Outcomes of Patients With Newly Diagnosed AML and Hyperleukocytosis

AML presenting with hyperleukocytosis is associated with poor outcomes. We aim to understand the factors associated with early mortality and overall survival (OS) to help guide management and improve early mortality.

We retrospectively reviewed data from 129 consecutive patients with newly diagnosed AML and a WBC count ≥100 × 10⁹/L between January 2010 and April 2020. Logistic regression models estimated odds ratios for 4-week mortality. Cox proportional hazard models estimated hazard ratios for OS.

The median age was 65 years (range, 23-86); the median WBC was 146 × 10⁹/L (range, 100-687). Seventy-five (58%) patients had clinical leukostasis (CL). FLT3, NPM1, and RAS pathway mutations were detected in 63%, 45%, and 27% of patients, respectively. Cytoreduction consisted of hydroxyurea in 124 (96%) patients, cytarabine in 69 (54%), and leukapheresis in 31 (24%). The cumulative 4-week and 8-week mortality rates were 9% and 13%, respectively, all in patients age 65 years and older. By multivariate analysis, older age, CL, and thrombocytopenia <40 × 10⁹/L were independently associated with a higher 4-week mortality rate. After a median follow-up of 49.4 months, the median OS was 14.3 months (95% CI, 7 to 21.6), with 4-year OS of 29%. Age 65 years and older, CL, tumor lysis syndrome, elevated LDH ≥2,000 U/L, elevated lactate ≥2.2 mmol/L, and poor-risk cytogenetics were independent factors associated with worse OS.

Hyperleukocytosis is a life-threatening hematologic emergency. Early recognition and intervention including cytoreduction, blood product support, antibiotics, and renal replacement therapy may help mitigate the risk of morbidity and early mortality.