Abstract PD12-05: PD12-05 Adipocyte directed vaccination to reduce the risk of breast cancer

Background: Obesity is an important risk factor for breast cancer and women with metabolic syndrome may be at the highest risk. Infiltration of CD8 T-cells into fat is an early event in obesity. Type I cytokines secreted by CD8 T-cells upregulate costimulatory molecules on enlarged adipocytes. The adipocytes, now antigen presenting cells, further stimulate Type I T-cell activation. The resulting T-cells compete for glucose and fatty acids which leads to metabolic dysfunction in both the adipose tissue and the T-cells themselves. The T-cells are not able to maintain tumor immune surveillance and secretion of adipokines promotes malignant transformation. Immunologic memory prevents inflammation from resolving even if an individual becomes normal weight. Strategies to increase Type II (anti-inflammatory) T-cells in inflamed adipose could have clinical benefit. Methods: We developed a method of CD4 epitope identification that includes functional screening for Th1 or Th2 epitopes. We use a multi-algorithm approach to ensure responsiveness across diverse HLA alleles. We identified Th2 selective epitopes associated with high IL-10 secretion for 6 adipocyte associated antigens that become overexpressed in inflamed adipocytes (IGF-IR, HIF-1a, DUSP1, FABP4, PAI-1 and ATGL). The epitopes were highly homologous between mouse and man (median 100% (range-82-100%). When the epitopes were used to immunize mice, all antigens generated a significant IL-10 response compared to control (p< 0.05). We questioned whether our “adipocyte directed” vaccine (ADVac) could prevent the development of breast cancer in obese mice. Results: First, C57BL/6 mice were fed a high fat high sucrose (HFHS) diet or normal chow. When mice became obese, vaccination with ADVac or adjuvant alone (Alum) was initiated. Four weeks after the final vaccine, visceral adipose tissue showed significantly fewer CD8 T-cells in the obese mice immunized with ADVac as compared to the control, p=0.0011. The decrease in CD8 T-cells was specific for adipose tissue as no change was observed in matched spleen. There was a significant increase in T-regulatory cells in the adipose tissue of mice immunized with ADVac as compared to control, p=0.031. Two weeks after the final vaccine, a glucose tolerance test (GTT) and insulin tolerance (ITT) showed blood glucose concentrations were significantly lower at all time points for the ADVac-immunized obese mice as compared to the control obese mice (p< 0.01 for all). TgMMTV-neu develop aggressive breast cancer when made obese. Ten-week old TgMMTV-neu mice were fed a HFHS diet for 4 weeks, then randomized into 2 cohorts when obese, one cohort receiving the adjuvant only (Alum) and one receiving ADVac. Mice were sacrificed at 31 weeks of age when all controls had developed tumor. ITT showed the glucose levels in the blood were significantly lower in the ADVac group as compared to control (p< 0.0001). Fewer CD8 T-cells were observed in mammary adipose tissue of AdVac immunized mice compared to control (p=0.001). There was significantly less leptin detected in the serum of ADVac vaccinated mice compared to Alum immunized, p=0.024. The median age of tumor development was 25 weeks in controls and 29 weeks in the immunized group (p=0.009). Sixty percent (9/15) of the vaccinated mice were tumor free at study termination, whereas 100% of the control mice had developed tumor. Conclusions: ADVac represents the first vaccine to lower breast cancer risk in obesity. Vaccination corrected metabolic dysfunction as evidenced by reversal of diabetes and prevented breast cancer in the majority of obese ADVac immunized mice. Further studies are ongoing evaluating the systemic distribution of ADVac specific T-cells and the safety of the approach.

Citation Format: Mary Disis, Lauren Corulli, Erin R. Rodmaker, Denise Cecil. PD12-05 Adipocyte directed vaccination to reduce the risk of breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD12-05.

