Establishment and validation of a sensitive LC–MS/MS method for the quantification of KRAS^G12C protein PROTAC molecule LC‐2 in rat plasma and its application to in vivo pharmacokinetic studies of LC‐2 PEGylated liposomes

Abstract

LC‐2, is a molecule of proteolysis targeting chimeras (PROTACs), with a large molecular weight, poor water solubility and low system bioavailability, which was designed to degrade KRASG12C protein. In this study, LC‐2 PEGylated liposomes were developed and characterized. Moreover, a rapid and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method in rat plasma was established and effectively utilized for an in vivo pharmacokinetic investigation. LC‐2 PEGylated liposomes with better properties were prepared by an improved ethanol injection method. The chromatographic separation was achieved on an Agilent Eclipse XDB‐CN column (100 × 2.1 mm, 3.5 μm) with acetonitrile–ammonium deionized water (5 mm; 80:20, v/v) at a flow rate of 0.5 ml/min. The mass spectra of LC‐2 and the IS (gefitinib) were obtained at m/z 1132.5 → 626.4 and 447.1 → 128.2, respectively. The pharmacokinetic study was carried out by analyzing plasma concentrations of LC‐2 solution or produced LC‐2 PEGylated liposomes in rats using the developed and validated method. The pharmacokinetic results indicate that PEGylated liposome‐encapsulation protected LC‐2 from the influence of endogenous protein binding, improved insolubility, prolonged half‐life and increased system bioavailability. This study provides a feasible solution for future preclinical and clinical studies of LC‐2 and/or other PROTACs.