Stockholm, Sweden

Calliditas Announces Agreement to Acquire Controlling Interest

adds late-stage orphan pipeline asset and platform in inflammation and fibrosis. Calliditas to acquire 62.7% of Genkyotex

for 20.3M in cash at 2.80 per share in an off-market transaction. Following the closing of the control transaction

a mandatory simplified cash tender offer on the same terms for the remaining outstanding shares would be launched. Total consideration

for 100% of Genkyotex would amount to ~ 32M, not including milestones of up to 55M payable upon regulatory approvals

Calliditas Therapeutics AB (publ) ("Calliditas"

or the Company) (Nasdaq OMX - CALTX; NASDAQ - CALT) announced today that the Company has reached an agreement to acquire

a controlling interest in Genkyotex SA ("Genkyotex") (Euronext Paris & Brussels: FR0013399474 - GKTX),

a leader in NOX inhibition therapies.

Genkyotex's lead clinical candidate,

setanaxib (GKT831), is in development for Primary Biliary Cholangitis (PBC), a chronic orphan liver disease resulting from progressive

destruction of the bile ducts in the liver. In a Phase 2 clinical trial, setanaxib demonstrated evidence of anti-fibrotic activity

combined with a favorable tolerability profile, as well as a statistically significant impact on fatigue. In April 2020, Genkyotex

completed an End of Phase 2 meeting with the US Food and Drug Administration (FDA) and in June 2020 obtained scientific advice

from the European Medicine Agency's (EMA) Scientific Advice Working Party (SAWP) that provide a path forward for the late

stage development and potential registration of setanaxib in PBC.

"We believe this transaction represents

an exciting expansion of our pipeline in orphan diseases related to inflammation and fibrosis", says Calliditas' CEO

Ren e Aguiar-Lucander. "We believe Genkyotex's novel NOX inhibition technology may have broad clinical utility

not just in PBC, but as a platform therapy with the potential to target other fibrotic indications, including Primary Sclerosing

Cholangitis (PSC), selected kidney diseases and Idiopathic Pulmonary Fibrosis (IPF), in which an investigator led Phase 2 trial

is expected to start recruitment later this year."

"We look forward to leveraging our

strong late stage clinical team, CMC and regulatory expertise as well as our learnings from our Phase 3 Nefecon program to navigate

and execute an efficient path forward for setanaxib. We continue to deliver on our strategy focusing on adding late stage assets

with an orphan focus and encouraging data in patients to build a company focused on delivering solution for patients with diseases

with high unmet needs", Ms. Aguiar-Lucander concludes.

Calliditas has agreed to acquire through

an off-market block trade 7,236,515 ordinary shares of Genkyotex representing 62.7% of the share capital and voting rights of

Genkyotex1 from Genkyotex's largest shareholders and management team (the "Block Sellers")2

for a total consideration of 20.3M payable in cash at closing ( 2.80 per ordinary share) representing a 25% premium

over Genkyotex's volume weighted average price (VWAP) over the preceding month immediately prior to this announcement and

non- transferable contingent rights to receive additional cash payments on confirmation of regulatory approvals or marketing authorizations

of setanaxib, as described below. The off-market block trade is expected to close in early October 2020 and remains subject

to customary conditions precedent, including the clearance from the French Minister of Economy and Finance regarding foreign investments

into France. Calliditas will finance the block trade from its cash reserves.

Based on the total number of issued shares and voting rights of Genkyotex on the date of this press release (11,548,562)

The Block Sellers are Andera Partners (25,3%), Eclosion 2 (12,1%), Vesalius Biocapital (9,4%), Neomed Inovation (8,1%),

N5 Investments (0,6%), Wellington Partners (4,2%), Elias Papatheodorou (1,3%), Philippe Wiesel (1%) and Alexandre Grassin (0,6%).

Calliditas is seeking to acquire all outstanding

Genkyotex shares and, as soon as reasonably practicable after and subject to completion of the off-market block trade, in compliance

with French and Belgian securities law, Calliditas will file with the French Financial Market Authority (Autorit des

March s Financiers - the "AMF") a mandatory simplified cash tender offer for the remaining Genkyotex

shares on the same terms as the block trade, 2.80 per share in cash and non-transferable contingent rights as further described

below. The tender offer will be followed by a squeeze-out of the non-tendered shares under the same terms (including the contingent

rights) if the legal requirements are met. Total acquisition cost would in such case amount to approximately 32.3M with total

contingent rights amounting to a maximum of 55M, subject to future regulatory approvals of setanaxib.

