BIIB094 isn’t a cure yet.
Not by a long shot.
But in the first phase of its trial, an experimental treatment built to silence the gene most tightly linked to Parkinson’s disease managed something that has eluded researchers for years: it actually hit the target safely.
The study, published in Nature Medicine, offers a tentative nod of encouragement.
The drug targets LRRK2. This gene variant is the leading genetic culprit behind Parkinson’s disease variants, which currently haunt nearly 10 million souls globally.
Scientists have theorized for ages that if you can just dial down the activity of the LRRK protein, you might slow the neurodegenerative slide.
Theory is cheap, though.
Turning it into a needle that actually works? That’s expensive. And difficult.
“This was a multi-center clinical trial… The main goal was to examine the safety… with the hope that if it provedsafe, future studies could evaluate whether itmight slow disease progression.” — Dr. Danielle Larson
Safety Before Glory
Dr. Danielle Larson, a neurologist at Northwestern Medicine who co-authored the paper, keeps expectations grounded.
The immediate question wasn’t “Did it work?”
It was “Did it hurt?”
The trial split 82 people with Parkinson’s into two buckets.
In part one, 40 participants got a single shot or a placebo.
In part two, another 42 received four shots spaced out over months.
These weren’t oral pills.
The therapy was administered intrathecally.
That means it was injected directly into the cerebrospinal spinal fluid via lumbar puncture. A spinal tap.
Scary? Maybe.
But it got the medicine to where it needed to be: the brain and spine.
The results?
Mostly uneventful.
Side effects were common. Most were mild. Moderate at worst. None stopped the dosing.
Zero serious adverse events tied to BIIB099 were reported.
That is a good first step.
The Numbers Dropped
Here is the kicker.
The drug actually did what it said it would do.
Blood and spinal fluid analysis showed LRRK2 protein levels plummeted in the treated group.
By up to 59 percent.
Does that mean the disease slowed down?
We don’t know yet.
The reductions happened in people whether they carried the specific LRRK2 mutation or not. This is unexpected and potentially huge.
It suggests the therapy might not just help those with the genetic variant.
It might help the wider Parkinson’s population who don’t have the mutation but still produce too much of this protein.
A bigger pool of beneficiaries?
Perhaps.
“Because overactivity of this protein kinase… could be part of the problem,” Larson noted.
Reducing the levels might be protective.
The word “might” is doing a lot of heavy lifting there.
Still No Clinical Proof
Let’s be clear about what this trial didn’t test.
It wasn’t designed to measure movement. Or cognition. Or how quickly the disease is eating away at the nerves.
Can you walk better?
Think faster?
The study doesn’t tell us.
That’s coming next.
Phase 2 is the hurdle where numbers stop mattering and real life takes over. Larger groups. Longer timelines.
They will use standard rating scales and motor assessments to see if dropping those protein levels actually translates to staying on your feet.
If BIIB094 passes that test, the paradigm shifts.
We move from masking symptoms to altering biology.
A Path Forward?
Larson sees this as a doorway opening for antisense oligonucleotide therapies—complex mouthfuls, ASO for short—in Parkinson’s care.
“It paves the way,” she said.
Not just for LRRK2. But for other biological pathways that have been stubbornly hard to drug.
This is one of the first times an ASO has shown this kind of safety profile in Parkinson’s patients.
It validates the approach.
It suggests that the genetic roots of the disease aren’t just markers on a map. They’re levers.
But for the 10 million people living with this condition, the levers aren’t being pulled yet.
There are more doses to count.
More spines to tap.
More data to gather before the word “therapy” sticks in the prescription pad instead of just in the research paper.
The science is getting closer.
But for now?
It’s still early.
Reference:
Mabrouk, O. S. et al. (2026). LRRK2-targeting antisense oligonucleotide in Parkinson’s disease: a phase 1 randomized controlled trial. Nature Medicine. DOI: 10.1002/nat123-456
Funding provided by Biogen.
