Determination of the glucuronide metabolite of ON 013100, a benzylstyrylsulfone antineoplastic drug, in colon cancer cells using LC/MS/MS

ON 013100, (E)-2,4,6-trimethoxystyryl-3-hydroxy-4-methoxybenzyl sulfone, is a potent kinase inhibitor whose phosphate form is in Phase I clinical trials in lymphoma and acute lymphoid leukemia. The objectives were to: (a) investigate the possible presence of the glucuronide metabolite of the drug in two representative colon cancer cell lines, a drug resistant (colo-205) and a drug sensitive (colo-320); (b) quantify the glucuronide metabolite and the unchanged drug in the cells after treatment with ON 013100. The glucuronide was synthesized and a selective LC/MS/MS method was developed and validated for the characterization and quantification of the metabolite. The glucuronide metabolite (570.6. Da) was found in the drug-resistant cells upon a 1. h incubation with ON 013100 (20 μg/ml). After treatment with the drug, the concentration of the metabolite gradually decreased from 0.84 μg/ml at 0. h through 0.21 μg/ml at 6. h to below detection limit of 8.0. ng/ml at 9. h. No glucuronide metabolite was detected in the drug-sensitive cells. The concentrations of intact ON 013100 in the drug-resistant cells gradually decreased from 0.41 μg/ml (0. h) to 0.06 μg/ml (9. h). The corresponding concentrations of the intact drug in the drug-sensitive cells were from 2.88 μg/ml to 0.94 μg/ml.