Discovery and Optimization of Pyrazine Carboxamide AZ3246, a Selective HPK1 Inhibitor.

Area of Science:

• Immunology
• Pharmacology
• Drug Discovery

Background:

• Hematopoietic progenitor kinase 1 (HPK1) negatively regulates T cell receptor signaling.
• Nonselective HPK1 inhibitors risk off-target effects on T cell activation.
• Targeting HPK1 is a strategy for enhancing anti-tumor immunity in immuno-oncology.

Purpose of the Study:

• To discover and optimize selective HPK1 inhibitors.
• To develop a compound that enhances T cell activity without inhibiting other kinases.
• To evaluate the therapeutic potential of a novel selective HPK1 inhibitor.

Main Methods:

• Structure-based drug design was employed to optimize pyrazine carboxamide inhibitors.
• Compound 24 (AZ3246) was synthesized and characterized.
• In vitro assays measured IL-2 secretion and kinase inhibition. In vivo studies assessed pharmacokinetic properties and anti-tumor activity in a syngeneic mouse model.

Main Results:

• A highly selective HPK1 inhibitor, compound 24 (AZ3246), was identified.
• Compound 24 induced IL-2 secretion in T cells with an EC50 of 90 nM.
• The compound demonstrated favorable pharmacokinetics for oral administration and significant anti-tumor activity in the EMT6 model.

Conclusions:

• Selective inhibition of HPK1 is achievable and therapeutically relevant.
• Compound 24 represents a promising candidate for immuno-oncology therapies.
• This selective inhibitor enhances T cell function and exhibits anti-tumor efficacy.