Specific targeting of a naturally presented osteosarcoma antigen, papillomavirus binding factor peptide, using an...

Area of Science:

• Oncology
• Immunology
• Biotechnology

Background:

• Osteosarcoma is a rare, aggressive cancer primarily affecting adolescents, with poor outcomes for chemotherapy non-responders.
• Existing treatments necessitate new modalities, particularly peptide-based immunotherapies targeting specific tumor antigens.
• Previous work identified the papillomavirus binding factor (PBF) antigen and its T-cell epitope (PBF A2.2) presented by HLA-A2.

Purpose of the Study:

• To develop a method for detecting the HLA-A2·PBF A2.2 complex on osteosarcoma cells for immunotherapy selection.
• To generate a specific antibody probe for the HLA-A*02:01·PBF A2.2 complex.

Main Methods:

• Utilized a naive single chain variable fragment (scFv) phage display library to isolate antibodies against the HLA-A*02:01·PBF A2.2 complex.
• Screened and characterized scFv clones for binding affinity and specificity to the target complex.
• Validated the antibody's reactivity with peptide-pulsed cells and osteosarcoma cell lines expressing HLA-A2 and PBF.

Main Results:

• Successfully isolated a high-affinity scFv antibody, designated clone D12 (KD = 1.53 × 10(-9) M).
• Demonstrated that D12 specifically binds to the HLA-A2·PBF A2.2 complex.
• Confirmed the expression of the HLA·peptide complex on osteosarcoma cells using the D12 antibody.

Conclusions:

• The isolated scFv clone D12 is a valuable tool for detecting the HLA-A2·PBF A2.2 complex on osteosarcoma cells.
• D12 can aid in selecting patients eligible for PBF A2.2 peptide-based immunotherapy.
• This antibody may facilitate the development of novel antibody-based immunotherapies for osteosarcoma.