PB0741 - Plasma podoplanin is increased in newly diagnosed acute promyelocytic leukemia compared to other types of acute myeloid leukemia and associates with platelet activation

Background: The coagulopathy of acute promyelocytic leukemia (APL) is responsible for an extremely high rate of severe bleeding and early death in a group patients that present an otherwise better long term prognosis compared to other forms of types acute myeloid leukemia (AML). Recently, the expression of podoplanin (PDPN), a protein that mediates platelet activation in inflammatory contexts, by leukemic cells was described as relevant to this coagulopathy.

Aims: To explore whether circulating levels of PDPN can be used as a biomarker of APL, and whether its levels are associated with clinical or laboratory markers of platelet and coagulation activation in APL

Methods: Samples were obtained from consecutive patients with APL at the time of diagnosis in an academic hospital. Biobank samples from 35 patients with non-APL AML matched for age and sex were used in comparative analyses. Clinical and laboratory data were extracted from the medical records. Circulating PDPN levels were measured in plasma (EDTA) using a commercial Elisa kit. Biomarkers of platelet and coagulation activation were measured using multiplex immunological assays. The study was approved by the IRB and all participants provided written informed consent.

Results: Clinical and laboratory data from the study population are shown in table 1. PDPN levels were significantly higher in APL compared to other forms of AML (figure 1A). Among tested parameters, PDPN correlated with a classical biomarker of platelet (CD40L) among APL patients (figure 1B). However, PDPN levels were not associated with the development of bleeding or thrombosis among APL patients from this cohort.

Conclusion(s): Circulating PDPN levels are higher in APL, and correlate with laboratory evidence of platelet activation. Additional studies are warranted to confirm these findings and to further explore the association of PDPN with the clinical presentation of APL coagulopathy.