Mallinckrodt Announces Publication of Real-World Data on the Use of Extracorporeal Photopheresis (ECP) in Heart Transplant Patients

- Results from the largest European and first multicenter,retrospective,observational chart review study investigating the real-world use of ECP in heart transplant patients reinforce its use as a treatment for heart transplant rejection and prevention of rejection1-

DUBLIN,June 19,2023 -- Mallinckrodt plc (NYSE American: MNK),a global specialty pharmaceutical company,today announced the publication of findings from a retrospective,observational,single arm,European chart review study assessing the real-world use of extracorporeal photopheresis (ECP) and its impact on clinical outcomes in the modern era of heart transplantation.1 An online version of the data manuscript – the largest-known study of ECP in heart transplant patients – is currently published on the Journal of Heart and Lung Transplantation website in advance of print publication in the second half of 2023.

Interim results of this study were presented in a late-breaking session at the 20th Congress of the European Society for Organ Transplantation (ESOT) in 2021 in Milan,Italy.2

The study,titled "European Multicenter Study on The Real-World Use and Clinical Impact of Extracorporeal Photopheresis After Heart Transplantation," examined data from the medical charts of 105 patients who received ECP following heart transplantation at seven medical centers in Austria,Germany,France,Hungary,and Italy between 2015 – 2021. At time of data extraction,58 patients (55.2%) had completed their ECP treatment and 47 patients' (44.8%) ECP treatment was ongoing.1

"These findings from the largest European and first multicenter study investigating the real-world use of ECP in heart transplant patients support ECP as a treatment for various types of graft rejection and in prevention of graft rejection with varied treatment schedules,1" said Markus Barten,M.D.,Surgical Director of Heart Failure Clinic,University Heart and Vascular Center Hamburg. "This data not only builds upon the growing body of real-world evidence supporting the use of ECP in heart transplant patients,but also reflects the importance of supporting clinicians with treatment modalities for transplant rejection and stabilization.1"

About the Study1

Mean age of patients at start of ECP was 47.7 (SD 14.4) years (min. 16 years to max. 74 years),and most patients (70.5%) were male. They were followed for a mean time of 25.1 (SD 16.8) months from ECP treatment initiation to last visit at the transplant center (follow-up time for outcome overall survival). Mean time from ECP treatment initiation to last visit right censored at 2 years after the end of ECP treatment was 22.5 (SD 13.7) months (follow-up time for outcomes graft function,response,and complications).

Cardiomyopathy was the primary reason for heart transplantation (n=81 patients; 77.1%),followed by coronary heart disease (n=11 patients; 10.5%),heart valve disease (n=5 patients; 4.8%),and myocarditis (n=5 patients; 4.8%). The main reason to start ECP treatment was acute cellular rejection (ACR; n=37 patients; 35.2%),followed by prevention of rejection (n=34 patients; 32.4%),mixed rejection (n=19 patients; 18.1%),and antibody-mediated rejection (AMR; n=15 patients; 14.3%).

The prevention of rejection subgroup included patients who started ECP treatment without biopsy-proven rejection and with standard or reduced immunosuppressive therapy.

Key Findings1

Graft function was stable for almost all patients throughout the study who completed ECP and had graft function change assessed (97.2%; n=35/36).

In patients who started ECP to treat ACR,AMR or mixed rejection (n=26),completed ECP treatment and had a biopsy at the start and end of treatment,92.3% (n=24) were classified as responders,having demonstrated an improvement of ACR and/or AMR International Society for Heart and Lung Transplantation (ISHLT) grading after a mean ECP treatment duration of 5.4 months. The remaining patients had stable grades.

In patients who started ECP to prevent rejection (n=34),88.2% (n=30) remained free from any rejection over a mean follow-up of 26 months despite being considered at high risk for rejection and reduced immunosuppressive therapy.

All patients started ECP treatment while on immunosuppressive therapy,and almost all remained on immunosuppressants until last reported visit prior to data extraction. Tacrolimus and mycophenolate derivatives were the most frequently used immunosuppressants. The number of patients on steroid therapy decreased slightly over time.

Among patients with ongoing ECP treatment who remained on steroid therapy (n=34),steroid dose was reduced on average by 63.0% from start of ECP to last reported visit for 41.2% (n=14) of patients. Steroid dose increased for 5.9% (n=2) of patients and was stable in 52.9% (n=18) of patients.

