In the case of the realization of the importance of the IGF system in cancer, the biological relevance of some of its family components, namely the IGF1R as the supposed sole mediator of the IGF-I and IGF-II effects, came early in the drug industry game, although experimental data related to atypical variants [92,93] and hybrid receptors with its related cousin, the insulin receptor (IR) [94,95,96], were already known. Here, IGF1 is linked to cancer.