cancers Review Molecular Bases of Drug Resistance in Hepatocellular Carcinoma Jose J.G. Marin 1,2,* , Rocio I.R. Macias 1,2 , Maria J. Monte 1,2 , Marta R. Romero 1,2, Maitane Asensio 1, Anabel Sanchez-Martin 1, Candela Cives-Losada 1, Alvaro G. Temprano 1, Ricardo Espinosa-Escudero 1, Maria Reviejo 1, Laura H. Bohorquez 1 and Oscar Briz 1,2,* 1 Experimental Hepatology and Drug Targeting (HEVEFARM) Group, University of Salamanca, IBSAL, 37007 Salamanca, Spain;
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[email protected] (L.H.B.) 2 Center for the Study of Liver and Gastrointestinal Diseases (CIBERehd), Carlos III National Institute of Health, 28029 Madrid, Spain * Correspondence:
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[email protected] (O.B.); Tel.: +34-663182872 (J.J.G.M.); +34-923294674 (O.B.) Received: 4 June 2020; Accepted: 20 June 2020; Published: 23 June 2020 Abstract: The poor outcome of patients with non-surgically removable advanced hepatocellular carcinoma (HCC), the most frequent type of primary liver cancer, is mainly due to the high refractoriness of this aggressive tumor to classical chemotherapy. Novel pharmacological approaches based on the use of inhibitors of tyrosine kinases (TKIs), mainly sorafenib and regorafenib, have provided only a modest prolongation of the overall survival in these HCC patients.