TABLE 1.
Comparison between antibody and affibody as a targeting ligand
Antibody | Affibody | |
---|---|---|
Structure | Intact IgG monoclonal antibody | Small peptide chain |
Size | Large size around 150 kDa | Small size around 6.5 kDa [43] |
Affinity & specificity | Strong | Strong [43] |
Heat stability | Poor | Stable |
Manufacturing process | Difficult process | Easy process |
Production | In vivo depending on the immune system | In vitro by chemical synthesis or by inexpensive bacterial production [44] (Originally IgG-binding, Z domain derived from staphylococcal surface protein A). |
Cost | Costly | Not costly |
Immunogenicity | The early produced murine antibodies generated human anti-mouse antibody (HAMA) response. After which the production of humanized monoclonal antibodies has been significantly decreasing the immunogenic reactions such as anaphylactic shock. However, some humanized antibodies still carry immunological risk [45] | Non-immunogenic [46] |
Clearance | Long circularity time | Rapid clearance of unbound trace due to its small size [47] |
Imaging properties | - Acceptable imaging contrast - Analysis few days after injection - Acceptable tumor penetration - Compatible with variable detection method. |
- Strong imaging contrast - Analysis few hours after injection - Better tumor penetration due to small size and enhanced EPR effect. - Minimal background and interference. - Compatible with variable detection method [47] |
Examples | - Pertuzumab: anti HER2+ antibody - Ofatumumab: anti-CD20 |
- ABY-035: anti-IL-17 - HEHEHE-Z08698-NOTA: anti-HER3 affibody |