Erskine, Courtney L.

Abstract Background: Epithelial ovarian cancer (EOC) is the fifth leading cause of cancer-related death in females and leading gynecologic cause of cancer-related death. Despite the identification of a number of serum biomarkers, methods to identify early-stage disease and predict prognosis remain scarce. We have evaluated two biologically connected serum biomarkers, serum leukocyte protease inhibitor (SLPI) and progranulin (PGRN). Methods: Two-hundred frozen plasma samples were acquired from the Mayo Clinic Biospecimen Repository for Ovarian Cancer Research. Samples were obtained from 50 patients with benign conditions, 50 with American Joint Committee on Cancer (AJCC) stage I and II EOC, and 100 with AJCC stage III and IV EOC. Samples were obtained before surgical resection of a mass and were analyzed for absolute levels of SLPI and PGRN using ELISA assays. Receiver-operator characteristic curves were generated for SLPI and PGRN. Median follow-up was 48 months. Results: Absolute levels of SLPI were significantly elevated in patients with EOC compared with benign disease and predicted the presence of EOC (AUC of 0.812; P = 0.04); SLPI remained elevated in the subset of patients with normal CA-125. PGRN levels were not significantly increased in patients with early-stage or late-stage EOC as a whole, but an increase in PGRN levels was associated with decreased overall survival in advanced EOC. Conclusions: SLPI levels are elevated in EOC, and SLPI shows promise as a diagnostic biomarker for patients with both elevated and normal CA-125 levels. An increase in PGRN is associated with decreased overall survival. Impact: SLPI is elevated in EOC and warrants investigation in a screening study in women at risk for EOC. Cancer Epidemiol Biomarkers Prev; 22(10); 1730–5. ©2013 AACR.

Abstract Patients with HER-2/neu–expressing breast cancer remain at risk for relapse following standard therapy. Vaccines targeting HER-2/neu to prevent relapse are in various phases of clinical testing. Many vaccines incorporate the HER-2/neu HLA-A2–binding peptide p369–377 (KIFGSLAFL), because it has been shown that CTLs specific for this epitope can directly kill HER-2/neu–overexpressing breast cancer cells. Thus, understanding how tumors process this epitope may be important for identifying those patients who would benefit from immunization. Proteasome preparations were used to determine if p369–377 was processed from larger HER-2/neu–derived fragments. HPLC, mass spectrometry, cytotoxicity assays, IFN-γ ELISPOT, and human breast cancer cell lines were used to assess the proteolytic fragments. Processing of p369–377 was not detected by purified 20S proteasome and immunoproteasome, indicating that tumor cells may not be capable of processing this Ag from the HER-2/neu protein and presenting it in the context of HLA class I. Instead, we show that other extracellular domain HER-2/neu peptide sequences are consistently processed by the proteasomes. One of these sequences, p373–382 (SLAFLPESFD), bound HLA-A2 stronger than did p369–377. CTLs specific for p373–382 recognized both p373–382 and p369–377 complexed with HLA-A2. CTLs specific for p373–382 also killed human breast cancer cell lines at higher levels than did CTLs specific for p369–377. Conversely, CTLs specific for p369–377 recognized p373–382. Peptide p373–382 is a candidate epitope for breast cancer vaccines, as it is processed by proteasomes and binds HLA-A2.

Abstract Background: Ovarian cancer (OC) is the leading cause of gynecologic cancer death in the United States. Survival in advanced OC is highly variable; some patients are cured of their disease with a combination of surgery and systemic chemotherapy, while the majority of patients develop recurrence and ultimately die of metastatic OC. While markers of poor prognosis within advanced OC exist, they have not translated to changes in therapy or outcomes. Vascular growth factors are important soluble mediators of tumor growth, vasculogenesis and angiogenesis that may be targeted therapeutically. We therefore explored the association between plasma levels of vascular growth factors and clinical outcomes in advanced OC. Methods: We enrolled 200 patients with OC or benign surgical conditions from the Mayo Ovarian SPORE Biospecimens Core. Presurgical plasma samples from patients with advanced OC (AJCC Stage III and IV, n = 100), early stage OC (Stage I and II, n = 50), and benign surgical conditions (n = 50) were assayed for vascular growth factors via multiplex electrochemiluminescence and by ELISA. Differences in plasma levels between benign, early, and advanced OC patient groups were assessed using plate-adjusted linear models. Associations between plasma levels of vascular growth factors and overall survival in advanced OC patients were assessed by Cox proportional hazards models. Results: Both vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) levels were increased in patients with advanced OC (mean ng/mL = 130.8, p = 0.004; mean ng/mL = 20.1, p = 0.025, respectively) compared to patients with early stage (mean ng/mL = 75.1 and 19.0 respectively) and benign conditions (mean ng/mL = 86.8 and 15.0, respectively). An increase in PlGF levels was associated with poor overall survival in patients with advanced OC (HR = 2.52, p = 0.005), while increase in VEGF levels were of borderline significance (HR = 1.21, p = 0.061) Conclusions: Soluble PlGF and VEGF are increased in the setting of advanced OC. Increased plasma PlGF is strongly linked to poor prognosis, while VEGF levels have a borderline association with prognosis. These data provide a rationale for therapeutic targeting of both VEGF and PlGF. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1382. doi:1538-7445.AM2012-1382

