Modern therapies have transformed care for people with multiple sclerosis (MS). Yet the disease continues to progress in a substantial proportion of patients, even in the absence of relapses. Detecting and treating this gradual worsening of disability remains one of the greatest challenges in MS care. Researchers from the University of Basel, Switzerland, now report on a blood marker that could help track disease progression and monitor treatment response.

Relapses are only part of the disease process in MS. In some patients, physical and cognitive abilities continue to gradually decline even in the absence of relapses. Experts refer to this as progression independent of relapse activity (PIRA). This process develops slowly and is difficult to detect and quantify. A currently available blood test measures neurofilament light chain (NfL), a biomarker that mainly reflects neuroaxonal damage caused by acute inflammatory disease activity. A blood marker that captures the progressive component of the disease has so far been lacking.

“One of the key questions for us was whether progression leaves a different biological fingerprint than inflammation,” says Professor Jens Kuhle from the University of Basel and the Research Center for Clinical Neuroimmunology and Neuroscience (RC2NB) at University Hospital Basel. “If these processes are biologically distinct, we also need biomarkers that reflect different aspects of the disease rather than expecting a single marker to capture everything.”