[Revision of therapeutic index for targeted treatment in kidney cancer: What if toxicity could predict efficacy?].

Since 2006, new treatments as targeted therapies (anti angiogenic and mTOR inhibitors) are prescribed in renal cell cancer. Toxicity of these treatments is well known by clinicians. Occurrence of these side effects has been associated with anti tumoral efficacy. High blood pressure, hypothyroïdie and hand foot syndrome were reported to be predictive of anti tumoral response. Fatigue and hyponatremia are still largely discussed. Moreover, non infectious pneumonia, which frequently occurs with mTOR inhibitors, is associated with clinical benefit. The main objective of treatment of advanced kidney cancer, specially renal cell cancer, is obtaining clinical benefit (stabilization and response) with a chronic evolution of the disease. This prolong exposure to drugs, according to their toxicity profile, often contributes to dose reduction, moreover interruption of treatment, potentially associated with a loss of control of disease. Thus, the adverse effects, described hereby, may be considered as « positive events », predicting efficacy, and thus looked for… Moreover, the sequential approach, with new drugs, emphasizes the need of defining the optimal sequence. Thus, because of the lack of molecular biomarkers to date, this predictives secondary effects may help for selecting the therapeutic strategy.