Continuous Flow Paper Spray Ionization Mass Spectrometry for In-Depth Characterization of Anticancer Drugs in Tissues: Addressing Mass Spectral Complexity

We introduced continuous flow paper spray ionization mass spectrometry (CFPSI MS) for the rapid detection and characterization of anticancer drugs in solid tissue samples. CFPSI is a paper spray-based semiquantitative method using continuous flow of an internal standard to quantify the amounts of drugs released from the tissue samples. Using patient-derived xenograft (PDX) mouse model tissue samples, we observed differential absorption of three anticancer drugs, palbociclib, copanlisib, and olaparib. Palbociclib was found to be bioabsorbed in the tissue samples to the largest extent. Tandem mass spectrometric analysis explored the in-source chemical reactivity of these drugs, leading to significant spectral complexity. Our findings highlight the importance of careful spectral interpretation in complex biological matrices and support the development of future rapid quantitative CFPSI analysis of these drugs in tissue samples.