Business Wire | Feb 24, 2021 07:00AM EST

Horizon Therapeutics plc Reports Record Fourth-Quarter and Full-Year 2020 Financial Results; Announces Full-Year 2021 Guidance

Feb. 24, 2021

DUBLIN--(BUSINESS WIRE)--Feb. 24, 2021--Horizon Therapeutics plc (Nasdaq: HZNP) today announced record fourth-quarter and full-year 2020 financial results and provided full-year 2021 net sales and adjusted EBITDA guidance.

"Our outperformance in 2020 capped off a breakthrough year for Horizon," said Tim Walbert, chairman, president and chief executive officer, Horizon. "The launch of TEPEZZA, one of the most successful rare disease medicine launches ever, strengthened our position as one of the fastest growing biotech companies. Our recently announced agreement to acquire Viela further strengthens this position by adding a deep mid-stage biologics pipeline and an on-market rare disease biologic, UPLIZNA. This significant progress allows us to build on the value we provide to patients and our shareholders."

FinancialHighlights (in millionsexcept for % %per share Q4 20 Q4 19 Change FY 20 FY 19 Changeamounts andpercentages) $ $ $ 2,200.4 $ 1,300.0 69 Net sales 745.3 363.5 105

) )Net income 190.6 592.8 (68 389.8 573.0 (32

Non-GAAP net 120 income 298.5 116.6 156 857.6 390.2

Adjusted 107 EBITDA 371.0 139.9 165 998.7 482.8

Earnings per ) )share - 0.82 2.84 (71 1.81 2.90 (38dilutedNon-GAAP earnings per 1.28 0.56 129 3.88 1.94 100 share -diluted Fourth-Quarter and Recent Company Highlights

* Pending Acquisition of Viela Bio, Inc.: On Jan. 31, 2021, the Company entered into a definitive agreement to acquire Viela, a biotechnology company with a deep, mid-stage biologics pipeline for autoimmune and severe inflammatory diseases, an experienced R&D team and UPLIZNA, a recently approved biologic medicine for a rare disease. The acquisition represents a significant step forward in advancing the Company's strategy to expand its pipeline to accelerate long-term sustainable growth by adding four pipeline candidates currently in nine development programs. Per the agreement, the Company will acquire all of Viela's common stock for $53.00 per share in cash, which represents a fully diluted equity value of approximately $2.67 billion, net of Viela's cash and cash equivalents. The transaction is expected to close by the end of the first quarter of 2021. * TEPEZZA Supply Update: In January 2021, the Company submitted a prior approval supplement to the U.S. Food and Drug Administration (FDA) to support increased scale production of TEPEZZA drug product for the treatment of Thyroid Eye Disease (TED). The submission includes data to support more drug product output with each manufacturing slot than is currently approved by the FDA. The Company will continue to discuss potential additional data requirements and the approval timeline with the FDA. The Company continues to expect that the disruption could last through the first quarter of 2021. As previously announced on Dec. 17, 2020, this increased production scale became necessary due to government-mandated COVID-19 vaccine production orders pursuant to the Defense Production Act of 1950 (DPA) that dramatically reduced the number of drug product production slots available to Horizon at the Company's drug product contract manufacturer of TEPEZZA. * Entered into Agreement with Halozyme to Develop a TEPEZZA Subcutaneous (SC) Formulation: On Nov. 21, 2020, the Company and Halozyme Therapeutics, Inc. entered into a global collaboration and license agreement for exclusive access to Halozyme's ENHANZE(r) drug delivery technology for subcutaneous formulation of medicines targeting IGF-1R. The Company intends to use ENHANZE to develop a SC formulation of TEPEZZA, potentially shortening drug administration time, reducing healthcare practitioner time and offering additional flexibility and convenience for patients. * Completed Enrollment in KRYSTEXXA PROTECT Trial: In January 2021, the Company completed enrollment in the PROTECT open-label trial. The trial, which is evaluating KRYSTEXXA to improve the management of uncontrolled gout for adults with a kidney transplant, had a total enrollment of 20 patients. Results are expected in the fourth quarter of 2021. In October 2020, the Company announced interim data from the PROTECT trial that were encouraging with respect to the ability of KRYSTEXXA to treat uncontrolled gout in this very sensitive transplant population without compromising kidney function. * Announced Two New KRYSTEXXA Trials to Impact the Patient Experience and Broaden the Patient Population: The Company recently announced it is planning to initiate two new KRYSTEXXA trials in the first half of 2021. The KRYSTEXXA monthly dosing open-label trial is evaluating a monthly dosing regimen of KRYSTEXXA with methotrexate to treat people with uncontrolled gout. The current dosing schedule for KRYSTEXXA is every other week. The KRYSTEXXA retreatment open-label trial is evaluating KRYSTEXXA with methotrexate in patients who have previously failed on KRYSTEXXA. In addition, in October, the Company enrolled the first patient in its open-label shorter infusion duration trial, which is evaluating a shorter infusion duration of KRYSTEXXA with methotrexate. The current infusion time is two hours or longer. * New TEPEZZA Clinical Data Presented at Medical Meetings: New TEPEZZA data were presented at the virtual American Academy of Ophthalmology (AAO) Annual Meeting in November, including data from the OPTIC 48-week follow-up study and OPTIC-X clinical trial that demonstrated a durable response. In addition, case studies of 21 chronic TED patients who showed benefit after treatment with TEPEZZA were presented at the virtual Fall Symposium of the American Society of Ophthalmic Plastic and Reconstructive Surgery (ASOPRS) in November. This adds to the growing body of evidence supporting the use of TEPEZZA in chronic TED patients, with approximately 30 chronic TED patients across multiple case reports who have consistently demonstrated benefit. * KRYSTEXXA Immunomodulation RECIPE Trial Achieved 86 Percent Response Rate: In November, data were presented from the investigator-initiated RECIPE randomized controlled trial (RCT), evaluating the effect of co-administration of KRYSTEXXA with mycophenolate mofetil (MMF) to increase the complete response rate of KRYSTEXXA, with 86 percent of patients receiving KRYSTEXXA co-administered with MMF achieving the primary endpoint of serum uric acid (sUA) less than or equal to 6 mg/dL at 12 weeks, compared to 40 percent of placebo patients on KRYSTEXXA monotherapy (p-value 0.01). After 12 weeks off of MMF therapy but continuing on KRYSTEXXA therapy, 68 percent of patients achieved a sustained response, compared to 30 percent of placebo patients. The combination was well tolerated with no new safety signals. This trial adds to the growing body of evidence supporting the immunomodulation treatment approach where complete response rates have ranged between 70 and 100 percent. * Established Scholarship Endowments to Foster Equity in Education: In December, the Company announced that it provided $1 million to endow scholarships to be awarded to economically disadvantaged students and students of color at Howard University and in a joint health professionals program at Lake Forest College and Rosalind Franklin University. This adds to the Company's efforts to combat racism and foster inclusion, which includes a $500,000 donation to community organizations that are addressing racial inequality and racism, as well as internal efforts within the Company to further embed inclusion, diversity, equity and allyship at all levels of the organization. * Received Continued Recognition as a Best Workplace: In 2020, the Company received 13 workplace-related recognitions, including six in the fourth quarter, reflecting the high level of engagement of its employees. Horizon was named to the following lists in the fourth quarter: Fortune Best Small & Medium Workplaces(tm); Great Place to Work's 2020 Best Workplaces for Parents(tm); National Association for Business Resources' 2020 Best and Brightest Companies to Work For in the Nation(r); Chicago Tribune Top Workplaces 2020; San Francisco Bay Area's 2020 Best and Brightest Companies to Work For(r); and Dave Thomas Foundation for Adoption Best Adoption-Friendly Workplace(tm) list.

