Asparaginase-related venous thrombosis in UKALL 2003- re-exposure to asparaginase is feasible and safe.

We report the incidence and outcome of venous thrombosis (VT) in the UK acute lymphoblastic leukaemia (ALL) 2003 trial. VT occurred in 59/1824 (3.2%) patients recruited over 5 years with 90% occurring during a period of Asparagine depletion. Pegylated Escherichia Coli Asparaginase (Peg-ASP) 1000 units/m(2) was used throughout. Thirty-four children received further Peg-ASP, most with concurrent heparin prophylaxis. There were no episodes of bleeding or recurrent thrombosis. Optimal Asparagine depletion is central to success of modern regimes for treatment of ALL. This report confirms a significant risk of thrombosis with such therapy, but demonstrates that re-exposure to Asparaginase is feasible and safe.