Parkinson’s UK
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Update from the clinical trial of prasinezumab — a vaccine for Parkinson’s

Initial data from the latest phase 2 study of prasinezumab in 316 people with Parkinson’s gives an insight into the trial.

Photo by Abby Anaday on Unsplash

An update from the PASADENA clinical trial — a phase 2 trial of an anti-alpha synuclein treatment that is due to finish in February 2021 — has been presented by Roche. The study aims to assess whether one year of therapy can reduce both motor and non-motor symptoms more than a placebo.

The data highlights that those taking part in the trial are representative of a wider Parkinson’s population and, as such, are suitable for testing the potential beneficial effects of prasinezumab. You can read more about the study participants in this news piece from Parkinson’s News Today.

While it is too early to know if prasinezumab will slow the progression of Parkinson’s, this blog shares more about this therapy works and the aims of the trial.

How do vaccines for Parkinson’s work?

A vaccine therapy for Parkinson’s would aim to use the body’s own immune response to protect precious brain cells.

Research has shown that in the brain cells that are lost in Parkinson’s there is a build-up of a sticky protein called alpha-synuclein. These sticky proteins form toxic clumps, called Lewy bodies, that are believed to play a crucial role in the death of these cells.

You can read more about the alpha-synuclein protein in this previous blog post.

There are multiple vaccines that have been developed targeting alpha-synuclein at various stages of clinical trials. Prasinezumab, developed by Prothena in collaboration with Roche, is an antibody designed to selectively stick to clumps of alpha-synuclein protein, in turn switching on the immune system’s ability to see and target them for destruction.

By clearing alpha-synuclein clumps, prasinezumab has been designed with the intention to slow down Parkinson’s — something no current treatment is able to do.

Research into prasinezumab to date

In animal models of Parkinson’s, prasinezumab has been shown to reduce the accumulation of the toxic clumps, protecting brain cells and slowing the progression of symptoms.

A phase 1b study in 80 people with Parkinson’s was then carried out to investigate if the treatment was safe. The results, published in June 2018, showed that the therapy was safe and well-tolerated and that levels of alpha-synuclein in the blood were reduced by up to 97% after a single injection.

And so the current Roche-sponsored, two-part phase 2 study, called PASADENA began to further test the safety of prasinezumab and start to investigate if it could slow the progression of the condition.

The PASADENA clinical trial

The ongoing phase 2 study is a double-blind, placebo-controlled trial that is being carried out in 2 parts.

Part 1:

Once every 4 weeks for a year, 316 participants with early-stage Parkinson’s were randomly assigned to receive either:

  • the active treatment (a low dose or 1500 mg, or a high dose of 4500/3500 mg, depending on body weight), or
  • a placebo.

All those finishing this first part of the trial could then decide whether to take part 2 — a one-year extension.

Part 2:

During this second part of the trial, all participants receive the active vaccine treatment but are still randomly assigned to get either a low or high dose of prasinezumab.

How the clinical trial will test if prasinezumab works

Motor and non-motor symptoms will be tested using the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) total score — after one year, at the end of the first part of the study, to see if the active treatment is more effective than the placebo.

You can read more about how Parkinson’s is measured in this previous blog post.

The trial also has a number of secondary goals, which include both clinical and patient-reported outcomes as well as safety measures. And brain scans will be used to see if the therapy may be slowing the loss of dopamine-producing brain cells — the type of cell that is lost in Parkinson’s.

Finally, technology is playing a role in this trial. Roche’s PD Mobile Application v2. — a smartphone app that includes several motor function tests — is also being used to explore the ability of technology to measure motor abilities. The app will ask participants to perform tests every other day as well as collecting and passive data.

Dr Beckie Port, Research Communications Manager at Parkinson’s UK comments:

“We know that vaccine therapies have the ability to treat conditions like cancer, and the progress in developing a vaccine for Parkinson’s is hugely exciting.

“There is real hope that these kinds of trials will lead to treatments that have the potential to dramatically change how we treat Parkinson’s and enable people to live better for longer. But this it is important that we follow proper clinical trial guidelines to ensure that such therapies are safe and effective in the long term.

“It may be some time before we see a vaccine therapy for Parkinson’s become available. But Parkinson’s UK and research organisations around the world are doing all they can to speed up the delivery of better treatments. We urge people to find out about opportunities to take part in research studies to help get us there faster. Together we can stop Parkinson’s in its tracks.”

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Dr Beckie Port

Dr Beckie Port

2.2K Followers

Research Communications Manager at @ParkinsonsUK. Ex-researcher in oncology and virology.