Click Chemistry-Assisted Rejuvenation of Aging T Cells Sensitizes Aged Mice to Tumor Immunotherapy

Enormous resources have been devoted to address the suboptimal response of tumor patients to immunotherapy. However, a crucial yet often overlooked factor in these effects is the strong correlation between the occurrence and development of tumors and the immune dysfunction associated with aging. Our study aims to rejuvenate aging T cells within tumor-draining lymph nodes (TdLNs) by using targeted delivery of rapamycin, a macrolide capable of mitigating aging-related decline in immune function, thereby enhancing the antitumor efficacy of immunotherapy in aged mice. The targeted delivery system relies on a bioorthogonal reaction that harnesses the click chemistry between the azide (N₃) groups artificially introduced onto TdLNs and the dibenzocyclooctyne (DBCO) groups attached to the rapamycin-loaded micelles administered intradermally. Experimental data demonstrate that this approach has effectively restored the functionality of impaired CD8⁺ T cells in aged mice, thereby enhancing the antitumor response to immune checkpoint blockade (ICB) therapy to levels comparable to those in young mice. This study presents a promising strategy to combat the resistance to immunotherapeutic approaches commonly encountered among elderly tumor patients.