Elimination of IL-10-inducing T-helper epitopes from an IGFBP-2 vaccine ensures potent antitumor activity

Immunization against self-tumor antigens can induce T-regulatory cells, which inhibit proliferation of type I CD4(+) T-helper (TH1) and CD8(+) cytotoxic T cells. Type I T cells are required for potent antitumor immunity. We questioned whether immunosuppressive epitopes could be identified and deleted from a cancer vaccine targeting insulin-like growth factor-binding protein (IGFBP-2) and enhance vaccine efficacy. Screening breast cancer patient lymphocytes with IFN-γ and interleukin (IL)-10 ELISPOT, we found epitopes in the N-terminus of IGFBP-2 that elicited predominantly TH1 whereas the C-terminus stimulated TH2 and mixed TH1/TH2 responses. Epitope-specific TH2 demonstrated a higher functional avidity for antigen than epitopes, which induced IFN-γ (P = 0.014). We immunized TgMMTV-neu mice with DNA constructs encoding IGFBP-2 N-and C-termini. T cell lines expanded from the C-terminus vaccinated animals secreted significantly more type II cytokines than those vaccinated with the N-terminus and could not control tumor growth when infused into tumor-bearing animals. In contrast, N-terminus epitope-specific T cells secreted TH1 cytokines and significantly inhibited tumor growth, as compared with naïve T cells, when adoptively transferred (P = 0.005). To determine whether removal of TH2-inducing epitopes had any effect on the vaccinated antitumor response, we immunized mice with the N-terminus, C-terminus, and a mix of equivalent concentrations of both vaccines. The N-terminus vaccine significantly inhibited tumor growth (P < 0.001) as compared with the C-terminus vaccine, which had no antitumor effect. Mixing the C-terminus with the N-terminus vaccine abrogated the antitumor response of the N-terminus vaccine alone. The clinical efficacy of cancer vaccines targeting self-tumor antigens may be greatly improved by identification and removal of immunosuppressive epitopes.

Evaluation of cancer immunity in mice

There have been significant advances in the development and application of novel therapeutic approaches and improved diagnostics for cancer in the past decade. Manipulation and/or assessment of cancer-specific immunity have been central to these advances. Murine models are a standard for the preclinical development of cancer immunotherapeutics. However, critical advances in our understanding of the role of the immune microenvironment and the assessment of cancer-specific immunity have not been fully applied to rodent models. Methods to preserve the function of immune cells after cryopreservation and standard approaches to quantitative immune assays have not been developed. Furthermore, a detailed evaluation of the immune tumor environment, which can impact a clinical response to different agents, is rarely undertaken as models are being contemplated. Rapid translation of immunoncology agents to the clinic will require standardization of immunologic assay methods and a more detailed immunologic characterization of common mouse models. Outlined here are the critical elements in assessing immunity in cancer mouse models and suggestions concerning the standardization of approaches when using these models for the study of immunoncology.

Abstract P5-01-09: Early tumor antigens discovered in TgMMTV-neu mice may provide targets for early breast cancer diagnosis and prevention

Breast cancer is immunogenic and breast tumor proteins stimulate both an antibody and a T cell immune response. Identification of cancer related proteins that become immunogenic prior to the clinical development of cancer may allow the use of humoral immunity to identify those “exposed” to the cancer phenotype. Alternatively, these proteins that become aberrant enough to trigger such early immune recognition may be ideal targets for a vaccine aimed at preventing the development of breast cancer. We used the TgMMTV-neu mouse model to discover immunogenic proteins i.e. proteins expressed in pre-invasive breast cancer. The mammary tumors in these mice are genotypically similar to human luminal breast cancer and can be evaluated longitudinally, allowing for collection of pre-diagnostic sera prior to tumor development to use for antigen discovery.

