Therapy of human non-small-cell lung carcinoma using antibody targeting of a modified superantigen

Abstract

Summary Superantigens activate T-cells by linking the T-cell receptor to MHC class II on antigen-presenting cells, and novel reactivity can be introduced by fusing the superantigen to a targeting molecule. Thus, an antibody-targeted superantigen, which activates T cells to destroy tumour cells, might be used as cancer therapy. A suitable target is the 5T4 oncofetal antigen, which is expressed on many carcinomas. We constructed a fusion protein from a Fab of a monoclonal antibody recognizing the 5T4 antigen, and an engineered superantigen. The recombinant product 5T4FabV13-SEA D227A bound the 5T4 antigen expressed on the human non-small-cell lung cancer cell line Calu-1 with a K d of 1.2 nM while the substitution of Asp227 to Ala in the superantigen moiety reduced binding activity to MHC class II. 5T4FabV13-SEA D227A tumour reactivity was demonstrated in 7/7 NSCLC samples by immunohistochemistry, while normal tissue reactivity was low to moderate. 5T4FabV13-SEA D227A induced significant T-cell-dependent in vitro killing of sensitive 5T4 bearing Calu-1 cells, with maximum lysis at 10 -10 M, while the capacity to lyse MHC class II expressing cells was approximately 1000 times less effective. Immunotherapy of 5T4FabV13-SEA D227A against human NSCLC was investigated in SCID mice reconstituted with human peripheral blood mononuclear cells. Mice carrying intreperitoneally growing Calu-1 cells showed significant reduction in tumour mass and number after intravenous therapy with 5T4FabV13-SEA D227A . Thus, 5T4FabV13-SEA D227A has highly attractive properties for therapy of human NSCLC.

A phase II study of a 5T4 oncofoetal antigen tumour-targeted superantigen (ABR-214936) therapy in patients with advanced renal cell carcinoma

“…In this, SEA has been engineered for reduced MHC class II binding giving it a much improved safety profile compared to fusions with wild-type SEA (Alpaugh et al, 1998a;Brodin et al, 1998;Forsberg et al, 2001;Cheng et al, 2004). The 5T4 oncofoetal antigen is a transmembrane glycoprotein Stern, 1988, 1990).…”

“…It is expressed by a wide range of cancers (Southall et al, 1990), including gastric, colorectal, ovarian (Dermime et al, 2004), non-small cell lung (NSCLC) (19) and at high levels by 95% of RCC (Forsberg et al, 2001;Griffiths et al, 2005). Despite its widespread expression in malignancy, it shows only limited expression in normal adult tissues (Southall et al,tvjmline 1990;Forsberg et al, 2001), making it an ideal target for antibody-mediated therapy. Renal cell carcinoma is particularly suitable for therapy with ABR-214936 as it is well vascularised and a high proportion (495%) of tumours are positive for 5T4 expression.…”

Combination of Vaccination and Chimeric Receptor Expressing T Cells Provides Improved Active Therapy of Tumors

“…However, in an active therapy model, vaccination with recombinant adenovirus expressing h5T4 before a boost vaccination with a dendritic cell (DC) line expressing h5T4 resulted in a significant improvement in median survival (26 days for control compared with 19 days for the vaccinated animals), while other combinations of vaccines failed to provide an equal degree of antitumor response (26). We are also harnessing the tumor cell surface expression of 5T4 by using Abs to targeted drugs and/or activation of effectors (27,28). Previously, we have shown that human T cells expressing a 5T4-specific CR can specifically lyse 5T4-expressing target cells in vitro (29,30).…”

Cd8 T‐cell recognition of human 5T4 oncofetal antigen

“…Several approaches to developing immunotherapies against this target are under development. Thus, we are harnessing the tumor cell surface expression of 5T4, by using antibodies to targeted drugs and/ or activation of effectors 13,14 or retargeting using chimeric immune receptors of polyclonal T-cell populations. 15,16 Our work in mouse models has shown efficacy of MVA vector-based vaccination for production of tumor-specific immunity.…”