Immunotherapy of B‐cell non‐Hodgkin lymphoma by targeting the chemokine receptor CXCR5 in a preclinical mouse model

Bispecific antibodies are promising agents for immunotherapy. Here, we describe a quadroma‐based trifunctional bispecific antibody binding the chemokine receptor CXCR5 and the T‐cell antigen CD3 that efficiently prevents tumor growth in a mouse B‐cell lymphoma model. CXCR5 regulates the tissue homeostasis of mature B cells and is highly expressed on B‐cell non‐Hodgkin and lymphocyte‐predominant Hodgkin lymphoma, as well as on a subset of CD4+ T cells known as follicular T‐helper cells. In vitro, the bispecific CXCR5::CD3 antibody efficiently recruited effector T cells to CXCR5 expressing B cells and induced a co‐stimulation‐independent activation of CD8+ and CD4+ T cells as demonstrated by the de novo expression of CD25 and CD69, and secretion of the cytokines IFN‐γ, TNF‐α, IL‐6 and IL‐10 by peripheral blood mononuclear cells. Notably, at low antibody concentrations, CXCR5::CD3 displayed a significantly higher cytotoxic activity against autologous B cells than its parental antibodies or rituximab. In vivo imaging revealed that CXCR5::CD3 and its parental CXCR5 antibody efficiently prevent tumor growth in a xenograft model of B‐cell lymphoma in mice and prolong their survival. Taken together, our results identify CXCR5 as a promising target for antibody‐based therapies in the treatment of B‐cell malignancies. What's New? Bispecific antibodies are promising agents for cancer immunotherapy. Here, the authors used the quadroma technology to develop a trifunctional bispecific antibody targeting both the chemokine receptor CXCR5 and the T‐cell antigen CD3. They went on to show that CXCR5::CD3 efficiently depleted CXCR5‐expressing B‐cell non‐Hodgkin lymphoma cells and inhibited the growth of lymphoma xenografts in mice. The findings suggest CXCR5 as a novel target suitable for the immunotherapy of so far incurable B‐cell lymphomas. Since only mature B cells express CXCR5, B‐lineage precursor cells are expected to be preserved during CXCR5::CD3 treatment, in contrast to other biologicals approved for clinical use.