We identified 6 antigens that were present in mice prior to the development of mammary cancer (Pdhx, Otud6b, Stk39, Zpf238, Lgals8, and Vps35). These proteins were associated with inflammation, autoimmunity, and cellular homeostasis. In mouse validation cohorts, detecting IgM and IgG antibody responses against a panel of three “pre-diagnostic” tumor antigens discriminated pre-diagnostic sera from non-transgenic control sera with an AUC of 0.924. We next evaluated samples obtained from the Women's Health Initiative Study and demonstrated women with autoantibodies to the human homologues of these proteins. IgM and IgG autoantibodies to the “pre-diagnostic” antigen panel could discriminate the samples of women who eventually developed breast cancer from matched controls. The discriminatory potential of the pre-diagnostic autoantibodies was enhanced if samples were collected more than 5 months prior to diagnosis (AUC 0.68; CI 0.565-0.787). We questioned whether these antigens, which could predict women who would eventually develop breast cancer, could mediate anti-tumor immunity. When TgMMTV-neu mice (n = 5/group) were vaccinated with the individual antigens, vaccination with Pdhx inhibited tumor growth by 62.1%, Otud6B inhibited tumor growth by 23.5%, and Stk39 inhibited tumor growth by 50.3% as compared to empty vector vaccinated control at 27 weeks (p&lt;0.001 for each of the individual antigens as compared to empty vector). Spontaneous tumorigenesis was inhibited in TgMMTV-neu mice (n = 20 mice/group) vaccinated with a panel of three of the “pre-diagnostic” antigens (Pdhx, Otud6b, and Stk39) inhibited tumor growth by 27.3% by 37 weeks as compared to vector vaccinated mice (p&lt;0.05). These data suggest that the same pre-invasive breast tumor proteins are found in mice and women and vaccines against these pre-invasive breast cancer proteins inhibit tumorigenesis in mice, future studies will address if these antigens elicit T-cell responses in patients with high risk breast lesions.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-01-09.

Protein-bound polysaccharide-K induces IL-1β via TLR2 and NLRP3 inflammasome activation

Inflammasome activation has been shown to regulate both innate and adaptive immune responses. It is important to investigate whether immune-enhancing natural products can also activate inflammasome. The current study examined the potential of protein-bound polysaccharide-K (PSK), a hot water extract from Trametes versicolor, to activate inflammasome. Using THP-1 cells, we have demonstrated that PSK induces both pro-IL-1β and mature IL-1β in THP-1 cells in a caspase 1- and NLRP3-dependent manner. PSK also induces IL-1β and IL-18 in human PBMC. Cathepsin B is required for PSK-induced inflammasome activation as CA-074-Me, a cathepsin B inhibitor, significantly decreased PSK-induced IL-1β. PSK induces NLRP3 at both mRNA and protein level. Comparison of PSK-induced IL-1β in bone marrow-derived macrophages from wild type C57BL/6 mice, TLR2(-/-), P2X7R(-/-) and NLRP3(-/-) mice demonstrated that PSK-induced IL-1β is dependent on both TLR2 and NLRP3. P2X7R is not required for PSK-induced inflammasome activation, but enhances PSK-induced caspase-1 activation and IL-1β induction. Altogether, these results demonstrated that PSK induces inflammasome activation and production of IL-1β in a TLR2- and NLRP3-dependent mechanism. These results provide novel insights into the mechanisms of the immune modulatory effects of PSK.

Up Close and Personal with Cancer Unlocking Medicine's Deepest Mystery Alfred A. Knopf, New York, 2013. 299 pp. $27.95, C$32. ISBN 9780307595140. Bodley Head, London. £18.99. ISBN 9781847921666

Johnson weaves together a memoir of his wife's illness and his personal investigation into what is and is not known about cancer.

