RESEARCH & DEVELOPMENT
VarCT Diagnostics’ core technology is a proprietary recombinant version of the malarial VAR2CSA protein (rVAR2), which binds specifically and with a high affinity to oncofetal chondroitin sulfate A (ofCS) – a distinct carbohydrate found on a wide range of proteoglycans redundantly expressed in most types of cancer.
VarCT Diagnostics aims to use the unique binding properties of rVAR2 to develop novel assays to detect and diagnose various types of cancer. Our vision is that these assays should become the leading method to screen and diagnose most types of cancers at an early stage, significantly improving treatment outcome.
Patents covering the use of rVAR2 and ofCS for cancer diagnostics have been issued in the all major markets.
Current R&D programs
The focus of VarCT Diagnostics’ development activities is on producing reliable methods to detect and capture circulating tumor cells. I addition, we are developing methods to quantify free ofCS in plasma or other fluids. As ofCS is also expressed on circulating fetal cells, the assays developed for CTC capturing are being re-purposed for prenatal diagnostic applications.
Our R&D programs are being developed as internal projects and together with academic as well as commercial partners. The current research portfolio is illustrated below.
The core technology: Using a malaria protein to identify and capture Circulating Tumor Cells (CTCs)
VarCT Diagnostics’s technology is founded on an innovative amalgamation of malaria parasitology and cancer research discoveries. A key feature of malaria pathogenesis is the ability of parasites to invade and multiply in red blood cells. As parasite-infected red blood cells (IRBCs) are susceptible to filtration and destruction in the speen, the parasites express proteins on the cell surface of IRBCs that mediates sequestration in different tissues of the human host. One such protein, VAR2CSA tethers IRBCs specifically to the placenta via a high-affinity interaction to a distinct type of chondroitin sulfate A, named oncofetal CSA (ofCS). By catching growth factors and promoting cell motility, ofCS ensures that the placenta can grow fast, establish blood supply, and invade the uterine tissue. Fast growth and invasiveness are features shared between solid tumors and the placenta.
Recent research has confirmed that expression of ofCS indeed is a common molecular modification to proteoglycans found exclusively in placenta and most human solid tumors. It has been demonstrated that VAR2 Pharmaceuticals recombinant VAR2CSA protein (rVAR2) binds to tumor cells of epithelial and mesenchymal origin, including epithelial tumor cells that have undergone epithelial- to mesenchymal transition. The ofCS modification has not been detected on any normal cell type investigated to date, which creates an attractive opportunity for rVAR2-based cancer diagnostics, such as detection and capturing of circulating tumour cells (CTCs), as well as other diagnostic applications based on detection of ofCS-modified proteoglycans
The cancer-specific ofCS modification can also be utilized for targeting of anti-cancer drugs, a concept that is explored by VAR2 Pharmaceuticals. A recombinant form of VAR2CSA, rVAR2, is used as the backbone for development of both therapeutic and diagnostic products. Our proprietary rVAR2 proteins bind with high affinity and specificity to ofCS, which are utilized to develop technology for enrichment of CTCs from cancer patient blood samples. The rVAR2 technology enables binding of CTCs that are negative for the current gold standard CTC marker EpCAM, and is able to detect and capture CTCs with a mesenchymal profile. As such, rVAR2-based CTC isolation holds promise to become a broadly applicable assay for early screening and detection of cancer in liquid biopsies, which may be able to guide treatment decisions in the clinic.
Cancer and liquid biopsy
Despite significant advances in the treatment of cancer over the past decades, the number of people dying of malignant diseases reached 8.2 million globally in 2012 (latest data from the World Health Organisation) and is expected to increase in the future.
It is well-known that the chance of surviving cancer is better when the disease is detected early and therefore new diagnostic methods enabling early diagnosis are in demand. Many attempts have been made to develop simple and minimally invasive methods for cancer diagnosis, by analyzing relevant biomarkers in the blood or other body fluids (liquid biopsy). Such methods could potentially enable earlier diagnosis of cancer, or even be applied for screening people at risk of developing cancer, in a cost-effective way. Such methods might also be applied for cancer disease surveillance purposes after treatment.