Abstract CD4 Th cells are critical to the development of coordinated immune responses to infections and tumors. Th cells are activated through interactions of the TCR with MHC class II complexed with peptide. T cell activation is dependent on the density of MHC peptide complexes as well as the duration of interaction of the TCR with APCs. In this study, we sought to determine whether MHC class II peptides could be modified with amino acid sequences that facilitated uptake and presentation with the goal of improving Th cell activation in vitro and in vivo. A model epitope derived from the murine folate receptor α, a self- and tumor Ag, was modified at its carboxyl terminus with the invariant chain-derived Ii-Key peptide and at its N terminus with a peptide that enhances uptake of Ag by APC. Modification of a peptide resulted in enhanced generation of high-avidity murine folate receptor α T cells that persisted in vivo and homed to sites of Ag deposition. The nesting approach was epitope and species independent and specifically excluded expansion of CD4 regulatory T cells. The resulting Th cells were therapeutic, enhanced in vivo helper activity and had an increased ability to resist tolerizing immune microenvironments. In addition to improved immunoadjuvants, this epitope modification strategy may be useful for enhancing ex vivo and in vivo generation of Th cells for preventing and treating diseases.

Abstract Within the ovarian cancer microenvironment, there are several mechanisms that suppress the actions of antitumor immune effectors. Delineating the complex immune microenvironment is an important goal toward developing effective immune-based therapies. A dominant pathway of immune suppression in ovarian cancer involves tumor-associated and dendritic cell (DC)-associated B7-H1. The interaction of B7-H1 with PD-1 on tumor-infiltrating T cells is a widely cited theory of immune suppression involving B7-H1 in ovarian cancer. Recent studies suggest that the B7-H1 ligand, programmed death receptor-1 (PD-1), is also expressed on myeloid cells, complicating interpretations of how B7-H1 regulates DC function in the tumor. In this study, we found that ovarian cancer-infiltrating DCs progressively expressed increased levels of PD-1 over time in addition to B7-H1. These dual-positive PD-1+ B7-H1+ DCs have a classical DC phenotype (i.e., CD11c+CD11b+CD8−), but are immature, suppressive, and respond poorly to danger signals. Accumulation of PD-1+B7-H1+ DCs in the tumor was associated with suppression of T cell activity and decreased infiltrating T cells in advancing tumors. T cell suppressor function of these DCs appeared to be mediated by T cell-associated PD-1. In contrast, ligation of PD-1 expressed on the tumor-associated DCs suppressed NF-κB activation, release of immune regulatory cytokines, and upregulation of costimulatory molecules. PD-1 blockade in mice bearing ovarian cancer substantially reduced tumor burden and increased effector Ag-specific T cell responses. Our results reveal a novel role of tumor infiltrating PD-1+B7-H1+ DCs in mediating immune suppression in ovarian cancer.

AbstractPurpose: Over the past two decades, there has been significant interest in targeting HER-2/neu in immune-based approaches for the treatment of HER-2/neu+ cancers. For example, peptide vaccination using a CD8 T cell–activating HER-2/neu epitope (amino acids 369-377) is an approach that is being considered in advanced phase clinical trials. Studies have suggested that the persistence of HER-2/neu–specific CD8 T cells could be improved by incorporating human leukocyte antigen (HLA) class II epitopes in the vaccine. Our goal in this study was to identify broad coverage HLA-DR epitopes of HER-2/neu, an antigen that is highly expressed in a variety of carcinomas.Experimental Design: A combination of algorithms and HLA-DR–binding assays was used to identify HLA-DR epitopes of HER-2/neu antigen. Evidence of preexistent immunity in cancer patients against the identified epitopes was determined using IFN-γ enzyme-linked immunosorbent spot (ELIspot) assay.Results: Eighty-four HLA-DR epitopes of HER-2/neu were predicted, 15 of which had high binding affinity for ≥11 common HLA-DR molecules. A degenerate pool of four HLA-DR–restricted 15-amino acid epitopes (p59, p88, p422, and p885) was identified, against which >58% of breast and ovarian cancer patients had preexistent T-cell immunity. All four epitopes are naturally processed by antigen-presenting cells. Hardy-Weinberg analysis showed that the pool is useful in ∼84% of population. Lastly, in this degenerate pool, we identified a novel in vivo immunodominant HLA-DR epitope, HER-2/neu88-102 (p88).Conclusion: The broad coverage and natural immunity to this epitope pool suggests potential usefulness in HER-2/neu–targeting, immune-based therapies such as vaccines. Clin Cancer Res; 16(3); 825–34

