Rain Oncology Inc. is a late-stage precision oncology company. The Company is focused on developing therapies that target oncogenic drivers to genetically select patients. Its product candidate includes milademetan. Milademetan is an oral, small molecule inhibitor of the p53-mouse double minute 2 (p53-MDM2) complex that reactivates p53. The product candidate is being developed in patients with MDM2-dependent cancers. p53 acts as a regulator of various cellular processes. The activity of p53 is controlled and regulated by the inhibitory protein MDM2. MDM2 binds to p53, thereby inducing degradation and allowing normal cells to function properly. Milademetan, by binding MDM2 at the p53 interaction site, prevents the formation of the MDM2-p53 complex, allowing p53 reactivation and subsequent transcription of genes that trigger cancer cell cycle arrest or apoptosis and can be readily measured by increases in the pharmacodynamic marker MIC-1 (GDF15) in the blood.