Bispecific T cell-engager targeting oncofetal chondroitin sulfate induces complete tumor regression and protective immune memory in mice

Nanna Skeltved, Mie A. A. Nordmaj, Nicolai T. Berendtsen, Robert Dagil, Emilie M. R. Stormer, Nader Al-Nakouzi, Ke Jiang, Alexandra Aicher, Christopher Heeschen, Tobias Gustavsson, Swati Choudhary, Ismail Gogenur, Jan P. P. Christensen, Thor G. G. Theander, Mads Daugaard, Ali Salanti, Morten A. A. Nielsen

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Abstract

BackgroundThe 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-aCD3(Hu)). V-aCD3(Hu) 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-aCD3(Mu) as a monotherapy and combined with immune checkpoint inhibitors in mice with a fully functional immune system.MethodsWe 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-aCD3(Mu) 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.ResultsV-aCD3(Mu) had efficacy as a monotherapy, and the combined treatment of V-aCD3(Mu) 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.ConclusionsOur findings suggest that V-aCD3(Mu) 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.

OriginalsprogEngelsk
Artikelnummer106
TidsskriftJournal of Experimental & Clinical Cancer Research
Vol/bind42
Antal sider16
ISSN1756-9966
DOI
StatusUdgivet - 2023

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