Theoretical Studies on Selectivity of HPK1/JAK1 Inhibitors by Molecular Dynamics Simulations and Free Energy...

Area of Science:

• Biochemistry
• Immunology
• Computational Chemistry

Background:

• Hematopoietic progenitor kinase 1 (HPK1) negatively regulates T cell receptors, making it a target for cancer immunotherapy.
• High-throughput screening has identified HPK1 inhibitors, but off-target effects on kinases like JAK1 can cause toxicity.
• Developing selective HPK1 inhibitors is essential for safe and effective immunotherapies.

Purpose of the Study:

• To investigate the molecular mechanisms underlying the selectivity of indazole-based HPK1 inhibitors against JAK1.
• To elucidate the structural basis for selective inhibition of HPK1 over JAK1 using computational approaches.

Main Methods:

• Conventional molecular dynamics (MD) simulations.
• Binding free energy calculations.
• Umbrella sampling simulations.

Main Results:

• Computational methods revealed distinct binding interactions between indazole inhibitors and HPK1 versus JAK1.
• A specific salt bridge interaction between the inhibitor and Asp101 in HPK1 was identified as a key determinant of selectivity.
• This salt bridge interaction was absent or significantly weaker in the context of JAK1 inhibition.

Conclusions:

• The salt bridge interaction with Asp101 is critical for achieving selectivity of indazole compounds towards HPK1 over JAK1.
• Understanding this mechanism can guide the rational design of more potent and selective HPK1 inhibitors.
• This research provides a foundation for developing safer and more effective immunotherapies targeting HPK1.