


Preclinical models and clinical observations have indicated that Avastin can cause regression of existing tumour vasculature. Significant reductions in tumour vascular volume and density following a single infusion of Avastin alone have been reported.5,6
In a preclinical model using human tumour xenografts, a single bolus (0.2mL) infusion of Avastin resulted in an 80% decrease in tumour vascular volume.5 This reduction was observed rapidly, within 24 hours of infusion.
Reduction in MVD following administration of Avastin has also been observed in the clinical setting. In a phase I evaluation, a single infusion of Avastin significantly (p<0.05) decreased MVD in patients with rectal cancer.6
In terms of clinical significance, regression of tumour vasculature by Avastin can increase tumour response to cytotoxic chemotherapy. This effect is discussed in more detail here.