First‐line immunotherapy with anti‐PD‐1 antibody for extranodal NK/T‐cell lymphoma: A retrospective study

Summary Anti‐PD‐1 antibody has shown certain effects in patients with newly diagnosed extranodal NK/T‐cell lymphoma (ENKTL). Here, we evaluated the clinical efficacy and safety of first‐line anti‐PD‐1 antibody for the treatment of patients with ENKTL and explored biomarkers for treatment response. The clinical data of 107 patients with newly diagnosed ENKTL were retrospectively analysed. Patients received either first‐line anti‐PD‐1 antibody induction treatment or anti‐PD‐1 antibody combined with asparaginase‐based chemotherapy (immunochemotherapy). We found that immunochemotherapy was an independent prognostic factor for longer PFS ( p < 0.001). The overall response rate and complete remission rate of immunochemotherapy group was higher than immunotherapy induction group (86.11% vs. 62.86% and 72.22% vs. 52.29%, respectively, p = 0.013). We also observed pretreatment CD4/CD8 ratio >0.83 was significant associated with better response and longer PFS in ENKTL patients received first‐line anti‐PD1‐antibody. Plasma copy number of EBV decreased more significantly in patients with CD4/CD8 ratio >0.83 after treatment. PD‐L1 expression was associated with better response and PFS, while elevated plasma IL‐6, IL‐10 and IFN‐γ were associated with poor prognosis. Anti‐PD‐1 antibody treatment showed promising results in newly diagnosed ENKTL patients. The assessment of pretreatment CD4/CD8 ratio in ENKTL seems feasible for identifying responders to anti‐PD‐1 antibody treatment.