As such, the co-administration of these two drugs offers a possible approach to overcoming drug resistance in patients with chronic myelogenous leukaemia (CML). Also, the US FDA has so approved several allosteric medicines. For example, developed by Genzyme ( ), plerixafor is one example of an allosteric blocker of the C-X-C chemokine receptor type 4 (CXCR4) that helps haematopoietic stem cells (HSCs) be mobilised. The debate mentioned above on the benefits of allostery and the proof of successful allosteric drugs underlines the great possibilities of allostery. It is crucial to recognise its constraints, including the unknown positions of allosteric binding sites on target molecules, to overcome the restrictions of allostery.