomatic sarcoidosis Treatment during an exacerbation or as maintenance therapy in selected cases of systemic lupus erythematosus Treatment during an exacerbation or as maintenance therapy in selected cases of dermatomyositis (polymyositis) Adjunctive therapy for short-term administration (to tide the patient over an acute episode or exacerbation) in: psoriatic arthritis; rheumatoid arthritis, including juvenile rheumatoid arthritis (selected cases may require low-dose maintenance therapy); ankylosing spondylitis IMPORTANT SAFETY INFORMATION Contraindications Acthar is contraindicated: For intravenous administration In infants under 2 years of age who have suspected congenital infections With concomitant administration of live or live attenuated vaccines in patients receiving immunosuppressive doses of Acthar In patients with scleroderma, osteoporosis, systemic fungal infections, ocular herpes simplex, recent surgery, history of the presence of a peptic ulcer, congestive heart failure, uncontrolled hypertension, primary adrenocortical insufficiency, adrenocortical hyperfunction, or sensitivity to proteins of porcine origin Warnings and Precautions The adverse effects of Acthar are related primarily to its steroidogenic effects Acthar may increase susceptibility to new infection or reactivation of latent infections Suppression of the hypothalamic-pituitary-adrenal (HPA) axis may occur following prolonged therapy with the potential for adrenal insufficiency after withdrawal of the medication. Adrenal insufficiency may be minimized by tapering of the dose when discontinuing treatment. During recovery of the adrenal gland patients should be protected from the stress (e.g., trauma or surgery) by the use of corticosteroids. Monitor patients for effects of HPA axis suppression after stopping treatment Cushing's syndrome may occur during therapy but generally resolves after therapy is stopped. Monitor patients for signs and symptoms Acthar can cause elevation of blood pressure, salt and water retention, and hypokalemia. Monitor blood pressure and sodium and potassium levels Acthar often acts by masking symptoms of other diseases/disorders. Monitor patients carefully during and for a period following discontinuation of therapy Acthar can cause gastrointestinal (GI) bleeding and gastric ulcer. There is also an increased risk for perforation in patients with certain GI disorders. Monitor for signs of perforation and bleeding Acthar may be associated with central nervous system effects ranging from euphoria, insomnia, irritability, mood swings, personality changes, and severe depression to psychosis. Existing conditions may be aggravated Patients with comorbid disease may have that disease worsened. Caution should be used when prescribing Acthar in patients with diabetes and myasthenia gravis Prolonged use of Acthar may produce cataracts, glaucoma, and secondary ocular infections. Monitor for signs and symptoms Acthar is immunogenic and prolonged administration of Acthar may increase the risk of hypersensitivity reactions. Cases of anaphylaxis have been reported in the postmarketing setting. Neutralizing antibodies with chronic administration may lead to loss of endogenous ACTH and Acthar activity There may be an enhanced effect in patients with hypothyroidism and in those with cirrhosis of the liver Long-term use may have negative effects on growth and physical development in children. Monitor pediatric patients Decrease in bone density may occur. Bone density should be monitored in patients on long-term therapy Adverse Reactions Commonly reported postmarketing adverse reactions for Acthar include injection site reaction, asthenic conditions (including fatigue, malaise, asthenia, and lethargy), fluid retention (including peripheral swelling), insomnia, headache, and blood glucose increased The most common adverse reactions for the treatment of infantile spasms (IS) are increased risk of infections, convulsions, hypertension, irritability, and pyrexia. Some patients with IS progress to other forms of seizures; IS sometimes masks these seizures, which may become visible once the clinical spasms from IS resolve Pregnancy Acthar may cause fetal harm when administered to a pregnant woman Please see full Prescribing Information for additional Important Safety Information. ABOUT SYMPTOMATIC SARCOIDOSIS Sarcoidosis is a challenging and rare multisystem disease.6 In some cases, the symptoms may come and go throughout a lifetime.6 This is referred to as symptomatic sarcoidosis.6 In people with sarcoidosis, the immune system overreacts, forming clumps of cells called granulomas that result in inflammation to the body's tissues.7 The disease can impact any organ, but it most often impacts the lungs, lymph nodes, eyes, liver, and skin.8 Nearly 90 percent of people with sarcoidosis will suffer lung problems.8 Concomitant involvement of organs outside of the lungs is common, occurring in more than half of all sarcoidosis cases, according to one study.2 ABOUT MALLINCKRODT