Abstract LB264: Intracavitary gene therapy using miRNA-29b-encoding adeno-associated virus for peritoneal dissemination
Authors: Kaneko Yuki , Ohzawa Hideyuki , Kimura Yuki , Takahashi Rei , Matsumiya Misaki , Tamura Kohei , Futoh Yurie , Miyato Hideyo , Watano Ryota , Mizukami Hiroaki , Sata Naohiro , Kitayama Joji 
Published: April 2024

Abstract
INTRODUCTION: Peritoneal metastasis (PM) is the most critical prognostic factor in gastrointestinal cancers. Notably, the levels of microRNA (miR)-29b in peritoneal fluids have shown significant reduction in patients with PM of gastric cancer. Moreover, supplementation with miR-29b-incorporated exosomes has demonstrated the potential to suppress the formation of PM in a murine model. Nevertheless, given the technical demands associated with this method, we investigated the viability of intracavitary gene therapy as a potentially more advanced and practical approach for clinical implementation.
METHODS: Using the calcium phosphate-based protocol, adeno-associated virus encoding miR-29b (AAV-miR-29b) was constructed, and its effects on mesothelial mesenchymal transition (MMT) were examined using peritoneal mesothelial cells (PMC) derived from human and murine omental tissues. PM was established in C57BL/6 mouse by intraperitoneal (IP) injection of a highly metastatic clone of gastric cancer cell, YTN16P or a pancreatic cancer cell, PAN02. In these syngeneic models, we examined the impact of IP injection of AAV-miR-29b at a single dose of 5 × 1010 vector genome (vg) on PM.
RESULTS: AAV-miR-29b was effectively incorporated into PMCs, resulting in an increased level of miR-29b in extracellular vesicles produced by PMCs. Stimulation of PMCs with TGF-β1 (10ng/ml) decreased the expression of E-cadherin and increased vimentin and fibronectin expression along with enhanced migration activity. Importantly, all the changes were totally abrogated by AAV-miR-29b. Treatment of PMC with TGF-β1 notably increased the attachment of tumor cells, which was also entirely inhibited by AAV-miR-29b. Following IP administration of AAV-miR-29b in vivo, the expression level of miR-29b in peritoneal tissue and intraperitoneal exosomes increased significantly after two weeks. In both murine gastric and pancreatic cancer models, a single IP injection of AAV-miR-29b on day 0 led to a marked reduction in the number of PM nodules in the mesentery (gastric: 38.2 ± 18.7 vs. 8.0 ± 5.2, n=5, P &lt; 0.05; pancreatic: 41.2 ± 7.5 vs. 14.4 ± 16.7, n=7, P &lt; 0.001) and inhibited peritoneal fibrosis associated with PM. AAV-miR-29b elicits the same significant effects when administered on day3. Furthermore, when AAV-miR-29b was administered on day 7 in combination with low-dose Paclitaxel (PTX) (200 µg/mouse), a significant reduction in the number of PM nodules was observed, whereas the effect was not evident with PTX alone (35.8 ± 22.2, n=16 vs. 14.2 ± 16.0, n=12, P &lt; 0.05).
CONCLUSIONS: IP injection of AAV-miR-29b achieved robust transgene expression in PMCs and their exosomes, effectively suppressing MMT and peritoneal fibrosis leading to the inhibition of PM Intraabdominal gene therapy utilizing AAV containing tumor-suppressor miRNA could serve as a promising strategy for both the prevention and treatment of PM.
Citation Format: Yuki Kaneko, Hideyuki Ohzawa, Yuki Kimura, Rei Takahashi, Misaki Matsumiya, Kohei Tamura, Yurie Futoh, Hideyo Miyato, Ryota Watano, Hiroaki Mizukami, Naohiro Sata, Joji Kitayama. Intracavitary gene therapy using miRNA-29b-encoding adeno-associated virus for peritoneal dissemination [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB264.