Vile, Richard G.

AbstractA close connectivity between autoimmune and tumor rejection responses is known to exist in the case of melanoma immunotherapy. However, relatively little is known about self-antigens on other types of normal cells, their relation to the development of autoimmune disease, and their possible coexistence as potential tumor rejection antigens on associated tumors. In the current study, we induced inflammatory killing of normal prostate tissue in situ using a fusogenic membrane glycoprotein along with the immune adjuvant hsp70. We show here that, in the prostate, hsp70 induces interleukin (IL)-6, which triggers a CD4- and CD8-dependent progressive autoimmune reactivity, associated with IL-17 expression. This autoimmune response was also able to induce the rejection of established prostate tumors, but not other histologic types of tumors, growing elsewhere in the animal. These data show that the intimate connectivity between autoimmune and tumor rejection responses extends beyond the classic melanoma paradigm and may be clinically valuable for the treatment of established metastatic disease of the prostate. [Cancer Res 2007;67(24):11970–9]

AbstractRelatively little attention has been paid to the role of virotherapy in promoting antitumor immune responses. Here, we show that CD8+ T cells are critical for the efficacy of intratumoral vesicular stomatitis virus virotherapy and are induced against both virally encoded and tumor-associated immunodominant epitopes. We tested three separate immune interventions to increase the frequency/activity of activated antitumoral T cells. Depletion of Treg had a negative therapeutic effect because it relieved suppression of the antiviral immune response, leading to early viral clearance. In contrast, increasing the circulating levels of tumor antigen–specific T cells using adoptive T cell transfer therapy, in combination with intratumoral virotherapy, generated significantly improved therapy over either adoptive therapy or virotherapy alone. Moreover, the incorporation of a tumor-associated antigen within the oncolytic vesicular stomatitis virus increased the levels of activation of naïve T cells against the antigen, which translated into increased antitumor therapy. Therefore, our results show that strategies which enhance immune activation against tumor-associated antigens can also be used to enhance the efficacy of virotherapy. [Cancer Res 2007;67(6):2840–7]

AbstractAdoptive T-cell transfer has achieved significant clinical success in advanced melanoma. However, therapeutic efficacy is limited by poor T-cell survival after adoptive transfer and by inefficient trafficking to tumor sites. Here, we report that intratumoral expression of the chemokine CCL21 enhances the efficacy of adoptive T-cell therapy in a mouse model of melanoma. Based on our novel observation that CCL21 is highly chemotactic for activated OT-1 T cells in vitro and down-regulates expression of CD62L, we hypothesized that tumor cell–mediated expression of this chemokine might recruit, and retain, adoptively transferred T cells to the sites of tumor growth. Mice bearing metastatic tumors stably transduced with CCL21 survived significantly longer following adoptive T-cell transfer than mice bearing non–CCL21-expressing tumors. However, although we could not detect increased trafficking of the adoptively transferred T cells to tumors, tumor-expressed CCL21 promoted the survival and cytotoxic activity of the adoptively transferred T cells and led to the priming of antitumor immunity following T-cell transfer. To translate these observations into a protocol of real clinical usefulness, we showed that adsorption of a retrovirus encoding CCL21 to OT-1 T cells before adoptive transfer increased the therapeutic efficacy of a subsequently administered dose of OT-1 T cells, resulting in cure of metastatic disease and the generation of immunologic memory in the majority of treated mice. These studies indicate a promising role for CCL21 in enhancing the therapeutic efficacy of adoptive T-cell therapy. [Cancer Res 2007;67(1):300–8]

AbstractWe have reported that i.d. injection of plasmids encoding hsp70 and a suicide gene transcriptionally targeted to melanocytes generates specific proinflammatory killing of melanocytes. The resulting CD8+ T cell response eradicates systemically established B16 tumors. Here, we studied the consequences of that CD8+ T cell response on the phenotype of preexisting tumor. In suboptimal protocols, the T cell response selected B16 variants, which grow extremely aggressively, are amelanotic and have lost expression of the tyrosinase and tyrosinase-related protein 2 (TRP-2) antigens. However, expression of other melanoma-associated antigens, such as gp100, was not affected. Antigen loss could be reversed by long-term growth in culture away from immune-selective pressures or within 96 hours by treatment with the demethylating agent 5-azacytidine (5-Aza). When transplanted back into syngeneic animals, variants were very poorly controlled by further vaccination. However, a combination of vaccination with 5-Aza to reactivate antigen expression in tumors in situ generated highly significant improvements in therapy over treatment with vaccine or 5-Aza alone. These data show that inflammatory killing of normal cells activates a potent T cell response targeted against a specific subset of self-antigens but can also lead to the immunoselection of tumor variants. Moreover, our data indicate that emergence of antigen loss variants may often be due to reversible epigenetic mechanisms within the tumor cells. Therefore, combination therapy using vaccination and systemic treatment with 5-Aza or other demethylating agents may have significant therapeutic benefits for antitumor immunotherapy.

