[Programmed cell death-1 inhibitor combined with rituximab in refractory or relapsed diffuse large B-cell lymphoma: a preliminary efficacy and safety analysis].

Objective: To investigate the efficacy and safety of programmed cell death protein-1 (PD-1) inhibitor combined with rituximab in the treatment of refractory or relapsed diffuse large B-cell lymphoma (rrDLBCL) patients. Methods: The efficacy and safety of rrDLBCL patients treated with PD-1 inhibitor combined with rituximab as salvage therapeutic regimen after initially treated with rituximab, cyclophosphamide, anthracycline, vincristine and prednisone (R-CHOP) regimen in Cancer Hospital, Chinese Academy of Medical Science & Peking Union Medical College from October 2018 to Janurary 2020 were retrospectively analyzed.Patient who received at least one dose of PD-1 inhibitor combined with rituximab treatment and obtained the efficacy and safety evaluation were included. Results: A total of 22 patients were enrolled in this study. The median age was 51.5 years and the median number of prior treatment regimen was 2. The median time to progression (TTP) for the initial R-CHOP treatment was 9.3 months and the median interval time of rituximab administrations between the previous and the research regimen was 5.5 months. Patients were classified as germinal center B cell (GCB) origin (n=8), non-GCB origin (n=9) and primary mediastinal large B cell lymphoma (PMBCL, n=5). Four patients were double-expression lymphoma, one patient were triple-hit lymphoma. Nine patients had PD-L1 immunohistochemical staining and the proportion of PD-L1 positive tumor cells were 1%-90% for eight patients and negative for one patient.The objective response rate (ORR) and complete response rate (CR) were 72.7% (16/22) and 13.6% (3/22), respectively. The median progression free survival (PFS) was 8.0 (95%CI: 7.0-14.5) months, and overall survival (OS) was not reached. For the 17 patients of non-specific DLBCL, the ORR was 64.7% (11/17), the estimated median PFS was 4.0 (95%CI: 0-8.8) months, the 1-year PFS and OS rates were 39.2% (95%CI: 19.4%-43.4%)and 81.3% (95%CI: 71.4%-91.1%), respectively. All of 5 PMBCL cases achieved ORR, among them, one case was CR and 4 cases were partial responase (PR), and their PFS were 16.4, 9.3, 8.3, 7.9and 3.0 months, respectively. One patient had National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) version 5.0 grade 3 hypophysitis and one patient had NCI CTCAE grade 3 interstitial pneumonia. Conclusion: For rrDLBCL patients who have underwent rituximab treatment previously, PD-1 inhibitor combined with rituximab regimen shows a promising efficacy and tolerability, which can be a potential treatment option.