Key Research and Development Programs

* HZN-825 Diffuse Cutaneous Systemic Sclerosis Program: HZN-825 is an LPAR1 antagonist in development for the treatment of diffuse cutaneous systemic sclerosis (dcSSc), a rare, chronic autoimmune disease marked by fibrosis, or skin thickening, with no FDA-approved treatment options. The Company expects to begin a Phase 2b pivotal trial in the first half of 2021 with the primary endpoint of forced vital capacity after 52 weeks of treatment. * HZN-825 Interstitial Lung Disease Program: As part of its strategy to further explore the potential fibrosis-mediating benefits of LPAR1 antagonism, in mid-2021, the Company expects to begin a Phase 2b pivotal trial with HZN-825 in idiopathic pulmonary fibrosis (IPF), the most common form of interstitial lung disease. IPF is a rare progressive lung disease with a median survival of less than five years with significant unmet need. * TEPEZZA Trial in Chronic TED: The Company expects to initiate a randomized, placebo-controlled trial of TEPEZZA in patients with chronic TED in the second quarter of 2021, assuming normalized supply of TEPEZZA. In chronic TED, the disease is no longer progressive; however, significant disease manifestations such as proptosis (eye bulging) and diplopia (double vision) remain. Although the prescribing information for TEPEZZA includes chronic TED patients, the Company is conducting the trial to generate clinical data to better inform payers and physicians about the use of TEPEZZA in chronic TED. * TEPEZZA Subcutaneous (SC) Administration Program: The Company has initiated a pharmacokinetic trial to explore SC dosing of TEPEZZA, which is currently administered by infusion. The objective of the trial is to inform the potential for additional administration options for TEPEZZA, which could provide greater flexibility for patients and physicians. The TEPEZZA SC administration program includes evaluating Halozyme's ENHANZE drug delivery technology for a SC formulation of TEPEZZA, with initial early clinical work expected to begin in 2021. * TEPEZZA dcSSc Exploratory Trial: As part of its evaluation of additional potential indications for TEPEZZA, the Company is planning to initiate an exploratory trial in dcSSc by mid-2021, assuming normalized supply of TEPEZZA. * KRYSTEXXA MIRROR Randomized Controlled Trial: The Company is currently evaluating the efficacy and safety of the concomitant use of KRYSTEXXA with methotrexate to increase the complete response rate of KRYSTEXXA in the MIRROR RCT. The primary endpoint of the trial is the proportion of sUA responders (sUA of less than 6 mg/dL) at six months, with secondary endpoints out to 12 months. The registrational trial is designed to enable the submission of results to the FDA to potentially update the prescribing information. The MIRROR RCT follows the MIRROR open-label trial completed in 2019 that demonstrated a 79 percent complete response rate for patients using KRYSTEXXA with methotrexate, nearly double the 42 percent response rate in the KRYSTEXXA Phase 3 clinical program, which evaluated KRYSTEXXA alone. Methotrexate is the immunomodulator most used by rheumatologists and has been shown to reduce anti-drug antibody formation to biologic therapies when used in conjunction with these therapies. * KRYSTEXXA PROTECT Trial in Kidney Transplant Patients with Uncontrolled Gout: In January 2021, the Company completed enrollment of 20 patients in the PROTECT open-label trial, evaluating KRYSTEXXA to improve management of uncontrolled gout for adults with a kidney transplant. Kidney transplant patients have more than a tenfold increase in the prevalence of gout when compared to the general population, and literature suggests that persistently high sUA levels can be associated with organ rejection. Managing uncontrolled gout is one of the most common and significant unmet needs of kidney transplant patients. * KRYSTEXXA Shorter Infusion Duration Trial: In October 2020, the Company enrolled the first patient in its shorter infusion duration trial to evaluate the impact of administering KRYSTEXXA over a significantly shorter infusion duration. Currently, KRYSTEXXA is infused over a two-hour or longer timeframe. A shorter infusion duration administration could meaningfully impact the experience for patients, physicians and sites of care. * KRYSTEXXA Monthly Dosing Trial: The Company is planning to initiate an open-label trial evaluating a monthly dosing regimen of KRYSTEXXA with methotrexate to treat people with uncontrolled gout. The current dosing schedule for KRYSTEXXA is every other week. The goal of the trial is to explore whether a monthly dosing regimen can provide similar outcomes as the current dosing schedule. The trial is expected to initiate in the first half of 2021. * KRYSTEXXA Retreatment Trial: The Company is planning to initiate an open-label trial evaluating KRYSTEXXA with methotrexate in patients who have previously failed KRYSTEXXA. The goal of the trial is to evaluate whether patients can benefit from KRYSTEXXA with methotrexate after developing an immune response to KRYSTEXXA when taken alone. Patients who have previously failed on KRYSTEXXA have limited options available to address their uncontrolled gout. The trial is expected to initiate in the first half of 2021.

Fourth-Quarter Financial Results

Note: For additional detail and reconciliation of non-GAAP financial measures to the most directly comparable GAAP financial measures, please refer to the tables at the end of this release.

* Net Sales: Fourth-quarter 2020 net sales were $745.3 million, an increase of 105 percent compared to the fourth quarter of 2019.

* Gross Profit: Under U.S. GAAP, the fourth-quarter 2020 gross profit ratio was 78.2 percent compared to 73.9 percent in the fourth quarter of 2019. The non-GAAP gross profit ratio in the fourth quarter of 2020 was 87.1 percent compared to 90.0 percent in the fourth quarter of 2019.

* Operating Expenses: Research and development (R&D) expenses were 9.5 percent of net sales and selling, general and administrative (SG&A) expenses were 37.2 percent of net sales. Non-GAAP R&D expenses were 5.2 percent of net sales, and non-GAAP SG&A expenses were 32.3 percent of net sales.

* Income Tax Expense: In the fourth quarter of 2020, income tax expense on a GAAP and non-GAAP basis was $39.0 million and $61.6 million, respectively.

* Net Income: On a GAAP basis in the fourth quarter of 2020, net income was $190.6 million. Fourth-quarter 2020 non-GAAP net income was $298.5 million.

* Adjusted EBITDA: Fourth-quarter 2020 adjusted EBITDA was $371.0 million.

* Earnings per Share: On a GAAP basis diluted earnings per share in the fourth quarter of 2020 and 2019 was $0.82 and $2.84, respectively. Non-GAAP diluted earnings per share in the fourth quarter of 2020 and 2019 was $1.28 and $0.56, respectively. Weighted average shares outstanding used for calculating GAAP and non-GAAP diluted earnings per share in the fourth quarter of 2020 were 232.9 million.

Fourth-Quarter Segment Results



Management uses net sales and segment operating income to evaluate theperformance of the Company's two segments, the orphan segment and theinflammation segment. While segment operating income contains certainadjustments to the directly comparable GAAP figures in the Company'sconsolidated financial results, it is considered to be prepared in accordancewith GAAP for purposes of presenting the Company's segment operating results.

OrphanSegment

(in millions % %except for Q4 20 Q4 19 Change FY 20 FY 19 Changepercentages) NM NM TEPEZZA^(r) 343.7 - 820.0 -

KRYSTEXXA^ 110.7 16 342.4 19 (r) 128.9 405.9

RAVICTI^(r) 3 228.8 14 (1) 70.2 68.5 261.6

161.9 5 PROCYSBI^(r) 47.3 40.8 16 170.1

ACTIMMUNE^ 26 107.3 11 (r) 35.7 28.4 118.8

BUPHENYL^(r) 32 (1) 2.2 1.6 10.6 9.8 8

(25 ) (15 )QUINSAIR^TM 0.2 0.3 0.7 0.8

Orphan Net $ 628.2 $ 250.3 151 $ 1,787.7 $ 851.0 110 Sales OrphanSegment $ 303.0 $ 83.3 264 $ 783.6 $ 263.3 198 OperatingIncome(1)

On Oct. 27, 2020, the Company sold its rights to develop and commercialize RAVICTI(r) and BUPHENYL(r) in Japan to Medical Need Europe AB, part of the Immedica Group. The Company has retained the rights to RAVICTI and BUPHENYL in North America.