Mallinckrodt is a global business consisting of multiple wholly owned subsidiaries that develop, manufacture, market and distribute specialty pharmaceutical products and therapies. The company's Specialty Brands reportable segment's areas of focus include autoimmune and rare diseases in specialty areas like neurology, rheumatology, hepatology, nephrology, pulmonology, ophthalmology, and oncology; immunotherapy and neonatal respiratory critical care therapies; analgesics; and gastrointestinal products. Its Specialty Generics reportable segment includes specialty generic drugs and active pharmaceutical ingredients. To learn more about Mallinckrodt, visit CAUTIONARY STATEMENTS RELATED TO FORWARD-LOOKING STATEMENTS This release contains forward-looking statements, including with regard to Acthar® Gel, its potential to improve health and treatment outcomes, its potential impact on patients. The statements are based on assumptions about many important factors, including the following, which could cause actual results to differ materially from those in the forward-looking statements: the effects of Mallinckrodt's recent emergence from bankruptcy; satisfaction of, and compliance with, regulatory and other requirements; actions of regulatory bodies and other governmental authorities; changes in laws and regulations; issues with product quality, manufacturing or supply, or patient safety issues or adverse side effects or adverse reactions associated with Acthar Gel; and other risks identified and described in more detail in the "Risk Factors" section of Mallinckrodt's most recent Annual Report on Form 10-K and other filings with the SEC, all of which are available on its website. The forward-looking statements made herein speak only as of the date hereof and Mallinckrodt does not assume any obligation to update or revise any forward-looking statement, whether as a result of new information, future events and developments or otherwise, except as required by law. CONTACT Media Inquiries Green Room Communications 908-577-4531 mediainquiries@grcomms.com Investor Relations Derek Belz Vice President, Investor Relations 314-654-3950 derek.belz@mnk.com Mallinckrodt, the "M" brand mark and the Mallinckrodt Pharmaceuticals logo are trademarks of a Mallinckrodt company. Other brands are trademarks of a Mallinckrodt company or their respective owners. ©2024 Mallinckrodt. US-2400042 03/24 References ___________________________________ 1 Bindra J, et al. Acthar Gel in African Americans versus Non-African Americans with Symptomatic Sarcoidosis: Physician Assessment of Patient Medical Records. Ther Clin Risk Manag. 2024;20:83-94 . 2Chopra I, et al. Repository Corticotropin Injection in Patients with Advanced Symptomatic Sarcoidosis: Retrospective Analysis of Medical Records. Ther Adv Res Dis. 2019(13);1-11. DOI: 10.1177/1753466619888127. 3 Acthar® Gel (repository corticotropin injection) [prescribing information]. Mallinckrodt ARD LLC. 2023. 4 Judson MA. Pulmonary Sarcoidosis: A Guide for the Practicing Clinician. Humana Press, New York, NY. 2014. 8;149-186. 5 Hena, K. M. Sarcoidosis Epidemiology: Race Matters. Front Immunol. 2020;11:1-5. 6 Sarcoidosis. American College of Chest Physicians. Available at: . Accessed February 2024. 7 Sarcoidosis Overview. 2019. Cleveland Clinic. Available at: . Accessed February 2024. 8 Judson MA, Boan AD, Lackland DT. The Clinical Course of Sarcoidosis: Presentation, Diagnosis, and Treatment in a Large White and Black Cohort in the United States. Sarcoidosis Vasc Diffuse Lung Dis. 2012. 29(2);119-127. View original content to download multimedia: SOURCE Mallinckrodt plc Company Codes: NYSE:MNK, OTC-BB:MCKPF, OTC-BB:MNKPF, OTC-PINK:MCKPF

– Acthar Gel Single-Dose Pre-filled SelfJect Injector is a self-controlled, pre-filled delivery device1 for appropriate patients with a range of chronic and acute inflammatory and autoimmune conditions2 – – This first-in-class delivery device reduces the steps required for patients and caregivers to administer Acthar Gel treatment1 and underscores Mallinckrodt's mission by advancing Acthar Gel therapeutic modernization efforts to address patient needs – – Acthar Gel Single-Dose Pre-filled SelfJect Injector is expected to launch in the U.S. in the second half of 2024 – DUBLIN, March 1, 2024 /PRNewswire/ -- Mallinckrodt plc, a global specialty pharmaceutical company, today announced that the U.S. Food and Drug Administration (FDA) has approved Mallinckrodt's supplemental New Drug Application (sNDA) for the Acthar® Gel (repository corticotropin injection) Single-Dose Pre-filled SelfJect™ Injector (herein referred to as "SelfJect"), a new delivery device for Acthar Gel for appropriate patients with a range of chronic and acute inflammatory and autoimmune conditions.2 SelfJect is intended to provide the appropriate subcutaneous dose of Acthar Gel, as prescribed by a healthcare professional, and is designed to help give patients control of their administration.1,3 Acthar Gel is a naturally sourced complex mixture