Finding the Right Heavy Chains for Immunostimulatory Antibodies

Area of Science:

• Immunology
• Oncology
• Pharmacology

Background:

• Immune checkpoint inhibitors have transformed oncology over the last decade.
• These antibodies are a heterogeneous group with varied mechanisms of action.
• Antibody function depends on the target, target-expressing cells, and IgG subclass/variant.

Purpose of the Study:

• To dissect the complex landscape of immune checkpoint antibodies.
• To differentiate antibodies based on their targets and mechanisms.
• To highlight the importance of heavy chain isotypes in antibody efficacy.

Main Methods:

• Clinical experience analysis.
• Precise analysis of heavy chain isotypes using new Ge nomenclature.
• Categorization of antibodies based on target (inhibitory receptors vs. ligands) and function (antagonistic vs. agonistic).

Main Results:

• Anti-CTLA-4 antibodies primarily kill regulatory T cells.
• Anti-PD-1 antibodies act as true antagonistic antibodies.
• Antibodies targeting PD-L1 and CD47 have distinct mechanisms due to tumor antigen expression and potential killing effects.
• Agonistic antibodies targeting CD40 or 4-1BB are in earlier stages of development.

Conclusions:

• Immune checkpoint antibodies exhibit diverse mechanisms of action.
• Heavy chain isotype selection is critical for achieving the intended pharmacological effect.
• Understanding these distinctions is vital for optimizing cancer immunotherapy.