What’s in the pipeline for Parkinson’s?
In the past 20 years, phenomenal progress has been made in unravelling the complex chain of events that leads to the damage and loss of dopamine producing brain cells in Parkinson’s. But how are these discoveries being turned into new treatments?
Understanding how our brain cells work normally and what changes happen
in Parkinson’s provides huge opportunities for developing new treatments. Although our understanding is not yet complete, scientists have found some game-changing pieces of the puzzle, including changes in key genes and the fundamental processes that cause the condition.
Now, thanks to this progress, new treatments are being created and tested that have the potential to slow, stop or even reverse Parkinson’s.
In this article, we take you through the different phases of clinical trials that treatments have to go through before they can be approved, and introduce you to some of the promising therapies that are coming through the pipeline.
New treatments are given to a small number of people to test for safety, side effects and to find the best dose. These studies involve a small group of participants who may be healthy volunteers or people with the condition.
Phase 1 studies can give us some clues about whether the treatment may be effective. But because they involve a very small number of people and don’t include a comparison group, any positive effects need to be taken with a large pinch of salt.
What’s in phase 1 for Parkinson’s?
Vaccines for Parkinson’s could work by prompting the body to recognise the alpha-synuclein protein as a foreign invader, triggering the immune system to clear some of the protein. Two different vaccines are currently being tested in early stage trials — one developed by US company Prothena, and the other by Austrian company Affiris.
Cell transplantation allows cells, like those lost in Parkinson’s, to be replaced. TRANSEURO is a European trial testing the safety and effectiveness of transplanting foetal cells to repair the brain. If successful, it could provide a blueprint for emerging stem cell therapies. The trial, which involves participants across several countries including the UK, is well underway and should finish in 2019.
Gene therapy works by using genes as a treatment. A trial of a gene therapy called VY-AADC01, which aims to help current Parkinson’s drugs work better, is currently underway in 10 people with advanced symptoms in the US. The company released promising interim results in 2016 and is already planning the next stage of studies.
Mindfulness therapy is a psychological therapy that may reduce stress and anxiety. A small pilot study is now underway in the UK to find out whether mindfulness is helpful for people with Parkinson’s and if it can be successfully delivered via a video call over the internet.
Treatments are tested in a larger group who have the condition to see whether they have a beneficial effect.
Most phase 2 studies will include a comparison group who receive a placebo (or dummy treatment). This means the researchers can see whether people who receive the treatment do better than those who just think they receive the treatment (the placebo effect).
This is a major test of any new treatment’s credentials. If a treatment shows effectiveness in phase 2 it’s very promising, but it still needs to pass the final hurdle of phase 3 trials.
What’s in phase 2 for Parkinson’s?
Exenatide, a drug that is currently used to treat type 2 diabetes, has shown potential for slowing the course of Parkinson’s in the lab. Following promising results in 2013, a phase 2 trial was completed in 2017 and now the research team at UCL are developing plans for further studies of exenatide involving more participants. You can read about the latest trial results here.
Simvastatin is a treatment usually used to lower cholesterol. Previous studies have suggested that people who take statins are at reduced risk of Parkinson’s. A phase 2 trial in 198 people in the early-stages of the condition is now underway in the UK to see if simvastatin can slow the development of the condition. It is due to complete in 2019.
Deferiprone is an iron-chelating drug that is taken by people with rare blood disorders. A phase 1 trial showed potential for reducing iron levels in the brains of people with Parkinson’s. A phase 2 trial involving 140 participants is taking place in Canada, France and the UK, with recruitment expected to start in 2017.
GDNF is a special protein naturally produced inside the brain that supports the survival of many types of brain cell, including those lost in Parkinson’s. A phase 2 trial is now complete and results are expected soon.
This anti-cancer drug hit the headlines in 2016 when results from a phase 1 trial in the US suggested improvements in twelve people with advanced stage Parkinson’s. A phase 2 trial has recently begun in the US.
In this final stage of clinical trials, treatments are tested to prove they are safe and effective in a large number of people over a more extended period of time.
Phase 3 clinical trials often take place across many countries (or even continents!), involve hundreds of participants and may run for several years. This is important for making sure that the treatment is safe and effective in the long-term.
What’s in phase 3 for Parkinson’s?
Apomorphine is already used by many people with Parkinson’s to help control symptoms, especially in the later stages of the condition. The drug is taken by injection or pump. Phase 3 trials are now underway in the US and UK to test a new way of delivering apomorphine that involves placing a special strip under the tongue. These studies are due to finish in 2018.
Isradipine is used to treat high blood pressure and has shown promise for Parkinson’s. A large phase 3 trial is now being planned to assess whether isradipine can slow the progression of the condition. The trial will take place over three years in the US and Canada.
Inosine may have anti-oxidant and anti-inflammatory effects in the brain. Phase 2 trials showed that the drug has a good safety profile and had potential for slowing the development of Parkinson’s. A large phase 3 trial began in the US in 2016 and is scheduled to end in 2020.
Rivastigmine is a drug that is currently used to improve thinking and memory in people with dementia. In 2016, a phase 2 clinical trial of rivastigmine in people with Parkinson’s showed that this drug may also have the potential to improve balance and prevent falls. A phase 3 trial is now being planned.
This is by no means an exhaustive list of all the studies underway globally testing new treatments for Parkinson’s, just a selection of some of the most interesting.
It’s impossible to predict which of these potential therapies will work and which will not. At each step along the journey, research becomes more expensive. And for every potential therapy that enters the process, perhaps one in a thousand will end up being approved for use. While we can’t know exactly what’s next, we can be optimistic about the level and type of ongoing research into Parkinson’s — all of which aims to improve, and perhaps more importantly reverse, the course of Parkinson’s for all of those living with the condition.