Lawrence Steinman, MD, Stanford University, Stanford, CA, outlines important areas for future research in multiple sclerosis (MS). The MS treatment armamentarium has grown rapidly in recent years, with many more effective therapies available to prevent relapses. However, targeting progressive disease biology and repairing established damage has proved more difficult. While ocrelizumab has been a breakthrough for primary progressive disease in recent years, more treatment options are needed. Central nervous system (CNS) penetration is another challenge in the development of efficacious agents for progressive disease, where CNS resident immune cells are thought to play an important role. This interview took place during the European Academy of Neurology 2021 congress.