Anti-TIM3-IFN fusion protein rejuvenates tumor-infiltrating exhausted TIM3+CD8+ T cells through activating intratumoral dendritic cells

While tumor-infiltrating T cells are central to tumor regression, their function is progressively compromised by the exhaustive conditions of the tumor microenvironment. The capacity of intratumoral dendritic cells (DCs) to mitigate this exhaustion state is not fully understood. Here, we investigate a therapeutic strategy that leverages a bispecific DC-T cell engager (BiDT), constructed from anti-TIM3 and IFNa, to simultaneously targeting TIM3 on exhausted TILs and the IFNAR receptor on DCs. Through transcriptional profiling, we elucidate the mechanism by which BiDT operates: it concurrently targets TIM3+ TILs and IFNAR+ DCs, triggering a reprogramming of the local immune repertoire. Mechanistic analysis indicates that BiDT rescues T cells from apoptosis by enhancing Bcl2 expression and restores their effector functions. Crucially, the data uncovers a reciprocal activation loop wherein BiDT-stimulated DCs further potentiate T cell responses via IL-2 and B7/CD28 signaling pathways. We further validated an engineered Pro-BiDT variant designed to limit systemic toxicity. These results underscore the importance of re-establishing functional DC-T cell circuitry as a viable strategy to enhance anti-tumor immunity. Overall design: CD45+ TILs from MC38 tumor (day 19 post-inoculation, control group and BiDT-treated group) were isolated by FACS and anaylzed using single-cell RNA sequencing