Lomitapide as a Potential Estrogen Receptor Inhibitor: A Computational Drug Repurposing Study

Objective: Estrogen receptor (ER) inhibitors have significant therapeutic potential for hormone-dependent cancers and related disorders. Tamoxifen, a well-known selective estrogen receptor modulator, has been widely used as adjuvant therapy for estrogen receptor-positive breast cancer. However, tamoxifen may exhibit a tendency to develop resistance with prolonged usage and particularly elevate the risk of uterine cancer. Therefore, there is a need for the discovery and development of new ER modulators or inhibitors. In this study, we identified potential estrogen receptor inhibitors through computational drug repositioning. Methods: A set of 2048 compounds, encompassing FDA-approved drugs and active metabolites, were subjected to molecular docking, molecular dynamics simulations, and free energy calculations to evaluate their interaction with estrogen receptor α (ERα). Results: Among the compounds evaluated, conivaptan, atogepant, and lomitapide exhibited the highest affinities for ERα. Lomitapide displayed a superior docking score (-12 kcal/mol) compared to the established ER inhibitor, tamoxifen (-10 kcal/mol). Further investigation using molecular dynamics simulations and free energy calculations disclosed lomitapide's heightened binding affinity of -380.727 kJ/mol, surpassing tamoxifen's binding affinity of -352.029 kJ/mol. Conclusion: This comprehensive computational exploration underscores lomitapide's potential as a compelling candidate with an envisaged stronger estrogen receptor affinity than the acknowledged standard, tamoxifen. To validate lomitapide's promise as a novel ER inhibitor, essential in vitro and in vivo studies are suggested. These investigations will provide essential insights into lomitapide's reposition in addressing the challenges tied to hormone-dependent cancers and associated maladies.