Several lines of investigation have revealed the apparent interplay between the immune system of the host and many conventional, “standard-of-care” anticancer therapies, including chemotherapy and small molecule targeted therapeutics. In particular, preclinical and clinical studies have demonstrated the important role of regulatory T cells (Tregs) in inhibiting immune responses elicited by immunotherapeutic regimens such as those based on anticancer vaccines or checkpoint inhibitors. However, how the number and immunosuppressive function of Tregs change in cancer patients undergoing treatment with non-immune anticancer therapies remains to be precisely elucidated. To determine whether immunostimulatory therapies can be employed successfully in combination with conventional anticancer regimens, we have investigated both the number and function of Tregs obtained from the peripheral blood of carcinoma patients before the initiation and during the course of chemotherapeutic and targeted agent regimens. Our studies show that the treatment of breast cancer patients with tamoxifen plus leuprolide, a gonadotropin releasing hormone agonist, has minimal effects on Tregs, while sunitinib appears to exert differential effects on Tregs among patients with metastatic renal carcinoma. However, the administration of docetaxel to patients with metastatic prostate or breast cancer, as well as that of cisplatin plus vinorelbine to non-small cell lung cancer patients, appears to significantly increase the ratio between effector T cells and Tregs and to reduce the immunosuppressive activity of the latter in the majority of patients. These studies provide the rationale for the selective use of active immunotherapy regimens in combination with specific standard-of-care therapies to achieve the most beneficial clinical outcome among carcinoma patients.

Small molecule BCL-2 inhibitors are being examined as monotherapy in phase I/II clinical trials for several types of tumors. However, few data are available about the effect of BCL-2 inhibitors on immune function. The aims of our study were to investigate the effect of a small molecule BCL-2 inhibitor on immune function and determine the most effective way of combining this inhibitor with a recombinant vaccine to treat tumors. The in vitro effect of the pan-BCL-2 inhibitor GX15-070 was assessed in mouse CD8 T lymphocytes at 2 different stages of activation as well as regulatory T lymphocytes (Treg). The in vivo effect of GX15-070 after recombinant vaccinia/fowlpox CEA-TRICOM vaccination was analyzed in tumor-infiltrating lymphocytes, and in splenocytes of mice bearing subcutaneous tumors. The therapeutic efficacy of such sequential therapy was measured as a reduction of pulmonary tumor nodules. Activated mature CD8 T lymphocytes were more resistant to GX15-070 as compared to early-activated cells. Treg function was significantly decreased after treatment with the BCL-2 inhibitor. In vivo, GX15-070 was given after vaccination so as to not negatively impact the induction of vaccine-mediated immunity, resulting in increased intratumoral activated CD8:Treg ratio and significant reduction of pulmonary tumor nodules. Our study is the first to show the effect of a small molecule BCL-2 inhibitor on the immune system and following a vaccine. It is also the first to demonstrate the efficacy of this sequence in reducing tumors in mouse models, providing a rationale for the design of combinational clinical studies.The current goal of vaccine therapy is to generate antigenspecific immunity to cancer cells to enhance immune-mediated destruction of tumors. Preclinical and clinical studies have shown that cancer vaccines carrying tumor-associated antigens (TAAs) can induce and enhance immune response against those antigens.1,2 The use of therapeutic cancer vaccines in combination with other cancer therapies offers a new paradigm that may yet lead to vaccines being used to treat several types of cancer. 3 There has also been increasing use of targeted small molecule inhibitors in the treatment of many tumor types. 2,4-10Approaches that alter the balance between prosurvival and prodeath BCL-2 family members have shown potential benefit in preclinical cancer models.11,12 Nonetheless, few data are available about the effect of small molecule BCL-2 inhibitors on immune function. We hypothesize that modulating the sensitivity of effector cells to the small molecule pan-BCL-2 inhibitor GX15-070 could change the balance between cancer cells and immune-effector cells, resulting in greater antitumor immune activity. GX15-070 is a synthetic derivative of bacterial prodiginines belonging to the polypirrole class of molecules. 13 It is a BH3-only mimetic molecule classified as a pan-BCL-2 inhibitor because of its ability to bind all antiapoptotic BCL-2 family members, including BCL-2, BCLxL, BCL-w, MCL-1 and BAK.14 GX15-070 has been shown t...

c‐Abl function is strictly dependent on its subcellular localization. Using an in vitro approach, we identify c‐Abl as a new substrate for p300, CBP (CREB‐binding protein) and PCAF (p300/CBP‐associated factor) histone acetyltransferases. Remarkably, acetylation markedly alters its subcellular localization. Point mutagenesis indicated that Lys 730, located in the second nuclear localization signal, is the main target of p300 activity. It has previously been reported that c‐Abl accumulates in the cytoplasm during myogenic differentiation. Here, we show that c‐Abl protein is acetylated at early stages of myogenic differentiation. Indeed, acetylation on Lys 730 drives c‐Abl accumulation in the cytoplasm and promotes differentiation. Thus, Lys 730 acetylation is a novel post‐translational modification of c‐Abl and a novel mechanism for modulating its subcellular localization that contributes to myogenic differentiation.