Abstract IA016: Vaccine approach for the interception of colon cancer

This year, in the US, an estimated 150,000 people will be diagnosed with colon cancer and ~52,000 will die of the disease. A vaccine approach is well suited to colon cancer prevention. First, a limited number of immunizations can be given over a short period of time to achieve a desired immune response. If immunologic memory develops, antigen specific T-cells will persist in the body for years, ready to be deployed when aberrant cells are detected. Finally, there are several well-defined high-risk populations that would be suitable for testing a preventative colon cancer vaccine including individuals (1) with a hereditary genetic syndrome such as familial adenomatous polyposis, (2) with a history of inflammatory bowel disease such as Crohn’s disease or ulcerative colitis, and (3) those with a history of hyperplastic colonic polyps. Vaccines targeting virally mediated cancers are effective, in part, because T-cells are primed to proteins involved in oncogenesis. The most common type of colon adenoma and invasive cancer associated antigens are non-mutated growth-related proteins that become markedly overexpressed in the disease state. Genes which are aberrantly up-regulated and conserved from adenoma to invasive colon carcinoma may encode overexpressed proteins that are associated with colon cancer initiation. Evaluating gene expression data derived from over 600 colorectal cancers, matched normal tissues, and colon adenomas we identified 160 genes overexpressed in the majority of adenomas and early-stage colon cancers, but not in normal tissues. Using siRNA screening we demonstrated 35 of those genes, when silenced, resulted in apoptosis or inhibition of growth of colon cancer cells and an adenoma cell line but not a non-neoplastic colon cell line. Of those genes, 16 have been shown to encode proteins that are overexpressed in both adenomas and colon cancer and are associated with disease progression and over a third of these proteins are immunogenic. These proteins could serve as potential candidate antigens for inclusion in a multi-antigen vaccine. Recently, we have identified epitopes within the natural sequences of non-mutated tumor antigens that only generate Th1 (Th1 selective) antigen specific T-cells. This discovery and the development of high throughput methods to both identify and screen putative Class II binding peptides for Th selective function has allowed us to develop antigen specific Th1 selective vaccines. A vaccine targeting CDC25B, COX2, and EGFR can inhibit intestinal tumor formation in both APCmin mice and mice with tumor induced by AOM. Concomitant use of NSAIDs potentiates the immune response generated with vaccination. The anti-tumor response observed after vaccination is significantly correlated with elevated CD8 T-cells found in the lesions and induced by immunization as well as high magnitude antigen specific T-cells identified in the spleen. These data validate a genomic approach to antigen discovery and anti-tumor efficacy of Th1 selective vaccines for colon cancer prevention.

Citation Format: Mary Disis, Ying Liu, Lauren Corulli, Erin Rodmaker, Denise Cecil. Vaccine approach for the interception of colon cancer. [abstract]. In: Proceedings of the AACR Special Conference: Precision Prevention, Early Detection, and Interception of Cancer; 2022 Nov 17-19; Austin, TX. Philadelphia (PA): AACR; Can Prev Res 2023;16(1 Suppl): Abstract nr IA016.

Abstract OT1-16-01: A multicenter phase II study of vaccines to prevent recurrence in patients with HER-2 positive breast cancer

Background: HER2-positive breast cancer patients are commonly treated with neoadjuvant therapy including HER2-targeted therapy. Patients who have residual invasive disease have less favorable outcomes with an increased risk of recurrent disease than patients with complete pathologic response (pCR). It has also been observed that these non-pCR patients have low or absent anti-HER-2 CD4 Th1 responses. We hypothesized that correcting the anti-HER-2 CD4 Th1 response using vaccines will increase interferon gamma production which we have shown is a potent inducer of apoptosis and senescence in HER2-positive breast cancer. This study will be evaluating safety and immunogenicity of two vaccines (multivalent anti-oncodriver DNA vaccine (WOKVAC) or HER-2-pulsed dendritic cell vaccine (DC1)). Methods: This is a multi-center, phase 2, randomized study to determine the safety and tolerability of HER2 vaccines (DC1 and WOKVAC), assess immunogenicity, and evaluate recurrence free survival. Patients with HER2-positive early breast cancer (stage I-III) are eligible if they have residual invasive disease in the breast or axilla at surgery after receiving neoadjuvant chemotherapy plus HER2 -targeted therapy. Patients are randomly assigned in a 1:1 ratio to receive 1 of 2 adjuvant HER2 vaccines, either DC1 or WOKVAC for 1 year. A permuted-block randomization scheme was used with stratification according to residual cancer burden (RCB) (1+2 vs 3). The primary end points are safety and immunogenicity (immune response rate measured by ELISPOT). Each treatment arm will be assessed separately. Any statistical comparison between arms is purely exploratory, as this study is neither designed nor powered for comparative hypotheses. Secondary endpoints include recurrence-free survival. Exploratory analyses include the assessment of prognostic and predictive biomarkers including circulating tumor cells, serum HER2 levels, and other immune markers. The enrollment began in 2018 and we plan to accrue the total of 110 patients. ClinicalTrials.gov Identifier: NCT03384914

Citation Format: Hyo S Han, Mary Disis, Robert Wesolowski, Carla Fisher, Shipra Gandhi, Nancy Chan, William Gwin, Keerthi Gogineni, Rosemarie Mick, Christina Sierra Rodriguez, Deanna Hogue, Hien Liu, Ricardo Costa, Brian Czerniecki. A multicenter phase II study of vaccines to prevent recurrence in patients with HER-2 positive breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-16-01.

