Phototherapy and Mogamulizumab in Early Stage MF (PLIGHT)

Inclusion Criteria: * Be willing and able to provide written informed consent/assent for the trial. * Be at least 18 years of age on day of signing informed consent. * Able to adhere to the study visit schedule and other protocol requirements. * Diagnosis of mycosis fungoides (MF) based on a combination of histological, clinical, and immunophenotypical criteria. The histological criteria will be based on skin biopsy from the most representative skin area. * CTCL (Mycosis fungoides) stage IA-IIA (early stage) at the time of screening with either B0 blood involvement with a positive T-cell receptor (TCR) gene rearrangement or B1 blood involvement with positive TCR gene rearrangement. The TNMB system will be used to classify the stage of disease. * Any number of prior therapies is allowed. * Patients must have stable disease (SD), partial response (PR) or disease progression (PD) after 3 or more months prior to date of consent of one of the following treatments: Phototherapy \[narrow-band ultraviolet B (nb-UVB) or Psoralen ultraviolet A (PUVA)\] alone or PUVA in combination with topical therapy such as nitrogen mustard, steroids, or bexarotene gel progression of skin disease on long-term maintenance phototherapy. * A minimum washout period of 14 days prior after previous CTCL therapy before the first day of treatment. * Eastern Cooperative Oncology Group (ECOG) performance status 0-1. * Subjects on a stable dose of a low dose systemic corticosteroid (≤ 20 mg prednisone equivale…