Strategies for effective development of ultra-sensitive LC-MS/MS assays: application to a novel STING agonist.

The continual need for the development and validation of ultra-sensitive (low pg/ml) LC-MS/MS assays in the pharmaceutical industry is largely driven by the ultra-low analyte exposure or very low sample volume. Strategies and systematic approaches for sensitivity enhancement are provided which cover all aspects of a LC-MS/MS bioanalysis. A case study where such strategies were applied for the validation of a 5.0 pg/ml assay for a STING agonist is discussed. Analytical protocols were developed to extract analytes from large volume of plasma samples (600 and 400 μl) with high throughput. The guidance provided in this publication can serve as a resource to influence LC-MS/MS method development activities.