Activation of Cell-Intrinsic Signaling in CAR-T Cells via a Chimeric IL7R Domain.

Area of Science:

• Immunology
• Cell Biology
• Biotechnology

Background:

• Chimeric antigen receptor (CAR) T cells offer potent leukemia treatment but often lack long-term persistence.
• Short-lived effector T cells limit sustained antitumor responses, necessitating strategies to enhance CAR T-cell memory.
• Interleukin-7 (IL7) signaling via the IL7 receptor (IL7R) is crucial for memory T cell development, but IL7R expression is downregulated by IL7 exposure.

Purpose of the Study:

• To engineer CAR T cells with sustained IL7Rα signaling for improved persistence and antitumor efficacy.
• To investigate cell-intrinsic cytokine support as a strategy to overcome limitations of exogenous IL7 stimulation.
• To evaluate the functionality and signaling of engineered IL7Rα-based receptors in CAR T cells.

Main Methods:

• Engineered T cells to constitutively secrete IL7 or express an IL7Rα-chimeric cytokine receptor (CCR) targeting acute myeloid leukemia.
• Characterized the phenotype and downstream signaling of engineered T cells upon IL7R activation.
• Coexpressed CAR with the CCR and designed hybrid CAR-CCR constructs, assessing signaling based on membrane proximity.

Main Results:

• Engineered T cells with CCR demonstrated canonical IL7R signaling activation.
• Coexpression of CCR with a cytotoxic CAR maintained the functionality of both receptor systems.
• Hybrid CAR-CCR constructs showed that membrane proximity of intracellular domains is vital for signaling.
• Cell-intrinsic IL7Rα signaling supported CAR T-cell functionality and persistence.

Conclusions:

• Cell-intrinsic provision of IL7Rα-mediated signaling enhances CAR T-cell persistence and antitumor potential.
• Engineering CAR T cells with IL7Rα domains, either independently or within a CAR, offers a viable strategy for sustained anticancer therapy.
• This approach is superior to external IL7 activation for improving T-cell therapy phenotypes.