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Background: Saccharomyces cerevisiae (yeast) has been genetically modified to express CEA protein and employed as a heat-killed immune-stimulating, vector-based vaccine. Preclinical ...studies have shown that yeast CEA vaccine can induce a strong CEA-specific T-cell immune response (IR) and anti-tumor activity.
Methods: Patients (Pts) were enrolled in this phase I trial at 3 dose levels: 4, 16, and 40 yeast units (each unit =10
7
yeast particles). The vaccine was administered equally at 4 sites subcutaneously in bilateral inguinal and anterior chest wall regions. Vaccine was administered at 2 week intervals for 3 months, then monthly. Eligible pts were required to have a serum CEA > 5 ng/ml or > 20% CEA+ positive tumor block and no autoimmune history. An expansion cohort of 10 pts was enrolled to focus on IR. Pts had re-staging scans at 3 months, then bimonthly. Peripheral blood was collected for analysis of IR including the Effector/Regulatory T-cell ratio, ELISPOT assay, changes in the myeloid-derived suppressor cells (MDSC) and natural killer cells (NK).
Results: 25 pts with progressive metastatic CEA-expressing carcinoma were enrolled; 22 had colorectal adenocarcinoma. Vaccine was well tolerated with no dose limiting toxicities. The most common adverse event was grade 1/2 injection site reaction. Overall, 7 patients had stabilization or declines in serum CEA after treatment. Of them, 5 pts (3 with colorectal cancer) had stable disease beyond 3 months and 1 is still on-going (14 +, 8, 8, 4.5 and 4 months). No anti-CEA antibodies were detected. Post vs. pre-vaccination: a) five out of 9 evaluable pts showed evidence by ELISPOT of CEA-specific T-cell IRs b) 8/16 pts had increased and 8/16 pts had decreased CD4 Effector/Treg ratio and c) 6/13 pts had increased and 2/13pts had decreased NK frequency.
Conclusions: Saccharomyces cerevisiae-CEA demonstrated an acceptable safety profile. Although this is an advanced disease population of pts which is not ideal for immune-based therapy, CEA serum stabilizations and CEA-specific IRs were seen in some pts. Randomized studies are required to determine the clinical benefit of this vaccine in a more appropriate patient population for vaccine therapy.
In chronic lymphocytic leukemia (CLL), malignant B cells and nonmalignant T cells exhibit dysfunction. We previously demonstrated that infection of CLL cells with modified vaccinia Ankara (MVA) ...expressing the costimulatory molecules B7-1, ICAM-1, and LFA-3 (designated TRICOM) increased expression of these costimulatory molecules on the surface of CLL cells and thus augmented their antigen-presenting capability. Here, we evaluate the effect of MVA-TRICOM-modified CLL cells on T cells. Following incubation with irradiated MVA-TRICOM-modified CLL cells, allogeneic and autologous CD4⁺ and CD8⁺ T cells expressed significantly higher levels of B7-1, ICAM-1, and LFA-3. We show that this increase was the result of physical acquisition from the antigen-presenting cells (APCs), and that purified T cells that acquired costimulatory molecules from MVA-TRICOM-modified CLL cells were able to stimulate the proliferation of untreated T cells. These results demonstrate for the first time that T cells from CLL patients can acquire multiple costimulatory molecules from autologous CLL cells and can then act as APCs themselves. Given the immunodeficiencies characteristic of CLL, enhancing the antigen-presenting function of CLL cells and T cells simultaneously could be a distinct advantage in the effort to elicit antitumor immune responses.
The purpose of this study was to determine the feasibility and maximum tolerated dose of (90)Yttrium-CC49 ((90)Y-CC49) as the radioimmunotherapy (RIT) component of an i.p. combined modality treatment ...for recurrent ovarian cancer.
A Phase I trial of (90)Y-CC49 RIT was conducted in ovarian cancer patients who had persistent or recurrent intra-abdominal disease, had failed one or two prior chemotherapy regimens, and demonstrated TAG-72 expression. Patients were treated with a previously established combined modality treatment protocol of s.c. IFN alpha2b, i.p. paclitaxel, and increasing dosages of i.p. (90)Y-CC49. Patients were monitored for toxicity, generation of human antimouse antibody response, and clinical efficacy.
