Drug rash with eosinophilia and systemic symptoms due to telaprevir.

We report a case of drug rash with eosinophilia and systemic symptoms (DRESS) due to telaprevir (VX-950), a specific inhibitor of the hepatitis C virus (HCV) serine protease. A 57-year-old woman with chronic hepatitis C was included in a phase 2 rollover study of VX-950. She received VX-950 in combination with pegylated interferon alfa-2a and ribavirin. Six weeks later, she developed a generalized pruritic maculopapular exanthema with malaise, fever, dyspnoea and lymph node swelling. She had an eosinophilia (up to 2.7 × 109 cells/l), large activated lymphocytes and increased concentrations of aminotransferases. Histological examination of a cutaneous biopsy was consistent with a drug rash reaction. The HCV treatment was stopped, and she was treated with topical and oral steroids. Cutaneous and systemic symptoms disappeared within 1 month. Telaprevir was considered the culprit drug. We report to our knowledge the first case of DRESS syndrome due to telaprevir. The safety data of telaprevir is derived mainly from the PROVE1, PROVE2 and PROVE3 studies. They showed a high frequency of cutaneous side effects reported under the imprecise terms of pruritus and rash, leading to an increased rate of treatment discontinuation. Telaprevir, due to its efficacy, is probably on the way to obtaining regulatory approval in the near future. It is therefore important to be aware of the high incidence of cutaneous side effects and better describe them. Our observation suggests that potentially severe hypersensitivity reactions may belong to the spectrum of rashes induced by this drug.