Selection for Anti-transferrin Receptor Bispecific T-cell Engager in Different Molecular Formats

The Transferrin Receptor-Directed CAR for the Therapy of Hematologic Malignancies

As many patients ultimately relapse after chimeric antigen receptor (CAR) T-cell therapy, identification of alternative targets is currently being evaluated. Substantial research efforts are underway to develop new targets. The transferrin receptor (TfR) is prevalently expressed on rapidly proliferating tumor cells and holds the potential to be the alternative target. In order to investigate the efficacy and challenges of TfR-targeting on the CAR-based therapy strategy, we generated a TfR-specific CAR and established the TfR-CAR–modified T cells. To take the advantage of TfR being widely shared by multiple tumors, TfR-CAR T cells were assessed against several TfR⁺ hematological malignant cell lines. Data showed that TfR-CAR T cells were powerfully potent in killing all these types of cells in vitro and in killing T-ALL cells in vivo. These findings suggest that TfR could be a universal target to broaden and improve the therapeutic efficacy of CAR T cells and warrant further efforts to use these cells as an alternative CAR T cell product for the therapy of hematological malignancies.

Overcoming Challenges for CD3-Bispecific Antibody Therapy in Solid Tumors

Immunotherapy of cancer with CD3-bispecific antibodies is an approved therapeutic option for some hematological malignancies and is under clinical investigation for solid cancers. However, the treatment of solid tumors faces more pronounced hurdles, such as increased on-target off-tumor toxicities, sparse T-cell infiltration and impaired T-cell quality due to the presence of an immunosuppressive tumor microenvironment, which affect the safety and limit efficacy of CD3-bispecific antibody therapy. In this review, we provide a brief status update of the CD3-bispecific antibody therapy field and identify intrinsic hurdles in solid cancers. Furthermore, we describe potential combinatorial approaches to overcome these challenges in order to generate selective and more effective responses.