of adrenocorticotropic hormone analogs and other pituitary peptides.2 Acthar Gel is approved by the U.S. FDA for the treatment of several autoimmune disorders and medical conditions known to cause inflammation.2 Please see Indications and Important Safety Information for Acthar Gel below. "We're excited to bring this innovation to U.S. patients with chronic and acute inflammatory and autoimmune conditions. This approval reflects Mallinckrodt's longstanding commitment to clinical research and therapeutic modernization efforts providing a new delivery device for patients, caregivers, and medical professionals managing these challenging conditions," said Peter Richardson, MRCP (UK), Executive Vice President and Chief Scientific Officer. With this approval, Acthar Gel is the first in its class of medications to offer a self-controlled, pre-filled delivery device for appropriate patients with a range of chronic and acute inflammatory and autoimmune conditions.1,2 SelfJect may allow patients to self-administer Acthar Gel with fewer steps, as prescribed by a healthcare professional.1 The delivery device is pre-filled with the prescribed dose of Acthar Gel in 40-unit or 80-unit versions,1 is designed to help patients with dexterity issues,4 and has additional safety features including a hidden needle to help protect patients against needlestick injury.3 Acthar Gel has an established efficacy and safety profile, as well as a long track record of clinical experience spanning more than 70 years.2 Acthar Gel has been prescribed by over 9,200 healthcare professionals and used by more than 43,500 patients.5 Mallinckrodt is committed to providing therapy for appropriate patients with difficult-to-treat conditions. Mallinckrodt offers a suite of services for eligible Acthar Gel patients including support with insurance coverage, commercial copay assistance, a patient assistance program, injection training services, and customized assistance by a nurse navigator. Mallinckrodt also offers a team of field-based experts who provide education for healthcare professionals on the reimbursement process as well as tools available for patients. For more information about Mallinckrodt's programs and patient support please visit ActharHCP.com. SelfJect is expected to launch in the U.S. in the second half of 2024. Acthar Gel will continue to be available as an injection with a vial and syringe. INDICATIONS Acthar Gel is indicated for: Inducing a diuresis or a remission of proteinuria in nephrotic syndrome without uremia of the idiopathic type or that due to lupus erythematosus Monotherapy for the treatment of infantile spasms in infants and children under 2 years of age Treatment of acute exacerbations of multiple sclerosis in adults. Controlled clinical trials have shown Acthar to be effective in speeding the resolution of acute exacerbations of multiple sclerosis. However, there is no evidence that it affects the ultimate outcome or natural history of the disease Severe acute and chronic allergic and inflammatory processes involving the eye and its adnexa such as: keratitis, iritis, iridocyclitis, diffuse posterior uveitis and choroiditis, optic neuritis, chorioretinitis, anterior segment inflammation Symptomatic sarcoidosis Treatment during an exacerbation or as maintenance therapy in selected cases of systemic lupus erythematosus Treatment during an exacerbation or as maintenance therapy in selected cases of dermatomyositis (polymyositis) Adjunctive therapy for short-term administration (to tide the patient over an acute episode or exacerbation) in: psoriatic arthritis; rheumatoid arthritis, including juvenile rheumatoid arthritis (selected cases may require low-dose maintenance therapy); ankylosing spondylitis IMPORTANT SAFETY INFORMATION Contraindications Acthar is contraindicated: For intravenous administration In infants under 2 years of age who have suspected congenital infections With concomitant administration of live or live attenuated vaccines in patients receiving immunosuppressive doses of Acthar In patients with scleroderma, osteoporosis, systemic fungal infections, ocular herpes simplex, recent surgery, history of the presence of a peptic ulcer, congestive heart failure, uncontrolled hypertension, primary adrenocortical insufficiency, adrenocortical hyperfunction, or sensitivity to proteins of porcine origin Warnings and Precautions The adverse effects of Acthar are related primarily to its steroidogenic effects Acthar may increase susceptibility to new infection or reactivation of latent infections Suppression of the hypothalamic-pituitary-adrenal (HPA) axis may occur following prolonged therapy with the potential for adrenal insufficiency after withdrawal of the medication. Adrenal insufficiency may be minimized by tapering of the dose when discontinuing treatment. During recovery of the adrenal gland patients should be protected from the stress (e.g., trauma or surgery) by the use of corticosteroids. Monitor patients for effects of HPA axis suppression