Cytotoxic T lymphocyte-inspired nanotherapeutics chaperoning granzyme B for tumor immune remodeling

T cell-based cancer immunotherapies have transformed oncology; however, their clinical benefit remains limited in immunologically cold tumors, where poor T cell infiltration and impaired effector function weaken endogenous tumor cell killing. Here, we developed GrB@A-nChap, a cytotoxic T lymphocyte (CTL)-inspired nanotherapeutic that chaperones granzyme B (GrB) into the tumor cell cytosol to supplement deficient cytotoxic effector activity in "cold" tumors. Mechanistically, GrB@A-nChap protects GrB under physiological conditions, undergoes partial protonation in the mildly acidic tumor microenvironment to enhance tumor cell uptake, and further responds to lysosomal acidity to promote acidity-dependent lysosomal escape and cytosolic GrB release. Cytosolic GrB then induces mitochondrial dysfunction, caspase-3 activation, and GSDME cleavage, thereby triggering an apoptosis-pyroptosis cascade. This cell death process is accompanied by ICD-associated molecular signals and enhanced dendritic cell maturation. In vivo, GrB@A-nChap treatment was associated with increased intratumoral immune cell infiltration and local immune modulation and enhanced the therapeutic response to αPD-1 treatment. This work establishes a CTLinspired nanotherapeutic that enables cytosolic GrB delivery and provides cell independent GrB-mediated tumor cell killing, offering a potential strategy for complementing existing treatments for cold tumors.