A multiantigen vaccine targeting neu, IGFBP-2, and IGF-IR prevents tumor progression in mice with preinvasive breast disease

A multiantigen multipeptide vaccine, targeting proteins expressed in preinvasive breast lesions, can stimulate type I CD4(+) T cells which have been shown to be deficient in both patients with breast cancer and mice that develop mammary tumors. Transgenic mice (TgMMTV-neu) were immunized with a multiantigen peptide vaccine specific for neu, insulin-like growth factor-binding protein 2 and insulin-like growth factor receptor-I at a time when some of the animals already had preinvasive lesions (18 weeks of age). Although immunization with each individual antigen was partially effective in inhibiting tumor growth, immunization with the multiantigen vaccine was highly effective, blocking development of palpable lesions in 65% of mice and slowing tumor growth in the infrequent palpable tumors, which did arise. Protection was mediated by CD4(+) T cells, and the few slow-growing tumors that did develop demonstrated a significant increase in intratumoral CD8(+) T cells as compared with controls (P = 0.0007). We also combined the vaccine with agents that were, by themselves, partially effective inhibitors of tumor progression in this model; lapatinib and the RXR agonist bexarotene. Although the combination of lapatinib and vaccination performed similarly to vaccination alone (P = 0.735), bexarotene and vaccination significantly enhanced disease-free survival (P < 0.0001), and approximately 90% of the mice showed no pathologic evidence of carcinomas at one year. The vaccine also demonstrated significant clinical efficacy in an additional transgenic model of breast cancer (TgC3(I)-Tag). Chemoimmunoprevention combinations may be an effective approach to breast cancer prevention even when the vaccine is administered in the presence of subclinical disease.

HER-2/neu vaccine-primed autologous T-cell infusions for the treatment of advanced stage HER-2/neu expressing cancers

This phase I study evaluated the feasibility of expanding HER-2/neu (HER2) vaccine-primed peripheral blood T-cells ex vivo and assessed the safety of T-cell infusions. Eight patients with HER2(+) treatment refractory metastatic cancers were enrolled. T-cells could be expanded to predefined parameters in seven patients (88%). Ninety-two percent of adverse events were grade 1 or 2. Three of seven patients developed infusion-related inflammatory reactions at their disease sites. HER2-specific T-cells significantly increased in vivo compared to pre-infusion levels (p = 0.010) and persisted in 4/6 patients (66%) over 70 days after the first infusion. Partial clinical responses were observed in 43% of patients. Levels of T-regulatory cells in peripheral blood prior to infusion (p < 0.001), the level of HER2-specific T-cells in vivo (p = 0.030), and development of diverse clonal T-cell populations (p < 0.001) were associated with response. The generation of HER2 vaccine-primed autologous T-cells for therapeutic infusion is feasible and well tolerated. This approach provides a foundation for the application of T-cell therapy to additional solid tumor types.

Abstract IA27: Immunomodulation of breast cancer

Breast cancer is immunogenic and there is significant evidence that as breast cancer develops, tumors elicit an adaptive immune response. T-cells infiltrate most breast cancers and in several studies, the presence of elevated intratumoral CD8+ T-cells or elevated CD8+ T-cells in conjunction with a limited T-regulatory cell infiltration is associated with a favorable prognosis. Moreover, patients with breast cancer have been shown to develop immunity against specific proteins expressed by their tumors. Recent studies demonstrate that the development of humoral immunity directed against tumor associated antigens can be detected prior to a breast cancer diagnosis indicating the ability of the immune system to act as a sensor for exposure to aberrantly expressed proteins.

Cellular immunity, directed against breast cancer antigens and elicited by exposure to malignancy, is present even while the disease progresses. The endogenous breast cancer specific cellular immune response is often of a Type II phenotype eliciting primarily antibody immunity rather than cytotoxic T-cells. Furthermore, type II cytokines secreted by T-cells actively dampen the development of a CD8 T-cell response. Type I cytokines, such as interferon gamma or TNF-alpha, are needed to activate antigen presenting cells allowing the presentation of tumor specific antigens via cross-priming, the primary mechanism by which cancer is recognized by T-cells. Immune cells which secrete Type I cytokines are rarely detected or found only in limited numbers in the tumors of most breast cancer patients.

