Efficient lysis of CD44v7/8-presenting target cells by genetically engineered cytotoxic T-lymphocytes--a model for immunogene therapy of cervical cancer.

Variant proteins of the CD44 surface glycoprotein family are expressed on many different human tumors and their lymph node metastases. An epitope encoded by sequences of variant exons CD44v7 and v8 and recognized by the monoclonal antibody VFF17 is frequently detected in cervical cancer, whereas the normal cervical epithelium lacks expression of this epitope. We have developed an immunotherapeutic approach for cervical cancer based on the expression of this CD44v7/8 epitope. The single chain antigen-binding fragment of VFF17 was fused to a signal transducing protein (zeta-chain) of the T-cell receptor complex (TCR) and was introduced into a retroviral gene transfer vector. Gene transfer was applied to the murine cytotoxic T-cell line cl96. All recombinant clones expressed the fusion protein on their cell surface. Functionality of the recombinant fusion protein was tested by subjection of several recombinant clones to in vitro cytotoxicity assays. CD44v7/8-expressing target cells were killed efficiently by reprogrammed cl96 in an MHC-independent fashion, whereas CD44v7/ 8-negative cells were not affected. These transfected T cell lines will now be tested in vivo using immune-deficient mice bearing CD44v7/8-expressing tumors.