Quest Diagnostics STRATIFY JCV First FDA Market Authorized Antibody-based Blood Test to Help Stratify PML Risk in Multiple Sclerosis Patients

Quest Diagnostics (NYSE: DGX) today announced that the U.S. Food and Drug Administration has granted a de novo classification petition to its STRATIFY JCV™ Antibody ELISA testing service. STRATIFY JCV is the first blood test to be FDA market authorized for the qualitative detection of antibodies to the polyomavirus JC virus for stratifying risk for progressive multifocal leukoencephalopathy, an infrequent but serious brain infection, in patients with multiple sclerosis receiving TYSABRI® (natalizumab), a highly effective therapy for relapsing forms of MS.

The market authorization follows FDA approval today of a product label change for TYSABRI. The new label identifies JCV antibody status as a PML risk factor; other risk factors include duration of treatment with TYSABRI and prior immunosuppressant therapy use.

STRATIFY JCV was developed under an exclusive collaboration for the United States market with Biogen Idec (NASDAQ: BIIB), co-manufacturer with Elan Corporation, plc (NYSE: ELN) of natalizumab. The test employs technology licensed from Biogen Idec, and is exclusively offered through Quest Diagnostics' Focus Diagnostics laboratory in the United States. It is based on a test validated and performed by Focus Diagnostics in clinical trials.