Ataxia telangiectasia (A-T) is a rare cancer-predisposing genetic disease, caused by the lack of functional ATM kinase, a major actor of the double strand brakes (DSB) DNA-damage response. A-T patients show a broad and diverse phenotype, which includes an increased rate of lymphoma and leukemia development. Fas-induced apoptosis plays a fundamental role in the homeostasis of the immune system and its defects have been associated with autoimmunity and lymphoma development. IntroductionAtaxia telangiectasia (A-T) is an autosomal recessive disorder characterized by cerebellar progressive neurodegeneration leading to ataxia, dilatation of blood vessels in the eye and facial area (telangiectasia), sensitivity to ␥-irradiation, high incidence of tumorigenesis in the lymphoid system, and deficiency in immunoresponses. A-T pathology is characterized by the loss of functional ATM protein kinase. Following DNA damage, ATM is rapidly activated and (auto)phosphorylated, 1 and, in turn, it phosphorylates a number of substrates that all contribute to cell growth arrest or, alternatively, apoptosis (reviewed in Shiloh 2 ). The higher cancer predisposition of A-T patients has been associated with the lack of DNA-damage response, which results in genomic instability. 3 The immune system is the major target of tumor development in these patients, and lymphoma and leukemia are very frequent. 4,5 This clinical feature is consistent with the central role of ATM in the management of the DNA DSBs generated during the immune system development and function in physiological conditions. 6 Indeed most of the lymphomas developed in A-T patients are characterized by aberrant VDJ recombination. 6 More interestingly, ATM expression is aberrantly low in several B-and T-cell lymphomas irrespective of A-T genotype. [7][8][9][10] Fas (CD95/APO-1) is a transmembrane protein belonging to the tumor necrosis factor superfamily. Upon binding of Fas ligand or agonistic antibodies, the Fas receptor recruits several cytosolic proteins to form the death-inducing signaling complex (DISC). This is necessary to catalyze dimerization and processing of procaspase-8 to generate the active caspase-8 tetramer, composed of 2 p18 and 2 p10 subunits, which initiates the caspase cascade. 11 activation is absolutely required to trigger receptoractivated apoptotic response, 12 and its catalytic activity has to be tightly regulated to avoid inappropriate activation and undesired cell death. 13 FLIP protein is structurally similar to procaspase-8 and can therefore compete with procaspase-8 for binding to DISC, thus preventing caspase-8 activation and the following apoptotic cascade. Two isoforms of FLIP, arising from alternative splicing, are normally present in most of the cells. FLIP-long (FLIP-L), similarly to procaspase-8, has 2 DED domains that mediate the recruitment to the DISC, as well as a p18 and a p10 subunit, but it lacks the Cys residue in the active site and is therefore catalytically impaired. However, in some contexts FLIP-L can also dimerize and theref...

This study demonstrates that CD8+ T cells in the tumor microenvironment display reduced functionality and hyporesponsiveness. TGF-β contributed markedly to the tumor-infiltrating CD8+ T cells’ (TILs) reduced functionality, which could be reversed using a small molecule TGF-β inhibitor. Upon T-cell receptor (TCR) activation, the activation of ITK and ERK kinases were reduced in CD8+ TILs, as compared to splenic CD8+ T cells: TGF-β inhibitor could reverse this phenomenon. This study demonstrates for the first time the association of the Spred-1 gene, an inhibitor of the Ras/MAPK pathway, with CD8+ TILs and TGF-β activity. Spred-1 was upregulated in CD8+ TILs and TGF-β enhanced the expression of Spred-1 in effector/memory CD8+ T cells and not in rested/memory CD8+ T cells. Based on these findings, this study supports the hypothesis that TGF-β mediates an inhibitory mechanism on CD8+ TILs involving TCR-signaling blockade and the upregulation of Spred-1, thus implicating Spred-1 as a potential new target for future anti-tumor immune studies.

We compared the effects of yeast-treated human dendritic cells (DCs) with CD40L-matured human DCs for the induction of effector cells and the number and functionality of CD4+CD25+CD127− FoxP3+ regulatory T cells (Tregs). DCs were treated with yeast or CD40L and cocultured with isolated autologous CD4+ T cells. CD4+CD25+CD127− T cells isolated from the coculture of CD4+ T cells plus yeast-treated DCs (yeast coculture) had a lower expression of FoxP3 and decreased suppressive function compared to CD4+CD25+CD127− T cells isolated from the coculture of CD4+ T cells plus CD40L-treated DCs (CD40L coculture). Also, compared to the CD40L coculture, the yeast coculture showed increases in the ratio of CD4+CD25+ activated T cells to Tregs and in the production of Th1-related cytokines (IL-2, TNF-α, IFN-γ) and IL-6. In addition, yeast-treated DCs used as antigen-presenting cells (APCs) incubated with the tumor antigen CEA enhanced the proliferation of CEA-specific CD4+ T cells compared to the use of CD40L-matured DCs used as APCs. This is the first study to report on the role of yeast-treated/matured human DCs in reducing Treg frequency and functionality and in enhancing effector to Treg ratios. These results provide an additional rationale for the use of yeast as a vector in cancer vaccines.

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