AbstractRecent studies have shown the importance of helper CD4 T cells in initiating and sustaining tumor-specific CD8 T-cell immunity. This has paved the way for identifying MHC class II epitopes that could be incorporated into class I–based vaccines. In this study, the goal was to identify an HLA-DR–degenerate epitope pool derived from insulin-like growth factor binding protein 2 (IGFBP-2). IGFBP-2, a regulator of insulin-like growth factor action, is overexpressed in the majority of breast and ovarian cancers. Using algorithms, we predicted 29 HLA-DR1–binding epitopes. Binding assays targeting 15 different HLA-DRs revealed that 10 epitopes were degenerate, binding to at least four different HLA-DR variants. An IFN-γ enzyme-linked immunosorbent spot assay was used to assess immunity to these 10 epitopes in 48 patients with either breast or ovarian cancer and 18 controls. Elevated T-cell immunity in patients was detected in 4 of the 10 epitopes (IGFBP2.17, IGFBP2.22, IGFBP2.249, and IGFBP2.293). The cumulative T-cell frequency of these four epitopes was elevated in patients relative to controls. All four peptides are naturally processed and presented to CD4 T-cells. The degenerate pool of peptides covers nearly 80% of patients and may be useful for augmenting CD4 T-cell immunity in patients undergoing immunization. [Cancer Res 2008;68(12):4893–901]

Abstract Studies have shown that the immune system can recognize self-antigens under conditions (eg, cell injury) in which the self-tissue might elaborate immune-activating endogenous danger signals. Uric acid (UA) is an endogenous danger signal recently identified to be released from dying cells. Prior work has shown that UA activates immune effectors of both the innate and adaptive immune system, including neutrophils and cytotoxic T-cell immunity. However, it was unclear whether UA could enhance antibody immunity, which was examined in this study. When added to dying tumor cells or with whole protein antigen, UA increased IgG1-based humoral immunity. Further, UA blocked growth of tumor in subsequent tumor challenge experiments, which depended on CD4, but not CD8, T cells. Sera derived from UA-treated animals enhanced tumor growth, suggesting it had little role in the antitumor response. UA did not signal for T-cell expansion or altered tumor-infiltrating leukocyte populations. Consistent with the lack of T-cell expansion, when applied to dendritic cells, UA suppressed T-cell growth factors but up-regulated B cell–activating cytokines. Understanding the nature of endogenous danger signals released from dying cells may aid in a better understanding of mechanisms of immune recognition of self.

PurposeStudies have demonstrated that the generation of immunity to tumor antigens is associated with improved prognosis for many cancers. A candidate antigen is the folate receptor alpha (FRα), which is overexpressed in breast and ovarian cancers. Our goal in this study was to attain a better understanding of the extent of endogenous FRα immunity.MethodsUsing a CD4+T cell epitope prediction algorithm, we predicted promiscuous epitopes of FRα, and tested for immunity in 30 breast (n = 17) or ovarian (n = 13) cancer patients and 18 healthy donors using enzyme-linked immunospot analysis.ResultsFourteen peptides were predicted, seven each from the carboxy- and amino-terminus halves of the protein. More than 70% of patients demonstrated immunity to at least one FRα peptide. Patients responded to an average of 3 ± 0.5 peptides, whereas healthy donors responded to 1 ± 0.4 peptides (P = .004). Five peptides were recognized by more than 25% of patients. Responses to three peptides were higher (P < .05) in patients than in healthy donors, suggesting augmented immunity. Compared with healthy individuals, patients developed higher immunity to the amino-terminus half of the receptor (P = .03). There was no difference between each group in the responses to nonspecific (P = .2) and viral stimuli (P = .5). Lastly, patients demonstrated elevated levels of FRα antibodies consistent with a coordinated immune response.ConclusionThese findings demonstrate that the FRα is a target of the immune system in breast and ovarian cancer patients. Understanding which antigens are targeted by the immune system may be important for prognosis or immune-based therapies.