Treatment of mammary carcinomas in HER-2 transgenic mice through combination of genetic vaccine and an agonist of Toll-like receptor 9.
OBJECTIVE
Oligodeoxynucleotides containing unmethylated CpG dinucleotides induce innate and adaptive immunity through Toll-like receptor 9 (TLR9). In the present study, we have examined the ability of a novel agonist of TLR9, called immunomodulatory oligonucleotide (IMO), to enhance effects of a HER-2/neu plasmid DNA electroporation/adenovirus (DNA-EP/Ad) vaccine.


METHODS
BALB/NeuT mice were treated with DNA-EP vaccine alone, IMO alone, or the combination of two agents starting at week 13, when all mice showed mammary neoplasia. Tumor growth and survival were documented. Antibody and CD8+ T-cell responses were determined. Peptide microarray analysis of sera was carried out to identify immunoreactive epitopes. Additionally, microCT and microPET imaging was carried out in an advanced-stage tumor model starting treatment at week 17 in BALB/NeuT mice.


RESULTS
The combination of DNA-EP and IMO resulted in significant tumor regression or delay to tumor progression. 2-Deoxy-2-[18F]fluoro-D-glucose microPET and microCT imaging of mice showed reduced tumor size in the DNA-EP/IMO combination treatment group. Mice treated with the combination produced greater antibody titers with IgG2a isotype switch and antibody-dependent cellular cytotoxicity activity than did mice treated with DNA-EP vaccine. An immunogenic B-cell linear epitope, r70, within the HER-2 dimerization domain was identified through microarray analysis. Heterologous DNA-EP/Ad vaccination combined with IMO increased mice survival.


CONCLUSIONS
The combination of HER-2/neu genetic vaccine and novel agonist of TLR9 had potent antitumor activity associated with antibody isotype switch and antibody-dependent cellular cytotoxicity activities. These results support possible clinical trials of the combination of DNA-EP/Ad-based cancer vaccines and IMO.
Aurisicchio
Luigi
L
Istituto di Ricerche di Biologia Molecolare, Oncology/Functional Department, Merck Research Labs, Rome, Italy. luigi_aurisicchio@merck.com
Peruzzi
Daniela
D
Conforti
Antonella
A
Dharmapuri
Sridhar
S
Biondo
Antonella
A
Giampaoli
Saverio
S
Fridman
Arthur
A
Bagchi
Ansu
A
Winkelmann
Christopher T
CT
Gibson
Raymond
R
Kandimalla
Ekambar R
ER
Agrawal
Sudhir
S
Ciliberto
Gennaro
G
La Monica
Nicola
N
D000256:Adenoviridae / Q000235:genetics; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000920:Antibody-Dependent Cell Cytotoxicity; D000938:Antigen-Presenting Cells / Q000276:immunology; D003131:Combined Modality Therapy; D004247:DNA / Q000008:administration & dosage; D019281:Dimerization; D018274:Electroporation; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D018664:Interleukin-12 / Q000378:metabolism; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000235:genetics / Q000276:immunology* / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D010957:Plasmids / Q000008:administration & dosage*; D049268:Positron-Emission Tomography; D051381:Rats; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology*; D051217:Toll-Like Receptor 9 / Q000502:physiology*; D019444:Vaccines, DNA / Q000627:therapeutic use*
D000469:Alkaline Phosphatase; D004247:DNA; D018664:Interleukin-12; D010446:Peptide Fragments; D018719:Erb-b2 Receptor Tyrosine Kinases; D051217:Toll-Like Receptor 9; D019444:Vaccines, DNA; C495370:Tlr9 protein, mouse