An in situ autologous tumor vaccination with combined radiation therapy and TLR9 agonist therapy.
OBJECTIVE
Recent studies have shown that a new generation of synthetic agonist of Toll-like receptor (TLR) 9 consisting a 3'-3'-attached structure and a dCp7-deaza-dG dinucultodie shows more potent immunostimulatory effects in both mouse and human than conventional CpG oligonucleotides. Radiation therapy (RT) provides a source of tumor antigens that are released from dying, irradiated, tumor cells without causing systemic immunosuppression. We, therefore, examined effect of combining RT with a designer synthetic agonist of TLR9 on anti-tumoral immunity, primary tumor growth retardation and metastases in a murine model of lung cancer.


METHODS
Grouped C57BL/6 and congenic B cell deficient mice (B(-/-)) bearing footpad 3LL tumors were treated with PBS, TLR9 agonist, control oligonucelotide, RT or the combination of RT and TLR9 agonist. Immune phenotype of splenocytes and serum IFN-γ and IL-10 levels were analyzed by FACS and ELISA, 24 h after treatment. Tumor growth, lung metastases and survival rate were monitored and tumor specific antibodies in serum and deposition in tumor tissue were measured by ELISA and immunofluorescence.


RESULTS
TLR9 agonist expanded and activated B cells and plasmacytoid dendritic cells in wild-type mice and natural killer DCs (NKDCs) in B cell-deficient (B(-/-)) mice bearing ectopic Lewis lung adenocarcinoma (3LL). Combined RT with TLR9 agonist treatment inhibited 3LL tumor growth in both wild type and B(-/-) mice. A strong tumor-specific humoral immune response (titer: 1/3200) with deposition of mouse IgG auto-antibodies in tumor tissue were found in wildtype mice, whereas the number of tumor infiltrating NKDCs increased in B(-/-) mice following RT+ TLR9 agonist therapy. Furthermore, mice receiving combination therapy had fewer lung metastases and a higher survival than single treatment cohorts.


CONCLUSIONS
Combination therapy with TLR9 agonist and RT induces systemic anti-tumoral humoral response, augments tumoral infiltration of NKDCs, reduces pulmonary metastases and improves survival in a murine model of 3LL cancer.
Department of Radiation Oncology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York, United States of America.
Huagang
H
Zhang
Laibin
L
Liu
Dong
D
Yu
Ekambar R
ER
Kandimalla
Hui Bin
HB
Sun
Sudhir
S
Agrawal
Chandan
C
Guha
D000230:Adenocarcinoma / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology / Q000532:radiotherapy*; D000077192:Adenocarcinoma of Lung; D000818:Animals; D000912:Antibodies, Neoplasm / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D018450:Disease Progression; D006801:Humans; D056747:Immunomodulation / Q000187:drug effects / Q000528:radiation effects; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D051379:Mice; D009362:Neoplasm Metastasis; D012008:Recurrence; D016019:Survival Analysis; D051217:Toll-Like Receptor 9 / Q000819:agonists*; D059016:Tumor Microenvironment / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D014611:Vaccination
D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D051217:Toll-Like Receptor 9