The underlying hypothesis of the synergistic activity of octreotide and everolimus is based on the combination of a) a direct action of everolimus over mTOR (mammalian target of rapamycin), and b) the inhibitory effect of octreotide on the IGF-I (insulin like growth factor 1) system preventing the activation of the mTOR system by this factor. Both types of inhibition would completely cancel this signal transduction pathway, which is so important in neuroendocrine tumours.