Improving immunotherapy outcomes with anti-angiogenic treatments and vice versa

Immunotherapies have revolutionized medical oncology following the remarkable and, in some cases, unprecedented outcomes observed in certain groups of patients with cancer. Combination with other therapeutic modalities, including anti-angiogenic agents, is one of the many strategies currently under investigation to improve the response rates and duration of immunotherapies. Such a strategy might seem counterintuitive given that anti-angiogenic agents can increase tumour hypoxia and reduce the number of blood vessels within tumours. Herein, we review the additional effects mediated by drugs targeting VEGF-dependent signalling and other pathways, such as those mediated by angiopoietin 2 or HGF, which might increase the efficacy of immunotherapies. In addition, we discuss the seldom considered possibility that immunotherapies, and immune-checkpoint inhibitors in particular, might increase the efficacy of anti-angiogenic or other types of antivascular therapies and/or promote changes in the tumour vasculature. In short, we propose that interactions between both therapeutic modalities could be considered a 'two-way street'.