Antibody Based Medicines

Our research goal is to generate original antibody-based medicines for imaging and therapy of cancer.

Professor Kerry Chester

Professor of Molecular Medicine

UCL Cancer Institute

Introduction

Our focus is on design and construction of the molecules and their interaction with cancer targets. The basic antibody fragment we use is a single chain Fv (scFv) [Fig 1] and our primary cancer target is carcinoembryonic antigen (CEA), a glycoprotein expressed in colorectal adenocarcinomas. MFE-23, our most characterised scFv, reacts with CEA and was the first scFv to target cancers in man. Our other targets include breast and prostate cancer and the avß6 integrin which is present on head and neck cancers.

RT Fig1… — **Fig 1:** IgG (150 kD) and scFv (27kD). For scFv, antibody VH and VL chains are genetically tethered with a flexible linker to produce a single polypeptide chain.

We obtain the cancer-reactive scFvs from filamentous phage libraries that contain many millions of diverse antibody specificities and we engineer the scFvs in a format designed or a particular therapy. For example, antibody-directed enzyme-prodrug therapy (ADEPT) of cancer, a treatment that uses a systemically administered anti-tumour antibody-enzyme complex to localize enzyme in tumours. In a second stage, a prodrug is administered and is selectively converted into an active cytotoxic drug by enzyme at the tumour site. [Fig 2].

RT Fig2… — **Fig 2:** ScFv targets enzyme (blue) to antigen on cancer cell (red). Targeted enzyme subsequently catalyzes prodrug into active cytotoxic (green). The toxic drug is thereby restricted to cancerous areas and does not harm healthy organs.

ADEPT has the potential to generate high concentrations of cytotoxic agent selectively within tumours but it is key for success that non-tumour associated enzyme is effectively cleared from blood and other normal tissues before prodrug administration. A recombinant fusion protein, comprising MFE-23 fused to the enzyme carboxypeptidase G2 (CPG2), has been designed and produced by the group to meet this challenge [Sharma et al 2005, Kogelberg et al 2006].

The therapeutic protein is expressed and purified from yeast Pichia pastoris, and the post-translational glycosylation added by this organism is being exploited to control blood clearance via the mannose receptor [Fig 3] and modify bio-distribution. The therapeutic system is effective in pre-clinical tests [Sharma et al., 2006] and is currently in Phase I/II Clinical Trials [Mayer et al., 2006].

Indirect fluorescence confocal microscopy… — **Fig 3:** Indirect fluorescence confocal microscopy of single cell (cytoplasm green, nucleus blue) showing MFECP fusion protein (pink) internalized by human mannose receptor.

The strong translational theme of the group is central to our research thinking. The therapeutics designed by the team can be brought to clinical trial because the group have a dedicated facility which can produce clinical grade microbially-expressed recombinant proteins in compliance with Good Manufacturing Practice (GMP) [Fig 4] [Tolner et al, 2006 a,b;].

Making recombinant therapeutics in GMP facility.… — **Fig 4:** Making recombinant therapeutics in GMP facility.

The Group are also developing new molecular formats for radioimmunotherapy (RIT) and drug delivery and we are exploring a series of scFv fusion proteins with human serum albumin (HSAbodies). These molecules are designed to be multivalent for antigen, have controllable pharmacokinetics and avoid the human immune system. We have shown that HSAbodies have specific tumour uptake and retention [Fig 5] and that there is little kidney accumulation of radio-labelled material during elimination, which is particularly important for RIT.

In vivo localisation of 131I HSAbody… — **Fig 5:** In vivo localisation of 131I HSAbody to viable regions of human tumour xenografts, 24hr post injection. Phosphor image (LHS) and H&E of tumour sections.

We have recently been using scFv molecules to target iron oxide magnetic nanoparticles [Fig 6] which could be used for specific cancer imaging using MRI. A therapeutic application, by creating localized hyperthermia of cancerous tissue upon application of an alternating magnetic field to targeted nanoparticles is also being explored.

Specific localisation of scFv-functionalized magnetic particles… — **Fig 6:** Specific localisation of scFv-functionalized magnetic particles to human cancer cells in vitro.

