Pharmacokinetics of Rac inhibitor EHop-016 in mice by ultra-performance liquid chromatography tandem mass spectrometry

• A rapid and sensitive method was validated for detection of EHop-016 in mouse plasma by UPLC/MS/MS.
• EHop-016 pharmacokinetics in mice was quantified using a dosing scheme of 10, 20, and 40 mg/kg BW.
• EHop-016 is bioavailable after intraperitoneal and oral administration.

The Rho GTPase Rac is an important regulator of cancer cell migration and invasion; processes required for metastatic progression. We previously characterized the small molecule EHop-016 as a novel Rac inhibitor in metastatic breast cancer cells and recently found that EHop-016 was effective at reducing tumor growth in nude mice at 25 mg/kg bodyweight (BW). The purpose of this study was to compare the pharmacokinetics and bioavailability of EHop-016 at different dosages in a single dose input scheme (10, 20 and 40 mg/kg BW) following intraperitoneal (IP) and oral gavage (PO) administration to nude mice. We developed and validated a rapid and sensitive method for the quantitation of EHop-016 in mouse plasma by ultra high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC/MS/MS). Separation was carried out on an Agilent Poroshell 120 EC-C18 column (3.0 mm × 50 mm) using organic and aqueous mobile phases. EHop-016 was identified from its accurate mass and retention time from the acquired full-scan chromatogram and quantified by its peak area. The validated method was linear (R2 > 0.995) over the range of 5–1000 ng/mL (1/x2 weighting). Pharmacokinetic parameters were obtained by non-compartmental analysis using WinNonlin®. The area under the curve (AUC0–∞) ranged from 328 to 1869 ng h/mL and 133–487 ng h/mL for IP and PO dosing, respectively. The elimination half-life (t1/2) ranged from 3.8–5.7 h to 3.4–26.8 h for IP and PO dosing, respectively. For both IP and PO administration, the AUC0–∞values were proportional to the tested doses demonstrating linear PK profiles. The relative bioavailability of EHop-016 after oral gavage administration ranged from 26% to 40%. These results support further preclinical evaluation of EHop-016 as a new anti-cancer therapy.