Arghavan Golbaz Hagh, Martina Jones, Simon Puttick, Chris Howard, Stephen Rose, Andrew Whittaker, Stephen Mahler*


Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia Queensland, 4072, Australia


Primary brain tumors account for 1-2% of all diagnosed cancers in Australian adults and 9% of all cancers in Australian young people1. Despite many advances in brain cancer treatments, the prognosis remains poor with median survival rates of less than 15 months2. Many biochemical and biological pathways involved in cancer development and progression have been revealed by mouse models however, these models fail to reproduce many of complex features of human cancers. Domestic dogs with naturally occurring cancers are without many of the limitations found in murine models and could be counted as a transition model between human and mouse3. Research has actively focused on testing new therapeutic approaches, including theranostics. Antibodies are very attractive potential theranostics agents as they are highly specific and easily functionalized4. It has been shown that the EphA2 receptor tyrosine kinase (RTK) is overexpressed in a number of tumours, including glioblastoma5. The expression level of Eph RTK has not only been linked to tumour progression, but also to metastasis and poor patient prognosis5. We hypothesise that an antibody that cross-reacts with both canine and human EphA2 will enable comparative oncology trials in dogs with naturally occurring brain tumours to evaluate EphA2 as a theranostic target, followed by direct translation into human studies. Single chain Fv (scFv) antibody fragments of defined specificity may be isolated from antibody gene libraries displayed on the surface of bacteriophage (phage display), combined with iterative rounds of antigen-driven selection and phage proliferation6.
In this project the extracellular domain of human and canine EphA2 were separately cloned and expressed. Then, the identity of purified canine and human EphA2-ECD was confirmed by peptide mass fingerprint spectrometry. The ECDs of canine and human EphA2 were subsequently used for separate phage display panning experiments to obtain scFv binders against canine and human EphA2. Phage particles obtained after each round of panning were tested using an ELISA assay to determine the enrichment for binders to each EphA2-ECD. Monoclonal phage antibody ELISA was performed to isolate individual phage clones. Sequence alignment of individual clones showed that one particular clone (named AGH001) was isolated from both the human and canine EphA2 biopanning strategies. This scFv showed cross reactivity against human and canine EphA2. The isolated scFv light and heavy chain sequences were cloned into human and canine constant region backbone vectors, and expressed as whole IgG antibodies. The purified mAbs will be labelled for diagnostic imaging, followed by in vivo targeting assays in mouse xenograft models.

1Cancer in Australia. Australian Institute of Health and Welfare 2017, 9101.
2Anton, K et al. Hematology/oncology clinics of North America 2012, 26(4), 825-53.
3Paoloni, M and Khanna C. Nature Reviews Cancer 2008, 8(2),147-56. Translation of new cancer treatments from pet dogs to humans.
4 Fleuren, E.D. et al. Molecular Oncology 2014, 8(4), 799-812.
5 Wykosky, J. et al. Molecular Cancer Research 2005, 3(10), 541-51.
6 Christoph, M.H and John, R.S. Journal of investigative Dermatology 2013, 134. Antibody Phage Display: Technique and Applications.
Name: Mrs Arghavan Golbaz Hagh
Research interests: Brain cancer, Molecular imaging, Engineering of monoclonal antibodies.