Tumor suppressor protein p53 is mutated in close to 50% of human tumors. Under steady state conditions, the two E3 ligases MDM2 and MDM4 interact with and inhibit the transcriptional activity of p53. Inhibition of p53-MDM2/4 interaction to reactivate p53 has therefore been considered a therapeutic strategy. In this study, we tested p53-MDM2 protein-protein interaction inhibition using the small molecule AMG 232, which is currently being tested in phase 1b/2a clinical trials. In vitro, AMG 232 induced a significant, p53-dependent growth arrest in the mouse melanoma cell line B16-F10. Using mass spectrometry-based proteomics, we identified differential protein expression patterns following AMG 232 treatment of B16-F10 melanoma cells. In vivo, the growth of B16-F10 melanoma cells implanted in WT C57BL/6 mice was significantly reduced by AMG 232 treatment. Our data demonstrate that AMG 232 induces a p53-dependent tumor growth arrest in an immunocompetent mouse model, and we are currently testing whether AMG232 can synergize with checkpoint immunotherapy.

Citation Format: Katrine Ingelshed, Danai Lianoudaki, Dilraj Lama, Silke Sohn, Nicolas Fritz, Long Jiang, Fredrik Wermeling, Mikael Karlsson, David P. Lane, Saikiran K. Sedimbi. Inhibition of p53-MDM2 protein interaction reduces tumor growth in a mouse melanoma model [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A79.