Culture conditions promoting innate immunity and homeostatic proliferation generate highly enriched, MUC1- or HER2/neu-specific CD4+ and CD8+ T cells (P4419)

Although tumors from melanoma patients can often provide a source of therapeutically active T cells for adoptive therapy, it has historically proved challenging to employ peripheral blood as the T cell source for any type of cancer. We have observed nonetheless that HER2-specific T cells can be Ag-driven and enriched in culture when PBMCs from HER2-vaccinated breast cancer patients are treated with exogenous IL12. We hypothesized that stimulating innate immunity could further improve PBMC cultures by activating the DC subpopulation more effectively than adding exogenous rIL12. Bulk PBMC exposure to optimized TLR agonists produced vast quantities of IL12 and IL23, and upregulated HLA-DR, B7.1 and CD40 in the DC subpopulation, effects not produced by exogenous IL12. Subsequent IL7 exposure emulated homeostatic proliferation, selectively causing the Ag-driven T cell subset both to proliferate faster and to strongly resist apoptosis. Ag-specificity within two weeks approached 80-100% of both CD4+ and CD8+ T cells for recall Ags and 1-15% for a wide array of MUC1- and HER2-derived peptides, including the ability to distinguish glycoforms. Culture-expanded T cells retained a young CD28+/CD56- phenotype, uniformly expressed ROR-γ during culture, variably produced IL-2 and/or IL-17, and uniformly expressed T-bet and secreted IFN-γ when reexposed to Ag. Such T1/T17 bipotency may be ideal for anti-tumor adoptive therapy and highly efficient for use in Ag discovery.

Abstract 523: γα T cells are activated by protein-bound polysaccharide krestin (PSK) and contribute to the antitumor effect of PSK

Gamma delta (γδ) T cells play an important role in anti-tumor immunity, and novel methods to augment γδ T cell function are highly desired. It has recently been shown that toll-like receptor (TLR) agonists may modulate the function of γδ T cells, so we questioned whether protein-bound polysaccharide krestin (PSK), a mushroom extract with TLR2 agonist activity, can activate γδ T cell. Using splenocytes from neu-transgenic mice, we found that γδ T cells produce IFN-γ after PSK treatment and have up-regulated expression of CD25 and CD69. The expression of CD107a in γδ T cells was also enhanced by PSK. To investigate whether the effect of PSK on γδ T cells is direct or indirect via activation of dendritic cells (DC), purified γδ T cells were cultured either alone or together with bone marrow derived DC (BMDC) in a co-culture or trans-well system and then stimulated with PSK. Results showed that direct cell-to-cell contact between γδ T cells and DC is required for optimal activation of γδ T cells. In the absence of DC, PSK can co-stimulate γδ T cells with anti-γδ TCR or anti-CD3 mAb. Oral administration of PSK in neu-transgenic mice with implanted breast tumors resulted in increased percentage of γδ T cells among splenocytes and increased expression of NKG2D on γδ T cells. Depleting γδ T cells during PSK treatment decreased the anti-tumor effect of PSK. All together, these results demonstrated that γδ T cells are activated by PSK and contribute to the anti-tumor effect of PSK.

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 523. doi:1538-7445.AM2012-523

Preparedness of the CTSA's structural and scientific assets to support the mission of the National Center for Advancing Translational Sciences (NCATS)

The formation of the National Center for Advancing Translational Sciences (NCATS) brings new promise for moving basic science discoveries to clinical practice, ultimately improving the health of the nation. The Clinical and Translational Science Award (CTSA) sites, now housed with NCATS, are organized and prepared to support in this endeavor. The CTSAs provide a foundation for capitalizing on such promise through provision of a disease-agnostic infrastructure devoted to clinical and translational (C&T) science, maintenance of training programs designed for C&T investigators of the future, by incentivizing institutional reorganization and by cultivating institutional support.

