The Purpose of This Study is to Compare the Efficacy, Safety, Immunogenicity and Pharmacokinetics between TQB2303 and Rituximab in Combination With CHOP in Previously Untreated Patients with Diffuse Large B-cell Lymphoma

Inclusion Criteria:

1. Untreated CD20-positive DLBCL patients confirmed by histopathology or cytology.
2. 18 years to 75 years; Male or female patients.
3. International Prognostic Index (IPI) score of 0 to 2.
4. Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2.
5. More than 6 months life expectancy judged by the researchers.
6. At least one measurable lesions: for nodal tumor mass, more than 1.5 cm in the long axis and more than 1.0 cm in the short axis; for extranodal tumor mass, more than 1.0 cm in the long axis.
7. left ventricular ejection fraction (LVEF) measured by the Cardiac echocardiography greater than or equal to 50%.
8. Adequate hematologic function, no matter the bone marrow was attacked or not, as follows:absolute neutrophil count (ANC) ≥1.5×10^9/L and platelet count≥75×^9/L.
9. Understood and Signed an informed consent form.

Exclusion Criteria:

1. Known allergic reactions against human or murine monoclonal antibody, murine products, or foreign proteins.

2. Known allergic reactions against any component of CHOP regimen.

3. Previous treatment for DLBCL, including chemotherapy, immunotherapy, partial radiotherapy for lymphoma, or surgical treatment (excluding tumor mass biopsies and surgical resection for non-lymphoma lesions), or prior use of any monoclonal antibody within 3 month.

4. T-cell/histiocyte-rich large B-cell lymphoma, Primary DLBCL of the CNS, Primary cutaneous DLBCL, leg type, EBV-positive DLBCL of the elderly (EBV + DLBCL), EBV-positive DLBCL of the elderly (EBV + DLBCL), DLBCL associated with chronic infammation, Lymphomatoid granulomatosis, Primary mediastinal (thymic) large B-cell lymphoma (PMBL), ALK-positive large B-cell lymphoma, ALK-positive large B-cell lymphoma, ALK-positive large B-cell lymphoma, high-grade B-cell lymphoma (high-grade B-cell lymphoma with MYC, with or without concurrent in BCL2 and/or BCL6 gene rearrangements, high-grade B-cell lymphoma, NOS), B-cell lymphoma, Not categorizable, Characteristics between DLBCL and classical Hodgkin's lymphoma, transformed DLBCL, DLBCL secondary central nervous system invasion;

5. Other malignant tumors that have been or are currently suffering (healed skin basal cell carcinoma or cutaneous squamous cell carcinoma, or cutaneous melanoma or cervical carcinoma in situ).

6. Significantly poorly controlled diseases that can affect adherence to the study protocol, such as severe cardiovascular disease (such as the New York Heart Association class III or IV heart disease, myocardial infarction or unstable arrhythmia in the last 6 months or Unstable angina, severe hypertension, peripheral nervous system or central nervous system disease;

7. Patients with a history of progressive multifocal leukoencephalopathy.

8. Continuous corticosteroid treatment being received, dose >30 mg/day prednisone or equivalent dose of corticosteroids ≥10 days.

9. Participation in another interventional clinical trial in the past 3 months.

10. Patients who received or underwent major surgeries within 28 days prior to enrollment, or patients with unsurgical wounds.

11. Treated with transfusion, erythropoietin (EPO), granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) within 14 days prior to enrollment.

12. Vaccination within 28 days or planned prior to enrollment.

13. Appearing the following laboratory abnormal values.

    1. Coagulation function: partial prothrombin time (PTT) or activated partial thromboplastin time (aPTT) or international normalized ratio (INR) > 1.5 times ULN without anticoagulant therapy.
    2. Liver function: total bilirubin (TBIL) > 1.5 times the upper limit of normal (3 times the upper limit of normal value when the liver is invaded), alanine aminotransferase (ALT) and / or aspartate aminotransferase (AST) > 2.5 times the upper limit of normal value (>5 times the upper limit of normal value when the liver is invaded)
    3. Renal function: serum creatinine (Cr) > 1.5 times the upper limit of normal value.

14. an active infection at the time of enrollment, or any major infection events that affected the enrollment of the subjects determined by the investigator within 28 days (except for neoplastic fever).

15. Suspected active or latent tuberculosis infections.

16. HBsAg positive and/or HBcAb positive and HBV DNA positive.

17. HCV antibody and HCV-RNA positive; or HIV positive patients.

18. Pregnancy or breast feeding. Companion for women of childbearing age or women of childbearing age,who reluctant to take appropriate contraceptive methods within one year after the last treatment of the study;Pregnancy before pregnancy screening, the women who blood / urine results were positive.

19. Patients that researchers deem as not appropriate to enter the study.