Concomitant radiation therapy (RT) and temozolomide (TMZ) therapy after surgery is the standard treatment for glioblastoma multiforme (GBM). Radiation and chemotherapy can affect the immune system with implications on subsequent immune therapy. Therefore, we examined the phenotype and function of peripheral blood mononuclear cells in 25 patients with GBM prior to and 4 weeks after treatment with RT-TMZ using multicolor flow cytometry, as well as in vitro CD4(+) regulatory T cell (T(reg)) suppressor and dendritic cell maturation assays. RT-TMZ induced significant lymphopenia, with a decrease in total CD4(+) T cells, but did not significantly change monocyte counts. The proportion of functional T(reg) cells increased after treatment, whereas their absolute numbers remained stable. There was also a measurable decrease in the proportion of CD8(+)CD56(+) and absolute number of CD3(-)CD56(+) effector cells. Posttherapy monocytes retained the ability to mature into dendritic cells. Treatment with RT-TMZ is associated with changes in regulatory and effector peripheral blood mononuclear cells that tilt the balance towards an immune suppressive state. This shift can affect the outcome of immune therapy following RT-TMZ treatment and should be considered in the design of future combination therapy regimens.

A link between autoimmunity and improved antitumor immunity has long been recognized, although the exact mechanistic relationship between these two phenomena remains unclear. In the present study we have found that vitiligo, the autoimmune destruction of melanocytes, generates self antigen required for mounting persistent and protective memory CD8 + T cell responses to melanoma. Vitiligo developed in approximately 60% of mice that were depleted of regulatory CD4 + T cells and then subjected to surgical excision of large established B16 melanomas. Mice with vitiligo generated 10-fold larger populations of CD8 + memory T cells specific for shared melanoma/melanocyte antigens. CD8 + T cells in mice with vitiligo acquired phenotypic and functional characteristics of effector memory, suggesting that they were supported by ongoing antigen stimulation. Such responses were not generated in melanocyte-deficient mice, indicating a requirement for melanocyte destruction in maintaining CD8 + T cell immunity to melanoma. Vitiligo-associated memory CD8 + T cells provided durable tumor protection, were capable of mounting a rapid recall response to melanoma, and did not demonstrate phenotypic or functional signs of exhaustion even after many months of exposure to antigen. This work establishes melanocyte destruction as a key determinant of lasting melanoma-reactive immune responses, thus illustrating that immune-mediated destruction of normal tissues can perpetuate adaptive immune responses to cancer.

The generation of protective CD8

The complex molecular communications that occur between neoplastic and stromal cells within the tumor microenvironment play an integral role in breast cancer pathogenesis. Carcinoma-associated fibroblasts (CAF) produce tumor-enhancing factors and have been strongly implicated in breast cancer development. Similar to the way in which tumors have been compared with "wounds that never heal," CAFs have been equated to activated fibroblasts, which are present in inflammatory environments, in which they aid in wound healing through tissue remodeling and repair. Matrix metalloproteinase-1 (MMP-1) and G protein-coupled receptor, CXCR4, are elevated in these activated fibroblasts, in which they facilitate angiogenesis and matrix degradation, processes that are also vital to breast cancer metastasis. In this study, we investigated MMP-1 and CXCR4 expression in normal human mammary fibroblasts (HMF) exposed to soluble breast cancer factors. Historically, elevated CXCR4 expression is associated with breast cancer cells. However, we show that soluble factors secreted by SUM102 breast cancer cells stimulated the expression of MMP-1 and CXCR4 in HMFs. As a result, these stromal cells acquired an invasive and migratory phenotype. To confirm the clinical relevancy of our findings, we analyzed CAFs obtained from primary breast cancers. These cells also displayed elevated MMP-1 and CXCR4 levels compared with counterpart fibroblasts, and were more invasive and migratory. Together, our data suggest that soluble breast cancer factors initiate the transdifferentiation of normal HMFs to tumor-promoting CAFs, and that through the induction of MMP-1 and CXCR4 levels, these cells exhibit an invasive and migratory phenotype. (Mol Cancer Res 2009;7(7):1033-44)

