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Fascin is a major actin‐binding protein (ABP) in filopodia and is highly expressed in metastatic tumors. To inhibit its function, a potent inhibitor called NP‐G2‐044 is currently in phase II clinical trials. However, the binding mode of this inhibitor remains unclear. In this study, the binding mode of NP‐G2‐044 in fascin and predicted drug resistance mutations is investigated. The rough binding position and pose can be deduce based on information from its derivant NP‐G2‐029, whose crystal structure with fascin has been solved. Molecular docking, free energy perturbation (FEP) simulation and metadynamics simulation are performed to confirm the binding pose. Based on the molecular docking results, two binding modes of NP‐G2‐044, pose A and B, are obtained, with pose A being more favorable. For pose A, the planar indazole moiety has the same orientation as NP‐G2‐029 in the complex with fascin, while for pose B, it rotates ≈90°. FEP and metadynamics simulations indicate that both binding poses are possible. Relative binding free energies for mutation effects calculated by FEP predict E215A and R217A are drug resistance mutations. These findings are important for further drug development targeting fascin. [ABSTRACT FROM AUTHOR]