A study conducted by the Clinical Neuroimmunology Research Group of the Vall d'Hebron Research Institute (VHIR) and the Multiple Sclerosis Center of Catalonia (Cemcat) has identified the concentration of serum neurofilament light chains (sNfL) as a biomarker that predicts the long-term involvement of patients with progressive multiple sclerosis. The study finds that patients with levels of more than 10.2 picograms per milliliter (pg/ml) have a higher degree of disability a decade later than those with a lower level.

sNfL was already used as a biomarker to predict flares in people with relapsing-remitting multiple sclerosis, but its usefulness in patients with the progressive variant was unknown. The first investigations in this line had been unsuccessful because they had looked at it over the short and medium-term. The study published in the Journal of Neurology, Neurosurgery, and Psychiatry has analyzed the evolution of patients for more than 14 years. "The relationship between sNfL levels and the disease progression becomes clearer as more time passes", explains Dr. Manuel Comabella, from the Clinical Neuroimmunology Service at Vall d'Hebron University Hospital, principal investigator of the Clinical Neuroimmunology group at VHIR and head of the Cemcat laboratory. Cemcat is one of the state reference services for the multiple sclerosis care process.

To conduct the study, 51 patients who had participated in a clinical trial from 1998 to 2001 and who had undergone periodic check-ups were monitored. The extended Kurtzke disability status scale (EDDS) was used to measure the patients' impairment and sNfL levels were measured with a state-of-the-art Simoa-type analyzer.

A real-time snapshot of the central nervous system damage

The study showed that, apart from having a constant above 10.2, any change in sNfL level was also an indicator of increased long-term patient impairment. Furthermore, if an analysis was made of the temporal evolution of sNfL, it corresponded significantly with the EDDS scale. "This tells us that the neurofilament takes a real-time snapshot of the damage present in the patient's central nervous system and thus its evolution can be deduced", explains Dr. Xavier Montalban, head of the Clinical Neuroimmunology Service at Vall d'Hebron Hospital, head of the Clinical Neuroimmunology research group at VHIR and director of Cemcat.

Multiple sclerosis is an autoimmune disease that affects the brain and central nervous system. In Spain there are between 80 and 100 people with sclerosis per 100,000 inhabitants, which means that there are about 55,000 patients. Between 10% to 15% of these suffer from the primary progressive variant in which the onset of symptoms takes place in a linear and irreversible manner. On the other hand, patients with the relapsing-remitting type experience flares that appear for a period of time and then improve partially or completely. Some patients with the relapsing-remitting type progress to a mixed variant called secondary progressive, which is characterized by progressive neurological worsening, whether or not related to the flares.

Currently, the study of sNfL levels is used to alert patients with relapsing-remitting type to the proximity of a new flare, with the new study it is hoped that it can also identify patients with progressive sclerosis with worse prognosis so that their physicians can start preventive treatments as soon as possible