Among patients who completed ECP treatment and remained on steroid therapy (n=42),steroid dose was reduced on average by 67.0% from start of ECP to last reported visit for 52.4% (n=22) of patients. Steroid dose increased for 4.8% (n=2) of patients and was stable in 42.9% (n=18) of patients.

Amongst the 19 patients in the prevention group,16 (84.2%) received tacrolimus at the start of ECP and last reported visit. In 11/16 patients,tacrolimus trough levels were available of which 7 (63.6%) patients experienced an average trough level decrease of 34.0%.

Amongst the 19 patients in the prevention group,14 (70.4%) received mycophenolate derivatives at the start of ECP and last reported visit. In 4/14 patients,mycophenolate doses were available of which 100% of patients remained on stable mycophenolate derivate dose.

Seventeen of 105 included patients (16.2%) experienced a complication after ECP treatment initiation,the most common of which was infections (n=13,12.4%). Four of 105 patients (3.8%) experienced an endocrine/respiratory/blood/cardiac disorder,2 patients (1.9%) an intolerance of high-dose immunosuppressive therapy,and 1 patient (1.0%) an acute kidney injury.

Overall survival was 95.2% (n=100) over a mean follow-up of 25.1 (SD 16.8) months. Of the 5 deceased patients,3 (60.0%) died with a functioning graft and 4 (80.0%) died after end of ECP treatment. No deaths were related to ECP.

No major safety events occurred. Eighteen of 105 included patients (17.1%) had at least one ECP-related safety event,the most common of which was complications with venous access (n=13; 12.4%). Two (15.4%,n=2/13) patients stopped their ECP treatment as a result. Furthermore,6/105 patients (5.7%) had ECP-related anemia,3 patients (2.9%) ECP-related hypotension,1 patient (1.0%) ECP-related fever,and 2 patients (1.9%) had an unspecified ECP-related safety event,but none of them discontinued their ECP treatment as a result.

Limitations1

The effectiveness of ECP in comparison with other treatment options was not assessed due to the descriptive,single-arm design of this study. Study limitations include that data generation for this observational study was not standardized. Patient examination schedules varied and not all data were available at all centers. No source data verification was performed and therefore,transmission errors cannot be excluded. Not all demonstrated benefits may be solely attributable to ECP treatment,as transplanted patients may have received multiple therapies at time of ECP treatment. In patients with AMR or mixed rejection,ECP is commonly used in combination with other treatments.

This study was funded by Mallinckrodt.

IMPORTANT SAFETY INFORMATION FOR JAPAN

Intended Use or Efficacy

This system is used as extracorporeal photopheresis therapy in steroid resistant or intolerant,chronic graft versus host disease.

Warnings

Directions for Use:

When conducting extracorporeal photopheresis therapy for patients receiving other therapy,exercise caution when changing treatment schedules to avoid increased disease activity that may be caused by abrupt withdrawal of previous therapy.

Taking into account the condition of the patient,administer an appropriate amount of anticoagulant through the CELLEX device,as thromboembolic events may occur.

Contraindications / Prohibitions

Directions for Use:

Do not re-use (Procedural Kit and Methoxsalen Solution).

Do not operate the instrument in the presence of flammable anesthetic gases,external radio or electromagnetic disturbances that may interfere with proper performance of the device. [There is the risk of ignition and malfunction.]

Applicable subject (patient)

Do not use for the following population.

Patients who cannot tolerate extracorporeal volume loss. [Because the patient has possibility of hypotension and shock disease.]

Patients exhibiting idiosyncratic reactions to psoralen compounds including methoxsalen,or possessing a specific history of a light-sensitive disease state.

Patients with aphakia. [Because of the significantly increased risk of retinal damage due to the absence of a lens.]

Patients possessing a specific history of a disordered coagulation or patients who have had previous splenectomy. [Anticoagulants is used during therapy.]

Patients during pregnancy and lactation. [There is likely to cause harm to the unborn child or suckling infant.]

Patients who have white blood cell counts greater than 25,000/mm3. [Design limit for sensor on instrument.]

ABOUT THE THERAKOS CELLEX ECP SYSTEM FOR JAPAN

The CELLEX System delivers extracorporeal photopheresis (ECP),and consists of an instrument,procedural kit,methoxsalen solution and a UVA lamp.

