The tiny tool to fight big diseases


Fragment antibodies, as the name suggests, are fragments of the binding end of a monoclonal antibody (mAb) and can be a small but mighty tool to fight disease. While mAbs range from around 150kDa in size, fragment antibodies as small as 3kDa have been used in various applications.

Their small size helps access difficult-to-reach therapeutic targets on tissues and cells as well as penetrate tumours more effectively.1,2 These small fragments can also be useful for rapidly blocking signalling molecules or receptors. Because they do not have the bulk of a whole antibody, fragments can also minimise other downstream effects on the immune system.1

Fragment antibodies are emerging as great tools in imaging and diagnostics because they are capable of detecting cellular proteins with high affinity and specificity. They can be easily linked to radioisotopes, fluorescent molecules or enzymes that tag specific biomarkers in patients. They also have a shorter half-life in the body which results in faster clearance and may result in fewer risks of side effects from potentially invasive diagnostic agents.

Fragment antibodies can also be produced in simpler steps compared with more complex antibodies, making them potentially faster to produce in high yields.


At AstraZeneca, we are developing a robust protein expression toolbox specifically for the design and development of fragment antibodies that can potentially have therapeutic benefits.

Herren Wu Senior Vice President, Antibody Discovery and Protein Engineering, R&D

References

1. Bates, Adam, and Christine A. Power. 2019. “David vs. Goliath: The Structure, Function, and Clinical Prospects of Antibody Fragments.” Antibodies (Basel, Switzerland) 8 (2). https://doi.org/10.3390/antib8020028.

2. Kholodenko, Roman V., Daniel V. Kalinovsky, Igor I. Doronin, Eugene D. Ponomarev, and Irina V. Kholodenko. 2019. “Antibody Fragments as Potential Biopharmaceuticals for Cancer Therapy: Success and Limitations.” Current Medicinal Chemistry 26 (3): 396–426.



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