Structural investigation of erdafitinib, an anticancer drug, with ctDNA: A spectroscopic and computational study

The interaction of drugs with DNA is crucial for understanding their mechanism of action, particularly in the context of gene expression regulation. Erdafitinib (EDB), a pan-FGFR (fibroblast growth factor receptor) inhibitor approved by the FDA, is a potent anticancer agent used primarily in the treatment of urothelial carcinoma. In this study, the binding interaction between EDB and calf thymus DNA (ctDNA) was assessed using molecular docking, UV-absorption spectroscopy, fluorescence spectroscopy, and circular dichroism (CD) spectroscopy. The absorption spectra indicated a hypochromic effect when EDB was combined with ctDNA. The binding constant (K_a) of EDB-ctDNA complex was calculated as 7.84 × 10³ M^-1, corresponds to a free energy change (ΔG) value of approximately -5.06 kcal/mol, indicating a moderate binding affinity. Fluorometric analysis revealed a static binding mechanism in the ground state, with a bimolecular enhancement constant (K_B) of 7.56 × 10¹¹ M^-1. Displacement experiments demonstrated that EDB preferentially binds to the minor groove of ctDNA, with a Ksv value of 5.14 × 10⁴ M^-1. Further, KI quenching and CD spectroscopy confirmed the minor groove binding mode, which was associated with a decrease in the T_m from 68.28 °C to 65.84 °C, reflecting a destabilizing effect on DNA helix. Molecular docking supported these findings, showing that EDB exhibits a strong affinity for the minor groove of ctDNA and hydrogen bonding and Vander Waal interactions are the major forces involved in the binding. These results suggest that EDB primarily binds to the minor groove of ctDNA, which may play a role in its anticancer activity.