Background/Objectives: Irinotecan, a camptothecin (CPT) derivative, is commonly used as a first-line therapy for colorectal cancer (CRC), but resistance remains a significant challenge. This study aims to explore the therapeutic potential of FL118, another CPT derivative, with a focus on overcoming resistance to irinotecan. Methods: The effects of FL118 on CRC cells were evaluated, and bioinformatics analysis was performed on RNA-seq data. Transfection was conducted to observe the knockdown effect of survivin, and the in vivo efficacy of FL118 was assessed using a xenograft model. Results: FL118 induces apoptosis, G2/M arrest, and DNA damage. A notable mechanism of action of FL118 is a reduction in survivin levels, which downregulates the expression of RAD51, a key marker of homologous recombination, and attenuates DNA repair processes. Given that SN38 is the active metabolite of irinotecan, FL118 reduces cell viability and RAD51 in SN38-resistant LOVO cells. Conclusions: Our findings provide effective insights into the antitumor activity of FL118 and its potential as a therapeutic agent for overcoming irinotecan resistance in CRC.

Iron regulatory protein (IRP2) plays a key role in regulating iron metabolism and enables cell survival by activating mitochondrial function. Targeting IRP2 to disrupt iron homeostasis is a promising strategy for enhancing the efficacy of cancer treatments. Depletion of IRP2 in breast cancer (BC) cells is associated with sensitivity to radiation therapy (RT), and inhibition of IRP2 prior to RT significantly reduces cell viability compared with radiation treatment alone. This combined therapeutic effects of IRP2 inhibition and radiation treatment were observed in parental and radioresistant cancer cells, significantly enhancing the proportion of cell death. In conclusion, this study proposes that the genetic or pharmacological inhibition of IRP2 in BC cells may serve as a novel therapeutic strategy for increasing radiosensitivity and overcoming resistance by inducing mitochondrial dysfunction.