Approach 2 of 6
Clear the bad protein
Can we stop the toxic clumps forming and spreading?
45 steps since 1997. 16 moved us forward. One final-stage trial, of about 900 people, runs to 2029. Four other drugs did not work or were dropped. The rest are early safety tests. As of Oct 2026
Facts on this page checked 18–22 Oct 2026
Each dot is one step in this approach: a discovery, a new tool or a trial, by the year it started.
- 16 moved us forward
- 6 waiting for results
- 18 still open
- 5 dead ends
Where it stands
- How far it has got
- Step 4 of 5 · Final large trials
- Has it slowed Parkinson's?
- Not yet shown
- Tried and did not work
- 4 trials
- Next result
- Dec 2026EXIST · Phase 2
The idea in brief
In Parkinson's, a protein called alpha-synuclein folds into the wrong shape. The misshapen protein sticks together into clumps inside brain cells. Scientists think these clumps harm the cells, and may spread from one cell to the next.
Two clues point to this protein. In 1997, scientists found that the clumps seen in Parkinson's brains, called Lewy bodies, are made mostly of it. In 2003, they found that people born with extra copies of its gene get Parkinson's.
So researchers are trying two things. Some drugs try to catch the clumps and stop them spreading. These are antibodies (lab-made immune proteins), vaccines and pills. Other drugs try to make cells produce less of the protein in the first place.
How we got here
What has been tried
Each row is one trial in people. Its dot shows how it turned out, using the same key as the chart above.
Results already in
8 trials
-
PD01A vaccine · a vaccine against the protein
Passed this stage
Safe in 24 people with early Parkinson's, and their bodies made antibodies. Too small to show whether it slows the disease.
-
SPARK · cinpanemab, an antibody drug
Did not work
Made no difference at any dose in 357 people. The company stopped work on it in February 2021.
-
ORCHESTRA · minzasolmin, a pill
Did not work
A pill meant to stop the protein folding the wrong way. It did not help in about 500 people.
-
Buntanetap · a pill
Did not work
No overall change in 523 people after 6 months. The company points to benefit in smaller groups of patients, which is not proof.
-
UB-312 vaccine · a vaccine against the protein
Mixed or early results
Safe, but antibodies reached the fluid around the brain in only 5 of 13 people. No next trial has been announced.
-
Anle138b · a pill to stop clumps forming
Mixed or early results
Safe in early tests. Its next trial is in a related disease, MSA, not in Parkinson's.
-
PASADENA and PADOVA · prasinezumab, an antibody drug
Mixed or early results
Narrowly missed its main goal twice, in 316 and then 586 people. Hints of slower decline led to the much larger PARAISO trial.
-
ION464 · a drug that makes cells produce less of the protein
Did not work
Tested only in MSA, a related disease. The company dropped it in 2025, so it will not give an answer for Parkinson's.
Still to come
6 trials · dates are expected, not promised
The next result is due in Dec 2026, from EXIST. The largest trial still to report, PARAISO, is expected in Jun 2029.
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EXIST · exidavnemab, an antibody drug
Result due Dec 2026
A safety study that finished in August 2026. It checks safety, not whether the drug slows Parkinson's.
Who: People with Parkinson's or MSA · Last checked 19 Oct 2026
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VacSYn · ACI-7104, a vaccine
Result due Jun 2028
Everyone given the vaccine so far made antibodies. The first part checks safety; a larger second part is planned.
Who: People with early Parkinson's · Last checked 19 Oct 2026
Details and sources: VacSYn Check if it is recruiting: VacSYn
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PARAISO · prasinezumab, an antibody drug
Result due Jun 2029
The main answer. It will show whether prasinezumab slows Parkinson's over at least 2 years.
Who: About 900 people with Parkinson's · Last checked 18 Oct 2026
Details and sources: PARAISO Check if it is recruiting: PARAISO
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ALN-SNCA · a drug that makes cells produce less of the protein
Result due Jun 2029
The first safety test in people with early Parkinson's.
Who: People with early Parkinson's · Last checked 19 Oct 2026
Details and sources: ALN-SNCA Check if it is recruiting: ALN-SNCA
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LY3962681 · a drug that makes cells produce less of the protein
Result due Jul 2030
A safety test. People with Parkinson's must first have a positive spinal-fluid test for the protein.
Who: Healthy volunteers, and people with Parkinson's who test positive for the protein · Last checked 19 Oct 2026
Details and sources: LY3962681 Check if it is recruiting: LY3962681
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PreCoDe · prasinezumab, an antibody drug
Result due Dec 2030
Tests whether the drug slows memory and thinking problems in people with a GBA gene change. Not yet started.
Who: People with Parkinson's and a GBA gene change · Last checked 22 Oct 2026
Details and sources: PreCoDe Check if it is recruiting: PreCoDe
In words
Of the 14 trials in people, 4 did not work, 1 passed its first stage, 3 had mixed or early results, and 6 have results due. The first is due in Dec 2026; the largest, PARAISO, in Jun 2029.
What the dead ends taught us
- Small differences in a drug matter. Two antibodies aimed at the same protein gave different results. Cinpanemab did nothing; prasinezumab came close. (SPARK; PASADENA and PADOVA)
- Working in the lab is not the same as working in people. A pill that stopped the protein misfolding in the lab did not help patients. We do not yet know if the dose, the timing or the idea was wrong. (ORCHESTRA)
- A benefit in a small group is a clue, not proof. When a company reports benefit only in some patients, that needs its own trial. (Buntanetap)
- Trials now check for the target first. Newer trials use a spinal-fluid test to make sure people really have the misfolded protein before they join. (A spinal-fluid test can detect the misfolded protein)
Most drugs tested against any brain disease do not work. Each one that fails rules something out and shapes the next trial.
What it would mean for you
If one of these drugs works, it would slow Parkinson's down. It would not bring back brain cells that are already lost. It would probably help most if started early.
The drugs are given by drip or injection. Some of the protein-lowering drugs are injected into the spinal fluid.
The biggest trial, PARAISO, is expected to report in Jun 2029. Even with a good result, approval would take further time after that. The protein-lowering drugs are still at the first safety step.
Should I try this now?
No. None of these drugs can be prescribed outside a trial. Be wary of supplements or "detox" products that claim to clear this protein. None has been shown to work.
Can I take part?
These trials mostly look for people with early Parkinson's. Some look for people with a particular gene change (GBA), or ask for a spinal-fluid test first. Each trial sets its own rules.
Related approaches
Sources, and the same lanes for researchers
This page is built from 46 research landmarks. Each has its own sources; follow "Details and sources" on any trial. Facts were checked 18–22 Oct 2026. The summary was written on 22 Oct 2026.
- Synuclein misfolding & spread (31 landmarks)
- Synuclein lowering (15 landmarks)
- See these lanes on the full map
How this project checks its facts · Report an error on this page