Anti-lactadherin antibodies in anti-angiogenic cancer therapy of breast cancer stem cells

14138 Background: Angiolix (Hu-Mc3) is a humanized monoclonal antibody that recognizes a migrating adhesion molecule called Lactadherin. This novel antibody has a high affinity for its antigen and recognizes an epitope on Lactadherin which interacts with the the ’RGD’- motif found on integrin receptors on newly formed endothelial cells. Lactadherin binding leads to signalling via a VEGF-independent integrin receptor signalling cascade leading to vascular endothelial cell profileration. Lactadherin binding may also increase the potency of VEGF-VEGF receptor signalling. Methods: We studied the expression of Lactadherin on breast cancer cell lines, the biodistribution of Angiolix in human breast cancer xeografts and its ability to inhibit tumor growth in vivo. Results: Our data show that tumor cells express lactadherin in vivo and that Angiolix could achieve more than 75% growth inhibition of human breast cancer growing as xenografts . Conclusions: In view of the recent finding that cancer stem cells can over-express the pro-angiogenic VEGF and make a major contribution to tumor vasculature proliferation leads to the possibility that Angiolix may be able to act to specifically target breast cancer stem cell and cause tumor regression by blocking the growth of tumor vasculature by its ability to neutralise Lactadherin-integrin receptor binding. [Table: see text]