CD4+ T Cell Activating Hydrogels for Cancer Immunotherapy

Project Summary Adoptive cell therapy (ACT) treatment, in which cancer patients are re-infused with expanded autologous tumor-specific CD8+ T cells, has demonstrated some success in treating solid cancers like melanoma. However, the approach's overall complexity, cost, and insufficient clinical efficacy have limited its widespread application. To overcome these barriers, recent research has shifted towards innovative technologies, such as artificial antigen presenting cells (aAPCs), which offer a more adaptable and cost- effective solution for enhancing T cell responses for use in ACT. The goal of our proposed project is to advance this field by developing a cutting-edge aAPC platform, termed the artificial lymph node (aLN), that is specifically designed for the in vivo generation of CD4+ T cells. This system will consist of two distinct technologies: (1) MHC II-based aLNs to study and promote the generation of CD4+ cytotoxic T cells and (2) combined MHC I and II aLNs for the expansion of helper CD4+ T cells to improve CD8+ T cell function. The platform is made from a particulated hyaluronic hydrogel, that is conjugated with the three signals required for optimal T cell activation and expansion. We will investigate the effects of biomaterial properties and signal incorporation on in vitro T cell activation, as well as gain insight into in vivo antigen-specific T cell activation in a tumor-burdened host. We will develop advanced aLN microparticles (MPs) for in vivo injection to improve T cell activation for cancer immunotherapy. We will first explore biomolecular cues, focusing on the effects of antigen-specific stimulation with class II peptide-MHC molecules and examining how physical properties like ligand density and stiffness affect CD4+ T cell activation, proliferation, and cytotoxic function. We will also evaluate the effects of different signal 2 and signal 3 on CD4+ T cell phenotype and function, and refine aLN MP properties for effective human CD4+ T cell expansion using PADRE. Next, we will create aLN platforms that stimulate both CD4+ and CD8+ T cells to investigate and enhance CD8+ T cell function. We will analyze the impact of CD4+ T cell priming on CD8+ T cells and compare various aLN formulations to optimize co-culture conditions. This will guide further optimization of conditions for effective co-culture of human CD4+ and CD8+ T cells. Finally, we will test the optimized aLN MPs in vivo, evaluating their ability to generate and expand antigen-specific T cells and assess their efficacy in B16 murine melanoma models. If successful, this approach will produce a novel acellular platform for in vivo generation of effective CD4+ T cell responses, with the ability to enhance immunotherapy outcomes.