The CELLEX System was designated as a medical device to be introduced early in Japan by the 15th Study Panel on Early Introduction of Highly Needed Medical Devices. This meeting was organized by the MHLW and held on February 17,2011.

CELLEX was also designated as an orphan medical device by the MHLW on January 18,2017.

APPROVED USES FOR THE THERAKOS CELLEX ECP SYSTEM

The approved uses for CELLEX ECP differ depending upon the country. Please refer to each country's Operator's manuals and labeling for approved uses.

About Extracorporeal Photopheresis (ECP)

ECP,a blood based immunomodulatory therapy developed more than 30 years ago,is recommended by the International Society for Heart and Lung Transplantation (ISHLT)3and other clinical societies4,5,6as an adjunctive therapy for the prevention and treatment of ACR after heart transplantation. Additionally,ECP may be considered to treat AMR with or without donor specific antibodies.7,8In countries where it is approved,ECP is used to treat a range of immune-mediated diseases,including skin manifestations of cutaneous T-cell lymphoma (CTCL),graft-versus-host disease (GvHD),solid organ transplant rejection and other autoimmune diseases. During ECP treatment,a small amount of white blood cells is collected and treated with a drug that is activated by ultraviolet light.

ABOUTMALLINCKRODT

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; cultured skin substitutes and gastrointestinal products. Its Specialty Generics reportable segment includes specialty generic drugs and active pharmaceutical ingredients. To learn more about Mallinckrodt,visitwww.mallinckrodt.com.

Mallinckrodtuses its website as a channel of distribution of important company information,such as press releases,investor presentations and other financial information. It also uses its website to expedite public access to time-critical information regarding the company in advance of or in lieu of distributing a press release or a filing with theU.S. Securities and Exchange Commission(SEC) disclosing the same information. Therefore,investors should look to the Investor Relations page of the website for important and time-critical information. Visitors to the website can also register to receive automatic e-mail and other notifications alerting them when new information is made available on the Investor Relations page of the website.

CAUTIONARY STATEMENTS RELATED TO FORWARD-LOOKING STATEMENTS

This release contains forward-looking statements,including with regard to ECP and 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: satisfaction of 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; 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

Heather Guzzi

Senior Vice President,Green Room Communications

973-524-4112

hguzzi@grcomms.com

Investor Relations

Daniel J. Speciale

Global Corporate Controller & Chief Investor Relations Officer

314-654-3638

daniel.speciale@mnk.com

Derek Belz

Vice President,Investor Relations

314-654-3950

derek.belz@mnk.com

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©2023 Mallinckrodt.JP-2300005 06/23

1 Barten,MJ et al. European multi-center study on the real-world use and clinical impact of extracorporeal photopheresis after heart transplantation. J Heart Lung Transplant. 2023. https://doi.org/10.1016/j.healun.2023.03.005.

2 Barten,MJ. et al. Real World Use and Clinical Impact of Extracorporeal Photopheresis in Heart Transplant Patients – Results From a European Multi-Centre Study. Abstract presented at: European Society for Organ Transplantation (ESOT) Congress 2021. August/September 2021.

3 Costanzo MR,et al. The International Society of Heart and Lung Transplantation Guidelines for the care of heart transplant recipients. J Heart Lung Trans. 2010:29(8);914–956.

4 Alfred et al. The role of extracorporeal photopheresis in the management of cutaneous T-cell lymphoma,graft-versus-host disease and organ transplant rejection: a consensus statement update from the UK Photopheresis Society. Br J Haematol. 2017;177(2):287-310.

5 Padmanabhan et al. Guidelines on the Use of Therapeutic Apheresis in Clinical Practice - Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Eighth Special Issue. J Clin Apher. 2019;34:171–354.

6 Knobler et al. European dermatology forum - updated guidelines on the use of extracorporeal photopheresis 2020 - part 2. Eur Acad Dermatol Venereol. 2021;35(1):27-49.

7 Colvin et al. Antibody-mediated rejection in cardiac transplantation: emerging knowledge in diagnosis and management: a scientific statement from the American Heart Association. Circulation. 2015;131(18):1608-1639.

8 Barten et al. Transplant Rev (Orlando). The clinical impact of donor-specific antibodies in heart transplantation. 2018;32(4):207-217.

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