Abstract 862: Dynamic hydrogel drug delivery systems for enhancing tertiary lymphoid structure formation and maturation

Introduction: Tertiary lymphoid structures (TLSs), also known as ectopic lymphoid structures, are organized lymphoid-like aggregates that can form within the tumor microenvironment. TLSs exhibit similar structural and functional characteristics to secondary lymphoid organs, such as lymph nodes, and are associated with improved cancer prognosis and enhanced immune responses, including immune checkpoint blockade (ICB) therapies. However, inducing mature TLSs remains a significant challenge. Our study aims to develop a dynamic hydrogel drug delivery system that stimulates the formation and maturation of TLSs. Design: The study involved the synthesis of a hydrogel through supramolecular interactions between 4-(4-chlorophenyl)pyridine-modified hyaluronic acid (HA-CPP) and cucurbit[8]uril (CB[8]). The hydrogel was loaded with the cytokines CXCL13 and LIGHT or with liposomes encapsulating the mRNA coding for these two cytokines, and was injected into cancer-bearing mouse models. We assessed the effect of the hydrogel on TLS formation and maturation through immunofluorescence staining. We also investigated tumor growth and survival rates. Furthermore, we explored the combined effect of the hydrogel and anti-PD1 ICB therapy on tumor suppression and TLS formation. Results and discussion: The study demonstrated that a single injection of the HA-CPP⸦CB[8] hydrogel containing CXCL13 and LIGHT effectively increased TLS density, facilitated TLS maturation, suppressed tumor growth, and extended survival in the intraperitoneal melanoma mouse model. Moreover, the combination of the hydrogel-based drug formulation and anti-PD1 ICB therapy resulted in increased tumor suppression, improved survival rates, and further strengthened TLS formation. Furthermore, although TLS formation in some solid tumor locations like subcutaneous areas was significantly suppressed compared to that in intraperitoneal areas, our mRNA-loaded hydrogel still effectively induced TLS and combated tumors in various subcutaneous tumor models, including melanoma, breast cancer, colon cancer, and pancreatic cancer. This effectiveness is likely due to the adaptability, high translational efficiency, and durable bioactivity of mRNA therapies. Conclusion: The study concludes that the HA-CPP⸦CB[8] hydrogel-based drug formulation acts as an effective synthetic immune niche scaffold for promoting mature TLS formation within tumors. This approach provides a promising strategy for advancing tumor immunotherapy by enhancing the immune response against various cancers and improving the efficacy of ICB therapy. Citation Format: Weilong Tang, Chaiyaporn Kuwentrai, Matthew J. Webber, Zhou Ye, Jiandong Huang. Dynamic hydrogel drug delivery systems for enhancing tertiary lymphoid structure formation and maturation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 862.