The efficacy of classical and molecular therapies in cancer is hampered by the occurrence of primary (intrinsic)
and secondary (acquired) refractoriness of tumours to selected therapeutic regimens. Nevertheless, the increased knowledge
of the genetic, molecular and metabolic mechanisms underlying cancer results in the generation of a correspondingly
increasing number of druggable targets and molecular drugs. Thus, a current challenge in molecular oncology and medicinal
chemistry is to cope with the increased need for modelling, both in cellular and animal systems, the genetic assets associated
to cancer resistance to drugs. In this review, we summarize the current strategies for generation and analysis of in
vitro and in vivo models, which may reveal useful to extract information on the molecular basis of intrinsic and acquired
resistance to anticancer molecular agents.