Novel toll-like receptor 2 ligands for targeted pancreatic cancer imaging and immunotherapy

Area of Science:

• Immunology
• Oncology
• Medicinal Chemistry

Background:

• Toll-like receptor 2 (TLR2) is a key target for immune stimulation in cancer immunotherapy.
• TLR2 serves as a cell-surface marker for pancreatic cancer, presenting an opportunity for targeted therapies.
• Development of novel synthetic agonists is crucial for advancing cancer imaging and therapeutic strategies.

Purpose of the Study:

• To design, synthesize, and characterize novel, high-affinity TLR2 agonists for potential cancer applications.
• To evaluate the immune-stimulating properties of synthesized compounds as potential cancer immunotherapy adjuvants.
• To develop a targeted imaging agent for TLR2-expressing pancreatic tumors using a fluorescently labeled agonist.

Main Methods:

• Synthesis and characterization of 13 novel, fully synthetic TLR2 agonists.
• Evaluation of agonist activity using NF-κB functional assays and binding affinity via competitive binding assays.
• In vivo assessment of immune adjuvant potential and in vivo tumor targeting and imaging using a near-infrared dye conjugate.

Main Results:

• Analogue 10 exhibited the highest agonist activity (EC(50) = 20 nM) and binding affinity (K(i) = 25 nM).
• Compound 10 demonstrated in vivo immune stimulation, promoting antigen-specific CD8+ T cell generation, indicating potential as an immunotherapy adjuvant.
• The fluorescent conjugate, compound 13, retained high agonist activity (EC(50) = 34 nM) and binding affinity (K(i) = 11 nM), and successfully visualized TLR2-expressing pancreatic tumor xenografts in vivo with demonstrated selectivity.

Conclusions:

• Novel synthetic TLR2 agonists were successfully developed, with compound 10 showing significant potential for cancer immunotherapy.
• The fluorescently labeled compound 13 serves as a selective imaging agent for TLR2-positive pancreatic tumors.
• These findings support the development of TLR2-targeted agents for combined cancer imaging and immunotherapy.