培门冬酶 (Oncaspar)

概览

Pegaspargase is a modified form of L-asparagine amidohydrolase used to treat acute lymphoblastic leukemia, which is dependent on an external source of asparagine.

作用机制

Pegaspargase is a pegylated L-asparaginase that catalyzes the conversion of the amino acid L-asparagine into aspartic acid and ammonia. Asparagine is an amino acid that is vital for DNA and RNA synthesis and cell division. It is not an essential amino acid in humans since most normal human tissues can produce asparagine via the enzyme asparagine synthetase. However, leukemia cells have low levels of this enzyme and are unable to synthesize asparagine, making them dependent on exogenous sources. It has been suggested that pegaspargase kills leukemic cells by depleting plasma asparagine. Both Escherichia coli-derived L-asparaginase and pegaspargase follow the same mechanism of action; however, Escherichia coli-derived L-asparaginase requires frequent administration, presents a high incidence of hypersensitivity reactions, and can be neutralized without any signs of hypersensitivity. By pegylating L-asparaginase, the circulation time of L-asparaginase can be extended, and immunogenicity is reduced.

适应症

Pegaspargase is indicated as a component of a multi-agent chemotherapeutic regimen for the treatment of pediatric and adult patients with 1) first-line acute lymphoblastic leukemia or 2) acute lymphoblastic leukemia and hypersensitivity to asparaginase.

• Acute Lymphoblastic Leukaemias (ALL)