Marked elevation in homocysteine and homocysteine sulfinic acid in the cerebrospinal fluid of lymphoma patients receiving intensive treatment with methotrexate.
OBJECTIVE
Interference of methotrexate (MTX) with the metabolism of homocysteine may contribute to MTX neurotoxicity. In this pilot study we measured the concentration of homocysteine and related metabolites in the cerebrospinal fluid (CSF) of patients with primary central nervous system lymphoma undergoing intensive treatment with MTX.


METHODS
CSF samples from lymphoma patients (n = 4) were drawn at the end of high-dose MTX infusions (3-5 g/m2/24 h, HDMTX) and one day after intraventricular injections of MTX (3 mg, ICVMTX) or cytarabine (30 mg) and analyzed for homocysteine, cysteine, sulfur-containing excitatory amino acids (cysteine sulfinic acid, cysteic acid, homocysteine sulfinic acid and homocysteic acid), S-adenosylmethionine, 5-methyltetrahydrofolate and MTX. The concentration of homocysteine, cysteine and sulfur-containing excitatory amino acids were also measured in the CSF of a reference population not exposed to MTX. The Wilcoxon signed rank-test and the Friedman test were used to compare concentrations of homocysteine and its metabolites at various time-points during chemotherapy. Comparison of patient and control samples were performed using the Mann-Whitney U-test. Allelic variants of homocysteine metabolism previously shown to influence MTX neurotoxicity (MTHFR c.677C>T, MS c.2756A>G and Tc2 c.776C>G) were also analyzed.


RESULTS
After application of HD- and ICVMTX, the CSF homocysteine concentrations in the lymphoma patients were markedly elevated and significantly higher than those in the control group (p < 0.05, Mann-Whitney U-test), whereas 5-methyltetrahydrofolate was depleted. A rapid elevation of homocysteine sulfinic acid, a sulfur-containg amino acid which was not detected in the CSF of the control group, was observed. One patient developed confluent white matter brain changes visible using MRI. This patient had the lowest concentration of S-adenosylmethionine in the CSF and carried two risk alleles for MTX neurotoxicity.


CONCLUSIONS
In this pilot study, MTX administered either intravenously or intraventricularly, induced marked biochemical alterations in the CSF. Whether these changes can be used to predict MTX-induced neurotoxicity at an early stage in treatment needs to be elucidated in larger clinical trials.
Becker
A
A
Department of Clinical Pharmacy, Institute of Pharmacy, University of Bonn, Germany.
Vezmar
S
S
Linnebank
M
M
Pels
H
H
Bode
U
U
Schlegel
U
U
Jaehde
U
U
D000328:Adult; D000368:Aged; D000483:Alleles; D000964:Antimetabolites, Antineoplastic / Q000009:adverse effects / Q000494:pharmacology*; D001923:Brain Chemistry / Q000187:drug effects; D016543:Central Nervous System Neoplasms / Q000188:drug therapy; D003561:Cytarabine; D018846:Excitatory Amino Acids / Q000134:cerebrospinal fluid; D005260:Female; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000134:cerebrospinal fluid*; D006801:Humans; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008223:Lymphoma / Q000188:drug therapy*; D008297:Male; D008727:Methotrexate / Q000009:adverse effects / Q000494:pharmacology*; D008875:Middle Aged; D020258:Neurotoxicity Syndromes; D010865:Pilot Projects; D012436:S-Adenosylmethionine / Q000134:cerebrospinal fluid; D018709:Statistics, Nonparametric; D013997:Time Factors
D000964:Antimetabolites, Antineoplastic; D018846:Excitatory Amino Acids; D003561:Cytarabine; D006710:Homocysteine; C010982:homocysteinesulfinic acid; D012436:S-Adenosylmethionine; D008727:Methotrexate