DRESS Syndrome and Daclizumab Failure-Were Potentially Dangerous Signs Missed in Clinical Trials?

The US Food and Drug Administration (FDA) approved Zinbryta, an interleukin-2 receptor blocking antibody (daclizumab; Biogen and AbbVie) for the treatment of adults with relapsing forms of multiple sclerosis (MS) in May, 2016. It was also approved by the European Union in July, 2016. Zinbryta is a long-acting, self-administered monthly injection that was branded as a new MS drug for patients who needed a "new option for treatment." It blocks interleukin-2 receptor alpha (CD25) and modulates T-cell expansion. The drug was withdrawn from the market in March, 2018 following 12 reports from Germany (9), United States (2), and Spain (1) following the development of "inflammatory encephalitis and meningoencephalitis" in patients on Zinbryta. Although cases of hepatotoxicity made news with Zinbryta earlier along this drug's postmarketing journey in the treatment of patients with MS, the European Medicines Agency (EMA) ordered a review of the risks of hepatotoxicity with Zinbryta use June, 2017; this analysis will focus on the pharmacovigilance data concerning the central nervous system (CNS) complications. The details of the CNS complications have been elucidated by EMA. Every drug failure provides an opportunity for learning, but it is also noteworthy that no FDA-approved MS drug in modern times has met with such an untimely, sudden, and inglorious exit. This should serve as a cautionary tale for all clinicians who use "newer MS drugs" that have mushroomed in recent memory following a flurry of recent FDA approvals.