On Friday, the U.S. Food and Drug Administration (FDA) approved Quest Diagnostics’ Stratify JCV companion diagnostic test in order to reduce the risk for patients who are the most susceptible. JCV, or the John Cunningham Virus, linked to people diagnosed with multiple sclerosis (MS).
Tysabri is a miracle injectable drug used to treat MS patients as well as Crohn’s disease (CD). About 400,000 people have MS in the United States alone, a debilitating disease in which the body attacks its own nervous system, and 50% to 60% of MS patients have JCV, Quest Diagnostics estimates. The JCV is a common virus that many people have been exposed to at some point in their lives, and is generally harmless. However, people with compromised immune systems, such as patients using immunomodulatory therapies like Tysabri, have an increased risk of developing progressive multifocal leukoencephalopathy (PML). PML usually causes death or severe disabilities.
Currently, there is no treatment, prevention or cure for PML, and no way to predict who will develop this dangerous disease.
Many patients who take Tysabri experience improved health, but face an increased risk of contracting a rare and potentially fatal brain infection known as progressive multifocal leukoencephalopathy (PML), which grows from the John Cunningham virus.
Biogen teamed up with Quest Diagnostics to develop an antibody test, which could identify patients whose exposure could put them at higher risk of PML, which causes brain swelling. Stratify is the first test of its kind designed to identify the virus in patients taking Tysabri and was developed by Biogen Idec and Elan.
Quest’s Focus Diagnostic Laboratory will offer the test in the United States.
Doctors can use the results of the blood-based test, combined with the facts about the patient’s medical history, to determine whether they are at risk of developing the brain infection. Other factors that influence a patient’s risk include how long they have been taking Tysabri and whether they have previously taken additional medications that weaken the immune system.
In a separate action, the FDA announced updates to the drug label for Tysabri. The change includes information that testing positive for anti-JCV antibodies is a recently identified risk factor for developing PML in patients treated with Tysabri for MS or CD.
The test is for professional use and by prescription only, and is to be performed only at Focus Diagnostics’ Reference Laboratory.
The label change could add a full $1 billion to 2016 sales of the drug, which Biogen sells in partnership with the Irish company Elan. RBC Capital Markets analyst Michael Yee told the news service that Tysabri could reach $2.5 billion to $3 billion in revenues that year, compared with $1.5 billion to $2 billion without the change.