This study aims to investigate the efficacy and safety of PET regimen combined with Chidamide for angioimmunoblastic T cell lymphoma patients.

Patients enrolled in the trial would be given prednisone, etoposide, thalidomide and Chidamide, and the response and side effects are observed and documented.

Inclusion Criteria:

1. Pathologically diagnosed as angioimmunoblastic T cell lymphoma (diagnosed by pathologic department in IIIA hospitals or verified by certified institutions), immunohistochemistry should include: CD3, CD4, CD8, CD20, CD10, CD21, CD35, Bcl6, CXCL13, EBER, PD-1, Ki67.
2. At least on measurable focus (≥1.0*1.0cm by imaging), or at least one evaluable focus;
3. Age 18-75 years, both male and female;
4. ECOG 0-2, KPS≥ 70points;
5. Expected survival ≥3 months;
6. Peripheral blood neutrophil count ≥1.5×10^9/L, platelet count≥ 75×10^9/L, Hb≥ 90g/L;
7. Liver function: bilirubin ≤1.5 times of the normal maximum; AST、ALT≤2 times of the normal maximum (for patients with liver infiltration AST、ALT≤3 times of the normal maximum); renal function: blood creatinine ≤2 times the normal maximum;
8. Negative random pregnancy test for fertile women patients within 7 days before enrollment;
9. No radiation therapy, chemotherapy, targeted therapy nor hemopoietic stem cell transplantation within 4 weeks before enrollment;
10. No anti-tumor therapy at enrollment, including herbal therapy, immunotherapy and biologic therapy, symptomatic treatment is not within this range;

Exclusion Criteria:

1. Women during pregnancy or lactation, and fertile women that are not willing to take contraceptive measurements;
2. Patients with other malignant tumors simultaneously that have not been effectively controlled;
3. Patients with history of using HDAC inhibitors;
4. Patients who are allergic to medicine used in the trial, or have metabolic disorders toward these medicine;
5. Patients with severe active infection;
6. Patients with HIV or syphilis infection;
7. Patients with prolonged QT interval (male > 450ms，female > 470ms), or chronic heart failure patients with level III or IV cardiac function; or those have the following heart disease within 6 months before enrollment: acute coronary syndrome, acute heart failure (heart function level III or IV), distinctive ventricular arrhythmias (prolonged ventricular tachycardia, ventricular fibrillation, etc);
8. Patients with history of organ transplantation;
9. Patients with history of thrombosis and embolism;
10. Patients with mental disorders or those who are unable to sign a written consent;
11. Patients with drug abuse or long-time alcoholism that may influence the result of the trial;
12. Patients who do not have capacity of legal transactions;
13. Patients currently in other clinical trials;
14. Those who are recognized as inappropriate for the trial by the investigators;

After the trial is finished, all the data would be available at the principle investigator's location.