Tysabri Lawsuit Claims Manufacturer Delayed PML Brain Test To Maximize Profits

The makers of the multiple sclerosis (MS) drug Tysabri are being accused of delaying the development of a test that may have helped identify patients who were more susceptible to a severe and potentially deadly brain infection linked to the drug’s use, known as progressive multifocal leukeoencephalopathy (PML)

Andrew Nelson, of New York, filed an amended complaint (PDF) against Biogen Inc. and Elan Pharmaceuticals in federal court in New Jersey on June 13, updating a lawsuit filed earlier to add claims that the drug makers had access to a test that could detect the virus responsible for users developing PML from Tysabri as early as 2006.

Progressive multifocal leukeoencephalopathy (PML) is a rare and deadly brain infection that has been linked to several different immunosuppressant drugs, including Tysabri. It is believed to occur when the drug disables the immune system enough for the JC virus, a strain of paopvavirus, to take hold. Estimates indicate that about 50% to 60% of the population has contracted the JC virus.

Did You Know?

Millions of Philips CPAP Machines Recalled

Philips DreamStation, CPAP and BiPAP machines sold in recent years may pose a risk of cancer, lung damage and other injuries.

Learn More

According to the lawsuit, Nelson began treatment with Tysabri in January 2007, and was diagnosed with PML in 2010. He indicates that not only did the company fail to warn at the time about the link between Tysabri and brain infections, but indicates that the company may have been sitting on a test that could have helped users detect the JC virus and determine whether they are at risk for PML while taking Tysabri.

Nelson survived PML, but has been left severely debilitated from the brain infection.

The complaint, originally filed several years ago, was recently allowed to be amended after discovery in September 2015 that a licensing agreement between Biogen and the National Institutes of Health showed that the company received JC virus detection technology in 2006. The JC virus test could detect antibodies in those who carried the virus, which may be able to help determine which patients are more at risk of PML.

However, the company did not release a commercial version of the test until 2012, which Nelson’s lawsuit says was motivated by financial reasons, as the company was allegedly attempting to develop their own version instead of using the existing technology, suggesting that the company placed its desire for profits ahead of patient safety.

“If Defendants had acted reasonably in their efforts to develop and commercialize a JC virus antibody assay, Mr. Nelson would have had a JC virus antibody assay available to him,” the lawsuit notes. “Mr. Nelson’s physicians would have tested Mr. Nelson for the JC virus antibodies, and he would have tested positive. With a positive test result, Mr. Nelson and his physician would have known Mr. Nelson was at a higher risk of developing PML and would have conducted a more meaningful risk-benefit discussion regarding Tysabri as a treatment option.”

Tysabri (natalizumab) is an intravenous injection given every 28 days to treat multiple sclerosis (MS) and Crohn’s disease. Manufactured by Biogen Idec Inc. and marketed with Elan Corp PLC, Tysabri has been shown to prevent relapse, cognitive decline and vision loss associated with MS.

Shortly after the drug was introduced in 2004, a Tysabri recall was issued after cases of PML were identified, including at least two deaths. The medication was re-introduced in 2006, with stricter guidelines for usage and more prominent warnings about the possible PML risks associated with Tysabri.

Hundreds of cases of PML have been linked to Tysabri, and many of those patients have died. Nelson’s claim is one of a number of Tysabri lawsuits filed on behalf of patients and family members of individuals who died, alleging that the manufacturer has failed to adequately warn consumers or the medical community about the potential risk of PML from Tysabri side effects.


  • StephanieJuly 17, 2016 at 3:10 pm

    How many death from Tysabri have been reported since 2014? This is when I lost my mother from this drug

"*" indicates required fields

Share Your Comments

I authorize the above comments be posted on this page*

Have Your Comments Reviewed by a Lawyer

Provide additional contact information if you want an attorney to review your comments and contact you about a potential case. This information will not be published.

NOTE: Providing information for review by an attorney does not form an attorney-client relationship.

This field is for validation purposes and should be left unchanged.