To accelerate the development of novel therapies targeting progression in multiple sclerosis (MS), quantifiable and objective biomarkers that reflect the non-inflammatory component of MS pathology are needed. In recent years, several fluid biomarkers have demonstrated clinical relevance in the relapsing-remitting space, useful for MS diagnosis and prognosis as well as for the assessment of therapy response. Charlotte Teunissen, PhD, VU University Medical Center Amsterdam, The Netherlands, discusses the importance of developing biomarkers that reflect axonal damage, a process responsible for irreversible progression in MS, which can be used to monitor the effectiveness of therapies for progressive disease. This interview took place at the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) congress 2021.