Oncostatin-M ligand-based CAR-T therapy displays robust anti-tumor activity against osteosarcoma.

backgroundCAR-T therapy has revolutionized treatments for many hematologic malignancies, but it has shown far less efficacy against solid tumors. One reason for this lower efficacy in solid tumors is increased antigen heterogeneity. This study utilizes a ligand-based CAR-T approach, which allows targeting of multiple receptors by a single ligand. A high expression of the ligand oncostatin M's (OSM) receptors, oncostatin M receptor (OSMR), and/or leukemic inhibitory factor receptor (LIFR) were noted in osteosarcoma cell lines and patient samples. Osteosarcoma is a bone cancer where treatment options have been stagnant for close to 40 years. Thus, this study explores the therapeutic potential of OSM ligand-based CAR-T cells against osteosarcoma.

methodsThird-generation CAR-T cells expressing human OSM on their surface were created, with the surface expression of OSM confirmed by flow cytometry. Co-incubation of OSM CARs and osteosarcoma in vitro was performed, with cell death assessed via Incucyte and PI detection by flow cytometry. CAR-Ts were injected i.v. into mice with osteosarcoma cell line xenografts, and metastatic osteosarcoma. New patient-derived samples were tested for OSMR and LIFR expression and vulnerability to OSM CAR T cells. A new PDX model (named KKOS) from a patient with metastatic treatment-resistant osteosarcoma was characterized and tested for its susceptibility to OSM CAR T cells. All cytotoxic in vivo experiments were performed with n=3-6 mice per group per experiment.

resultsOSM-CAR-T cells displayed cytotoxicity against osteosarcoma cell lines and patient samples expressing either one of OSM's receptors in vitro and in vivo. Large increases in cytokine release, specifically IFNγ, were noted in a target-specific manner. One injection of OSM-CAR-T cells intravenously reduced tumor burden in two different mouse xenograft models. A similar anti-tumor effect was also noted in a metastatic model and a mouse model with multiple implanted KKOS tumors.

conclusionsHuman ligand-based OSM CAR-T cells displayed anti-tumor effects against multiple osteosarcoma cell lines and patient samples. These effects were demonstrated in vitro, in xenograft models, and against a model simulating metastatic disease. Overall, this data supports the continued study of OSM-CAR-T cells as a new therapeutic avenue for osteosarcoma.