Cells with endothelial phenotype generated from adult peripheral blood have emerging diagnostic and therapeutic potential. This study examined the lineage relationship between, and angiogenic function of, early endothelial progenitor cells (EPCs) and late outgrowth endothelial cells (OECs) in culture. Culture conditions were established to support the generation of both EPCs and OECs from the same starting population of peripheral blood mononuclear cells (PBMCs). Utilizing differences in expression of the surface endotoxin receptor CD14, it was determined that the vast majority of EPCs arose from a CD14 + subpopulation of PBMCs but OECs developed exclusively from the CD14 − fraction. Human OECs, but not EPCs, expressed key regulatory proteins endothelial nitric oxide synthase (eNOS) and caveolin-1. Moreover, OECs exhibited a markedly greater capacity for capillary morphogenesis in in vitro and in vivo matrigel models, tube formation by OECs being in part dependent on eNOS function. Collectively, these data indicate lineage and functional heterogeneity in the population of circulating cells capable of assuming an endothelial phenotype and provide rationale for the investigation of new cell-therapeutic approaches to ischemic cardiovascular disease.

Background— Bone marrow–derived cells have been shown to contribute to endothelial replacement after vascular injury. In vitro culture of peripheral blood mononuclear cells produces cells with phenotypic characteristics of endothelium. To test the hypothesis that delivery of autologous culture-modified mononuclear cells (CMMCs) to injured arteries could attenuate the vascular response to injury, a rabbit model was studied. Methods and Results— Rabbit peripheral blood mononuclear cells were cultured in endothelial growth media for 7 to 12 days, yielding highly proliferative cells with distinct endothelial phenotype (expressing CD31 and endothelial nitric oxide synthase and capable of acetylated LDL uptake). A rabbit model of balloon carotid injury was used to evaluate the effect of day 7 CMMC delivery on vascular responses. Animals underwent balloon injury and immediate delivery of autologous CMMCs or buffered saline by 20 minutes of local dwelling. Fluorescence-labeled CMMCs were detected in all vessel layers 4 weeks after delivery. Colonies of cells that localized to the lumen and stained for endothelial markers were also identified. Local CMMC administration at the time of balloon injury accelerated reendothelialization at 4 weeks compared with saline ( P <0.05). Moreover, CMMC delivery markedly improved endothelium-dependent vasoreactivity at 4 weeks compared with saline ( P <0.005). Finally, CMMC treatment reduced neointimal formation by 55% at 4 weeks ( P <0.05). Conclusions— These data demonstrate that delivery of CMMCs to balloon-injured arteries is associated with accelerated reendothelialization, enhanced endothelium-dependent vasoreactivity, and reduced neointimal formation. Thus, delivery of autologous CMMCs represents a novel vasculoprotective approach to attenuate the response to acute vascular injury.

Derivatives of the Edmonston-B strain of measles virus (MV-Ed) are safe, live attenuated measles virus (MV) vaccines that have been used worldwide for more than 30 years. The cytoreductive potential of MV-Ed has been investigated in murine models of both aggressive and indolent B-cell lymphoma in severe combined immunodeficient (SCID) mice. The rationale for these studies was generated by experience with viral fusogenic membrane glycoproteins as cytotoxic genes and the recognition of the potential of replicating viruses in the treatment of human malignancy. Intratumoral injection of both unmodified MV-Ed and a strain of MV-Ed genetically modified by the addition of a β-galactosidase reporter gene (MVlacZ) induced regression of large established human lymphoma xenografts, in contrast to control therapy with UV-inactivated virus, in which all tumors progressed. The antitumor effect still occurred in the presence of passively transferred anti-MV antibody. Intravenous administration of MV also resulted in considerable slowing of tumor progression. Analysis of sections of residual tumor confirmed replication of MV within the tumors. Thus, the vaccine strain of MV mediates regression of large, established human B-cell lymphoma xenografts in SCID mice, and proof of principle is established that MV is oncolytic for lymphomas in vivo. Attenuated MVs may have value as a novel replicating-virus therapy for this group of disorders.