after stopping treatment Cushing's syndrome may occur during therapy but generally resolves after therapy is stopped. Monitor patients for signs and symptoms Acthar can cause elevation of blood pressure, salt and water retention, and hypokalemia. Monitor blood pressure and sodium and potassium levels Acthar often acts by masking symptoms of other diseases/disorders. Monitor patients carefully during and for a period following discontinuation of therapy Acthar can cause gastrointestinal (GI) bleeding and gastric ulcer. There is also an increased risk for perforation in patients with certain GI disorders. Monitor for signs of perforation and bleeding Acthar may be associated with central nervous system effects ranging from euphoria, insomnia, irritability, mood swings, personality changes, and severe depression to psychosis. Existing conditions may be aggravated Patients with comorbid disease may have that disease worsened. Caution should be used when prescribing Acthar in patients with diabetes and myasthenia gravis Prolonged use of Acthar may produce cataracts, glaucoma, and secondary ocular infections. Monitor for signs and symptoms Acthar is immunogenic and prolonged administration of Acthar may increase the risk of hypersensitivity reactions. Cases of anaphylaxis have been reported in the postmarketing setting. Neutralizing antibodies with chronic administration may lead to loss of endogenous ACTH and Acthar activity There may be an enhanced effect in patients with hypothyroidism and in those with cirrhosis of the liver Long-term use may have negative effects on growth and physical development in children. Monitor pediatric patients Decrease in bone density may occur. Bone density should be monitored in patients on long-term therapy Adverse Reactions Commonly reported postmarketing adverse reactions for Acthar include injection site reaction, asthenic conditions (including fatigue, malaise, asthenia, and lethargy), fluid retention (including peripheral swelling), insomnia, headache, and blood glucose increased The most common adverse reactions for the treatment of infantile spasms (IS) are increased risk of infections, convulsions, hypertension, irritability, and pyrexia. Some patients with IS progress to other forms of seizures; IS sometimes masks theses seizures, which may become visible once the clinical spasms from IS resolve Pregnancy Acthar may cause fetal harm when administered to a pregnant woman Please see full Prescribing Information for additional Important Safety Information. ABOUT MALLINCKRODT Mallinckrodt is a global business consisting of multiple wholly owned subsidiaries that develop, manufacture, market and distribute specialty pharmaceutical products and therapies. The company's Specialty Brands reportable segment's areas of focus include autoimmune and rare diseases in specialty areas like neurology, rheumatology, hepatology, nephrology, pulmonology, ophthalmology, and oncology; immunotherapy and neonatal respiratory critical care therapies; analgesics; and gastrointestinal products. Its Specialty Generics reportable segment includes specialty generic drugs and active pharmaceutical ingredients. To learn more about Mallinckrodt, visit . CAUTIONARY STATEMENTS RELATED TO FORWARD-LOOKING STATEMENTS This release contains forward-looking statements, including with regard to Acthar® Gel, the Acthar® Gel (repository corticotropin injection) Single-Dose Pre-filled SelfJect™ Injector, the potential of these products to improve health and treatment outcomes, their potential impact on patients and the availability of Acthar Gel Single-Dose Pre-filled SelfJect Injector in the U.S. in the future. The statements are based on assumptions about many important factors, including the following, which could cause actual results to differ materially from those in the forward-looking statements: the effects of Mallinckrodt's recent emergence from bankruptcy; satisfaction of, and compliance with, regulatory and other requirements; actions of regulatory bodies and other governmental authorities; changes in laws and regulations; changes in market demand; issues with product quality, manufacturing or supply, or patient safety issues or adverse side effects or adverse reactions associated with Acthar Gel and Acthar Gel Single-Dose Pre-filled SelfJect Injector; and other risks identified and described in more detail in the "Risk Factors" section of Mallinckrodt's most recent Annual Report on Form 10-K and other filings with the SEC, all of which are available on its website. The forward-looking statements made herein speak only as of the date hereof and Mallinckrodt does not assume any obligation to update or revise any forward-looking statement, whether as a result of new information, future events and developments or otherwise, except as required by law. CONTACT Media Inquiries Green Room Communications 908-577-4531 [email protected] Investor Relations Derek Belz Vice President, Investor Relations 314-654-3950 [email protected] Mallinckrodt, the "M" brand mark and the Mallinckrodt Pharmaceuticals logo are trademarks of a Mallinckrodt company. Other brands are trademarks of a Mallinckrodt company or their respective owners. ©2024 Mallinckrodt. US-2300898 02/24 References 1 Data on file – ref-05469. Mallinckrodt Pharmaceuticals, Inc. 2 Acthar® Gel (repository corticotropin injection) [prescribing information]. Mallinckrodt ARD LLC. 2024. 3 Data on file – ref-05573. Mallinckrodt Pharmaceuticals, Inc. 4 Data on file – ref-05468. Mallinckrodt Pharmaceuticals, Inc. 5 Data on file – ref-05336. Mallinckrodt Pharmaceuticals, Inc. SOURCE Mallinckrodt plc

