Emerging drugs for primary progressive multiple sclerosis.

The identification of effective therapies for progressive forms of multiple sclerosis (MS) has remains a priority and challenge for the global MS community. Despite a few proposed mechanisms, a more complete understanding of the mechanisms involved in the pathogenesis of these MS phenotypes, animal models that incorporate these pathogenic characteristics, novel trial designs, drug repurposing strategies, and new models of collaboration between clinical and basic science personnel may be required in identifying effective therapies. Areas covered: Here, we review the current knowledge on putative pathogenic mechanisms in primary progressive MS (PPMS). Also, the rationale and outcomes of key phase II or III trial initiatives in PPMS are summarized. Future perspectives are outlined. Expert opinion: The recent approval of ocrelizumab is a major milestone forward in the therapy of PPMS. One reason for success of this drug is appropriate patient selection. The ultimate goal in PPMS therapy should be the reversal of disability, and the arrest of disease progression. Our current understanding of PPMS suggests that a combination of immune-modulatory, myelin-restorative, and neuro-regenerative therapies particularly early in the disease course would be a reasonable strategy. Finally, selection of appropriate patients, selection of appropriate outcomes and monitoring therapy is again crucial for success of therapeutic strategies.