Therapeutic potential of a tumor-specific, MHC-unrestricted T-cell receptor expressed on effector cells of the innate and the adaptive immune system through bone marrow transduction and immune reconstitution

T-cell receptor (TCR) with unique major histocompatibility complex (MHC)-unrestricted antigen-binding properties was isolated from a human T-cell clone specific for the tumor antigen MUC1. This TCR binds its epitope on the MUC1 protein without the requirement of processing and presentation. A single-chain Vα/Vβ/Cβ (scTCR) was fused to a CD3 zeta (ζ) chain to allow expression on the surface of cells of the innate (granulocytes, macrophages, natural killer [NK] cells) as well as the adaptive (T and B cells) immune system. To test the ability of the cells of the innate immune system to reject a tumor when provided with a tumor antigen-specific TCR, we reconstituted severe combined immunodeficiency (SCID) mice with bone marrow cells transduced with a retroviral vector encoding this receptor and challenged them with a MUC1-positive human tumor. These mice controlled the growth of the tumor significantly better than the control mice. We performed a similar experiment in immunocompetent mice transgenic for human MUC1. Expression of the TCR on large percentages of cells did not result in infiltration or destruction of tissues expressing MUC1. Reconstituted mice controlled the outgrowth of a MUC1-transfected but not the parental control tumor. scTCR expression appears lifelong, suggesting a successful transduction of the self-renewing stem cells.