P61A6

**P61A6** is a small molecule inhibitor classified as a geranylgeranyltransferase I inhibitor (GGTI), developed for anticancer activity. Its primary mechanism of action is inhibition of protein geranylgeranylation, resulting in decreased membrane association and activation of RhoA, a small GTPase implicated in cell proliferation and tumorigenicity. P61A6 has demonstrated antitumor activity in preclinical models, including inhibition of non-small cell lung cancer and pancreatic cancer cell proliferation, marked G1 cell cycle accumulation, and downregulation of cyclin D1/2. It suppresses tumor growth in xenograft models primarily by reducing cell proliferation rather than direct induction of apoptosis. Key efficacy results include significant suppression of xenograft growth at clinically relevant concentrations, and the effect is largely abrogated in cells expressing geranylgeranylation-bypass mutants of RhoA[1][3].