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Tuesday, October 20, 2015

Why anti-cancer antibody, cixutumumab, does not work in patients

Drug resistance is a major impediment in medical oncology. Recent studies have emphasized the importance of the tumor microenvironment (TME) to innate resistance, to molecularly targeted therapies.
In this study, authors investigate the role of TME in resistance to cixutumumab, an anti-IGF-1R monoclonal antibody that has shown limited clinical efficacy. They show that treatment with cixutumumab accelerates tumor infiltration of stromal cells and metastatic tumor growth, and decreases overall survival of mice.
Cixutumumab treatment stimulates STAT3-dependent transcriptional upregulation of IGF-2 in cancer cells and recruitment of macrophages and fibroblasts via paracrine IGF-2/IGF-2R activation, resulting in the stroma-derived CXCL8 production, and thus angiogenic and metastatic environment.
Silencing IGF-2 or STAT3 expression in cancer cells or IGF-2R or CXCL8 expression in stromal cells significantly inhibits the cancer–stroma communication and vascular endothelial cells’ angiogenic activities.
These findings suggest that blocking the STAT3/IGF-2/IGF-2R intercellular signalling loop may overcome the adverse consequences of anti-IGF-1R monoclonal antibody-based therapies.…