Conditional control of universal CAR T cells by cleavable OFF-switch adaptors

Abstract

As living drugs, engineered T cell therapies are revolutionizing disease treatment with their unique functional capabilities. However, they suffer from limitations of potentially unpredictable behavior, toxicities, and non-traditional pharmacokinetics. Engineering conditional control mechanisms responsive to tractable stimuli such as small molecules or light is thus highly desirable. We and others previously developed universal chimeric antigen receptors (CARs) that interact with co-administered antibody adaptors to direct target cell killing and T cell activation. Universal CARs are of high therapeutic interest due to their ability to simultaneously target multiple antigens on the same disease or different diseases by combining with adaptors to different antigens. Here, we further enhance the programmability and potential safety of universal CAR T cells by engineering OFF-switch adaptors that can conditionally control CAR activity, including T cell activation, target cell lysis, and transgene expression, in response to a small molecule or light stimulus. Moreover, in adaptor combination assays, OFF-switch adaptors were capable of orthogonal conditional targeting of multiple antigens simultaneously following Boolean logic. OFF-switch adaptors represent a robust new approach for precision targeting of universal CAR T cells with potential for enhanced safety.

Electrophilic proximity-inducing synthetic adapters enhance universal T cell function by covalently enforcing immune receptor signaling

“… 12 , 13 By creating a library of molecular adapters, a T cell engineered with a single universal SAR can be directed against multiple tumor targets and tailored to the antigenic repertoire of the tumor, thereby reducing the need for multiple engineering runs to produce T cells with distinct antigen specificity. Pre-clinical studies have confirmed the utility of this strategy in the treatment of hematologic and solid tumor models using a variety of donor moieties 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 and the approach is currently being tested in clinical trials.…”

“…Numerous molecular adapter approaches have been evaluated for templating ternary complexes that bridge universal CARs with tumor antigens. 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 Bifunctional small molecule adapters are attractive tools for directing universal CARs due to their ease of production, high tumor penetrance, and low immunogenicity. We reasoned that covalent attachment of the small molecule adapter to a universal receptor could enhance functionality of the receptor.…”