Targeted drug delivery to mesothelioma cells using functionally selected internalizing human single-chain antibodies

Abstract

Mesothelioma is a malignancy of the mesothelium and current treatments are generally ineffective. One promising area of anticancer drug development is to explore tumor susceptibility to targeted therapy. To achieve efficient, targeted intracellular delivery of therapeutic agents to mesothelioma cells, we selected a naive human singlechain (scFv) phage antibody display library directly on the surface of live mesothelioma cells to identify internalizing antibodies that target mesothelioma-associated cell surface antigens. We have identified a panel of internalizing scFvs that bind to mesothelioma cell lines derived from both epithelioid (M28) and sarcomatous (VAMT-1) types of this disease. Most importantly, these antibodies stain mesothelioma cells in situ and therefore define a panel of clinically represented tumor antigens. We have further exploited the internalizing function of these scFvs to achieve targeted intracellular drug delivery to mesothelioma cells. We showed that scFv-targeted immunoliposomes were efficiently and specifically taken up by both epithelioid and sarcomatous mesothelioma cells, but not control cells, and immunoliposomes encapsulating the small-molecule drug topotecan caused targeted killing of both types of mesothelioma cells in vitro. [Mol Cancer Ther 2008;7(3):569 -78]

Endocytosis of PEGylated Agents Enhances Cancer Imaging and Anticancer Efficacy

“…Tumor-binding ligands such as peptides (8,9) and antibodies (10,11) may be conjugated to the distal terminus of PEGylated nanoparticles and macromolecules to increase targeting specificity. Thus far, various tumor-associated antigens or receptors have been validated as targets for PEGylated compounds, especially for immunoliposomes (10)(11)(12)(13)(14)(15). These tumor-associated antigens or receptors can be either endocytic or nonendocytic.…”

Robo4 is an effective tumor endothelial marker for antibody-drug conjugates based on the rapid isolation of the anti-Robo4 cell-internalizing antibody

“…This is the main advantage of the present system over the old screening system, which required handling a "polyclonal" pool of mAbs. 6,7 The innovative feature of our method is the use of PSIF as a fusion partner for antibodies in scFv format, thus facilitating the identification of antibody fragments capable of efficient internalization. The scFv fusion is much easier than the chemical conjugation of the antibody to a cytotoxic drug.…”

“…The discovery of potent cellinternalizing mAbs, however, requires labor-intensive screening of a massive number of candidates, and therefore the development of phage display-based methods to identify these candidates is highly desirable. 6,7 In the phage display-based method, a phage antibody library is added to the desired cells and then phages bound to the cell surface are removed. Only internalized phages are rescued from the intracellular compartment.…”

The use of single chain Fv as targeting agents for immunoliposomes: an update on immunoliposomal drugs for cancer treatment

“…Many preclinical studies have confirmed that immunoliposomal drugs targeted by means of scFv are more efficacious than either free drugs or non-targeted liposomal drugs [30,55,70,86,93,94]. In vitro studies by An et al demonstrated that immunoliposomal topotecan targeted by means of an scFv directed against mesothelioma cells were more efficacious than non-targeted liposomal topotecan or the free drug [94].…”

“…In vitro studies by An et al demonstrated that immunoliposomal topotecan targeted by means of an scFv directed against mesothelioma cells were more efficacious than non-targeted liposomal topotecan or the free drug [94]. Recently, Noble et al demonstrated that immunoliposomal vincristine or vinblastine targeted by an anti-HER2 scFv were more efficacious than their respective non-targeted formulations or the free drug, in an animal model of breast cancer [86].…”