9015-68-3

Antineoplastic.

Crasnitin (Bayer); Elspar (Merck).

Enzon (U.S.A.)

The enzyme L-asparaginase (Elspar) is derived from the bacteria Escherichia coli and Erwinia carotovora. It catalyzes the hydrolysis of L-asparagine to aspartic acid and ammonia. L-Glutamine also can undergo hydrolysis by this enzyme, and during therapy, the plasma levels of both amino acid substrates fall to zero.Tumor cells sensitive to L-asparaginase are deficient in the enzyme asparagine synthetase and therefore cannot synthesize asparagine. Depletion of exogenous asparagine and glutamine inhibits protein synthesis in cells lacking asparagine synthetase, which leads to inhibition of nucleic acid synthesis and cell death.

Therapeutically active L-asparaginase is isolated from bacteria from the genus Erwinia, a known genus pathogenic towards plants. L-asparaginase is conveniently isolated from this genus by growing the bacteria upon a suitable nutrient medium until a desired quantity is obtained and then extracting the L-asparaginase either by conventional cell disruption methods, or preferably, by processes more fully described in US Patent 3,660,238.

Antineoplastic (acute leukemia)

Asparaginase is available in 10-mL vials for intramuscularand IV use in the treatment of acute lymphocytic leukemia.
Tumor cells are unable to synthesize asparagine, and thereforemust utilize what is available in the extracellular environment.The agent acts by hydrolyzing extracellular asparagineto aspartate and ammonia. The tumor cells are then deprivedof a necessary nutrient, and protein synthesis is inhibited leadingto cell death. The agent is specific for the G₁ phase of thecell cycle. Resistance occurs because of the development ofthe tumor cells ability to produce asparagine synthetase thatallows them to synthesize the required amino acid. Antibodyproduction directed at asparaginase may be stimulated by theagent as well. The agent remains in the extracellular spaceafter parental administration and is 30% protein bound. Themetabolism of the agent has not been well characterized andthe plasma half-life depends on the formulation of the drug.The E. coli-derived agent has a plasma half-life of 40 to 50hours, whereas polyethylene glycol-asparaginase’s half-life is3 to 5 days. Adverse effects include hypersensitivity reactions,fever, chills, nausea, lethargy, confusion, hallucinations,and possibly coma. Myelosuppression is not generallyseen. An increased risk of bleeding and clotting is seen in halfof the patients taking the agent.

Asparaginase (ASNase) products are usually obtained from?Escherichia coli?and?Erwinia chrysanthemi. These enzymes can block the synthesis of protein in tumor cells. It shows high activity in the G1?phase of the cell cycle. It is capable of causing pancreatitis in leukemia patients.

L-asparaginase (EC. 3.5.1.1; asparagine amidohydrolase) catalyzes the hydrolysis of L-Asparagine to L-aspartic acid and ammonia. This enzyme is used for the treatment of selected types of hemopoietic diseases such as acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphomas (Pieters et al. 2011; Rytting 2012). It is also a model enzyme for the development of new drug delivery system and L-asparagine biosensor for leukemia. This enzyme was used in the food industry for the production of acrylamide free food (Kumar and Verma 2012; Dhanam Jayam and Kannan 2013).
Y. lipolytica is a potential producer of L-asparaginase. However, there are very few reports on L-asparaginase production by the yeast. Karanam and Medicherla optimized L-asparaginase production of Y. lipolytica NCIM 3472 in solid-state fermentation (SSF) using palm kernel cake as the substrate. The maximum L-asparaginase activity at optimum conditions was near 40 U/g of the initial dry substrate (U/gds) (Karanam and Medicherla 2010).

The half-life of L-asparaginase in human plasma is 6 to 30 hours.The drug remains primarily in the intravascular space, so its volume of distribution is only slightly greater than that of the plasma. Metabolism and disposition are thought to occur through serum proteases, the reticuloendothelial system, and especially in patients with prior exposure to the drug, binding by antibodies. The drug is not excreted in urine, and very little appears in the CSF.

Both the commonly known and distinctive species have been reported to produceL-asparaginase. The common species of endophytes, which produce L-asparaginase,include Fusarium sp., Penicillium sp., and Colletotrichum sp. They are isolated asendophytes from a variety of medicinal plants (Audipudi et al. 2014; El-Said et al.2016).
Chow and Ting (2015) studiedL-asparaginase production from fungal endophytes isolated from anticancer plantsin Malaysia. They found Fusarium oxysporum and Penicillium simplicissimumfrom Murraya koenigii and Pereskia bleo, respectively, as effective producers ofL-asparaginase. In addition to L-asparaginase, endophytes from anticancer plantshave also been established as producers of other valuable anticancer, antimicrobial,and antioxidant compounds. This is further supported by many reports on discoveryof these anticancer agents in different species of endophytic fungi either from sameor different host plants.

Pegaspargase, a polyethylene glycol conjugate of L-asparaglnase (ASNase), was launched for combination chemotherapy in acute lymphoblastic leukemia (ALL). L-Asparaginase is an enzyme that inhibits protein synthesis by the depletion of sources of L-asparagine, which is necessary for transformed lymphoid cells to proliferate. It has been used as a standard component of the antileukemia armamentarium for childhood All. Pegaspargase has greater antitumor activity, a longer plasma half-life and less immunogenicity than ASNase. It produces minimal side effects after repeated dosing, whereas ASNase induces anaphylactic shock, urticaria, anorexia or vomiting and acute pancreatitis in dogs, and other immunological effects in man resulting from sensitization to the enzyme or protein synthesis inhibition. The efficacy of pegaspargase for other indications including breast and lung cancers, non-Hodgkin's lymphoma and pancreatic cancer has been reported.

The major indication for L-asparaginase is in the treatment of acute lymphoblastic leukemia; complete remission rates of 50 to 60% are possible. Lack of crossresistance and bone marrow toxicity make the enzyme particularly useful in combination chemotherapy. LAsparaginase also can be used in the treatment of certain types of lymphoma. It has no role in the treatment of nonlymphocytic leukemias or other types of cancer.

Since it is a foreign protein, L-asparaginase may produce hypersensitivity reactions, including urticarial skin rashes and severe anaphylactic reactions. One-third of patients have nausea, anorexia, weight loss, and mild fever. Almost all patients develop elevated serum transaminases and other biochemical indices of hepatic dysfunction. Severe hepatic toxicity occurs in fewer than 5% of cases. Patients receiving L-asparaginase may develop symptoms of CNS toxicity, including drowsiness, confusion, impaired mentation, and even coma. Pancreatitis occurs in 5 to 10% of cases.Hyperglycemia, possibly due to inhibition of insulin synthesis, also may occur. L-Asparaginase differs from most cytotoxic drugs in its lack of toxicity to bone marrow, gastrointestinal tract, and hair follicles.

Human (child) systemic effects byintramuscular route. An experimental teratogen. Otherexperimental reproductive effects. Questionablecarcinogen with experimental neoplastigenic data.

Asparaginase has been useful in combination with other agents in the treatment of lymphoid malignancies. The drug is most useful in inducing remission of disease but is occasionally used in maintenance or rescue protocols.
Use of asparaginase as part of an initial treatment lymphosarcoma protocol is now somewhat controversial, as one study (MacDonald, Thamm et al. 2005) in dogs showed no statistical difference for response rates, remission or survival rate, remission or survival duration, or prevalence of toxicity and treatment delay in dogs treated with or without asparaginase as part of a standard CHOP protocol.