Impact of Topical Deferoxamine Used as a Radioprotective Agent on the Efficacy of Radiation Therapy in a Murine Model of Human Breast Cancer

PURPOSE: This study investigates the impact of Deferoxamine Intradermal Delivery Patch (DIDP, Tautona-Group), applied topically as a skin radioprotectant, on the efficacy of radiation therapy. While the radioprotective properties of DIDP on the skin have been well-established in previous in vivo studies, its potential protective effects on cancer cells subjected to radiotherapy remain largely unexplored. Therefore, this research aims to elucidate whether the application of DIDP on the skin overlying tumor interferes with the induction of apoptosis in cancer cells following radiation therapy. Our research provides valuable insights into the interplay between DIDP as a radioprotective agent and the therapeutic effectiveness of radiation therapy in cancer treatment. METHOD: The study was performed on a murine model of human breast cancer developed by injecting 1x10^6 MCF7-Luc2 cancer cells (ATCC) into the mammary gland of 8-week-old female immunodeficient NSG mice. Once tumors reached an intensity of ~1x108 photons/s, mice were assigned to one of two cohorts: control and DFO-treated. DIDP were applied daily for 30 days until study endpoint. Radiation therapy (5 x 2 Gy dose daily; total 10 Gy) was administrated on the last 5 days of DIDP treatment using the RS-2000 irradiator (RadSource). The non-irradiated control mice were used to establish a baseline. Pre- and post-radiation in vivo tumor size was assessed using luciferin injection and LAGO bioluminescence imaging system. The day following radiation therapy, skin and tumor samples were preserved in 10% formalin and embedded in paraffin for downstream analyses. TUNEL staining (Abcam) and ImageJ software were utilized to detect and quantify the number of apoptotic cells. Statistical analysis was performed using ANOVA and GraphPad Prism software, with p < 0.05 considered significant. RESULTS: The quantitative analysis of TUNEL staining revealed a significant increase in the number of apoptotic cells in both the control group (FC=3.81, p<0.0001) and the DFO-treated group (FC=3.95, p<0.0001) following radiation therapy, indicating that irradiation was effective in both cohorts. Importantly, no significant differences were observed in the number of apoptotic cells when comparing irradiated control to irradiated DFO-treated mice (FC=0.8, p=0.131), suggesting that DIDP does not interfere with the efficacy of radiation therapy. Additionally, bioluminescence assays demonstrated no significant differences in tumor size after radiation therapy between the control and DFO-treated groups (FC=0.8, p=0.486). These findings further confirm that DIDP does not influence negatively the therapeutic effects of radiotherapy in breast cancer cells. CONCLUSION: This study highlights the importance of evaluating the in vivo effects of radioprotective agents on cancer treatment outcomes to ensure their oncological safety. Specifically, we address the gap in understanding the interaction between DIDP and radiation therapy. The presented findings indicate that topical DFO treatment poses minimal risk of interfering with radiation therapy, as shown by no significant difference in tumor growth and tumor cell apoptosis following radiation therapy. DIDP does not compromise the efficacy of radiation therapy, most likely due to its inability to penetrate deeper tissues. In conclusion, our study suggests that DIDP may be safely used as a radioprotective treatment in oncological settings.