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TCR-like human antibodies expressed on human CTLs mediate antibody affinity-dependent cytolytic activity
Patrick Chames1, Ralph A Willemsen, Gertrudis Rojas
1Department of Pathology, Maastricht University, Maastricht, The Netherlands.
Abstract:
The permanent genetic programming via gene transfer of autologous T cells with cell surface receptors directed toward tumor-related Ags holds great promise for the development of more-specific tumor therapies. In this study we have explored the use of Abs directed to MHC-peptide complexes (or TCR-like Abs) to engraft CTLs with exquisite specificity for cancer cells. First, we affinity matured in vitro a previously selected TCR-like Ab, Fab-G8, which is highly specific for the peptide melanoma-associated Ag-A1 presented by the HLA-A1 molecule. A combination of L chain shuffling, H chain-targeted mutagenesis, and in vitro selection of phage display libraries yielded a Fab-G8 Ab derivative, Fab-Hyb3, with an 18-fold improved affinity yet identical peptide fine specificity. Fab-G8 and Fab-Hyb3 were expressed on primary human T lymphocytes as cell surface-anchored Fab, demonstrating that T cells expressing the high-affinity Fab-Hyb3 molecule eradicate tumor cells much more effectively. Furthermore, the gain in ligand-binding affinity resulted in a 2-log improvement in the detection of peptide/MHC complexes on melanoma-associated Ag-A1 peptide-loaded cells. In summary, an affinity-matured Ab specifically recognizing a cancer-related peptide/MHC complex was generated and used to improve the tumor cell killing capacity of human T cells. This strategy, based on engraftment of T cells with in vitro engineered Abs, is an attractive alternative to the laborious, and in many cases unsuccessful, generation of highly potent tumor-specific T lymphocytes.
Insights
Researchers engineered T cells with enhanced antibody receptors to target cancer cells more effectively. This improved cancer therapy by increasing the specificity and killing capacity of T cells against tumors.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- T-cell-based cancer therapies offer specificity but often face challenges in generating potent, tumor-specific T lymphocytes.
- Engineering T cells with chimeric antigen receptors or T-cell receptors (TCRs) is a promising approach for cancer treatment.
Purpose of the Study:
- To develop and evaluate engineered T cells with enhanced specificity for cancer cells using affinity-matured antibody fragments targeting MHC-peptide complexes.
- To improve the tumor cell-killing capacity of T lymphocytes through genetic programming with novel antibody receptors.
Main Methods:
- Affinity maturation of a TCR-like antibody (Fab-G8) targeting a melanoma-associated antigen presented by HLA-A1, resulting in Fab-Hyb3 with 18-fold higher affinity.
- Expression of engineered antibody fragments (Fab-G8 and Fab-Hyb3) on primary human T lymphocytes as cell surface-anchored Fab.
- Assessment of tumor cell eradication efficacy and detection of peptide/MHC complexes by engineered T cells.
Main Results:
- The high-affinity Fab-Hyb3 molecule significantly enhanced the tumor cell-killing capacity of engineered T cells compared to the original Fab-G8.
- A 2-log improvement in the detection of target peptide/MHC complexes was observed with the high-affinity antibody.
- Engineered T cells demonstrated improved specificity and efficacy in targeting cancer cells.
Conclusions:
- Affinity-matured antibodies recognizing cancer-specific peptide/MHC complexes can be effectively used to engineer T cells for enhanced tumor therapy.
- This strategy provides a viable alternative to traditional methods for generating potent tumor-specific T lymphocytes.
- The engineered T-cell approach holds significant promise for developing more specific and effective cancer treatments.