Tyrosine kinase inhibitors: A potential approach to the treatment of hepatocellular carcinoma

The increasing number of patients with hepatocellular carcinoma (HCC) and the highly unfavourable prognosis of the disease are two important reasons why more effort needs to be devoted to investigating other therapies able to block or reduce tumor progression and cancer metastasis. The underlying cirrhosis on which HCC develops limits the use of common chemotherapies, mainly because of their toxicity. Recently, great attention has been paid to a family of molecules that inhibits the tyrosine kinase (TK) receptors, because of their relevant role in activating intracellular pathways responsible for several biological activities of the HCC cells. In particular, proliferation, invasion, survival, apoptosis, are regulated by Erk 1/2 and Akt pathways, that can be considered for this reason as potential therapeutic targets. Therefore, the idea is to fight HCC by blocking the molecular mechanisms exploited by the cancer to develop and to metastasize. The epithelial growth factor and the vascular endothelial growth factor receptors (EGFR and VEGFR, respectively) have been identified as the major targets for these new therapies. In this review the biological role of both growth factors in HCC will be discussed, together with the use of anti-EGFR and anti-VEGFR. The preliminary results obtained in vitro or in "in vivo" experimental models have been very promising, whereas the few studies conducted in patients have been not comparably satisfactory. This could be because of the limited number of patients and of their advanced stage of HCC, nevertheless the possibilities of using this family of drugs should be further explored, together with aspects contributing to a better understanding of the molecular mechanisms driving HCC progression.