New MS therapy approved in Canada: Zinbryta
A new MS treatment was approved in Canada in December for the treatment of the relapsing-remitting form of multiple sclerosis (RRMS). Zinbryta (daclizumab) can be used in people who don’t have a good enough response or can’t tolerate at least one prior MS medication. The medication has also been approved for use in the U.S. and Europe.
Zinbryta is administered by an injection under the skin (subcutaneous) once a month. The drug will be provided in a pre-filled syringe, like other injectable MS medications. Zinbryta is a monoclonal antibody (i.e. a “biological”, like Tysabri and Lemtrada), which targets a specific protein in the body (called CD25) which acts as a receptor for signalling molecules (called IL-2) found on activated immune cells. These effects serve to reduce the immune system’s inflammatory response. (The drug is also used to prevent tissue rejection in organ transplant patients.) In addition, Zinbryta acts on components of the innate immune system, called natural killer (NK) cells (Pfender & Martin. Exp Neurol 2014;262 Pt A:44-51).
Zinbryta was approved based on the results of two key trials. In the phase IIb study called SELECT, treatment significantly lowered the number of relapses compared to a placebo over a one-year period (Gold and colleagues. Lancet 2013;381:2167-2175). There was one death in a person treated with Zinbryta due to a rare type of infection of the lower back. A second person died of autoimmune hepatitis during the one-year extension (called SELECTION) of the study (Giovannoni and colleagues. Lancet Neurol 2014;13:472-481).
In the phase III trial (called DECIDE), people received either Zinbryta once-monthly or Avonex once-weekly for up to three years (Kappos and colleagues. N Engl J Med 2015;373:1418-1428). Zinbryta had a greater effect on relapses and inflammatory lesions on the MRI compared to Avonex, although there was no difference between the two treatments with respect to short-term worsening of disability.
The side effects associated with Zinbryta included skin reactions (such as psoriasis, eczema or dermatitis), which were serious in about 2% of people; infections (such as influenza or bronchitis); and effects on the liver. About 5% of people had depression during treatment with Zinbryta (compared to 1% with Avonex).
One of the more common problems is skin reactions, which occur in about one-third of people taking Zinbryta (Kircik and colleagues. ECTRIMS 2016; abstract P550). These are generally mild; 14% had moderate reactions, which persisted for an average of 40 days; and 2% had severe reactions, which lasted for an average of 71 days.
Most people taking Zinbryta will respond to a flu shot (Mehta and colleagues. ECTRIMS 2016; abstract P526), but should not receive live vaccines (e.g. against measles, polio, rotavirus, etc.).
The drug monograph includes a warning about a risk of severe liver injury, so blood tests are needed before starting treatment, and before each of the monthly doses. Treatment may also be associated with a higher risk of other immune conditions, such as skin reactions or colitis. People are advised to talk to their doctor if they develop a widespread rash. Suspected side effects should be reported to your doctor and/or (in Canada) to Health Canada’s MedEffect online database (http://hc-sc.gc.ca/dhp-mps/medeff/index-eng.php).
Distribution of Zinbryta will be through the Biogen ONE Support Program, available in Canada toll-free at 1-855-676-6300.
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