Multifunctional Peptides to Improve Nucleic Acid Delivery for Ovarian Cancer Treatment

RNA interference (RNAi) therapies, such as small interfering RNA (siRNA), offer a high-precision approach to reducing the expression of disease-promoting genes with minimal off-target effects. For aggressive diseases like ovarian cancer, RNAi therapy can serve as a robust treatment modality if delivered successfully. Over 70% of ovarian cancer patients are diagnosed in stages three and four, where the disease becomes more difficult to treat. High relapse rates and drug resistance in these stages demonstrate the need for novel strategies to sensitize tumors to chemotherapy, making siRNA a promising avenue for targeting resistance-associated oncogenes. However, the delivery of siRNA remains a significant challenge. As of 2024, the FDA has only approved six siRNA therapies, none of which are for cancer treatment, and all are limited to targeting the liver. Expanding siRNA delivery beyond the hepatic niche is critical for advancing the treatment of ovarian cancer and other diseases. One promising strategy to overcome the barriers of siRNA delivery is by using peptide-based nanoparticle delivery systems. There are several classes of peptides that can be rationally designed and tailored for a wide range of functionalities as nucleic acid carriers. Our lab has previously designed a novel fusogenic peptide sequence capable of delivering siRNA to ovarian tumors in vivo. Despite its success in delivering siRNA intratumorally, regional delivery via intraperitoneal (IP) injections was modest. Therefore, this work developed and characterized multifunctional tandem peptides, consisting of targeting and fusogenic peptide sequences combined with flexible and cleavable linkers, and assessed their potential for regional and systemic delivery of siRNA to ovarian tumor tissue. We first demonstrated that these peptide sequences effectively bind, protect, and deliver siRNA to ovarian cancer cells in vitro, resulting in significant silencing of an oncogene associated with cell invasion and migration. We then selected the most promising tandem peptide and assessed its delivery efficiency to IP ovarian tumors, comparing regional IP and systemic intravenous (IV) administration. Our results showed that the tandem peptide enhanced siRNA delivery to IP tumors compared to the fusogenic peptide when administered intraperitoneally. Finally, we examined the silencing of chemoresistance-associated genes in a 3D tumor spheroid model to resensitize in vitro microtumors to chemotherapy. Our results showed a reduction in tumor spheroid viability in concurrent and sequential combination delivery studies. Altogether, this work demonstrates the utility of a targeted tandem peptide for enhancing delivery and therapeutic efficacy of siRNAs. Harnessing the unique properties of these engineered peptides may provide new targeted RNAi therapies not only for ovarian cancer but also for other diseases where RNAi therapy holds therapeutic promise.