Light‐Controllable Binary Switch Activation of CAR T Cells

Abstract

Major challenges to chimeric antigen receptor (CAR) T cell therapies include uncontrolled immune activity, off‐tumor toxicities and tumor heterogeneity. To overcome these challenges, we engineered CARs directed against small molecules. By conjugating the same small molecule to distinct tumor‐targeting antibodies, we show that small molecule specific‐CAR T cells can be redirected to different tumor antigens. Such binary switches allow control over the degree of CAR T cell activity and enables simultaneous targeting of multiple tumor‐associated antigens. We also demonstrate that ultraviolet light‐sensitive caging of small molecules blocks CAR T cell activation. Exposure to ultraviolet light, uncaged small molecules and restored CAR T cell‐mediated killing. Together, our data demonstrate that a light‐sensitive caging system enables an additional level of control over tumor cell killing, which could improve the therapeutic index of CAR T cell therapies.

CAR-T cell therapy for hematological malignancies: Limitations and optimization strategies

“…This spatial-temporal regulation system can achieve attenuated toxicity and has been tested for CD19-CAR-T cells against lymphoma both in vitro and in vivo ( 178 ). Moreover, Kobayashi et al ( 179 ) introduced a light-controlled binary switch system for CAR-T cell activation. They used the aforementioned fluorescein-directed CAR-T cells and an adaptor in which fluorescein is conjugated to small molecules targeting CD38.…”

“…Such adaptors are initially trapped in an ultraviolet (UV)-light-sensitive cage. They are released upon UV exposure to induce CAR-T cell function in vitro ( 179 ).…”

“…The major concern of these light/heat-based systems is that whether light/heat can penetrate into body. It is unlikely for a UV-based system ( 179 ) to reach site of hematological malignancies. By contrary, deep-tissue-penetrable NIR light is able to directly target tumor sites for precise control of CAR-T cells, as demonstrated in murine models of lymphoma ( 178 , 180 ).…”

Clutch Control: Changing the Speed and Direction of CAR-T Cell Therapy

“…To overcome these limitations, we recently described a novel binary-activated CAR-T cell capable of simultaneously targeting multiple tumor antigens in a precise and controllable fashion [20]. By engineering the CAR-T cell to recognize a small molecule and then conjugating the same small molecule to distinct tumor-targeting antibodies, a single small-moleculespecific CAR-T cell can be directed against multiple separate targets to increase the kinetics of tumor-cell lysis.…”

“…While these strategies demonstrate the utility and safety of combinatorial epitope targeting with CAR-T cell therapy, they are limited in that they require separate viral transduction of multiple CAR-T cell constructs or are limited in scope to the initial targets of the infused CAR-T cell population [43,[52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69]. In contrast, our strategy utilizing small-molecule targeted CAR-T cells is adaptable, being capable of simultaneously targeting multiple tumor antigens following the infusion of a single CAR-T cell construct [20].…”