A Single-center, Single-arm, Open-label Phase IIA Clinical Trial to Investigate Efficacy and Safety of Ritlecitinib (PF-06651600) in Patients With Cutaneous T Cell Lymphomas

After providing informed consent, patients will be assessed for study eligibility at the Screening visit (day -28 to day -1) which includes: assessment of inclusion/exclusion criteria; targeted physical examination (including vital signs); mSWAT scoring and disease staging; electrocardiogram (ECG); review of medical history and concomitant medications as well as prior medications/treatments; and serum pregnancy test (if applicable). Laboratory tests will be performed for Complete Blood Count (CBC) with differentials (basophils, eosinophils, lymphocytes, monocytes, neutrophils), serum chemistry including albumin, alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), creatinine, creatine kinase, potassium, sodium, total bilirubin, LDH, viral surveillance panel (EBV, CMV, HSV1, HSV2, and VZV), as well as hepatitis B surface antigen (HBsAg), HBcAb, hepatitis C antibody, and undergo testing for human immunodeficiency virus (HIV). Urinalysis will be performed. Patients will also undergo tuberculin purified protein derivative (PPD) or QuantiFERON TB-Gold test (QFT) testing. Patients will also undergo flow cytometric analyses and TCR rearrangement studies of peripheral blood to monitor potential CTCL blood involvement. CT scans with PET (positron emission tomography) scans will be performed within 4 weeks before baseline to help establish or confirm peripheral lymph node size and assign TNM classification, or at any time if internal involvement is suspected by the investigator.

Patients who meet eligibility criteria (meeting all inclusion and no exclusion criteria) will undergo Baseline / Day 0 assessments. These assessments include vital signs and targeted physical examination, mSWAT scoring, clinical disease staging, questionnaires, clinical photography, urine pregnancy test (if applicable), and blood collection for chemistry, hematology, mechanistic studies, baseline for drug levels, blood DNA analysis, blood RNA analysis, and blood proteomic analysis. Two skin biopsies will be obtained (one from an involved area and one from an adjacent uninvolved area). Concomitant medications and any adverse events will be assessed.

Patients will then receive the first oral dose (200mg) of ritlecitinib. Patients will continue to receive the study drug QD through Week 24.

Patients will return for visits every 2-4 weeks to have the following performed: vital signs and targeted physical will be taken; concomitant medications and any adverse events will be assessed.

Safety, laboratory, and clinical assessments, as well as questionnaires will be performed at specified clinic visits. A serum pregnancy test will be performed at Screening and urine pregnancy tests will be performed at Baseline and every 2-4 weeks prior to administration of the study drug, if applicable. Clinical photographs of the skin lesions will be taken at each visit.