Engineering a Second Interchain Disulfide Bond in the αβ T-Cell Receptor Constant Domain: A Powerful Strategy to Enhance Stability, Pairing Fidelity, and Therapeutic Efficacy in TCR-T Cell Therapy.

Adoptive TCR-T cell therapy holds great promise for personalised cancer treatment, yet it is limited by poor surface expression, chain mispairing, and suboptimal stability of introduced TCRs. One effective structure-guided approach is to introduce a second interchain disulfide bond between the α and β constant domains. This review summarises the structural and mechanistic basis of this strategy, its impact on TCR folding, CD3 assembly, mechanotransduction, and anti-tumour function, as well as current engineering approaches, persistent challenges, and future perspectives. Preclinical studies demonstrate improved heterodimer stability, reduced mispairing, higher surface expression, and enhanced signalling, positioning the second disulfide bond as a valuable complementary tool in next-generation TCR engineering.