$374 million in fourth quarter and $1.2 billion in full year global net product sales sBLA for VYVGART® Hytrulo for CIDP accepted for priority review by FDA with PDUFA target action date of June 21, 2024 On track to report data from six Phase 2 proof-of-concept trials by end of 2024 Management to host conference call today at 2:30 pm CET (8:30 am ET) February 29, 2024, 7:00 am CET Amsterdam, the Netherlands – argenx SE (Euronext & Nasdaq: ARGX), a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases, today reported financial results for the full year 2023 and provided a fourth quarter business update. “argenx reached thousands of new patients and their families in 2023 by delivering on our commitment to make VYVGART available to the global MG community,” said Tim Van Hauwermeiren, Chief Executive Officer of argenx. “This expansion demonstrates that VYVGART has the potential to address the high unmet need for innovation in patients suffering from MG, and moves us closer to sustainability as we build an integrated immunology company. Clinically, we generated significant data through multiple study readouts, achieving key milestones for both the CIDP and MMN patient communities and importantly advancing our second molecule, empasiprubart. Looking forward to 2024, we will act with a continued sense of purpose to expand our patient reach. We will use the learnings and momentum from our gMG launch to strategically lay the groundwork for a potential CIDP approval, leveraging our current infrastructure and deep relationships in the neurology community to position VYVGART SC for success. CIDP patients have been waiting for innovation, and we are eager to translate the transformative ADHERE data into potential benefit for patients as quickly as possible.” FOURTH QUARTER 2023 AND RECENT BUSINESS UPDATE Reaching More Patients with VYVGART VYVGART® (efgartigimod alfa-fcab) is a first-in-class antibody fragment targeting the neonatal Fc receptor (FcRn), and is now approved in more than 30 countries globally for the treatment of generalized myasthenia gravis (gMG). VYVGART subcutaneous (SC) (efgartigimod alfa and hyaluronidase-qvfc) is approved in the U.S. (as VYVGART Hytrulo), Japan (as VYVDURA®) and Europe, making VYVGART the only gMG treatment available as both an IV and simple SC injection. argenx is planning to reach more patients commercially through its multi-dimensional expansion efforts, including patients earlier in the MG treatment paradigm and new patient populations through global regulatory approvals for MG and the expansion of use to treat additional autoimmune indications. Generated global net product revenues (inclusive of both VYVGART and VYVGART SC) of $374 million in the fourth quarter and $1.2 billion in the full year of 2023Medicines and Healthcare products Regulatory Agency (MHRA) approved VYVGART SC in the United Kingdom for the treatment of adult patients with gMG on February 6, 2024, with self-administrationMinistry of Health, Labour and Welfare (MHLW) approved VYVDURA in Japan for the treatment of adult patients with gMG, inclusive of seronegative patients, on January 18, 2024, with self-administrationDecisions on regulatory approvals of VYVGART for gMG expected in Switzerland, Australia, Saudi Arabia and South Korea by end of 2024Decision on approval of VYVGART SC for gMG in China through Zai Lab expected by end of 2024Decision on approval of VYVGART for primary immune thrombocytopenia (ITP) in Japan expected in first quarter of 2024Supplemental Biologics License Application (sBLA) for VYVGART Hytrulo accepted for priority review by FDA for chronic inflammatory demyelinating polyneuropathy (CIDP); Prescription Drug User Fee Act (PDUFA) target action date of June 21, 2024Regulatory submissions of VYVGART SC for CIDP in Japan, Europe, China and Canada expected in 2024Registrational studies to expand VYVGART label into broader MG populations, including in seronegative patients, expected to start in 2024Update on pre-filled syringe development expected in first half of 2024; ongoing clinical studies expected to support potential approval in gMG and CIDP in 2024 Advancing Current Pipeline argenx continues to demonstrate breadth and depth within its immunology pipeline and is advancing multiple pipeline-in-a-product candidates. With efgartigimod, argenx is solidifying its leadership in FcRn and is on track to be approved or in