Immunologic principles and immunotherapeutic approaches in ovarian cancer

Chemokine receptors in epithelial ovarian cancer

Ovarian carcinoma is the deadliest gynecologic malignancy with very poor rate of survival, and it is characterized by the presence of vast incurable peritoneal metastasis. Studies of the role of chemokine receptors, a family of proteins belonging to the group of G protein-coupled receptors, in ovarian carcinoma strongly placed this family of membrane receptors as major regulators of progression of this malignancy. In this review, we will discuss the roles that chemokine-receptor interactions play to support angiogenesis, cell proliferation, migration, adhesion, invasion, metastasis, and immune evasion in progression of ovarian carcinoma. Data regarding the role that the chemokine receptors play in the disease progression accumulated insofar strongly suggest that this family of proteins could be good therapeutic targets against ovarian carcinoma.

Immunity of human epithelial ovarian carcinoma: the paradigm of immune suppression in cancer

Epithelial ovarian cancer (EOC) is a significant cause of cancer-related mortality in women, and there has been no substantial decrease in the death rates due to EOC in the last three decades. Thus, basic knowledge regarding ovarian tumor cell biology is urgently needed to allow the development of innovative treatments for EOC. Traditionally, EOC has not been considered an immunogenic tumor, but there is evidence of an immune response to EOC in patients. Clinical data demonstrate that an antitumor immune response and immune evasion mechanisms are correlated with a better and lower survival, respectively, providing evidence for the immunoediting hypothesis in EOC. This review focuses on the immune response and immune suppression in EOC. The immunological roles of chemotherapy and surgery in EOC are also described. Finally, we detail pilot data supporting the efficiency of immunotherapy in the treatment of EOC and the emerging concept that immunomodulation aimed at counteracting the immunosuppressive microenvironment must be associated with immunotherapy strategies.

Genetic and pharmacologic inhibition of complement impairs endothelial cell function and ablates ovarian cancer neovascularization

Complement activation plays a critical role in controlling inflammatory responses. To assess the role of complement during ovarian cancer progression, we crossed two strains of mice with genetic complement deficiencies with transgenic mice that develop epithelial ovarian cancer (TgMISIIR-TAg). TgMISIIR-TAg mice fully or partially deficient for complement factor 3 (C3) (Tg(+)C3(KO) and Tg(+)C3(HET), respectively) or fully deficient for complement factor C5a receptor (C5aR) (Tg(+)C5aR(KO)) develop either no ovarian tumors or tumors that were small and poorly vascularized compared to wild-type littermates (Tg(+)C3(WT), Tg(+)C5aR(WT)). The percentage of tumor infiltrating immune cells in Tg(+)C3(HET) tumors compared to Tg(+)C3(WT) controls was either similar (macrophages, B cells, myeloid-derived suppressor cells), elevated (effector T cells), or decreased (regulatory T cells). Regardless of these ratios, cytokine production by immune cells taken from Tg(+)C3(HET) tumors was reduced on stimulation compared to Tg(+)C3(WT) controls. Interestingly, CD31(+) endothelial cell (EC) function in angiogenesis was significantly impaired in both C3(KO) and C5aR(KO) mice. Further, using the C5aR antagonist PMX53, tube formation of ECs was shown to be C5a-dependent, possibly through interactions with the VEGF(165) but not VEGF(121) isoform. Finally, the mouse VEGF(164) transcript was underexpressed in C3(KO) livers compare to C3(WT) livers. Thus, we conclude that complement inhibition blocks tumor outgrowth by altering EC function and VEGF(165) expression.

In vitro-activated tumor-bearing host T cells and the effectiveness of tumor vaccine immunotherapy

BACKGROUND AND OBJECTIVE

Vaccination during periods of lymphopenia may facilitate immune responses to weak self-antigens and enhance antitumor immunity. The objective of this study was to determine the effectiveness of tumor vaccine immunotherapy combined with immune reconstruction using tumor-bearing host immune cells in lymphopenia, and to investigate the role of tumor-bearing host T cells activated in vitro during immunotherapy.

