IFNG and neoplasm: We previously administered attIL12-T cells for treatment of osteosarcoma PDX tumors and found that the rich ECM structure throughout the entire tumor was impossible to penetrate.25 Although we demonstrated that the interaction between attIL12 from attIL12-T cells and CSV from tumor cells stimulates IFNγ production,23 obviously this IFNγ level was not enough to overcome the total collagen barrier in ECM-rich sarcoma tumors.