The outlook for an experimental Parkinson’s disease drug dimmed on Thursday with the announcement that it had failed a key clinical trial.
Developed through a partnership Denali Therapeutics and Biogen, the drug is designed to inhibit an enzyme tied to one of the most common genetic drivers of Parkinson’s: a gene called LRRK2. When this gene mutates, it causes the waste disposal systems in cells to malfunction, leading to the buildup of toxic proteins that damage and destroy neurons.
In 2022, Biogen and Denali kicked off what would ultimately become a nearly 650-person trial that pitted their drug against a placebo. The companies are now saying this mid-stage study showed the drug — codenamed BIIB122 — was not significantly better at slowing the disease progression, as measured by a well-known scale clinicians use to assess how Parkinson’s is affecting a patient’s movement and daily life.
BIIB122 also didn’t benefit patients on the trial’s secondary goals. While some “exploratory” analyses signaled it was engaging with and hindering that harmful enzyme, the overall results convinced Biogen and Denali not to further develop the drug for “idiopathic” Parkinson’s. Denali, though, plans to continue independently running a separate experiment evaluating the drug in Parkinson’s patients who carry a disease-causing LRRK2 variant.
More detailed findings from the failed trial will be presented at an upcoming medical meeting.
“While these are not the results we hoped for, these data provide important information to the Parkinson’s community,” Diana Gallagher, Biogen’s head of neurodegeneration clinical development, said in a statement.
On Wall Street, analysts have viewed BIIB122 as a higher-risk program and given it little, if any, weight in their valuations of Biogen and Denali. They argue shareholders of each company are more focused on other research projects, such as Biogen’s pending lupus data and Denali’s work in Alzheimer’s disease.
Among Biogen investors, “we believe expectations were virtually zero,” wrote RBC Capital Markets analyst Brian Abrahams. The company “did not actively talk it up (and had bucketed it as high risk), we rarely received questions about it, and we did not incorporate it into our model.”
Biogen shares were up a little over 1% by mid-morning Friday, whereas Denali's had fallen about 5%.
The companies began collaborating in the summer of 2020, through a cash and equity deal worth more than $1 billion.
Not three years later, there were signs Biogen’s confidence in BIIB122 was waning. As part of a broader reshuffling of research priorities, the company decided to scrap a late-stage trial of the drug because of its complexity and “long timeline.” The study was set to run until 2031.
