Anti-angiogenic Therapy-Mediated Endothelial Damage: A Driver of Breast Cancer Recurrence?

ABSTRACT

Anti-angiogenic therapy was conceived originally as a silver bullet able to maintain tumor dormancy indefinitely. By targeting new blood vessel formation, anti-angiogenic agents were expected to suppress the growth of any type of primary or metastatic tumor, independent of their subtype or genetic landscape. However, more that 20 years after the first anti-angiogenic preclinical trial, the astonishing inhibition of metastatic outgrowth originally observed in mouse models never translated into clinics. Indeed, whereas anti-angiogenic agents (sometimes) prolong progression-free survival, they fail to impact overall survival, particularly in breast cancer. This observation revealed to be true in early- and advanced-stage breast cancer patients treated either in adjuvant or neo-adjuvant settings, suggesting that the effect of anti-angiogenic therapy on repressing growth of overt metastases - and also on preventing outgrowth of disseminated tumor cells and micrometastases - is limited. What are the reasons underlying this failure? And, more importantly, is there still room for improvement?