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Women's Health

Women's Health - Poster Session C & D

Z34 - Intraperitoneal administration of enzyme-cleavable multifunctional peptides for siRNA delivery to ovarian tumors

Friday, October 10, 2025
10:00 AM - 11:00 AM PDT
Location: Exhibit Hall F, G & H

Introduction: : Ovarian cancer remains the most lethal gynecological malignancy, accounting for the loss of hundreds of thousands of women’s lives worldwide each year. The efficacy of standard- of- care treatment regimens is limited by late-stage diagnosis as well as inherent and acquired resistance. Gene therapy utilizing RNA-interference (RNAi) offers a strategy to enhance treatment efficacy by inhibiting cancer-promoting genes using RNA molecules, such as small interfering RNA (siRNA). Effective siRNA delivery requires a targeted delivery to overcome multiple biological barriers, including nuclease-mediated degradation, inadequate cellular internalization, and rapid organ clearance. To address these barriers, we previously developed a stimuli-responsive fusogenic peptide, DIV3W, and combined it with a luteinizing hormone-releasing hormone receptor (LHRHR) targeting peptide to create the GF-LD tandem peptide, which is joined with an enzyme-cleavable linker. Previous in vitro studies have demonstrated that our peptides are stable, cytocompatible, and capable of self-assembling with siRNA to prevent degradation. Here, we utilize intraperitoneal (IP) administration to assess the stability and bioaccumulation of siRNA delivered via DIV3W and GF-LD in a murine model of advanced-stage ovarian cancer.

Materials and

Methods: : We employed an in vivo mouse model to examine the therapeutic potential of the GF-LD targeting peptide for IP delivery of RNAi therapy into ovarian tumor tissue. Female athymic nude mice were injected with fluorescently labeled ES-2 ovarian cancer cells in the lower right abdominal quadrant to model IP metastasis in advanced-stage ovarian cancer. After tumors were established, mice were treated with DIV3W or GF-LD peptides complexed with fluorescently labeled Cy5.5 siRNA via IP injection. The biodistribution of siRNA was tracked using an in vivo imaging system (IVIS) over a 48-hour period following injection. At 48 hours post-injection, mice were euthanized in accordance with Clemson IACUC and GSRC protocols, and organs were harvested for ex vivo imaging. Ex vivo fluorescence of tissue was quantified using Aura Imaging Software ROI analysis.

Results, Conclusions, and Discussions:: Systemic biodistribution was monitored for 48 hours post-IP administration of siRNA either without a carrier (free siRNA), or with our DIV3W or GF-LD peptides. At one hour, all treatment groups emitted strong fluorescent signal from the IP cavity. The fluorescent signal showed no significant decline for the DIV3W and GF-LD treatment groups versus the free siRNA group until 12 hours post-injection. Beyond the 12-hour mark, a decrease in fluorescence was observed indicating tumor internalization or metabolic breakdown of the siRNA (Figure 1A). At 48 hours, the DIV3W and GF-LD treatment groups exhibited residual fluorescent signal, while none remained in the free siRNA group. Quantitative ROI analysis of whole-body IVIS imaging revealed that the DIV3W and GF-LD treatment groups exhibited higher photon emission over time versus the free siRNA group (Figure 1B). This indicates that our peptide nanocarriers enhance the stability of siRNA within the IP cavity, potentially improving the therapeutic benefit. Following 48 hours of whole-body imaging, tumors were excised to assess siRNA localization across specific organs. Ex vivo imaging detected increased fluorescence intensity in the tumor tissue of the DIV3W and GF-LD treatment groups when compared to the free siRNA group (Figure 1C). Quantitative ROI analysis confirmed this visual representation with a significant increase in photon emission in DIV3W- and GF-LD-treated tumor tissue compared to the free siRNA treatment group. The GF-LD treatment group exhibited a 44% increase in siRNA tumor accumulation versus the DIV3W treatment group, and a 143% increase in siRNA tumor accumulation compared to treatment with free siRNA (Figure 1D). This can likely be attributed to the addition of the LHRHR targeting region in the GF-LD peptide, which is not present in the DIV3W peptide. Off-target tissue accumulation was present in all three treatment groups, though no statistically significant increase in accumulation was observed in the DIV3W and GF-LD treatment groups compared to the free siRNA control. These results indicate that the GF-LD peptide-based nanocarrier can be delivered to the IP cavity and promote siRNA retention and localization within tumor tissue. This technology has the potential to enhance gene-targeted therapies and improve outcomes in ovarian cancer.

Acknowledgements and/or References (Optional): : This research was funded in-part by Materials Assembly and Design Excellence in South Carolina (MADE in SC) under National Science Foundation (NSF) Award #OIA-1655740 (AAB) and the NSF CAREER Award #2046694 (AAB). Data presented in this publication were partially collected using SC BioCRAFT facilities supported by the National Institute of General Medical Sciences (NIGMS) of the National Institutes of Health (NIH) under award number P30 GM131959 (AAB). Any opinions, findings, conclusions, or recommendations expressed are those of the author(s) and do not necessarily reflect the views of the NSF and NIH. Support was also provided by Clemson’s Call Me Doctor Fellowship (KLA), the Clemson University Honors College (RX), and the Clemson Creative Inquiry program (RX and CJ).