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Updated: Aug 1, 2025
Tumor Transplantation for Assessing the Dynamics of Tumor-Infiltrating CD8+ T Cells in Mice
Published on: June 12, 2021
Bispecific T cell-engager targeting oncofetal chondroitin sulfate induces complete tumor regression and protective
Nanna Skeltved1, Mie A Nordmaj1, Nicolai T Berendtsen1
1Centre for Medical Parasitology, Department of Infectious Diseases, University of Copenhagen and, Copenhagen University Hospital, Copenhagen, Denmark.
Background:
The malaria protein VAR2CSA binds oncofetal chondroitin sulfate (ofCS), a unique chondroitin sulfate, expressed on almost all mammalian cancer cells. Previously, we produced a bispecific construct targeting ofCS and human T cells based on VAR2CSA and anti-CD3 (V-aCD3Hu). V-aCD3Hu showed efficacy against xenografted tumors in immunocompromised mice injected with human immune cells at the tumor site. However, the complex effects potentially exerted by the immune system as a result of the treatment cannot occur in mice without an immune system. Here we investigate the efficacy of V-aCD3Mu as a monotherapy and combined with immune checkpoint inhibitors in mice with a fully functional immune system.
Methods:
We produced a bispecific construct consisting of a recombinant version of VAR2CSA coupled to an anti-murine CD3 single-chain variable fragment. Flow cytometry and ELISA were used to check cell binding capabilities and the therapeutic effect was evaluated in vitro in a killing assay. The in vivo efficacy of V-aCD3Mu was then investigated in mice with a functional immune system and established or primary syngeneic tumors in the immunologically "cold" 4T1 mammary carcinoma, B16-F10 malignant melanoma, the pancreatic KPC mouse model, and in the immunologically "hot" CT26 colon carcinoma model.
Results:
V-aCD3Mu had efficacy as a monotherapy, and the combined treatment of V-aCD3Mu and an immune checkpoint inhibitor showed enhanced effects resulting in the complete elimination of solid tumors in the 4T1, B16-F10, and CT26 models. This anti-tumor effect was abscopal and accompanied by a systemic increase in memory and activated cytotoxic and helper T cells. The combined treatment also led to a higher percentage of memory T cells in the tumor without an increase in regulatory T cells. In addition, we observed partial protection against re-challenge in a melanoma model and full protection in a breast cancer model.
Conclusions:
Our findings suggest that V-aCD3Mu combined with an immune checkpoint inhibitor renders immunologically "cold" tumors "hot" and results in tumor elimination. Taken together, these data provide proof of concept for the further clinical development of V-aCD3 as a broad cancer therapy in combination with an immune checkpoint inhibitor.
Insights
The bispecific antibody V-aCD3Mu, targeting cancer cells and T cells, effectively eliminated tumors in mice, especially when combined with immune checkpoint inhibitors. This approach shows promise for broad cancer therapy by activating the immune system against tumors.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- The malaria protein VAR2CSA binds to oncofetal chondroitin sulfate (ofCS), present on most cancer cells.
- A previously developed bispecific construct (V-aCD3Hu) targeted ofCS and human T cells, showing efficacy in immunocompromised mice.
- The current study investigates V-aCD3Mu in immunocompetent mice to assess immune system involvement.
Purpose of the Study:
- To evaluate the efficacy of V-aCD3Mu as a monotherapy and in combination with immune checkpoint inhibitors.
- To assess the anti-tumor effects in a fully functional immune system.
- To provide proof of concept for V-aCD3 as a broad cancer therapy.
Main Methods:
- Production of a bispecific construct (V-aCD3Mu) linking VAR2CSA to an anti-murine CD3 fragment.
- In vitro assessment of cell binding and killing assays.
- In vivo evaluation in syngeneic tumor models (4T1, B16-F10, KPC, CT26) in immunocompetent mice.
Main Results:
- V-aCD3Mu demonstrated efficacy as a monotherapy, with enhanced tumor elimination when combined with immune checkpoint inhibitors.
- Complete tumor elimination was observed in 4T1, B16-F10, and CT26 models.
- Abscopal anti-tumor effects were associated with increased systemic memory and activated cytotoxic/helper T cells, and increased intratumoral memory T cells.
Conclusions:
- V-aCD3Mu combined with immune checkpoint inhibitors can convert "cold" tumors to "hot" tumors, leading to elimination.
- The study provides proof of concept for V-aCD3's potential as a broad cancer therapy.
- Further clinical development of V-aCD3 in combination with immune checkpoint inhibitors is warranted.
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