Efficacy and safety of sorafenib in advanced renal cell cancer and validation of Heng criteria

Sorafenib resistance in hepatocarcinoma: role of hypoxia-inducible factors

Sorafenib, a multikinase inhibitor with antiproliferative, antiangiogenic, and proapoptotic properties, constitutes the only effective first-line drug approved for the treatment of advanced hepatocellular carcinoma (HCC). Despite its capacity to increase survival in HCC patients, its success is quite low in the long term owing to the development of resistant cells through several mechanisms. Among these mechanisms, the antiangiogenic effects of sustained sorafenib treatment induce a reduction of microvessel density, promoting intratumoral hypoxia and hypoxia-inducible factors (HIFs)-mediated cellular responses that favor the selection of resistant cells adapted to the hypoxic microenvironment. Clinical data have demonstrated that overexpressed HIF-1α and HIF-2α in HCC patients are reliable markers of a poor prognosis. Thus, the combination of current sorafenib treatment with gene therapy or inhibitors against HIFs have been documented as promising approaches to overcome sorafenib resistance both in vitro and in vivo. Because the depletion of one HIF-α subunit elevates the expression of the other HIF-α isoform through a compensatory loop, targeting both HIF-1α and HIF-2α would be a more interesting strategy than therapies that discriminate among HIF-α isoforms. In conclusion, there is a marked correlation between the hypoxic microenvironment and sorafenib resistance, suggesting that targeting HIFs is a promising way to increase the efficiency of treatment.

Targeting hypoxia-inducible factors (HIFs), regulatory proteins induced by low oxygen levels, could increase the effectiveness of sorafenib, the only systemic therapy approved for advanced liver cancer. Long-term treatment with sorafenib starves tumors of oxygen, which can lead to the proliferation of cancer cells that are able to survive low oxygen levels. HIFs regulate genes involved in this adaptation and HIF levels are increased in sorafenib-resistant cells. José Mauriz at the University of León, Spain, and colleagues review recent studies on the effects of HIF inhibition on sorafenib efficacy. They conclude that HIF-1α and HIF-2α are predictive markers of sorafenib resistance and that using inhibitors of both these factors as an add-on therapy could improve patient survival. This strategy may be applicable to other types of cancer in which reduced oxygen conditions lead to drug resistance.

Immune consequences of anti-angiogenic therapyin renal cell carcinoma

Current therapies of renal cell carcinoma (RCC), a highly vascularised tumour, mostly rely on anti-angiogenic treatment options. These include tyrosine kinase inhibitors (TKIs) and anti-VEGF monoclonal antibodies. Although these strategies aim at restraining vascularisation to control tumour growth, the effects of such therapies are much wider, as affecting the vessel structure deeply modifies the microenvironment of the tumour mass. The aim of this review is to provide an overview of current knowledge on the global effects of anti-angiogenic treatment, mostly TKIs, on the shaping of the immune component of the RCC microenvironment. The data supporting the modification of immunity by anti-angiogenic therapies are collected to reveal the potential of angiogenesis modulation as a strategy for the adjuvant anti-cancer approach in immunotherapy.