This study is a multicenter, two-arm, prospective clinical trial, comprising two groups: the observation group and the autologous hematopoietic stem cell transplantation group (Auto-HSCT). It aims to evaluate the efficacy and safety of Auto-HSCT and observation in the treatment of peripheral T-cell lymphoma that has achieved complete response (CR) after first-line therapy. During the screening/baseline period, informed consent will be obtained, and inclusion/exclusion criteria will be verified. Group assignment (Observation vs. Auto-HSCT) will be determined taking into account the patient's preference. The study plans to enroll 80 patients in each group. Data on demographics and medical history will be collected, and assessments including vital signs, physical examination, PET-CT, bone marrow aspiration smear, flow cytometry, and bone marrow pathology will be performed.

Inclusion Criteria:

1. Age between 18 and 70 years (inclusive) at the time of signing the Informed Consent Form (ICF).

2. ECOG Performance Status score of 0 or 1, with no deterioration over the preceding two weeks.

3. Life expectancy of at least 12 weeks.

4. Histologically confirmed diagnosis of PTCL by the central study site according to the 2016 revised WHO classification of lymphoid neoplasms (Swerdlow SH et al. 2016). Eligible histological subtypes are restricted to the following:

   1. Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS)
   2. Anaplastic large cell lymphoma, ALK-negative (ALK- ALCL)
   3. Follicular helper T-cell lymphoma or PTCL with a TFH phenotype (FTCL or PTCL-TFH)

5. Must have achieved a Complete Response (CR) as assessed per the Lugano 2014 classification criteria for lymphoma response after first-line systemic standard therapy (CHOP or a CHOP-like regimen).

6. Adequate hepatic and renal function, defined as:

   1. Hepatic: Serum total bilirubin ≤ 2 × ULN (or ≤ 3.0 × ULN in cases of Gilbert's syndrome or documented baseline liver involvement); Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST) ≤ 2.5 × ULN (or ≤ 5.0 × ULN in cases of liver involvement).
   2. Renal: Serum creatinine ≤ 1.5 × ULN, or creatinine clearance ≥ 50 mL/min as calculated by the Cockcroft-Gault formula or measured.

7. Left Ventricular Ejection Fraction (LVEF) ≥ 50% as measured by Multigated Acquisition (MUGA) scan or Echocardiography (ECHO).

8. Voluntary participation in the clinical study; full understanding and awareness of the study, and having signed the ICF; willingness and ability to comply with and complete all trial procedures.

Exclusion Criteria:

1.Ann Arbor Stage I disease. 2.History of any other malignancy within the past 5 years, except for locally curable malignancies that have been treated with curative intent (e.g., basal cell or squamous cell carcinoma of the skin, superficial bladder cancer, or carcinoma in situ of the prostate, cervix, or breast).

3.Active infection, including:

1. Known active or latent tuberculosis, evidenced by a positive tuberculin (PPD) skin test (where a positive result is defined as an induration >10 mm or per local clinical standards) or findings suggestive of active/latent TB on chest X-ray/CT.

2. Known history of Human Immunodeficiency Virus (HIV) infection and/or AIDS.

3. Chronic active hepatitis B or C infection:

   1. For hepatitis B virus (HBV): Subjects who are HBV DNA positive are excluded. Subjects with undetectable HBV DNA levels are eligible. The upper limit of normal (ULN) for HBV DNA is determined by the local laboratory at each center.
   2. For hepatitis C virus (HCV): Subjects who are HCV RNA positive are excluded. Subjects with undetectable HCV RNA are eligible. The ULN for HCV RNA is determined by the local laboratory at each center.

4. Active viral infections other than hepatitis B or C (e.g., herpes zoster), or cytomegalovirus (CMV) infection.

5. Infection requiring intravenous antimicrobial therapy: evidenced by infection-related hemodynamic instability, worsening or new-onset infectious symptoms/signs, radiologic evidence of a new infectious focus, or persistent fever without localizing signs where infection cannot be ruled out.

6. Positive serological test for Epstein-Barr virus (EBV). 4.Poorly controlled cardiac symptoms or diseases, such as: i. Heart failure > New York Heart Association (NYHA) Class II. ii. Unstable angina. iii. Myocardial infarction within the past year. iv. Clinically significant supraventricular or ventricular arrhythmia requiring treatment or intervention.

5.Pregnant or lactating women, and subjects of childbearing potential unwilling to employ effective contraception.

6.Patients with psychiatric disorders or those unable to provide informed consent.

7.Any other condition which, in the investigator's judgment, makes the subject unsuitable for participation in this study

The patients with peripheral T-cell lymphoma that has achieved complete response (CR) after first-line therapy.