^Ad hoc announcement pursuant to Art. 53 LR

* Idorsia receives a positive opinion from the Committee for Medicinal

Products for Human Use for JERAYGO(TM) (aprocitentan) as the first and only

endothelin receptor antagonist for the treatment of resistant hypertension

in adult patients in combination with at least three antihypertensive

medicinal products.

* A CHMP positive opinion is one of the final steps before marketing

authorization can be granted by the European Commission - a final decision

is expected in approximately two months.

Allschwil, Switzerland - April 26, 2024

Idorsia Ltd (SIX: IDIA) announced today that the Committee for Medicinal

Products for Human Use (CHMP), the scientific committee of the European

Medicines Agency (EMA), adopted a positive opinion for the use of JERAYGO(TM)

(aprocitentan) for the treatment of resistant hypertension in adult patients in

combination with at least three antihypertensive medicinal products. The CHMP

has adopted a positive opinion for the use of 12.5 mg JERAYGO orally once daily.

The dose can be increased to 25 mg once daily for patients tolerating the 12.5

mg dose and in need of tighter blood pressure (BP) control.

Detailed recommendations for the use of JERAYGO will be described in the summary

of product characteristics (SmPC), which will be published in the European

public assessment report (EPAR) and made available in all official European

Union languages after the marketing authorization has been granted by the

European Commission, expected in approximately two months.

Hypertension is one of the leading causes of cardiovascular disease worldwide,

impacting an estimated 1.3 billion people globally.(1) Approximately 10% of

these people have uncontrolled BP, despite receiving at least three

antihypertensive medications from different classes, at optimal doses and they

are categorized in hypertension guidelines(2,3) as having resistant

hypertension. Compared with adults whose hypertension is well controlled, adult

with uncontrolled hypertension have greater risk of heart attack, heart failure,

stroke, end-stage renal disease and death.(4)

Jean-Paul Clozel, MD and Chief Executive Officer of Idorsia commented:

"Uncontrolled hypertension, particularly resistant hypertension, where blood

pressure remains uncontrolled despite the use of multiple antihypertensive

therapies, affects millions of Europeans and is a major public health issue

leading to a high risk of heart attack, heart failure, stroke and renal disease,

not to mention the increased risk of death. Idorsia has tackled this need by

developing aprocitentan, or JERAYGO, the brand name in Europe, an endothelin

receptor antagonist discovered by our team and optimized for the treatment of

resistant hypertension. As a result of our efforts, physicians and patients in

Europe are one step closer to having a new oral antihypertensive therapy - the

first in almost 40 years - that is working via a new therapeutic pathway."

The positive CHMP opinion is supported by a comprehensive clinical and non-

clinical development program. Aprocitentan was evaluated as a monotherapy in a

Phase 2 study in patients with hypertension,(11) and as an add-on therapy in a

Phase 3 study called PRECISION in patients with confirmed resistant

hypertension.(12) In the Phase 3 registration study, PRECISION, aprocitentan

showed statistically significant and clinically meaningful reduction in blood

pressure (BP) which was maintained for up to 48 weeks when added to a

combination of background antihypertensive therapies in patients with resistant

hypertension. In PRECISION, aprocitentan was generally well tolerated with no

major safety concerns. The most frequent adverse event with aprocitentan wa

mild-to-moderate edema/fluid retention.

The team at Idorsia has been working on the research and development of

endothelin receptor antagonists for more than 30 years, successfully bringing

three other molecules from this class to patients in different indications.

Endothelin (ET)-1, via its receptors (ET(A) and ET(B)), mediates a variety of

effects such as vasoconstriction, fibrosis, cell proliferation, inflammation,

aldosterone production(7) and is upregulated in hypertension. Aprocitentan is a

dual ERA that inhibits the binding of ET-1 to ET(A) and ET(B) receptors and

hence the effects mediated by these receptors.(5) The effects of ET-1 bear many

similarities with the pathophysiology of hypertension,(6)(,8) and the resistance

to other antihypertensive drugs in some patients (often with risk factors such

as obesity, sleep apnea, older age, kidney failure, type 2 diabetes, and African

Americans), can be explained by an endothelin-dependent hypertension(8). This i

now confirmed by the efficacy of aprocitentan in the PRECISION study.

