The European Patent Office (EPO) has granted Addex Therapeutics a broad composition of matter patent (European patent, EP 1 765 795) covering dipraglurant and other mGlu5 negative allosteric modulators (NAM). Dipraglurant is currently in development for the treatment of levodopa-induced dyskinesia in Parkinson's disease patients as well as rare forms of dystonia.
Bharatt Chowrira, CEO at Addex, said, "The granting of this patent continues to broaden the patent estate around our lead programme." Chowrira further added, "Specifically, composition of matter patents have now been granted for dipraglurant in all the major markets - the United States, Europe and Japan. Our intellectual property estate continues to yield key patents protecting novel oral small molecules discovered utilising our industry leading allosteric modulation technology platform. This new patent significantly enhances the value of our dipraglurant franchise and we look forward to advancing dipraglurant into phase II for the treatment of certain rare dystonias in the coming months."
Dipraglurant is an oral, small molecule allosteric modulator that inhibits selectively the metabotropic glutamate receptor 5 (mGlu5), a Class C G-Protein Coupled Receptor (GPCR), with potential to be used in combination with levodopa or dopamine agonists or as a standalone treatment for Parkinson's disease levodopa-induced dyskinesia (PD-LID), motor and non-motor symptoms of Parkinson's disease and other movement disorders.
Data from a recent phase IIa show that dipraglurant met the primary objective of the study by exhibiting a good safety and tolerability profile.
Dipraglurant also demonstrated a statistically significant reduction in LID severity with both 50 and 100 mg doses. Dipraglurant appears to reduce dystonia severity in addition to chorea, the two major LID components. In a double-blind, placebo-controlled study conducted in the US and Europe, the primary objective was to demonstrate safety and tolerability in PD-LID patients. In addition, the trial was designed to evaluate exploratory efficacy as a secondary objective. Efficacy was measured using the modified Abnormal Involuntary Movement Scale (mAIMS), patient diaries documenting "off-time" (impaired voluntary movement), "on-time" (with or without dyskinesia) and sleep. Additional endpoints include the Unified Parkinson's Disease Rating Scale (UPDRS), the Clinician & Patient Global Impression of Change (CGIC & PGIC), and an evaluation of the patients' mood using the Hospital Anxiety & Depression Score.
The trial was supported by a grant from The Michael J Fox Foundation for Parkinson's Research.
There is an increasing body of evidence that mGlu5 inhibition may be a valuable new strategy for treating a number of important diseases and conditions, such as Parkinson's disease, Parkinson's disease levodopa-induced dyskinesia (PD-LID), dystonia, anxiety, depression, pain, tardive dyskinesia, addiction, autism and Fragile X syndrome. With regards to Parkinson's disease, recent clinical and preclinical evidence suggest that mGlu5 inhibition may have an effect on parkinsonian motor symptoms as well as dyskinesia. mGlu5 is found in regions of the brain considered to be key control points in the neuronal movement circuits affected by abnormal signalling by the neurotransmitter glutamate in Parkinson's disease.
Perturbations in glutamate signalling (along with disruptions in dopaminergic signalling) are believed to be an underlying cause of movement disorders like Parkinson's disease and dystonia. As such, inhibiting mGlu5 could act to re-establish normal movement via a non-dopaminergic mechanism. Separately, preclinical findings also suggest that mGlu5 inhibitors may be neuroprotective and may, therefore, hold potential as disease modifying agents that can slow or prevent progression of Parkinson's and other neurological diseases.
Dystonia is a movement disorder that causes the muscles to contract and spasm involuntarily, according to the Dystonia Medical Research Foundation. The involuntary muscle contractions force the body into repetitive and often twisting movements as well as awkward, irregular postures. There are over 20 forms of dystonia, and dozens of diseases and conditions include dystonia as a major symptom. Dystonia may affect a single body area or be generalized throughout multiple muscle groups. Dystonia affects men, women, and children of all ages and backgrounds. Dystonia causes varying degrees of disability and pain, from mild to severe. There is presently no cure, and, although many drugs are utilised to try to treat dystonia, the leading treatment is botulinum toxin injections and many patients are left with inadequate efficacy. Patients also resort to invasive, risky and expensive procedures such as deep brain stimulation to treat dystonia.
Dipraglurant has been shown to effectively reduce dystonia in both a clinical study and preclinical models of Parkinson's disease levodopa-induced dyskinesia (PD-LID). The neurophysiology of different forms of dystonia is thought to be similar and recent preclinical data in dystonia - suggesting that dipraglurant may also work for non-parkinsonian forms of dystonia. Addex plans to initiate phase II pilot studies in certain rare forms of dystonia in the first half of 2013 with the results expected towards the end of 2013.
Addex Therapeutics is a development stage company focused on advancing innovative oral small molecules against rare diseases utilising its pioneering allosteric modulation-based drug discovery platform.