A Prospective, US-based Study Assessing Mogamulizumab-associated Rash in Patients Diagnosed With Mycosis Fungoides or Sezary Syndrome and Treated With Standard of Care Mogamulizumab

PRIMARY OBJECTIVE: I. To assess the incidence of mogamulizumab-associated rash (MAR) and its association with overall response in patients with cutaneous T-cell lymphoma (CTCL); mycosis fungoides \[MF\] and sezary syndrome \[SS\] subtypes) treated with mogamulizumab. OUTLINE: This is an observational study. Patients complete questionnaires, have photographs of their skin taken, and undergo blood sample collection and skin biopsies on study. Patients' medical records are also reviewed.