Development of CAR-T therapy for Ewing sarcoma using zebrafish in vivo models
Ewing sarcoma (EwS) is a malignant cancer of bone and soft tissues that occurs mainly in children, adolescents and young adults. Currently, combinations of intensive chemotherapy, surgery and radiation are only 70% effective for localized tumors, and these therapies can cause lifelong health problems in survivors. If the tumors spread, fewer than 1/3 of patients will survive. New therapeutic advances are needed that are more effective with fewer toxic side effects. Recently, therapies that use the patient’s own immune system to attack cancer cells, such as CAR-T cell therapies, have been very effective for some childhood cancers such as leukemias. However, CAR-T therapy has not yet been effective for Ewing sarcoma. We believe that features of Ewing sarcoma tumor cells, and interaction of the cells with the surrounding non-tumor tissue, contributes to the failure of CAR-T therapy for this disease. To address the obstacles to CAR-T therapy in Ewing sarcoma, we will use zebrafish. The zebrafish system has a lot of advantages for this work: human Ewing sarcoma tumor cells and CAR-T cells can be implanted into large numbers of transparent fish larvae, and we can directly observe how the T cells attack the tumor cells, and how the cells can be engineered to be more effective. We also have the unique opportunity to generate Ewing sarcomas in the zebrafish, and to study effects of CAR-T cells in living animals with a fully intact immune system.
Project Goal:
The major goal of our project is to make effective CAR-T therapy an option for patients with Ewing sarcoma. CAR-T cells are engineered immune cells which are specifically targeted to cancer cells. We plan to rapidly test different types of CAR-T cells using the fish larval system. We will test whether a two-component (“gated”) CAR-T cell is more specific than a conventional CAR-T cell, and we will test strategies to make gated CAR-T cells more powerful and highly active in the presence of tumor cells. The practical goal of these experiments is to rapidly refine the CAR-T strategy to enable use of these improved CAR-T cells in the clinic as soon as possible. At the same time, we recognize that there may be features in the normal tissue surrounding a tumor (the “tumor microenvironment”) that render CAR-T cells ineffective. Until now, this question has been difficult to study because there was no animal model with an intact immune system that develops Ewing sarcoma. We have now developed such a model in zebrafish, and in part 2 of our proposal, we will use this system to look more deeply at how the tumor microenvironment affects the ability of CAR-T cells to eradicate Ewing sarcoma tumor cells. Our hope is that overcoming scientific and translational barriers to developing effective immunotherapy for Ewing sarcoma can significantly improve outcomes for Ewing sarcoma patients.