* Fourth-quarter 2020 net sales of the orphan segment, the Company's strategic growth segment, were $628.2 million, an increase of 151 percent over the prior year's quarter, driven by the strong performance of TEPEZZA, KRYSTEXXA, PROCYSBI and ACTIMMUNE. The orphan segment represented 84 percent of total fourth-quarter net sales.

* Fourth-quarter 2020 orphan segment operating income was $303.0 million, which includes significant investment spend associated with the commercial launch of TEPEZZA.

On Oct. 27, 2020, the Company sold its rights to develop and(1) commercialize RAVICTI^(r) and BUPHENYL^(r) in Japan to Medical Need Europe AB, part of the Immedica Group. The Company has retained the rights to RAVICTI and BUPHENYL in North America.

* Fourth-quarter 2020 net sales of the orphan segment, the Company's strategic growth segment, were $628.2 million, an increase of 151 percent over the prior year's quarter, driven by the strong performance of TEPEZZA, KRYSTEXXA, PROCYSBI and ACTIMMUNE. The orphan segment represented 84 percent of total fourth-quarter net sales.

* Fourth-quarter 2020 orphan segment operating income was $303.0 million, which includes significant investment spend associated with the commercial launch of TEPEZZA.

InflammationSegment

(in millions Q4 20 Q4 19 % FY 20 FY 19 %except for Change Changepercentages) PENNSAID 51.1 (10 ) 178.0 (11 )2%^(r) 57.0 200.8

38.3 45 125.3 8 DUEXIS^(r) 26.3 115.7

21.0 8 (9 ) RAYOS^(r) 19.5 71.8 78.6

VIMOVO^(r) (35 ) (28 )(1) 6.7 10.4 37.6 52.1

MIGERGOT^ NM NM (r)(2) - - - 1.8

Inflammation $ 117.1 $ 113.2 3 $ 412.7 $ 449.0 (8 )Net Sales InflammationSegment $ 66.9 $ 56.2 19 $ 212.1 $ 217.9 (3 )OperatingIncome (1)

On Feb. 27, 2020, Dr. Reddy's Laboratory initiated an at-risk launch of generic VIMOVO in the United States.

(2)

In June 2019, the Company divested the rights to MIGERGOT.

* Fourth-quarter 2020 net sales of the inflammation segment were $117.1 million, and segment operating income was $66.9 million.

Cash Flow Statement and Balance Sheet Highlights

* On a GAAP basis, operating cash flow in the fourth quarter of 2020 was $409.8 million. Non-GAAP operating cash flow was $411.2 million.

* As of Dec. 31, 2020, the Company had cash and cash equivalents of $2.080 billion.

* As of Dec. 31, 2020, the total principal amount of debt outstanding was $1.018 billion. As of Dec. 31, 2020, the gross-debt-to-last-12-months adjusted EBITDA leverage ratio was 1.0 times, compared to 2.9 times as of Dec. 31, 2019.

2021 Guidance

The Company expects full?year 2021 net sales to range between $2.70 billion and $2.80 billion, representing 25 percent growth at the midpoint. The Company expects TEPEZZA full-year 2021 net sales of greater than $1.275 billion and KRYSTEXXA full-year 2021 net sales of greater than $500 million. Full-year 2021 adjusted EBITDA is expected to range between $1.14 billion and $1.18 billion, representing 16 percent growth at the midpoint. The Company's guidance assumes FDA approval of the increased scale drug product manufacturing process of TEPEZZA and the successful completion of future committed manufacturing slots for TEPEZZA and does not reflect the potential impact of the operations of Viela following the close of the acquisition, which is expected to occur by the end of first quarter of 2021, and which would result in an expected reduction of full-year 2021 adjusted EBITDA of approximately $140 million.

Webcast

At 8 a.m. EST / 1 p.m. IST today, the Company will host a live webcast to review its financial and operating results and provide a general business update. The live webcast and a replay may be accessed at http://ir.horizontherapeutics.com. Please connect to the Company's website at least 15 minutes prior to the live webcast to ensure adequate time for any software download that may be needed to access the webcast. A replay of the webcast will be available approximately two hours after the live webcast.

About Horizon

Horizon is focused on researching, developing and commercializing medicines that address critical needs for people impacted by rare and rheumatic diseases. Our pipeline is purposeful: we apply scientific expertise and courage to bring clinically meaningful therapies to patients. We believe science and compassion must work together to transform lives. For more information on how we go to incredible lengths to impact lives, please visit www.horizontherapeutics.com and follow us on Twitter, LinkedIn, Instagram and Facebook.

Note Regarding Use of Non-GAAP Financial Measures

EBITDA, or earnings before interest, taxes, depreciation and amortization, and adjusted EBITDA are used and provided by Horizon as non-GAAP financial measures. Horizon provides certain other financial measures such as non-GAAP net income, non-GAAP diluted earnings per share, non-GAAP gross profit and gross profit ratio, non-GAAP operating expenses, non-GAAP operating income,non-GAAP tax rate and non-GAAP operating cash flow, each of which include adjustments to GAAP figures. These non-GAAP measures are intended to provide additional information on Horizon's performance, operations, expenses, profitability and cash flows. Adjustments to Horizon's GAAP figures as well as EBITDA exclude acquisition and/or divestiture-related expenses, charges related to the discontinuation of ACTIMMUNE development for Friedreich's ataxia, gain or loss from divestiture, gain or loss from sale of assets, upfront, progress and milestone payments related to license and collaboration agreements, litigation settlements, loss on debt extinguishment, costs of debt refinancing, drug manufacturing harmonization costs, restructuring and realignment costs, the income tax effect on pre-tax non-GAAP adjustments and other non-GAAP income tax adjustments, as well as non-cash items such as share-based compensation, depreciation and amortization,non-cash interest expense, long-lived asset impairment charges and other non-cash adjustments. Certain other special items or substantive events may also be included in the non-GAAP adjustments periodically when their magnitude is significant within the periods incurred. Horizon maintains an established non-GAAP cost policy that guides the determination of what costs will be excluded in non-GAAP measures. Horizon believes that these non-GAAP financial measures, when considered together with the GAAP figures, can enhance an overall understanding of Horizon's financial and operating performance. The non-GAAP financial measures are included with the intent of providing investors with a more complete understanding of the Company's historical and expected 2021 financial results and trends and to facilitate comparisons between periods and with respect to projected information. In addition, these non-GAAP financial measures are among the indicators Horizon's management uses for planning and forecasting purposes and measuring the Company's performance. For example, adjusted EBITDA is used by Horizon as one measure of management performance under certain incentive compensation arrangements. These non-GAAP financial measures should be considered in addition to, and not as a substitute for, or superior to, financial measures calculated in accordance with GAAP. The non-GAAP financial measures used by the Company may be calculated differently from, and therefore may not be comparable to, non-GAAP financial measures used by other companies. Horizon has not provided a reconciliation of itsfull-year 2021 adjusted EBITDA outlook to an expected net income (loss) outlook because certain items such as acquisition/divestiture-related expenses and share-based compensation that are a component of net income (loss) cannot be reasonably projected due to the significant impact of changes in Horizon's stock price, the variability associated with the size or timing of acquisitions/divestitures and other factors. These components of net income (loss) could significantly impact Horizon's actual net income (loss).

