Zinbryta (Daclizumab) for MS Treatment

This drug was pulled off the market for safety concerns

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In May 2016, the U.S. Food and Drug Administration (FDA) approved the disease-modifying therapy Zinbryta (daclizumab) for treating relapsing-remitting MS. However, in March of 2018, the manufacturers Biogen and Abbvie announced they were voluntarily withdrawing it from the market worldwide because of growing safety concerns.

Zinbryta was an injected medication that was given underneath the skin (subcutaneously) every four weeks. It's believed to have worked by blocking the binding site on interleukin-2 (IL-2)—a molecule in the immune system that activates your T-cells (what attack the myelin sheaths in your brain and spinal cord).

Zinbryta may also have worked by increasing cells in the immune system called natural killer cells, which kill activated T-cells.

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The Science Behind Zinbryta

Two reviews of literature on Zinbryta were published in 2017, one in the journal Drugs and one in Expert Review of Clinical Pharmacology.

The Drugs paper cited evidence that Zinbryta, injected once a month, was superior to weekly injections of interferon. It also said evidence showed the drug remained effective for at least three years.

The Expert Review paper said it was a convenient and effective treatment for people who haven't had success with other MS drugs. While pointing out that doctors need to be selective about who they prescribe it for and monitor them for severe side effects, it suggested Zinbryta as a possible first-line treatment for people with highly active MS.

In a large study in the The New England Journal of Medicine, 1,841 participants with relapsing-remitting MS were randomly assigned to receive either a dose of Zinbryta 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 magnetic resonance imaging (MRI) was 54 percent less in those who received daclizumab, compared to those who were treated with Avonex.

In another study, published in Lancet, nearly 600 participants with relapsing-remitting MS were randomized to receive a lower dose of Zinbryta (150 milligrams, mg), a higher dose of Zinbryta (300 mg), or a placebo injection. As this was a double-blind study, neither the participants nor the researchers knew which injection was given (this protects the results from being biased). The participants received the injections every four weeks for about a year.

Results suggested that when compared to the placebo, the lower dose of Zinbryta (150 mg) reduced the MS relapse rate by 54 percent, and the higher dose (300 mg) reduced the MS relapse rate by 50 percent. Given the similar results, the lower dose is used to minimize side effects.

Inflammatory Brain Disorders Reported

The withdrawal of Zinbryta began after the European Medicines Agency announced a recall due to 12 worldwide reports of serious inflammatory brain disorders in people taking the drug. The potential danger of the drug simply outweighed the positive study results on its efficacy.

Potential Side Effects of Zinbryta

Like all medications, Zinbryta came with the potential for side effects. Common ones included:

  • Cold symptoms
  • Upper respiratory tract infection or bronchitis
  • Eczema, rash, or another skin reaction
  • Flu
  • Throat pain

Some others were potentially life-threatening. When it was available, the following were listed as black-box warnings:

  • Severe liver injury that may be fatal
  • Colon inflammation
  • Skin reactions
  • Lymph nodes becoming enlarged

The inflammatory brain disorder that resulted in the drug's withdrawal was unknown when Zinbryta was approved for use.

Other drug warnings included:

  • Potential for a serious allergic reaction
  • Increased risk of developing infections
  • Increased risk of depression, including suicidal thinking

Due to the potential for these adverse effects, Zinbryta was most commonly prescribed for people who had not responded to two or more other MS therapies.

Risk Evaluation Program

Because of its highly dangerous side effects, this drug was only prescribed under an FDA drug safety program called the Risk Evaluation and Mitigation Strategy (REMS).

This means that a neurologist had to be specially certified in order to prescribe Zinbryta. The purpose of the program is to make sure people on dangerous drugs are properly monitored, such as with periodic liver function blood tests.

A Word From Verywell

When a new drug comes on the market for MS, it's exciting. For it to be discontinued after less than two years may seem disheartening. The full side-effect profile of a drug isn't generally established right away, though, so unexpected things can happen, and risks may be higher than originally thought.

The medical community is constantly weighing the benefits of a treatment against the risks, and sometimes, the risk is just too high. In the case of Zinbryta, the drug failed that critical test once it was out in the real world.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

By Colleen Doherty, MD
 Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis.