Simultaneous quantitative detection of afatinib, erlotinib, gefitinib, icotinib, osimertinib and their metabolites in plasma samples of patients with non-small cell lung cancer using liquid chromatography-tandem mass spectrometry

Background and aims: As numerous studies have reported the concentration-exposure relationships of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), therapeutic drug monitoring is a promising approach in lung cancer treatment, aiming to avoid treatment failure or toxicity. A new method for the simultaneous analysis of five EGFR-TKIs (afatinib, erlotinib, gefitinib, icotinib and osimertinib) and their metabolites in human plasma samples was developed and validated using liquid chromatography-tandem mass spectrometry (LC-MS/MS).& nbsp;Materials and methods: Afatinib-d(6), erlotinib-d(6), OSI-420-d(4), gefitinib-d(6) and osimertinib-C13,d3 were used as internal standards (ISs). The samples were prepared by liquid-liquid extraction using tert-butyl methyl ether. Chromatographic separation was undertaken on an XBridge C-18 column using a linear gradient elution. LC-MS/ MS was conducted in positive ionization mode with multiple reaction monitoring.& nbsp;Results: The proposed method showed satisfactory results in terms of linearity, sensitivity, specificity, precision (intra-and inter-day coefficients of variation ranged from 1.1 to 13.9%), and accuracy (from 93.3 to 111.1%). The IS-normalized matrix factors were below 15%. The sensitivity and linearity were highly appropriate for the expected concentrations according to the analysis of samples from non-small cell lung caner (NSCLC) patients who received EGFR-TKIs.& nbsp;Conclusions: The proposed method showed an acceptable reproducibility, high sensitivity and selectivity, and low matrix effects. This method could be significant for monitoring plasma concentrations of the mentioned EGFRTKIs in NSCLC patients, aiming to improve the efficacy and safety of targeted therapies.