The two main liquid biopsy approaches in development are sequencing of circulating tumour DNA and isolation and analysis of CTCs. The two approaches have their unique merits and are likely to be complementary strategies in future cancer diagnosis. Other strategies for utilizing VAR2 technology in liquid biopsies are also under development.
The VAR2CSA malaria protein efficiently retrieves circulating tumor cells in an Ep-CAM-independent manner. Agerbæk M. Ø., Bang-Christensen S. R., Ming-Hsin Yang, Clausen T. M., Pereira M. A., Sharma S., Ditlev S. B., Nielsen M. A., Choudhary S., Gustavsson T., Sorensen P. H., Meyer T., Propper D., Shamash J., Theander T. G., Aicher A., Daugaard M., Heeschen C., and Salanti A. Nature Communications, 9, Article number: 3279, 2018 (DOI: 10.1038/s41467-018-05793-2).
Targeting Human Cancer by a Glycosaminoglycan Binding Malaria Protein. Salanti A, Clausen TM, Agerbæk MØ, Al Nakouzi N, Dahlbäck M, Oo HZ, Lee S, Gustavsson T, Rich JR, Hedberg BJ, Mao Y, Barington L, Pereira MA, LoBello J, Endo M, Fazli L, Soden J, Wang CK, Sander AF, Dagil R, Thrane S, Holst PJ, Meng L, Favero F, Weiss GJ, Nielsen MA, Freeth J, Nielsen TO, Zaia J, Tran NL, Trent J, Babcook JS, Theander TG, Sorensen PH, Daugaard M. Cancer Cell. 2015 Oct 12;28(4):500-14.
Oncofetal Chondroitin Sulfate Glycosaminoglycans are Key Players in Integrin Signaling and Tumor Cell Motility. Clausen TM, Pereira MA, Al Nakouzi N, Oo HZ, Agerbæk MO, Lee S, Orum-Madsen MS, Kristensen AR, El-Naggar A, Grandgenett PM, Grem JL, Hollingsworth MA, Holst PJ, Theander TG, Sorensen PH, Daugaard M, Salanti A. Mol Cancer Res. 2016 Sep 21.
Real-time and label free determination of ligand binding-kinetics to primary cancer tissue specimens; a novel tool for the assessment of biomarker targeting. Clausen TM, Pereira MA, Oo HZ, Resende M, Gustavson T, Mao Y, Sugiura N, Liew J, Fazli L, Theander TG, Daugaard M, Salanti A. Sens Biosensing Res. 2016 Jul;9:23-30.
Molecular dissection of placental malaria protein VAR2CSA interaction with a chemo-enzymatically synthesized chondroitin sulfate library. Sugiura N, Clausen TM, Shioiri T, Gustavsson T, Watanabe H, Salanti A. Glycoconj J. 2016 Jun 10.
Placental Sequestration of Plasmodium falciparum Malaria Parasites Is Mediated by the Interaction Between VAR2CSA and Chondroitin Sulfate A on Syndecan-1. Ayres Pereira M, Mandel Clausen T, Pehrson C, Mao Y, Resende M, Daugaard M, Riis Kristensen A, Spliid C, Mathiesen L, E Knudsen L, Damm P, G Theander T, R Hansson S, A Nielsen M, Salanti A. PLoS Pathog. 2016 Aug 24;12(8):
Burkitt lymphoma express oncofetal Chondroitin Sulfate without being a reservoir for placental malaria sequestration. Mette Ø. Agerbæk, Marina A. Pereira, Thomas M. Clausen, Caroline Pehrson, Htoo Zarni Oo, Charlotte Spliid, Jamie Rich, Vincent Fung, Francis Nkrumah, Janet Neequaye, Robert J. Bigger, Steven J. Reynolds, Giovanna Tosato, Sheeja T. Pullarkat, Leona W. Ayers, Thor G. Theander, Mads Daugaard, Kishor Bhatia, Morten A. Nielsen, Sam M. Mbulaiteye, and Ali Salanti. International Journal of Cancer. 2017 Apr 1;140(7)