About the Phase 3 PRECISION study (NCT03541174

(https://classic.clinicaltrials.gov/ct2/show/NCT03541174))(12)

PRECISION was a multicenter, blinded, randomized, parallel-group, Phase 3 study,

which was performed in hospitals or research centers in Europe, North America,

Asia, and Australia. Patients were eligible for randomization if their sitting

systolic blood pressure (SBP) was 140 mm Hg or higher despite taking

standardized background therapy consisting of three antihypertensive drugs,

including a diuretic. The study consisted of three sequential parts: Part 1 wa

the 4-week double-blind, randomized, and placebo-controlled part, in which 730

patients were randomized to aprocitentan 12.5 mg (n=243), aprocitentan 25 mg

(n=243), or placebo (n=244) in a 1:1:1 ratio; Part 2 was a 32-week single

(patient)-blind part, in which all patients received aprocitentan 25 mg (n=704);

and Part 3 was a 12-week double-blind, randomized, and placebo-controlled

withdrawal part, in which patients were re-randomized to aprocitentan 25 mg

(n=307) or placebo (n=307) in a 1:1 ratio. The primary and key secondary

endpoints were changes in unattended office SBP from baseline to week 4 and from

withdrawal baseline to week 40, respectively. Secondary endpoints included 24-h

ambulatory blood pressure changes.

At baseline, 69.2% of patients were obese or severely obese, 54.1% had diabetes,

22.2% had stage 3-4 chronic kidney disease and 19.6% had congestive heart

failure. At screening, 63% of all patients who were randomly assigned were

prescribed four or more antihypertensive drugs.

Key PRECISION findings(13)

The least square mean change in office SBP at 4 weeks was -15.3 mmHg for

aprocitentan 12.5 mg,

-15.2 mmHg for 25 mg, and -11.5 mmHg for placebo, for a difference versu

placebo of -3.8 mmHg (p=0.0042) and -3.7 mmHg (p=0.0046), respectively (the

primary endpoint). Office diastolic blood pressure (DBP) also decreased with

both aprocitentan doses compared to placebo (-3.9 mmHg for the 12.5 mg dose and

-4.5 mmHg for the 25 mg dose). Office SBP and DBP were maintained during Part 2

in patients previously receiving aprocitentan and decreased within the first 2

weeks of Part 2 before stabilizing in those previously receiving placebo. In

Part 3, office SBP after 4 weeks of withdrawal (week 40) (the key secondary

endpoint) increased significantly with placebo compared to aprocitentan (5.8

mmHg; p= 75 years), sex, race (including patients with Black or African

American origin), BMI, baseline urine albumin-to-creatinine ratio (UACR),

baseline estimated Glomerular Filtration Rate (eGFR) and medical history of

diabetes, and was consistent with the effect in the overall population.

Treatment-emergent adverse events (TEAEs) during the 4-week double-blind study

period (Part 1) were reported in 27.6% and 36.7% of the patients treated with

12.5 and 25 mg aprocitentan, respectively, versus 19.4% in the placebo group.

The most frequent adverse event with aprocitentan was mild-to-moderate

edema/fluid retention leading to discontinuation in seven patients during the

study. Edema/fluid retention was reported more frequently with aprocitentan than

with placebo in a dose-dependent fashion (9.1%, 18.4%, and 2.1% for patient

receiving aprocitentan 12.5 mg, 25 mg and placebo, during Part 1, respectively;

18.2% for patients receiving aprocitentan 25 mg during Part 2; and 2.6% and

1.3% for patients on aprocitentan 25 mg and placebo, during Part 3,

respectively).

Regulatory status of aprocitentan

The positive opinion recommending JERAYGO, is a scientific recommendation issued

by the EMA's CHMP, which is sent to the European Commission (EC) for the

adoption of a decision on an EU-wide marketing authorization. An EC marketing

authorization through the centralized procedure is valid in all European Union

Member States, as well as the European Economic Area countries Iceland,

Liechtenstein and Norway, and Northern Ireland under the Northern Ireland

Protocol.

In March, TRYVIO(TM) (aprocitentan) was approved by the US Food and Drug

Administration (FDA).

Notes to the editor

Reference

1. NCD Risk Factor Collaboration (NCD-RisC). Worldwide trends in hypertension

prevalence and progress in treatment and control from 1990 to 2019: a

pooled analysis of 1201 population-representative studies with 104 million

participants. Lancet 2021; 398:957-80.