Twenty eligible patients were treated per study specifications. All patients had been treated with debulking and paclitaxel/carboplatin-based chemotherapy at initial diagnosis. The patients included 11 patients with persistent disease at the time of second look laparotomy and 9 patients with delayed recurrence. Patients were treated with i.p. (90)Y-CC49 given in combination with s.c. IFN alpha2b (dose of 3 x 10(6) units for a total of four doses) and i.p. paclitaxel (dose of 100 mg/m(2)). RIT treatment was associated with primarily hematological toxicity. The maximum tolerated dose of i.p. (90)Y-CC49 was established at 24.2 mCi/m(2) in this combined regimen. Of nine patients with measurable disease, two had partial responses lasting 2 and 4 months. Of 11 patients with nonmeasurable disease, median time to progression was 6 months in 7 patients who recurred; 4 of these patients remain no evidence of disease at 9+, 18+, 19+, and 23+ months.
(90)Yttrium-CC49-based RIT in combination with IFN alpha2b and i.p. paclitaxel is feasible and well tolerated at a dose of < or =24.2 mCi/m(2).
The prevalence of obesity, an established risk factor for several chronic diseases, including cancer, has risen dramatically over the past 4 decades. Dietary change and/or increased physical activity ...are the most commonly recommended lifestyle-based strategies for preventing or reversing obesity. One of several physiological systems that may be enhanced by dietary change and exercise is the immune system. In this study, we examined the effects of energy restriction (ER; 30% reduction relative to control energy intake) and/or exercise (EX; voluntary wheel running) on systemic and mucosal immune function. Female C57BL/6 mice were randomized into 4 treatment conditions: 1) controls consumed ad libitum (AL); 2) AL with access to running wheels (AL + EX); 3) 30% ER; and 4) 30% ER with access to running wheels (ER + EX). Both ER and EX reduced spleen weight and the number of splenic T and B lymphocytes (P < 0.05). ER enhanced natural killer (NK) cell function, but reduced concanavalin A (Con A)-induced T-cell proliferation (P < 0.05). In contrast, EX enhanced Con A-induced proliferation and cytokine production from Peyer's patch cells (P < 0.05). These data suggest that ER and EX enhance some, but not all, components of the immune system and are likely working via different biological mechanisms to regulate NK and T-cell function.
We report here both the range and patterns of reactivity of an IgG1 monoclonal antibody, B72.3, prepared against human, metastatic mammary carcinoma cells. When the avidin-biotin complex (ABC) ...immunoperoxidase technique was used on tissue sections, monoclonal B72.3 reacted with 19 of 41 (46%) primary mammary carcinomas and 13 of 21 (62%) metastatic lesions, either in axillary lymph nodes or at distal sites. Variable concentrations of antigen, recognized by B72.3, were observed among mammary tumors, as well as among different cell populations of a given tumor mass. Several patterns of antigen distribution were observed: membrane, diffuse cytoplasmic, focal and marginal. No reactivity was observed to normal mammary epithelium, stroma, or lymphocytes of the breast, nor to any cell types in a variety of other normal human tissues, melanomas, and sarcomas. Reactivity with all of four colon carcinomas was also observed. Assay of serial sections of mammary carcinomas with B72.3 and a monoclonal antibody directed against carcinoembryonic antigen demonstrated that these antigens were both distinct and non-coordinately expressed.
It is believed that the efficacy of antigen-specific CD8
+
cytotoxic T lymphocytes (CTLs) depends not only on the quantity of CTL generated, but perhaps, more importantly, on the avidity of the CTL. ...To date, however, no strategy has been demonstrated to preferentially induce higher avidity human CTL. In the present study, antigen-presenting cells (APC) generated from human peripheral blood mononuclear cells (PBMC) were infected with a recombinant avipox vector (rF-) containing the transgenes for a TRIad of COstimulatory Molecules (human B7-1, ICAM-1 and LFA-3, designated as rF-TRICOM) and then used to elicit peptide-specific CTL from autologous T cells. Compared with peptide-pulsed non-infected APC, or peptide-pulsed APC infected with wild-type vector, peptide-pulsed APC infected with rF-TRICOM induced not only more CTL, but also higher avidity CTL; this was demonstrated by tetramer staining, tetramer dissociation, IFN-γ production and cytolytic assays. Peptide-pulsed rF-TRICOM–infected dendritic cells (DC) were also shown to induce CTL with a greater than 10-fold higher avidity than CTL induced using CD40L-matured dendritic cells (DC); the use of peptide-pulsed CD40L-matured DC infected with rF-TRICOM as APC induced CTL of even greater avidity. To our knowledge, these studies are the first to demonstrate a methodology to induce higher avidity human CTL and have implications for the development of more efficient vaccines for a range of human cancers.
