In vivo imaging of tumour xenografts with an antibody targeting the potassium channel Kv10.1

Abstract

The Kv10.1 (Eag1) voltage-gated potassium channel represents a promising molecular target for novel cancer therapies or diagnostic purposes. Physiologically, it is only expressed in the brain, but it was found overexpressed in more than 70 % of tumours of diverse origin. Furthermore, as a plasma membrane protein, it is easily accessible to extracellular interventions. In this study we analysed the feasibility of the anti-Kv10.1 monoclonal antibody mAb62 to target tumour cells in vitro and in vivo and to deliver therapeutics to the tumour. Using time-domain near infrared fluorescence (NIRF) imaging in a subcutaneous MDA-MB-435S tumour model in nude mice, we showed that mAb62-Cy5.5 specifically accumulates at the tumour for at least 1 week in vivo with a maximum intensity at 48 h. Blocking experiments with an excess of unlabelled mAb62 and application of the free Cy5.5 fluorophore demonstrate specific binding to the tumour. Ex vivo NIRF imaging of whole tumours as well as NIRF imaging and microscopy of tumour slices confirmed the accumulation of the mAb62-Cy5.5 in tumours but not in brain tissue. Moreover, mAb62 was conjugated to the prodrug-activating enzyme β-D-galactosidase (β-gal; mAb62-β-gal). The β-gal activity of the mAb62-β-gal conjugate was analysed in vitro on Kv10.1-expressing MDA-MB-435S cells in comparison to control AsPC-1 cells. We show that the mAb62-β-gal conjugate possesses high β-gal activity when bound to Kv10.1-expressing MDA-MB-435S cells. Moreover, using the β-gal activatable NIRF probe DDAOG, we detected mAb62-β-gal activity in vivo over the tumour area. In summary, we could show that the anti-Kv10.1 antibody is a promising tool for the development of novel concepts of targeted cancer therapy.

Cyanine Conjugate‐Based Biomedical Imaging Probes

“…[28] More often analogues of endogenous ligands are used for the pursuit of improved pharmacokinetics and safety profile, simplified synthesis, conjugation process, and so forth (Figure 4a). For instance, based on endogenous -(2,9)-oligosialic acid sugar epitope and mannose, -(2,9)-trisialic acid and 2amino-2-deoxymannose were conjugated with cyanine fluorophores for targeted imaging of sia-binding immunoglobulinlike lectins on PC-12 cells (16) and mannose receptors on tumorassociated macrophages (17), respectively. [29] And it is more common in the case of endogeneous peptide ligands, wherein the so-called peptidomimetic strategy is adopted to design warheads that mimic the receptor-ligand interaction.…”

“…Combinatorial chemistry libraries, especially innovative dynamic combinatorial library and DNA-encoded library, commonly involved in target-based drug discovery are also applicable to ligand discovery as their underlying principles are interchangeable. [34] Additionally, biological screening platforms that rely on miscellaneous display systems, either cellular or acellular, to construct genetic mutant libraries www.advancedsciencenews.com www.advhealthmat.de (13)(14)(15) or its biomimetics (16)(17)(18)(19)(20) as targeting warheads. b) 3D image of mouse administered with conjugate 15 using fluorescence imaging tomography (FLIT) mode and confirmation of tumor cells in the primary tumor and four metastatic lymph nodes through H&E staining or cytokeratin immunostaining.…”

Ion channels as therapeutic antibody targets

“…The full-length IgG from which scFv62 was derived has been used for in vivo imaging of tumor xenografts, providing further evidence of the utility of these antibodies in targeted cancer therapy. 199 K v 11.1B K V 11.1 (also known as hERG1) channels are often overexpressed in human cancers, but targeting them risks cardiotoxicity. CD-160,130 is a small molecule compound that blocks K v 11.1 channels with a higher efficacy for the K v 11.1 isoform B, 121 and shows anti-tumor effects without the cardiovascular toxicity induced by K v 11.1 blockade.…”

Monoclonal Antibodies Targeting Ion Channels and Their Therapeutic Potential

“…In such a way, an anti-Kv10.1 mAb (mAb62) was used to target tumor cells in vitro using the human breast MDA-MB-435S cell line and in vivo on tumor models of nude mice (Napp et al, 2016). The authors demonstrated the specific binding and accumulation of the mAb62 in the tumors in vivo for at least 1 week due to the labeling with Cy5.5 fluorophore.…”