Quantitative determination of a potent geranylgeranyl diphosphate synthase inhibitor using LC–MS/MS: Derivatization and application

Abstract

An isomeric mixture of homogeranyl/homoneryl triazole bisphosphonates (VSW1198) has previously been shown to be a potent inhibitor of geranylgeranyl diphosphate (GGDP) synthase (GGDPS) and of therapeutic interest for the treatment of multiple myeloma. We have developed and validated a selective and sensitive liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantitation of both the E- and Z- isomers of VSW1198 in cell culture media, mouse plasma and tissues. VSW1198 and internal standard are extracted from the bio-matrices by solid-phase extraction, followed by derivatization using trimethylsilyldiazomethane. The chromatographic separation of analytes was achieved on a Phenomenex Gemini NX column (150 mm * 2.0 mm, 5 μ) with gradient elution using 0.1% acetic acid and methanol/acetonitrile (1:1) as the mobile phase at a flow rate of 0.2 mL/min. Derivatized analytes were ionized with an electrospray ionization source in positive multiple reaction monitoring (MRM) mode and quantitated using MS/MS. The MS/MS response was linear over the concentration range from 0.38-1500 and 0.13-500 ng/mL for the E- and Z-isomers, respectively. The within- and between-day precision (relative standard deviation, % RSD) and accuracy were within the acceptable limits per FDA guidelines. The validated method was used for quantitative determination of the compounds in preclinical studies focused on the development of VSW1198 as a novel anti-cancer agent.

Preclinical investigation of a potent geranylgeranyl diphosphate synthase inhibitor

“…Tissue samples (liver, kidney, spleen, lung, heart, brain, and bone marrow) were collected at 2, 8, 24, 48, and 72 hours from mice injected IV with 0.5 mg/kg VSW1198. VSW1198 was extracted from tissues and quantified via LC-MS/MS as previously described [8]. VSW1198 was detected in all studied tissues including bone marrow, brain, liver, spleen, and kidney (Figure 6 and Table S2).…”

“…Tissues were collected at six time points (2, 8, 24, 48, 72, and 168 hours). VSW1198 was extracted from plasma and tissue samples via solid phase extraction followed by derivatization with diazomethane, and analyzed via LC-MS/MS as previously described [8].…”

“…A compound with known metabolism was used as a positive control. All samples were processed and derivatized according to our plasma sample processing method and supernatant (10 μL) was injected for LC-MS/MS analysis [8]. The in vitro metabolic elimination rate constant was determined from the first order plot of natural logarithm of area ratio versus time.…”

Simultaneous Quantitation of Isoprenoid Pyrophosphates in Plasma and Cancer Cells Using LC-MS/MS

“…The RAM-1147 (structural analogue) was selected as the IS in this method [28]. The IS selected for this method is an isoprenoid triazole bisphosphonate, and therefore serves as a structural analogue to IsoP.…”

“…Mevalonate (MVA), IPP, GPP, FPP and GGPP were obtained from Sigma-Aldrich (St Louis, MO, USA). Professor David Wiemer at the University of Iowa kindly provided the RAM1147 used as the assay internal standard (IS) [28]. LCMS-grade methanol (MeOH) and acetonitrile (ACN) along with HPLC grade formic acid (FA), ammonium carbonate, and ammonium hydroxide were obtained from Fisher Scientific (Fair Lawn, NJ, USA).…”