A spatiotemporally programmed neutrophil-hitchhiking polymeric prodrug potentiates cancer immunotherapy.

Enhancing tumor accumulation after systemic administration while minimizing off-target hepatic deposition remains a major challenge for effective cancer therapy. Herein, we developed a "prime-and-hitch" two-step nanoplatform strategy to address this issue. A PEGylated Ce6 prodrug (CPD) was administered via a single low-dose intratumoral injection, enabling sustained intratumor retention for up to 10 days. Laser irradiation induced a temporally controlled acute inflammatory response, with inflammatory cytokines and neutrophil infiltration peaking at 1 h. In this optimal window, an acidic tumor microenvironment-responsive PEGylated gossypol prodrug functionalized with an anti-Ly6G antibody (αLy6G-pGPD) was intravenously injected to enable binding to circulating neutrophils via Ly6G-specific recognition, thereby achieving neutrophil "hitchhiking"-mediated active tumor targeting. Copper ions (Cu2+) were subsequently coordinated to generate αLy6G-pGPD@Cu, enabling the combined induction of tumor cuproptosis and M1 polarization of tumor-associated macrophages (TAMs). In vivo, the combination of a single low dose CPD administration with repeated laser irradiation and αLy6G-pGPD@Cu treatment markedly suppressed 4T1 tumor growth while increasing the infiltration of cytotoxic T lymphocytes (CTLs) and M1-polarized TAMs within the tumor microenvironment. Collectively, this single low-dose, multiple irradiation-mediated neutrophil hitchhiking strategy provides a robust and versatile platform for extrahepatic targeting delivery and enhanced tumor accumulation of nanotherapeutics.