The window of opportunity for treatment of progressive multiple sclerosis

Purpose of review Based on the knowledge of disease mechanisms in the progressive course of multiple sclerosis and the experience from randomized clinical trials, we assessed the timing of disease-modifying therapy in patients with progressive multiple sclerosis to define the optimal window of opportunity for treatment of progressive multiple sclerosis. Recent findings In progressive multiple sclerosis both small molecules that cross the blood--brain barrier (siponimod) and monoclonal antibodies (ocrelizumab) have shown therapeutic efficacy and have been approved for treatment of progressive multiple sclerosis. However, the majority of phase II and phase III trials in progressive forms of multiple sclerosis have been negative, probably owing to either late start of treatment or use of drugs that are ineffective for treatment of progressive multiple sclerosis. Results from phase II and III trials suggest that the window of opportunity for treatment of progressive multiple sclerosis with anti-inflammatory drugs is predominantly in the early phase of the progressive disease course when patients have lower age, shorter duration of progressive multiple sclerosis, and more pronounced clinical and MRI inflammatory activity. Ongoing trials of neuroprotective drugs may widen the window of opportunity by expanding targeted pathophysiologies.