development in 15 autoimmune indications by 2025. Beyond efgartigimod, argenx is advancing its earlier stage pipeline programs, including empasiprubart (C2 inhibitor) with Phase 2 studies ongoing in multifocal motor neuropathy (MMN), delayed graft function (DGF) and dermatomyositis (DM). In addition, argenx is evaluating ARGX-119, a muscle-specific kinase (MuSK) agonist in both congenital myasthenic syndrome (CMS) and amyotrophic lateral sclerosis (ALS). Evaluation ongoing to determine path forward in BALLAD study evaluating efgartigimod in bullous pemphigoid (BP), with an update expected in 2024Topline data from Phase 2 RHO study evaluating efgartigimod in primary Sjogren’s syndrome expected in first half of 2024Topline data from Phase 2 ALPHA study evaluating efgartigimod in post-COVID-19 postural orthostatic tachycardia syndrome (PC-POTS) expected in first half of 2024Topline data from seamless Phase 2/3 ALKIVIA study evaluating efgartigimod across three myositis subsets (immune-mediated necrotizing myopathy (IMNM), anti-synthetase syndrome (ASyS), and DM) expected in second half of 2024Full Phase 2 topline data from ARDA study evaluating empasiprubart in MMN expected to be shared in 2024; cohort 2 is ongoing to determine dose response ahead of Phase 3 study startPhase 1 study of ARGX-119 ongoing in healthy volunteers; subsequent Phase 1b/2a trials planned to assess early signal detection in patients with CMS and ALS in 2024 Leveraging Repeatable Innovation Playbook to Drive Long-Term Pipeline Growth argenx continues to invest in its discovery engine, the Immunology Innovation Program (IIP), to drive long-term sustainable pipeline growth. Through the IIP, four new pipeline candidates have been nominated, including: ARGX-213 targeting FcRn and further solidifying argenx’s leadership in this new class of medicine; ARGX-121 and ARGX-220, which are first-in-class targets broadening argenx’s focus across the immune system; and ARGX-109, targeting IL-6, which plays an important role in inflammation. On track to file four investigational new drug (IND) applications by end of 2025Received $30M milestone from AbbVie for advancement of ABBV-151 (ARGX-115) to Phase 2 FOURTH QUARTER AND FULL YEAR 2023 FINANCIAL RESULTS argenx SE UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF PROFIT OR LOSS Three Months Ended December 31, Twelve Months Ended December 31, (in thousands of $ except for shares and EPS) 2023 2022 2023 2022Product net sales $374,351 $173,396 $1,190,783 $400,720Collaboration revenue 32,486 764 35,533 10,026Other operating income 11,003 7,956 42,278 34,520Total operating income $417,840 $182,116 $1,268,594 $445,267 Cost of sales $(39,477) $(12,786) $(117,835) $(29,431)Research and development expenses (306,373) (147,798) (859,492) (663,366)Selling, general and administrative expenses (208,826) (135,287) (711,905) (472,132)Loss from investment in joint venture (1,788) (677) (4,411) (677)Total operating expenses (556,464) (296,548) (1,693,643) (1,165,607) Operating loss $(138,624) $(114,432) $(425,049) $(720,341) Financial income $40,308 $13,925 $107,386 $27,665Financial expense (280) (990) (906) (3,906)Exchange gains/(losses) 37,418 60,259 14,073 (32,732) Loss for the period before taxes $(61,178) $(41,238) $(304,496) $(729,314)Income tax benefit / (expense) $(37,994) $2,625 $9,443 $19,720Loss for the period $(99,172) $(38,613) $(295,053) $(709,594)Loss for the year attributable to: Owners of the parent $(99,172) $(38,613) $(295,053) $(709,594)Weighted average number of shares outstanding 59,118,827 55,364,124 57,169,253 54,381,371Basis and diluted (loss) per share (in $) (1.68) (0.70) (5.16) (13.05)Net increase/(decrease) in cash, cash equivalents and current financial assets compared to year-end 2022 and 2021 $987,296 $(144,180)Cash and cash equivalents and current financial assets at the end of the period $3,179,844 $2,192,548 DETAILS OF THE FINANCIAL RESULTS Total operating income for the fourth quarter and full year in 2023 was $418 million and $1,269 million, respectively, compared to $182 million and $445 million for the same periods in 2022, and mainly consists of: Product net sales of VYVGART and VYVGART SC for the fourth quarter and full year in 2023, were $374 million and $1,191 million, respectively, compared to $173 million and $401 million for the same periods in 2022.Collaboration revenue for the fourth quarter and full year in 2023 was $32 million and $36 million, respectively, compared to $1 million and $10 million for the same periods in 2022. The increase is mainly related to the clinical development milestone argenx achieved with AbbVie following the dosing of the first patient in the Phase 2 trial for ABBV-151. Collaboration revenue for full year in 2023 also includes $1 million in royalty revenue from VYVGART sales in China.Other operating income for the fourth quarter and full year in 2023 was $11 million and $42 million, respectively, compared to $8 million and $35 million for the same periods in 2022. The other