Successful treatment of relapsed infant acute lymphoblastic leukemia with intensive antimetabolite-based chemotherapy

Polyethylene Glycol-conjugated L-asparaginase versus native L-asparaginase in combination with standard agents for children with acute lymphoblastic leukemia in second bone marrow relapse: a Children's Oncology Group Study (POG 8866)

BACKGROUND

Administration of L-asparaginase is limited by hypersensitivity reactions mediated by anti-asparaginase antibodies. To overcome this problem, native Escherichia coli L-asparaginase was conjugated to polyethylene glycol (PEG) to formulate PEG-L-asparaginase, a preparation with decreased immunogenicity and increased circulating half-life. In early trials, PEG-L-asparaginase was tolerated by patients known to be hypersensitive to the native E. coli product.

METHODS

The Pediatric Oncology Group conducted a phase II, randomized trial to compare the efficacy and toxicity of PEG-L-asparaginase compared with native E. coli asparaginase in children with acute lymphoblastic leukemia in second bone marrow relapse. All patients (n=76) received standard doses of vincristine and prednisone. Nonhypersensitive patients (n=34) were randomized to receive either PEG-L-asparaginase of 2500 IU/m/dose intramuscularly on days 1 and 15 (treatment I) or native E. coli asparaginase of 10,000 IU/m/dose intramuscularly on days 1, 3, 5, 8, 10, 12, 15, 17, 19, 22, 24, and 26 (treatment II). Patients with a clinical history of an allergic reaction to unmodified asparaginase were directly assigned to treatment with PEG-L-asparaginase (n=42). Asparaginase levels and anti-asparaginase antibody titers were monitored in all patients. Response and toxicity were scored using conventional criteria.

RESULTS

The complete response rate for the total study population was 41%. There was no difference in complete response between patients randomized to PEG (47%) and native asparaginase (41%). PEG was well tolerated even in patients with prior allergic reactions to native asparaginase. PEG half-life was shorter in patients with prior allergy.

CONCLUSIONS

PEG asparaginase is a useful agent in patients with allergic reactions to native asparaginase.

Congenital and neonatal leukemia

Congenital and neonatal leukemia occur rarely, yet carry high mortality rates and pose special problems for the perinatologist and hematologist. Although the etiology is unknown, the presence of leukemia at birth suggests genetic abnormalities and possibly intrauterine exposures to drugs or other toxins as contributing factors. Specific chromosomal rearrangements that are common in congenital leukemia have recently been identified and promise to enhance our understanding of these enigmatic diseases. The differential diagnosis is broad and includes many disorders that occur frequently in the neonatal period. Infants diagnosed with congenital or neonatal leukemia require thorough investigative workup and extensive supportive care. Although the prognosis is poor, recent use of high-intensity multiagent chemotherapy regimens has produced promising results.