Addex Therapeutics Stumbles on Missed Primary Endpoint in Phase 2 Epilepsy Study

Shares in biopharmaceutical company, Addex Therapeutics (Nasdaq: ADXN), dropped on Monday after the company announced topline data from its Phase 2 study of ADX71149 in the treatment of epilepsy. The company’s share price closed up +1.46% on Tuesday after two choppy trading sessions.

ADX71149, which has been found to be safe and well-tolerated, is being investigated for the treatment of patients with focal onset seizures with suboptimal response to levetiracetam or brivaracetam. Data from 110 evaluable patients showed that the compound did not achieve statistical significance for the primary endpoint of time for patients to reach baseline seizure count when added to standard of care.

Roger Mills, Chief Medical Officer of Addex, commented on the news, saying, “While disappointed that the Phase 2 ADX71149 epilepsy study did not meet the primary endpoint, we are still analyzing the data. We will provide details on data from the full study when this analysis is completed and will work with our partner to determine next steps for the ADX71149 program.”

Glutamate plays a key role in the initiation and spread of seizures. ADX71149 is a selective metabotropic glutamate subtype 2 (mGlu2) receptor positive allosteric modulator (PAM). When activated, the mGlu2 receptor decreases the release of glutamate and consequently, helps to maintain neurotransmitter balance. In the presence of agonist-induced activation, positive allosteric modulation of mGlu2 receptors could result in the normalization of the excessive glutamate release seen during a seizure.

Epilepsy is a challenging unmet medical need, and a significant proportion of the patient population struggling in their day-to-day management of seizures.

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, ADX71149 (mGlu2 positive allosteric modulator or PAM), developed in collaboration with Janssen Pharmaceuticals Inc., has recently completed a Phase 2 clinical study for the treatment of epilepsy. The Company’s second clinical program, dipraglurant (mGlu5 negative allosteric modulator or NAM), is under evaluation for future development in dyskinesia associated with Parkinson’s disease and post-stroke/TBI recovery. Addex partnership with Indivior on GABAB PAM is advancing multiple drug candidates through clinical candidate selection for substance use disorder. Under the agreement with Indivior, Addex is advancing an independent GABAB PAM program for chronic cough through clinical candidate selection. Addex also holds a 20% share in a private company, Neurosterix LLC which is advancing a portfolio of allosteric modulator programs including M4PAM for schizophrenia, mGlu7NAM for stress related disorders and mGlu2NAM for mild neurocognitive 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


Share This Article


About the Author

Addex Therapeutics Stumbles on Missed Primary Endpoint in Phase 2 Epilepsy Study

Catie Corcoran

Biotech Editor