Overview

This study is being done to assess mogamulizumab-associated rash in patients diagnosed with mycosis fungoides or sezary syndrome and treated with standard of care mogamulizumab. One of the most common side effects of mogamulizumab is a rash, currently named mogamulizumab-associated rash (MAR) which can look like MF or SS. However, mogamulizumab-associated rash (MAR) does not indicate failure of mogamulizumab, and may be a sign that the drug is working. If not properly evaluated, mogamulizumab-associated rash (MAR) could be misinterpreted as worsening of mycosis fungoides/sezary syndrome, which could lead doctors to recommend stopping mogamulizumab treatment early. The information learned by doing this research study may help tell the difference between mogamulizumab-associated rash (MAR) (sometimes also called "drug eruption") and worsening of the disease. It may also help to uncover information about the cause of mogamulizumab-associated rash (MAR).

Eligibility

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)

Exclusion Criteria:

• * Other concomitant systemic and skin directed Cutaneous T-cell Lymphoma (CTCL) regimens except for topical steroids
  • Prior treatment with mogamulizumab