operating income for the fourth quarter and full year in 2023, primarily relates to research and development tax incentives and payroll tax rebates. Total operating expenses for the fourth quarter and full year in 2023 were $556 million and $1,694 million, respectively, compared to $297 million and $1,166 million for the same periods in 2022, and mainly consists of: Cost of sales for the fourth quarter and full year in 2023 was $39 million and $118 million, respectively, compared to $13 million and $29 million for the same periods in 2022. The cost of sales was recognized with respect to the sale of VYVGART and VYVGART SC.Research and development expenses for the fourth quarter and full year in 2023 were $306 million and $859 million, respectively, compared to $148 million and $663 million for the same periods in 2022. The research and development expenses mainly relate to external research and development expenses and personnel expenses incurred in the clinical development of efgartigimod in various indications and the expansion of other clinical and preclinical pipeline candidates. The research and development expenses for the fourth quarter and the full year in 2023, includes the amortization of the priority review voucher submitted with the sBLA filling for VYVGART Hytrulo for the treatment of CIDP, which resulted in an expense of $102 million.Selling, general and administrative expenses for the fourth quarter and full year in 2023 were $209 million and $712 million, respectively, compared to $135 million and $472 million for the same periods in 2022. The selling, general and administrative expenses mainly relate to professional and marketing fees linked to the commercialization of VYVGART and VYVGART SC, and personnel expenses. Financial income for the fourth quarter and full year in 2023 was $40 million and $107 million, respectively, compared to $14 million and $28 million for the same periods in 2022. The increase in financial income is mainly due to an increase in interest income which results from higher interest rates and a higher amount of current financial assets, cash and cash equivalents as a result of the financing round in July 2023. Exchange gains for the fourth quarter and full year in 2023 were $37 million and $14 million respectively, compared to $60 million of exchange gains and $33 million of exchange losses for the same periods in 2022. Exchange gains/losses are mainly attributable to unrealized exchange rate gains or losses on the cash, cash equivalents and current financial assets denominated in Euro. Income tax for the fourth quarter and full year in 2023 was $38 million of tax expense and $9 million of tax benefit, respectively, compared to $3 million and $20 million of tax benefit for the same periods in 2022. Tax expense for the fourth quarter in 2023, consists of $12 million of income tax benefit and $50 million of deferred tax expense, compared to $12 million of income tax expense and $15 million of deferred tax benefit for the comparable prior period. Net loss for the fourth quarter and full year in 2023, was $99 million and $295 million, respectively, compared to $39 million and $710 million over the prior year periods. On a per weighted average share basis, the net loss was $5.16 and $13.05 for the twelve months ended December 31, 2023 and 2022, respectively. Cash, cash equivalents and current financial assets totalled $3.2 billion as of December 31, 2023, compared to $2.2 billion as of December 31, 2022. The increase in cash and cash equivalents and current financial assets resulted primarily from the closing of a global offering of shares, including a U.S. offering, which resulted in the receipt of $1.2 billion in net proceeds in July 2023, partially offset by net cash flows used in operating activities. FINANCIAL GUIDANCE Based on its current operating plans, argenx expects its combined Research and development and Selling, general and administrative expenses in 2024 to be less than $2 billion. argenx expects to utilize up to $500 million of net cash in 2024 on these anticipated operating expenses as well as working capital and capital expenditures. EXPECTED 2024 FINANCIAL CALENDAR May 9, 2024: Q1 2024 financial results and business updateJuly 25, 2024: Q2 2024 financial results and business updateOctober 31, 2024: Q3 2024 financial results and business update CONFERENCE CALL DETAILS The full year 2023 financial results and fourth quarter business update will be discussed during a conference call and webcast presentation today at 2:30 pm CET/8:30 am ET. A webcast of the live call may be accessed on the Investors section of the argenx website at argenx.com/investors. A replay of the webcast will be available on the argenx website. Dial-in numbers: Please dial in 15 minutes prior to the live call. Belgium 32 800 50 201France 33 800 943355Netherlands 31 20 795 1090United Kingdom 44 800 358 0970United States 1 888 415 4250Japan 81 3 4578 9081Switzerland 41 43 210 11 32 About argenx argenx is