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

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, bispecific 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 bispecific CARs can control both wild-type B-cell lymphoma and CD19(-) mutants with equal efficiency in vivo To our knowledge, this is the first bispecific 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. Cancer Immunol Res; 4(6); 498-508. ©2016 AACR

Zah E ，Lin MY ，Silva-Benedict A ，Jensen MC ，Chen YY ... -  《-》

A tandem CD19/CD20 CAR lentiviral vector drives on-target and off-target antigen modulation in leukemia cell lines.

Schneider D ，Xiong Y ，Wu D ，Nӧlle V ，Schmitz S ，Haso W ，Kaiser A ，Dropulic B ，Orentas RJ ... -  《Journal for ImmunoTherapy of Cancer》

CD20-CD19 Bispecific CAR T Cells for the Treatment of B-Cell Malignancies.

Martyniszyn A ，Krahl AC ，André MC ，Hombach AA ，Abken H ... -  《-》

Preserved Activity of CD20-Specific Chimeric Antigen Receptor-Expressing T Cells in the Presence of Rituximab.

CD20 is an attractive immunotherapy target for B-cell non-Hodgkin lymphomas, and adoptive transfer of T cells genetically modified to express a chimeric antigen receptor (CAR) targeting CD20 is a promising strategy. A theoretical limitation is that residual serum rituximab might block CAR binding to CD20 and thereby impede T cell-mediated anti-lymphoma responses. The activity of CD20 CAR-modified T cells in the presence of various concentrations of rituximab was tested in vitro and in vivo CAR-binding sites on CD20(+) tumor cells were blocked by rituximab in a dose-dependent fashion, although at 37°C blockade was incomplete at concentrations up to 200 μg/mL. T cells with CD20 CARs also exhibited modest dose-dependent reductions in cytokine secretion and cytotoxicity, but not proliferation, against lymphoma cell lines. At rituximab concentrations of 100 μg/mL, CAR T cells retained ≥50% of baseline activity against targets with high CD20 expression, but were more strongly inhibited when target cells expressed low CD20. In a murine xenograft model using a rituximab-refractory lymphoma cell line, rituximab did not impair CAR T-cell activity, and tumors were eradicated in >85% of mice. Clinical residual rituximab serum concentrations were measured in 103 lymphoma patients after rituximab therapy, with the median level found to be only 38 μg/mL (interquartile range, 19-72 μg/mL). Thus, despite modest functional impairment in vitro, the in vivo activity of CD20-targeted CAR T cells remains intact at clinically relevant levels of rituximab, making use of these T cells clinically feasible. Cancer Immunol Res; 4(6); 509-19. ©2016 AACR

Rufener GA ，Press OW ，Olsen P ，Lee SY ，Jensen MC ，Gopal AK ，Pender B ，Budde LE ，Rossow JK ，Green DJ ，Maloney DG ，Riddell SR ，Till BG ... -  《-》

Construction of a new anti-CD19 chimeric antigen receptor and the anti-leukemia function study of the transduced T cells.

An N ，Tao Z ，Li S ，Xing H ，Tang K ，Tian Z ，Rao Q ，Wang M ，Wang J ... -  《Oncotarget》