Evaluation of tissue perfusion (tumor, spleen, heart) in mice after administration of AVE8062, a tumor vascular-targeting agent
Authors: Magali Guffroy, Claire Dally, Patricia Vrignaud, Eric Beys, Marie-Christine Bissery
Journal: Cancer Research (2004)

Proc Amer Assoc Cancer Res, Volume 45, 2004

5438 

AVE8062, a tumor vascular-targeting agent, has been shown to reduce blood flow in different tissues (Jpn. J. Cancer Res. 90, 1026, 1999) and to induce tumor necrosis in tumor-bearing mice (AACR 2002, # 781). Our goal was to determine the time-course and dose-response of perfusion changes in tumor versus heart and spleen, using the perfusion marker Hoechst 33342. The tumor model and dosages were selected on the basis of a dose-response efficacy trial. BALB/c female mice bearing advanced stage colon adenocarcinoma C51 were administered twice, 4 days apart, with iv doses ranging from 22.3 to 93.5 mg/kg/inj. The highest non toxic dose (HNTD) of AVE8062 (58 mg/kg/inj) was found active with 1.4 log cell kill (log CK = tumor growth delay / 3.32 x tumor doubling time) and induced 33 % complete regressions (AACR 2002, # 780). In the perfusion studies, C51-bearing mice (n = 5) received a single iv dose of AVE8062. For the time-course study, perfusion changes were evaluated 30 mn, 1 h, 3 h, 6 h, 24 h and 48 h after administration of AVE8062 at 58 mg/kg (HNTD). For the dose-response study, the sampling time was 6 h post dosages equal or below the HNTD (5.8, 11.6, 29 or 58 mg/kg). Five minutes before necropsy, mice were injected iv with the DNA-binding fluorescent dye Hoechst 33342 at 20 mg/kg to evaluate tissue perfusion. Tumor, heart and spleen were quickly collected and frozen. Tissue sections were evaluated under UV light and fluorescence signals were analysed using an image analysis system. In the time-course study, AVE8062 induced a rapid reduction in tumor perfusion that was evident by 30 mn and maximal at 3-6 h, with ensuing extensive tumor necrosis by 24 h. In the spleen, marked reduction in tissue perfusion was seen by 6 h that was completely reversible by 48 h and not associated with any morphological changes. Heart changes were limited to a focal area of decreased left ventricular perfusion in a single mouse at 24 h. In the dose-response study, AVE8062 induced dose-related reductions in tissue perfusion in the tumor and spleen at all doses and in the heart at 58 mg/kg only. Perfusion changes in the tumors were overall moderate at 5.8 mg/kg and severe at 11.6 mg/kg and above, with almost complete abrogation of tumor blood flow in all mice at these latter doses. However, the peritumoral tissues remained adequately perfused in all cases, which is consistent with an increased susceptibility of tumor vasculature. In the spleen, perfusion changes were overall marginal at 5.8 mg/kg and marked at 58 mg/kg. Heart changes were limited to a small focus of decreased left ventricular perfusion in a single mouse at 58 mg/kg. In conclusion, AVE8062 induced rapid and irreversible blood flow shut down in tumors leading to extensive necrosis by 24 h. In other normal tissues, perfusion changes were either completely reversible (spleen) and/or observed only at high doses (heart).