a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases. Partnering with leading academic researchers through its Immunology Innovation Program (IIP), argenx aims to translate immunology breakthroughs into a world-class portfolio of novel antibody-based medicines. argenx developed and is commercializing the first approved neonatal Fc receptor (FcRn) blocker, globally in the U.S., Japan, Israel, the EU, the UK, China and Canada. The Company is evaluating efgartigimod in multiple serious autoimmune diseases and advancing several earlier stage experimental medicines within its therapeutic franchises. For more information, visit www.argenx.com and follow us on LinkedIn, Twitter, and Instagram. For further information, please contact: Media:Ben Petokbpetok@argenx.com Investors:Alexandra Roy (US)aroy@argenx.com Lynn Elton (EU)lelton@argenx.com Forward-looking Statements The contents of this announcement include statements that are, or may be deemed to be, “forward-looking statements.” These forward-looking statements can be identified by the use of forward-looking terminology, including the terms “plans,” “aims,” “continues,” “anticipates,” “expects,” “will,” or “commitment” and include statements argenx makes concerning its utilization of its learnings and momentum from its gMG launch for a potential CIDP approval and to position VYVGART SC for success; its plans to expand its patient reach, including through its multidimensional expansion efforts aimed at including patients earlier in the MG treatment paradigm and pursuing global regulatory approvals for MG as well as additional autoimmune indications; our goal to translate the ADHERE data into potential benefit for patients; the advancement of, and anticipated clinical development, data readouts and regulatory milestones and plans, including: (1) expected decisions on regulatory approvals of VYVGART for gMG in Switzerland, Australia, Saudi Arabia and South Korea by end of 2024, (2) expected decisions on approval of VYVGART SC for gMG in China through Zai Lab by end of 2024, (3) expected decisions on approval of VYVGART for ITP in Japan in the first quarter of 2024, (4) expected regulatory submissions of VYVGART SC of CIDP in Japan, Europe, China and Canada in 2024, (5) the expansion of our VYVGART registrational studies into broader MG populations, including in seronegative patients, expected to start in 2024, (6) the update on pre-filled syringe development expected in the first half of 2024, (7) clinical studies expected to support potential approval in gMG and CIDP in 2024, (8) expected update on the path forward for BALLAD study in 2024, (9) expected topline data from Phase 2 RHO in the first half of 2024, (10) expected topline data from Phase 2 ALPHA study in the first half of 2024, (11) expected topline data from Phase 2/3 ALKIVIA in the second half of 2024, (12) the full Phase 2 topline data from ARDA study expected in 2024, (13) planned Phase 1b/2a clinical trials of ARGX-119 in 2024, (14) four IND applications expected to be filed by end of 2025, (15) expected data from six Phase 2 proof-of-concept trials by the end of 2024, and (16) the expected approval or development in 15 autoimmune indications by 2025; the potential of its continued investment in its IIP to drive long-term sustainable pipeline growth; its future financial and operating performance, including its anticipated operating expenses and utilization of net cash for 2024; and our goal of translating immunology breakthroughs into a world-class portfolio of novel antibody-based medicines. By their nature, forward-looking statements involve risks and uncertainties and readers are cautioned that any such forward-looking statements are not guarantees of future performance. argenx’s actual results may differ materially from those predicted by the forward-looking statements as a result of various important factors, including but not limited to, the results of argenx’s clinical trials, expectations regarding the inherent uncertainties associated with development of novel drug therapies, preclinical and clinical trial and product development activities and regulatory approval requirements, the acceptance of our products and product candidates by our patients as safe, effective and cost-effective, and the impact of governmental laws and regulations on our business. A further list and description of these risks, uncertainties and other risks can be found in argenx’s U.S. Securities and Exchange Commission (SEC) filings and reports, including in argenx’s most recent annual report on Form 20-F filed with the SEC as well as subsequent filings and reports filed by argenx with the SEC. Given these uncertainties, the reader is advised not to place any undue reliance on such forward-looking statements. These forward-looking statements speak only as of the date of publication of this document. argenx undertakes no obligation to publicly update or revise the information in this press release, including any forward-looking statements, except as may be required by law.