What is Zinbryta (Daclizumab)?

How Effective Is Zinbryta and What Are Its Potential Side Effects?

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In May 2016, the United States Food and Drug Administration approved the disease-modifying therapy Zinbryta (daclizumab) for treating relapsing-remitting MS.

Zinbryta is a medication given underneath the skin every 4 weeks. It is believed to work by blocking the binding site on interleukin-2 (IL-2)—a molecule in the immune system that activates your T-cells. By blocking the receptor on interleukin-2, T cells are not activated to attack the myelin sheath in your brain and spinal cord.

Zinbyta may also work by increasing cells in the immune system called natural killer cells, which kill activated T cells that are programmed to attack the myelin sheath.

The Science Behind Zinbryta

In a large study in the The New England Journal of Medicine, 1841 participants with relapsing-remitting MS were randomly assigned to receive either a dose of Zinbryta (daclizumab) every four weeks or Avonex (interferon β-1a) weekly for nearly three years.

Results revealed that the participants who received Zinbryta had 45 percent fewer MS relapses yearly than those who received Avonex.

In addition, the number of new or enlarging MS lesions on MRI was 54 percent less in those who received daclizumab, compared to those who were treated with Avonex.

In another study in Lancet, nearly 600 participants with relapsing-remitting MS were randomized to receive a lower dose of Zinbryta (150mg), a higher dose of Zinbryta (300mg), or a placebo injection. The participants nor the researchers knew which injection was given—this is called a double-blind study and protects the results from being biased. The participants received the injections weekly for about a year.

Results suggested that when compared to the placebo, the lower dose of Zinbryta (150mg) reduced the MS relapse rate by 54 percent, and the higher dose (300mg) reduced the MS relapse rate by 50 percent. So, the lower versus higher dose gave pretty similar results, which is why the lower dose is used to minimize adverse effects.

Potential Adverse Effects of Zinbryta

Like all medications, Zinbryta carries the potential for adverse side effects, some even possibly life-threatening. These are listed as a boxed warning and include:

  • severe liver injury that may be fatal
  • colon inflammation
  • skin reactions
  • lymph nodes becoming enlarged

Other drug warnings include the potential for a serious allergic reaction, and an increased risk of developing infections and depression, including suicidal thinking.

In terms of common adverse effects, those reported in the study comparing Zinbryta to Avonex include:

  • cold symptoms
  • upper respiratory tract infection or bronchitis
  • eczema, rash, or another skin reaction
  • flu
  • throat pain
  • enlarged lymph nodes

Other commonly reported adverse effects include a rise in a liver enzyme and depression.

Due to the potential for these adverse effects, Zinbryta is only recommended for people with MS who have not responded to two or more other MS therapies.

In addition, it can only be prescribed under the program called the Risk Evaluation and Mitigation Strategy (REMS). This means that your neurologist has to be certified to treat you with Zinbryta. The purpose of the program is to make sure that your neurologist is monitoring you for possible adverse effects, like checking periodic liver function blood tests.

A Word From Verywell

It's invigorating when a new MS disease-modifying therapy is approved by the FDA, and the good news is that there are more in the pipeline. That being said, this medication may or may not be the right one for you.

There is a lot to consider when choosing an MS therapy like your other medical conditions, whether you may become pregnant in the near future, and potential discomforts and adverse effects associated with it.

Also, Zinbryta may not be "better" than your current MS disease-modifying therapy. There was only one study comparing it to Avonex. So while Zinbryta reduced the number of relapses compared to Avonex, we cannot generalize this to other MS therapies.

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