Forward-Looking Statements

This press release contains forward-looking statements, including, but not limited to, statements related to Horizon's full-year 2021 net sales and adjusted EBITDA guidance; expected financial performance and operating results in future periods, including potential growth in net sales of certain of Horizon's medicines; the acquisition of Viela Bio, Inc. and the benefits and other impacts thereof; development and commercialization plans; expected timing of clinical trials, studies and regulatory submissions; potential market opportunity for and benefits of Horizon's medicines and medicine candidates; and business and other statements that are not historical facts. These forward-looking statements are based on Horizon's current expectations and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, risks that Horizon's actual future financial and operating results may differ from its expectations or goals; Horizon's ability to grow net sales from existing medicines; impacts of the COVID-19 pandemic and actions taken to slow its spread, including impacts on supplies and net sales of Horizon's medicines and potential delays in clinical trials; risks associated with acquisitions, such as the risk that closing conditions will not be satisfied, that the businesses will not be integrated successfully, that such integration may be more difficult, time-consuming or costly than expected or that the expected benefits of the transaction will not occur; the availability of coverage and adequate reimbursement and pricing from government and third-party payers; risks relating to Horizon's ability to successfully implement its business strategies; risks inherent in developing novel medicine candidates and existing medicines for new indications; risks associated with regulatory approvals; risks in the ability to recruit, train and retain qualified personnel; competition, including potential generic competition; the ability to protect intellectual property and defend patents; regulatory obligations and oversight, including any changes in the legal and regulatory environment in which Horizon operates and those risks detailed from time-to-time under the caption "Risk Factors" and elsewhere in Horizon's filings and reports with the SEC. Horizon undertakes no duty or obligation to update any forward-looking statements contained in this press release as a result of new information.

(1) On Feb. 27, 2020, Dr. Reddy's Laboratory initiated an at-risk launch of generic VIMOVO in the United States.

(2) In June 2019, the Company divested the rights to MIGERGOT.

* Fourth-quarter 2020 net sales of the inflammation segment were $117.1 million, and segment operating income was $66.9 million.

Cash Flow Statement and Balance Sheet Highlights

* On a GAAP basis, operating cash flow in the fourth quarter of 2020 was $409.8 million. Non-GAAP operating cash flow was $411.2 million.

* As of Dec. 31, 2020, the Company had cash and cash equivalents of $2.080 billion.

* As of Dec. 31, 2020, the total principal amount of debt outstanding was $1.018 billion. As of Dec. 31, 2020, the gross-debt-to-last-12-months adjusted EBITDA leverage ratio was 1.0 times, compared to 2.9 times as of Dec. 31, 2019.

2021 Guidance

The Company expects full?year 2021 net sales to range between $2.70 billion and $2.80 billion, representing 25 percent growth at the midpoint. The Company expects TEPEZZA full-year 2021 net sales of greater than $1.275 billion and KRYSTEXXA full-year 2021 net sales of greater than $500 million. Full-year 2021 adjusted EBITDA is expected to range between $1.14 billion and $1.18 billion, representing 16 percent growth at the midpoint. The Company's guidance assumes FDA approval of the increased scale drug product manufacturing process of TEPEZZA and the successful completion of future committed manufacturing slots for TEPEZZA and does not reflect the potential impact of the operations of Viela following the close of the acquisition, which is expected to occur by the end of first quarter of 2021, and which would result in an expected reduction of full-year 2021 adjusted EBITDA of approximately $140 million.

Webcast

At 8 a.m. EST / 1 p.m. IST today, the Company will host a live webcast to review its financial and operating results and provide a general business update. The live webcast and a replay may be accessed at http://ir.horizontherapeutics.com. Please connect to the Company's website at least 15 minutes prior to the live webcast to ensure adequate time for any software download that may be needed to access the webcast. A replay of the webcast will be available approximately two hours after the live webcast.

About Horizon

Horizon is focused on researching, developing and commercializing medicines that address critical needs for people impacted by rare and rheumatic diseases. Our pipeline is purposeful: we apply scientific expertise and courage to bring clinically meaningful therapies to patients. We believe science and compassion must work together to transform lives. For more information on how we go to incredible lengths to impact lives, please visit www.horizontherapeutics.com and follow us on Twitter, LinkedIn, Instagram and Facebook.

Note Regarding Use of Non-GAAP Financial Measures

EBITDA, or earnings before interest, taxes, depreciation and amortization, and adjusted EBITDA are used and provided by Horizon as non-GAAP financial measures. Horizon provides certain other financial measures such as non-GAAP net income, non-GAAP diluted earnings per share, non-GAAP gross profit and gross profit ratio, non-GAAP operating expenses, non-GAAP operating income,non-GAAP tax rate and non-GAAP operating cash flow, each of which include adjustments to GAAP figures. These non-GAAP measures are intended to provide additional information on Horizon's performance, operations, expenses, profitability and cash flows. Adjustments to Horizon's GAAP figures as well as EBITDA exclude acquisition and/or divestiture-related expenses, charges related to the discontinuation of ACTIMMUNE development for Friedreich's ataxia, gain or loss from divestiture, gain or loss from sale of assets, upfront, progress and milestone payments related to license and collaboration agreements, litigation settlements, loss on debt extinguishment, costs of debt refinancing, drug manufacturing harmonization costs, restructuring and realignment costs, the income tax effect on pre-tax non-GAAP adjustments and other non-GAAP income tax adjustments, as well as non-cash items such as share-based compensation, depreciation and amortization,non-cash interest expense, long-lived asset impairment charges and other non-cash adjustments. Certain other special items or substantive events may also be included in the non-GAAP adjustments periodically when their magnitude is significant within the periods incurred. Horizon maintains an established non-GAAP cost policy that guides the determination of what costs will be excluded in non-GAAP measures. Horizon believes that these non-GAAP financial measures, when considered together with the GAAP figures, can enhance an overall understanding of Horizon's financial and operating performance. The non-GAAP financial measures are included with the intent of providing investors with a more complete understanding of the Company's historical and expected 2021 financial results and trends and to facilitate comparisons between periods and with respect to projected information. In addition, these non-GAAP financial measures are among the indicators Horizon's management uses for planning and forecasting purposes and measuring the Company's performance. For example, adjusted EBITDA is used by Horizon as one measure of management performance under certain incentive compensation arrangements. These non-GAAP financial measures should be considered in addition to, and not as a substitute for, or superior to, financial measures calculated in accordance with GAAP. The non-GAAP financial measures used by the Company may be calculated differently from, and therefore may not be comparable to, non-GAAP financial measures used by other companies. Horizon has not provided a reconciliation of itsfull-year 2021 adjusted EBITDA outlook to an expected net income (loss) outlook because certain items such as acquisition/divestiture-related expenses and share-based compensation that are a component of net income (loss) cannot be reasonably projected due to the significant impact of changes in Horizon's stock price, the variability associated with the size or timing of acquisitions/divestitures and other factors. These components of net income (loss) could significantly impact Horizon's actual net income (loss).

Forward-Looking Statements

This press release contains forward-looking statements, including, but not limited to, statements related to Horizon's full-year 2021 net sales and adjusted EBITDA guidance; expected financial performance and operating results in future periods, including potential growth in net sales of certain of Horizon's medicines; the acquisition of Viela Bio, Inc. and the benefits and other impacts thereof; development and commercialization plans; expected timing of clinical trials, studies and regulatory submissions; potential market opportunity for and benefits of Horizon's medicines and medicine candidates; and business and other statements that are not historical facts. These forward-looking statements are based on Horizon's current expectations and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, risks that Horizon's actual future financial and operating results may differ from its expectations or goals; Horizon's ability to grow net sales from existing medicines; impacts of the COVID-19 pandemic and actions taken to slow its spread, including impacts on supplies and net sales of Horizon's medicines and potential delays in clinical trials; risks associated with acquisitions, such as the risk that closing conditions will not be satisfied, that the businesses will not be integrated successfully, that such integration may be more difficult, time-consuming or costly than expected or that the expected benefits of the transaction will not occur; the availability of coverage and adequate reimbursement and pricing from government and third-party payers; risks relating to Horizon's ability to successfully implement its business strategies; risks inherent in developing novel medicine candidates and existing medicines for new indications; risks associated with regulatory approvals; risks in the ability to recruit, train and retain qualified personnel; competition, including potential generic competition; the ability to protect intellectual property and defend patents; regulatory obligations and oversight, including any changes in the legal and regulatory environment in which Horizon operates and those risks detailed from time-to-time under the caption "Risk Factors" and elsewhere in Horizon's filings and reports with the SEC. Horizon undertakes no duty or obligation to update any forward-looking statements contained in this press release as a result of new information.

