Impact Of ELN Risk Stratification, Induction Chemotherapy Regimens And Hematopoietic Stem Cell Transplantation On Outcomes In Hyperleukocytic Acute Myeloid Leukemia With Initial White Blood Cell Count More Than 100 × 10⁹/L

Background: Hyperleukocytic acute myeloid leukemia (AML) (initial white blood cell count ≥ 100 × 10⁹/L) is a clinical emergency often accompanied by leukostasis syndrome, tumor lysis syndrome (TLS), and disseminated intravascular coagulation (DIC), with a poor clinical prognosis. The aim of this study retrospectively analyzed the clinical features of hyperleukocytic AML, focusing on high-risk factors affecting prognosis, the selection of initial induction therapy, and the impact of hematopoietic stem cell transplantation (HSCT) on prognosis.

Patients and methods: A total of 558 AML patients at our center from January 2013 to December 2017 were diagnosed, and 52 (9.32%) patients presented with hyperleukocytosis were retrospectively reviewed.

Results: The 3-year overall survival (OS) rate in the 15-39 years old and 40-60 years old group was 58.8% and 25.4%, respectively; the longest survival time in patients aged >60 years was only 8 months, and the 8-month OS rate was 8.3% (p=0.002). The 3-year OS rate of the patients in the favorable risk group, intermediate risk group and high risk group, according to the 2017 ELN risk stratification, was 50%, 28.0%, and 29.5%, respectively (p=0.374). The 3-year OS rate of patients carrying CEBPA or NPM1 mutation and those with FLT3-ITD or MLL mutation was 37.5% and 30.0%, respectively (p=0.63). The 3-year OS rate of patients employing an induction regimen of a standard IA regimen was 58.4%, and of those employing a non-standard IA regimen was 22.2% (p=0.065). The 3-year OS rate of the transplantation patients reached 73.8%, while the 9-month OS rate of patients without transplantation was 11.4% (p<0.001).

Conclusion: This study suggest that hyperleukocytosis is an independent risk factor for AML patients, regardless of the risk stratification based on cytogenetic or molecular abnormalities. Age is the main factor influencing the prognosis of hyperleukocytic AML. The use of a standard IA regimen and HSCT can significantly improve the patient's prognosis.