Analysis of gene expression in SKBR3 cells isolated from xenograft tumors in mice treated with radioinducible TNF producing CAR-T cells

Adoptive CAR T cell therapies have limited efficacy in solid tumors due to poor infiltration and impaired effector function, while radiotherapy is constrained by tumor radio resistance and metastatic spread. To overcome these limitations, we developed a strategy that integrates the spatial precision of ionizing radiation with the biological specificity of CAR T cells. We identified radiation-induced genes from irradiated intratumoral T cells and engineered synthetic radio inducible promoters to drive expression of a prototype effector, TNF. Human CAR T cells expressing this construct (riTNF CAR T) secreted high levels of TNF upon irradiation, independently of antigen engagement. In in vivo models of HER2⁺ and FRα⁺ human xenograft tumors, the combination of riTNF CAR T cells with local irradiation resulted in significantly greater tumor regression than either treatment alone or the combination of standard CAR T cells with irradiation. To study the antitumoral mechanisms involved in treatment with riTNF CAR-T cells, we sorted cancer cells from xenograft tumors after treatment and analyzed changes in gene expression caused by riTNF CAR-T therapy vs control treatments.