Aggressive natural killer cell leukemia: diagnosis, treatment recommendations, and emerging therapies

Integration of anti-PD-1 antibody into chemotherapeutic regimens improved the outcome of aggressive NK cell leukemia: a single-center retrospective real-world analysis

Background

Aggressive natural killer (NK) cell leukemia (ANKL) is a rare NK cell neoplasm associated with Epstein-Barr virus (EBV) infection. Programmed cell death protein 1 (PD-1) blockade, which is successful in extranodal NK/T-cell lymphoma and EBV-related hemophagocytic lymphohistiocytosis, is considered to have a potential role in managing ANKL.

Objectives

This study aims to characterize ANKL clinically and evaluate the prognostic impact of anti-PD-1 antibody treatment.

Methods

We retrospectively analyzed the clinical characteristics and treatment regimens of ANKL patients from March 2009 to October 2023 in a single center. Data on clinical characteristics, treatment regimens and prognosis were collected from medical records. Overall survival (OS) of different risk groups was analyzed by Kaplan-Meier method. The least absolute shrinkage and selection operator (LASSO)-penalized Cox regression was used to identify the potential prognostic factors of ANKL.

Results

From March 2009 to October 2023 a total of 71 ANKL were retrieved with an OS of 2.0 months. Seven patients (9.9%) received PD-1 antibodies combined with various chemotherapies; thirty-five patients (49.3%) received asparaginase as part of chemotherapy; and eight patients (11.3%) received allogeneic HSCT after induction chemotherapy. Among patients who did not undergo allogeneic hematopoietic stem transplantation (HSCT), patients who received PD-1 antibodies as part of chemotherapy exhibited a superior OS than those without PD-1 antibodies (5.4 vs 1.6 months, p=0.035). The 1-year OS rate was 43% in the PD-1 subgroup compared with only 4% in the non-PD-1 subgroup. LASSO-Cox multivariate analysis revealed that PD-1 antibodies-containing regimens were associated with better survival (hazard ratio [HR]=0.349, 95% CI: 0.145~0.840, p=0.019). So was it with HSCT and asparaginase (HR=0.267, 95% CI=0.101~0.701 and HR=0.355, 95% CI=0.206~0.613, respectively).

Conclusion

ANKL still had a poor outcome in the past decade. Integration of anti-PD-1 antibody into chemotherapeutic therapy significantly improved the survival of ANKL. The prolonged survival attributed to PD-1 blockade could provide critical opportunities for patients awaiting HSCT.

The superiority of Epstein-Barr virus DNA in plasma over in peripheral blood mononuclear cells for monitoring EBV-positive NK-cell lymphoproliferative diseases

Epstein-Barr virus (EBV), characterized as an omnipresent virus, has been found able to infect NK cells and leads to NK-cell type EBV-positive lymphoproliferative diseases (EBV-NK-LPDs). We retrospective analysed 202 EBV-NK-LPDs (including 64 CAEBV-NK, 27 ANKL, and 111 ENKTL) patients' relationships between EBV DNA copies laboratory test results and clinical features. In CAEBV-NK cohort, EBV DNA loads in either plasma or PBMCs had significant differences between the active state and the inactive state. Receiver operating characteristic (ROC) curves were used to measure the diagnosis accuracy of EBV DNA copies. After comparing the area under the curve (AUC), EBV DNA loads in plasma had significantly higher accuracy in distinguishing disease activation than in PBMCs. Therefore, we propose redefining CAEBV-NK diagnosis criteria as increased EBV DNA copies in plasma (over 7.1×10² copies/ml) instead of in peripheral blood. In ANKL and ENKTL cohorts, patients who received effective therapy had significantly lower EBV DNA copies in plasma & PBMCs than in those with ineffective therapy. The significant and consistent decline indicated EBV DNA loads in plasma being a more sensitive biomarker in monitoring EBV-NK-LPDs therapy responses. Hemophagocytic lymphohistiocytosis (HLH) can occur secondary to EBV-NK-LPDs, mostly associated with a poor prognosis, so we try to estimate the combination of HLH by monitoring EBV DNA copies. When comparing the ROC curves of EBV DNA copies, EBV DNA loads in plasma had higher diagnosis accuracy. When the copies level over 4.16×10³ copies/ml, it might indicate combining with HLH. This article is protected by copyright. All rights reserved.

Aggressive Natural Killer Cell Leukemia in an Adolescent Patient: A Case Report and Literature Review

Aggressive natural killer cell leukemia (ANKL) is a rare malignant tumor, especially uncommon in children. ANKL has very aggressive clinical course and bad prognosis and is usually caused by Epstein-Barr virus infection. ANKL often has clinical manifestations of hemophagocytic lymphohistiocytosis (HLH) and can be easily treated as HLH, which might complicate this aggressive disease. Here we report an ANKL in adolescent whose clinical presentation was highly aggressive and response to L-asparaginase containing chemotherapy was very bad. Early-onset Flow cytometry of peripheral blood and bone marrow help make the diagnosis.