T Cells Expressing CD19/CD20 Bispecific Chimeric Antigen Receptors Prevent Antigen Escape by Malignant B Cells

Abstract

The adoptive transfer of T cells expressing anti-CD19 chimeric antigen receptors (CARs) has shown remarkable curative potential against advanced B-cell malignancies, but multiple trials have also reported patient relapses due to the emergence of CD19-negative leukemic cells. Here, we report the design and optimization of single-chain, bi-specific CARs that trigger robust cytotoxicity against target cells expressing either CD19 or CD20, two clinically validated targets for B-cell malignancies. We determined the structural parameters required for efficient dual-antigen recognition, and we demonstrate that optimized bi-specific CARs can control both wild-type B-cell lymphoma and CD19− mutants with equal efficiency in vivo. To our knowledge, this is the first bi-specific CAR capable of preventing antigen escape by performing true OR-gate signal computation on a clinically relevant pair of tumor-associated antigens. The CD19-OR-CD20 CAR is fully compatible with existing T-cell manufacturing procedures and implementable by current clinical protocols. These results present an effective solution to the challenge of antigen escape in CD19 CAR T-cell therapy, and they highlight the utility of structure-based rational design in the development of receptors with higher-level complexity.

Axicabtagene ciloleucel, a first-in-class CAR T cell therapy for aggressive NHL

“…Additionally, engineering CAR T cells to express more than one CAR may lessen the ability of tumor cells to downregulate surface proteins targeted by monospecific CAR therapies. The development of bispecific CAR T cells, such as those that recognize both CD19 and CD20, another generally B-cell-specific surface antigen, may increase response rates and improve durability of responses by preventing antigen-loss tumor escape mechanisms [66,67].…”

CAR-T Cells and Allogeneic Hematopoietic Stem Cell Transplantation for Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia

“…Preclinical and early-phase clinical studies have shown that targeting multiple antigens in CAR-T-cell therapy can prevent antigen loss relapses. For example, CAR-T cells targeting CD19/CD20, CD19/CD22, or CD19/CD123, can also improve the extremely limited options and poor outcomes of patients with CD19-negative relapses [58][59][60]. Attention should also be paid to the uncontrolled proliferation of CAR-T-cell therapies.…”

CARs on the Highway: Chimeric Antigen Receptor Modified T Cells for the Adoptive Cell Therapy of Malignant Diseases

“…Such TanCAR induces a T cell response upon engagement of either antigen; both antigens are not needed to be simultaneously present on the same cell to initiate CAR T cell activation. With this respect, CD19-CD20 bispecific CARs were engineered in order to mitigate a B cell leukemia relapse through cells which lost either antigen [49]. In particular, leukemia relapses occurred upon therapy with CD19 CAR T cells, and the relapse is predominantly driven by CD19 − CD20 + leukemic cells which are likely recognized by CD19-and CD20-specific TanCAR T cells.…”