To evaluate the efficacy and safety of bendamustine combined with chidamide and lenalidomide in R/R PTCL patients.

This study will enroll relapsed/refractory (R/R) peripheral T-cell lymphoma (PTCL) patients aged over 18 years who have received at least one line of prior systemic therapy. Participants will receive combination therapy with bendamustine, chidamide, and lenalidomide (BCL regimen), with dose reduction for patients >70 years old. After 4 cycles of BCL regimen, patients demonstrating stable disease(SD) or progressive disease (PD) will be withdrawn from the study. Patients achieving partial remission(PR) or complete remission(CR) will receive another 2 cycles of BCL regimen followed by stratification treatment as followings:

Cohort 1 (ASCT-eligible): Responders will proceed to autologous stem cell transplantation (ASCT) consolidation

Cohort 2 (ASCT-ineligible): Responders will receive oral chidamide maintenance therapy (minimum 2 years or until progression/unacceptable toxicity)

Inclusion Criteria:

1. Age ≥18 years, male or female not limited;
2. Patients must have the capacity to understand and willingly provide written informed consent;
3. ECOG score 0-3 points;
4. Expected lifespan>3 months;
5. Patients with peripheral T-cell lymphoma (PTCL) confirmed by histopathology/cytology using the 2022 World Health Organization (WHO) Classification of Diseases;
6. Measurable lesions with a short diameter of ≥15mm defined by PET/CT;
7. R/R PTCL: patients with at least previous first-line treatment failure and no prior exposure to chidamide, lenalidomide and bendamustine;
8. Any non-hematological toxicity, except hair loss, associated with prior treatment in patients with R/R disease, as per NCI CTCAE version 5.0, must be managed and resolved to at least grade 1;
9. Appropriate organ function: Cardiac function: ejection fraction ≥ 50%, asymptomatic arrhythmia; Liver function: alanine aminotransferase and aspartate aminotransferase ≤ 2 times the upper limit of normal, total bilirubin<2 times the upper limit of normal; Renal function: serum creatinine clearance rate ≥ 80 mL/min, creatinine<160 umol/l; Pulmonary function: Without oxygen inhalation, SPO2>90%, FEV1, FVC, and DLCO ≥ 50% predicted values;
10. Adequate bone marrow reserve is defined as: Hemoglobin ≥ 9g/dL, Platelet count ≥ 70 × 10 ^ 9/L, The absolute value of neutrophils is ≥ 1.0 × 10 ^ 9/L, If accompanied by bone marrow invasion, platelet count ≥ 50 × 10 ^ 9/L, absolute neutrophil count ≥ 0.75 × 10 ^ 9/L, The number of CD34+cells is ≥ 2.0 × 109/kg;
11. Subjects with fertility or potential for fertility must be willing to undergo contraception from the date of registration in this study until the study follow-up period;
12. Patients with good compliance.

Exclusion Criteria:

1. Patients with R/R disease previously used chidamide, lenalidomide and bendamustine, or received any other anti-tumor therapy within 4 weeks.
2. Patients enrolled in another clinical study within 4 weeks;
3. HIV infection and/or active hepatitis B or C;
4. Uncontrolled active infections;
5. Severe liver and kidney dysfunction (alanine aminotransferase, bilirubin, creatinine>3 times the upper limit of normal);
6. Existence of organic heart disease or severe arrhythmia, leading to clinical symptoms or abnormal heart function (NYHA functional class ≥ 2);
7. Simultaneously present other tumors that require treatment or intervention;
8. Previous or current history of vascular embolism;
9. Pregnant or lactating women;
10. In a state of severe immune suppression;
11. Other psychological conditions that hinder patients from participating in research or signing informed consent forms.
12. Patients are unlikely to complete all protocol study visits and procedures or do not meet the requirements for study participation.