DESIGN AND SETTING

Animal study conducted in the First Affiliated Hospital of Xi'an Jiaotong University from January 2009 to January 2010.

PATIENTS AND METHODS

Lymphopenia was induced by cyclophosphamide. A reconstituted immune system with different syngeneic lymphocytes was employed, including lymphocytes from naïve rats (unsensitized group), tumor-bearing rats (tumor-bearing group), and tumor-bearing rats activated in vitro (activated group). All rats were immunized with granulocyte-macrophage colony-stimulating factor (GM-CSF)-modified NuTu-19 ovarian cancer (GM-CSF/NuTu-19) cells. Tumor vaccine-draining lymph nodes (TVDLNs) were harvested, and then stimulated to induce effector T cells (T(E)). T(E) were then adoptively transferred to rats bearing a 3-day pre-established abdominal tumor (NuTu-19), and the survival rate was calculated.

RESULTS

Compared with the unsensitized group, the levels of interleukin-2 (IL-2) were significantly lower in the tumor-bearing group, whereas that of IL-4 were significantly higher (P<.05). The number of CD4+ T cells secreting interferon-γ and the specific cytotoxicity of CD8+ cytotoxic T lymphocytes were significantly lower (P<.05). The survival was significantly higher in the activated group compared with the other groups.

CONCLUSIONS

Lymphocytes from tumor-bearing rats activated in vitro can effectively reverse the immunosuppressive effects of tumor-bearing hosts.

Immunorecognition of the 14F7 Mab Raised against N-Glycolyl GM3 Ganglioside in Some Normal and Malignant Tissues from Genitourinary System

N-glycolyl neuraminic acid has been considered as a tumour-associated antigen forming both glycolipid and glycoprotein, expressed in some human malignant cells. In this work, we evaluate the 14F7 Mab (an IgG1 murine highly specific to N-glycolyl GM3 ganglioside) reactivity in a variety of genitourinary-system-derived tumors as well as in their normal counterparts. Immunohistochemical assays with 14F7 followed by anti-mouse biotinylated antibody and ABC/HRP system using formalin-fixed and paraffin-embedded tissues were carried out. In normal tissues, 14F7 was reactive only in renal tubules of kidney (2/6) and in the stromal component and blood vessels of ovary (3/5). Tumors of kidney (12/38), urinary bladder (8/9), breast (41/42), ovary (21/34), testis (4/5), prostate (17/20), and uterus (5/14) as well as prostatic nodular hyperplasia (5/8) were stained with 14F7. N-glycolyl GM3 recognized by 14F7 could be considered as one attractive target for both active and passive immunotherapy of genitourinary malignancies expressing this molecule.

Expression of tumor-specific antigen MAGE, GAGE and BAGE in ovarian cancer tissues and cell lines

Background

To observe mRNA expression of tumor-specific antigen MAGE, BAGE and GAGE in epithelial ovarian cancer tissues and cell lines, to explore the relationship between gene expression and diagnosis, treatment and prognosis of ovarian cancer, and to evaluate the feasibility of their gene products as markers, and an immunotherapy target for ovarian cancer.

Methods

mRNA expression of MAGE-1, MAGE-3, GAGE-1/2 and BAGE were determined by reverse transcription polymerase chain reaction (RT-PCR) in 14 cases of normal ovarian tissue, 20 cases of ovarian benign tumor specimens, 41 cases of ovarian cancer specimens, and ovarian cancer cell lines SKOV3, A2780, and COC1.

