Disease-related biomarkers provide information about whether a disease is imminent, whether the disease already exists or how a disease will likely develop in individual cases. For many years, multiple sclerosis research has therefore been looking for a valid biomarker that can provide clues about the course of the disease and a response to therapy. So far, magnetic resonance imaging and the number of lesions are an important diagnostic and predictive biomarker – unfortunately, the predictive value is lost in the course of the disease in MRI, and its use is logistically complex, which is why it would be desirable to have an easy-to-determine blood value that can serve as a biomarker for MS.
A promising candidate is the protein neurofilament light in the serum of patients, although the blood draw is simple, the determination is complicated and based on a complex process that has not yet been widely adopted in routine diagnostics. Nevertheless, it is worth looking at this parameter: Neurofilament light (the light chain of the neurofilament protein) is a marker for neurodegeneration, which is increased in nerve cell death of any cause. Accordingly, patients with dementia diseases but also with head-brain displacements have elevated values, but also MS patients, in whom the disease leads to axonal damage. Thus, neurofilament light in the serum shows a good correlation with the number and activity of inflammatory lesions in MRI and also correlates with the extent of brain atrophy in MRI. An efficient drug therapy for multiple sclerosis leads to a reduction in serum neurofilament light levels, so that in principle the effect of MS drugs can be monitored.
A significant problem is that the increase in Nfl is not specific to MS and that with increasing age the Nfl values in the serum also increase.
At the ECTRIMS Congress, the Basel working group around Jens Kuhle presented an age-standardized determination of serum Nfl values – in my view an important step towards routine use of this biomarker. With the help of age standardization, a tool is now available that can also measure neuronal damage in MS regardless of age and assign patients to certain MS therapies. With the help of these age-standardized values, it could be predicted which patients were stable in the following year and which continued to show signs of disease activity. The early availability of this biomarker would also be desirable in view of the discussion about prodromal MS.
