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FDA Backs Further Development of Blood Biomarker, Neurofilament Light, for Clinical Trials in Progressive MS

June 25, 2021

  • The regulatory agency’s Letter of Support will stimulate more studies that advance development and validation of this biomarker to speed clinical trials
 A major milestone in the goal of increasing the number and speed of clinical trials in progressive multiple sclerosis was recently achieved when the International Progressive MS Alliance received a Letter of Support from the U.S. Food and Drug Administration (FDA). The Letter encourages the exploration and development of further studies around a molecule in blood serum or plasma -- neurofilament light chain (NfL) -- as a potential rapid indicator of the value of an experimental therapy in early trials involving people with progressive MS.
NfL is a fragment in the debris that enters the spinal fluid and blood when nerve wires (axons) are damaged. Studies of NfL have been underway to better define how this biomarker may be employed to help detect and predict disease activity and response to treatments, not only in MS but in other disorders. NfL may reflect ongoing disease pathology and may be more responsive to the effects of treatments than traditional imaging (MRI) outcomes in early phase trials.
This is the first time the FDA has provided a Letter of Support for further research of any MS-specific biomarker for use in clinical trials. Because further steps and research are needed to gain qualification of NfL as an outcome measure, this Letter can spur further development by signaling to industry and other researchers that drug regulators are aware of the evidence supporting this biomarker. The Alliance has also submitted support materials to the European Medicines Agency to request a similar Letter from them.
The FDA’s Letter of Support resulted from an application that included a review of published research results on NfL that was compiled by the Alliance’s Fluid Biomarkers Implementation Team, a panel that includes experts from the pharmaceutical/biotech industry, academic research and people living with progressive MS. The team had previously published recommendations outlining evidence and priority research for developing NfL as a biomarker for progressive MS.
“Receiving this Letter of Support is a critical step that signals to industry sponsors and academic researchers the potential value of including serum neurofilament light as an exploratory outcome measure in clinical trials focusing on progressive MS,” said Dr. Robert J. Fox, Vice Chair of the Alliance’s Scientific Steering Committee and senior author of the Biomarkers Implementation Team paper. “Having a simple blood test to quickly track the potential benefits of experimental therapies would be an enormous step forward for people with progressive MS, for whom there are too few therapies.”
The Alliance is also investing in other initiatives to develop biomarkers of therapies for progressive MS, and recently announced funding 19 new Research Challenge Awards to improve the understanding of mechanisms that drive progression, an area where the current lack of knowledge is hindering treatment development.

About Multiple Sclerosis

Multiple sclerosis is an unpredictable disease of the central nervous system. Currently there is no cure. Symptoms vary from person to person and may include disabling fatigue, mobility challenges, cognitive changes, and vision issues. An estimated 1 million people live with MS in the United States. Early diagnosis and treatment are critical to minimize disability. Significant progress is being made to achieve a world free of MS.

About the National Multiple Sclerosis Society

The National MS Society, founded in 1946, is the global leader of a growing movement dedicated to creating a world free of MS. The Society funds cutting-edge research for a cure, drives change through advocacy and provides programs and services to help people affected by MS live their best lives. Connect to learn more and get involved:, Facebook, X, formerly known as Twitter, Instagram, YouTube or 1-800-344-4867.


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