A Randomized, Open-Label, Multicenter Phase III Clinical Study of JS203 Plus Chemotherapy Versus Rituximab Plus Chemotherapy in Patients With Relapsed/Refractory Diffuse Large B-Cell Lymphoma

Inclusion Criteria: * Patients must meet all of the following inclusion criteria to be enrolled: * Age range: 18 to 75 years old (inclusive), both male and female are acceptable * ECOG: 0-1； * One of the confirmed histologies below with CD20-positivity: DLBCL, not otherwise specified (NOS), including de novo or histologically transformed from follicular lymphoma (FL)/Marginal Zone Lymphoma(MZL) "Double-hit" or "triple-hit" DLBCL , including de novo or histologically transformed from FL/MZL FL Grade 3B T-cell/histiocyte-rich large B-cell lymphoma * At least one measurable lesion meeting the criteria specified in the Lugano 2014 response assessment； * Acceptable organ function at screening； Exclusion Criteria: * A history of severe allergy to monoclonal antibody therapy (or recombinant antibody-related fusion protein)； * Previously received CD20-CD3 bispecific antibody treatment； * Previous allogeneic hematopoietic stem cell transplantation； * Previous solid organ transplantation * History of autoimmune diseases * Patients with a history of macrophage activation syndrome (MAS)/ hemophagocytic lymphohistiocytosis (HLH) * Patients with a history of progressive multifocal leukoencephalopathy (PML) * A known or suspected history of CNS lymphoma (including primary or secondary) * There is pleural effusion, peritoneal effusion or pericardial effusion that requires treatment (such as puncture or drainage)