Results

MAGE, GAGE and BAGE genes were not expressed in normal ovarian tissue. In benign tumors, only the MAGE gene was expressed; the expression rate of this gene in benign tumors was 15% (3/20). In ovarian cancer tissues, MAGE-1 and MAGE-3 was highly expressed, with expression rates of 53.7% (22/41) and 36.6% (15/41), while GAGE-1/2 and BAGE had relatively low expression, with rates of 26.8% (11/41) and 14.6% (6/41). In metastatic lesions of ovarian cancer, only MAGE-1 and BAGE were expressed, with expression rates of 28.6% (2/7) and 14.3% (1/7). The positive expression rates of MAGE-1 and MAGE-3 in serous cystadenocarcinoma were significantly higher than that in other types of ovarian cancer (P < 0.05). Gene expression rate was not correlated with menopause or lymph node metastasis. Positive expression of MAGE-1 and MAGE-3 was positively correlated with tumor differentiation and the clinical stage of the ovarian cancer. In addition, the positive expression rate of BAGE was significantly higher in ovarian cancer patients with ascites (P < 0.05). The mRNA expression profiles of MAGE, GAGE and BAGE in ovarian carcinoma cell lines SKOV3, A2780 and COC1 varied, but there was at least one gene expressed in each cell line.

Conclusion

Tumor-specific antigen MAGE, BAGE and GAGE may play a role in the occurrence and development of ovarian cancer. These genes can be used as one of the important indicators for early diagnosis, efficacy evaluation and prognostic determination of ovarian cancer.

Circadian rhythms and metabolic syndrome: from experimental genetics to human disease

The incidence of the metabolic syndrome represents a spectrum of disorders that continue to increase across the industrialized world. Both genetic and environmental factors contribute to metabolic syndrome and recent evidence has emerged to suggest that alterations in circadian systems and sleep participate in the pathogenesis of the disease. In this review, we highlight studies at the intersection of clinical medicine and experimental genetics that pinpoint how perturbations of the internal clock system, and sleep, constitute risk factors for disorders including obesity, diabetes mellitus, cardiovascular disease, thrombosis and even inflammation. An exciting aspect of the field has been the integration of behavioral and physiological approaches, and the emerging insight into both neural and peripheral tissues in disease pathogenesis. Consideration of the cell and molecular links between disorders of circadian rhythms and sleep with metabolic syndrome has begun to open new opportunities for mechanism-based therapeutics.

Immunologic markers of cancer progression and prognosis

During the past decade, significant progress has been made in understanding the interactions between the immune system and cancer. The re-emergence of cancer immunosurveillance and immunoediting concepts has provided an understanding of several immunologic markers that are associated with cancer progression and prognosis. Recent studies have attempted to define the critical role of tumor infiltration by lymphocytes as a reflection of a tumor-related immune response. More recently, there has been an improved ability to demonstrate distinct subsets of tumor-infiltrating lymphocytes (TILs) in different tumor compartments. Several of these studies indicate that the presence of TILs may be associated with improved clinical outcome in several human cancers. However, this improved clinical outcome is dependent upon the intratumoral balance and quality of TILs, or infiltration of regulatory T cells or myeloid-derived suppressor cells. Immunologic markers have an important role in demonstrating intermediate end points of a therapeutic intervention and ultimately may be useful in predicting clinical outcomes. These markers are important to the development of successful immunotherapy strategies in cancer.

Tregs and rethinking cancer immunotherapy

Tumors express antigens that should induce immune-mediated rejection, but spontaneous rejection of established tumors is rare. Recent work demonstrates that one reason for the lack of tumor rejection is that tumors actively defeat host immunity. This concept forces us to rethink current approaches to harnessing potent, specific host immunity to battle cancer, most of which are based on the paradigm that inducing more antitumor immune cells alone is therapeutic. However, as I discuss in this Personal Perspective, a newer paradigm predicts that reducing tumor-driven immune suppression will be clinically beneficial. CD4+CD25+ Tregs are one mechanism of tumor-driven immune evasion that provide prototypical targets for testing novel anticancer treatment strategies within the newer paradigm.

