Abstract 4282: Crosstalk between the immune system and the extracellular matrix in the context of melanoma and aging

Abstract Aging is an independent prognostic factor for the diagnosis of melanoma. The extracellular matrix of the skin has well-documented changes with age, such as the loss of HAPLN1, which can lead to differential metastasis in aged individuals. The aged microenvironment can contribute to the phenotype switch, where aged individuals have smaller primary tumors but more metastases, i.e., going instead of growing. The extracellular matrix (ECM) has been shown to modulate the immune response either through direct binding of ECM proteins or through mechanotransduction, but it is unclear how aging affects this crosstalk. Our hypothesis is that the ECM can modulate immune response to melanoma and affect response to immune checkpoint blockade (ICB) therapy. Melanoma cells cultured on cell derived matrices (CDMs) from young and aged human fibroblasts show differential levels of expression of PD-L1, a ligand that binds to PD-1 on T cells to induce T cell exhaustion. Antibodies targeting PD-1/PD-L1 are one of the main ICB treatments available to melanoma. We are also investigating T cell motility on young and aged CDMs, as well as correlating T cell infiltration in murine tumors with ECM signatures as identified by second harmonic generation microscopy. Therefore, we have compiled evidence that aging affects the crosstalk between the extracellular matrix and the immune system, providing a new horizon for therapeutic improvement of response in older patients. Citation Format: Elizabeth I. Harper, Yash Chhabra, Alexis Carey, Murilo Ramos Rocha, Laura Hüser, Vania Wang, Agrani Dixit, Ashani Weeraratna. Crosstalk between the immune system and the extracellular matrix in the context of melanoma and aging [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4282.