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The antioxidant properties of α-tocopherol have been proposed to play a beneficial chemopreventive role against cancer. However, emerging data also indicate that it may exert contrasting effects on the efficacy of chemotherapeutic treatments when given as dietary supplement, being in that case harmful for patients. This dual role of α-tocopherol and, in particular, its effects on the efficacy of anticancer drugs remains poorly documented. For this purpose, we studied here, using high throughput flow cytometry, the direct impact of α-tocopherol on apoptosis and cell cycle arrest induced by different cytotoxic agents on various models of cancer cell lines in vitro. Our results indicate that physiologically relevant concentrations of α-tocopherol strongly compromise the cytotoxic and cytostatic action of various protein kinase inhibitors (KI), while other classes of chemotherapeutic agents or apoptosis inducers are unaffected by this vitamin. Interestingly, these anti-chemotherapeutic effects of α-tocopherol appear to be unrelated to its antioxidant properties since a variety of other antioxidants were completely neutral toward KI-induced cell cycle arrest and cell death. In conclusion, our data suggest that dietary α-tocopherol could limit KI effects on tumour cells, and, by extent, that this could result in a reduction of the clinical efficacy of anti-cancer treatments based on KI molecules.

By interfering with signal transduction events that control cell proliferation and fate, kinase inhibitors (KIs) hold promise as anticancer agents. Nevertheless, the functional role of a kinase depends on the cellular context and hence kinase inhibition in off-target cells could lead to side effects. For instance, this context dependence renders many KIs potentially cardiotoxic since inhibition of primary cancer targets such as ABL, RAF1 or AMPK recruits pro-apoptotic pathways in cardiomyocytes. Motivated by these observations, we propose a mode of 'therapeutic editing' where one drug (the editor) suppresses the side effect promoted by the primary drug as it impacts off-target cells. Editor and primary drug have overlapping therapeutic impact, and the editor suppresses the downstream propagation of toxicity-related signaling.

An expanding knowledge of the signalling pathways involved in the cell cycle has led to great improvements in the understanding of the molecular events involved in carcinogenesis. The past decade has seen substantial advances with the introduction of several classes of targeted therapeutics for the treatment of various cancers and autoimmune disorders. However, the question arises as to whether pregnant women can take advantage of these new treatments in view of the potential risks to the fetus. Published work suggests that biological agents, like traditional treatments, have the potential to affect the fetus, and should, therefore, be used with caution during pregnancy. However, when targeted treatment is clearly indicated the magnitude of the risk to the fetus might not reach that of standard chemotherapy. In circumstances where better alternative treatments do not exist, or where failure to use targeted treatments would result in suboptimum patient care or survival, the risk-benefit analysis might favour the use of potentially effective molecular treatment during pregnancy.