Professor Seoul National University, United States
Introduction:: Immunotherapy has emerged as a promising therapeutic approach for various types of cancer, harnessing the immune system to recognize and eliminate tumor cells. However, systemic administration of immunomodulatory agents often results in severe toxicity and limited efficacy [1]. To overcome these challenges, this study focuses on the localized delivery of cytokine mRNA into the tumor microenvironment (TME) using porous silica nanoparticles (PSNs). PSNs serve as an effective mRNA delivery system by protecting the cargo and promoting cellular uptake [2]. Their physicochemical properties enable localized delivery of the cargo at the site of injection and reduced systemic exposure.
In particular, the study focuses on interleukin-2 (IL-2), an immunostimulatory cytokine known for its anti-tumor effects [3]. To improve IL-2 immunotherapy, we introduce an artificially engineered IL-2 variant (IL-2art) mRNA that minimizes binding to IL-2 receptors responsible for adverse effects [4]. Intratumoral delivery of IL-2art mRNA using PSNs leads to remodeling of the TME, stimulation of immunogenic cancer cell death, and reduction in tumor burden. Additionally, the combination of IL-2art mRNA with an immune checkpoint inhibitor demonstrates enhanced anti-tumor immunity and effective suppression of metastatic tumor growth.
This study highlights the potential of localized cytokine mRNA delivery using PSNs as a promising strategy for localized cancer immunotherapy, addressing the limitations associated with systemic administration.
Materials and Methods:: C57BL/6 and Balb/c mice were obtained from ORIENT BIO and experiments were conducted following institutional guidelines. PSNs were synthesized by modifying a previously published method [5]. Silica nanoparticles were prepared, coated with polyethyleneimine (PEI), and characterized using various techniques. Bioluminescence imaging (BLI) was performed to visualize luciferase activity in mice intratumorally injected with FLuc/PSNs. Tumor models were established by implanting B16F10 or CT26 cells in mice, and tumor growth was monitored. Intratumoral injections of mRNA encoding murine IL-2 and IL-2art were administered every 4 days. Combination treatment included intraperitoneal injections of aPD-1 antibodies. Flow cytometry was used to analyze immune cell populations in tumors, spleens, and lymph nodes. Vascular permeability was assessed by injecting Evans blue dye and measuring its concentration in organs. Acute and subchronic toxicology analyses were conducted by administering high doses of PSNs containing control mRNA and collecting serum samples for analysis.
Results, Conclusions, and Discussions:: The study presents compelling preclinical data supporting the effectiveness of porous silica nanoparticles (PSNs) as a delivery system for mRNA-based immunotherapy. The results demonstrate that PSNs protect mRNA cargo and facilitate its entry into cells. In addition, PSNs enabled highly effective, durable, and localized expression of mRNA within the injection site in mice. This highlights the potential of PSNs for localized mRNA delivery, minimizing off-target effects and providing sustained expression at the site of injection.
Building upon these findings, the study explores the therapeutic potential of delivering mouse IL-2 mRNA using PSNs. The intratumoral delivery of IL-2 mRNA via PSNs not only reduces tumor burden but also mitigates severe systemic toxicity, such as vascular leak syndrome. Furthermore, the study introduces IL-2art mRNA that minimizes binding to IL-2 receptors, resulting in reduced stimulation of immunosuppressive regulatory T cells and enhanced anti-tumor activity.
To further enhance the anti-tumor immune response, the study combines IL-2art mRNA with an immune checkpoint inhibitor. This combination strategy not only reduces tumor burden at the treated tumor but also exhibits systemic effects, effectively suppressing the growth of distant metastatic tumors.
The study also underscores the versatility and potential of PSNs as a drug delivery platform. PSNs offer tunable physicochemical properties and sustained release profiles, making them well-suited for various therapeutic applications. Their rigid and large-sized nanoparticle system enables efficient mRNA delivery while minimizing systemic biodistribution.
In conclusion, this study presents a novel and promising approach for localized delivery of cytokine mRNA using PSNs. The results demonstrate its efficacy in enhancing anti-tumor immunity, reducing tumor burden, and minimizing systemic toxicity. These findings contribute to the development of safer and more effective mRNA-based immunotherapies, showcasing the potential of PSNs as a promising mRNA delivery platform for future applications in cancer treatment.
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References (Optional): : 1. Melero, I., Castanon, E., Alvarez, M., Champiat, S., & Marabelle, A. (2021). Intratumoural administration and tumour tissue targeting of cancer immunotherapies. Nature Reviews Clinical Oncology, 18(9), 558-576. 2. Shin, H., Park, S. J., Yim, Y., Kim, J., Choi, C., Won, C., & Min, D. H. (2018). Recent advances in RNA therapeutics and RNA delivery systems based on nanoparticles. Advanced Therapeutics, 1(7), 1800065. 3. Jiang, T., Zhou, C., & Ren, S. (2016). Role of IL-2 in cancer immunotherapy. Oncoimmunology, 5(6), e1163462. 4. Silva, D. A., Yu, S., Ulge, U. Y., Spangler, J. B., Jude, K. M., Labão-Almeida, C., ... & Baker, D. (2019). De novo design of potent and selective mimics of IL-2 and IL-15. Nature, 565(7738), 186-191. 5. Shin, H., Kang, S., Chae, S. Y., Won, C., & Min, D. H. (2023). Development of a Cancer Nanovaccine to Induce Antigen-specific Immune Responses Based on Large-Sized Porous Silica Nanoparticles. ACS Applied Materials & Interfaces, 15(11), 13860-13868.
