The FDA approved Roche's ocrelizumab for the treatment of relapsing and primary progressive multiple sclerosis (PPMS), wrapping up a 40-year development history for the anti-CD20 monoclonal antibody (mAb). This is the first drug approval for PPMS, a form of the neurodegenerative disease that affects around 15% of multiple sclerosis patients and is characterized by steadily worsening neurological function without any early relapses or remissions.
Over decades of research, scientists have laboriously overturned the view that T cells are the only driver of autoimmune damage in multiple sclerosis. They have shown that B cells can contribute to disease pathogenesis through antigen presentation, autoantibody production and cytokine secretion. Clinical studies with the B cell-depleting anti-CD20 mAb rituximab also showed signs of early promise in PPMS. Although the community was dismayed when the development of rituximab for PPMS was suspended in 2010, ocrelizumab is a next-generation fully humanized anti-CD20 mAb that finally fills the gap.
In a phase III study in 732 patients with PPMS, 33% of ocrelizumab-treated patients had disability progression confirmed at 12 weeks, compared with 39% of placebo participants. Neurologists welcomed these results, even if some cautioned that the treatment benefit is modest. Adverse events that were more frequent with ocrelizumab than with placebo included infusion-related reactions, upper respiratory tract infections and oral herpes infections. The treatment may also increase the risk of neoplasms.
Companies are developing other candidates that modulate a range of targets — including Novartis's sphingosine 1-phosphate receptor modulator siponimod and AB Science's tyrosine kinase inhibitor masitinib — for primary and secondary progressive forms of multiple sclerosis (Nature 540, S7–S9; 2016).
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Mullard, A. FDA approves first drug for primary progressive multiple sclerosis. Nat Rev Drug Discov 16, 305 (2017). https://doi.org/10.1038/nrd.2017.88