This is a prospective, single-arm, open-label phase II study of Chidamide in combination with R-CHOP in the treatment of de novo, elderly, high-risk diffuse large B cell lymphoma patients.

Inclusion Criteria:

• Pathologically confirmed diffuse large B-cell lymphoma, CD20 positive
• Age 61-75 years
• ECOG 0,1,2
• Life expectancy>6 months
• Informed consented
• IPI>1

Exclusion Criteria:

• Chemotherapy before
• Stem cell transplantation before
• History of malignancy except for basal cell or squamous cell carcinoma of the skin or carcinoma in situ of the cervix
• Uncontrollable cardio-cerebral vascular, coagulative, autoimmune, serious infectious disease
• Primary CNS lymphoma
• LVEF≤50%
• Lab at enrollment (Unless caused by lymphoma) Neutrophile<1.5*10^9/L Platelet<75*10^9/L ALT or AST >2*ULN,AKP or bilirubin >1.5*ULN Creatinine>1.5*ULN
• Other uncontrollable medical condition that may that may interfere the participation of the study
• Not able to comply to the protocol for mental or other unknown reasons
• Pregnant or lactation
• HIV infection
• If HbsAg positive, should check HBV DNA, DNA positive patients cannot be enrolled. If HBsAg negative but HBcAb positive (whatever HBsAb status), should check HBV DNA,DNA positive patients cannot be enrolled.