Thermodynamics and mechanism of afatinib-EGFR binding through a QM/MM approach

Area of Science:

• Computational chemistry
• Molecular dynamics
• Structural biology

Background:

• Afatinib is a tyrosine kinase inhibitor targeting the epidermal growth factor receptor (EGFR).
• EGFR is implicated in non-small cell lung cancer (NSCLC) development.
• Accurate computation of drug-target binding energy is vital for drug discovery.

Purpose of the Study:

• To compute thermodynamic interaction parameters between afatinib and EGFR.
• To compare binding free energy calculations using Normal Mode Analysis (NMA), Interaction Entropy (IE), and C2 methods.
• To evaluate the accuracy of MM/PBSA in predicting binding energies.

Main Methods:

• Molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) simulations.
• Normal Mode Analysis (NMA).
• Interaction Entropy (IE) and C2 computational methods.

Main Results:

• MM/PBSA predicted a binding free energy of -19.86 kcal mol⁻¹ for the hydrated complex, closely matching experimental values (~ -13.00 kcal mol⁻¹).
• IE and C2 methods yielded significantly different values (-32.96 and -35.47 kcal mol⁻¹, respectively).
• MM/PBSA showed a low standard deviation (σ_IE = 3.54 kcal mol⁻¹), indicating binding entropy convergence.

Conclusions:

• MM/PBSA provides a more accurate estimation of afatinib-EGFR binding free energy compared to IE and C2 methods.
• Accurate computational methods are essential for advancing covalent drug discovery in cancer treatment.
• Further advancements in structural biology and simulation techniques are needed for complex drug discovery challenges.