Sintilimab Plus R-GemOx as Second-line Salvage Therapy in Patients With R/R DLBCL

This study evaluates the addition of Sintilimab to current 2nd line salvage therapy of Rituximab, Gemcitabine and Oxaliplatin (R-GemOx) for patients with relapsed or refractory Diffuse Large B-Cell Lymphoma (DLBCL). All patients will receive four cycles of sintilimab plus R-GemOx. Afterwards, 1) patients who achieve CR assessed by PET-CT and are eligible for autologous stem cell transplantation (ASCT) will undergo ASCT. After transplantation, patients will receive sintilimab monotherapy up to 8 cycles or until disease recurrence and progression, death, intolerance and toxicity, withdrawal of informed consent, or other reasons specified in the protocol. 2) Patients who achieve CR assessed by PET-CT and are not eligible for ASCT will directly receive sintilimab monotherapy as maintenance treatment for a maximum of 8 cycles as described above. 3) Patients achieved PR, SD or PD assessed by PET/CT will withdraw from this study and receive proper treatment based on investigator's decision.

Rituximab is a chimeric mouse/human monoclonal antibody that binds to CD20, on pre-B and mature B lymphocytes and eliminates these cells potentially via a number of different mechanisms. The R-GemOx regimen has been adopted by numerous medical institutions internationally as therapy for older patients or comorbid patients with relapsed or refractory DLBCL and as a back-bone for the investigation of novel therapies in combination with chemotherapy. The cytotoxic T-lymphocyte co-receptor PD-1 has been extensively studied and is recognized to provide critical inhibitory signals that down-regulate T-cell function and provides a mechanism for immune evasion for tumors. PD-L1, the ligand of PD-1 is expressed on DLBCL tumor cells, along with infiltrating non-malignant cells, primarily macrophages, with PD-1 expressed on tumor infiltrating lymphocytes (TILs). Sintilimab targets programmed PD-1 on tumor cells and prevents interaction with either PD-1 receptor or B7.1 (CD80), both of which function as inhibitory receptors expressed on T cells. Interference of the PD-L1:PD-1 and PDL1:B7.1 interactions may enhance the magnitude and quality of the tumor-specific T-cell response through increased T-cell priming, expansion, and/or effector function. This study of sintilimab in combination with rituximab, gemcitabine and oxaliplatin aims to address the unmet clinical need of patients with relapsed and refractory DLBCL. It is based upon a sound mechanistic approach, investigating the activity of novel agents and will aim to compressively explore biomarkers of response. The primary objective will be the complete response rate (CRR) of this salvage therapy. A maintenance phase of sintilimab will be added as this may induce an on-going T-cell response to neo-antigens released as a result of previous treatment.