Our view on inflammation and stroke

Blocking immune cells as an approach against brain injury

By Jacob Elkins
Head, Neuroinflammation Development

September 8, 2016

Predicting when a stroke will happen, and to whom, is virtually impossible. Every one of us has a myriad of variables that affect our chances of stroke including genetics, lifestyle, and environmental factors. One constant remains: stroke kills 1 out of 20 Americans every year.

Why is a stroke so debilitating?
An acute ischemic stroke happens when a blood vessel becomes clogged, cutting off blood flow to the brain. Our brain cells stop functioning after 60-90 seconds without oxygen, and a mere 3 hours without oxygen may result in irreversible brain damage.

When acute ischemic stroke hits, literally every minute counts. Rapid restoration of blood flow to the affected area in the brain is critical. Currently, there’s only one drug that is FDA-approved for the treatment of acute ischemic stroke that is a tissue plasminogen activator (tPA), which breaks down the blockage, but must be administered within 3 hours.

Unfortunately, stroke patients typically don’t make that window. Unlike a heart attack, most patients are less aware that they are experiencing a stroke and don’t seek medical attention right away. In addition, once in the ER, patients must undergo a CT scan to see what type of stroke they’re having and whether they are eligible for tPA. All of this takes precious time.

Our view on inflammation and brain injury
At Biogen, we’re investigating a potential treatment for stroke that can be used outside of this 3-hour window. There’s a compelling body of literature detailing the role of inflammation in the progression of brain damage after stroke. Our investigations focus on how to deal with this immune reaction in the brain. Our hypothesis is that when immune cells cross into the brain, they further stress the already suffering brain cells (neurons), causing them to release chemicals that lead to further neural damage. It’s this persistent inflammatory cascade that stands in the way of effective recovery.

As a neurologist that has worked with both stroke and MS patients, I was very familiar with natalizumab.

New potential approach to address stroke
We conducted a proof-of-concept trial to further investigate natalizumab in stroke and the results were encouraging: a single dose of natalizumab resulted in functional and cognitive improvement of patients, at 30 and 90 days after the stroke. Additionally, the data we collected supported that we could administer natalizumab up to 9 hours post stroke. However, we did not see a similar benefit on the MRI scans as we had expected.  This may have been related to the fact that some types of inflammation can be damaging even though they are not readily detected by MRI .

Stroke remains a devastating, and unfortunately, rather common condition. In the future through additional research we aim to confirm our findings and to address other factors, for example whether it’s useful to give a higher dose. The clinical results and extended window for treatment warrants further studies with natalizumab in the context of stroke  

Learn more about neurology research at Biogen


Magnetic resonance image of arteries in the brain.

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