Several therapeutic modalities are under development and designed to increase or stimulate Type I T-cells capable of homing to breast tumors. Active immunization, targeting specific breast cancer antigens, has been shown to directly modulate the breast cancer microenvironment by enhancing cross-priming resulting in the development of epitope spreading. The identification of developing immunity against multiple tumor antigens during the course of treatment has been associated with a survival benefit after vaccination targeting HER-2/neu (HER2). High levels of vaccine induced Type I HER2 specific T-cells have been shown to be inversely associated with serum TGF-beta levels in patients with advanced stage breast cancer. Significantly increasing the number of Type I T-cells targeting breast cancer, via strategies such as adoptive T-cell therapy, has been associated with a measurable clinical response in advanced stage breast cancer. Ex vivo expansion of HER2 specific Th1 cells, after vaccine priming, and infusion of those cells into patients resulted in a 40% clinical response rate in patients with Stage IV treatment-refractory breast cancer. After infusion of Type I HER2 positive T-cells, responding patients developed multiple clonal CD4+ and CD8+ T-cell populations in their peripheral blood, which may be an indication of epitope spreading. The level of HER2 specific T-cells achieved in vivo and the development of a diversity of clonal T-cells was significantly associated with clinical response.

Although breast cancer specific Type I T-cells may not be found in the malignancy at the time of diagnosis, such cells can be induced. The ability to circumvent the immune suppressive microenvironment opens the door for combination immune based therapies utilizing checkpoint blocking antibodies or specific chemotherapies shown to modulate immune suppression to further enhance the number and function of tumor specific Type I T-cells.

Citation Format: Mary L. Disis. Immunomodulation of breast cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr IA27.

Expanding assessments of translational research programs: supplementing metrics with value judgments

The University of Washington (UW) Institute for Translational Health Sciences (ITHS), funded by a Clinical and Translational Sciences Award program, has supplemented its initial Kellogg Logic Model–based program evaluation with the eight judgment-based evaluative elements of the World Health Organization’s (WHO) Health Services Assessment Model. This article describes the relationship between the two models, the rationale for the decision to supplement the evaluation with WHO evaluative elements, the value-added results of the WHO evaluative elements, and plans for further developing the WHO assessments.

The invisible arm of immunity in common cancer chemoprevention agents

Immunoprevention refers to a strategy of preventing pathogen-associated and spontaneous cancers through the use of vaccines, antibodies, and immune modulators. Immune modulators function by enhancing the endogenous ability of the immune system to monitor for malignancy, so-called "immunosurveillance." There is growing evidence that many of the most promising cancer chemoprevention agents including aspirin, COX-2 inhibitors, aromatase inhibitors, and bisphosphonates mediate their effects, in part, by enhancing immunosurveillance and reversing the immune evasive mechanisms that premalignant lesions use. In the following review, we introduce critical components of the human immune surveillance system-dendritic cells, T cells, and immune suppressive cells-and discuss the emerging data suggesting that common chemoprevention agents may modulate the function of these immunologic cells.

Identification of putative immunologic targets for colon cancer prevention based on conserved gene upregulation from preinvasive to malignant lesions

The length of time required for preinvasive adenoma to progress to carcinoma, the immunogenicity of colorectal cancer (CRC), and the identification of high-risk populations make development and testing of a prophylactic vaccine for the prevention of CRC possible. We hypothesized that genes upregulated in adenoma relative to normal tissue, which maintained increased expression in CRC, would encode proteins suitable as putative targets for immunoprevention. We evaluated existing adenoma and CRC microarray datasets and identified 160 genes that were ≥2-fold upregulated in both adenoma and CRC relative to normal colon tissue. We further identified 23 genes that showed protein overexpression in colon adenoma and CRC based on literature review. Silencing the most highly upregulated genes, CDH3, CLDN1, KRT23, and MMP7, in adenoma and CRC cell lines resulted in a significant decrease in viability (P < 0.0001) and proliferation (P < 0.0001) as compared to controls and an increase in cellular apoptosis (P < 0.05 for CDH3, KRT23). Results were duplicated across cell lines representing microsatellite instability, CpG island methylator, and chromosomal instability phenotypes, suggesting immunologic elimination of cells expressing these proteins could impact the progression of all CRC phenotypes. To determine whether these proteins were immunogens, we interrogated sera from early stage CRC patients and controls and found significantly elevated CDH3 (P = 0.006), KRT23 (P = 0.0007), and MMP7 (P < 0.0001) serum immunoglobulin G in cases as compared to controls. These data show a high throughput approach to the identification of biologically relevant putative immunologic targets for CRC and identified three candidates suitable for vaccine development.

