Liquid chromatography-tandem mass spectrometry for pharmacokinetics evaluation of AZD5305, a selective PARP1 inhibitor, in mice

Abstract Poly (ADP-ribose) polymerase (PARP) inhibitors that are effective against ovarian and breast cancers with breast cancer susceptibility gene (BRCA) mutations have undesirable side effects, such as hematological toxicity. AZD5305, a selective PARP1 inhibitor currently in Phase 1/2 clinical trials, may avoid the side effects caused by PARP2. However, the in vivo pharmacokinetic characteristics of AZD5305 and its bioanalytical methods are unknown. Therefore, a method based on liquid chromatography with tandem mass spectroscopy (LC–MS/MS) was developed and validated to quantify AZD5305 in plasma of mice. Optimal chromatographic separation in terms of peak intensity and symmetry was acquired using a 4-µm Polar-RP 80 Å (2.0 × 150 mm) column with ammonium acetate (5 mM) in distilled water–acetonitrile (50:50, v/v). The retention times of AZD5305 and internal standard (IS; olaparib) were 1.82 min and 1.99 min, respectively. Detection was carried out via triple quadrupole mass spectrometry in positive ion mode employing multiple reaction monitoring transitions at m / z 407.0 → 376.0 for AZD5305 and m / z 435.0 → 281.2 for the IS. The LC–MS/MS method was linear in the range 1–1000 ng/mL with a correlation coefficient ≥ 0.990 and showed acceptable values of major parameters including accuracy, precision, and recovery. Additionally, AZD5305 showed high stability under various conditions. The in vivo and in vitro pharmacokinetics of AZD5305 were successfully characterized by employing the validated LC–MS/MS method. A high level of drug exposure and linear pharmacokinetics were observed after intravenous (IV) bolus and oral administration (PO) of AZD5305 at 0.1–1 mg/kg and 0.1–3 mg/kg, respectively. The bioavailability was close to 100%, and the metabolic stability of AZD5305 in hepatic microsomes of mice and humans was very high. These results may contribute to the improvement of PARP inhibitors that are used to treat malignancies originating from BRCA mutations.