Concordant release of glycolysis proteins into the plasma preceding a diagnosis of ER+ breast cancer

Although the identification of peripheral blood biomarkers would enhance early detection strategies for breast cancer, the discovery of protein markers has been challenging. In this study, we sought to identify coordinated changes in plasma proteins associated with breast cancer based on large-scale quantitative mass spectrometry. We analyzed plasma samples collected up to 74 weeks before diagnosis from 420 estrogen receptor (ER)(+) cases and matched controls enrolled in the Women's Health Initiative cohort. A gene set enrichment analysis was applied to 467 quantified proteins, linking their corresponding genes to particular biologic pathways. On the basis of differences in the concentration of individual proteins, glycolysis pathway proteins exhibited a statistically significant difference between cases and controls. In particular, the enrichment was observed among cases in which blood was drawn closer to diagnosis (effect size for the 0-38 weeks prediagnostic group, 1.91; P, 8.3E-05). Analysis of plasmas collected at the time of diagnosis from an independent set of cases and controls confirmed upregulated levels of glycolysis proteins among cases relative to controls. Together, our findings indicate that the concomitant release of glycolysis proteins into the plasma is a pathophysiologic event that precedes a diagnosis of ER(+) breast cancer.

Abstract 2683: Identification of tumor antigens in neu transgenic mice as diagnostic targets for the early detection of human breast cancer

Tumor antigens, expressed early in disease, which can induce specific antibody response could serve as biomarkers for early detection of human breast cancer. However, the ability to obtain sera from women prior to the development of breast cancer is limited, which makes it difficult to identify early antigens directly from breast cancer patients. Transgenic mouse models have been proved to demonstrate similar antigen repertoire to breast cancer patients. Therefore, we propose to identify early tumor antigens in neu transgenic mice and use them as diagnostic targets for early detection of human breast cancer. We have collected serial sera from neu transgenic mice, sera collected before the animals develop palpable tumor “pre-diagnostic sera”. With serological analysis of recombinant cDNA expression libraries (SEREX) approach, we were able to identify nine tumor antigens from pre-diagnostic sera, Rpl5, TNFaip3/A20, Pdhx, Otud6b, Stk39, Zfp238, Dnajc10, Lgals8 and Vps35. These antigens demonstrated detectable IgG antibody response prior to tumor development in neu transgenic mice. IgM is the first antibody to be produced during a humoral immune response, so we questioned whether including antigen specific IgM with IgG responses could achieve a better diagnostic performance. Firstly, we analyzed receiver-operating-characteristic (ROC) curves of these antigens by IgG and IgM ELISA analysis in neu transgenic mice and 26 FVB control mice. By combining IgG and IgM ELISA, we were able to achieve a higher AUC: Otud6b and Stk39 show an AUC of 0.882, and adding Lgals8 IgG ELISA to this panel can achieve an AUC of 0.924 in discriminating cases from control mice. We documented that these autoantibodies are also detectable in the serum of women with breast cancer and then screened a panel of sera derived from the Women's Health Initiative cohort (samples obtained 6-18 months prior to the development of breast cancer) and case matched controls. We evaluated serum for the presence of IgG and IgM specific autoantibodies to Pdhx, Otud6b, and Stk39. With both IgG and IgM ELISA analysis, a panel combining the three antigens demonstrates an AUC of 0.633 in patients diagnosed within 5 month and an AUC of 0.688 in patients diagnosed within 5-18 month of the blood draw. In summary, we conclude that tumor antigens identified in neu transgenic mouse model can be used for early detection and diagnosis of breast cancer in women. The combination of antigen specific IgG and IgM antibodies may enhance the sensitivity of the assay for early detection.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2683. doi:10.1158/1538-7445.AM2011-2683

Abstract 750: Identification of tumor antigens in transgenic mouse model as vaccine targets for the prevention of human breast cancer

