Demonstration in animal and human of AVE8062-induced tumor blood flow shutdown using dynamic contrast enhanced-ultrasonography (DCE-US).
Authors: Erwan Jouannot, Chantal Carrez, Nathalie Lassau, Pascale Lejeune, Brigitte Demers, Patricia Vrignaud, Marie-Christine Bissery
Journal: Cancer Research (2007)

LB-328  AVE8062 is a synthetic, water-soluble Combretastatin A4 analog, showing potent antitumor efficacy in a broad panel of tumor models. It is currently evaluated in phase I combination trials.  AVE8062 inhibits tubulin polymerization through reversible binding at the colchicine site. In vivo, it induces a rapid tumor blood flow shutdown, and severe tumor necrosis (Proc AACR, 2004), leading to tumor regressions (Proc AACR, 2002). Tumor perfusion arrest post treatment has been previously documented using Hoechst labeling of the tumor vessels (Proc AACR, 2005). The AVE8062 functional effect on tumor vascularization was previously investigated using dynamic contrast enhanced-ultrasonography (DCE-US) in a kinetic study (Proc AACR, 2006).  >The goal of the present work was to expand kinetic evaluation, to explore image analysis methodology in order to perform tumor mapping for perfusion, and to translate the preclinical findings in the clinical setting.  >The compound was administered iv at 41 mg/kg (70% of the highest non-toxic dose) to mice bearing established B16 melanoma tumors. Ultrasound examination after contrast agent injection was performed at high frequency (7-14 MHz probe) with an Aplio® (Toshiba). AVE8062 effect on tumor perfusion was documented prior to (baseline) and at different times after compound administration (5min, 1, 6, 24, and 48h). Contrast uptake within the entire tumor was quantified with a dedicated software (CHI-Q®, Toshiba). Parameters were extracted from the time intensity curves expressed in raw data using MatLab® (Mathworks). Following contrast agent injection, a significant decrease (~50%) in the Area Under Curve was quantified as early as 5min post AVE8062 injection; this impact on perfusion was maintained for the first 24h, and was reversible. Power Doppler of large vessels within the tumor enabled real-time imaging of vascular collapse. Signal processing of the raw data allowed analysis of perfusion on a pixel level and creation of parametric images from which tumor maps could be drawn. These maps show a dramatic impact of AVE8062 on tumor perfusion in the central area and a more limited impact in the periphery.  >Lastly, this imaging technique was further used in AVE8062 single agent and cytotoxic combination clinical trials. At increasing doses from 11.5 mg/m² up to 30 mg/m², patients with different solid tumor types were imaged and a significant decrease in tumor blood perfusion was observed at 6 and 24h after drug infusion, repeated every 2 cycles. These results demonstrate that DCE-US, in combination with perfusion software, is a sensitive and non invasive technique that can be used to evaluate functional consequences of vascular-disrupting agents therapy in animal models. The confirmation in man of the findings observed in mouse indicates that DCE-US can be successfully used as a translational technique.