Pembrolizumab and Radiotherapy for Patients With NK/T Cell Lymphoma

Inclusion Criteria: * Confirmed histological diagnosis of NK/T Cell Lymphoma * No previous anti-lymphoma treatment * Age ≥ 18 years * Ann Arbor stage I-II * At least one measurable/evaluable site after diagnostic biopsy before treatment start * At least one of the following high-risk features: age \> 60 years, elevated LDH, stage II, primary tumor invasion * Patient ineligible to receive full dose standard chemotherapy * ECOG performance status of 0-1 * Signed Informed consent * Ability to comply with the protocol * Adequate hematological and organ function; * Tumor tissue (fresh preferred, archival tissue is also acceptable) * For women of childbearing potential a negative pregnancy test on day 1 of cycle 1 and agree to adopt an adequate measure to avoid pregnancy during study treatment and for at least one year from end of treatment * For men agreement to remain abstinent or to use barrier contraception Exclusion Criteria: * Advanced stage disease (AA stage III-IV) * Extranasal type NKTCL * History of autoimmune disease * History of other(s) infiltrating cancer(s) in the previous 3 years that were not treated with curative intent or who are still receiving anticancer therapy (including hormone therapy for breast or prostate cancer). * History of (non-infectious) pneumonitis that required steroids; evidence of interstitial lung disease or active, non-infectious pneumonitis * Active infection requiring systemic therapy * Significant cardiovascular disease, myocardial infar…