Ritlecitinib in CTCL

INCLUSION CRITERIA: * Age ≥ 18 years at time of enrollment * CTCL \>10% BSA involvement (stage IB-IVA by ISCL/EORTC staging criteria), previously confirmed by histopathology * CTCL subtypes eligible for this study include Mycosis fungoides and its subtypes, as well as Sézary Syndrome. * Failure of at least 2 skin-directed (ISCL/EORTC stage IB-IIA, i.e. early stage disease) or systemic treatments (ISCL/EORTC stage IIB-IVA, i.e. late stage disease) due to progression or toxicity as assessed by the prescribing physician or by the principal investigator, or insufficient response to established skin-directed or systemic treatments. i. Patients with documented CD30-positive CTCL must have previously received or be intolerant to brentuximab vedotin. * Adequate hematological (Hb\>9.0g/dl, absolute neutrophil count \>1200/ul, platelets \>75x10\^9/L, absolute \[non-malignant\] lymphocyte count \>800/ul), hepatic (AST and ALT \<2x times upper limit of normal), and renal function (eGFR \[CKD-EPI creatinine equation \>50mL/min/1.73m2) * ECOG ≤ 2 (Eastern Cooperative Oncology Group scoring system used to quantify general well-being and activities of daily life; scores range from 0 to 5 where 0 represents perfect health and 5 represents death.) * Ability to take oral medication without crushing, dissolving or chewing tablets * Ability to understand and the willingness to sign a written informed consent * In the investigator's opinion, the patient has the ability to communicate satisfact…