In late 2014, the International Linked Clinical Trials (iLCT) committee prioritised ambroxol for clinical evaluation in Parkinson’s after the preclinical data presented at the LCT meeting suggested that this drug was a promising candidate for drug repurposing. Ambroxol is a commonly used medication in Europe for the treatment for respiratory diseases, it also has anti-inflammatory properties, reducing redness in a sore throat.
In Parkinson’s, there is significant evidence to suggest that unwanted proteins are accumulating in nerve cells, and not being disposed of properly. In particular, researchers have found that ambroxol increases levels of a protein called glucocerebrosidase (GCase) in nerve cells which allows cells to remove waste proteins more effectively. GCase is important in Parkinson’s because some members of the Parkinson’s community have genetic errors in the region of DNA (or gene) that provides the instructions for making GCase. The gene is called GBA, and variations in the GBA gene can increase an individuals risk of developing Parkinson’s.
Between January 2017 and April 2018 a phase 2 clinical trial “Ambroxol in Disease Modification in Parkinson Disease” (AiM-PD study) was conducted by Professor Anthony Schapira, Head of the Department of Clinical Neurosciences, and his research team at University College, London and the Royal Free London Hospital. The results of this clinical study have now been published in JAMA Neurology.
The Study Results
The study involved evaluating the safety and tolerability of ambroxol (1.26g/day) in 17 people with Parkinson’s over 6 months. The investigators also assessed how well the drug was being delivered into the brain and how much it increased GCase activity. They also conducted some basic clinical assessments in the participants to determine disease progression.
The results showed that ambroxol was safe and well tolerated with no reported adverse events during the study. The drug was also found to cross the blood brain barrier and it achieved a good level of penetrance into the brain with a 35% increase overall in GCase protein levels found in participants’ cerebrospinal fluid.
Clinical assessments of the participants suggest that the treatment improved motor features associated with Parkinson’s. There was a 6.8 reduction (indicating improvement) in the clinician-based rating scale* measurement and these effects were seen in those participants with and without GBA mutations. The study was not designed to test disease modification because it was a small cohort safety study without placebo control, therefore the clinical outcomes in this part of the trial should be interpreted with caution. Professor Anthony Schapira said:
The results of the AiM-PD study indicate that ambroxol is safe, well tolerated and able to increase GCase levels in the spinal fluid of people with Parkinson’s. This is an important step to now allow us to find out whether this drug can slow the progress of Parkinson’s. We are grateful to the patients who participated and to Cure Parkinson’s who supported the trial.
The Next Step
The current results are based on a Phase II clinical study. In order for the medical regulators to approve this drug for clinical use in people with Parkinson’s, a programme of research including a double-blinded, placebo-controlled phase 3 clinical trial will be required. This will be a much larger cohort of people over a longer period of time to determine if ambroxol is having a beneficial impact on the participants within the study. The PD Frontline study is aimed at understanding different genotypes of Parkinson’s in order to determine the effects of certain treatments for Parkinson’s which could then become available to the wider Parkinson’s community in the near future.
PD Frontline aims to put people with Parkinson’s at the forefront of research aiming to slow down the progression of the disease. Please take a moment to register and complete this simple survey
Cure Parkinson’s in partnership with Van Andel Institute and the John Black Charitable Foundation, are now actively exploring the next step in the clinical testing of ambroxol.
Dr Simon Stott, Deputy Director of Research at Cure Parkinson’s, commented:
The ambroxol study is important because there are no treatments available for Parkinson’s that slow, stop or reverse Parkinson’s. All of the current medications only deal with the symptoms of the condition – they do nothing to delay the progression of Parkinson’s. This study provides us with the ‘proof of concept’ that we can raise levels of GCase in humans with ambroxol, and that the drug is safe and well tolerated in people with Parkinson’s. If further study shows ambroxol can improve the health and function of cells, it may result in slower disease progression for people with Parkinson’s.
*the Movement Disorders Society Unified Parkinson’s Disease Rating Scale Part III
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