Effects of L-asparaginase on plasma amino acid profiles and tumor burden in cats with lymphoma.
BACKGROUND
L-Asparaginase (Elspar(a)), is an Escherichia coli-derived enzyme that depletes lymphoma cells of asparagine, inhibiting protein synthesis and resulting in cell death. The single agent response rate in cats with lymphoma and impact of L-asparaginase on plasma amino acid concentrations is unknown.


OBJECTIVE
L-Asparaginase significantly reduces plasma asparagine concentrations and has demonstrable efficacy against untreated lymphoma in cats.


METHODS
Thirteen cats with confirmed lymphoma (LSA) of any anatomic site were given 1 dose 400 IU/kg IM) of L-asparaginase for initial LSA treatment.


METHODS
Plasma collected at 0, 2, and 7 days after L-asparaginase therapy was assayed for ammonia, asparagine, aspartic acid, glutamine, and glutamic acid concentrations. Cats were restaged 7 days later to assess tumor response.


RESULTS
Eight cats had T-cell LSA, 4 cats had B-cell LSA, and 1 cat's immunophenotype was unknown. Two complete and 2 partial responses to L-asparaginase were seen. Four cats had stable disease, and 5 cats had progressive disease. Ammonia and aspartic acid concentrations were increased from baseline at 2 and 7 days posttreatment. Asparagine concentrations were decreased from baseline at 2 days but not 7 days posttreatment. Glutamic acid concentrations were increased at day 2 compared to day 7 posttreatment but not compared to baseline. Glutamine concentrations were unchanged.


CONCLUSIONS
L-asparaginase significantly reduced asparagine concentrations within 2 days of treatment, but this effect was lost within 7 days. The apparent overall response rate of feline LSA to L-asparaginase in this study was 30%.
LeBlanc
A K
AK
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, The University of Tennessee, C247 Veterinary Teaching Hospital, 2407 River Drive, Knoxville, TN 37996-4544, USA. aleblanc@utk.edu
Cox
S K
SK
Kirk
C A
CA
Newman
S J
SJ
Bartges
J W
JW
Legendre
A M
AM
D000596:Amino Acids / Q000097:blood*; D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001215:Asparaginase / Q000627:therapeutic use*; D002371:Cat Diseases / Q000097:blood* / Q000188:drug therapy* / Q000473:pathology; D002415:Cats; D005260:Female; D008223:Lymphoma / Q000097:blood / Q000188:drug therapy / Q000473:pathology / Q000662:veterinary*; D008297:Male
D000596:Amino Acids; D000970:Antineoplastic Agents; D001215:Asparaginase