In:
Cancer Research, American Association for Cancer Research (AACR), Vol. 70, No. 8_Supplement ( 2010-04-15), p. 2768-2768
Abstract:
The novel agent, BNC105, is a tubulin polymerization inhibitor which acts as a vascular disruption agent (VDA). BNC105 exhibits 100-fold selectivity for activated endothelial cells compared to quiescent endothelial cells, providing a large differential between effects on cancer vasculature and normal vasculature. We developed a tubulin fractionation assay that enables evaluation of tubulin polymerisation changes in peripheral blood mononuclear cell samples (PBMCs) obtained from patients treated with BNC105. The assay capitalizes on the mass differences between polymerized and depolymerised tubulin to separate each fraction in a density gradient by ultracentrifugation. Experimental conditions during the extraction process were optimised to maintain the polymerisation state of tubulin. This optimisation was carried out in cell lines and PBMCs from healthy volunteers. Critical parameters include temperature, GTP concentration, DMSO concentration, pH, and buffer density. Tubulin monomer and polymer extracts were resolved using SDS-PAGE and transferred onto nitrocellulose membranes followed by detection using βI tubulin specific antibodies. The tubulin bands were analysed by densitometry and normalized to an actin loading control. Following exposure of cell lines or PBMCs to tubulin polymerisation inhibitors for a period of 60 minutes, the depolymerised tubulin fraction increased, while the polymerised tubulin fraction decreased. Conversely, exposure to tubulin polymerizing agents caused a greater proportion of tubulin to appear in the polymerized fraction. We used this method to evaluate the tubulin polymerisation status in PBMC samples obtained from cancer patients treated with BNC105. Samples were obtained prior to dosing and at 1, 2, 3-5, 7, and 24 hours post-dosing. Based on the data obtained, BNC105 treatment caused an 80% reduction in the polymerised tubulin fraction at the 1, 2 and 3-5 hour sampling time points. The amount of tubulin in the polymerised fraction returned to pre-dose levels by the 7 hour post-dose time point. The pharmacokinetic profile of BNC105 shows a steep curve reaching Cmax at around 20 minutes post-administration, followed by plasma clearance with no BNC105 detectable after the 7 hour time point. The pharmacokinetics of BNC105 supports our tubulin depolymerisation data with respect to response time and the subsequent recovery period. These results were reproducible, and have shown a similar pattern in all patients tested to date. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2768.
Type of Medium:
Online Resource
ISSN:
0008-5472
,
1538-7445
DOI:
10.1158/1538-7445.AM10-2768
Language:
English
Publisher:
American Association for Cancer Research (AACR)
Publication Date:
2010
detail.hit.zdb_id:
2036785-5
detail.hit.zdb_id:
1432-1
detail.hit.zdb_id:
410466-3
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