Multimodal Enhancement of Ferroptosis for Synergistic Cascade Colorectal Cancer Therapy

Emerging research positions ferroptosis as a formidable anti-tumor modality for colorectal cancer (CRC). However, the current pathways to potentiate ferroptosis through a singular or dual approach have fallen short in maximizing treatment efficacy. Herein, a multimodal enhancement strategy of ferroptosis is achieved for synergistic cascade colorectal cancer therapy, via clinical-related drug repurposing and prodrug self-assembly of SN38 and sulfasalazine (SAS). In this process, the SN38 or SAS prodrug is synthesized by conjugating ferrocene via disulfide bonds to SN38 or SAS, then the two prodrugs self-assemble into a hybrid nanomedicine (FSS). FSS exhibited pronounced stability under physiological conditions, while demonstrating rapid disassembly via glutathione-responsive break of disulfide bonds in tumor microenvironments. Then, a multimodal enhancement strategy of cancer ferroptosis is achieved via the SAS-induced regulation of amino acid metabolism, SN38-resulted regulation of glutathione synthesis, accumulation of ferroptosis-related lipid signaling, and ferrocene-directed iron overload in tumors. The potent ferroptosis-based CRC anticancer effects of FSS were systematically explored and confirmed by comprehensive in vitro and in vivo analyses, including cellular experiments, subcutaneous and orthotopic tumor-bearing mouse models, and RNA-sequencing transcriptomic studies. This study lays the groundwork for the clinical translation of multimodal ferroptosis inducers, offering an effective and safe approach to cancer treatment.