Preclinical cough data for Addex (NASDAQ: ADXN) GABAB PAM program

Rhea-AI Filing Summary

Addex Therapeutics filed a Form 6-K to furnish a press release highlighting new preclinical results for its GABAB positive allosteric modulator (PAM) candidate in an idiopathic pulmonary fibrosis (IPF)-related chronic cough model. In bleomycin-exposed animals, once-daily dosing produced robust and sustained reductions in cough frequency and longer cough latency, along with improved lung pathology measures such as lower Ashcroft scores and less affected lung tissue. The compound showed a favorable safety profile with stable respiratory rate and body temperature and was well tolerated, supporting its potential for chronic use in chronic cough. The company also reiterates broader work on allosteric modulators in neurological and related disorders.

Key Terms

GABAB positive allosteric modulator, bleomycin (BLM)-induced idiopathic pulmonary fibrosis (IPF), Ashcroft scores, allosteric site, +2 more

6 terms

GABAB positive allosteric modulator medical

"encouraging preclinical data demonstrating antitussive activity of its GABAB positive allosteric modulator (PAM) candidate"

bleomycin (BLM)-induced idiopathic pulmonary fibrosis (IPF) medical

"in a bleomycin (BLM)-induced idiopathic pulmonary fibrosis (IPF) exacerbated chronic cough model"

Ashcroft scores medical

"Improved lung pathology outcomes, including lower Ashcroft scores and reduced percentage of affected lung tissue"

allosteric site medical

"Targeting an allosteric site of the receptor encompasses many advantages, including higher selectivity"

non-human primates medical

"including non-human primates announced last week, robust antitussive efficacy of the compound"

Non-human primates are members of the primate family other than people — such as monkeys and apes — that are used in biomedical research because their biology is closer to humans than rodents. For investors, results from studies in these animals can strongly influence a drug or vaccine’s safety profile, development timeline, regulatory chances and costs, acting like a high-fidelity dress rehearsal before human clinical trials.

mGlu5 negative allosteric modulator medical

"dipraglurant (mGlu5 negative allosteric modulator or NAM), is under evaluation for future development"

Form 6-K: How Foreign Companies Report to the SEC →

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

Form 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a-16 OR 15d-16 UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of April 2026

Commission File Number: 001-39179

Addex Therapeutics Ltd
(Translation of registrant's name into English)

Chemin des Mines 9,
CH-1202 Geneva,
Switzerland
(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.
Form 20-F [ X ]      Form 40-F [   ]

On April 29, 2026, the Registrant issued a press release, a copy of which is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

(c) Exhibit 99.1. Press release dated April 29, 2026

INCORPORATION BY REFERENCE

Exhibit 99.1  to this Report on Form 6-K shall be deemed to be incorporated by reference into the registration statement on Form F-3 (Registration No. 333-291644) of Addex Therapeutics Ltd and the registration statement on Form S-8 (Registration No. 333-255124 and No. 333-272515) of Addex Therapeutics Ltd (including any prospectuses forming a part of such registration statements) and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished.

RISK FACTORS

Our business faces significant risks. You should carefully consider all of the information set forth in this Report on Form 6-K and in our other filings with the United States Securities and Exchange Commission, or the SEC, including the risk factors related to our business set forth in our Annual Report on Form 20-F for the year ended December 31, 2024 filed with the Securities and Exchange Commission on May 15, 2025. Our business, financial condition, results of operations and growth prospects could be materially adversely affected by any of these risks. This report also contains forward-looking statements that involve risks and uncertainties. Our results could materially differ from those anticipated in these forward-looking statements, as a result of certain factors including the risks described in our Annual Report and our other SEC filings.

 

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

		Addex Therapeutics Ltd
		(Registrant)
Date: April 29, 2026		/s/ Tim Dyer
		Tim Dyer
		Chief Executive Officer

EXHIBIT INDEX

Exhibit Number		Description
99.1		Press release dated April 29, 2026

EXHIBIT 99.1

Addex GABAB PAM Candidate Demonstrates Solid Anti-Tussive Activity in Bleomycin IPF-Related Chronic Cough Model

Ad Hoc Announcement Pursuant to Art. 53 LR

Geneva, Switzerland, April 29, 2026 - Addex Therapeutics (SIX: ADXN and Nasdaq: ADXN), a clinical-stage biopharmaceutical company focused on developing a portfolio of novel small molecule allosteric modulators for neurological disorders, announced today encouraging preclinical data demonstrating antitussive activity of its GABAB positive allosteric modulator (PAM) candidate in a bleomycin (BLM)-induced idiopathic pulmonary fibrosis (IPF) exacerbated chronic cough model.

“Chronic cough remains a significant unmet medical need, particularly in patients suffering from idiopathic pulmonary fibrosis (IPF), where persistent coughing substantially impacts quality of life and worsens disease burden,” said Tim Dyer, CEO of Addex. “In studies to date, including non-human primates announced last week, robust antitussive efficacy of the compound is combined with a stable respiratory and systemic safety profile, further supporting the therapeutic promise of our GABAB PAM as a novel and well-tolerated approach for chronic cough management.”

