TY - JOUR
T1 - Methotrexate polyglutamate levels and co-distributions in childhood acute lymphoblastic leukemia maintenance therapy
AU - Nersting, Jacob
AU - Nielsen, Stine Nygaard
AU - Grell, Kathrine
AU - Paerregaard, Maria
AU - Abrahamsson, Jonas
AU - Lund, Bendik
AU - Jonsson, Olafur Gisli
AU - Pruunsild, Kaie
AU - Vaitkeviciene, Goda
AU - Kanerva, Jukka
AU - Schmiegelow, Kjeld
AU - Nordic Society of Paediatric Haematology and Oncology (NOPHO)
PY - 2019/1/31
Y1 - 2019/1/31
N2 - Purpose: Methotrexate polyglutamates (MTXpg) facilitate incorporation of thioguanine nucleotides into DNA (DNA-TG, the primary cytotoxic thiopurine metabolite and outcome determinant in MTX/6-mercaptopurine treatment of childhood ALL). We hypothesized that mapping erythrocyte levels of MTXpg with 1–6 glutamates and their associations with DNA-TG formation would facilitate future guidelines for maintenance therapy dosing. Methods and results: Summed MTX with 1–6 glutamates resolved by LCMS [median (interquartile): 5.47 (3.58–7.69) nmol/mmol hemoglobin] was in agreement with total MTX by radio ligand assay. In 16,389 blood samples from 1426 ALL maintenance therapy patients, MTXpg3 21.0 (15.2–27.4)% was the predominant metabolite, and MTXpg1 (the maternal drug) constituted 38.6 (27.2–50.2)% of MTXpg1–6. All subsets correlated; the strongest associations were between metabolites with similar polyglutamate lengths. Correlations of MTXpg1 with MTXpg2 and MTXpg3,4,5,6 were r s = 0.68 and r s = 0.25–0.42, respectively. Intercorrelations of MTXpg3,4,5,6 were all r s ≥ 0.51. MTXpg4 accounted for 29.8 (24.7–33.3)% of MTXpg3–6, yet explained 96% of the summed MTXpg3–6 variation. MTXpg1–4, MTXpg1–6, MTXpg2–6 and MTXpg3 were all associated with DNA-TG levels (p < 0.00001), but collinearity precluded identification of the most informative subset. Conclusions: Measuring erythrocyte MTXpg4 simplifies and can replace longer chain MTXpg monitoring. Resolving individual MTXpg identifies samples that are unsuitable for dose guidance due to high levels of MTXpg1 remaining in the plasma fraction because of recent MTX intake. All tested MTXpg subsets correlated with DNA-TG and may be used for ALL maintenance therapy dose adjustments, but the most informative subset remains to be identified.
AB - Purpose: Methotrexate polyglutamates (MTXpg) facilitate incorporation of thioguanine nucleotides into DNA (DNA-TG, the primary cytotoxic thiopurine metabolite and outcome determinant in MTX/6-mercaptopurine treatment of childhood ALL). We hypothesized that mapping erythrocyte levels of MTXpg with 1–6 glutamates and their associations with DNA-TG formation would facilitate future guidelines for maintenance therapy dosing. Methods and results: Summed MTX with 1–6 glutamates resolved by LCMS [median (interquartile): 5.47 (3.58–7.69) nmol/mmol hemoglobin] was in agreement with total MTX by radio ligand assay. In 16,389 blood samples from 1426 ALL maintenance therapy patients, MTXpg3 21.0 (15.2–27.4)% was the predominant metabolite, and MTXpg1 (the maternal drug) constituted 38.6 (27.2–50.2)% of MTXpg1–6. All subsets correlated; the strongest associations were between metabolites with similar polyglutamate lengths. Correlations of MTXpg1 with MTXpg2 and MTXpg3,4,5,6 were r s = 0.68 and r s = 0.25–0.42, respectively. Intercorrelations of MTXpg3,4,5,6 were all r s ≥ 0.51. MTXpg4 accounted for 29.8 (24.7–33.3)% of MTXpg3–6, yet explained 96% of the summed MTXpg3–6 variation. MTXpg1–4, MTXpg1–6, MTXpg2–6 and MTXpg3 were all associated with DNA-TG levels (p < 0.00001), but collinearity precluded identification of the most informative subset. Conclusions: Measuring erythrocyte MTXpg4 simplifies and can replace longer chain MTXpg monitoring. Resolving individual MTXpg identifies samples that are unsuitable for dose guidance due to high levels of MTXpg1 remaining in the plasma fraction because of recent MTX intake. All tested MTXpg subsets correlated with DNA-TG and may be used for ALL maintenance therapy dose adjustments, but the most informative subset remains to be identified.
U2 - 10.1007/s00280-018-3704-7
DO - 10.1007/s00280-018-3704-7
M3 - Journal article
C2 - 30324220
SN - 0943-9404
VL - 83
SP - 53
EP - 60
JO - Cancer Chemotherapy and Pharmacology, Supplement
JF - Cancer Chemotherapy and Pharmacology, Supplement
IS - 1
ER -