Horizon Therapeutics plcConsolidated Statements of Operations(in thousands, except share and per share data) Three Months Ended December 31, Twelve Months Ended December 31,

2020 2019 2020 2019

(Unaudited) Net sales $ 745,314 $ 363,545 $ 2,200,429 $ 1,300,029

Cost of goods 162,289 94,921 362,175 sold 532,695

583,025 268,624 937,854 Gross profit 1,667,734

OPERATING EXPENSES:Research and 70,881 28,558 103,169 development 209,364

Selling, 276,956 185,391 697,111 general and 973,227administrative(Gain)/Loss on (4,883 ) ) 10,963 sale of assets - (4,883

Total 342,954 213,949 811,243 operating 1,177,708expensesOperating 240,071 54,675 126,611 income 490,026

OTHER EXPENSE, NET:Interest (11,516 ) (17,098 ) ) (87,089 )expense, net (59,616

Loss on debt ) (58,835 )extinguishment - - (31,856

Foreign (603 ) ) exchange 58 (297 33(loss) gainOther income 1,597 (751 ) )(expense), net 3,388 (944

Total other (10,522 ) (17,791 ) ) (146,835 )expense, net (88,381

Income (Loss) before expense 229,549 36,884 401,645 (20,224 )(benefit) forincome taxesExpense 38,992 (555,885 ) (593,244 )(benefit) for 11,849income taxesNet income $ 190,557 $ 592,769 $ 389,796 $ 573,020

Net income per $ 0.86 $ 3.16 $ $ 3.13 ordinary share 1.91- basic Weightedaverageordinary 220,929,626 187,421,561 203,967,246 182,930,109 sharesoutstanding -basic Net income per $ 0.82 $ 2.84 $ $ 2.90 ordinary share 1.81- diluted Weightedaverageordinary 232,886,942 210,953,579 215,308,768 205,224,221sharesoutstanding -dilutedHorizon Therapeutics plcCondensed Consolidated Balance Sheets(in thousands, except share data) As of December 31, December 31, 2020 2019ASSETSCURRENT ASSETS:Cash and cash $ 2,079,906 $ 1,076,287 equivalentsRestricted cash 3,573 3,752

Accounts 659,701 408,685 receivable, netInventories, 75,283 53,802 netPrepaidexpenses and 251,945 143,577 other currentassetsTotal current 3,070,408 1,686,103 assetsProperty and 189,037 30,159 equipment, netDevelopedtechnology and 1,782,962 1,702,628 otherintangibleassets, netGoodwill 413,669 413,669

Deferred tax 560,841 555,165 assets, netOther assets 55,699 48,310

$ 6,072,616 4,436,034 Total assets $

LIABILITIES ANDSHAREHOLDERS'EQUITYCURRENTLIABILITIES:Accounts $ 37,710 $ 21,514 payableAccrued 485,567 235,234 expensesAccrued trade 352,463 466,421 discounts andrebatesTotal current 875,740 723,169 liabilities LONG-TERMLIABILITIES:Exchangeable 351,533 Senior Notes, -netLong-term debt, 1,003,379 1,001,308 netDeferred tax 66,474 94,247 liabilities,netOther long-term 101,672 80,328 liabilitiesTotal long-term 1,171,525 1,527,416 liabilities COMMITMENTS AND CONTINGENCIESSHAREHOLDERS' EQUITY:Ordinaryshares, $0.0001nominal value;600,000,000sharesauthorized atDecember 31,2020 and December 31,2019;221,721,674 and 188,402,040shares issued at December 31,2020and December31, 2019,respectively, and 221,337,308and 188,017,674sharesoutstanding atDecember 31, 2020 and 22 19 December 31,2019,respectivelyTreasury stock,384,366ordinary shares (4,585 ) (4,585 )at December 31, 2020 andDecember 31,2019Additional 4,245,945 2,797,602 paid-in capitalAccumulatedother (145 ) (1,905 )comprehensivelossAccumulated (215,886 ) (605,682 )deficitTotal 4,025,351 2,185,449 shareholders' equityTotal liabilities and $ 6,072,616 $ 4,436,034 shareholders'equityHorizon Therapeutics plcCondensed Consolidated Statements of Cash Flows

(in thousands) Three Months Ended December 31, Twelve Months Ended December 31,

2020 2019 2020 2019

(Unaudited) CASH FLOWSFROM OPERATING ACTIVITIES:Net income $ 190,557 $ 592,769 $ 389,796 $ 573,020

Adjustments toreconcile netincome to net cash providedby operatingactivities:Depreciationand 69,545 59,821 279,451 237,157 amortizationexpenseEquity-settled 32,793 24,149 146,627 91,215 share-based compensationAcquiredin-process 30,000 77,517 research and - -developmentexpenseLoss on debt 31,856 58,835 extinguishment - -

Amortizationof debtdiscount and 615 5,533 12,640 22,602 deferredfinancingcosts(Gain)/Loss on (4,883 ) (4,883 ) 10,963 sale of assets -

Deferred (25,412 ) (573,840 ) (33,453 ) (565,537 )income taxesForeign exchange and 728 2 1,812 574 otheradjustmentsChanges inoperating assets andliabilities:Accounts 46,219 (11,996 ) (251,173 ) 56,166 receivableInventories 1,878 4,737 (21,451 ) (3,268 )

Prepaidexpenses and (31,562 ) (708 ) (114,788 ) (72,763 )other currentassetsAccounts (1,694 ) (5,385 ) 16,015 (8,723 )payableAccrued trade 29,560 61,832 (113,991 ) 8,591 discounts and rebatesAccrued 57,791 30,379 114,621 19,788 expensesDeferred (4,901 )revenues - - -

Othernon-current 13,682 4,087 25,092 2,613 assets andliabilitiesNet cashprovided by 409,817 191,380 555,688 426,332 operatingactivitiesCASH FLOWSFROM INVESTING ACTIVITIES:Purchases of (36,453 ) (6,532 ) (169,852 ) (17,857 )property and equipmentPayments for long-term (4,377 ) - (13,314 ) - investments,netProceeds from 5,400 5,400 6,000 sale of assets -

Payments for (262,305 ) acquisitions - - -

Change in escrow deposit - (6,000 ) 6,000 (6,000 )for propertypurchasePayment related to (30,000 ) - (30,000 ) - licenseagreementNet cash used (65,430 ) (12,532 ) (464,071 ) (17,857 )in investing activitiesCASH FLOWSFROM FINANCING ACTIVITIES:Net proceeds from issuance - - - 590,057 of seniornotesRepayment of (1,739 ) (814,420 )senior notes - -

Net proceedsfrom the (209 ) 919,786 326,793 issuance of -ordinarysharesRepayment of (418,026 ) (1,336,207 )term loans - -

Net proceeds 418,026 935,404 from term - -loansContingent consideration - - - 3,297 proceeds fromdivestitureProceeds fromthe issuanceof ordinary 8,189 5,849 16,168 11,317 shares in conjunctionwith ESPPprogramProceeds fromthe issuanceof ordinaryshares in 2,870 8,646 36,869 24,882 connectionwith stockoptionexercisesPayment ofemployeewithholding (6,753 ) (2,109 ) (66,505 ) (31,569 )taxes relatingto share-basedawardsNet cashprovided by 4,097 12,386 904,579 (290,446 )(used in) financingactivities Effect offoreignexchange ratechanges on 6,019 1,095 7,244 (107 )cash, cashequivalentsand restrictedcash Net increasein cash, cash 354,503 192,329 1,003,440 117,922 equivalents and restrictedcashCash, cashequivalentsand restricted 1,728,976 887,710 1,080,039 962,117 cash,beginning ofthe period^(1)Cash, cashequivalents $ 2,083,479 $ 1,080,039 $ 2,083,479 $ 1,080,039 and restricted cash, end ofthe period^(1) (1) Amounts include restricted cash balance in accordance with ASU No. 2016-18.Cash and cash equivalents excluding restricted cash are shown on the balancesheet.

