Multispecificity of a recombinant anti-ras monoclonal antibody

Novel affibody molecules as potential agents in molecular imaging for MAGE-A3-positive tumor diagnosis

BACKGROUND

The cancer-testis protein melanoma antigen A3 (MAGE-A3) is highly expressed in a broad range of malignant tumor forms. It has been confirmed that affibody molecules, a novel family of small (∼6.5 kDa) targeting proteins, are useful agents for molecular imaging and targeted tumor treatment. As a novel agent for in vivo molecular imaging detection of MAGE-A3-positive tumors, the efficacy of affibody molecules was assessed in this research.

METHODS

In this study, three cycles of phage display library screening resulted in the isolation of two new affibody molecules (ZMAGE-A3:172 and ZMAGE-A3:770) that attach to MAGE-A3. These molecules were then expressed in bacteria and purified. The affibody molecules with high affinity and specificity were evaluated using western blotting, immunohistochemistry, indirect immunofluorescence, surface plasmon resonance, and near-infrared optical imaging of tumor-bearing nude mice.

RESULTS

The selected ZMAGE-A3 affibodies can precisely bind to the MAGE-A3 protein in living cells and display high-affinity binding to the MAGE-A3 protein at the molecular level. Furthermore, the accumulation of DyLight755-labeled ZMAGE-A3:172 or ZMAGE-A3:770 in MAGE-A3-positive tumors was achieved as early as 30 min and disappeared at 48 h post-injection.

CONCLUSION

Our findings support the potential of the two MAGE-A3 protein-binding affibody molecules for their use as molecular imaging agents.

Antibody Binding Epitope Mapping (AbMap) of Hundred Antibodies in a Single Run

Antibodies play essential roles in both diagnostics and therapeutics. Epitope mapping is essential to understand how an antibody works and to protect intellectual property. Given the millions of antibodies for which epitope information is lacking, there is a need for high-throughput epitope mapping. To address this, we developed a strategy, Antibody binding epitope Mapping (AbMap), by combining a phage displayed peptide library with next-generation sequencing. Using AbMap, profiles of the peptides bound by 202 antibodies were determined in a single test, and linear epitopes were identified for >50% of the antibodies. Using spike protein (S1 and S2)-enriched antibodies from the convalescent serum of one COVID-19 patient as the input, both linear and potentially conformational epitopes of spike protein specific antibodies were identified. We defined peptide-binding profile of an antibody as the binding capacity (BiC). Conceptually, the BiC could serve as a systematic and functional descriptor of any antibody. Requiring at least one order of magnitude less time and money to map linear epitopes than traditional technologies, AbMap allows for high-throughput epitope mapping and creates many possibilities.