L-Asparaginase Loaded Red Blood Cells: From Prescription to Injection

Abstract 4252

L-asparaginase has been a mainstay of acute lymphoblastic leukemia (ALL) treatment since decades and its efficacy has been demonstrated in a broad range of patient's profiles. However its use is hampered by frequent and/or significant toxicities.

L-asparaginase loaded in homologous red blood cells (GRASPA®) is a new pharmaceutical formulation of the enzyme. This cell-based medicinal product allows a better safety profile and an improvement of the pharmacokinetics and pharmacodynamics of the enzyme. As demonstrated by several teams performing different technologies of entrapment (Alpar-HO, 1985; Updike-SJ, 1985; Naqi-A 1988; Kravtzoff-R, 1996; Kwon-YM, 2010; Domenech-C, 2010), L-asparaginase remains active entrapped inside the red blood cell (RBC), while asparagine is constently and actively “pumped” through the membrane of the red cells thanks to N+ channel system. Thus, L-asparaginase loaded RBCs act as “cellular bioreactors”. Indeed, plasmatic asparagine diffuses through the RBC membrane to the intra cellular compartment where it is cleaved by the entrapped L-asparaginase. Thanks to the RBC membrane, the enzyme is protected from body reaction thus reducing the side effects.

L-asparaginase loaded red blood cells is a cell-based medicinal product for personalized medicine. The physician prescribes the drug, then the hospital orders the product to the company. The patient weight, the ABO blood type and a valid irregular antibody screening (IAS) have to be joined with this order. The qualified person on the manufacturing site, orders immediately to a blood bank a leukocytes reduced packed RBC unit compatible with the patient. The product is manufactured under cGMP using a 3-hours automated process: (1) a washing step removes the preservative solution from the packed RBC, (2) L-asparaginase is mixed to the RBC washed suspension, (3) the mixture is dialyzed against a hypotonic solution and resealed, (4) a final washing step allows to purify the product, finally (5) the preservative solution is added. According to the prescribed dosage (IU/Kg), the volume of GRASPA® is adjusted in the final product PVC bag. Indeed, the product release specifications are constant and reproducible from batch to batch such as the corpuscular concentration of L-asparaginase (117±19, IU/ml), extracellular hemoglobin (0.11±0.03 g/dL), osmotic fragility (<3.5 g/L of NaCl), extracellular L-asparaginase (0.4±0.2 IU/ml ie <1% of the total activity). Based on these specifications, the qualified person releases the product and ships it (kept at 2–8°C) to the prescriber, meaning the delay between order and delivery is less than 2 days. Currently a 72h shelf-life for the final product is considered. The traceability system assures the linkage between the blood bank and patient's hospital.

The manufacturing Key Peformance Indicators:

To date, 135 batches of GRAPSA® were administered to 71 patients enrolled in 3 clinical trials. In ALL patients, hypersensitive reaction, coagulation disorders, hepatic disorders are significantly reduced. The dose of 150IU/kg is currently used in a phase II/III pivotal trial in children and adults with ALL relapse. The dose of 100 IU/kg is optimal (efficacy/tolerance) in newly diagnosed patients over 55yo. Indeed this frail subpopulation of patients can difficultly receive current forms of L-asparaginase due to the known side effects. A phase I clinical trial in pancreatic carcinoma confirmed the good safety profile (also at 150IU/kg) of this form of L-asparaginase even in solid tumors, offering new perspectives in patients where asparagine synthetase in tumor cells is down.