[Clinical application of the simultaneous detection of methotrexate and 7-hydroxymethotrexate in the delayed...

Objective: To discuss the application value of the simultaneous determination of methotrexate (MTX) and 7-hydroxymethotrexate (7-OHMTX) in the delayed elimination of MTX for pediatric acute lymphoblastic leukemia (ALL). Methods: Cross sectional study. A total of 97 children who received 192 high-dose MTX treatments cycles in Lu Daopei Hospital from April to August 2019 were enrolled. The peripheral blood was collected at 0,24,48 h after the end of MTX infusion and analyzed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). One hundred and ninety-two MTX treatments were divided into a normal MTX elimination group (n=149) and delayed elimination group (n=43) according to the standard of delayed elimination and divided into 0-9 year old group (n=95), 10-14 group (n=50), 15-18 group (n=47) according to age. The comparisons of the C(MTX), C(7-OHMTX) between normal and delayed group was conducted as well as among different age groups. Receiver operator characteristic curve (ROC) of C(MTX-0h) and C(7-OHMTX-0h) was analyzed and the concentration corresponding to the maximum of the Youden index on the ROC was set as the warning value for delayed elimination. Correlation between the delayed elimination after the end of MTX infusion and toxicity was investigated and the percentage of delayed elimination was also analyzed. Results: The concentrations of MTX and 7-OHMTX were significantly higher in the delayed elimination group than the normal group. Immediately after infusion (0 h), a C(7-OHMTX-0h) of >17.8 μmol/L (sensitivity 97.7%, specificity 54.4%) and a C(MTX-0h) of >148.8 μmol/L (sensitivity 72.1%, specificity 84.6%) were found to be warning predictors of delayed elimination under the MTX treatment protocol. MTX delayed elimination was positively correlated with methotrexate-induced toxicities (r=0.58, P<0.01). The percentage of hepatotoxicity and nephrotoxicity was 32.6% and 37.2% in the delayed elimination group, which was significantly higher than normal group of 12.8% and 3.4% (P<0.05). No significant difference was found in other toxicities. There was significant difference in C(MTX) among different age groups but no significant difference in C(7-OHMTX). Conclusion: Simultaneously determination of MTX and 7-OHMTX in plasma by HPLC-MS/MS in childhood ALL patients can provide a reference for clinical individualized medicine and pharmacokinetic research.