Introduction: Platinum-based drug resistance is intricately associated with a disordered tumor metabolic–immune microenvironment (TMIME). This study sought to develop a combined strategy for TMIME reprogramming to enhance cisplatin sensitivity.

Methods: A chemo-gene co-delivery nanoparticle (NP) was engineered using poly(β-amino ester) (PBAE) to encapsulate the cisplatin prodrug (Pt^IV) and CRISPR/Cas9-PKM2 plasmid. The morphology and elemental composition of PPPt^IV NPs were visualized using a transmission electron microscope (TEM) and field-emission TEM. Hydrodynamic size, polydispersity index, and zeta potential were measured using dynamic light scattering. The viabilities and apoptosis effects were investigated in SCC7 and Cal27 cells using CCK-8 and Annexin V/PI double-staining assays. In vivo biodistribution and antitumor efficacy were investigated in SCC7 tumor-bearing C57BL/6 mice.

Results: PPPt^IV NPs exhibited a uniform, near-spherical morphology with a positively charged surface and an average diameter of approximately 150 nm. PPPt^IV NPs possessed good stability and pH-responsive release. Mechanically, PPPt^IV NPs were efficiently internalized through endocytosis and then escaped from lysosomes and released their components. Pt^IV was reduced to cisplatin (Pt^II) via GSH depletion, leading to increased DNA damage and ROS levels to induce apoptosis. CRISPR/Cas9-mediated PKM2 knockdown significantly reduced lactic acid production via inhibiting the Warburg effect while downregulating PD-L1 and HIF-1α levels. These metabolic alterations remodeled the tumor immune microenvironment by promoting dendritic cell maturation, polarizing macrophages to the M1 phenotype, and modulating cytokine release (IFN-γ, TNF-α, IL-12, and IL-10), thereby initiating T cell-mediated antitumor immunity. As a result, PPPt^IV NPs achieved the chemo-immunotherapy goal. Compared to cisplatin alone, PPPt^IV NPs achieved superior antitumor efficacy against both in situ and recurrent tumors with less nephrotoxicity in vivo.

Conclusions: The combined chemo-immunotherapy nanohybrids address the limitations of cisplatin, including resistance and adverse effects, and demonstrate significant potential for clinical application in patients resistant to cisplatin.