Addex Provides Update on ADX71149 Phase 2 Epilepsy Study

Ad Hoc Announcement Pursuant to Art. 53 LR

Geneva, Switzerland, April 29, 2024 - Addex Therapeutics (SIX and Nasdaq: ADXN), a clinical-stage biopharmaceutical company focused on developing a portfolio of novel small molecule allosteric modulators for neurological disorders, today announced top-line data from a Phase 2 epilepsy study evaluating adjunctive ADX71149 (JNJ-40411813) administration in patients with focal onset seizures with suboptimal response to levetiracetam or brivaracetam. The Phase 2 study did not achieve statistical significance for the primary endpoint of time for patients to reach baseline seizure count when ADX71149 was added to standard of care.

“While disappointed that the Phase 2 ADX71149 epilepsy study did not meet the primary endpoint, we are still analyzing the data,” said Roger Mills, Chief Medical Officer of Addex. “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.”

The data were reported from a total of 110 evaluable patients, who each received either 50 mg or 100 mg of ADX71149 twice daily (100 mg or 200mg twice daily, respectively, for patients receiving CYP3A4 inducing anti-seizure medication) in addition to their standard dose of levetiracetam or brivaracetam and up to three other anti-seizure drugs. Adjunctive administration of ADX71149 was safe and well tolerated.

“While this is disappointing news for us and our partner, Janssen, we remain focused on advancing the rest of our portfolio of allosteric modulator programs towards clinical studies,” said Tim Dyer, CEO of Addex. “In particular, we are making great progress in our GABAB PAM collaboration with Indivior, which is on track to select drug candidates for IND enabling studies in June this year for substance use disorder and chronic cough programs.”

About the Study:
ADX71149 is a selective metabotropic glutamate subtype 2 (mGlu2) receptor positive allosteric modulator (PAM). The multi-center Phase 2 study was designed to assess the efficacy, safety, tolerability, and pharmacokinetics of adjunctive ADX71149 administration in patients with focal onset seizures with suboptimal response to levetiracetam or brivaracetam. The primary objective of the study was to evaluate the efficacy of ADX71149 in combination with levetiracetam or brivaracetam using a time to baseline seizure count endpoint. Part 1 of the study evaluated the acute efficacy of ADX71149 over 4 weeks. Patients who did not reach their monthly baseline seizure count in Part 1 continued double-blind treatment during Part 2 until they reached their monthly baseline seizure count or 8 weeks, deemed the maintenance efficacy phase. More information on the study can be found with Clinicaltrials.gov identifier NCT04836559.