Selinexor in Combination With R-CHOP as the First-line Therapy for TP53-mutated DLBCL Patients (Smart Trial)

Inclusion Criteria: * Subjects fully understand and voluntarily participate in this study and sign informed consent. * Aged ≥18 and ≤80 years, no gender limitation. * Histologically confirmed DLBCL with TP53 mutations (allowing transformed or concurrent indolent B-cell non-Hodgkin lymphoma) * No prior systemic anti-lymphoma therapy; prior local radiotherapy alone is permitted. * There must be at least one measurable or evaluable lesion that meets the evaluation criteria for Lugano 2014 lymphoma. * Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) 0-2. * Expected survival ≥ 3 months. * Adequate function of bone marrow, liver, and kidney. Exclusion Criteria: * DLBCL with Hodgkin lymphoma, T-cell lymphoma, or other non-B-cell lymphoma; Richter transformation. * DLBCL with central nervous system invasion. * The patients had previously received XPO1 inhibitors. * The patients have contraindications to any drug in the combined treatment. * Patients with chronic active hepatitis B or active hepatitis C. If the background hepatitis B surface antigen (HBsAg) and/or hepatitis B core Antibody (HBcAb) or hepatitis C Virus (HCV) antibody are positive, the further determination for Hepatitis B Virus (HBV) DNA (no more than 2500 copies /mL or 500 IU/mL) and HCV RNA (no more than the lower limit of the assay) can be included. The patients with HBsAg and/or HBcAb positive need to receive anti-HBV drugs. * Patients with the infection of human immunodeficiency virus (HIV) and/or acquired immunodeficiency syndrome. * Inability to swallow tablets, presence of malabsorption syndrome, or any other gastrointestinal disease or dysfunction that may affect the absorption of the study drug. * Pregnant and lactating women and subjects of childbearing age who do not want to use contraception. * Mentally ill persons or persons unable to obtain informed consent. * Any condition deemed unsuitable by the investigator.