Reappraisal of the Role of Bevacizumab in the Therapeutic Strategy in Advanced Renal Cell Carcinoma

The world of targeted therapies in kidney cancers: pitfalls, tips and tricks

In the past few years, metastatic renal cell carcinoma prognosis was improved by the development of molecular targeted therapies (TTs). At the metastatic stage, the tolerance to treatment is a major concern, not only because of the challenge of the efficacy/toxicity ratio improvement but also because of the importance of an optimal adherence to oral treatments. The present case series relates the issues of dealing with uncommon and sometimes never described side effects of sunitinib and sorafenib. The first case report deals with grade 3 vomiting during hemodialysis with concurrent administration of sunitinib. The second case is an iterative gout attack induced by sunitinib. The third case presents a grade 3 scalp dysesthesia with sorafenib. The fourth case includes an astonishing efficacy of metronomic (ie, low doses during a long period of time) bevacizumab in monotherapy. Multidisciplinary management and systematic reporting of unexpected efficacies and toxicities are needed to better understand TTs real therapeutic index. Although TTs revolutionized metastatic renal cell cancer prognosis, they also brought about previously unknown side effects. Identification and management of these off-target effects may be tricky, and therefore, comedication must be wisely chosen. As the physiopathology of these side effects is still unclear, multidisciplinary management and systematic reporting of toxicities are essential.

Tumor cell-mediated neovascularization and lymphangiogenesis contrive tumor progression and cancer metastasis

Robust neovascularization and lymphangiogenesis have been found in a variety of aggressive and metastatic tumors. Endothelial sprouting angiogenesis is generally considered to be the major mechanism by which new vasculature forms in tumors. However, increasing evidence shows that tumor vasculature is not solely composed of endothelial cells (ECs). Some tumor cells acquire processes similar to embryonic vasculogenesis and produce new vasculature through vasculogenic mimicry, trans-differentiation of tumor cells into tumor ECs, and tumor cell-EC vascular co-option. In addition, tumor cells secrete various vasculogenic factors that induce sprouting angiogenesis and lymphangiogenesis. Vasculogenic tumor cells actively participate in the formation of vascular cancer stem cell niche and a premetastatic niche. Therefore, tumor cell-mediated neovascularization and lymphangiogenesis are closely associated with tumor progression, cancer metastasis, and poor prognosis. Vasculogenic tumor cells have emerged as key players in tumor neovascularization and lymphangiogenesis and play pivotal roles in tumor progression and cancer metastasis. However, the mechanisms underlying tumor cell-mediated vascularity as they relate to tumor progression and cancer metastasis remain unclear. Increasing data have shown that various intrinsic and extrinsic factors activate oncogenes and vasculogenic genes, enhance vasculogenic signaling pathways, and trigger tumor neovascularization and lymphangiogenesis. Collectively, tumor cells are the instigators of neovascularization. Therefore, targeting vasculogenic tumor cells, genes, and signaling pathways will open new avenues for anti-tumor vasculogenic and metastatic drug discovery. Dual targeting of endothelial sprouting angiogenesis and tumor cell-mediated neovascularization and lymphangiogenesis may overcome current clinical problems with anti-angiogenic therapy, resulting in significantly improved anti-angiogenesis and anti-cancer therapies.