Approach 5 of 6
Treat the inherited causes
Can we treat the genes behind some Parkinson's?
44 steps since 1998. 17 moved us forward. A large trial of an LRRK2 drug, LUMA, did not slow Parkinson's in 2026. Smaller trials in people who carry the gene report from 2027. As of Oct 2026
Facts on this page checked 18–20 Oct 2026
Each dot is one step in this approach: a discovery, a new tool or a trial, by the year it started.
- 17 moved us forward
- 2 waiting for results
- 18 still open
- 1 overtaken by better ideas
- 6 dead ends
Where it stands
- How far it has got
- Step 3 of 5 · Testing whether it helps
- Has it slowed Parkinson's?
- Not yet shown
- Tried and did not work
- 2 trials
- Next result
- Mar 2027BEACON · Phase 2
The idea in brief
In a small share of people, a change in one gene is the main cause of their Parkinson's. If a drug could treat that cause directly, it might slow the disease.
The best-known example is LRRK2. In 2004, scientists found that changes in this gene cause Parkinson's (The LRRK2 gene). The gene makes an enzyme, a protein that does a job in the cell. In some people the enzyme is overactive.
Drug makers built drugs to turn it down. Some are tablets that block the enzyme. Another kind is injected into the spinal fluid and tells cells to make less of it.
All the trials on this page aim at LRRK2. Trials for other genes sit on other pages, as explained below.
Is my Parkinson's genetic?
Most Parkinson's is not inherited. In a large US testing programme, about one in eight people carried a change in one of seven genes linked to Parkinson's (PD GENEration: free genetic testing). Most carried none.
The change in LRRK2 is found in about one in a hundred people who have no family history of Parkinson's (How often LRRK2 carriers get Parkinson's). Many carriers never get Parkinson's, and studies differ on how many do. The other main gene is GBA. Trials for people with a GBA change are on the Help cells clean up page. Drugs that lower the protein made by the SNCA gene are on Clear the bad protein.
Genetic testing is a conversation for your neurologist or a genetic counsellor.
How we got here
- Twin study · 1999
- The LRRK2 gene · 2004
- How often LRRK2 carriers get Parkinson's · 2008
- LRRK2 drugs and the lungs · 2015
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
4 trials
-
DNL201 · an early LRRK2 blocker
Replaced by a newer approach
The first LRRK2 drug tested in people, in 122 healthy volunteers and 28 patients. It was well tolerated and hit its target. Benefit was not tested.
-
DNL151 safety studies · BIIB122 (then called DNL151), a tablet that blocks LRRK2
Passed this stage
In 184 healthy volunteers and 36 people with Parkinson's, it was well tolerated for 28 days and lowered LRRK2 markers. Benefit was not tested.
-
LRRK2 antisense drug · BIIB094, an injection into the spinal fluid that makes cells produce less LRRK2
Did not work
It lowered LRRK2 protein in an 82-person safety trial. Biogen stopped it for business reasons, not because it failed. It was never tested for benefit.
-
LUMA · BIIB122, an LRRK2 drug
Did not work
Cut its blood target by over 90% in 648 people, but did not slow Parkinson's. A small spinal-fluid test hinted that less drug reached the brain.
Still to come
2 trials · dates are expected, not promised
The next result is due in Mar 2027, from BEACON. The largest trial still to report, NEULARK, is expected in Dec 2027.
-
BEACON · BIIB122, in people with an LRRK2 gene change
Result due Mar 2027
Will tell us whether the drug is safe in LRRK2 carriers and changes cell markers. It cannot show whether it slows Parkinson's.
Who: 50 adults with an LRRK2 gene change · Last checked 19 Oct 2026
Details and sources: BEACON Check if it is recruiting: BEACON
-
NEULARK · NEU-411, a second LRRK2 blocker
Result due Dec 2027
Will tell us whether blocking LRRK2 helps when people are picked by a test, not only by diagnosis. It uses a phone-app score at one year.
Who: About 150 adults with early Parkinson's, picked by a test for LRRK2-driven disease · Last checked 18 Oct 2026
Details and sources: NEULARK Check if it is recruiting: NEULARK
In words
Of the 6 trials in people, 2 did not work, 1 passed its first stage, 1 was replaced by newer approaches, and 2 have results due. The first is due in Mar 2027; the largest, NEULARK, in Dec 2027.
What the dead ends taught us
- Hitting the target is not the same as slowing Parkinson's. The drug in LUMA switched off its blood target but did not slow Parkinson's. A small spinal-fluid test hinted that less drug reached the brain. (LUMA; DNL151 safety studies; DNL201)
- "Safe" is not the same as "works". Early trials showed the drugs were well tolerated and hit their targets. They did not test whether Parkinson's slowed. The trial for carriers, BEACON, measures safety and markers, so it cannot prove benefit. (DNL201; DNL151 safety studies; BEACON)
- Stopped is not the same as failed. The spinal-fluid drug in LRRK2 antisense drug lowered LRRK2 protein safely. Its company dropped it for business reasons, not because it failed. A carrier trial inside LUMA ended early with no answer, because very few people joined. (LRRK2 antisense drug; LUMA)
- Gene findings need replication in thousands of people. Several genes named as causes did not hold up when larger studies looked again. (UCHL1 I93M (PARK5); GIGYF2 and EIF4G1: disputed genes; HTRA2/Omi (PARK13) did not hold up; DNAJC13 and TMEM230: disputed genes)
Most drugs tested against any brain disease do not work, and each one that fails rules something out.
What it would mean for you
If an LRRK2 drug works, it would slow Parkinson's down. It would not bring back brain cells that are already lost. It would be aimed first at people with an LRRK2 gene change, a small group.
In monkeys, LRRK2 drugs changed lung cells. The change reversed when the drug stopped, and breathing tests were normal (LRRK2 drugs and the lungs). We do not know yet if this holds in people over long use.
BEACON is expected to report in Mar 2027, and NEULARK in Dec 2027. These dates are expected, not promised. Trials often run late. Even with a good result, a larger trial and approval would follow.
Should I try this now?
No. No LRRK2 drug can be prescribed outside a trial. Do not buy genetic tests online without counselling. The results are hard to read alone. A neurologist can advise on whether testing makes sense for you.
Can I take part?
These trials look for people with an LRRK2 gene change, or people with early Parkinson's who are picked by a test for LRRK2-driven disease. Each trial sets its own rules. Ask your neurologist.
Related approaches
Sources, and the same lanes for researchers
This page is built from 44 research landmarks. Each has its own sources; follow "Details and sources" on any trial. Facts were checked 18–20 Oct 2026. The summary was written on 22 Oct 2026.
- LRRK2 (19 landmarks)
- Genetic architecture (25 landmarks)
- See these lanes on the full map
How this project checks its facts · Report an error on this page