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.