This is a prospective phase II clinical trial to observe the efficacy and safety of Chidamide as a single-agent treatment in patients with relapsed or refractory B-cell Non-Hodgkin's Lymphoma (NHL).

Patients with relapsed /refractory aggressive B cell lymphoma usually have a poor prognosis. These patients cannot be treated successfully or tolered with the conventional chemotherapy. Epigenetic changes in B-cell lymphoma. Thus, epigenetic agents may offer potential improvment of clinical outcomes. Chidamide is a new type of oral histone deacetylase inhibitor. Our exploratory research found that Chidamide was effect in some relapsed /refractory B cell lymphoma patients

. Thus, we will evaluate the efficacy and safety of Chidamide in the patients with aggressive relapsed refractory B cell lymphoma failed from second line chemotherapy.

Inclusion Criteria:

1. Diagnosed as B-cell Non-Hodgkin's Lymphoma (NHL) according to "2008 WHO classification of tumors of haematopoietic and lymphoid tissues", including Diffuse Large B-Cell Lymphoma (DLBCL), Mantle Cell Lymphoma (MCL), transformed indolent lymphoma (TL), and other subtypes that investigators consider to be appropriate to be enrolled;
2. Patients achieved CR or PR in previous cytotoxic chemotherapy, and relapsed later than 6 months after remission;
3. Patients with DLBCL, FL grade3, MALT, LPL and SLL received at least two chemotherapy regimens, and Patients with FL grade1-2 received at least three chemotherapy regimens;
4. At least one measurable lesion with a longest diameter >1.5cm or a short axis >1.0cm;
5. Age18-75 years;
6. ECOG performance status 0-2;
7. Life expectancy no less than 3 months;
8. Functions within 7 days prior to enrollment: Blood routine test: Hb ≥ 80g/L, absolute neutrophil count ≥1.5 × 109/L, platelet ≥60 × 109/L; Total bilirubin ≤ 1.5 times of normal maximum, ALT/AST≤ 2.5 times of normal maximum, for patients with liver metastasis ALT/AST≤ 5 times of normal maximum; serum creatinin≤1.5 times of normal maximum or CCr≥ 60ml/min;
9. LVEF ≥ 50% by echocardiography;
10. Contraception during and 4 weeks after the study for patients at child bearing age;
11. Patients have signed the Informed Consent Form.

Exclusion Criteria:

1. Patients received Chidamide treatment within 6 months prior to enrollment;
2. Patients with Burkitt Lymphoma, B-lymphoblastic lymphoma, central nervous system lymphoma and HIV-Associated Lymphoma;
3. Patients with a "currently active" second malignancy;
4. Patients not recovered from non-hematologic toxicities within 4 weeks prior to enrollment due to chemotherapy, radiation and immunotherapy;
5. Patients receiving or received corticosteroids within 2 weeks prior to enrollment;
6. Patients with cumulative life time dose of Doxorubicin > 450mg/m2;
7. Patients who have been treated with any investigational drug within 4 weeks prior to enrollment;
8. Women during pregnancy or lactation;
9. Patients with active infection, medical conditions, or mental disorders;
10. Patients with active infection of HBV, HCV or HIV;
11. Congestive heart failure (NYHA grade III/IV), myocardial infarction within 6 months, QTc elongation with clinical significance (≥480ms), hypertension BP≥150/100 mmHg and symptomatic coronary heart disease that require treatment;
12. Patients with drug abuse, long term alcoholism that may impact the results of the trial;
13. Non-appropriate patients for the trial according to the judgment of the investigators.