Low Dose Radiation by Radiopharmaceutical Therapy Enhances GD2 TRAC- CAR T Cells Efficacy in Localized Neuroblastoma
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Background
While chimeric antigen receptor (CAR) T cells have achieved significant success against hematological malignancies, efficacy against neuroblastoma has been limited. Virus-free CRISPR-edited GD2 TRAC- CAR T cells have been developed as a potential means of improving CAR T efficacy but are not curative. Radiopharmaceutical therapy (RPT) is a promising approach to enhance the effectiveness of immunotherapies, including immune checkpoint inhibitors. However, it remains unclear whether RPT can synergize with GD2 TRAC- CAR T cells to improve outcomes in neuroblastoma.
Methods
Dosimetry studies were conducted to measure the absorbed radiation dose delivered by lutetium-177 ( 177 Lu) in both in vitro and in vivo models. Tumor-bearing mice were treated sequentially with low dose radiation by 177 Lu-NM600, an alkylphosphocholine mimetic radiopharmaceutical agent, followed 9 days later by GD2 TRAC- CAR T cells generated in a virus-free manner by CRISPR/Cas9. Tumor burden was monitored through bioluminescence imaging and tumor size measurements. Mechanistic studies were performed using flow cytometry, multiplex assay and single-cell proteomic analysis.
Results
Low dose radiation delivered by 177 Lu-NM600 synergized with GD2 TRAC- CAR T cells in a localized neuroblastoma model, resulting in complete tumor regression in all mice. The optimal combination was dependent on both the radiation dose and timing to minimize the negative impact of radiation on CAR T cell viability. Irradiation of neuroblastoma cells by low-dose RPT before GD2 TRAC- CAR T cells enhanced the release by CAR T cells of perforin, granzyme B and cytokines like TNF-α and IL-7 while abrogating TGF-β1 secretion. Additionally, low-dose RPT upregulated Fas on neuroblastoma cells, potentially enabling a CAR-independent killing.
Conclusions
This study demonstrates that low-dose RPT can enhance CAR T cell efficacy to treat a solid tumor. Findings suggest that optimization of radiation dose and timing may be needed for each patient and RPT to account for effects of varied tumor radiosensitivity and dosimetry.
