Systemic inhibition of transforming growth factor-beta in glioma-bearing mice improves the therapeutic efficacy of glioma-associated antigen peptide vaccines.
OBJECTIVE
A variety of cancers, including malignant gliomas, overexpress transforming growth factor-beta (TGF-beta), which helps tumors evade effective immune surveillance through a variety of mechanisms, including inhibition of CD8(+) CTLs and enhancing the generation of regulatory T (T(reg)) cells. We hypothesized that inhibition of TGF-beta would improve the efficacy of vaccines targeting glioma-associated antigen (GAA)-derived CTL epitopes by reversal of immunosuppression.


METHODS
Mice bearing orthotopic GL261 gliomas were treated systemically with a TGF-beta-neutralizing monoclonal antibody, 1D11, with or without s.c. vaccinations of synthetic peptides for GAA-derived CTL epitopes, GARC-1 (77-85) and EphA2 (671-679), emulsified in incomplete Freund's adjuvant.


RESULTS
Mice receiving the combination regimen exhibited significantly prolonged survival compared with mice receiving either 1D11 alone, GAA vaccines alone, or mock treatments alone. TGF-beta neutralization enhanced the systemic induction of antigen-specific CTLs in glioma-bearing mice. Flow cytometric analyses of brain-infiltrating lymphocytes revealed that 1D11 treatment suppressed phosphorylation of Smad2, increased GAA-reactive/IFN-gamma-producing CD8(+) T cells, and reduced CD4(+)/FoxP3(+) T(reg) cells in the glioma microenvironment. Neutralization of TGF-beta also upregulated plasma levels of interleukin-12, macrophage inflammatory protein-1 alpha, and IFN-inducible protein-10, suggesting a systemic promotion of type-1 cytokine/chemokine production. Furthermore, 1D11 treatment upregulated plasma interleukin-15 levels and promoted the persistence of GAA-reactive CD8(+) T cells in glioma-bearing mice.


CONCLUSIONS
These data suggest that systemic inhibition of TGF-beta by 1D11 can reverse the suppressive immunologic environment of orthotopic tumor-bearing mice both systemically and locally, thereby enhancing the therapeutic efficacy of GAA vaccines.
Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Ryo
R
Ueda
Mitsugu
M
Fujita
Xinmei
X
Zhu
Kotaro
K
Sasaki
Edward R
ER
Kastenhuber
Gary
G
Kohanbash
Heather A
HA
McDonald
Jay
J
Harper
Scott
S
Lonning
Hideho
H
Okada
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D057134:Antibodies, Neutralizing / Q000276:immunology; D000951:Antigens, Neoplasm; D001932:Brain Neoplasms / Q000276:immunology* / Q000628:therapy*; D019496:Cancer Vaccines; D045744:Cell Line, Tumor; D018984:Epitopes, T-Lymphocyte; D005910:Glioma / Q000276:immunology* / Q000628:therapy*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D016212:Transforming Growth Factor beta / Q000276:immunology*; D022223:Vaccines, Subunit / Q000627:therapeutic use*
D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D018984:Epitopes, T-Lymphocyte; D016212:Transforming Growth Factor beta; D022223:Vaccines, Subunit