Cervical cancer discovery offers major new clue to better understand the disease

Microscopic view of human cervix cells. Squamous cell carcinoma (SCC)

Cervical cancer discovery offers major new clue to better understand the disease

Scientists have discovered that cervical cancer can be divided into two distinct molecular subgroups, one far more aggressive than the other, as part of the largest 'omics' study of its kind.

Selected publications

Schumacher FF, Sanchania VA, Tolner B ... Chester KA, Baker JR. Homogeneous antibody fragment conjugation by disulfide bridging introduces 'spinostics'. Sci Rep. 2013;3: 1525.
Goldstein R, Sosabowski J, Vigor K, Chester K, Meyer T. Developments in single photon emission computed tomography and PET-based HER2 molecular imaging for breast cancer. Expert Rev Anticancer Ther. 2013 Mar;13(3): 359-73.
Marquardt J, Begent RH, Chester K, et al. IBC's 23rd Antibody Engineering and 10th Antibody Therapeutics Conferences and the Annual Meeting of The Antibody Society: December 2-6, 2012, San Diego, CA. MAbs. 2012 Nov-Dec;4(6): 648-52.
Chen C, Constantinou A, Chester KA, et al. Glycoengineering approach to half-life extension of recombinant biotherapeutics. Bioconjug Chem. 2012 Aug 15;23(8): 1524-33.
Adair JR, Howard PW, Hartley JA, Williams DG, Chester KA. Antibody-drug conjugates - a perfect synergy. Expert Opin Biol Ther. 2012 Sep;12(9): 1191-206.
Miller J, Doss M, McQuillen R ... Chester K, Robinson MK. Impact of expression system on the function of the C6.5 diabody PET radiotracer. Tumour Biol. 2012 Jun;33(3): 617-27.
Tolner B, Bhavsar G, Foster B, Vigor K, Chester KA (2012). Chapter 37: Production of Recombinant Proteins from Pichia pastoris: Interfacing Fermentation and Immobilized Metal Ion Affinity Chromatography, In: Laboratory Protocols in Fungal Biology; (Eds.) Gupta VK, Tuohy M, et al. Springer Science & Business Media, LLC, 233 Spring Street, New York, NY 10013, USA.
Andrady C, Sharma SK, Chester KA. Antibody-enzyme fusion proteins for cancer therapy. Immunotherapy. 2011 Feb;3(2): 193-211.
Marsh D, Suchak K, Moutasim KA ... Chester KA, et al. Stromal features are predictive of disease mortality in oral cancer patients. J Pathol. 2011 Mar;223(4):470-81.
Vigor KL, Kyrtatos PG, Minogue S ... Chester KA. Nanoparticles functionalized with recombinant single chain Fv antibody fragments (scFv) for the magnetic resonance imaging of cancer cells. Biomaterials. 2010 Feb;31(6): 1307-15.
Meyer T, Gaya AM, Dancey G ... Chester KA, Owen K, et al. A phase I trial of radioimmunotherapy with 131I-A5B7 anti-CEA antibody in combination with combretastatin-A4-phosphate in advanced gastrointestinal carcinomas. Clin Cancer Res. 2009 Jul 1;15(13):4484-92.
Constantinou A, Epenetos AA, Hreczuk-Hirst D, Jain S, Wright M, Chester KA, Deonarain MP. Site-specific polysialylation of an antitumor single-chain Fv fragment. Bioconjug Chem. 2009 May 20;20(5): 924-31.
Yong M, Tolner B, Nagl S, Pedley RB, Chester K, et al. Data standards for minimum information collection for antibody therapy experiments. Protein Eng Des Sel. 2009 Mar;22(3): 221-4.
Kogelberg H, Tolner B, Sharma SK ... Chester KA. Clearance mechanism of a mannosylated antibody-enzyme fusion protein used in experimental cancer therapy. Glycobiology. 2007 Jan;17(1): 36-45.
Mayer A, Francis RJ, Sharma SK ... Chester KA, Begent RH. A phase I study of single administration of antibody-directed enzyme prodrug therapy with the recombinant anti-carcinoembryonic antigen antibody-enzyme fusion protein MFECP1 and a bis-iodo phenol mustard prodrug. Clin Cancer Res. 2006 Nov 1;12(21): 6509-16.

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