TPI-1 is a potent and selective inhibitor of Tankyrases (TNKS1 and TNKS2), which are poly(ADP-ribose) polymerases (PARPs) involved in the Wnt/β-catenin signaling pathway. Its primary application lies in cancer research, particularly in targeting cancers driven by aberrant Wnt signaling, such as colorectal and gastric cancers. By inhibiting tankyrases, TPI-1 stabilizes the AXIN complex, leading to increased degradation of β-catenin and suppression of downstream oncogenic transcription. This makes TPI-1 a valuable tool compound for studying pathway dynamics and evaluating therapeutic strategies in preclinical models. It is also used in combination studies with other targeted agents to overcome resistance mechanisms in tumor cells. Due to its cell permeability and specificity, TPI-1 is widely employed in cellular and biochemical assays to probe tankyrase function and assess antiproliferative effects in various cancer cell lines.