Press Release: Addex's Dipraglurant Restores Synaptic Plasticity in Models of Dystonia

Data published in Neuropharmacology supports therapeutic role of

dipraglurant in this important movement disorder

Geneva, Switzerland, May 17, 2021 -- Addex Therapeutics

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(SIX: ADXN and Nasdaq: ADXN), a clinical-stage pharmaceutical company

pioneering allosteric modulation-based drug discovery and development,

today announced that dipraglurant was able to rescue long-term

impairment of synaptic plasticity in two well validated models of

dystonia. The data were published in the journal, Neuropharmacology

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, under the title "Rescue of striatal long-term depression by chronic

mGlu5 receptor negative allosteric modulation in distinct dystonia

models", by a team led by Antonio Pisani, MD, PhD, from the Department

of Brain and Behavioral Sciences, University of Pavia, and Mondino

Foundation, Pavia, Italy.

"There is an urgent need to identify targets and design effective

therapeutics for dystonia due to the current lack of effective treatment

options. Our studies evaluating the inhibition of mGlu5 receptors with

dipraglurant in two etiologically distinct forms of dystonia models

demonstrate that this target is now validated as a promising approach to

treat dystonia," said Dr Pisani. "In addition, the data suggest there

are common mechanistic bases and signaling pathways impaired in

different forms of dystonia, highlighting the potential of dipraglurant

as a novel therapeutic avenue for the treatment of dystonias. Testing

this hypothesis in the clinic is warranted."

In these studies, the researchers showed that chronic dipraglurant

administration was able to rescue loss of long-term synaptic depression

(LTD), a form of synaptic plasticity, at corticostriatal synapses which

is impaired in both DYT1 mice and GNAL rats, two distinct models of

dystonia.

"The finding that striatal plasticity can be restored by chronic

administration of dipraglurant in multiple rodent models of dystonia is

a very important finding that strengthens the argument that this

approach could be of great utility for normalizing dystonia-related

deficits and further support the rationale for developing dipraglurant

as a treatment for dystonia, including blepharospasm," said Robert

Lütjens, Head of Discovery Biology of Addex. "Dipraglurant is about

to start a pivotal Phase 2b/3 clinical trial for the treatment of

dyskinesia associated with Parkinson's disease and a Phase 2 study in

blepharospasm patients this quarter."

Addex is developing an extended-release formulation of dipraglurant for

the treatment of blepharospasm, a form of dystonia characterized by

involuntary muscle contractions and spasms of the eyelid muscles

resulting in sustained eyelid closure causing substantial visual

disturbance or functional blindness. A placebo-controlled Phase 2

clinical trial of dipraglurant in blepharospasm patients is scheduled to

begin during Q2 2021. Subject to regulatory approval, Addex believes

that dipraglurant may offer an innovative and differentiated treatment

approach for multiple types of dystonia and presents a significant

commercial opportunity.

About Addex Therapeutics:

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Addex Therapeutics is a clinical-stage pharmaceutical company focused on

the development and commercialization of an emerging class of novel

orally available small molecule drugs known as allosteric modulators for

neurological disorders. Allosteric modulators offer several potential

advantages over conventional non-allosteric molecules and may offer an

improved therapeutic approach to conventional "orthosteric" small

molecule or biological drugs. Addex's allosteric modulator drug

discovery platform targets receptors and other proteins that are

recognized as essential for therapeutic intervention. Addex's lead

product candidate, dipraglurant (mGlu5 negative allosteric modulator or

NAM), is poised to start a pivotal registration clinical trial for

Parkinson's disease levodopa induced dyskinesia (PD-LID) in Q2 2021.

Addex is also investigating dipraglurant's therapeutic use in

blepharospasm (a type of dystonia), for which a clinical trial is

expected to be initiated in Q2 2021. Addex's third clinical program,

ADX71149 (mGlu2 positive allosteric modulator or PAM), developed in

collaboration with Janssen Pharmaceuticals, Inc., is scheduled to enter

a phase 2a proof of concept clinical trial for the treatment of epilepsy

in Q2 2021. Addex's GABAB PAM program has been licensed to Indivior PLC,

which is focused on development for the treatment of addiction.

Preclinical programs include GABAB PAM for CMT1A, mGlu7 NAM for PTSD,

mGlu2 NAM for mild neurocognitive disorders, mGlu4 PAM for Parkinson's

disease and mGlu3 PAM for neurodegenerative disorders. Addex shares are

listed on the SIX Swiss Exchange and American Depositary Shares

representing its shares are listed on the NASDAQ Capital Market, and

trade under the ticker symbol "ADXN" on each exchange.

Press Contacts:

Tim Dyer Mike Sinclair James Carbonara

Chief Executive Officer Partner, Halsin Partners Hayden IR

Telephone: +41 22 884 15 +44 (0)20 7318 2955 +1 (646) 755 7412

55 msinclair@halsin.com james@haydenir.com

PR@addextherapeutics.com

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 in respect of the anticipated initiation and progress

of clinical trials and preclinical studies, and its future financing

activities. The words "may," "will," "could," "would," "should," "expect,

" "plan," "anticipate," "intend," "believe," "estimate," "predict,"

"project," "potential," "continue," "target" and similar expressions are

intended to identify forward-looking statements, although not all

forward-looking statements contain these identifying words. Any

forward-looking statements in this press release, are based on

management's current expectations and beliefs and are subject to a

number of risks, uncertainties and important factors that may cause

actual events or results to differ materially from those expressed or

implied by any forward-looking statements contained in this press

release, including, without limitation, uncertainties related to market

conditions. These and other risks and uncertainties are described in the

Company's Annual Report on Form 20-F filed with the SEC on March 11,

2021, as well as market conditions and regulatory review.

Any forward-looking statements contained in this press release represent

Addex Therapeutics' views only as of the date hereof and should not be

relied upon as representing its views as of any subsequent date. Addex

Therapeutics explicitly disclaims any obligation to update any

forward-looking statements, except as required by law.

(END) Dow Jones Newswires

May 17, 2021 01:00 ET (05:00 GMT)