An oxygen sensitive self-decision making engineered CAR T-cell

Abstract

A key to the success of chimeric antigen receptor (CAR) T-cell based therapies greatly rely on the capacity to identify and target antigens with expression restrained to tumor cells. Here we present a strategy to generate CAR T-cells that are only effective locally (tumor tissue), potentially also increasing the choice of targetable antigens. By fusing an oxygen sensitive subdomain of HIF1α to a CAR scaffold, we generated CAR T-cells that are responsive to a hypoxic environment, a hallmark of certain tumors. Along with the development of oxygen-sensitive CAR T-cells, this work also provides a basic framework to use a multi-chain CAR as a platform to create the next generation of smarter self-decision making CAR T-cells.

Chimeric antigen receptor (CAR)-transduced natural killer cells in tumor immunotherapy

“…Proteases that are commonly active in the tumor microenvironment can cleave the linker and disengage the masking peptide, thereby enabling CARs to be functional at the local tumor sites. An oxygen-sensitive CAR designed by fusing an oxygen-sensitive subdomain of HIF1α to a CAR scaffold generated CAR-T cells that are responsive to a hypoxic environment, a hallmark of certain tumors, which allows the CAR-T cells to only be effective at local tumor sites [76] . Indeed, in vitro models showed that the CAR surface expression and cytolysis of CAR-T cells were controlled by the oxygen concentration.…”

T-cells “à la CAR-T(e)” – Genetically engineering T-cell response against cancer

“…Additionally, small molecules can be used to induce the transcription of the transgene [297] or the dimerization and assembly of split CAR chains [298]. Induction of CAR function was also exemplified in the case of a HIF-CAR which was design to incorporate HIF1α domain making it sensitive to oxygen and degraded under normoxia conditions [299]. Also, receptor potentiation by proteolysis of a small masking tag degraded in the presence of specific proteases expressed in the tumor microenvironment was elegantly demonstrated for an EGFR-specific CAR [300].…”

Programming CAR-T cells to kill cancer

“…Another feature of the tumour microenvironment that can be explored for context-dependent activation of CARs is the hypoxic milieu generated by inadequate tumour vascularization 95 . This feature has been taken advantage of by the design of a CAR with oxygen-sensitive domains that is degraded in normoxic conditions but remains stabilized in hypoxic conditions 96 . Although the surface expression of this construct was low and the system had a limited dynamic range, it nevertheless demonstrates that the concept of engineering T cells with microenvironmental sensors can enable control over their activity.…”