Small molecules targeting the PD-1/PD-L1 axis for cancer immunotherapy.

Area of Science:

• Immunology
• Oncology
• Drug Discovery

Background:

• The PD-1/PD-L1 pathway is a critical immune checkpoint that promotes tumor immune evasion by inducing T-cell exhaustion.
• Approved anti-PD-1/PD-L1 monoclonal antibodies (mAbs) face challenges including high cost, poor oral bioavailability, and immunogenicity.
• These limitations drive research towards developing small molecule therapeutics targeting the PD-1/PD-L1 pathway.

Purpose of the Study:

• To review the structure and function of the PD-1/PD-L1 pathway.
• To summarize emerging classes of small molecule inhibitors and degraders targeting PD-1/PD-L1.
• To provide insights into the development of safe and effective small molecule immunotherapeutics for cancer.

Main Methods:

• Literature review focusing on PD-1/PD-L1 pathway signaling.
• Analysis of small molecule inhibitors that induce PD-L1 dimerization or block PD-1/PD-L1 binding.
• Examination of PD-L1 degraders, including Proteolysis-targeting chimeras (PROTACs) and Lysosome-targeting chimeras (LYTACs).
• Review of dual-target inhibitors for synergistic therapeutic effects.

Main Results:

• Small molecule inhibitors can block PD-1/PD-L1 binding or induce PD-L1 dimerization.
• Novel degradation strategies (PROTACs, LYTACs) offer new avenues for targeting PD-L1.
• Dual-target inhibitors show potential for enhanced therapeutic efficacy.
• Small molecules present advantages like oral bioavailability and reduced immunogenicity compared to mAbs.

Conclusions:

• Small molecules represent a promising alternative to monoclonal antibodies for PD-1/PD-L1 targeted cancer immunotherapy.
• Challenges such as drug resistance and toxicity require further investigation and mitigation strategies.
• Continued research into novel small molecule designs is crucial for advancing antitumor immunotherapy.