> Home > Programs > Conferences & Meetings > Previous Symposia > Antibodies 1998 > Zelig Eshhar

Zelig Eshhar, Tova Waks, Cheryl J. Fitzer-Attas, Sara Feigelson, Daniel G. Schindler 
Weizmann Institute of Science
Rehovot, Israel

Redirecting Genetically Engineered Effector Lymphocytes Using Chimeric Receptors with Antibody-Specificity

Tumor-specific CTL are very rare and can be derived and applied for adoptive immunotherapy only in limited number of malignancies. Monoclonal antibodies, on the other hand, can be made quite readily against many tumor associated antigens, nevertheless, their therapeutic application is limited. In order to expand the spectrum of recognition of effector lymphocytes and redirect them to predefined targets, we have endowed T cells with antibody specificity using chimeric receptor genes consisting of antibody variable regions combined with cell activating domains. Several basic designs have been constructed. The first was composed of the two chimeric TCR chains in which the constant regions of the TCR chains were combined with the VH and VL of specific mAb. The second design employed a single-chain Fv of antibody as the recognition unit, linked to the signal transducing g or z sub units of the FcR or CD3 (scFvR). Spacing the scFv from the transmembrane moiety using flexible hinge domains has been found helpful. The scFvR design enables the use of more efficient gene delivery system and allows the use of several lymphocyte receptor sub units, thus extending the potential of the chimeric receptor (T-Body) approach to different cell types. In a third design, we bypassed the TCR complex and connected the extracellular antibody recognition unit through transmembranal (TM) stretch directly to the intracellular Syk tyrosine kinases. Such scFv-Syk chimeric genes were expressed as functional surface receptors in CTL. Upon encountering antigen the chimeric receptors triggered T cell activation. CD8 hinge and TM was found to be the preferential spacer in the chimeric scFv-Syk receptor and could transmit signals leading to phosphorylation, IL-2 release and specific target cell cytolysis. When scFv of anti-human carcinoma antibodies such as the anti-HER2 or anti-folate binding protein mAbs were employed, cytotoxic lymphocytes (either CTL or NK) harboring the chimeric genes could specifically lyse the corresponding human tumor target cells. Finally, when chimeric receptors made by replacing the scFv with the NDF/Heregulin binding domain, the chimeric receptors could target human carcinoma cells overexpressing the Erb family of oncogenic receptors. The optimal parameters for the various chimeric receptor configurations have been determined and the potential application of the “T-Body” approach for gene immunotherapy of cancer will be discussed.