A rapid and sensitive ultra‐performance liquid chromatography tandem mass spectrometry method for determination of anlotinib in plasma and dried blood spots: Method development, validation, and clinical application

RATIONALE: Anlotinib is a multi-target tyrosine kinase inhibitor, approved in China for treating several cancer types. Dose individualization based on therapeutic drug monitoring (TDM) is a useful tool to reduce toxicity. However, it is not convenient for patients to go to hospital for routine TDM via venous blood sampling at a certain time. METHODS: An ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for determination of anlotinib in human plasma and dried blood spot (DBS), characterized by simple sample preparation, high sensitivity, and short analysis time. The assay was validated in the concentration range of 0.2-200 ng/mL in plasma and 5-1000 ng/mL in DBS. This method was applied to monitor anlotinib exposure levels in patients with advanced biliary tract cancer (BTC) and non-small cell lung cancer (NSCLC). RESULTS: ) of anlotinib was highly variable among BTC patients with coefficients of variation (CV) of 47.5%. DBS and venous blood samples were also collected from NSCLC patients to determine whether DBS sampling is a viable alternative sampling approach. Pearson correlation coefficient (R) between DBS and plasma concentration was 0.985. Bland-Altman plot demonstrated that the difference between estimated and measured plasma concentration was -2.9%. And 87% of sample pairs had a maximal deviation of ±20%. CONCLUSIONS: Anlotinib exhibits a high inter-individual variability in plasma exposure, and DBS sampling could be a promising tool for TDM of anlotinib.