Expert opinion: Criteria for second-line treatment failure in patients with multiple sclerosis

Objectives: In the management of multiple sclerosis (MS), defining criteria for identification of suboptimal therapy responses and switching treatment is essential to avoid worsening. Despite the lack of a standardised definition, criteria for first-line treatment are well documented in the literature, based on clinical measures or magnetic resonance imaging (MRI) (gadolinium enhancing [Gd+] lesions or new/enlarging T2 lesions) assessed during the first 6-18 months after treatment initiation. However, it is unknown whether the same criteria can be used for second-line treatment failure. Methods: Five regional boards involving 36 French MS experts were convened to discuss published literature regarding criteria for first- and second-line treatment failure, and to identify differences in local therapeutic practices. A national board of 11 experts was subsequently conducted to identify convergences and differences between regions, and to propose second-line criteria for the definition of therapeutic failure. Results: Published information is lacking regarding second-line treatment failure criteria. In light of this, regional differences in current therapeutic practices are justifiable. Due to the risk-benefit ratio of these treatments and limited options for third-line treatments, the authors recommend a different therapeutic approach when assessing second-line treatment failure. The treatment switch for second-line treatment should be informed by confirmed disease progression, after 6 months, or combined clinical and MRI outcomes, but only after at least 1 year of treatment. Conclusions: Experts compared therapeutic attitudes and practices regarding second-line treatment failure between French regions. They identified convergences that were used to propose a national agreement on second-line treatment failure criteria, which should be evaluated in real-life prospective cohorts.