High-dose methotrexate is a cornerstone agent in the chemotherapeutic treatment of patients with osteosarcoma. However, patients often develop methotrexate-induced toxicities. We aim to identify... Show moreHigh-dose methotrexate is a cornerstone agent in the chemotherapeutic treatment of patients with osteosarcoma. However, patients often develop methotrexate-induced toxicities. We aim to identify determinants of methotrexate-induced toxicities in osteosarcoma patients by investigating the relation between drug plasma levels, methotrexate-induced toxicities, and germline variants in genes related to drug absorption, distribution, metabolism, and elimination. A cohort of 114 osteosarcoma patients was genotyped for 1,931 variants in 231 genes using the Drug Metabolism Enzymes and Transporters Plus array. Methotrexate plasma levels and laboratory measurements during and after high-dose methotrexate treatment concerning renal function, liver damage, and myelopoiesis to reflect toxicity outcomes were obtained. One hundred and thirteen patients and a subset of 545 variants in 176 genes passed quality control checks. Methotrexate plasma levels showed associations with creatinine, alanine aminotransferase, and hemoglobin. Genetic variant rs3736599 in the 5'-untranslated region ofSULT1E1 was associated with lower 48 hour methotrexate plasma levels [coef -0.313 (95% CI -0.459 - -0.167); p = 2.60 x 10(-5)]. Association with methotrexate-induced decreased thrombocyte counts was found for two intronic variants in CYP2B6{rs4803418 [coef -0.187 (95% CI -0.275 - -0.099); p = 3.04 x 10(-5)] and rs4803419 [coef -0.186 (95% CI -0.278 - -0.093); p = 8.80 x 10(-5)]}. An association with increased thrombocyte counts was identified for the intronic variant rs4808326 in CYP4F8 [coef 0.193 (95% CI 0.099 - 0.287); p = 6.02 x 10(-5)]. Moreover, a secondary analysis with a binary approach using CTCAE toxicity criteria resulted in a nominal significant associations (p < 0.05) for two out of three variants (rs4803418 and rs4808326). This is the first study to identify genetic variants inSULT1E1, CYP2B6, andCYP4F8to be associated with methotrexate pharmacokinetics and toxicities. Validation of these variants in an independent cohort and further functional investigation of variants in the identified genes is needed to determine if and how they affect methotrexate plasma levels and the development of methotrexate-induced toxicities. Show less
Gan, J.; Leestemaker, Y.; Sapmaz, A.; Ovaa, H. 2019
Background: As part of an integrated and innovative approach to accelerate the clinical development of the dual receptor antagonist ACT-541468, 6 healthy subjects in one cohort in a first-in-humans... Show moreBackground: As part of an integrated and innovative approach to accelerate the clinical development of the dual receptor antagonist ACT-541468, 6 healthy subjects in one cohort in a first-in-humans (FIH) study received an oral dose of 50 mg non-labeled ACT-541468 together with a microtracer amount of 250 nCi of C-14-labeled ACT-541468 to investigate its absorption, distribution, metabolism, and excretion (ADME).Methods: Using accelerator mass spectrometry (AMS), radiochromatograms were constructed for fractionated plasma, urine, and feces samples. Subsequently, the structures of the metabolites were elucidated using high performance liquid chromatography (HPLC) coupled with high resolution mass spectrometry.Results: In total 77 metabolites have been identified of which 30, 28, and 60 were present in plasma, urine, and feces, respectively. In plasma, the major metabolites were the mono-oxidized benzylic alcohol M3, the ACT-541468 aldehyde M1, formed by further oxidation of M3 in the benzylic position, and the doubly oxidized M10, formed by (1) benzylic oxidation of M3 (loss of one molecule of water and one molecule of ammonia) and (2) additional loss of water from the oxidized pyrrolidine ring of M5. Transformation of the pyrrolidine to a 6-membered ring was detected. Metabolites that accounted for more than 5% of total radioactivity in excreta were M2, which is also formed by oxidation at the benzylic position, M4, formed by demethylation of the methoxy-group, M7 and A6, both formed by oxidation of M4, and M10, the only major metabolite detected in urine.Conclusion: In conclusion, ACT-541468 is extensively metabolized predominantly by oxidative transformations. Show less
Vihinen, M.; Dunnen, J.T. den; Dalgleish, R.; Cotton, R.G.H. 2012
