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 robust anti-tussive activity of its novel gamma-aminobutyric acid sub-type B receptor (GABAB) positive allosteric modulator (PAM) in multiple preclinical models of chronic cough compared to reference drugs.

Some of these preclinical data with Addex GABAB PAM drug candidate will be presented on June 7, 2025 at the 10^th American Cough Conference, in Dulles, Virginia by Dr Mikhail Kalinichev, Head of Translational Science at Addex.

In models of chronic cough, the GABAB PAM drug candidate significantly reduced citric acid-induced cough frequency, increased cough latency and showed no signs of tolerance after sub-chronic treatment. In the same model, the antitussive efficacy of the Addex GABAB PAM drug candidate appears to be superior to that observed with nalbuphine, baclofen, codeine or a P2X3 inhibitor. In addition, the tolerability of the GABAB PAM candidate demonstrated better tolerability and a wider therapeutic margin than that observed with nalbuphine, baclofen, or codeine, while being similar to that of a P2X3 inhibitor, based on the compound’s activity on respiratory rate.

“The preclinical data obtained to date demonstrate the huge therapeutic potential of our highly selective GABAB PAM. Following in vivo proof of concept seen in a range of cough models, we are now ready to advance this candidate molecule into IND enabling studies,” said Dr Kalinichev. “Chronic cough continues to be difficult to treat, and several different approaches being evaluated in clinical trials. Based on the data we have collected to date, we believe our GABAB PAM candidate has the potential to be an effective, once-daily treatment for patients with refractory chronic cough and other conditions.”

“This data with our novel, once daily, orally available GABAB PAM drug candidate clearly demonstrates the potential of our allosteric modulator approach to deliver a better effect than baclofen for this clinically validated drug target,” said Tim Dyer, CEO of Addex. “Congratulations to the team and we look forward to advancing this candidate rapidly through IND enabling studies and into the clinic so we can hopefully provide better treatment options for patients.”