The development of a vaccine to prevent breast cancer would be facilitated if tumor antigens were identified which were associated with the initiation of the malignant transformation. Transgenic mouse models have been proven to demonstrate a similar antigenic repertoire as that seen in breast cancer patients, therefore, we propose to use these models to identify tumor antigens as vaccine targets for breast cancer prevention. We have chosen two mouse models: TgMMTV-neu and TgC3(1)-Tag for study. TgMMTV-neu mouse has a genotype similar to luminal breast cancer and the TgC3(1)-Tag model reflects a basal phenotype of breast cancer. We identified potential vaccine candidate antigens in one of two ways; (1) determining which proteins expressed by the cancer are immunogenic very early in the malignant process by screening pre-diagnostic sera for immunogenicity against tumor cDNA libraries, and (2) injecting parental animals with a syngeneic tumor cell line resulting in “tumor rejection” which we have shown previously is mediated by T cells. To date, we have identified nine pre-diagnostic tumor antigens in TgMMTV-neu mouse; Rpl5, TNFaip3/A20, Pdhx, Otud6b, Stk39, Zfp238, Dnajc10, Lgals8 and Vps35. Moreover, we have identified four rejection antigens in TgC3(1)-Tag mouse; Ddx21, Sfrs11, Edh1 and Tdg. We have initiated vaccination experiments to examine the anti-tumor effect of vaccination with plasmids encoding these antigens. We found that vaccination targeting Ddx21, Dnajc10, and Pdhx mediated tumor growth inhibition in implant models compared with a control group (p<0.01). Our preliminary studies also demonstrate that several of the proteins are immunogenic in humans and we have identified putative promiscuous class II epitopes suitable for screening human PBMC for T cells specific to these proteins.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 750. doi:10.1158/1538-7445.AM2011-750

Abstract SY24-03: Vaccines for the prevention of cancer

Active immunization against infectious disease pathogens has been one of the most successful primary disease prevention modalities to impact human health. In developed countries, common childhood infections such as polio and diphtheria have been nearly eradicated due to standardized childhood vaccination regimens. Stimulating an effective immune response via antigen-targeted immunization will result in the development of immunologic memory allowing neutralizing antibodies or cytotoxic T cells to become mobilized when exposed to the pathogen at a later date. The development of effective vaccines against viruses that are associated with cancer initiation, such hepatitis B/hepatoma and human papilloma virus/cervical cancer, have resulted in a decrease in the incidence of these malignancies. For the majority of common human cancers, however, there are few infectious pathogens identified as direct etiologic agents instrumental in the induction of malignancy.

Tumor-associated proteins that can serve as immunologic targets for active immunization have been identified. The majority of identified tumor antigens are not mutated, but rather, are self proteins. Over the last decade a variety of vaccination strategies have been developed to allow the generation of immunity to these cancer-related proteins and vaccines targeting such antigens have been used for the treatment of a wide variety of human malignancy. Although the clinical success of cancer vaccines has been variable, several observations can be made: (1) functional tumor-specific T cell and antibody immunity can be generated after vaccination in patients with cancer targeting such ubiquitous antigens as hTERT, HER-2/neu, and EGFR, (2) in clinical trials that have enrolled hundreds of patients, immunization against nonmutated self tumor antigens has not resulted in excessive toxicity. Indeed, in most reported studies of vaccination with antigen and standard adjuvants, toxicity is limited to grade 1 and 2 events, and (3) vaccines are most likely to be clinically effective when administered in a minimal disease state. The safety profile of cancer vaccines in the therapeutic setting has allowed the exploration of multiantigen immunization for cancer prevention. Mice that have been genetically engineered to develop specific malignancies offer a model to evaluate cancer prevention approaches, in particular active immunization. Investigations have shown that such murine models often have similar genetic alterations and histology as the human malignancy being modeled. Moreover, the antigenic repertoire in mice is similar to that observed in humans as well.

We have developed a multiantigen polyepitope vaccine targeting immunogenic proteins associated with oncogenesis and assessed whether we could prevent the development of breast cancer in middle-aged TgMMTV-neu mice. The multiantigen vaccine inhibited tumor growth in 50-80% of mice and was superior to individual antigen immunizations in protecting mice against breast cancer (p<0.05). Studies demonstrated that vaccine induced tumor protection was mediated by T cells and even vaccinated mice that were unprotected by immunization and eventually developed tumors demonstrated evidence of high levels of type I immunity, evidence of T cells with potent antitumor activity, and tumor trafficking CD8+ T cells. To determine the cause of vaccine failure, we evaluated the mammary tissue of 18 week old animals at the time of immunization which revealed a significant incidence of subclinical breast tumors, both premalignant and malignant. The addition of bexarotene, a retinoid X receptor (RXR) agonist, to multiantigen vaccination significantly increased the proportion of protected animals and was superior to both bexarotene and vaccine alone in inhibiting the development of breast cancer (p<0.01). There was no evidence of autoimmune toxicity in immunized mice. These data suggest breast cancer vaccines targeting biologically relevant proteins may be an effective approach to the prevention of breast cancer even when administered in the presence of subclinical disease if combined with an antiproliferative agent.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr SY24-03. doi:10.1158/1538-7445.AM2011-SY24-03

