^Ad hoc announcement pursuant to Art. 53 LR

* Jean-Paul Clozel to retire as CEO and stand for election as Chairman of the

Board of Directors

* Mathieu Simon to stand for re-election to the Board - taking on the role of

Vice-Chairman and Lead Independent Director

* André C. Muller, current CFO of Idorsia, to take over the role of CEO as of

June 13, 2024

Allschwil, Switzerland - May 21, 2024

Idorsia Ltd (SIX: IDIA) today announced changes to the Idorsia Executive

Committee (IEC) and will propose changes in membership of the Board of Directors

at the upcoming Annual General Meeting of shareholders (AGM), to be held on June

13, 2024.

Jean-Paul Clozel, 69, has decided to retire from his role as Chief Executive

Officer (CEO) of Idorsia and stand for election as Chairman of the Board of

Directors at this year's AGM. Jean-Paul has served as CEO of Idorsia since its

foundation - the result of demerging the drug discovery and early clinical

pipeline of Actelion, as part of the USD 30 billion acquisition. Jean-Paul had

previously co-founded Actelion in 1997 and went on to lead the company as CEO in

2000 when the company became publicly traded.

Jean-Paul Clozel, MD and CEO of Idorsia, commented:

"It has been an absolute privilege to serve as CEO of Actelion and Idorsia for

the past 24 years. I can think of no greater endeavor than discovering new

medicines that help patients lead better lives. I've been very fortunate to work

alongside some amazing people from all disciplines and together, we have

achieved more than I could have ever imagined when I started out in my research

career. The time is right for me to retire from the day-to-day running of

Idorsia and hand the reins over to a younger generation to lead the company

through the next phase of growth. Having devoted so much energy to Idorsia, I

want to stay engaged and support the company to realize its potential, hence me

standing for election as Chairman. I'm confident that Mathieu and I will form a

strong partnership in leading the Board. I will also be able to devote more time

to science which has always been my passion."

From June 13, 2024, André C. Muller will take on the position of CEO. André has

served as the Chief Financial Officer (CFO) of Idorsia since its foundation and

has taken the lead in the company's Business Development initiatives in recent

years. Before establishing Idorsia, André served as CFO of Actelion from 2013,

leading the company through its acquisition and playing a crucial role in the

demerger process.

Jean-Paul Clozel, commented:

"André has played a critical role in advancing Idorsia, particularly regarding

our fund-raising and business development activities. He has shown the perfect

qualities of a biotech leader; creativity, solution-oriented, resilient, a team-

player and pragmatic - all qualities that we need to successfully discover and

develop innovative drugs. Having worked with André for more than 10 years, I

have observed that, despite not being a scientist by training, he has a keen

understanding of innovative drug discovery and development. I have absolute

confidence that he is the right person to prepare the company for an exciting

future."

As a result of André becoming CEO, the role of CFO will remain an IEC member and

be taken by Arno Groenewoud, the current Head of Finance and Procurement. In

addition, Julien Gander, Group General Counsel, will become a member of the IEC.

André C. Muller, Chief Financial Officer, commented:

"I am very honored that the Board, its current Chairman, Mathieu Simon, and

Jean-Paul have put this trust in me, particularly following such a long and

successful tenure for Jean-Paul as CEO. I look forward to the challenge of

delivering on the high expectations we have for Idorsia and will work closely

with all colleagues around the globe who never fail to impress with their

commitment and expertise. I welcome Arno and Julien to the executive team.

Having worked closely with both Arno and Julien, I am convinced that their

skills and strategic thinking will be vital as the company moves towards

financial sustainability while managing multiple partnerships."

As of June 13, 2024, the IEC will consist of 5 members: André Muller, CEO;

Martine Clozel, Chief Scientific Officer; Alberto Gimona, Head of Global

Clinical Development; Arno Groenewoud, CFO; and Julien Gander, Group General

Counsel.

At this year's Annual General Meeting, the Board will propose a reduced number

of Board members for the time being. Three of the current Board members - Jörn

Aldag, Felix Ehrat, Peter Kellogg - will not stand for re-election, with only

one new member, Bart Filius, being proposed to the Board. The following Board

members will stand for re-election: Jean-Paul Clozel (proposed Chairman),

Mathieu Simon (Vice-Chairman and Lead Independent Director), Srishti Gupta,

Sophie Kornowski, and Sandy Mahatme.

Mathieu Simon, Chairman of the Board of Idorsia commented:

"This year, the Board has held numerous additional meetings to discuss and

review the various strategic initiatives. I'm very grateful for each member

contributing generously with their expertise and experience. To those not

standing for re-election, I say thank you for serving the company with

professionalism and dedication. Bart's very extensive financing, business

development, and commercial experience in the biotechnology and pharmaceutical

industry would be invaluable to Idorsia. I am completely behind the new

management team, and proposing Jean-Paul to the Chairmanship, and I look forward

to serving as Vice-Chairman and Lead Independent Director with the other members

of the Board focused on guiding Idorsia as we execute our strategy."