In studies evaluating chronic once-daily (QD) administration of a lead GABAB PAM candidate in BLM-exposed animals, robust and sustained antitussive efficacy was observed, with significant reductions in cough frequency and increased cough latency over the treatment period. Improved lung pathology outcomes, including lower Ashcroft scores and reduced percentage of affected lung tissue suggesting an impact on fibrosis, were demonstrated compared to untreated BLM-exposed animals at both Day 7 and Day 28. The safety profile remained favorable, with no meaningful changes in respiratory rate, or body temperature. The compound was well tolerated throughout the study, supporting its potential for chronic administration.

About GABAB activation and chronic cough
The main inhibitory neurotransmitter GABA activates ionotropic (GABAA) and metabotropic (GABAB) types of receptors. GABAB receptors are widely expressed throughout the central and peripheral cough neural circuit as well as in the lungs and airways. Activating GABAB receptors to treat chronic cough has been clinically validated with baclofen, a selective GABAB agonist, that binds the receptor within the GABA binding, orthosteric site. Baclofen is used off-label to treat chronic cough patients, but its wider use is limited due to serious side effects including sedation, short half-life and gradual loss of efficacy during chronic treatment. Targeting an allosteric site of the receptor encompasses many advantages, including higher selectivity, better tolerability and lack of tolerance compared to an orthosteric compound.

About Addex Therapeutics

Addex Therapeutics is a clinical-stage biopharmaceutical company focused on developing a portfolio of novel small molecule allosteric modulators for neurological disorders. Addex’s lead drug candidate, dipraglurant (mGlu5 negative allosteric modulator or NAM), is under evaluation for future development in brain injury recovery, including post-stroke and traumatic brain injury recovery. Addex’s partner, Indivior, has selected a GABAB PAM drug candidate for development in substance use disorders and has successfully completed IND enabling studies. Addex is advancing an independent GABAB PAM program for chronic cough. Addex holds a 20% equity interest in a private spin out company, Neurosterix LLC, which is advancing a portfolio of allosteric modulator programs, including M4 PAM for schizophrenia, psychosis and mood-related disorders and mGlu7 NAM for mood disorders. In addition, Addex has invested in Stalicla, a private Swiss company pioneering a precision medicine approach for neurodevelopmental and neuropsychiatric 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. For more information, visit www.addextherapeutics.com

Contacts:

Tim Dyer
Chief Executive Officer
Telephone: +41 22 884 15 55
PR@addextherapeutics.com Mike Sinclair
Partner, Halsin Partners
+44 (0)7968 022075
msinclair@halsin.com

Addex 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 statements about the intended use of proceeds of the offering. 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 greater detail in the section entitled “Risk Factors” in Addex Therapeutics’ Annual Report on Form 20-F, prospectus and other filings that Addex Therapeutics may make with the SEC in the future. 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.

FAQ

What did Addex Therapeutics (ADXN) report in this Form 6-K?

Addex reported preclinical data showing its GABAB PAM candidate reduced cough and improved lung pathology in an IPF-related chronic cough animal model. The compound also showed a favorable safety profile, supporting its potential for chronic cough treatment development.

How did Addex’s GABAB PAM perform in the IPF-related chronic cough model?

The GABAB PAM showed robust, sustained antitussive efficacy with significant reductions in cough frequency and increased cough latency during once-daily dosing. It also improved lung pathology markers, including lower Ashcroft scores and reduced affected lung tissue in bleomycin-exposed animals.

What safety profile was observed for Addex’s GABAB PAM candidate?

In the preclinical studies, the compound showed a favorable safety profile, with no meaningful changes in respiratory rate or body temperature. It was well tolerated throughout the study period, supporting its potential suitability for chronic administration in future development.

Why is GABAB activation relevant for treating chronic cough, according to Addex?

GABAB receptors are widely expressed in the central and peripheral cough neural circuits, lungs and airways. Activating these receptors has been clinically validated with baclofen for chronic cough, suggesting GABAB modulation is a promising mechanism for controlling persistent coughing symptoms.

How does a GABAB positive allosteric modulator differ from baclofen for chronic cough?

Baclofen is a GABAB agonist binding the orthosteric GABA site and is used off-label but limited by sedation, short half-life and tolerance. A positive allosteric modulator targets an allosteric site, which may offer higher selectivity, better tolerability and reduced tolerance development.

What other programs is Addex Therapeutics (ADXN) advancing?

Addex is developing dipraglurant, an mGlu5 negative allosteric modulator, for brain injury recovery. It also has partnered and spin-out programs in GABAB PAMs for substance use disorders, M4 PAM and mGlu7 NAM for psychiatric indications, and investments in precision medicine company Stalicla.

Filing Exhibits & Attachments

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Press Releases

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