Abstract 2415: Evaluation of a DNA vaccine and adjuvant construct for producing anti tumor immunity targeting IGFBP2

DNA based vaccines offer the advantage of stability, low cost, and longer duration of antigen exposure than protein based vaccines. We sought to evaluate strategies to augment the anti tumor potency. Using three immunogenic peptides from the ovarian cancer antigen, human insulin-like growth factor binding protein-2 (IGFBP2) we created a DNA epitope construct that encodes these three peptides in sequence and vaccinated mice with the epitope vaccine or an admixture of the peptides or plasmids expressing either the full length human or mouse genes. Mice received three vaccinations separated by two weeks followed fourteen days later by a lethal injection of syngeneic MMC tumor cells known to express IGFBP2. The DNA epitope vaccine produced a greater level of protection than any of the other constructs proving it to be the best formulation for inducing protective anti tumor responses. Full length human and mouse IGFBP2 DNA constructs induced a similar level of protection as the peptide based vaccine. This IGFBP2 epitope DNA vaccine was then tested in conjunction with plasmids encoding murine GM-CSF and IL-12 either alone or in combination in an identical vaccination strategy. Each genetic adjuvant either alone or in combination improved the level of protection induced by the IGFBP2 DNA epitope vaccine though no difference in tumor protection was seen between adjuvants used either alone or together. Evaluation of the inoculation site revealed a persistence of CD11c+ dendritic cells and CD3+ T cells fourteen days after final vaccination predominantly in mice who received plasmids containing the cytokines versus those who received soluble protein. These data support the use of epitope based DNA vaccines in conjunction with genetic adjuvants for the production of anti tumor efficacy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2415.

Phase I-II Study of Denileukin Diftitox (ONTAK®) in Patients with Advanced Refractory Breast Cancer

Background: CD4+CD25+Foxp3+ regulatory T cells (Tregs) are potent suppressors of CD4+ and CD8+ T cells, produce the immunosuppressive cytokine TGF-β; and as such, may down-regulate immune responses to tumor antigens. Additionally, Tregs are increased in the peripheral blood (PB) and tumors of breast cancer patients; and are associated with poor prognosis. Depletion of PB and tumor-associated Tregs may induce anti-tumor immunity by augmenting anti-tumor effector T cells and enhancing endogenous tumor specific immunity. ONTAK®, a diphtheria/IL-2R fusion protein depletes PB Tregs when given intravenously (IV) and selectively targets tumor cells that overexpress IL-2R. Breast tumors have been shown to overexpress IL-2R which is associated with their malignant potential. We hypothesized that ONTAK® could (1) have direct anti-tumor activity in breast cancers that overexpress IL-2R, and (2) deplete Tregs resulting in generation of functional immune effector cells and enhanced anti-tumor immunity. A phase I-II study was conducted to evaluate the safety of IV ONTAK® and assess its effect on Tregs and endogenous immunity in patients with advanced refractory breast cancer.Materials and Methods: 15 patients with progressive stage IV breast cancer following standard therapy were sequentially enrolled and received IV ONTAK® 18 mcg/kg/day on Days1-5 every 21 days for a total of 6 cycles and/or maximal tumor response. Toxicity was evaluated on Days 1 8, and 14 of each cycle per CTEP CTCAE v3.0. Tumor response was evaluated per RECIST at baseline, and after cycles 3 and 6. PB was collected at baseline and after cycles 2, 4, and 6 for evaluation of Tregs, sIL-2R, and endogenous tumor-antigen specific T cell immunity to HER-2/neu (HER2), CEA, and MAGE-3 via RT-PCR, LUMINEX and IFN-γ ELISPOT assay, respectively. Expression of IL-2R in patient paraffin embedded tumor samples was analyzed by IHC analysis.Results: 15 subjects have been enrolled and 14/15 have completed treatment; median age is 58 years (range, 32-69) and median salvage regimens is 3 (range, 2-8). 7/14 subjects had triple negative tumors. 7 subjects completed 1-2 and 7 completed 3-6 ONTAK® cycles, respectively. 4 subjects who completed 6 cycles of ONTAK® had SD or PR per RECIST. ONTAK®-related toxicities have been primarily grade I and II fatigue, nausea, and headache; and transient grade 3 hypoalbuminemia and lymphopenia. Preliminary data in 2 subjects shows enhanced tumor-antigen specific T cell immunity defined as mean tumor antigen-specific T cell precursors:PBMC to CEA (pre- ONTAK® 1:250,000; post- ONTAK® 1:15,000) and HER2 (pre- ONTAK® 1:63,000; post- ONTAK® 1:6,312). Immunologic analyses are ongoing and will be presented along with clinical data on all patients.Conclusions: ONTAK® is well-tolerated when used as a salvage regimen in heavily pretreated breast cancer patients. Additionally, ONTAK® treatment can enhance endogenous immunity to known breast cancer antigens and potentially lead to more effective eradication of tumor.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4130.