Protein-bound polysaccharide activates dendritic cells and enhances OVA-specific T cell response as vaccine adjuvant

Protein-bound polysaccharide-K (PSK) is a hot water extract from Trametes versicolor mushroom. It has been used traditionally in Asian countries for its immune stimulating and anti-cancer effects. We have recently found that PSK can activate Toll-like receptor 2 (TLR2). TLR2 is highly expressed on dendritic cells (DC), so the current study was undertaken to evaluate the effect of PSK on DC activation and the potential of using PSK as a vaccine adjuvant. In vitro experiments using mouse bone marrow-derived DC (BMDC) demonstrated that PSK induces DC maturation as shown by dose-dependent increase in the expression of CD80, CD86, MHCII, and CD40. PSK also induces the production of multiple inflammatory cytokines by DC, including IL-12, TNF-α, and IL-6, at both mRNA and protein levels. In vivo experiments using PSK as an adjuvant to OVAp323-339 vaccine showed that PSK as adjuvant leads to enlarged draining lymph nodes with higher number of activated DC. PSK also stimulates proliferation of OVA-specific T cells, and induces T cells that produce multiple cytokines, IFN-γ, IL-2, and TNF-α. Altogether, these results demonstrate the ability of PSK to activate DC in vitro and in vivo and the potential of using PSK as a novel vaccine adjuvant.

Proteomic profiling of the autoimmune response to breast cancer antigens uncovers a suppressive effect of hormone therapy

PURPOSE

Proteomics technologies are well suited for harnessing the immune response to tumor antigens for diagnostic applications as in the case of breast cancer. We previously reported a substantial impact of hormone therapy (HT) on the proteome. Here, we investigated the effect of HT on the immune response toward breast tumor antigens.

EXPERIMENTAL DESIGN

Plasmas collected 0-10 months prior to diagnosis of ER+ breast cancer from 190 postmenopausal women and 190 controls that participated in the Women's Health Initiative Observational Study were analyzed for the effect of HT on IgG reactivity against arrayed proteins from MCF-7 or SKBR3 breast cancer cell line lysates following extensive fractionation.

RESULTS

HT user cases exhibited significantly reduced autoantibody reactivity against arrayed proteins compared to cases who were Not Current users. An associated reduced level of IL-6 and other immune-related cytokines was observed among HT users relative to nonusers.

CONCLUSION AND CLINICAL RELEVANCE

Our findings suggest occurrence of a global altered immune response to breast cancer-derived proteins associated with HT. Thus a full understanding of factors that modulate the immune response is necessary to translate autoantibody panels into clinical applications.

Abstract 3986: Protein-bound polysaccharide induces IL-1β via NLRP3 inflammasome activation

