Blockade of TGF-β signaling to enhance the antitumor response is accompanied by dysregulation of the functional activity of CD4

BACKGROUND: The pleiotropic cytokine, transforming growth factor (TGF)-β, and CD4 METHODS: Using BALB/c, FoxP3eGFP and Rag RESULTS: SM16 abrogates TGF-β-induced Treg generation in vitro but does not prevent global homeostatic expansion of CD4 CONCLUSIONS: These findings suggest that blockade of TGF-β signaling is a potentially useful strategy for blunting Treg function to enhance the anti-tumor response. Our data further suggest that the overall dampening of Treg function may involve the expansion of a quiescent Treg precursor population, which is CD

Reverting Immune Suppression to Enhance Cancer Immunotherapy.

Tumors employ strategies to escape immune control. The principle aim of most cancer immunotherapies is to restore effective immune surveillance. Among the different processes regulating immune escape, tumor microenvironment-associated soluble factors, and/or cell surface-bound molecules are mostly responsible for dysfunctional activity of tumor-specific CD

Enhancement of anti-tumor efficacy of immune checkpoint blockade by alpha-TEA.

Cancer immunotherapy such as anti-PD-1/anti-PD-L1 immune checkpoint blockade (ICB) can provide significant clinical benefit in patients with advanced malignancies. However, most patients eventually develop progressive disease, thus necessitating additional therapeutic options. We have developed a novel agent, a-TEA-LS, that selectively induces tumor cell death while sparing healthy tissues, leading to increased activation of tumor-reactive T cells and tumor regression. In the current study, we explored the impact of combined a-TEA-LS + ICB in orthotopic and spontaneously arising murine models of mammary carcinoma. We found that a-TEA-LS + ICB led to increased production of pro-inflammatory cytokines that were associated with a reduction in tumor growth and prolonged survival. Together, these data demonstrate the potential utility of a-TEA-LS + ICB for the treatment of breast cancer and provide the rationale for clinical translation of this novel approach

Blockade of TGF-β signaling to enhance the antitumor response is accompanied by dysregulation of the functional activity of CD4+CD25+Foxp3+ and CD4+CD25−Foxp3+ T cells

The pleiotropic cytokine, transforming growth factor (TGF)-β, and CD4+CD25+Foxp3+ regulatory T cells (Tregs) play a critical role in actively suppressing antitumor immune responses. Evidence shows that TGF-β produced by tumor cells promotes tolerance via expansion of Tregs. Our group previously demonstrated that blockade of TGF-β signaling with a small molecule TGF-β receptor I antagonist (SM16) inhibited primary and metastatic tumor growth in a T cell dependent fashion. In the current study, we evaluated the effect of SM16 on Treg generation and function. Using BALB/c, FoxP3eGFP and Rag−/− mice, we performed FACS analysis to determine if SM16 blocked de novo TGF-β-induced Treg generation in vitro and in vivo. CD4+ T cells from lymph node and spleen were isolated from control mice or mice maintained on SM16 diet, and flow cytometry analysis was used to detect the frequency of CD4+CD25−FoxP3+ and CD4+CD25+FoxP3+ T cells. In vitro suppression assays were used to determine the ability to suppress naive T cell proliferation in vitro of both CD4+CD25+FoxP3+ and CD4+CD25−FoxP3+ T cell sub-populations. We then examined whether SM16 diet exerted an inhibitory effect on primary tumor growth and correlated with changes in FoxP3+expression. ELISA analysis was used to measure IFN-γ levels after 72 h co-culture of CD4+CD25+ T cells from tumor-bearing mice on control or SM16 diet with CD4+CD25− T cells from naive donors. SM16 abrogates TGF-β-induced Treg generation in vitro but does not prevent global homeostatic expansion of CD4+ T cell sub-populations in vivo. Instead, SM16 treatment causes expansion of a population of CD4+CD25−Foxp3+ Treg-like cells without significantly altering the overall frequency of Treg in lymphoreplete naive and tumor-bearing mice. Importantly, both the CD4+CD25−Foxp3+ T cells and the CD4+CD25+Foxp3+ Tregs in mice receiving SM16 diet exhibited diminished ability to suppress naive T cell proliferation in vitro compared to Treg from mice on control diet. These findings suggest that blockade of TGF-β signaling is a potentially useful strategy for blunting Treg function to enhance the anti-tumor response. Our data further suggest that the overall dampening of Treg function may involve the expansion of a quiescent Treg precursor population, which is CD4+CD25−Foxp3+.Other Information Published in: Journal of Translational Medicine License: http://creativecommons.org/licenses/by/4.0/See article on publisher's website: http://dx.doi.org/10.1186/s12967-019-1967-3</p