Abstract 6167: Modeling the impact of chemotherapy and small molecule inhibitors on the 3D microenvironment of pediatric bone sarcomas

Abstract One of the main types of pediatric sarcomas is primary bone sarcoma (PBS) where the sarcoma initially occurs in the bone matrix. PBS includes osteosarcoma and Ewing sarcoma, both of which are primarily seen in pediatric populations. Treatment for osteosarcoma often includes amputation or limb salvaging surgery, along with pre- and post-operative chemotherapy, both of which are significant surgeries for adolescents. These surgeries can significantly limit their long-term mobility, altering their quality of life. These sarcomas produce osteoid and a porous, mineralized matrix like that of native bone tissue. In this work, we have designed pediatric sarcoma 3D cell culture models by creating custom hydrogel materials to match the ECM properties of bone sarcomas such as osteosarcoma and Ewing sarcoma. We refined the composition of this material using nanoscale mechanobiology analysis to assess the nanoscale stress, strain, compression, and Young’s modulus to match the mechanical properties of the native bone sarcoma ECM. We have cultured organoids in this material using imaging to track and quantify the ECM remodeling by the 3D culture tumor model. Like what is seen in literature we have found that with tumor proliferation and progression comes increased collagen, collagen remodeling for increased mechanical stiffness, and overall ECM stiffness increased to create a denser, mechanically stiffer tumor. We hypothesize that chemotherapies and small molecule inhibitors may be able to weaken the dense tumor formation and ECM remodeling seen in our 3D cell culture models as the drugs penetrate through the hydrogel induce apoptosis in the cells and lead to a decrease in ECM components and cell-matrix bonding. Both AKT and proteasome inhibitors block the pathways associated with collagen type I, III, and IV driving tumor progression through the pERK and PI3K/AKT pathways. The goal is to test these targeted therapies on our sarcoma 3D cell culture models to see if they would then slow or inhibit the effects of collagen on driving tumor growth and progression in pediatric solid tumors where collagen plays such a vital role. Additionally, in immune “cold” tumors such as Ewing sarcoma collagen functions as an important immunosuppressive signaling molecule so inhibiting collagen in signaling helps to turn Ewing sarcoma and other pediatric sarcomas into more immune “hot” tumors by taking away the role collagen plays in keeping this an immune “cold” tumor. We anticipate our novel 3D culture models can model the complex relationships between tumor, microenvironment, and therapeutic response. Citation Format: Allison Haley Reno, Joshua Kelley, Reid Barker, Jamie Silverman, Jack Hyland, Cameron Bumbleburg, Elizabeth Maahs, Anna Tingler, Denis C. Guttridge, Melinda A. Engevik, Yongren Wu, Casey Langdon. Modeling the impact of chemotherapy and small molecule inhibitors on the 3D microenvironment of pediatric bone sarcomas abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6167.