Decision-Making for Switching Disease-Modifying Therapies in Multiple Sclerosis

Introduction to Switching DMTs

The decision to switch disease-modifying therapies (DMTs) in multiple sclerosis (MS) requires careful assessment of disease activity, treatment duration, and patient-specific factors, as recommended by the National Multiple Sclerosis Society 1, 2, 3

For patients on first-line therapy showing disease activity, switching to high-efficacy DMT is appropriate, with disease activity defined as one or more clinical relapses occurring ≥3 months after DMT initiation, or MRI activity defined as ≥1 gadolinium-enhancing lesion OR ≥3 new/enlarging T2 lesions, according to the American Academy of Neurology 2, 3
Incomplete recovery from relapses should prompt evaluation for DMT adjustment, as suggested by the Multiple Sclerosis Association of America 4

Ensure adequate treatment duration before declaring failure, with relapses must occur ≥3 months after DMT initiation to be considered breakthrough disease, as recommended by the European Committee for Treatment and Research in Multiple Sclerosis 2, 3
Early activity may represent disease course before therapeutic effect, and pseudoatrophy effect can cause excessive brain volume decrease within 6-12 months due to inflammation resolution, which should not be mistaken for progression, according to the National Institute of Neurological Disorders and Stroke 2, 3, 4, 5

For highly active MS with markers of aggressive disease, escalation to high-efficacy DMT should occur after failure of a single high-efficacy DMT after a meaningful treatment period, as recommended by the International Multiple Sclerosis Management Practice Guidelines 6

Follow-up MRI should be conducted at least once yearly, but patients at risk of serious treatment-related adverse events require monitoring every 3-4 months, with protocol including T2 FLAIR and T2-weighted sequences to detect new/enlarging lesions, and gadolinium-enhanced T1-weighted sequences to identify high inflammatory activity, according to the Radiological Society of North America 7

Carryover effects can complicate mobilization and immune reconstitution, particularly after long-acting lymphodepleting agents like alemtuzumab or after multiple treatment lines, as warned by the Food and Drug Administration 1, 2, 3
Not all MRI activity represents clinically meaningful treatment failure, and the number of baseline relapses predicts post-switch outcomes, according to the National Multiple Sclerosis Society 6

For patients switching from natalizumab to other therapeutics, enhanced pharmacovigilance including brain MRI every 3-4 months for up to 12 months is required to detect resurgent MS activity and opportunistic infections, as recommended by the Centers for Disease Control and Prevention 7

For highly active, treatment-refractory MS after failure of high-efficacy DMT, AHSCT should be considered as appropriate escalation therapy, with optimal candidates including age <45 years, disease duration <10 years, EDSS score <4.0, high focal inflammation, and relapsing-remitting MS subtype, according to the International Multiple Sclerosis Management Practice Guidelines 6, 4