Tumor-Targeting Properties of Novel Antibodies Specific to the Large Isoform of Tenascin-C

Abstract

Background: The targeted delivery of bioactive molecules with antibodies specific to tumorassociated antigens represents a promising strategy for improving the efficacy of tumor therapy. The large isoform of tenascin-C, an abundant glycoprotein of the tumor extracellular matrix, is strongly overexpressed in adult tissue undergoing tissue remodeling, including wound healing and neoplasia, and has been implicated in a variety of different cancers while being virtually undetectable in most normal adult tissues. Experimental Design: We have used antibody phage technology to generate good-quality human recombinant antibodies (F16 and P12) specific to the alternatively spliced domains A1 and D of the large isoform of tenascin-C. The tumor-targeting properties of F16 and P12 were assessed by biodistribution studies in tumor xenografts using the antibodies in small immunoprotein (SIP) format. Results: SIP(F16) selectively accumulated at the tumor site with 4.5%ID/g at 24 hours in the U87 glioblastoma model but was rapidly cleared from other organs (tumor-to-organ ratios, f10:1). The accumulation of SIP(P12) in the tumor was lower compared with SIP(F16) and persistent levels of radioactivity were observed in the intestine. Conclusions:These data suggest that the F16 antibody, specific to domain A1of tenascin-C, is a promising building block for the development of antibody-based pharmaceuticals in view of its excellent tumor-targeting performance and the strong expression of the antigen in a variety of primary and metastatic tumors.A promising avenue toward the development of more selective anticancer therapies consists in the targeted delivery of bioactive molecules (antibody constant regions, cytokines, drugs, radionuclides, photosensitizers, procoagulant factors, etc.) to the tumor environment by means of ligands specific to good-quality tumor-associated antigens and endowed with suitable pharmacokinetic properties (1 -7).Antigens that are preferentially expressed in the modified tumor extracellular matrix are, in many respects, ideal targets for tumor-targeting applications (2, 8). Extracellular matrix components are often more abundant and more stable than antigens located on the surface of tumor cells. Furthermore, they typically exhibit a low shedding profile and are well accessible to agents (such as antibody derivatives) coming from the bloodstream. In collaboration with the Zardi group (Genova, Italy), our group has extensively shown the tumortargeting potential of antibodies directed against components of the tumor extracellular matrix using, as an example, the L19 human monoclonal antibody (9), specific to the extradomain B of fibronectin (EDB), a marker of angiogenesis (10 -12). The L19 antibody was shown to efficiently target tumor neovasculature and stromal structures in animal models of cancer (13) The EDB domain of fibronectin is a good-quality marker of angiogenesis, which is overexpressed in a variety of solid tumors (renal cell carcinoma, colorectal carcinoma, hepatocellular carcinoma, high-g...

Interfering with pH regulation in tumours as a therapeutic strategy

“…In normal tissues and at pH i values of around 7.0, cells typically produce the 'small' tenascin C splice isoform, which does not include domains A1 to D. When cells are artificially exposed to basic pH values -for example, in cell culture experiments, fetal tissues (which typically have basic pH values of around 7.4-7.5 units) or in aggressive forms of cancer -changes of 0.2-0.3 pH units in the pH i value lead to a complete switch towards the formation of the 'large' tenascin C splice isoform, which includes domains A1 to D 11,12 . Interestingly, tenascin C splice isoforms are commonly found in the tumour stroma and/or around tumour blood vessels [92][93][94][95][96][97][98] and serve as markers of angiogenesis 99 . The regulation of alternative splicing of tenascin C is complicated by the observation that the extra domain C displays a more restricted pattern of expression than the other domains between A1 and D 100,101 .…”

Rationale For Immune-Based Therapies in Merkel Polyomavirus-Positive and -Negative Merkel Cell Carcinomas

“…Tenascin C is expressed on reactive stromal cells in many solid tumor types predominantly around vascular structures [114]. The use of a monoclonal antibody (F16) targeting tenascin C fused to IL-2, enables targeted delivery of IL-2 to reactive tumor vasculature which may help mediate intratumoral immune activation [115].…”

Tenascin-C: Exploitation and collateral damage in cancer management

“…The antibody F16 and its use in cytokine/chemokine combination therapy A fully humanized antibody F16 that specifically recognizes the domain A1 of tenascin-C (generated by alternative splicing) has been developed by the company Philogen. When this antibody, in the small immunoprotein (SIP) format (only comprising the variable regions of the antibody to avoid complications with elimination), was injected into a mouse with a tumor derived from xenografted human glioblastoma cells, it was noted that the antibody accumulated selectively in the tenascin-C rich tumor but not in other parts of the body suggesting a good in vivo specificity 30 encouraging to exploit the possibility whether this antibody detects tenascin-C expression in human cancer tissue. Indeed, the F16-SIP recognized tenascin-C in several human cancer types such as in glioblastoma multiforme 31 (GBM), lymphoma, 32 renal cell carcinoma, 33 lung cancer, 34 head and neck cancer 35 and melanoma 36 which altogether suggested a broad application potential of this antibody.…”