Discovery of Pyrazolopyridine Derivatives as HPK1 Inhibitors

Area of Science:

• Immunology
• Medicinal Chemistry
• Pharmacology

Background:

• Immune checkpoint inhibitors have advanced cancer therapy, but broader treatment options are needed.
• Hematopoietic progenitor kinase 1 (HPK1) negatively regulates T cell receptor signaling, making it a potential therapeutic target.
• Developing selective HPK1 inhibitors could offer new avenues for cancer immunotherapy.

Purpose of the Study:

• To discover and characterize novel pyrazolopyridine derivatives as selective inhibitors of HPK1.
• To identify a lead compound with potent enzymatic and cellular activity and favorable selectivity.
• To evaluate the pharmacokinetic properties of the lead compound in preclinical species.

Main Methods:

• Structure-activity relationship (SAR) studies were conducted to optimize pyrazolopyridine derivatives.
• Enzymatic and cellular assays were used to assess inhibitor potency and selectivity.
• Kinome profiling was performed to evaluate off-target effects.
• Pharmacokinetic studies in rats and monkeys were carried out to assess drug metabolism and distribution.

Main Results:

• A novel series of pyrazolopyridine derivatives targeting HPK1 was identified.
• Compound 16 emerged as a potent and selective HPK1 inhibitor with strong enzymatic and cellular activity.
• Compound 16 exhibited encouraging kinome selectivity, minimizing off-target effects.
• Compound 16 demonstrated favorable pharmacokinetic profiles in rat and monkey models.

Conclusions:

• Novel pyrazolopyridine derivatives are effective inhibitors of HPK1.
• Compound 16 represents a promising drug candidate for further development in cancer immunotherapy.
• The favorable pharmacokinetic properties of compound 16 support its advancement into preclinical efficacy and safety studies.