The prognostic involvement of CHI3L1 in clinically isolated syndromes is further studied. Serum CHI3L1 levels are increased by the effect of glatiramer acetate treatment. Non-responder patients to interferon-beta treatment have increased serum CHI3L1 levels. Results may suggest a role for CHI3L1 as an interferon-beta treatment response biomarker in RRMS patients.