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Targeting by affinity-matured recombinant antibody fragments of an angiogenesis associated fibronectin isoform
D Neri1, B Carnemolla, A Nissim
1Cambridge Centre for Protein Engineering-MRC Centre, UK.
Abstract:
The oncofetal fibronectin (B-FN) isoform is present in vessels of neoplastic tissues during angiogenesis but not in mature vessels. B-FN could therefore provide a target for diagnostic imaging and therapy of cancer. Phage display libraries have been used to isolate human antibody fragments with pan-species recognition of this isoform. We describe the use of these fragments in nude mice to target an aggressive tumor (grafted F9 murine teratocarcinoma). Imaging in real time was done by infrared photodetection of a chemically coupled fluorophore. The targeting was improved by use of affinity-matured fragments with low kinetic dissociation rates (koff = 1.5 x 10(-4) s-1) and also by engineering dimeric fragments via a C-terminal amphipathic helix.
Insights
Oncofetal fibronectin (B-FN) shows promise as a cancer imaging and therapy target. Researchers developed antibody fragments that effectively targeted tumors in mice, improving diagnostic and therapeutic strategies.
Area of Science:
- Oncology
- Biotechnology
- Molecular Biology
Background:
- Oncofetal fibronectin (B-FN) is a specific isoform found in tumor blood vessels during angiogenesis.
- B-FN is absent in mature, healthy blood vessels, making it a potential biomarker for cancer.
- Targeting B-FN offers a promising avenue for cancer diagnostics and therapeutics.
Purpose of the Study:
- To isolate human antibody fragments targeting the B-FN isoform using phage display.
- To evaluate the efficacy of these antibody fragments in targeting aggressive tumors in vivo.
- To enhance tumor targeting by affinity maturation and dimerization of antibody fragments.
Main Methods:
- Phage display libraries were employed to select human antibody fragments with pan-species recognition of B-FN.
- The selected fragments were used to target F9 murine teratocarcinoma xenografts in nude mice.
- Real-time imaging was performed using infrared photodetection of a coupled fluorophore.
- Affinity maturation and engineering of dimeric fragments were utilized to improve targeting kinetics.
Main Results:
- Human antibody fragments successfully targeted B-FN in a murine teratocarcinoma model.
- Targeting efficiency was significantly enhanced by using affinity-matured fragments with low dissociation rates (koff = 1.5 x 10(-4) s-1).
- Engineering dimeric fragments further improved the targeting capabilities of the antibody fragments.
Conclusions:
- Antibody fragments targeting oncofetal fibronectin (B-FN) demonstrate significant potential for cancer imaging and therapy.
- Affinity maturation and dimerization are effective strategies for optimizing antibody fragment-based tumor targeting.
- This approach offers a novel method for non-invasive cancer detection and targeted treatment delivery.