Horizon Therapeutics plcGAAP to Non-GAAP ReconciliationsNet Income and Earnings Per Share (Unaudited)(in thousands, except share and per share data) Three Months Ended December 31, Twelve Months Ended December 31,

2020 2019 2020 2019

GAAP net income $ 190,557 $ 592,769 $ 389,796 $ 573,020

Non-GAAP adjustments:Acquisition/ 1,900 49,196 3,556 divestiture-related 942costsRestructuring and (141 ) (141 ) realignment costs 204 237

Amortization and step-up:Intangible 64,471 57,662 255,148 230,424 amortization expenseInventory step-up expense - - - 89

Amortization of debt discount and 615 5,533 12,640 22,602 deferred financingcostsImpairment of 1,713 long-lived assets 641 - -

(Gain)/Loss on sale (4,883 ) (4,883 ) 10,963 of assets -

Share-based 32,793 24,149 146,627 91,215 compensationDepreciation 5,074 2,159 24,303 6,733

Litigation 1,000 settlements - - -

Upfront, progressand milestone payments related tolicense and 30,000 33,000 9,073 collaboration -agreementsFees related to 2,292 refinancing - 855 54activitiesLoss on debt 31,856 58,835 extinguishment - -

Drug substance harmonization costs 59 63 542 457

Charges relating to discontinuation of - (145 ) - 1,076 Friedreich's ataxiaprogramTotal of pre-tax 130,529 91,422 550,055 438,552 non-GAAP adjustmentsIncome tax effect (22,631 ) (14,277 ) (102,753 ) (66,568 )of pre-tax non-GAAP adjustmentsOther non-GAAP (553,334 ) 20,541 (554,786 )income tax -adjustmentsTotal of non-GAAP 107,898 (476,189 ) 467,843 (182,802 )adjustmentsNon-GAAP Net Income $ 298,455 $ 116,580 $ 857,639 $ 390,218

Non-GAAP Earnings Per Share: Weighted average 220,929,626 187,421,561 203,967,246 182,930,109 ordinary shares - Basic Non-GAAP Earnings Per Share - Basic:GAAP earnings per $ 0.86 $ 3.16 $ 1.91 $ 3.13 share - Basic Non-GAAP 0.49 (2.54 ) 2.29 (1.00 )adjustmentsNon-GAAP earnings $ 1.35 $ 0.62 $ 4.20 $ 2.13 per share - Basic Non-GAAP Net Income $ 298,455 $ 116,580 $ 857,639 $ 390,218

Effect of assumed exchange of - 1,875 3,789 7,500 Exchangeable SeniorNotes, net of taxNumerator - $ 298,455 $ 118,455 $ 861,428 $ 397,718 non-GAAP Net Income Weighted averageordinary shares - DilutedWeighted average 220,929,626 187,421,561 203,967,246 182,930,109 ordinary shares - BasicOrdinary share 11,957,316 23,532,018 18,203,897 22,294,112 equivalentsDenominator -weighted average 232,886,942 210,953,579 222,171,143 205,224,221 ordinary shares -Diluted Non-GAAP Earnings Per Share - DilutedGAAP earnings per $ 0.82 $ 2.84 $ 1.81 $ 2.90 share - Diluted Non-GAAP 0.46 (2.28 ) 2.07 (0.96 )adjustmentsDiluted earnings per share effect of - - - - ordinary shareequivalentsNon-GAAP earnings $ 1.28 $ 0.56 $ 3.88 $ 1.94 per share - DilutedHorizon Therapeutics plcGAAP to Non-GAAP ReconciliationsEBITDA (Unaudited)(in thousands) Three Months Ended December 31, Twelve Months Ended December 31,

2020 2019 2020 2019

GAAP net income $ 190,557 $ 592,769 $ 389,796 $ 573,020

Depreciation 5,074 2,159 24,303 6,733

Amortization and step-up:Intangible 64,471 57,662 255,148 230,424 amortization expenseInventory step-up expense - - - 89

Interest expense,net (including amortization ofdebt discount and 11,516 17,098 59,616 87,089 deferred financing costs)Expense (Benefit) 38,992 (555,885 ) 11,849 (593,244 )for income taxesEBITDA $ 310,610 $ 113,803 $ 740,712 $ 304,111

Other non-GAAP adjustments:Acquisition/ 1,900 49,196 3,556 divestiture-related 942costsRestructuring and (141 ) (141 ) realignment costs 204 237

Impairment of 1,713 long-lived assets 641 - -

(Gain)/Loss on sale (4,883 ) (4,883 ) 10,963 of assets -

Share-based 32,793 24,149 146,627 91,215 compensationLitigation 1,000 settlements - - -

Upfront, progressand milestone payments related tolicense and 30,000 33,000 9,073 collaboration -agreementsFees related to 2,292 refinancing - 855 54activitiesLoss on debt 31,856 58,835 extinguishment - -

Drug substance harmonization costs 59 63 542 457

Charges relating to discontinuation of - (145 ) - 1,076 Friedreich's ataxiaprogramTotal of other 60,369 26,068 257,964 178,704 non-GAAP adjustmentsAdjusted EBITDA $ 370,979 $ 139,871 $ 998,676 $ 482,815

Horizon Therapeutics plcGAAP to Non-GAAP ReconciliationsOperating Income (Unaudited)(in thousands) Three Months Ended December 31, Twelve Months Ended December 31,

2020 2019 2020 2019

GAAP operating $ 240,071 $ 54,675 $ 490,026 $ 126,611incomeNon-GAAP adjustments:Acquisition/ 1,816 (200 ) 49,232 1,032divestiture-related costsRestructuring and (141 ) (141 ) realignment costs 204 237

Amortization and step-up:Intangible 64,471 57,662 255,148 230,424amortization expenseInventory step-up expense - - - 89

Impairment of 1,713 long-lived assets 641 - -

(Gain)/Loss on sale (4,883 ) (4,883 ) 10,963of assets -

Share-based 32,793 24,149 146,627 91,215compensationDepreciation 5,074 2,159 24,303 6,733

Litigation 1,000settlements - - -

Upfront, progressand milestone payments related tolicense and 30,000 33,000 9,073collaboration -agreementsFees related to 2,292refinancing - 855 54activitiesDrug substance harmonization costs 59 63 542 457

Charges relating to discontinuation of - (145 ) - 1,076Friedreich's ataxiaprogramTotal of non-GAAP 129,830 84,747 505,595 354,591adjustmentsNon-GAAP operating $ 369,901 $ 139,422 $ 995,621 $ 481,202income Orphan segment 302,975 83,252 783,560 263,347operating incomeInflammation 66,926 56,170 212,061 217,855segment operating incomeTotal segment $ 369,901 $ 139,422 $ 995,621 $ 481,202operating income Foreign exchange (603 ) (297 ) (loss)/gain 58 33

1,681 3,352 1,580 Other income, net 391

Adjusted EBITDA $ 370,979 $ 139,871 $ 998,676 $ 482,815

Horizon Therapeutics plcGAAP to Non-GAAP ReconciliationsGross Profit and Operating Cash Flow (Unaudited)(in thousands, except percentages) Three Months Ended December 31, Twelve Months Ended December 31, 2020 2019 2020 2019

Non-GAAP Gross Profit: GAAP gross profit $ 583,025 $ 268,624 $ 1,667,734 $ 937,854

Non-GAAP gross profit adjustments:Acquisition/ - - 1,115 divestiture-related -costsIntangible 64,267 57,458 254,337 229,614 amortization expenseInventory step-up - - expense - 89

