Therapeutic Advances and Challenges in the Treatment of Progressive Multiple Sclerosis.

Despite the fact that majority of patients with multiple sclerosis (MS) have relapsing-remitting disease, many transition to secondary progressive disease (SPMS) over time. This transition is thought to be related to neurodegenerative processes increasingly predominating over inflammatory processes as the driving forces of disability. However, some patients initially present with primary progressive disease (PPMS) that is characterized by a gradual accumulation of neurological symptoms and subsequent disability accumulation. The treatment of both PPMS and SPMS, collectively referred to as progressive MS, has proven quite challenging due to the multifactorial and poorly understood pathophysiology of multiple sclerosis in general, specifically that of progressive disease. The purpose of this article is to discuss important clinical and pathophysiologic differences between relapsing and progressive forms of MS, review previous notable trials of drugs in progressive MS, examine current literature regarding recent and promising progressive MS treatments, and discuss future considerations for progressive MS therapeutics and management. Specifically, the current evidence regarding treatment of progressive MS with ocrelizumab, simvastatin, ibudilast, alpha-lipoic acid, high-dose biotin, siponimod, and cell-based therapies are discussed.