Development of High-Throughput Quantitative Imaging Mass Spectrometry for Analysis of Drug Distribution in Tissues

Matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS) is applied in drug discovery and development. A high-throughput quantitative MALDI-IMS methodology was developed to confirm whether epertinib is superior to lapatinib in penetrating brain metastases using intraventricular injection mouse models (IVMs) of human EGFR2 (HER2)-positive breast or T790M-EGFR-positive lung cancer cells. A simple calibration curve was prepared for each compound via spotting standard solutions without using blank tissue sections or blank tissues onto the same glass slide as the epertinib or lapatinib brain section samples. Quantitative MALDI-IMS was performed via coating a glass slide with a MALDI matrix solution containing each internal standard solution. The samples of calibration curve and brain section were analyzed using a linear ion trap mass spectrometer with a MALDI ion source. Epertinib and lapatinib responses were strongly linear, with a wide dynamic range and low variation (relative standard deviation [RSD] < 20%) among the individual concentrations. Epertinib and lapatinib were sufficiently extracted from brain sections after oral administration in a breast cancer IVM. The quantitative MALDI-IMS results revealed that the epertinib concentrations administered to the brain sections in the lung cancer IVM were similar to those measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Quantitative MALDI-IMS, owing to its high reproducibility and throughput, is useful for selecting drug candidates in the early stages of discovery and development, enabling efficient and rapid screening of candidate compounds as well as an understanding of the mechanisms of drug efficacy, toxicity, and pharmacokinetics/pharmacodynamics.