Ocrevus (generic name, ocrelizumab) is a humanized monoclonal antibody that was approved by the U.S. Food and Drug Administration on March 28, 2017. Ocrevus was developed by Genentech, a member of the Roche Group, as a treatment for people with multiple sclerosis (MS).
The treatment targets B-lymphocytes, a type of immune cell, that express a protein called CD20 on their surface, giving the drug an immunosuppressive function. It is designed to reduce the rates of immune system attacks on myelinated neurons, the main trigger of the disease.
Ocrevus is the first FDA-approved therapy that treats both relapsing multiple sclerosis and, in a true breakthrough, primary progressive multiple sclerosis (PPMS), a disease form that previously had no approved treatments.
How Ocrevus works
Ocrevus, an anti-CD20 monoclonal antibody, targets mature B-cells. Almost 95% of B-cells express the CD20 protein on their surface once they mature and do not shed them, which is what makes CD20 a potent marker for therapeutic purposes. It is believed these CD20-positive B-cells target axons and the myelin sheaths of healthy neurons, initiating a cascading series of immune reactions that lead to MS and disability in patients. Studies have shown that ocrelizumab binds to specific B-cells with CD20 markers, but not to stem cells and plasma cells, preserving vital immune functions within the host.
Ocrevus and clinical trials for MS
Genentech had announced in February 2016 favorable results from a pivotal Phase 3 trial called ORATORIO, a randomized, double-blind, global and multi center study evaluating the efficacy and safety of ocrelizumab in 732 patients with PPMS. The drug was injected into the bloodstream as two infusions of 300 mg given two weeks apart every six months. At the end of the study period, it was seen that ocrelizumab had met the study’s primary outcome, significantly reducing clinical disease progression in PPMS patients sustained for at least 12 weeks by 24%(compared to placebo), as measured by the Expanded Disability Status Scale (EDSS).
That same month, the U.S. Food and Drug Administration (FDA) designated ocrelizumab a Breakthrough Therapy as a possible PPMS treatment, a decision meant to expedite its development and review.
Data from two related Phase 3 studies, OPERA I and II, testing the efficacy of the drug in 1,656 patients with relapsing forms of MS, found that ocrelizumab was superior to interferon beta-1a, a well-established MS therapy, reducing the annualized relapse rate (the primary endpoint of both studies) by nearly 50% over a two-year controlled treatment period. Ocrelizumab was into the bloodstream at 600 mg every six months; interferon beta-1a was given by injection under the skin at 44 mcg three times per week.
According to Genentech, Ocrevus was the first investigational medicine to show such positive results in patients with both primary progressive and relapsing forms of MS. The company submitted data from all three studies to regulatory authorities in mid-2016, which paved the way for marketing and commercialization of Ocrevus to treat RMS and PPMS. On June 28, 2016, Genentech announced that the company’s Biologics License Application for Ocrevus had been accepted for FDA review, and that the therapy was granted Priority Review, accelerating the review process. All those efforts resulted in the FDA’s decision to approved Ocrevus on March 28, 2017.
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