Efficacy and safety of PD-1 inhibitor alone or combined with chemotherapy in patients with relapsed or refractory extranodal natural Killer/T cell lymphoma: A retrospective study.

Extranodal natural killer/T cell lymphoma (ENKTL) patients typically face a grim prognosis after relapse or progression following asparaginase-based chemotherapy. Currently, programmed cell death protein-1 (PD-1) immune checkpoint blockade has shown promising efficacy as an optimal regimen for relapsed or refractory ENKTL (rrENKTL) patients. This study retrospectively investigated the efficacy, safety, and factors influencing the survival of 26 rrENKTL patients who underwent monoclonal antibody treatment using PD-1 (Sintilimab or Camrelizumab) alone or combined with chemotherapy from January 2018 to February 2022. The disease control rate was 73.1%, and the objective response rate was 50.0%. 15.4% of the patients achieved complete remission, and 34.6% achieved partial remission (PR). After a median follow-up of 12 (range 3-47) months, the median progression-free survival (PFS) and overall survival (OS) were 6.5 and 13.3 months. The 1-year PFS and OS rate were 23.1% and 53.8%. 96.2% of patients experienced at least one adverse event and 26.9% experienced grade 1-2 immune-related adverse events. PD-1 inhibitor improved rrENKTL patient survival, and the AEs were controlled. We also observed that the prognostic index for NK cell lymphoma including Epstein-Barr virus (EBV) (PINK-E) and the nomogram-revised risk indexz for ENKTL patients could help identify a potentially unfavorable prognosis in this era of immunotherapy. More attention should be paid to the presence of EBV after anti-PD-1 immunotherapy, as it more accurately indicates a poor prognosis.