Phase II Study of a HER-2/Neu (HER2) Intracellular Domain (ICD) Vaccine Given Concurrently with Trastuzumab in Patients with Newly Diagnosed Advanced Stage Breast Cancer

HER2 is a tumor antigen in breast cancer and several trials have demonstrated that breast cancer patients can be immunized against this protein. We have developed HER2 peptide based vaccines that are aimed at eliciting CD4+ Th1 tumor antigen specific T cell responses. Th1 effectors provide immunologic memory, enhance cross priming which will allow the elaboration of tumor specific CD8+ T cells, and stimulate epitope spreading which we have shown to be a potential biomarker of clinical response. 52 patients will be enrolled with the primary objective to determine relapse free survival after active immunization. Eligible patients are newly diagnosed with Stage III (B or C) or Stage IV breast cancer and begin vaccination within 6 months of starting maintenance trastuzumab. This interim report will present data on the first 25 patients enrolled; 21 stage IV and 4 locally advanced patients. The vaccine is well tolerated with all adverse events (AE) being Grade I or 2. The most common AE is injection site reaction. Moreover, the combination of HER2 vaccination with trastuzumab did not result in additive cardiac toxicity in these patients. Immune responses were evaluated by IFN-gamma ELISPOT. To date, 88% of patients immunized developed significant immunity to the components of the ICD vaccine. The majority, 75%, developed robust immunity to the HER2 protein. Our group has recently demonstrated that a broadening of immunity throughout the HER2 protein, to components of the protein that weren't in the vaccine, i.e. epitope spreading, may be associated with improved survival in vaccinated patients. 63% of immunized patients demonstrated evidence of intramolecular epitope spreading. We questioned whether such high frequencies of homing Type 1 T cells might modulate the immunosuppressive tumor microenvironment, so we evaluated whether circulating serum immunosuppressive cytokines were impacted by immunization. TGF-beta is an immunosuppressive cytokine secreted by tumor stroma and regulatory T cells. We found that the levels of serum TGF-beta decreased significantly in the majority of patients after vaccination. We further analyzed the correlation between the change of serum levels of TGF-beta post vaccination and HER2 ICD vaccine-induced T cell responses. We found that the greater the magnitude of the HER2 specific T cell response, as demonstrated by IFN-gamma secretion, the greater the decrease in serum TGF-beta (p=0.0045, r=0.742). The correlation between the increased epitope spreading T cell response and decreased levels of TGF-beta was even more significant (p=0.0003). The median overall survival has not been reached with 100% of patients alive at this time. Relapse free survival data will be presented.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5102.

The Impact of National Press Coverage on Early Phase Clinical Trial Recruitment and Enrollment

The American Society of Clinical Oncologists reports that only 5% of cancer patients ultimately enroll in a clinical trial. According to the National Cancer Institute, one key barrier to participation is a lack of knowledge about clinical trials, both on behalf of oncologists and the patients themselves. Unfortunately, many investigator-initiated and academic clinical trials simply do not have budgets that permit implementation of large-scale recruitment efforts. Recent experience by our group demonstrates that press coverage by national media is a particularly effective tool for generating public interest in clinical research, as well as increasing trial enrollment.In the third quarter of 2008, our academic translational research group was featured on a national news program. In the week following the broadcast, our group's website, which had been listed in the broadcast and accompanying web story, received an unprecedented number of hits. Not only did the broadcast generate interest in our group's research; more specifically, it translated to substantial increases in potential clinical trial candidates, and subsequently, increased trial enrollment. In the month following the broadcast, our group received 125 new clinical trial inquiries as a result of the feature. That number represented a seven-fold increase in new inquiries during the same period in 2007. Of those 125 contacts, more than half of patients were potentially eligible for one of our clinical trials based on an initial screening. From November 2008 to the present, nearly one-third of all clinical trial enrollments can be attributed to the news story. Enrollment to the vaccine trial specifically described in the news feature increased four fold in comparison to the same 6-month period in 2008-2009, with half of all new enrollments attributable to the news feature.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6078.

