Exploring a kinase inhibitor targeting PI3KCA mutant cancer cells

The PI3K/mTOR signaling pathway is often disrupted in human cancers, with PI3Kα being one of the most mutated kinases. There has been considerable interest in developing small-molecule inhibitors aimed at blocking the mutant PI3Kα-driven phosphatidylinositol 3-kinase (PI3K) signaling pathway as a potential treatment for cancer. In this study, we describe our effort to identify a compound, phenylacetamide-1H-imidazol-5-one (KIM-161), from our in-house oncogenic kinase-targeting inhibitors. KIM-161 showed excellent anti-proliferative activities at sub-nanomolar concentrations, primarily against mutant PI3Kα breast cancer cell lines, when compared with wild-type PI3Kα breast cancer cell lines, producing both dose- and time-dependent effects with an IC50 range of 1.42 - 0.064 µM. Next, we observed that KIM-161 was able to induce ROS production by modulating breast cancer metabolism, suggesting its broad effects on mutant PI3Kα regulated downstream pathways. We also computationally analyzed the binding interactions between KIM-161 and PI3K-alpha (PDB ID: 8EXL). Molecular docking showed that KIM-161 had a docking score of -7.44 Kcal/mol, compared to the reference compound, which had a docking score of -7.67 Kcal/mol. Moreover, molecular dynamics simulation studies demonstrated that the PI3Ka-KIM-161 complex remained stable throughout the 100 ns simulation, when compared to the PI3Ka complex with the co-crystallized inhibitor. These findings present KIM-161 as a promising lead, providing valuable insights into treatment approaches and resistance mechanisms associated with PI3K inhibitors in specific PIK3CA-mutant cancer subtypes.