Tumor-associated antigens (TAAs) are by definition either weakly immunogenic or functionally nonimmunogenic. Vaccine strategies have been designed to present TAAs to the immune system that may result ...in far greater activation of T cells than that occurring naturally in the host. These strategies include (1) placing the gene coding for the tumor antigen into poxvirus vectors as a transgene; (2) using diversified prime-and-boost vaccine strategies employing two different types of poxvirus vectors; (3) using T-cell costimulation; and (4) using cytokines, including GM-CSF, as biologic adjuvants. Preclinical studies have been performed comparing the effects on induction of antigen-specific CD8 and CD4 T-cell responses using recombinant poxvirus vectors containing transgenes for a TAA and costimulatory molecules B7-1, ICAM-1, and LFA-3 (designated TRICOM). Antigen-specific T-cell responses were greatest in the group receiving the CEA-TRICOM vaccines and were shown to correlate with survival. We have now completed the first clinical trials with poxvirus vectors containing TRICOM, using the TAAs PSA, CEA, and MUC-1. In addition, clinical studies combining vaccines with radiation therapy, chemotherapy, and second-line hormone therapy have provided preliminary evidence of prolongation of time to disease progression and antigen cascade postvaccination.
Systemic IL-2 is currently employed in the therapy of several tumor types, but at the price of often severe toxicities. Local vector mediated delivery of IL-2 at the tumor site may enhance local ...effector cell activity while reducing toxicity. To examine this, a model using CEA-transgenic mice bearing established CEA expressing tumors was employed. The vaccine regimen was a s.c. prime vaccination with recombinant vaccinia (rV) expressing transgenes for CEA and a triad of costimulatory molecules (TRICOM) followed by i.t. boosting with rF-CEA/TRICOM. The addition of intratumoral (i.t.) delivery of IL-2 via a recombinant fowlpox (rF) IL-2 vector greatly enhanced anti-tumor activity of a recombinant vaccine, resulting in complete tumor regression in 70-80% of mice. The anti-tumor activity was shown to be dependent on CD8(+) cells and NK1.1(+). Cellular immune assays revealed that the addition of rF-IL-2 to the vaccination therapy enhanced CEA-specific tetramer(+) cell numbers, cytokine release and CTL lysis of CEA(+) targets. Moreover, tumor-bearing mice vaccinated with the CEA/TRICOM displayed an antigen cascade, i.e., CD8(+) T cell responses to two other antigens expressed on the tumor and not the vaccine: wild-type p53 and endogenous retroviral antigen gp70. Mice receiving rF-IL-2 during vaccination demonstrated higher avidity CEA-specific, as well as higher avidity gp70-specific, CD8(+) T cells when compared with mice vaccinated without rF-IL-2. These studies demonstrate for the first time that the level and avidity of antigen specific CTL, as well as the therapeutic outcome can be improved with the use of i.t. rF-IL-2 with vaccine regimens.
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.
New gene expressed in prostate (NGEP) is a prostate-specific gene encoding either a small cytoplasmic protein (NGEP-S) or a larger polytopic membrane protein (NGEP-L). NGEP-L expression is detectable ...only in prostate cancer, benign prostatic hyperplasia and normal prostate. We have identified an HLA-A2 binding NGEP epitope (designated P703) which was used to generate T cell lines from several patients with localized and metastatic prostate cancer. These T cell lines were able to specifically lyse HLA-A2 and NGEP-expressing human tumor cells. NGEP-P703 tetramer binding assays demonstrated that metastatic prostate cancer patients had a higher frequency of NGEP-specific T cells when compared with healthy donors. Moreover, an increased frequency of NGEP-specific T cells was detected in the peripheral blood mononuclear cells of prostate cancer patients post-vaccination with a PSA-based vaccine, further indicating the immunogenicity of NGEP. These studies thus identify NGEP as a potential target for T cell-mediated immunotherapy of prostate cancer.
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