Preventing the Development of Breast Cancer by Immunizing with Multi-Antigen Vaccines Targeting Proteins Associated with Oncogenesis

Vaccines have been extremely successful in the prevention of infectious diseases. Although cancer vaccines have long been studied for the treatment of cancer, they have not been exploited as chemoprevention agents except in virally mediated malignancies. Human breast cancer is immunogenic and a variety of proteins involved in the malignant transformation or maintenance of the malignant phenotype have been identified as tumor antigens. Transgenic animal models are uniquely suited for evaluating the potential efficacy of preventative cancer vaccines. TgMMTV-neu mice, for example, develop neu-mediated breast cancer at about 150-200 days of life. Tumors are histologically similar to human breast cancer and have a molecular profile consistent with the luminal subtype. We have developed two multi-antigen vaccines targeting immunogenic proteins associated with oncogenesis and evaluated whether we could prevent the development of breast cancer in TgMMTV-neu mice. Each vaccine was composed of 3 different antigens. Class II epitopes derived from antigenic proteins involved in growth factor pathways comprised one vaccine and the other vaccine was plasmid DNA based and encoded immunogenic proteins involved in cell proliferation. The ability of active immunization to prevent breast cancer was evaluated in both older (18 week) and younger (5 week) mice. Vaccines were administered intradermally every two weeks for 3 immunizations and then monthly until the development of disease or 1 year had passed. Both vaccines prevented breast cancer development in older animals. 40% of peptide immunized older mice were cancer free at 1 year compared to 5% of controls (p=0.02). The DNA vaccine appeared to be even more effective in older animals with 60% of vaccinated mice tumor free as compared to 20% of controls (p=0.01). Protection from the development of cancer was mediated by T cells as evidenced by adoptive transfer of CD3+ cells purified from vaccinated and protected mice, sham immunized mice, and naïve mice. T cells from protected mice resulted in significant inhibition of tumor growth after a syngeneic tumor challenge (p=0.01 protected vs. sham vaccine). The cancer protective effect of immunization was more pronounced when vaccines were administered to the younger mice. The Class II epitope vaccine prevented cancer development in 65% of mice as compared to 5% of controls. The plasmid based vaccine protected 70% of mice from breast cancer. Active immunization was associated with a survival benefit in all groups. These data suggest breast cancer vaccines targeting biologically relevant proteins may be an effective approach to the prevention of breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1045.

Association of the level of HER2/neu (HER2) gene amplification in breast cancer and the magnitude of antigen specific T-cell immunity achieved after HER2 vaccination

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Background: Studies have demonstrated that the level of HER2 gene amplification in breast cancer, assessed by fluorescence in situ hybridization (FISH), correlates with favorable clinical response after treatment with trastuzumab. We questioned whether HER2 gene amplification impacted the development of HER2-specific T-cell immunity following immunization with a HER2 vaccine. Methods: Patients with HER2+ stage III or IV breast cancer, treated to complete remission or stable bone only disease, were enrolled in one of two concurrent clinical trials of HER2-specific vaccines. Eligibility criteria between the two studies were similar. Patients received either a plasmid DNA-based vaccine encoding the HER2 intracellular domain or a peptide-based vaccine composed of 3 HER2 class II epitopes. Peripheral blood was assessed for HER2-specific T-cell responses by interferon gamma (IFN-g) ELISPOT prior to, immediately after, and 6 months to 1 year after the end of vaccinations. Both immune response and FISH data were available on 31 patients. Results: Correlation of FISH levels to IFN-g spots/well in evaluable patients revealed the level of HER2 gene amplification was not related to the presence of pre-existent HER2-specific T-cell immunity prior to vaccination (p=0.43), the generation of a HER2-specific immune response after vaccination (p=0.35), or the persistence of the HER2-specific T-cell response (p=0.33). However, the magnitude of the T-cell response achieved was less as HER2 gene amplification increased (p=0.05). Conclusions: The level of HER2 gene amplification in the primary tumor can adversely impact the magnitude of HER2-specific T-cell immunity achieved after vaccination.

No significant financial relationships to disclose.