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Published on: September 25, 2018
Identification of novel KRASG12D neoantigen specific TCRs and a strategy to eliminate off-target recognition
Xiaojian Han1,2, Xiaxia Han1,2, Yanan Hao1,2
1Department of Immunology, School of Basic Medical Sciences, Chongqing Medical University, Chongqing, 400010, China.
Background:
T cell receptor (TCR)-engineered T cells targeting neoantigens originated from mutations in KRAS gene have demonstrated promising outcomes in clinical trials against solid tumors. However, the challenge lies in developing tumor-specific TCRs that avoid cross-reactivity with self-antigens to minimize the possibility of severe clinical toxicities. Current research efforts have been put towards strategies to eliminate TCR off-target recognition.
Methods:
Naive T cell repertoire was used for screening KRASG12D-reactive TCRs. Specific TCRs were subsequently identified and their functionality was assessed using TCR Jurkat cells and TCR T cells. Peptide specificity was evaluated using the X-scan assay. To enhance TCR specificity for KRASG12D and reduce their reactivity to self-peptide SMC1A29-38, mammalian TCR display libraries were employed for the design of modification in the complementarity-determining region (CDR).
Results:
HLA-A*11:01-restricted TCRs targeting the KRASG12D epitope were isolated, and TCR1 was characterized with superior functional avidity and specificity. Alongside a robust recognition of endogenous KRASG12D epitope, this TCR displayed cross-reactivity with the SMC1A29-38 epitope. With an approach utilizing structural-guided mutations in the CDR-1A region of TCR1, we obtained an engineered TCR variant (TCR1a7). Functional characterization of TCR1a7 showed that this TCR not only exhibited enhanced specificity towards KRASG12D, but also demonstrated successful elimination of the off-target recognition of SMC1A29-38.
Conclusions:
TCRs targeting the KRASG12D peptide could be isolated from naive T cell repertoires. Integrating the TCR-peptide-HLA complex structure with a mammalian TCR library system could serve as a functional strategy to reduce potential TCR cross-reactivity with self-antigens, such as SMC1A29-38. Our findings evidenced an operable method to enhance TCR peptide specificity, while maintaining advanced functional avidity and potent anti-tumor activity.
Insights
Engineered T cell receptors (TCRs) targeting KRAS mutations show promise for cancer therapy. Researchers enhanced TCR specificity to KRAS neoantigens while eliminating self-antigen reactivity, improving safety for solid tumor treatments.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- T cell receptor (TCR)-engineered T cells targeting KRAS mutations show promise in solid tumor treatment.
- A key challenge is developing tumor-specific TCRs to avoid self-antigen cross-reactivity and severe toxicities.
- Strategies to eliminate TCR off-target recognition are crucial for improving safety and efficacy.
Purpose of the Study:
- To isolate and characterize KRAS-specific TCRs from naive T cell repertoires.
- To engineer TCRs with enhanced specificity for KRAS neoantigens and reduced reactivity to self-peptides.
- To evaluate the efficacy of engineered TCRs in preclinical models.
Main Methods:
- Screening of naive T cell repertoire for KRASG12D-reactive TCRs.
- Functional assessment using TCR Jurkat and T cells, and peptide specificity evaluation via X-scan assay.
- Employing mammalian TCR display libraries and structural-guided mutations in complementarity-determining regions (CDRs) to enhance specificity.
Main Results:
- Isolation of HLA-A*11:01-restricted TCRs targeting KRASG12D, with TCR1 showing high avidity and specificity.
- TCR1 exhibited cross-reactivity with the self-peptide SMC1A29-38.
- An engineered variant, TCR1a7, demonstrated enhanced KRASG12D specificity and eliminated SMC1A29-38 cross-reactivity.
Conclusions:
- KRASG12D-targeting TCRs can be isolated from naive T cell repertoires.
- Integrating TCR-peptide-HLA structure with TCR library systems effectively reduces self-antigen cross-reactivity.
- The developed method enhances TCR peptide specificity, maintains functional avidity, and supports potent anti-tumor activity.
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