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Multiple myeloma (MM) is the second most common haematological malignancy. The use of novel drugs and treatment strategies has significantly improved the survival rate of patients with MM. 1 However, MM is still incurable and has frequent relapses. 2 Bispecific antibodies (BsAbs) represent the next generation of immunotherapies and are expected to become an integral part of the MM treatment paradigm. Bcell maturation antigen (BCMA) is widely expressed in MM and normal plasma cells, 3 making it an ideal target for Tcell redirecting therapies. 4 AMG 420, a BCMA/CD3 bispecific T-cell engager (BiTE®) construct, redirects T cells to BCMA-positive tumour cells, resulting in the activation of T-cell mediated lysis of tumour cells. Nevertheless, the short serum half-life of BiTE molecule necessitates administration via continuous intravenous infusion. AMG 420 has been discontinued, and AMG 701, the half-life extended (HLE) BiTE construct has been developed and demonstrated encouraging preliminary responses in patients with relapsed/ refractory MM. 5 Currently, six clinical trials are evaluating BCMA targeting BiTE molecules, and the most recent data in MM have shown promising results with good tolerability. 6 Nevertheless, the universal application of BsAbs is hampered by their complex manufacturing processes and high cost. Compared to treatment with antibodies, plasmid-based gene therapy has clear advantages in terms of production,