This is an interventional, phase II, open label, single arm, multicentric clinical trial to be conducted in China.~The primary objective is to test the efficacy of concurrent RT-Pembrolizumab in patients with limited stage NK/T cell lymphoma and who are not eligible to receive chemotherapy.~The secondary objectives are to further explore the efficacy and safety of a the combination of RT and Pembrolizumab as initial treatment of the patients population.~All eligible patients will be treated with standard IFRT and concurrent pembrolizumab administered intravenously, over 30 minutes starting on day 1 of RT (C1D1, at the dose of 200 mg, every 3 weeks). After 6 cycles of pembrolizumab patients will undergo restaging imaging. Patients with complete remission (CR), partial response (PR) and stable disease (SD) will continue with pembrolizumab maintenance up to 2 years that will be administered intravenously, at the dose of 200 mg, over 30 minutes on day 1 every 3 weeks up to 34 cycles.~The follow-up period will last up to 4 years from treatment start.
Aim of the trial is to evaluate the activity and tolerability of the anti PD1 agent Pembrolizumab in combination with RadioTherapy for the initial treatment of previously untreated patients with limited stage NK/T cell lymphoma who are not eligible to chemotherapy.~It is planned to enroll 30 patients in chinese sites.~All eligible patients will be treated with standard radiotherapy and concurrent pembrolizumab administered intravenously every 3 weeks. After 6 cycles of pembrolizumab patients with complete remission, partial response and stable disease will continue with pembrolizumab maintenance up to 2 years.~Patients will be followed up to 4 years from treatment start.