Following a competitive selection process, the company considers it appropriate

to invite a fresh perspective by proposing the election of Deloitte AG, Basel as

a new statutory auditor.

Notes to the editor

About Jean-Paul Clozel

Jean-Paul Clozel, 69, is a cardiologist educated in France. He furthered his

training in pharmacology and physiology at the University of Montreal, Canada,

University of California, and San Francisco. After eleven years as a clinician,

he decided to move to applied research and joined the Roche Cardiovascular Drug

Discovery group. During his 12 years at F. Hoffmann-La Roche Ltd, Jean-Paul was

responsible for the selection of the first calcium T-channel blocker and

contributed to several key research programs, such as the selection of the first

orally active renin inhibitor and the characterization of several anti-

thrombotic agents.

During his 25-year-career in cardiovascular research, Jean-Paul has published

widely in peer-reviewed medical and scientific journals. At the same time, his

passion has remained unchanged: being involved as closely as possible in

bringing innovative medicine to "his" patients. He has developed various novel

experimental models allowing for the differentiation of these drugs, work

honored with the 1997 Hoffmann-La Roche Research Prize. In 2007, he was

nominated for a professorship at the Collège de France in Paris, France (Chair

of Technical Innovation).

At the end of 1997, Jean-Paul co-founded Actelion to continue his work in

cardiovascular research and development. In April 2000, he assumed the role of

CEO when Actelion became a publicly traded company and subsequently launched

three blockbuster drugs.

With the acquisition of Actelion by Johnson & Johnson in June 2017, Jean-Paul

co-founded Idorsia, a new biopharmaceutical company that was established by

demerging the drug discovery and early clinical pipeline business from Actelion.

Idorsia is specialized in the discovery and development of small molecules to

provide innovative medicines in areas of unmet patient need.

In the first 7 years of Idorsia's existence, the company launched two innovative

drugs, one for the treatment of insomnia disorder and one for the prevention of

cerebral vasospasm following subarachnoid hemorrhage, with a third medicine on

the verge of being launch for the treatment of uncontrolled blood pressure.

Idorsia continues to perform innovative research across multiple therapeutic

areas to feed its broad and diversified drug development pipeline.

As a result of the establishment of Actelion and Idorsia, several hundred new

jobs have been created in Switzerland as well as in other European countries,

the US and Japan.

About André C. Muller

André C. Muller joined Idorsia at the time of its creation in June 2017 as Chief

Financial Officer from Actelion, where he held the same position since 2013.

Prior to joining Actelion he held various financial positions at Pierre Fabre

SA, an international pharmaceutical and dermo-cosmetic company, serving as CFO

from 2002.

André, a French citizen, has a master's degree in Business Administration from

EMLYON Business School, Lyon, France.

André also serves as a member of the Board of Directors of the listed company

Carmat SA and the unlisted company Chiron Investments AG.

About Bart Filius

Mr. Filius is the former President of Galapagos, a position he held from 2021 to

June 2023. He joined Galapagos in 2014 as Chief Financial Officer and added the

role of Chief Operating Officer in 2017. During his tenure at Galapagos, Bart

managed the substantial growth and financing of the company, including the IPO

on Nasdaq in 2015 and subsequent follow-on financing transactions. He led the

negotiations of the R&D collaboration with Gilead in 2019 and was instrumental

in the build-out of the European commercial organization. Bart is also a member

of the Board and Chairman of the Audit Committee of ProQR Therapeutics since

2019.

Prior to joining Galapagos, Mr. Filius held a variety of executive positions at

Sanofi between 2001 and 2014, including the role of Vice President, Head of

Mergers & Acquisitions, Country manager for The Netherlands and Vice President,

Chief Financial Officer for Europe. Prior to joining Sanofi, Mr. Filius was a

strategy consultant at Arthur D. Little.

Mr. Filius has an MBA degree from INSEAD, France and a bachelor's degree in

business from Nyenrode University, the Netherlands

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 is

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

Andrew C. Weiss

Senior Vice President, Head of Investor Relations & Corporate Communications

Idorsia Pharmaceuticals Ltd, Hegenheimermattweg 91, CH-4123 Allschwil

+41 58 844 10 10

investor.relations@idorsia.com

media.relations@idorsia.com

www.idorsia.com (http://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

terminology such as "estimates", "believes", "expects", "may", "are expected

to", "will", "will continue", "should", "would be", "seeks", "pending" or

"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's

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

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

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

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

performances or achievements that may be expressed or implied by such forward-

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

materialize, or should underlying assumptions prove incorrect, actual results

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

estimated or expected.

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