Antibody targeting to a class I MHC-peptide epitope promotes tumor cell death

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• Therapeutic monoclonal antibodies (mAbs) targeting cell surface tumor antigens are effective cancer treatments.
• Many tumor antigens are intracellular or processed into peptides presented by MHC class I molecules, posing a challenge for traditional mAbs.

Purpose of the Study:

• To develop a novel therapeutic antibody with T cell receptor (TCR)-like specificity for peptide-MHC (pMHC) complexes.
• To evaluate the efficacy of a TCR mimic antibody (TCRm) in targeting and killing cancer cells.

Main Methods:

• Generation of a murine IgG2a mAb (3.2G1) with TCR-like specificity for the peptide-HLA-A*0201 (HLA-A2) complex.
• Assessment of 3.2G1 TCRm binding and specificity using immunofluorescent staining on peptide-loaded cells and human tumor lines.
• Evaluation of 3.2G1 TCRm-mediated cancer cell lysis via complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) in vitro.
• Assessment of in vivo tumor growth inhibition in nude mice.

Main Results:

• The 3.2G1 TCRm specifically recognized the GVL peptide presented by HLA-A2.
• Staining intensity correlated with peptide concentration and cell lysis via CDC.
• The 3.2G1 TCRm recognized endogenously processed peptides and demonstrated high expression on the MDA-MB-231 breast cancer cell line.
• In vitro and in vivo studies showed that 3.2G1 TCRm mediated cancer cell killing and inhibited tumor growth.

Conclusions:

• TCR mimic antibodies represent a promising new class of therapeutic reagents for cancer treatment.
• TCRm can specifically target and induce the lysis of cancer cells by binding to MHC-peptide epitopes.
• The 3.2G1 TCRm validates the potential of TCRm-based therapies for targeting intracellular tumor antigens.