The Block Sellers and the Genkyotex shareholders

who tender their shares in the centralized tender offer will be eligible to the following additional cash payments (expressed in

relation to 100% of the Genkyotex shares on a fully diluted basis) on confirmation of regulatory approvals or marketing authorizations

of setanaxib no later than within ten years of the closing of the tender offer:

Bryan Garnier & Co acted as financial

advisor to Calliditas in this transaction. Latham & Watkins LLP and Vinge acted as legal advisers to Calliditas.

further information, please contact:

Ren e Aguiar-Lucander, CEO, Calliditas

Tel.: +46 722 52 10 06, email: renee.lucander@calliditas.com

Mikael Widell, Investor Relations,

Tel.: +46 703 11 99 60, email: mikael.widell@calliditas.com

The information in the press release

is information that Calliditas is obliged to make public pursuant to the EU Market Abuse Regulation. The information was sent for

publication, through the agency of the contact persons set out above, on August 13, 2020 at 07:00 a.m. CET.

This press release does not constitute

an offer to purchase, or a solicitation of an offer to sell, any securities of Genkyotex. The documentation relating to the tender

offer which, if filed, will state the terms and conditions of the tender offer, will be submitted to the review of the AMF. Investors

and shareholders are strongly advised to read the documentation relating to the tender offer when it becomes available, if the

offer is filed, as well as any amendments and supplements to those documents as they will contain important information about Calliditas,

Genkyotex and the proposed transaction.

The transaction is notably subject to

the obtaining of required regulatory authorizations and other customary conditions. The tender offer would only be filed with the

AMF after such conditions have been fulfilled and the off-market block trade has been closed.

This press release must not be published,

broadcast or distributed, directly or indirectly, in any country in which the distribution of this information is subject to legal

restrictions. The tender offer will not be open to the public in jurisdictions in which its launch is subject to legal restrictions.

The publication, broadcasting or distribution of this press release in certain countries may be subject to legal or regulatory

restrictions. Therefore, persons located in countries where this press release is published, broadcasted or distributed must inform

themselves about and comply with such restrictions. Calliditas disclaims any responsibility for any violation of such restrictions.

Calliditas Therapeutics is a specialty

pharmaceutical company based in Stockholm, Sweden focused on identifying, developing and commercializing novel treatments in orphan

indications, with an initial focus on renal and hepatic diseases with significant unmet medical needs. Calliditas' lead product

candidate, Nefecon, is a proprietary, novel oral formulation of budesonide, an established, highly potent local immunosuppressant,

for the treatment of the autoimmune renal disease IgA nephropathy, or IgAN, for which there is a high unmet medical need and there

are no approved treatments. Calliditas is running a global Phase 3 study within IgAN and, if approved, aims to commercialize Nefecon

in the United States. Calliditas is listed on Nasdaq Stockholm (ticker: CALTX) and the Nasdaq Global Select Market (ticker: CALT).

Visit www.calliditas.com for further information.

Genkyotex is the leading biopharmaceutical

company in NOX therapies, listed on the Euronext Paris and Euronext Brussels markets. Its unique platform enables the identification

of orally available small-molecules which selectively inhibit specific NOX enzymes that amplify multiple disease processes such

as fibrosis, inflammation, pain processing, cancer development, and neurodegeneration. Genkyotex is developing a pipeline of first-in-class

product candidates targeting one or multiple NOX enzymes. The lead product candidate, setanaxib (GKT831), a NOX1 and NOX4 inhibitor

has shown evidence of anti-fibrotic activity in a Phase II clinical trial in primary biliary cholangitis (PBC, a fibrotic orphan

disease). Based on its positive Phase II results, a phase 3 trial with setanaxib in PBC is being planned. Setanaxib is also being

evaluated in an investigator-initiated Phase II clinical trial in Type 1 Diabetes and Kidney Disease (DKD). A grant from the United

States National Institutes of Health (NIH) of $8.9 million was awarded to Professor Victor Thannickal at the University of Alabama

at Birmingham (UAB) to fund a multi-year research program evaluating the role of NOX enzymes in idiopathic pulmonary fibrosis (IPF),

a chronic lung disease that results in fibrosis of the lungs. The core component of this program is a Phase 2 trial with setanaxib

in patients with IPF scheduled to recruit patients in the course of 2020. This product candidate may also be active in other fibrotic

Forward-Looking Statements

This press release contains forward-looking

statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation,

statements regarding Calliditas' strategy, business plans and focus. The words "may," "will," "could,"