ARI-3996

**ARI-3996** is a tumor-activated prodrug designed to deliver a bortezomib-like proteasome inhibitor selectively to solid tumors expressing fibroblast activation protein (FAP). Upon activation by FAP, which is abundant in the tumor stroma of many epithelial cancers but minimal in healthy tissues, ARI-3996 releases its cytotoxic payload to inhibit the proteasome, inducing cell cycle arrest and apoptosis in tumor cells. This approach aims to replicate bortezomib's efficacy in multiple myeloma while minimizing dose-limiting toxicities like peripheral neuropathy and thrombocytopenia seen in solid tumors, potentially enabling safer combination with chemotherapy. Developed by Arisaph Pharmaceuticals through NIH-funded STTR programs, it has shown proof-of-concept in preclinical models with reduced systemic toxicity compared to bortezomib.[1][3][9][13]