Sintilimab, Pegaspargase and Anlotinib for Stage IV Natural Killer /T-cell Lymphoma

Inclusion Criteria: * Histopathology and immunohistochemistry confirmed diagnosis of NK/T-cell lymphoma according to WHO 2016 criteria. * Stage IV disease according Lugano 2014 staging system. Newly diagnosed patients, or relapsed disease without a history of asparaginase-containing regimen. * PET/CT or CT/MRI with at least one objectively evaluable lesion. * The age is greater than 65 years old. Those who are younger than 65 years should have a documented history unfit for high-dose combination chemotherapy (ie. high doses of methotrexate or high doses of dexamethasone, or autologous hematopoietic stem cell transplantation). * General status ECOG score 0-3 points. * The laboratory test within 1 week before enrollment meets the following conditions: Blood routine: Hb\>80g/L, PLT\>50×109/L. Liver function: ALT, AST, TBIL ≤ 2 times the upper limit of normal. Renal function: Cr is normal. Coagulation : plasma fibrinogen ≥ 1.0g / L. Cardiac function: LVEF≥50%, ECG does not suggest any acute myocardial infarction, arrhythmia or atrioventricular conduction above I Blocking. * Sign the informed consent form. * Voluntary compliance with research protocols, follow-up plans, laboratory and auxiliary examinations. Exclusion Criteria: * Patients with a history of pancreatitis. * Active infection requires ICU treatment. * Concomitant HCV or HIV infection. Patients who are infected with HBV at the same time are not excluded. * Serious complications such as fulminant DIC. * Significant…