Treatment of tumor-bearing mice with a stimulatory Ab to glucocorticoid-induced TNFR familyrelated receptor (GITR) has previously been shown to elicit protective T cell responses against poorly immunogenic tumors. However, the role of GITR stimulation on CD8 T cells and the nature of tumor rejection Ags have yet to be determined. In this study, we show that a stimulatory mAb to GITR (clone DTA-1) acts directly on CD8 T cells, but not on CD4 + CD25 + regulatory T (T reg ) cells, in B16 tumor-bearing mice to induce concomitant immunity against secondary B16 tumors, as well as protective memory following surgical excision of the primary tumor. Melanoma growth itself induced GITR expression on tumor-specific CD8 T cells, providing a mechanism whereby these cells may respond to stimulatory anti-GITR. Unexpectedly, in contrast to T reg cell depletion therapy with anti-CD4, GITR stimulation induced very weak CD8 T cell responses to melanocyte differentiation Ags expressed by the tumor, and did not induce autoimmune vitiligo. Accordingly, GITR-stimulated hosts that were primed with B16 melanoma rejected B16, but not the unrelated JBRH melanoma, indicating that tumor rejection Ags are tumor-specific rather than shared. In support of this, we show that GITR stimulation induces CD8 T cell responses to a tumor-specific Ag, and that these responses are of higher functional avidity compared with those induced by T reg cell depletion. We conclude that stimulation of GITR on effector CD8 T cells results in high-avidity T cell responses to tumor-specific Ags, thereby inducing potent antitumor immunity in the absence of auto-immunity.A major challenge of cancer immunotherapy has been the generation of antitumor immunity in the absence of autoimmunity. In addition to self-Ags, tumors express unique Ags that are derived from mutated proteins (1-3) and can serve as potent tumor-rejection Ags (4-6). Therapies that stimulate immunity against such tumor-specific Ags, rather than self-Ags, may provide more potent and durable antitumor immunity without eliciting autoimmunity (3,6,7). However, autoimmunity has been unavoidable when T cell responses are globally Address correspondence and reprint requests to Dr. Mary Jo Turk, Dartmouth Medical School, One Medical Center Drive, Lebanon, NH 03756. mary.jo.turk@dartmouth.edu. The online version of this article contains supplemental material. DisclosuresThe authors have no financial conflicts of interest. and nonspecifically induced by therapies such as CTLA-4 blockade and regulatory T (T reg ) cell depletion (8-10). NIH Public AccessThe glucocorticoid-induced TNFR family-related receptor (GITR) is a member of the costimulatory TNFR subfamily that is constitutively expressed on T reg cells and upregulated by CD8 and CD4 effector T cells upon activation (11,12). Treatment with agonistic anti-GITR (clone DTA-1) has been shown to induce rejection of highly immunogenic tumors (4,13), but it is markedly less effective against poorly immunogenic tumors. We have previously shown that GITR sti...

Antitumor immune responses can be stimulated by interfering with regulatory T-cell (T reg ) function. However, this effect is short lived unless T-cell memory to tumor antigens can be generated. Our recent studies show that T reg cells not only limit primary responses to tumor/self-antigens in tumorbearing hosts but also prevent the natural generation of T-cell memory to such antigens. Here, we discuss the role of T reg cells in suppressing T-cell memory after surgical excision of tumors and the potential clinical benefits of overcoming this suppression.

BackgroundWe have previously demonstrated that temporary depletion of CD4 T cells in mice with progressive B16 melanoma, followed by surgical tumor excision, induces protective memory CD8 T cell responses to melanoma/melanocyte antigens. We also showed that persistence of these CD8 T cells is supported, in an antigen-dependent fashion, by concurrent autoimmune melanocyte destruction. Herein we explore the requirement of CD4 T cell help in priming and maintaining this protective CD8 T cell response to melanoma.Methodology and Principal FindingsTo induce melanoma/melanocyte antigen-specific CD8 T cells, B16 tumor bearing mice were depleted of regulatory T cells (Treg) by either temporary, or long-term continuous treatment with anti-CD4 (mAb clone GK1.5). Total depletion of CD4 T cells led to significant priming of IFN-γ-producing CD8 T cell responses to TRP-2 and gp100. Surprisingly, treatment with anti-CD25 (mAb clone PC61), to specifically deplete Treg cells while leaving help intact, was ineffective at priming CD8 T cells. Thirty to sixty days after primary tumors were surgically excised, mice completely lacking CD4 T cell help developed autoimmune vitiligo, and maintained antigen-specific memory CD8 T cell responses that were highly effective at producing cytokines (IFN-γ, TNF-α, and IL-2). Mice lacking total CD4 T cell help also mounted protection against re-challenge with B16 melanoma sixty days after primary tumor excision.Conclusions and SignificanceThis work establishes that CD4 T cell help is dispensable for the generation of protective memory T cell responses to melanoma. Our findings support further use of CD4 T cell depletion therapy for inducing long-lived immunity to cancer.

Lymphocytes are a key component of the immune system and their differentiation and function are directly influenced by cancer. We examined peripheral blood lymphocyte (PBL) gene expression as a biomarker of illness and treatment effect using the Affymetrix Human Gene ST1 platform in patients with metastatic renal cell carcinoma (mRCC) who received combined treatment with IL-2, interferon-?-2a and dendritic cell vaccine. We examined gene expression, cytokine levels in patient serum and lymphocyte subsets as determined by flow cytometry (FCM). Pre-treatment PBLs from patients with mRCC exhibit a gene expression profile and serum cytokine profile consistent with inflammation and proliferation not found in healthy donors (HD). PBL gene expression from patients with mRCC showed increased mRNA of genes involved with T-cell and TREG-cell activation pathways, which was also reflected in lymphocyte subset distribution. Overall, PBL gene expression post-treatment (POST) was not significantly different than pre-treatment (PRE). Nevertheless, treatment related changes in gene expression (post-treatment minus pre-treatment) revealed an increased expression of T-cell and B-cell receptor signaling pathways in responding (R) patients compared to non-responding (NR) patients. In addition, we observed down-regulation of TREG-cell pathways post-treatment in R vs. NR patients. While exploratory in nature, this study supports the hypothesis that enhanced inflammatory cytotoxic pathways coupled with blunting of the regulatory pathways is necessary for effective anti-cancer activity associated with immune therapy. This type of analysis can potentially identify additional immune therapeutic targets in patients with mRCC.