The prognosis of PTCL (except early stage ALK+ ALCL) is dismal. Previous study showed that single agent lenalidomide showed promising therapeutic activity in patients with relapsed or refractory PTCL. The investigators therefore design this phase II study to investigate the safety and efficacy of lenalidomide in combination with CHOP in patients with treatment-naive PTCL.

Inclusion Criteria:

1. Histologically confirmed PTCL, NOS, AITL, ALK- ALCL, phase III-IV ALK+ ALCL, EATL according to WHO 2016 criteria.
2. ECOG PS 0-2
3. Age 18-70 years old
4. Expected survival ≥ 12 weeks
5. A measurable or evaluable disease at the time of enrolment (diameter ≥1.5cm)
6. Understand and voluntarily sign an informed consent form, able to adhere to the study visit schedule and other protocol requirements.
7. Female subjects in childbearing age, their serum or urine pregnancy test must be negative. All patients must agree to take effective contraceptive measures during the trial measures

Exclusion Criteria:

1. Women who are pregnant or lactating. Patients have breeding intent in 12 months or cannot take effective contraceptive measures during the trial measures
2. Active hepatitis B or hepatitis C virus infection, as well as acquired, congenital immune deficiency diseases, including but not limited to HIV infected persons
3. Patients known to have varicella or herpes zoster virus infection
4. Previous exposure to any anti-tumor therapy
5. Poor hepatic and/or renal function, defined as total bilirubin, ALT, AST, Cr more than two fold of upper normal level,Ccr# 50 mL/min unless these abnormalities were related to the lymphoma
6. History of DVT or PE within past 12 months
7. Poor bone-marrow reserve, defined as neutrophil count less than 1.5×109/L or platelet count less than 75×109/L, unless caused by bone marrow infiltration
8. New York Heart Association class III or IV cardiac failure; or Ejection fraction less than 50%;or history of following disease in past 6 months: acute coronary syndrome#acute heart failure#severe ventricular arrhythmia
9. CNS or meningeal involvement
10. Known sensitivity or allergy to investigational product
11. Major surgery within three weeks
12. Patients receiving organ transplantation
13. Patients with secondary tumour, excluding cured (5 years without relapse) in situ Non-melanoma skin cancer. superficial bladder cancer, in situ cervical cancer, Gastrointestinal intramucous carcinoma and breast cancer
14. Presence of Grade III nervous toxicity within past two weeks
15. Active and severe infectious diseases
16. Any potential drug abuse, medical, psychological or social conditions whichmay disturb this investigation and assessment
17. In any conditions which investigator considered ineligible for this study.