Abstract Restoring p53 levels through disruption of p53–MDM2 interaction has been proved to be a valuable approach in fighting cancer. We herein report the synthesis and evaluation of eighteen spiroisoxazoline oxindoles derivatives as p53–MDM2 interaction inhibitors. Seven compounds showed an antiproliferative profile superior to the p53–MDM2 interaction inhibitor nutlin-3, and induced cell death by apoptosis. Moreover, proof-of-concept was ...