Pembrolizumab in combination with gemcitabine for previously treated mycosis fungoides and Sezary syndrome: efficacy and characterization of immune response

Primary objective: Determine preliminary clinical effectiveness of pembrolizumab plus gemcitabine in previously treated MF and SS with overall response rate (ORR) using the composite global response criteria including: radiological imaging (PET/CT scans), flow cytometry and mSWAT assessments. 2. Secondary objectives: a. To estimate duration of response (DOR) of pembrolizumab plus gemcitabine in previously treated MF and SS. b. To estimate progression-free survival (PFS) pembrolizumab plus gemcitabine in previously treated MF and SS. c. To estimate overall survival (OS) of patients with pembrolizumab plus gemcitabine in previously treated MF and SS. d. To evaluate safety and tolerability of treatment with pembrolizumab plus gemcitabine in MF/SS.

Are you Eligible? (Inclusion Criteria)

• a) Confirmed mycosis fungoides/Sezary syndrome, disease stage IB (defined as patches, plaque, or papules that involve 10% of the skin surface viscera) or higher. b) Age ≥ 18 years. c) ECOG Performance Score between 0-1 d) Receipt of at least one prior systemic therapy for MF/SS. e) Previous systemic anti-cancer therapy must have been discontinued at least 2 weeks prior to treatment. f) Topical or systemic steroids (equivalent to ≤ 10 mg/day of prednisone) may be considered if dose has been constant and discontinuation may lead to rebound flare in disease, adrenal insufficiency, and/or unnecessary suffering. g) Prior therapy with gemcitabine allowed. h) Laboratory inclusion criteria. i) The participant (or legally acceptable representative if applicable) provides written informed consent for the trial. j) A female participant is eligible to participate if she is not pregnant, not breastfeeding k) A male participant must agree to use a contraception of this protocol from screening and through 6 months after the last dose of gemcitabine or 120 days after the last dose of pembrolizumab (whichever is later) and refrain from donating sperm during this period.