This study developed CAR-T cells that recognize the DKK1-A2 complex, demonstrating potent anti-tumor activity against various HLA-A2-positive tumors while exhibiting favorable safety profiles in healthy tissues, indicating broad potential for clinical translation.
Literature Overview
The study titled “T cells engineered against Dickkopf-1-A2 complex can be used to treat HLA-A2+ solid and hematologic cancers,” published in the journal Nature Communications, reviews and summarizes the potential of the Dickkopf-1 (DKK1) and HLA-A2 complex as a novel target for chimeric antigen receptor T-cell (CAR-T) therapy. The research team utilized a T-cell receptor-like monoclonal antibody, C2, to recognize the DKK1-A2 complex presented on the surface of tumor cells, and constructed DKK1-A2 CAR-T cells. They systematically evaluated the anti-tumor activity and safety of these CAR-T cells in multiple hematologic and solid tumor models. Results showed that these CAR-T cells specifically killed tumor cells expressing both HLA-A2 and DKK1, significantly suppressed tumor growth across multiple cancer types, and did not induce significant toxicity in normal tissues. The study further developed a humanized version of the CAR-T cells, which demonstrated improved in vivo persistence and efficacy. This work provides an innovative strategy to extend CAR-T cell therapy to solid tumors and various hematologic malignancies.Background Knowledge
Chimeric antigen receptor T-cell (CAR-T) therapy has achieved remarkable success in treating hematologic malignancies such as B-cell cancers, with CAR-T products targeting antigens like CD19 and BCMA already approved for clinical use. However, CAR-T therapy for solid tumors still faces significant challenges, primarily due to the lack of ideal tumor-specific antigens, immunosuppressive tumor microenvironments, and insufficient T-cell infiltration and persistence. An ideal target should be highly and broadly expressed in tumors but minimally or not at all in normal tissues to avoid off-target toxicity. Dickkopf-1 (DKK1), an antagonist of the Wnt signaling pathway, is highly expressed in various malignancies including multiple myeloma, pancreatic cancer, lung cancer, and triple-negative breast cancer, and its high expression is often associated with poor prognosis. However, as a secreted protein, DKK1 is difficult to target with conventional CAR-T cells that rely on membrane-bound antigens. This study innovatively targets the complex formed by the DKK1 peptide (P20) presented by HLA-A2. This “complex” exists only on the surface of tumor cells and is absent in most normal tissues, thus enabling highly tumor-specific recognition. This strategy combines the advantages of MHC class I restriction and tumor-associated antigens, offering a novel approach to overcome the target selection challenge in CAR-T therapy for solid tumors.
Research Methods and Experiments
The research team first analyzed the expression profile of DKK1 across various hematologic and solid tumors, confirming its high expression in multiple myeloma, pancreatic cancer, non-small cell lung cancer, and triple-negative breast cancer. The specific expression of the DKK1-A2 complex in HLA-A2-positive tumor tissues was validated via immunohistochemistry and flow cytometry, with no detectable expression in normal tissues (except for tonsils). Using the T-cell receptor-like monoclonal antibody C2, which recognizes the DKK1-A2 complex, the team constructed a DKK1-A2 CAR containing scFv, 4-1BB, and CD3ζ domains, and expressed it in T cells. The cytotoxic activity of CAR-T cells against multiple tumor cell lines was evaluated through in vitro cytotoxicity, cytokine release, and proliferation assays. Xenograft models of multiple myeloma, pancreatic cancer, non-small cell lung cancer, and triple-negative breast cancer were established in NSG mice to systematically assess the in vivo anti-tumor efficacy and safety of the CAR-T cells. Additionally, a humanized version of hC2 CAR-T cells was developed, and its functional differences from the murine mC2 CAR-T cells were compared. The therapeutic efficacy was further validated using patient-derived xenograft (PDX) models of pancreatic cancer. T-cell persistence and functionality were evaluated through flow cytometric analysis of memory phenotypes, cytokine release, and re-challenge experiments. Finally, a transgenic mouse model expressing human DKK1 and HLA-A2 was used to assess the potential toxicity of CAR-T cells against normal tissues.Key Conclusions and Perspectives
Research Significance and Prospects
This study successfully developed a novel CAR-T cell therapy that targets the tumor-specific DKK1-A2 complex, overcoming the limitation of conventional CAR-T therapies in solid tumors due to the lack of ideal membrane antigens. By leveraging tumor-associated antigen peptides presented by MHC-I on the tumor cell surface, this strategy achieves highly specific recognition and significantly reduces the risk of off-target toxicity. The potent and safe anti-tumor activity was validated across multiple tumor models, and the success in PDX models provides strong support for clinical translation. The superior performance of humanized CAR-T cells further enhances their clinical prospects.
Future studies should further evaluate the long-term safety of this therapy in larger animal models, particularly its potential impact on tonsillar tissue. Additionally, exploring the applicability of this strategy to other HLA subtypes—such as developing CAR-T cells that recognize DKK1 peptides presented by other HLA alleles—could help expand patient coverage. Furthermore, combining this approach with immune checkpoint inhibitors or strategies targeting the tumor microenvironment may enhance T-cell infiltration and function, improving outcomes in solid tumors. This study offers a highly promising new immunotherapeutic pathway for multiple cancers with high DKK1 expression.
Conclusion
This study proposes and validates an innovative CAR-T cell therapy strategy—targeting the Dickkopf-1 (DKK1) peptide complex presented by HLA-A2 molecules. This complex is specifically and highly expressed in multiple HLA-A2-positive hematologic and solid tumors but absent in the vast majority of normal tissues, providing an ideal tumor-specific target for CAR-T cells. The developed DKK1-A2 CAR-T cells demonstrated robust anti-tumor activity in multiple in vitro and in vivo tumor models, effectively eliminating tumors and significantly prolonging survival. Importantly, the therapy showed no significant toxicity in healthy donor cells or humanized mouse models, confirming its favorable safety profile. Through humanization of the antibody, the persistence and therapeutic efficacy of the CAR-T cells were further enhanced. This work not only offers new therapeutic hope for refractory cancers such as multiple myeloma, pancreatic cancer, lung cancer, and triple-negative breast cancer, but also establishes a universal strategy of using MHC-I-presented tumor antigen complexes as targets for CAR-T therapy, potentially overcoming the bottleneck in solid tumor immunotherapy and offering broad clinical potential.
