Lysyl Oxidase Expression is Associated with Inferior Outcome and Extramedullary Disease of Acute Myeloid Leukemia

Background: Lysyl oxidase (LOX) has been described as necessary for premetastatic niche formation in epithelium-derived malignancies and its expression level therefore correlates with risk of metastatic disease and overall survival. However, its role in acute myeloid leukemia (AML) has not been sufficiently analyzed.

Methods: We investigated LOX plasma expression in 683 AML patients (age 17-60 years) treated within the prospective AML2003 trial (NCT00180102). The optimal cut-off LOX value was determined using a minimal--value method dichotomizing patients into a LOX-high group (> 109 ng/mL,  = 272, 40%) and a LOX-low group (≤ 109 ng/mL,  = 411, 60%).

Results: Higher LOX expression was associated with lower peripheral white blood cells, lower serum LDH, and a lower frequency of -ITD and mutations at diagnosis. Higher LOX expression was found significantly more frequently in patients with secondary AML and therapy-related AML, in patients with French-American-British M5 subtypes, and in patients with adverse-risk cytogenetics. Comparing patients in the LOX-high group and the LOX-low group revealed a 3-year overall survival (OS) of 47 and 53% ( = 0.022) and 3-year event-free survival (EFS) of 27 and 35% ( = 0.005), respectively. In the LOX-high group significantly more patients had extramedullary AML compared to the LOX-low group ( = 0.037). Combining extramedullary AML and LOX as interacting factors in a multivariate analysis resulted in an independent impact on survival for the LOX-high-extramedullary interaction for OS (HR = 2.25,  = 0.025) and EFS (HR = 2.48,  = 0.008). Furthermore, in patients with extramedullary disease ( = 59) the LOX level predicted survival. Patients within the LOX-low group had an OS of 43% and EFS of 36% as compared to the LOX-high group with an OS of 13% and EFS of 6% ( = 0.002 and  = 0.008, respectively).

Conclusion: We hypothesize LOX expression to be a new potential biomarker to predict outcome in AML, specifically in AML subgroups such as the prognostic heterogeneous group of AML patients with extramedullary disease.

Trial Registration: This retrospective study was performed with patient samples registered within the prospective AML2003 trial (NCT00180102). Patients were enrolled between December 2003 and November 2009.