Purpose: To explore the impact of PD-1 maintenance therapy on DLBCL patients’ relapse-free survival (RFS).

Methods: A retrospective analysis of patients with DLBCL who were admitted to the Department of Hematology and Oncology in Cancer Hospital, Chinese Academy of Medical Sciences, Shenzhen center who achieved complete remission after induction chemotherapy between January 2018 and July 2019. Forty-five patients who received PD-1 inhibitor maintenance therapy were set as the treatment group. Forty-five patients who did not undergo maintenance treatment during the same period were selected as the control group.The base levels of the two groups of patients were similar. The 2-year RFS rate of the two groups was compared. The correlation between the adverse prognosis factors of the patients and the RFS rate was performed subgroup analysis.

Results: A total of 90 patients with DLBCL with CR after treatment (45 per group) were included in this retrospective analysis. There were 25 males and 20 females in the treatment group with a median age of 49.7 (21–78) years old, and 13 cases were above 60 years old. There were 23 males and 22 females in the control group with a median age of 48.8 (26–76) years old, and 13 cases were above 60 years old. Patients in the treatment group received single-agent PD-1 inhibitors (five pembrolizumab cases, six nivolumab cases, 16 sintilizumab cases, and 18 teriprizumab cases). The median duration of treatment for patients was 13.2 (6–24) months. Six patients (6/45,13.3%) progressed and changed other treatment options to continue treatment, and three patients died from disease progression (3/45,6.7%). None of the patients in the treatment group discontinued the drug due to treatment toxicity and other factors. In the control group, eleven patients (11/45,24.4%) progressed and received other treatment options to continue treatment, and seven patients (7/45,15.6%) due to disease progression.The deadline for follow-up was July 31, 2021. The median follow-up time of the control group was 31.5 (15–42) months, and the median follow-up time of the treatment group was 30.2 (12–42) months. The control group showed a certain survival improvement trend in OS and RFS compared to the treatment groups, but it did not reach statistical significance. The 2-year RFS rates of the treatment and control groups were 86.7% VS 75.6% (p=0.178). A single factor analysis showed that patients with IPI scores ≥ 3 receiving PD-1 inhibitor maintenance treatment can improve their 2-year RFS (72.2% VS 30.8%, P=0.022), there is a significant statistical difference . For non-GCB patients, the 2-year RFS of the treatment group can reach 88.5%, while the 2-year RFS of the control group is 62.5%, which is statistically significant (P=0.032).

Conclusion: Maintenance treatment with PD-1 inhibitors can improve the 2-year RFS rate of patients with IPI score ≥ 3 and non-GCB DLBCL. This prompts the potential advantage of PD-1 inhibitors in DLBCL maintenance treatment. However, longer follow-ups remain needed to obtain more definite data.