A comparison of asparaginase activity in generic formulations of E.coli derived L- asparaginase: In-vitro study and retrospective analysis of asparaginase monitoring in pediatric patients with leukemia.

Aims: L-asparaginase is an essential medicine in the treatment of pediatric acute lymphoblastic leukemia (ALL) and the quality of generic formulations is an area of concern. We compared nine generic formulations of L-asparaginase available in India with the innovator.

Methods: The quality of formulations was assessed by measuring 72-hour trough asparaginase activity in children with ALL during induction following administration of 10,000 IU/m of L-asparaginase. In-vitro analysis of the label claim was assessed by measuring activity of three generic formulations. Liquid chromatography-mass spectrometry (LC/MS) was used to determine the amount of host contaminant proteins (HCPs) in the formulations.

Results: Between March 2015 to June 2018, 240 samples from 195 patients were analyzed. The number of samples analyzed ranged from 7-66 per generic brand (median: 18) and seven of the innovator. The proportion of generic formulations that failed to achieve a predefined clinical threshold activity of 50 IU/L ranged from 16.7% (2/12) to 84.9% (28/33) in the highest activity to lowest activity generic respectively. On other hand, all innovator samples had activity greater than 50 IU/L. In-vitro asparaginase activity in the three generic formulations tested ranged from 71.4-74.6% of the label claim (10,000 IU) compared to 93.5% for the innovator. LC/MS analysis of generic 5 identified 25 HCPs with a relative peptide count of 27.1% of the total peptides.

Conclusions: Generic formulations had lower asparaginase activity which raises serious clinical concerns regarding their quality. Until stringent regulatory enforcement improves the quality of these generics, dose adaptive strategies coupled with therapeutic drug monitoring need to be considered.