A highly sensitive method for the detection of PKC412 (CGP41251) and its metabolites by high-performance liquid chromatography.

Introduction: PKC412 has proven activity in the treatment of acute myelogenous leukemia (AML). The drug is extensively metabolized, and recently it was shown that its metabolites have differing efficacies against malignant cells. Therefore, we established a new isocratic HPLC method, which sensitively detects PKC412 and five of its metabolites.

Method: Quantification was performed using N-phenyl-1-naphtylamine as an internal standard. We could demonstrate linearity in a range from 10 to 10,000 ng/ml PKC412 with an intra-day variability of less than 7.5% and an inter-day-variability of less than 11%.

Results: The assay was used to monitor plasma samples from patients with AML treated within a clinical trial. Here we could demonstrate the ability of the assay to detect five metabolites of PKC412 and describe the application of the assay for drug monitoring in clinical situations.

Conclusion: The assay described here will enable a discriminative analysis of PKC412 and its metabolites in human plasma samples. First clinical application of the assay suggests different rates of metabolism of the individual metabolites of PKC412 with e.g. accumulation of CGP52421 epimer 2 even after cessation of therapy. Since it is assumed that different metabolites of PKC412 have a very individual mode of actions, determination of PKC412 and its metabolites within clinical studies of the drug will be important.