Chidamide Maintenance for MRD-Positive Double-Expressor DLBCL in First Complete Remission

This is a prospective, multicenter, single-arm, open-label phase 2 study designed to evaluate the efficacy and safety of chidamide maintenance in adults with newly diagnosed double-expressor diffuse large B-cell lymphoma (DLBCL) who achieve complete response after induction therapy but remain ctDNA minimal residual disease (MRD)-positive. Eligible participants will receive oral chidamide 20 mg on Days 1, 4, 8, and 11 of each 21-day cycle. ctDNA MRD will be assessed every 12 weeks. Treatment will continue until two consecutive MRD-negative assessments, disease progression, intolerable toxicity, withdrawal of consent, or completion of 2 years of maintenance. The primary objectives are to evaluate ctDNA MRD negativity and 2-year progression-free survival. Secondary objectives include event-free survival, overall survival, and safety.

Inclusion Criteria: * Histologically confirmed diffuse large B-cell lymphoma, CD20-positive. * Double-expressor lymphoma confirmed by pathology, defined as MYC expression \>=40% and BCL2 expression \>=50% by immunohistochemistry. * Complete response after initial induction therapy. * Age \>=18 and \1. * ctDNA MRD-positive at screening/enrollment. * Life expectancy of at least 6 months, in the opinion of the investigator. * Written informed consent provided before any study-specific procedure. Exclusion Criteria: * Failure to achieve complete response after initial induction therapy. * Prior organ transplantation. * Uncontrolled coagulopathy or active bleeding. * Uncontrolled cardiovascular or cerebrovascular disease, including left ventricular ejection fraction \1.5 x upper limit of normal. * Active hepatitis B not meeting protocol-defined virologic criteria for enrollment; patients with positive HBsAg or positive HBcAb require HBV DNA testing and must meet protocol-specified thresholds. * HIV infection. * Ongoing antitumor therapy for lymphoma or another malignancy. * Drug abuse or chronic alcohol abuse that may interfere with study evaluation. * Psychiatric illness or any condition resulting in inability to comply with the protocol. * Requirement for ongoing treatment with strong or moderate CYP3A inhibitors or inducers; patients exposed to these agents within 7 days before first study dose, or within fewer than 5 half-lives, are not eligible. * Inability to swallow capsules or clinically significant gastrointestinal disorders that may affect drug absorption, including malabsorption syndrome, bariatric surgery, inflammatory bowel disease, or partial/complete bowel obstruction. * Any other uncontrolled medical condition that, in the investigator's judgment, may compromise safety, interfere with oral drug absorption or metabolism, or place the participant at excessive risk.