The Central Valine Concept Provides an Entry in a New Class of Non Peptide Inhibitors of the P53-MDM2 Interaction

Disrupting the interaction between the p53 tumor suppressor and its regulator MDM2 is a promising therapeutic strategy in anticancer drug research. In our search for non peptide inhibitors of this protein-protein interaction , we have devised a ligand design concept exploiting the central position of Val 93 in the p53 binding pocket of MDM2. The design of molecules based on this concept has allowed us to rapidly identify compounds having a 3-imidazolyl indole core structure as the first representatives of a new class of potent inhibitors of the p53-MDM2 interaction

Tetra-substituted imidazoles as a new class of inhibitors of the p53-MDM2 interaction

Capitalizing on crystal structure information obtained from a previous effort in the search for non peptide inhibitors of the p53-MDM2 interaction, we have discovered another new class of compounds able to disrupt this protein-protein interaction, an important target in oncology drug research. The new inhibitors, based on a tetra-substituted imidazole scaffold, have been optimized to low nanomolar potency in a biochemical assay following a structure-guided approach. An appropriate strategy has allowed us to translate the high biochemical potency achieved in significant anti-proliferative activity on a p53-dependent MDM2 amplified cell line

Comprehensive mapping of p53 pathway alterations in sarcomas reveals an apparent role for MDM2 SNP309 in sarcomagenesis

Re-activation of p53 tumour suppressor activity in diseases such as soft tissue sarcomas is considered an attractive means of targeted therapy. To assess the pattern of mutations affecting the p53 pathway, we have comprehensively mapped mutational events in a panel of 192 bone and soft-tissue sarcomas. These include TP53 and CDKN2A mutational and SNP status, MDM2 and MDM4 amplification and MDM2 SNP309 status. Overall, we found an inverse relationship between MDM2 amplification and TP53 mutations in our samples. Although CDKN2A exon and gene deletions were observed, ARF was found to be predominantly wild-type. Alternatively, a high rate of point mutations in TP53 was observed in leiomyosarcoma and osteosarcoma. Our data show the expected high level of MDM2 amplification in well- and de-differentiated liposarcomas, as well subtype specific patterns. Similarly, MDM4 was amplified in a subtype specific manner. Notably, MDM2 and MDM4 amplification events were found to be frequently associated. We have also analysed the risk allele frequencies for MDM2 SNP309, and show that homozygosity for the G SNP was strongly associated with both liposarcomas and MDM2 amplification. Moreover, our data on a set of tumour-matched normal controls indicates a clear directional progression of the MDM2 SNP309 G allele in tumour samples. In summary, our data suggest that at least 70% of sarcomas sustain some type of genetic alterations in the p53 pathway, of which most impinge on either MDM2 or MDM4. We propose, therefore, that these tumour types should be suitable candidates for trials of MDM2 antagonists