2. Noubiap JJ, et al. Global prevalence of resistant hypertension: a meta-

analysis of data from 3·2 million patients. Heart 2019; 105: 98-105.

3. Williams B, et al. 2018 ESC/ESH guidelines for the management of arterial

hypertension. Eur Heart J 2018; 39: 3021-104.

4. Daugherty SL, et al. Incidence and prognosis of resistant hypertension in

hypertensive patients. Circulation. 2012 Apr 3;125(13):1635-42.

5. Trensz F, et al. Pharmacological characterization of aprocitentan, a dual

endothelin receptor antagonist, alone and in combination with blockers of

the renin angiotensin system, in two models of experimental hypertension. J

Pharmacol Exp Ther. 2019 Mar; 368(3):462-473.

6. Iglarz M, et al. At the heart of tissue: endothelin system and end-organ

damage. Clin Sci 2010; 119:453-63.

7. Rossi GP, et al. Endothelin-1 stimulates steroid secretion of human

adrenocortical cells ex vivo via both ETA and ETB receptor subtypes. J Clin

Endocrinol Metab. 1997, 82: 3445-3449

8. Clozel M. Aprocitentan and the endothelin system in resistant hypertension.

Can J Physiol Pharmacol 2022; 100:573-83.

9. Whelton P.K., et al. 2018. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/

ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and

management of high blood pressure in adults: a report of the American

College of Cardiology/American Heart Association Task Force on clinical

practice guidelines. Hypertension, 71: e13-e115.

10. Williams B, et al. 2018 ESC/ESH guidelines for the management of arterial

hypertension. Eur Heart J 2018; 39: 3021-104.

11. Verweij P. et al. Randomized Dose-Response Study of the New Dual Endothelin

Receptor Antagonist Aprocitentan in Hypertension. Hypertension.

2020;75:956-965

12. Danaietash P et al. Identifying and treating resistant hypertension in

PRECISION: A randomized long-term clinical trial with aprocitentan. J Clin

Hypertension 2022 Jul;24(7):804-813.

13. Schlaich MP, et al. A randomized controlled trial of the dual endothelin

antagonist aprocitentan for resistant hypertension. The Lancet, 2022; Dec

3;400(10367):1927-1937.

About Idorsia

Idorsia Ltd is reaching out for more - We have more ideas, we see more

opportunities and we want to help more patients. In order to achieve this, we

will develop Idorsia into a leading biopharmaceutical company, with a strong

scientific core.

Headquartered near Basel, Switzerland - a European biotech-hub - Idorsia i

specialized in the discovery, development and commercialization of small

molecules to transform the horizon of therapeutic options. Idorsia has a 25-year

heritage of drug discovery, a broad portfolio of innovative drugs in the

pipeline, an experienced team of professionals covering all disciplines from

bench to bedside, and commercial operations in Europe and North America - the

ideal constellation for bringing innovative medicines to patients.

Idorsia was listed on the SIX Swiss Exchange (ticker symbol: IDIA) in June 2017

and has over 750 highly qualified specialists dedicated to realizing our

ambitious targets.

For further information, please contact

Investors & Media

Andrew C. Wei

Senior Vice President, Head of Investor Relations & Corporate Communication

Idorsia Pharmaceuticals Ltd, Hegenheimermattweg 91, CH-4123 Allschwil

+41 58 844 10 10

investor.relations@idorsia.com ? media.relations@idorsia.com ? www.idorsia.com

The above information contains certain "forward-looking statements", relating to

the company's business, which can be identified by the use of forward-looking

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"anticipates" or similar expressions, or by discussions of strategy, plans or

intentions. Such statements include descriptions of the company's investment and

research and development programs and anticipated expenditures in connection

therewith, descriptions of new products expected to be introduced by the company

and anticipated customer demand for such products and products in the company'

existing portfolio. Such statements reflect the current views of the company

with respect to future events and are subject to certain risks, uncertaintie

and assumptions. Many factors could cause the actual results, performance or

achievements of the company to be materially different from any future results,

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looking statements. Should one or more of these risks or uncertaintie

materialize, or should underlying assumptions prove incorrect, actual result

may vary materially from those described herein as anticipated, believed,

estimated or expected.

°