Protein-bound polysaccharide-K (PSK) is a hot water extract from Trametes Versicolor mushroom. It is widely used in Asian countries for its immune enhancing and anti-cancer potential. We have recently reported that PSK activates TLR2 and has CD8 T cell- and NK cell- dependent anti-tumor activity. PSK stimulates the production of multiple pro-inflammatory cytokines, including IL-1β, the production of which requires both TLR and inflammasome activation. The current study was undertaken to investigate the mechanism by which PSK activates inflammasome and induces IL-1β. RT-PCR and Western blot analyses showed that PSK induces pro-IL-1β in a dose- and time- dependent manner. PSK activates caspase-1 and pre-incubation with z-VAD-FMK, a caspase inhibitor, abolishes PSK-induced IL-1β. Comparison of THP-1 cells and THP-1 cells deficient for NLRP3 demonstrated that PSK-induced IL-1β production requires NLRP3 inflammasome. PSK also up-regulates the expression of NLRP3 mRNA. Further experiments were performed to investigate whether potassium efflux, reactive oxygen species (ROS) generation, or lysosomal perturbation was involved in PSK-induced NLRP3 inflammasome activation. Results showed that CA-074-Me, a cathepsin B inhibitor, significantly decreased PSK-induced IL-1β, while the production of TNF-α was not affected. Phagocytosis or ROS generation was not required for PSK-induced NLRP3 inflammasome activation. Altogether, our results suggest that PSK-induced IL-1β production is a two step process. Step 1 requires TLR2-dependent induction of pro-IL-1β and upregulation of NLRP3 expression; Step 2 involves NLRP3 inflammasome activation in a cathepsin B-dependent manner. These results provide novel insights into the mechanisms of the immune stimulatory and anti-tumor effects of PSK.

Citation Format: Yi Yang, Carol Inatsuka, Mary L. Disis, Hailing Lu. Protein-bound polysaccharide induces IL-1β via NLRP3 inflammasome activation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3986. doi:10.1158/1538-7445.AM2013-3986

Three-dimensional scaffolds to evaluate tumor associated fibroblast-mediated suppression of breast tumor specific T cells

In the tumor microenvironment, the signals from tumor-associated fibroblasts (TAF) that suppress antitumor immunity remain unclear. Here, we develop and investigate an in vitro three-dimensional (3D) scaffold model for the novel evaluation of TAF interaction with breast tumor cells and breast specific, neu antigen (p98) reactive T cells. Breast cancer cells seeded on 3D chitosan-alginate (CA) scaffolds showed productive growth and formed distinct tumor spheroids. Antigen specific p98 T cells, but not naïve T cells, bound significantly better to tumor cells on scaffolds. The p98 T cells induced potent tumor cell killing but T helper cell cytokine function was impaired in the presence of TAF coseeding on scaffolds. We found that the immunosuppression was mediated, in part, by transforming growth factor beta (TGF-b) and interleukin-10 (IL-10). Therefore, TAF appear capable of inducing potent T cell suppression. CA scaffolds can provide clinically relevant findings prior to preclinical testing of novel immunotherapies.

Abstract P2-15-02: The efficacy of recruitment and retention strategies for research subjects in an early phase investigator-initiated breast cancer trial

Background: One of the biggest challenges faced by investigators is the implementation of effective strategies to improve the recruitment and retention of research participants. This is especially true for investigator-initiated, federally funded (e.g. NIH and DOD), early phase clinical trials that involve the treatment of serious diseases such as metastatic breast cancer (MBC). These studies may face additional barriers to participation since patients have often already undergone maximal treatment and are usually not in a financial position that for allows the travel and lodging necessary to receive further investigative treatment. Moreover, efficacy and toxicology in early phase clinical trials are unknown. Thus, when study budget constraints do not allow monetary incentives to participation, it is difficult to provide motivation for patients to enroll and remain adherent to the protocol requirements. However, many MBC patients are motivated to join clinical trials for altruistic purposes alone, and evidence supports that the researcher-patient relationship may be the most important factor in clinical trial participation. Recognizing that many patients are willing to participate if provided the appropriate resources despite limited monetary incentives, we developed a system to improve patient recruitment and retention to our studies, which are primarily federally funded. We report here on the strategies developed and used by our group to recruit and retain patients in a federally-funded investigator-initiated phase I/II vaccine study in MBC patients.

Methods: This study was funded by the NIH/NCI and involved infusion of HER2 specific T cells in HER2+ MBC patients after completing in vivo priming with a HER2 vaccine. It required 11 visits to Seattle, Washington. Working with agencies that offer free services to patients enrolled in clinical trials, a list of available resources was compiled and a visit flowchart with specific information on travel and lodging resources (e.g. Angel Flights and ACS sponsorship), local transportation and entertainment was developed. During screening, patients were given the list of resources and trial information. An email system was used to quickly communicate and follow-up with patients. Eligible patients were given the visit flowchart to help with their planning of study visits. An enrollment packet was provided at the first visit with a calendar to keep track of the visit schedule. Coordination of care between the patient's primary oncologist and the research staff was maintained throughout the study.

