A previous European phase I/II clinical study in children and adults (<55 yo) at first relapse of ALL was conducted to determine the optimal dose of homologous RBC encapsulating native E. coli Asp (GRASPA®) in 24 patients with relapsed ALL. The activity and safety profiles of 3 doses of GRASPA® (50, 100 and 150 IU/kg) in combination with standard chemotherapy were compared to free native Asp. The global safety profile is also improved, reducing hypersensitivity, liver toxicity and coagulation disorders. Study showed that a single dose of GRASPA® 150 IU/kg induced a depletion in plasmatic asparagine for 18.6 days, i.e. similar to that obtained with 8 injections of 10,000 IU/m² of free native Asp. A reduction in the incidence and severity of the allergic reactions and coagulation disorders were observed with GRASPA® (Domenech 2011).