Glucarpidase

Glucarpidase is a recombinant carboxypeptidase G2 produced by genetically modified Escherichia coli bacteria. It is a 390-amino acid homodimer protein. High-dose methotrexate, an antifolate agent, has been widely and safely used for many decades in treating various cancers; however, even with aggressive hydration, urine alkalinization, and leucovorin rescue, some patients still develop high-dose methotrexate-induced nephrotoxicity. This can lead to delayed renal clearance of methotrexate and elevated drug plasma levels, increasing the risk of methotrexate toxicity.

After the discovery of certain bacteria with the capacity to inactivate folate analogs such as methotrexate, carboxypeptidase G was identified and Carboxypeptidase G1 was first isolated from Pseudomonas stutzeri in 1967. In 1983, the gene for carboxypeptidase G2, or glucarpidase, was derived from Pseudomonas sp. strain RS-16 to be cloned into Escherichia coli, allowing the enzyme to be produced in sufficient quantities for therapeutic purposes. Glucarpidase is an enzyme that can rapidly hydrolyze methotrexate into its nontoxic metabolites. It prevents methotrexate toxicity in patients with renal dysfunction who are undergoing high-dose methotrexate treatment, as it provides an alternative non-renal pathway for methotrexate elimination. Glucarpidase was first approved by the FDA in January 2012, followed by the European Commission's approval in January 2022. It is marketed as VORAXAZE.

Glucarpidase is indicated to reduce toxic plasma methotrexate concentration (greater than 1 micromole per litre) in adult and pediatric patients with delayed methotrexate clearance (plasma methotrexate concentrations greater than 2 standard deviations of the mean methotrexate excretion curve specific for the dose of methotrexate administered) due to impaired renal function. In the European prescribing information, glucarpidase is specified for use in adults and children aged 28 days and older.

Glucarpidase is not recommended for use in patients who exhibit the expected clearance and expected plasma methotrexate concentration. Reducing plasma methotrexate concentration in these patients may result in subtherapeutic exposure to methotrexate.