Disease Subtype and Procedural Determinants of Leukapheresis Efficacy: A Retrospective Single-Center Study.

Background/Objectives: Therapeutic leukapheresis is widely used to manage hyperleukocytosis in hematologic malignancies, yet the factors determining its efficacy remain incompletely defined. We aimed to identify clinical, biochemical, and procedural determinants of leukapheresis efficacy in a single-center cohort. Methods: We retrospectively analyzed 125 leukapheresis procedures performed in adult patients with hematologic malignancies between March 2012 and June 2026. At our institution, emergency leukapheresis is performed before the initiation of cytoreductive therapy, so all first procedures were treatment-naïve (repeat procedures could follow cytoreductive therapy). The primary endpoint was the white blood cell (WBC) reduction rate (%). Secondary endpoints were ≥30% and ≥50% reduction. Predictors of reduction were identified using univariate tests and multivariable regression, with within-patient correlation accounted for using cluster-robust standard errors, and pre- versus post-procedure biochemical changes were assessed for paired samples. Results: The median WBC reduction was 47.9%; ≥30% and ≥50% reduction were achieved in 75% and 42% of procedures, respectively. Reduction differed significantly by diagnosis (p < 0.001), being highest in ALL (57.4%) and lowest in CML (18.6%). In multivariable analysis, processed volume (β = 0.004, p < 0.001), inlet rate (β = -0.43, p < 0.001), acute leukemia (β = 10.4, p = 0.040), and baseline platelet count (β = -0.03, p = 0.036) were independent predictors. Leukapheresis significantly reduced LDH and uric acid levels (both p < 0.001). Conclusions: Leukapheresis efficacy is determined by disease subtype and modifiable procedural parameters. Higher processed volume and acute leukemia diagnosis were associated with greater WBC reduction, while CML blast crisis responds poorly. These findings support procedure optimization to maximize cytoreduction.