More research needed to investigate iron in Parkinson’s

The study was investigating the potential of a drug called deferiprone on delaying the progression of Parkinson’s. Deferiprone is an iron chelator, which means it removes extra iron from areas of the body that have too much, and moves it to areas that need more. 

The clinical trial (FAIRPARK-II) involved 372 people newly diagnosed with Parkinson’s from 23 centres across Europe. They had not previously received any medication for their Parkinson’s. Over 9 months, participants either received deferiprone or a dummy drug (placebo) twice a day. 

Why is iron important? 

Iron has a few different roles in the brain. It supports the development of neurons and kick-starts the production of dopamine, a brain chemical which is lost in Parkinson’s. 

However, previous studies have suggested that too much iron in the brain can cause damage, resulting in the loss of dopamine producing cells. And high levels of iron have been seen in the brains of people with Parkinson’s.

This clinical trial set out to see if deferiprone could remove excess iron from the brains of people newly diagnosed with Parkinson’s, and in turn improve symptoms by reducing damage and increasing dopamine. 

Smaller Phase 2 studies that have previously taken place slowed progression of Parkinson’s symptoms in participants who were receiving deferiprone and a dopamine replacement therapy. 

What are the results? 

Participants who received the placebo had their Parkinson’s symptoms worsen a little over the 9 months of the study. 

Unexpectedly, in those who received deferiprone, their Parkinson’s symptoms worsened slightly more than those who received the placebo. 

Following the trial, all participants were given dopamine replacement treatments and both groups are benefiting equally from the treatment. 

Read the full results in the New England Journal of Medicine.

Why could this have happened?

The results from this trial could be affected by the fact the participants were newly diagnosed and not taking dopamine replacement therapy before or during the trial. 

When you have Parkinson’s, dopamine producing cells are lost, which means the remaining cells must work harder to produce enough dopamine. To do this, they need iron. Taking it away might actually result in less dopamine being available in the brain. 

Previous trials looking at deferiprone have included participants who were already receiving medication for their Parkinson’s, which help boost the levels of dopamine without the need for iron. This could explain why the deferiprone had a more beneficial effect in previous trials, as it removed the excess iron which was damaging the cells without impacting dopamine production.

However in this study, participants were not receiving any other treatment to help increase the amount of dopamine. By removing the iron, this might actually have made symptoms worse.

What’s next? 

The researchers suspect that studying the effects of the drug over a longer time period in people with Parkinson’s also receiving dopamine replacement therapy might show that it can have some benefit.

Naveena Kapur, Research Communications Manager at Parkinson’s UK, said: 

"These results were not as expected, which is always disappointing, but the study leaves a few questions unanswered.

"It will be interesting to follow the next steps of the research which will investigate whether dopamine replacement therapy in combination with deferiprone would give better results. It’s clear that further research is also necessary to understand at what time during a person’s Parkinson’s progression might be best for deferiprone treatment."