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

Inclusion Criteria

• •\* Adult patients (\>= 18 years of age) diagnosed with relapsed/refractory Mycosis Fungoides (MF) stage IB, IIA, IIB, III and IV or Sezary Syndrome(SS), and selected by their treating physician to receive single agent mogamulizumab (newly initiated)
• •* Signed informed consent
• •* Willing to undergo baseline biopsy and during treatment to evaluate for Mogamulizumab-Associated Rash (MAR) if clinically indicated
• •* Willing to provide blood sample at baseline, and if applicable, at onset of Mogamulizumab-Associated Rash (MAR)