A pilot phase 2 study of oregovomab murine monoclonal antibody to CA125 as an immunotherapeutic agent for recurrent ovarian cancer

This prospective, open-label, pilot phase 2 study examined the clinical and immunologic effects of oregovomab (OvaRex) in heavily pretreated patients with recurrent ovarian cancer (OC). Thirteen women were administered intravenous oregovomab (2 mg) at weeks 0, 2, 4, 8, and 12, followed by quarterly doses for up to 2 years or disease progression. Concomitant chemotherapy was not permitted. Eligibility criteria included recurrence after one or more platinum-based chemotherapy regimens, CA125 >35 U/mL, evaluable or measurable disease. Tumor burden was evaluated by physical or radiologic methods pretreatment, weeks 12, 24, and every 24 weeks thereafter. Immune responses, including antibodies and T cells to oregovomab and CA125, were demonstrated in over half the patients. Stabilization of disease and survival >2 years was observed in 3 of 13 patients and coincided with robust immune responses. Shrinkage of marker lesions was not observed; however, four patients showed decreases in CA125 levels. Treatment was well tolerated without serious adverse events or discontinuations due to therapy. This pilot study supports immunologic activity and safety of oregovomab in recurrent OC. Further study of this agent in the consolidation and adjuvant setting is ongoing to establish its clinical utility.

HSP-10 in ovarian cancer: expression and suppression of T-cell signaling

OBJECTIVE

Suppressed T-cell activation is a hallmark of advanced ovarian cancer. Studies in pregnancy have demonstrated similar T-cell dysfunction mediated, at least in part, by HSP10, identified as "early pregnancy factor." This pilot study addresses the presence of HSP10 in the circulation of ovarian cancer patients and assesses its role in suppressing CD3-zeta.

METHODS

Sera were obtained from ovarian cancer patients (n = 10) and age-matched noncancer-bearing female controls (n = 9). HSP10 presence was determined semiquantitatively by Western immunoblotting in sera, ascites, and ovarian tumor cell conditioned media. The consequences of HSP10 on CD3-zeta suppression were defined using a Jurkat cell bioassay, using unfractionated patient sera, sera with HSP10 removed by immunoprecipitation and the immunoprecipitate.

RESULTS

HSP10 was detected in both sera and ascites of patients with ovarian cancer; however, it was not detectable in controls. HSP10 was also detected in the culture media of ovarian tumor cells. Sera containing HSP10 suppressed T-cell CD3-zeta expression, which correlated with HSP10 levels (r2 = 0.839). When HSP10 was removed from the sera, the ability to suppress CD3-zeta was diminished and the immunoprecipitated material was capable of suppressing CD3-zeta.

CONCLUSIONS

HSP10 appears to be produced and released from ovarian tumor cells and is detectable in the peripheral blood and ascites of patients. This circulating HSP10 appears to suppress T-cell expression of CD3-zeta, a key component of T-cell activation. Our findings indicate that, as in pregnancy, production and release of HSP10 may be a critical factor in the suppression of T-cell activation, allowing the tumor to escape immune surveillance.

Regulatory T Cells in Ovarian Cancer: Biology and Therapeutic Potential

Tumors express tumor-associated antigens (TAA) and thus should be the object of immune attack. Nonetheless, spontaneous clearance of established tumors is rare. Much work has demonstrated that tumors have numerous strategies either to prevent presentation of TAA, or to prevent TAA presentation in the context of T-cell co-signaling molecules. Thus, it was thought that lack of TAA-specific immunity was largely a passive process: tumors simply did not present enough TAA, or antigen-presenting cells did not have sufficient stimulatory capacity. On this basis, attempts were made to bolster TAA-specific immunity by using optimal antigen-presenting cells or by growing TAA-specific effector T cells ex vivo followed by adoptive transfer. These approaches met with some success in mouse models of human tumors, and showed some early clinical efficacy in human trials, although long-term efficacy remains to be established, and logistical problems are considerable. These studies established the concept that experimentally induced TAA-specific immunity is a rational and potentially efficacious means to treat cancer, including ovarian cancer. Nonetheless, recent work demonstrates that lack of naturally induced TAA-specific immunity is not simply a passive process. We discuss recent data clearly demonstrating that 'tumors actively prevent induction of TAA-specific immunity through induction of TAA-specific tolerance'. This tolerance is mediated in part by regulatory T cells (Tregs). Means to revert these tolerizing conditions represent a novel anticancer therapeutic stratagem. We discuss Tregs in this regard in human ovarian cancer and present evidence that depleting Treg in human cancer, including ovarian cancer, using denileukin diftitox (Ontak), improves immunity and may be therapeutic.