A New B7:CD28 Family Checkpoint Target for Cancer Immunotherapy: HHLA2

Area of Science:

• Immunology
• Molecular Biology
• Oncology

Background:

• The B7 family of immune checkpoint proteins plays a critical role in regulating T-cell responses.
• HHLA2 (Human cell surface antigen HHLA2) is a recently discovered B7 family member with incompletely understood functions.
• Understanding HHLA2's interactions is crucial for developing novel immunotherapies.

Purpose of the Study:

• To elucidate the function of HHLA2 in T-cell modulation.
• To identify the receptors that mediate HHLA2's effects on T-cells.
• To assess HHLA2's potential as a therapeutic target in cancer immunotherapy.

Main Methods:

• Analysis of HHLA2 expression in various human cancers.
• In vitro studies investigating HHLA2 interactions with T-cells and potential receptors (e.g., TMIGD2).
• Functional assays to determine coinhibitory or costimulatory effects of HHLA2 on T-cell activation.

Main Results:

• HHLA2 was found to be expressed on a range of human cancers.
• Evidence suggests HHLA2 interacts with TMIGD2 and potentially another receptor to modulate T-cell function.
• Conflicting results were observed, with two studies indicating coinhibition and one suggesting costimulation.

Conclusions:

• HHLA2 is a promising target for cancer immunotherapy due to its expression on tumors and its T-cell modulatory functions.
• Further research is needed to fully characterize HHLA2's dual role (coinhibitory/costimulatory) and its precise mechanisms of action.
• Targeting HHLA2 could offer a novel strategy to enhance anti-cancer immunity.