Share-based 1,660 927 7,203 3,818 compensation (96 ) 155 339 Depreciation 630

Drug substance 59 542 harmonization costs 63 457

Charges relating todiscontinuation of - (145 ) - 1,076 Friedreich's ataxiaprogramTotal of Non-GAAP 65,890 58,458 262,421 236,799 adjustmentsNon-GAAP gross $ 648,915 $ 327,082 $ 1,930,155 $ 1,174,653 profit GAAP gross profit % 78.2 % 73.9 % 75.8 % 72.1 %

Non-GAAP gross 87.1 % 90.0 % 87.7 % 90.4 %profit % GAAP cash provided $ 409,817 $ 191,380 $ 555,688 $ 426,332 by operating activitiesCash payments for acquisition/ 1,084 - 1,164 583 divestiture-relatedcostsCash payments for 200 189 3,464 restructuring and -realignment costsCash payments for 1,000 litigation - - -settlementsCash payments forupfront, progressand milestone 9,073 payments related to - - -license andcollaborationagreementCash payments drug 252 542 1,052 substance 67harmonization costsCash payments for discontinuation of - - - 2,589 Friedreich's ataxiaprogramCash payments relating to - 369 73 2,287 refinancingactivitiesNon-GAAP operating $ 411,153 $ 192,016 $ 557,656 $ 446,380 cash flowHorizon Therapeutics plc

GAAP to Non-GAAP Tax Rate Reconciliation (Unaudited)

(in millions, except percentages and per share amounts)

Q4 2020 Pre-tax Net Income Tax Net Income Diluted Earnings

(Loss) Income (Benefit) Expense Tax Rate (Loss) (Loss) Per Share

As reported $ 229.5 $ 17.0 % $ $ - GAAP 39.0 190.6 0.82

Non-GAAP adjustments 130.5 22.6 107.9

$ 360.1 $ 17.1 % $ $ Non-GAAP 61.6 298.5 1.28

Q4 2019 Pre-tax Net Income Tax Net Income Diluted Earnings

(Loss) Income (Benefit) Expense Tax Rate (Loss) (Loss) Per Share

As reported $ $ (555.9 ) (1507.0 ) $ $ - GAAP 36.9 % 592.8 2.84

Non-GAAP )adjustments 91.4 567.6 (476.2

$ 128.3 $ 9.1 % $ $ Non-GAAP 11.7 116.6 0.56

FY 2020 Pre-tax Net Income Tax Net Income Diluted Earnings

(Loss) Income (Benefit) Expense Tax Rate (Loss) (Loss) Per Share

As reported $ 401.6 $ 3.0 % $ $ - GAAP 11.8 389.8 1.81

Non-GAAP adjustments 550.1 82.2 467.8

$ 951.7 $ 9.9 % $ $ Non-GAAP 94.1 857.6 3.88

FY 2019 Pre-tax Net Income Tax Net Income Diluted Earnings

(Loss) Income (Benefit) Expense Tax Rate (Loss) (Loss) Per Share

As reported $ (20.2 ) $ (593.2 ) 2933.0 % $ $ - GAAP 573.0 2.90

Non-GAAP )adjustments 438.6 621.4 (182.8

$ 418.3 $ 6.7 % $ $ Non-GAAP 28.2 390.2 1.94

Horizon Therapeutics plc

Certain Income Statement Line Items - Non-GAAP Adjusted

For the Three Months Ended Dec. 31, 2020 (Unaudited)

(in thousands)

Income Tax Research & Selling, General Loss/(Gain) on Interest Other Benefit COGS Development & Administrative Sale of Assets Expense Expense (Expense) GAAP as reported $ (162,289 ) $ (70,881 ) $ (276,956 ) $ 4,883 $ (11,516 ) $ 1,597 $ (38,992 )

Non-GAAPAdjustments (in thousands): Acquisition/ (141 ) 1,957 divestiture-related - - - 84 -costs^(1)Restructuring and (141 ) realignment costs^ - - - - - -(2)Amortization and step-up:Intangible 64,267 204 amortization - - - - -expense^(3)Amortization of debt discount and - - - - 615 - - deferred financingcosts^(4)Impairment of long 641 lived assets^(5) - - - - - -

(Gain)/Loss on sale (4,883 ) of assets^(6) - - - - - -

Share-based 1,660 2,592 28,541 compensation^(7) - - - -

) 5,138 Depreciation^(8) (96 32 - - - -

Upfront, progressand milestone payments related to - 30,000 - - - - - license andcollaborationagreements^(9)Drug substance harmonization costs 59 - - - - - -^(10)Income tax effect (22,631 )on pre-tax non-GAAP - - - - - - adjustments^(11)Total of non-GAAP 65,890 32,483 36,340 (4,883 ) (22,631 )adjustments 615 84

Non-GAAP $ (96,399 ) $ (38,398 ) $ (240,616 ) $ - $ (10,901 ) $ 1,681 $ (61,623 )

Horizon Therapeutics plc

Certain Income Statement Line Items - Non-GAAP Adjusted

For the Three Months Ended December 31, 2019

(Unaudited)

Income Tax Research & Selling, General Interest Other Benefit COGS Development & Administrative Expense Income, net (Expense) GAAP as reported $ (94,921 ) $ (28,558 ) $ (185,391 ) $ (17,098 ) $ (751 ) $ 555,885

Non-GAAPAdjustments (in thousands): Acquisition/ (184 ) (19 ) 1,145 divestiture-related - - - costs^(1)Restructuring and 204 realignment costs^ - - - - - (2)Amortization and step-up:Intangible 57,458 204 amortization - - - - expense^(3)Amortization of debt discount and - - - 5,533 - - deferred financingcosts^(4)Share-based 2,186 21,036 compensation^(7) 927 - - -

1,991 Depreciation^(8) 155 13 - - -

Fees related to 855 refinancing - - - - - activities ^(12)Drug substance harmonization costs 63 - - - - - ^(10)Charges relating to discontinuation of (145 ) - - - - - Friedreich's ataxiaprogram^(13)Income tax effect (14,277 )on pre-tax non-GAAP - - - - - adjustments^(11)Other non-GAAP (553,334 )income tax - - - - - adjustments^(14)Total of non-GAAP 58,458 2,015 24,271 5,533 1,145 (567,611 ) adjustments Non-GAAP $ (36,463 ) $ (26,543 ) $ (161,120 ) $ (11,565 ) $ 394 $ (11,726 )

Horizon Therapeutics plc

Certain Income Statement Line Items - Non-GAAP Adjusted

For the Twelve Months Ended Dec. 31, 2020 (Unaudited)

(in thousands)

Income Tax Research & Selling, General Loss/(Gain) on Interest Other Loss on Debt Benefit COGS Development & Administrative Sale of Assets Expense Expense Extinguishment (Expense) GAAP as reported $ (532,695 ) $ (209,364 ) $ (973,227 ) $ 4,883 $ (59,616 ) $ 3,388 $ (31,856 ) $ (11,849 )

Non-GAAPAdjustments (in thousands): Acquisition/ 47,223 2,008 ) divestiture-related - - - (35 - -costs^(1)Restructuring and (141 ) realignment costs^ - - - - - - -(2)Amortization and step-up:Intangible 254,337 amortization - 811 - - - - -expense^(3)Amortization of debt discount and - - - - 12,640 - - - deferred financingcosts^(4)Impairment of long 1,713 lived assets^(5) - - - - - - -

(Gain)/Loss on sale (4,883 ) of assets^(6) - - - - - - -

Share-based 7,203 13,973 125,451 compensation^(7) - - - - -

23,860 Depreciation^(8) 339 104 - - - - -

Loss on debt 31,856 extinguishment^(15) - - - - - - -

Upfront, progressand milestone payments related to - 33,000 - - - - - - license andcollaborationagreements^(9)Fees related to refinancing - - 54 - - - - -activities ^(12)Drug substance harmonization costs 542 - - - - - - -^(10)Income tax effect (102,753 )on pre-tax non-GAAP - - - - - - - adjustments^(11)Other non-GAAP 20,541 income tax - - - - - - - adjustments^(14)Total of non-GAAP 262,421 94,300 153,756 (4,883 ) 12,640 ) 31,856 (82,212 )adjustments (35

