What treatments target alpha-synuclein in Parkinson's?

Several approaches are being tested: antibody infusions that try to clear the protein (prasinezumab, and the discontinued cinpanemab), small-molecule pills that aim to stop the clumping (minzasolmin), and an active vaccine that trains the immune system to make its own antibodies (UB-312). You can see each program and its current phase on the drug pipeline tracker.

Has any alpha-synuclein drug been shown to work?

Not yet. Cinpanemab failed its Phase 2 trial in 2021, and prasinezumab missed its main goals in both of its trials, though one showed a possible signal in a subgroup worth pursuing. No alpha-synuclein therapy has hit its pre-specified primary goal in a large controlled trial. The theory is strong but has been hard to prove, so be cautious of any 'breakthrough' claim.

Why have alpha-synuclein drugs been so disappointing?

There are several possible reasons: the treatments may be given too late, after too much damage is done; clearing the protein from outside the cell may not reach the clumps that matter most; or alpha-synuclein may not be the whole story of the disease. The repeated setbacks are part of how science narrows in on what actually works, and several programs remain active.

Alpha-Synuclein and Parkinson's: The Protein at the Center of the Search for a Cure

One word keeps coming up in Parkinson's research: alpha-synuclein. It is the protein most scientists believe sits at the heart of the disease, and it is the target of many of the most ambitious attempts to slow Parkinson's rather than just treat symptoms. It is also the source of some of the field's most painful disappointments.

What Alpha-Synuclein Actually Is

Alpha-synuclein is a normal protein found throughout the healthy brain, where it helps nerve cells communicate. The problem in Parkinson's is not the protein itself but what happens when it misfolds: it changes shape, sticks to other copies of itself, and forms clumps that build up inside brain cells as deposits called Lewy bodies. The leading theory is that these clumps are toxic, spread from cell to cell, and contribute to the death of dopamine-producing neurons. If that is right, stopping or clearing the clumping might slow the disease. See disease-modifying vs symptomatic trials.

The Ways Researchers Are Trying to Target It

Antibodies that clear the protein: prasinezumab (Roche and Prothena) is the most advanced, but neither its PASADENA nor its larger PADOVA trial hit its main goal with statistical significance, though PADOVA showed a possible subgroup signal; an earlier antibody, cinpanemab (Biogen), failed its Phase 2 in 2021. Pills that stop the clumping: minzasolmin (UCB and Novartis) is a small-molecule pill tested in the Phase 2 ORCHESTRA trial. A vaccine: UB-312 (Vaxxinity) prompts the immune system to make its own antibodies and is at the earliest human stage. See all programs on the drug pipeline tracker.

Why This Has Been So Hard

The theory is strong but the track record is humbling. Cinpanemab failed; prasinezumab missed its main goals in both trials. Possible explanations: treatments given too late, clearing the protein from outside the cell may not reach the clumps that matter, or alpha-synuclein may not be the whole story. No alpha-synuclein drug has hit its pre-specified primary goal in a large controlled trial, so be cautious of any "breakthrough" claim. See what the world is doing about Parkinson's and gene and cell therapy.

Frequently Asked Questions

What is alpha-synuclein and why does it matter in Parkinson's?: Alpha-synuclein is a normal protein found throughout the healthy brain, where it helps nerve cells communicate. In Parkinson's it misfolds, sticks to other copies of itself, and forms clumps that build up inside brain cells as deposits called Lewy bodies. The leading theory is that these clumps are toxic and contribute to the death of dopamine-producing neurons, which is why so much disease-modifying research targets this protein.
What treatments target alpha-synuclein in Parkinson's?: Several approaches are being tested: antibody infusions that try to clear the protein (prasinezumab, and the discontinued cinpanemab), small-molecule pills that aim to stop the clumping (minzasolmin), and an active vaccine that trains the immune system to make its own antibodies (UB-312). You can see each program and its current phase on the drug pipeline tracker.
Has any alpha-synuclein drug been shown to work?: Not yet. Cinpanemab failed its Phase 2 trial in 2021, and prasinezumab missed its main goals in both of its trials, though one showed a possible signal in a subgroup worth pursuing. No alpha-synuclein therapy has hit its pre-specified primary goal in a large controlled trial. The theory is strong but has been hard to prove, so be cautious of any 'breakthrough' claim.
Why have alpha-synuclein drugs been so disappointing?: There are several possible reasons: the treatments may be given too late, after too much damage is done; clearing the protein from outside the cell may not reach the clumps that matter most; or alpha-synuclein may not be the whole story of the disease. The repeated setbacks are part of how science narrows in on what actually works, and several programs remain active.