Ocrevus approved in Canada for relapsing-remitting MS
A new type of therapy to treat relapsing-remitting multiple sclerosis has now been approved in Canada. Ocrevus will be used to treat adults with active MS. While this is likely to mean people who haven’t responded well enough to a prior medication, it could also be used as a first-choice drug in people with aggressive MS from the outset. At the moment, Ocrevus is not approved for use in people with primary-progressive MS, unlike the situation in the U.S. (see FDA approves first treatment for primary-progressive MS, MSology, March 31, 2017).
Ocrevus is a monoclonal antibody that primarily targets B cells, a type of immune cell that produces antibodies. B cells also interact with other immune cells (called T cells) to cause an immune reaction. Other MS therapies typically target both T and B cells (e.g. Gilenya, Aubagio, Lemtrada).
Like other monoclonal antibodies (such as Tysabri and Lemtrada), Ocrevus is taken as a slow drip into a vein (an infusion). Treatment is administered every 6 months (2 infusions two weeks apart when you start, one infusion every 6 months thereafter). The infusion takes 3-4 hours, followed by an hour of observation time. The most common side effect is reactions to the infusion (such as itchiness, rash, throat tightening, chest pain, and low blood pressure), so a course of steroids and other medications (such as antihistamines) are advised prior to the infusion.
Two clinical studies (called OPERA I and II) compared Ocrevus to Rebif rather than a placebo (Hauser and colleagues. N Engl J Med 2017;376:221-234). They found that Ocrevus was significantly more effective than Rebif in lowering the risk of relapses, reducing inflammatory lesions in the brain, and in slowing short-term disability.
Ocrevus is generally well-tolerated. Since it reduces the function of the immune system, side effects can include infections (such as respiratory tract infections). There is also an increased risk of herpes infections (e.g. shingles, cold sores, genital sores), which occurred in 6% of people taking Ocrevus. These are generally not new infections, but rather a reactivation of the virus. In the same vein, people need to be screened for hepatitis before taking Ocrevus since there is a risk that pre-existing hepatitis will be reactivated.
The Canadian product label also includes a precaution about depression (not included in the FDA label). Ocrevus should be used with caution in people with a history of depression, or current symptoms of depression. In the two clinical studies, 8.5% of people reported depression (compared to 7.9% taking Rebif).
In addition, there may be a risk of cancers with Ocrevus, including breast cancer. The overall estimated risk of cancer is 0.44% per year (Kappos and colleagues. AAN 2017; abstract P5.407), which translates to 1 case per year for every 227 people treated. (It should be noted that the cancer risk in the general population isn’t zero.)
Women starting on Ocrevus will need to take effective contraception for at least 6 months after the last dose. They should also avoid breast-feeding if they’re on the drug.
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