Determination of Zipalertinib Using LC‐ESI‐MS/MS and Application to Pharmacokinetic Study in Mice

Zipalertinib is a novel, irreversible EGFR inhibitor for the treatment of non-small cell lung cancer (NSCLC) with EGFR exon 20 insertion mutations. A new sensitive, specific and rapid LC-ESI-MS/MS method has been developed and validated to quantify zipalertinib in mouse and human dried blood spot (DBS) with filgotinib used as an internal standard (IS) in accordance with regulatory guidelines. Quantification of zipalertinib and IS were achieved by triple quad mass spectrometer operated under the multiple reaction-monitoring mode (MRM) using positive ion scan mode and parent-daughter mass to charge ion transition of m/z 397.2 → 326.0 and m/z 426.2 → 291.2, respectively. The linear response function of zipalertinib was determined in the concentration range from 0.741 to 1111 ng/mL (r > 0.990). No matrix effect and carry over were observed. Hematocrit did not influence DBS zipalertinib concentrations. Zipalertinib demonstrated stability under various storage conditions. This method was successfully used to study the in vitro metabolic profiles and in vivo pharmacokinetics of zipalertinib in mice. An excellent correlation was observed between DBS and plasma concentrations, indicating DBS can be used as an alternative for plasma for pharmacokinetic analysis.