Results: 17 of 19 patients enrolled were not from Washington State. Two out-of-state patients withdrew early from the trial for reasons unrelated to disease progression or toxicity; one subject completed 8 visits and enrolled in another study and the other completed 2 visits and discontinued the trial to resume chemotherapy.

Conclusion: We have developed a successful system to enroll and retain patients in a trial requiring multiple study visits. Development and implementation of site-specific standard procedures are critical to improve study participation and retention, especially when patients receive no financial benefit.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-15-02.

Abstract P5-16-04: A phase I study of a DNA plasmid based vaccine encoding the HER-2/neu intracellular domain in subjects with HER2+ breast cancer

HER2+ breast cancer (BC) is associated with early disease relapse, usually to distant sites. This would suggest relapse is due to residual microscopic disease. Generation of vaccine-induced HER2-specific CD4+ T helper immunity (Th1) may result in immunologic eradication of residual HER2+ tumor cells and subsequent development of immunologic memory and epitope spreading (ES), which has been associated with a survival benefit in vaccinated BC patients. We have shown HER2 peptide-based vaccines can generate immunity in BC however, more recently we developed a plasmid DNA based vaccine (pNGVL3-hICD) which may have additional advantages over synthetic peptides. DNA vaccines offer a strategy to immunize against multiple tumor antigens and are able to elicit both CTL and Th1 immunity. Plasmid DNA can also remain at the vaccine site, providing a constant source of antigen. Intradermal (i.d.) delivery of DNA vaccines with GM-CSF as adjuvant may enhance immunogenicity due to local influx of dermal Langerhans cells. We have recently completed a phase I trial utilizing pNGVL3-hICD in optimally treated stage III and IV HER2+ BC patients and have defined vaccine safety profile, optimal dose and schedule; and demonstrated vaccine biologic activity.

Methods: A total of 66 subjects with stage III and IV HER2+ BC in complete remission were enrolled sequentially into 1 of 3 pNGVL3-hICD dose arms (22 subjects/arm): Arm 1=10µg, Arm 2=100 µg, and Arm 3 = 500µg. All vaccines were admixed with 100µg GM-CSF and given i.d. monthly for a total of 3 vaccines. Toxicity was assessed at baseline, during vaccination and at follow-up. Immune responses to HER ICD and ECD were assessed with IFN-γ ELISPOT at baseline and serially through week 60 post-vaccination. Linear regression analysis was used to compare differences in immune responses from baseline over the whole study period between dose arms. Vaccine site skin biopsies and peripheral lymphocytes were serially analyzed for plasmid persistence via RT-PCR.

Results: 64 subjects (20 in Arm 1; 22 in Arm 2; 22 in Arm 3) completed 3 vaccines. Age, stage/status, number of previous chemotherapy regimens, and use of bisphosphonate and trastuzumab therapies was similar across dose arms. Vaccine-related toxicity was primarily Grade 1/2 injection site reactions, myalgias, arthralgias and not significantly different between arms; no cardiac or grade IV toxicity was observed. Immune responses to HER2 ICD were significantly better in Arms 2 and 3 vs Arm 1 (p = 0.001 and 0.002, respectively) but not statistically different between Arms 2 and 3. 38 patients had DNA plasmid persistence at the vaccination site with no difference between arms. There has been no detection of DNA plasmid in lymphocytes from patients in all arms. Analyses of survival and ES (HER ECD immune responses) are on-going and will be presented.

Conclusions: pNGVL3-hICD was safe and effectively induced persistent HER2 ICD specific Th1 immunity without increased cardiac toxicity. Moreover, immunity was present more than 1 year after end of vaccination, indicative of vaccine-induced immunologic memory.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-16-04.

