Development of a T cell-redirecting bispecific antibody targeting B-cell maturation antigen for the suppression of multiple myeloma cell growth

Abstract Background Multiple myeloma (MM) is the second most common hematological malignancy. It has emerged as one of the next possible hematological diseases amenable to immunotherapy. B-cell maturation antigen (BCMA), a member of the tumor necrosis factor receptor superfamily, is highly expressed in MM cells and is one target with the most potential for developing MM-targeting immunotherapy. Other than the FDA-approved BCMA-targeting CAR T-cell therapy, such as Abecma and CARVYKTI, T cell-engaging multi-specific antibody is another promising therapeutic modality for BCMA-targeting MM treatment. We develop a T-cell redirecting BCMA-targeting bispecific antibody (bsAb) and evaluate its anti-MM activity. Methods We first generated several clones of mouse anti-human BCMA monoclonal antibodies using DNA immunization. One of the anti-BCMA antibodies was then used to design and produce a T cell-redirecting BCMA × CD3 bsAb in CHO cells. Finally, we examined the effect of the bsAb on MM cell growth both in vitro and in vivo. Results The BCMA × CD3 bsAb was designed in a FabscFv format and produced in CHO cells with good yield and purity. Moreover, the bsAb can trigger robust T cell proliferation and activation and induce efficient T cell-mediated MM cell killing in vitro. Using a MM xenograft mouse model, we demonstrate that the bsAb can effectively suppress MM cell growth in vivo. Conclusions Our results suggest that the BCMA × CD3 bsAb in the FabscFv format can efficiently inhibit MM cell growth and have promising potential to be developed into a therapeutic antibody drug for the treatment of MM. Statement of Significance: We have produced a T cell-redirecting BCMA-targeting bsAb that can robustly stimulate T cell proliferation and activation and effectively kill MM cells both in vitro and in vivo. The BCMA bsAb has good potential to be developed into a therapeutic drug for MM treatment.