SymphNode Technology: Injectable Microparticles for Immune Modulation and Treatment of Triple-Negative Breast Cancer

Introduction: The aim of this study was to develop and optimize SymphNode platform for the treatment of triple-negative breast cancer (TNBC). Our research focused on designing, fabricating, and testing injectable, biodegradable microporous microparticles with tailored biophysical properties. These microparticles modulate the tumor microenvironment to be more immunogenic, resulting in a tumor-free state in 40% of treated mice with an aggressive TNBC model. Additionally, the treatment prevented tumor recurrence and established robust immunity against TNBC.

Materials and

Methods: In this study, we have designed and fabricating microparticles of varying sizes (20 to 1000 µm), mechanical stiffness (15 to 200 kPa), pore sizes, and antibody conjugation densities. These microparticles enabled the sustained release of therapeutic agents such as TGFβ inhibitors and CpG adjuvant. We tested these microparticles for primary T cell activation and regulatory T cell (Treg) inhibition in vitro, observing high activation rates (over 90%) in primary CD4+ and CD8+ T cells and a substantial reduction in Treg populations using particles with medium to high activation signal intensity. We then evaluated the in vivo efficacy of SymphNode in an aggressive PyMT mouse model of TNBC. This involved assessing tumor growth reduction and the tumor-free state in treated mice. Additionally, we investigated the mechanism of action of SymphNode, focusing on changes in the tumor microenvironment's immune cell populations, such as increases in CD8+ T cells and decreases in Tregs and myeloid-derived suppressor cells (MDSCs). To explore SymphNode's potential to prevent tumor recurrence, we treated mice post-primary tumor removal and monitored tumor recurrence and mass. Lastly, we assessed the long-term efficacy of SymphNode by rechallenging surviving mice with tumor cells to test for durable immunological memory.

Results, Conclusions, and Discussions: Our fabricated microparticles demonstrated controlled release kinetics of therapeutic agents, which is essential for prolonged therapeutic effects. In vitro testing showed high activation rates in primary CD4+ and CD8+ T cells and a substantial reduction in Treg populations. In vivo studies revealed significant tumor growth reduction, with 40% of treated mice becoming tumor-free. This highlights SymphNode's potential as an effective treatment for TNBC. The treatment also resulted in a robust shift towards a more immunogenic tumor microenvironment, evidenced by increased populations of CD8+ T cells and decreased Tregs and MDSCs. Furthermore, treated mice exhibited a significant delay in tumor recurrence and a reduction in tumor mass, indicating the potential of SymphNode as a preventative therapy following surgical tumor removal. The rechallenge experiments demonstrated durable immunological memory, with a high percentage of treated mice remaining tumor-free upon rechallenge. The positive outcomes validate our approach and refine the pathway for potential clinical applications. Our findings underscore the potential of SymphNode as a transformative approach for solid cancer treatment. By demonstrating the ability to modulate the tumor immune environment and effectively reduce tumor burden, we have laid a solid foundation for further development and potential clinical trials. This phase of research supports the eventual submission of an IND application for using SymphNode as a neoadjuvant therapy in human breast cancer, aiming to significantly impact patient health outcomes by providing a novel therapeutic strategy against TNBC.

Acknowledgements (Optional): Research reported in this publication was supported by the National Cancer Institute of the National Institutes of Health under Award Number R44CA281563. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.