A Study of Bexarotene Combined With Radiotherapy in People With Mycosis Fungoides

Inclusion Criteria: * Age ≥18 years * Pathologically confirmed cutaneous T-cell lymphoma consistent with mycosis fungoides (MF) based on biopsy done or reviewed at MSKCC * Stage IB or higher MF per ISCL/EORTC criteria; concurrent diagnosis of Sézary syndrome permissible. Patients who have not had prior systemic therapies and refractory/relapsed patients are eligible. * Baseline mSWAT score of at least 10 * Stable topical steroids or systemic antipruritic agent (e.g. antihistamines, doxepin, GABA analogs) preceding study entry is permissible, but no new prescribed or over the counter topical or systemic anti-pruritics started post-enrollment * Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 * Ability to provide informed consent Exclusion Criteria: * Any oral retinoid therapy for any indication within 3 weeks of the first dose of study drug * Prior TSEB (prior focal skin-directed RT acceptable) * Concurrent diagnosis of systemic anaplastic large cell lymphoma (ALCL) or another non-Hodgkin lymphoma * Concurrent diagnosis of additional non-skin malignancy * Pregnancy * Patients unwilling to use two forms of barrier contraception while taking study medication * Receipt of treatment with another investigational device or drug (at present or within 2 weeks of enrollment) * Familial hypertriglyceridemia or other medical conditions in which use of bexarotene would be contraindicated * High likelihood of protocol non-compliance (in opinion of investigator) * Systemic steroids within two weeks of first dose of study drug (patients on systemic steroids for non-disease related conditions will be permitted per investigator discretion) Prohibited concurrent medications * Gemfibrozil is contraindicated as may increase bexarotene concentrations * Bexarotene is a minor CYP3A4 substrate: avoid strong/moderate CYP3A4 inducers and inhibitors, if possible, but concomitant use is not a contraindication Bexarotene is a moderate CYP3A4 inducer: avoid concurrent administration with CYP3A4 sensitive substrates, for which minimal concentration changes may lead to therapeutic failures of the substrate (e.g. cyclosporine, tacrolimus, sirolimus, quinidine, fentanyl), if possible