Non-GAAP $ (270,274 ) $ (115,064 ) $ (819,471 ) $ - $ (46,976 ) $ 3,353 $ - $ (94,061 )

Horizon Therapeutics plc

Certain Income Statement Line Items - Non-GAAP Adjusted

For the Twelve Months Ended December 31, 2019

(Unaudited)

Income Tax Research & Selling, General Loss on Debt Loss/(Gain) on Interest Other Benefit COGS Development & Administrative Extinguishment Sale of Assets Expense Income (Expense) GAAP as reported $ (362,175 ) $ (103,169 ) $ (697,111 ) $ (58,835 ) $ (10,963 ) $ (87,089 ) (944 ) $ 593,244

Non-GAAPAdjustments (in thousands): Acquisition/ 1,115 (184 ) 2,524 divestiture-related 101 - - - -costs^(1)Restructuring and realignment costs^ - - 237 - - - - -(2)Amortization and step-up:Intangible 229,614 amortization - 810 - - - - -expense^(3)Inventory step-up expense 89 - - - - - - -

Amortization of debt discount and - - - - - 22,602 - deferred financingcosts^(4)Impairment of long lived assets^(5) - - - - - - - -

(Gain)/Loss on sale 10,963 of assets^(6) - - - - - - -

Share-based 3,818 9,117 78,280 compensation^(7) - - - - -

6,090 Depreciation^(8) 630 13 - - - - -

Litigation 1,000 settlements^(16) - - - - - - -

Upfront, progressand milestone payments related to - 9,073 - - - - - - license andcollaborationagreements^(9)Fees related to 2,292 refinancing - - - - - - -activities ^(12)Loss on debt 58,835 extinguishment^(15) - - - - - - -

Drug substance harmonization costs 457 - - - - - - -^(10)Charges relating to discontinuation of 1,076 - - - - - - - Friedreich's ataxiaprogram^(13)Income tax effect (66,568 )on pre-tax non-GAAP - - - - - - - adjustments^(11)Other non-GAAP (554,786 )income tax - - - - - - - adjustments^(14)Total of non-GAAP 236,799 18,019 88,810 58,835 10,963 22,602 2,524 (621,354 )adjustments $ (125,376 ) $ (85,150 ) $ (608,301 ) $ (64,487 ) $ 1,580 $ (28,110 )Non-GAAP - -

NOTES FOR CERTAIN INCOME STATEMENT LINE ITEMS - NON-GAAP

* Represents expenses, including legal and consulting fees, incurred in connection with our acquisitions and divestitures. Costs recovered from subleases of acquired facilities and reimbursed expenses incurred under transition arrangements for divestitures are also reflected in this line item. In addition, the year ended December 31, 2020 amounts include the Curzion acquisition payment of $45.0 million, which was recorded as a research and development expense. * Represents expenses, including severance costs and consulting fees, related to restructuring and realignment activities. * Intangible amortization expenses are associated with our intellectual property rights, developed technology and customer relationships related to TEPEZZA, KRYSTEXXA, RAVICTI, PROCYSBI, ACTIMMUNE, BUPHENYL, PENNSAID 2%, RAYOS, VIMOVO and MIGERGOT. * Represents amortization of debt discount and deferred financing costs associated with our debt. * During the year ended December 31, 2020, we recorded an impairment charge of $1.7 million related to the Novato, California office lease, which was obtained through an acquisition. * During the year ended December 31, 2020, we completed the sale of rights to RAVICTI and BUPHENYL in Japan for cash proceeds of $5.4 million, and we recorded a gain of $4.9 million on the sale. During the year ended December 31, 2019, we recorded a loss of $11.0 million on the sale of our rights to MIGERGOT. * Represents share-based compensation expense associated with our stock option, restricted stock unit and performance stock unit grants to our employees and non-employee directors, and our employee share purchase plan. * Represents depreciation expense related to our property, equipment, software and leasehold improvements. * During the year ended December 31, 2020, we incurred $30.0 million of an upfront cash payment related to a license agreement entered into with Halozyme. The upfront cash payment was paid in December 2020. In addition, we recognized a $3.0 million progress payment in relation to the collaboration agreement with HemoShear, which was paid in July 2020. During the year ended December 31, 2019, we recorded upfront, progress and milestone payments related to license and collaboration agreements of $9.1 million which was composed of a $3.0 million milestone payment to Roche relating to the TEPEZZA BLA submission to the FDA during the third quarter of 2019, and an upfront cash payment of $2.0 million and a progress payment of $4.0 million in relation to the collaboration agreement with HemoShear. * During the year ended December 31, 2016, we entered into a definitive agreement to acquire certain rights to interferon gamma-1b, marketed as IMUKIN in an estimated thirty countries primarily in Europe and the Middle East, or the IMUKIN purchase agreement. We already owned the rights to interferon gamma-1b marketed as ACTIMMUNE in the United States, Canada and Japan. In connection with the IMUKIN purchase agreement, we also committed to pay our contract manufacturer certain amounts related to the harmonization of the manufacturing processes for ACTIMMUNE and IMUKIN drug substance, or the harmonization program. At the time we entered into the IMUKIN purchase agreement and the harmonization program commitment was made, we had anticipated achieving certain benefits should the Phase 3 clinical trial evaluating ACTIMMUNE for the treatment of Friedreich's ataxia, be successful. If the study had been successful and if U.S. marketing approval had subsequently been obtained, we had forecasted significant increases in demand for the medicine and the harmonization program would have resulted in significant benefits for us. Following our discontinuation of the Friedreich's ataxia program, we determined that certain assets, including an upfront payment related to the IMUKIN purchase agreement, were impaired, and the costs under the harmonization program would no longer have benefit to us and should be expensed as incurred. * Income tax adjustments on pre-tax non-GAAP adjustments represent the estimated income tax impact of each pre-tax non-GAAP adjustment based on the statutory income tax rate of the applicable jurisdictions for each non-GAAP adjustment. * Represents arrangement and other fees relating to our refinancing activities. * Represents expenses incurred relating to discontinuation of the Friedreich's ataxia program and a reduction to previous charges recorded. * During the year ended December 31, 2020, following the publication by the United States Department of Treasury and the Internal Revenue Service of the Anti-Hybrid Rules on April 8, 2020, we recorded a write-off of a deferred tax asset related to certain interest expense accrued to a foreign related party during the year ended December 31, 2019 and recognized a corresponding one-time tax provision, resulting in a non-GAAP tax adjustment of $15.2 million. We also recognized a U.S. federal tax liability on U.S. taxable income generated from an intra-company transfer of intellectual property from a U.S. subsidiary to an Irish subsidiary, which was partially offset by the recognition of a deferred tax asset in the Irish subsidiary, resulting in a non-GAAP tax adjustment of $5.3 million. Other non-GAAP income tax adjustments during the year ended December 31, 2019, primarily reflect a tax benefit of $553.3 million resulting from an intra-company transfer of intellectual property assets to an Irish subsidiary. * During the year ended December 31, 2020, we recorded a loss on debt extinguishment of $31.9 million in the condensed consolidated statements of comprehensive income (loss), which reflects the extinguishment of our Exchangeable Senior Notes. During the year ended December 31, 2019, we recorded a loss on debt extinguishment of $58.8 million in the condensed consolidated statements of comprehensive income (loss), which reflected the early redemption premiums and the write-off of the deferred financing fees and debt discount fees related to the prepayment of $775.0 million of our 2023 Senior Notes and 2024 Senior Notes and the write-off of the deferred financing fees and debt discount fees related to the $400.0 million of term loan repayments. * We recorded $1.0 million of expense during the year ended December 31, 2019 for litigation settlements. View source version on businesswire.com: https://www.businesswire.com/news/home/20210224005532/en/

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CONTACT: Ireland Media: Ray Gordon Gordon MRM ray@gordonmrm.ie