1. 2,4-Diamino-N10-methylpteroic acid (DAMPA) crystalluria in a patient with osteosarcoma treated with carboxypeptidase-G2 rescue after high-dose methotrexate-induced nephrotoxicity.
- Author
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Berga, Francisco, Luna, Pablo, Martorell, Clara, Rey, Juan, Gomila, Isabel, Gimenez, Sandra, Costa-Bauza, Antonia, Elorza, Miguel Ángel, Sánchez, Iolanda, Grases, Félix, and Barceló, Bernardino
- Subjects
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OSTEOSARCOMA , *NEPHROTOXICOLOGY , *CANCER chemotherapy , *GLUTAMIC acid , *SCANNING electron microscopy - Abstract
Abstract Background High-dose methotrexate (HDMTX) therapy is a key component of many chemotherapy protocols. However, some patients develop HDMTX-induced nephrotoxicity. Carboxypeptidase-G2 (CPDG2) hydrolyses MTX into 2,4-diamino-N10-methylpteroic acid (DAMPA) and glutamic acid, and is used as a rescue agent in patients with nephrotoxicity and delayed elimination. Despite the frequency of HDMTX-induced renal injury, crystalluria is uncommon. Furthermore, crystals are rarely identified by conventional chemical methods. Objective To determine the composition of crystalluria in a patient with osteosarcoma who was treated with CPDG2. Methods Crystalluria was evaluated by optical microscopy, and chemical identification was performed by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and Orbitrap™ high-resolution mass spectrometry (HRMS). Results The HRMS spectra of the patient's urine sediment showed a main peak at m / z 326.13, corresponding to the molecular mass of DAMPA [(C 15 H 15 O 2 N 7) + H+]. The FT-IR spectral patterns of the sediment and DAMPA were not identical. SEM was unable to identify the crystal. Conclusion DAMPA crystalluria was identified by Orbitrap™ HRMS in a patient treated with CPDG2 after HDMTX nephrotoxicity. This case reinforces the need to implement adequate measures to prevent nephrotoxicity. In cases of HDMTX-induced nephrotoxicity, urine sediment analysis should be requested. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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