Addex Initiates Pivotal Phase 2b/3 Study for Dyskinesia Associated with Parkinson’s

 Addex Therapeutics Ltd (SIX: ADXN, Nasdaq: ADXN), a clinical-stage pharmaceutical company pioneering allosteric modulation-based drug discovery and development, announced today that screening of patients has started for its pivotal Phase 2b/3 study with dipraglurant for dyskinesia associated with Parkinson’s disease (PD-LID). Dyskinesia is believed to be caused by increased glutamatergic neurotransmission. Dipraglurant selectively targets the metabotropic glutamate receptor subtype 5, or mGlu5 to downregulate this neurotransmission through allosteric modulation.

The registration program comprises two placebo-controlled studies. The first, Study 301, is a double-blind, placebo-controlled, parallel group design Phase 2b/3 pivotal clinical trial of dipraglurant (100 mg tid) in 140 PD-LID patients at approximately 50 sites in the U.S. The primary endpoint will evaluate efficacy in reducing PD-LID symptoms as measured by the Unified Dyskinesia Rating Scale, or UDysRS at week 12 compared to baseline. Secondary endpoints include Clinician's Global Impression of Severity (CGI-S) and standardized patient diary based assessments of "On" time without troublesome dyskinesia and "Off" time.

“The start of this pivotal study with dipraglurant is a significant milestone in Addex’s history and we are looking forward to evaluating this novel therapeutic in patients that urgently need more treatment options,” said Tim Dyer, Chief Executive Officer of Addex. “This is the second clinical study initiated this year following the recent start of a Phase 2 study in epilepsy with ADX71149 by our strategic partner, Janssen Pharmaceuticals. We also expect to start an exploratory Phase 2 study with dipraglurant in blepharospasm patients in the coming months.”

In a Phase 2a study dipraglurant met its primary endpoint by being generally well tolerated and showing no clinically significant safety issues. In addition, at Day 1 and Day 14, dipraglurant showed statistically significant effects on PD-LID clinical symptoms, as measured using the modified abnormal involuntary movement scale, or mAIMs. However, statistical significance was not achieved at Day 28 due in part to an increasing placebo response. The registrational 301 study has an improved design incorporating multiple methods for mitigating placebo response.

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