L-Asparagine depletion in plasma and cerebro-spinal fluid of children with acute lymphoblastic leukemia during subsequent exposures to Erwinia L-asparaginase.
BACKGROUND
Monitoring L-asparagine (L-ASN) plasma levels could provide information useful for determining whether the dosage or schedule of L-asparaginase (L-ASE) administration is adequate. Very few data are available on depletion caused by the Erwinia chrysanthemi (E. chrysanthemi) product. Since it has been suggested that L-ASN depletion may have been overestimated in the past due to residual L-ASE activity, samples in this study have been analyzed after deproteinization with sulphosalicylic acid. Patients undergoing subsequent exposures to L-ASE derived from E. chrysanthemi have been investigated.


METHODS
Fifty-four children with newly diagnosed acute lymphoblastic leukemia (ALL) at our institution entered this study. L-ASE was given at conventional doses (10,000 IU/sqm) every three days during the induction phase (8 doses, first exposure) or twice a week (4 doses, second exposure) during the reinduction phase. High-dose L-ASE (i.e., HD-L-ASE 25,000 IU/sqm) was given weekly, for a total of 20 doses, as a second or third exposure during the reinduction and/or maintenance phases. To determine the plasma levels of L-ASN, samples were deproteinized with sulphosalicylic acid, stored at -80 degrees C and then analyzed by HPLC after precolumn derivatization with o-phthaldialdehyde. The CSF samples were analyzed by the same procedure. An experiment was carried out to detect in vitro L-ASE deactivation in patients' plasma.


RESULTS
L-ASN plasma depletion was observed in 80% of the cases during the first exposure to conventional doses of L-ASE and only in 25% of the cases during the second or third exposures to either conventional or high doses of L-ASE. A correlation was found between plasma and CSF L-ASN levels. Activity inhibitory to L-ASE was found in the plasma of patients not depleted during L-ASE treatment and was not found in the plasma of those in whom L-ASN plasma depletion was obtained.


CONCLUSIONS
L-ASN plasma depletion is regularly obtained in the majority of patients during the first exposure to conventional doses of E. chrysanthemi L-ASE. Conversely, in most cases depletion does not occur during subsequent exposures. Studies should be performed to evaluate whether L-ASE derived from different species or conjugated with polyethylene-glycole are effective in obtaining L-ASN plasma depletion in patients previously treated with Erwinia C. L-ASE. The clinical impact of L-ASN depletion should also be investigated in large cohorts of patients.
Gentili
D
D
Department of Pediatrics, University of Milan, Hospital of Monza, Italy.
Conter
V
V
Rizzari
C
C
Tschuemperlin
B
B
Zucchetti
M
M
Orlandoni
D
D
D'Incalci
M
M
Masera
G
G
D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001215:Asparaginase / Q000097:blood / Q000134:cerebrospinal fluid / Q000378:metabolism* / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy / Q000201:enzymology; D011379:Prognosis
D000970:Antineoplastic Agents; D001215:Asparaginase