Abstract OT3-1-02: Phase II randomized study of combination immunotherapy with or without Polysaccharide Krestin (PSK®) concurrently with a HER2 ICD peptide-based vaccine and trastuzumab in patients with stage IV breast cancer

Background: Endogenous immunity in patients with HER2+ metastatic breast cancer (MBC) is likely dampened by an immune-suppressive tumor microenvironment and not sufficient to control tumor growth. Thus, most patients have disease relapse after achieving complete remission with standard therapies. Immunomodulation directed at enhanced stimulation of tumor specific immunity could result in immunologic eradication of residual HER2+ tumor cells and prevent BC relapse. We have shown PSK to be a potent TLR-2 agonist that stimulates both innate and adaptive immunity in a BC mouse model. Additionally, we have shown combination immunotherapy with HER2 peptide vaccines and trastuzumab (TRAZ) to be safe and able to elicit HER2 specific Th1 immunity and epitope spreading (ES) which has been associated with survival in vaccinated patients. Lastly, decreased serum TGF-β elicited by HER2 vaccination correlates with Th1 ES and may serve as a biomarker to predict cancer vaccine efficacy. We hypothesize that PSK, when given with TRAZ can augment vaccine induced HER2 specific TH1 immunity and prevent disease relapse in patients with optimally treated HER2+ MBC.

Trial design: Phase II randomized two-arm clinical trial. Patients will be enrolled and randomly assigned in equal numbers to 1 of 2 arms (15 patients/arm) as follows: Arm 1:HER2 ICD vaccine, TRAZ and placebo or Arm 2:HER2 ICD vaccine, TRAZ and PSK. All patients will receive 3 monthly HER2 ICD vaccines plus TRAZ and 4 months of concomitant PSK or placebo. Serial blood draws for immunologic monitoring will be done.

Eligibility criteria: Patients with Stage IV HER2+ BC who have been treated with definitive therapy and are: (1) without evidence of disease or have stable-bone only disease, (2) receiving TRAZ monotherapy, and (3) without clinically significant autoimmune disease. Patients must have normal LVEF per MUGA scan or echocardiogram.

Aims: (1) Evaluate safety of PSK when given with a HER2 vaccine and TRAZ (2) Evaluate the effect of PSK on serum TGF-β levels when given with a HER2 vaccine and TRAZ and (3) Evaluate the effect of PSK on intermolecular ES when given with a HER2 vaccine and TRAZ. A secondary objective is to evaluate progression free survival (PFS) and overall survival (OS).

Statistical methods: (1) Toxicity will be determined by clinical and chemical parameters and grading will be done per CTEP CTCAE 4.0.; (2) Evaluation of TGF-β levels, pre and post-PSK treatment will be assessed with linear regression models; and analysis of multiple post-baseline measurements will be performed using generalized estimating equations; (3) A positive antigen-specific immune response will be defined as a precursor frequency &gt;1:20,000 antigen-specific peripheral blood mononuclear cells. Differences in the levels of HER2 immunity will be evaluated between arms using a two-tailed T test. The degree of ES in each arm will be evaluated with generalized linear modeling; (4) Large differences in PFS and OS observed between groups will be noted and described.

Target accrual: 30 patients.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr OT3-1-02.

Values in translation: how asking the right questions can move translational science toward greater health impact

The speed and effectiveness of current approaches to research translation are widely viewed as disappointing given small gains in real population health outcomes despite huge investments in basic and translational science. We identify critical value questions-ethical, social, economic, and cultural-that arise at moments throughout the research pathway. By making these questions visible, and promoting discussion of them with diverse stakeholders, we can facilitate handoffs along the translational pathway and increase uptake of effective interventions. Who is involved with those discussions will determine which research projects, populations, and methods get prioritized. We argue that some upfront investment in community and interdisciplinary engagement, shaped by familiar questions in ethics, social justice, and cultural knowledge, can save time and resources in the long run because interventions and strategies will be aimed in the right direction, that is, toward health improvements for all.