Asparaginase encapsulated in erythrocytes as second‐line treatment in hypersensitive patients with acute lymphoblastic leukaemia

Summary Asparaginase is essential in treating acute lymphoblastic leukaemia (ALL). Asparaginase‐related hypersensitivity causes treatment discontinuation, which is associated with decreased event‐free survival. To continue asparaginase treatment after hypersensitivity, a formulation of asparaginase encapsulated in erythrocytes (eryaspase) was developed. In NOR‐GRASPALL 2016 (NCT03267030) the safety and efficacy of eryaspase was evaluated in 55 patients (aged 1–45 years; median: 6.1 years) with non‐high‐risk ALL and hypersensitivity to asparaginase conjugated with polyethylene glycol (PEG‐asparaginase). Eryaspase (150 u/kg) was scheduled to complete the intended course of asparaginase (1–7 doses) in two Nordic/Baltic treatment protocols. Forty‐nine (96.1%) patients had asparaginase enzyme activity (AEA) ≥100 iu/l 14 ± 2 days after the first eryaspase infusion [median AEA 511 iu/l; interquartile range (IQR), 291–780], whereas six of nine (66.7%) patients had AEA ≥100 iu/l 14 ± 2 days after the fourth infusion (median AEA 932 iu/l; IQR, 496–163). The mean terminal half‐life of eryaspase following the first infusion was 15.3 ± 15.5 days. Few asparaginase‐related adverse events were reported; five patients (9.1%) developed clinical allergy associated with enzyme inactivation. Replacement therapy was successfully completed in 50 patients (90.9%). Eryaspase was well tolerated, and most patients had AEA levels above the therapeutic target after the first infusion. The half‐life of eryaspase confirmed that a 2‐week schedule is appropriate.