Abstract: Provided herein are chimeric antigen receptors (CAR) that include a spacer sequence that provides for a cell-to-cell distance between a cell expressing the CAR and a target cell. Embodiments are provided in which an extracellular element of CARs include a spacer sequence, wherein, when the CAR is expressed on the surface of a cell, a cell-to-cell distance between the CAR expressing cell and a target expressing cell is between about 17 nm to about 25 nm, inclusive of the endpoints.

Abstract: The present disclosure related to chimeric antigen receptors (CARs) comprising immunoglobulin (Ig) derived spacers, e.g., hinge or loop regions, fragments thereof, or combinations thereof. Ig derived spacer confers improved properties to the CARs, e.g., increased cytokine release with respect the CARs with spacers not derived from hinge regions and fragments thereof, loop regions from constant domains and fragments thereof, and combinations thereof. Also provided are cells expressing CARs comprising Ig derived spacers regions and methods to use the CARs to treat diseases or disorders, e.g., cancer. Some of the disclosed Ig derived spacers are fragments from, e.g., IgA1, IgA2, IgD, IgE, IgG1, IgG2, IgG3, IgG4, or IgM. In some aspects, the disclosed Ig derived spacers are derived from non-human immunoglobulins, e.g., mouse immunoglobulins such IgG2A. Other Ig derived spacer disclosed are modular constructs comprising several concatenated Ig hinges or fragments thereof.