An orally bioavailable human double minute 2 homolog (HDM2) inhibitor with potential antineoplastic activity. Siremadlin inhibits the binding of the HDM2 protein to the transcriptional activation domain of the tumor suppressor protein p53. By preventing this HDM2-p53 interaction, the proteasome-mediated enzymatic degradation of p53 is inhibited, which may result in the restoration of both p53 signaling and p53-mediated induction of tumor cell apoptosis. HDM2, a zinc finger protein and negative regulator of the p53 pathway, is often overexpressed in cancer cells and has been implicated in cancer cell proliferation and survival.