High-Performance Liquid Chromatography for Therapeutic Drug Monitoring of Serum Lenvatinib

This study aimed to develop and validate a high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection for the routine therapeutic drug monitoring (TDM) of lenvatinib in serum, particularly for patients with radioiodine-refractory thyroid cancer. The authors recognized the clinical benefit of TDM for lenvatinib to optimize treatment efficacy and minimize adverse effects, especially when advanced mass spectrometry facilities are unavailable. The method involved solid-phase extraction of serum specimens spiked with an internal standard. Lenvatinib and the internal standard were then separated using a conventional octadecylsilyl silica column under isocratic elution conditions, with a mobile phase comprising 0.02 mol/L sodium phosphate (pH 6.7) and acetonitrile (50/50, vol/vol) at a flow rate of 1.0 mL/min. Detection was performed at 244 nm. Clinical validation was conducted using serum samples from five patients. The developed method demonstrated excellent linearity, recovery, and precision, making it a sensitive and reliable alternative for lenvatinib TDM in clinical settings.

This study aimed to develop and validate a high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection for the routine therapeutic drug monitoring (TDM) of lenvatinib in serum, particularly for patients with radioiodine-refractory thyroid cancer. The authors recognized the clinical benefit of TDM for lenvatinib to optimize treatment efficacy and minimize adverse effects, especially when advanced mass spectrometry facilities are unavailable. The method involved solid-phase extraction of serum specimens spiked with an internal standard. Lenvatinib and the internal standard were then separated using a conventional octadecylsilyl silica column under isocratic elution conditions, with a mobile phase comprising 0.02 mol/L sodium phosphate (pH 6.7) and acetonitrile (50/50, vol/vol) at a flow rate of 1.0 mL/min. Detection was performed at 244 nm. Clinical validation was conducted using serum samples from five patients. The developed method demonstrated excellent linearity, recovery, and precision, making it a sensitive and reliable alternative for lenvatinib TDM in clinical settings. Research Background and Significance Therapeutic drug monitoring (TDM) is a critical clinical practice aimed at individualizing drug dosage to maximize therapeutic efficacy while minimizing toxicity. Lenvatinib, a multi-kinase inhibitor used primarily in the treatment of radioiodine-refractory thyroid cancer, demands precise monitoring due to its narrow therapeutic window and potential for adverse effects. Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) is often considered the gold standard for quantifying drugs like lenvatinib in biological matrices, many clinical laboratories lack access to these advanced and costly instruments. This gap underscores the