(1147-D) A validated Method For the Quantification of Protacs – 3 – Gefitibib in Rat Plasma to Support Rodent PK Studies
Tuesday, February 6, 2024
12:00 PM – 1:00 PM EST
Location: Exhibit Halls AB
Abstract: mobilizing the ubiquitin–proteasome system to achieve proteasome-mediated degradation of the target protein via the cell machinery. Protacs consist of three main components i) target binding moiety, ii) linker and iii) ubiquitin E3 ligase binding moiety. They can be considered “large small molecule” and as such share many of the attributes such as synthesis scale up, cost of manufacture, shelf life, stability and route of administration. Protacs eliminate all functions of the protein, hence provide differentiated pharmacology and do not require target binding moieties that inhibit protein function. They also significantly increase the number of “drugable” proteins opening up the possibility for new safer medicines.
Gefitinib is a tyrosine kinase inhibitor for the treatment of non-small cell lung cancer, it is a potent EGFR inhibitor interrupting cell signalling, it was withdrawn in 2012. To compare the pharmacokinetics of Protacs-3- gefitinib with that of gefitinib we developed a rapid reversed – phase LC-MS/MS based assay for the quantification both compounds in a single 3- min methodology. The samples were prepared by protein precipitation of 10 µL of plasma with 40 µL acetonitrile using gefitinib (d6) as an internal standard (50ng/mL). The limit of detection for Protacs-3-gefitinib was determined to be 20pg/mL with a dynamic range of 20 – 10,000pg/mL. Gefitinib showed a limit of detection of 100pg/mL with a dynamic range of 0.1 – 1,000ng/mL. The assay was subjected to the 3- day validation with a CV ranging from 5 – 10%. Freezethaw studies (n = 4) show no reduction in measure concentration for the batch QCs between sampling occasions. This methodology was applied to the analysis of rat and mouse plasma samples following the IV administration of gefitinib and Protacs-3-gefitinib at 10mg/kg to determine the pharmacokinetics and detect major metabolites.