MDM2 and sarcoma: MDM2-amplification and TP53 mutation are widely and consistently reported as mutually exclusive, so that the selection for TP53 mutation in the context of MDM2 amplification represents a novel genotype that may occur in therapeutic situations, particularly with those cancers in which MDM2-amplification is prevalent, such as sarcomas, against which MDM2 inhibitors have demonstrated activity in clinical trials.