%0 Journal Article
%T Enhancing radiotherapy response via intratumoral injection of a TLR9 agonist in autochthonous murine sarcomas.
%A Su C
%A Kent CL
%A Pierpoint M
%A Floyd W
%A Luo L
%A Williams NT
%A Ma Y
%A Peng B
%A Lazarides AL
%A Subramanian A
%A Himes JE
%A Perez VM
%A Hernansaiz-Ballesteros RD
%A Roche KE
%A Modliszewski JL
%A Selitsky SR
%A Shinohara ML
%A Wisdom AJ
%A Moding EJ
%A Mowery YM
%A Kirsch DG
%J JCI Insight
%V 9
%N 14
%D 2024 Jun 13
%M 39133651
%F 9.484
%R 10.1172/jci.insight.178767
%X Radiation therapy (RT) is frequently used to treat cancers, including soft-tissue sarcomas. Prior studies established that the toll-like receptor 9 (TLR9) agonist cytosine-phosphate-guanine oligodeoxynucleotide (CpG) enhances the response to RT in transplanted tumors, but the mechanisms of this enhancement remain unclear. Here, we used CRISPR/Cas9 and the chemical carcinogen 3-methylcholanthrene (MCA) to generate autochthonous soft-tissue sarcomas with high tumor mutation burden. Treatment with a single fraction of 20 Gy RT and 2 doses of CpG significantly enhanced tumor response, which was abrogated by genetic or immunodepletion of CD8+ T cells. To characterize the immune response to CpG+RT, we performed bulk RNA-Seq, single-cell RNA-Seq, and mass cytometry. Sarcomas treated with 20 Gy and CpG demonstrated increased CD8 T cells expressing markers associated with activation and proliferation, such as Granzyme B, Ki-67, and IFN-γ. CpG+RT also upregulated antigen presentation pathways on myeloid cells. Furthermore, in sarcomas treated with CpG+RT, TCR clonality analysis suggests an increase in clonal T cell dominance. Collectively, these findings demonstrate that CpG+RT significantly delays tumor growth in a CD8 T cell-dependent manner. These results provide a strong rationale for clinical trials evaluating CpG or other TLR9 agonists with RT in patients with soft-tissue sarcoma.