Transfer of TCR Genes into Mature T Cells Is Accompanied by the Maintenance of Parental T Cell Avidity

Abstract

The adoptive transfer of tumor-specific T cells expanded in vitro can be of significant therapeutic value in select cancer patients. This strategy is limited though, as it is often difficult, if not impossible, to obtain T cells of clinical value. The transfer of TCR genes to mature T cells to generate tumor-reactive T cells provides a potential mechanism to overcome these limitations. To evaluate the feasibility of such an approach and the quality of the resulting T cells, we generated replication-deficient retroviral vectors using the well-characterized OT-1 TCR genes. After transducing murine T cells, we were able to expand large numbers of Ag-specific T cells that were functionally active against tumor cells expressing the relevant Ag. Furthermore, we found that T cells expressing retrovirally encoded TCR had avidity that was similar to that of the parental clone. This maintenance of avidity was despite variable expression of the retrovirally encoded TCR and the presence of potentially competing endogenous TCRs. These results suggest that the inherent qualities of the TCR, as dictated by the coding sequence, are the most critical parameters in the generation of high-avidity T cells.

Primary Human Lymphocytes Transduced with NY-ESO-1 Antigen-Specific TCR Genes Recognize and Kill Diverse Human Tumor Cell Lines

“…Although many cellular components are potentially responsible for the avid recognition of TAA, the TCR is the main component of this activity (34,35). High avidity of the anti-NY-ESO-1-transduced T cells was demonstrated by their ability to recognize T2 cells pulsed with low amounts of peptide (20 pM; Table III) and the ability to recognize naturally processed peptide found on the surface of diverse HLA-A2-positive tumor cell lines (Figs.…”

Transgenic TCR expression: comparison of single chain with full-length receptor constructs for T-cell function

“…This vector has been reported to be efficient in directing gene expression of both TCR a and b chains on the same vector. [6][7][8] In order to restore the expression of CD3d and z genes, which are required for the surface expression of the TCR-CD3 complex, [13][14][15]28 a vector (SAMEN-CD3dz) for coexpression of both CD3d and z genes was made. After CD3d, z and flTCR genes were cotransduced into BW5147 cells three times; more than 80% of BW5147 cells were detected positive using the H57 mAb (Fig 2b).…”

“…First, incorrect chain pairing between endogenous and transgenic TCR molecules plus possible instability of exogenous TCR a chains might result in suboptimal expression of the desired TCR heterodimers. 6,12 Second, the incorrect a and b chain pairings might alter the TCR antigen recognition specificity leading to autoimmunity. 10 Third, the CD3z chain, which is required for surface expression of the TCR complex, [13][14][15] has been reported to be downregulated in cancer patient T cells, 16 thus limiting the functional efficiency of full-length transgenic TCRs.…”

“…7,8 In the majority of TCR-based studies, full-length TCRs (flTCRs) have been used. [6][7][8][9][10][11] However, the efficiency of flTCR-modified T cells could be compromised by several factors. First, incorrect chain pairing between endogenous and transgenic TCR molecules plus possible instability of exogenous TCR a chains might result in suboptimal expression of the desired TCR heterodimers.…”

“…[1][2][3][4][5][6][7][8] This strategy avoids the limitations of the low frequency of antigen-specific T cells, allowing for facilitated expansion of antigen-specific T cells to therapeutic doses. 7,8 In the majority of TCR-based studies, full-length TCRs (flTCRs) have been used.…”