A prospective, single center, randomized, clinical controlled study to evaluate the efficacy and prognosis differences between precision treatment based on plasma cfDNA testing results and the current conventional diagnostic and treatment practices for DLBCL patients.

This study is initiated by researchers and is a prospective, single-center, randomized, clinical controlled study. The study subjects are newly diagnosed DLBCL patients with plasma cfDNA positivity (defined as positive for point mutations, CNV, IgH-related fusion, or IG clonal rearrangement). After achieving complete metabolic remission (Lugano response assessment criteria) following 6 cycles of R-CHOP-like chemotherapy, patients undergo plasma cfDNA testing upon enrollment. Plasma cfDNA-negative patients (Group 1) continue to receive monotherapy with rituximab for 2 cycles, while plasma cfDNA-positive patients are randomly assigned to Group 2 and Group 3. Group 2 patients continue monotherapy with rituximab for 2 cycles, and Group 3 patients receive the original regimen for 2 cycles. Plasma cfDNA testing is performed again for all three groups after completion of the entire treatment. Patient progression-free survival (PFS) is observed for 2 years. After treatment completion, follow-up visits are scheduled every 3 months for a total of 24 months.

Research Objective: Evaluate the efficacy and prognosis differences between precision treatment based on plasma cfDNA testing results and the current conventional diagnostic and treatment practices for DLBCL patients.

Expected Results: Determining subsequent treatment based on plasma cfDNA MRD results at the end of DLBCL patient treatment is expected to aid in identifying high-risk patients for early relapse and improving their prognosis.

Inclusion Criteria:

• Age ≥ 18 years, gender not specified.
• Newly diagnosed patients with diffuse large B-cell lymphoma (DLBCL) confirmed by histopathological examination. Patients should test positive for plasma cfDNA before treatment (defined as positive for point mutations, CNV, IgH-related fusion, or IG clonal rearrangement) and achieve complete metabolic remission after 6 cycles of R-CHOP chemotherapy (evaluated by Lugano response assessment criteria).
• Patients for whom the researcher predicts a life expectancy of >6 months.
• Signed informed consent form.

Exclusion Criteria:

• Patients who have undergone autologous stem cell transplantation.
• Patients with a history of other malignant tumors, except for basal cell carcinoma of the skin or in situ cervical cancer.
• Patients with uncontrolled cardiovascular diseases, coagulation disorders, connective tissue diseases, severe infectious diseases, and other such conditions;
• Primary central nervous system lymphoma.
• Patients with mental illness or others known or suspected to be unable to fully comply with the study protocol.
• Pregnant or lactating women.
• HbsAg-positive patients who need to undergo HBV-DNA testing and can only be included if they seroconvert. Additionally, if the HbsAg test is negative but the HBcAb test is positive (regardless of HbsAb status), HBV-DNA testing is also required. If the result is positive, inclusion is possible only after seroconversion.
• HIV-infected individuals.
• Other concurrent and uncontrolled diseases that researchers believe may affect the medical condition of patients participating in the study.