Abstract 700: Induction of cancer-specific T-cell responses in patients immunized with P10s-PADRE vaccine

Introduction: HR+/HER2− breast cancer is the most common form of breast cancer in the United States. HR+/HER2− tumors are known for a low number of tumor-infiltrating lymphocytes (TILs) and considered less immunogenic than other breast cancer subtypes. We have demonstrated that vaccination with P10s-PADRE, a carbohydrate-mimetic-based peptide, cancer vaccine in combination with standard-of-care chemotherapy in HR+/HER2− breast cancer patients led to an increase in TILs and stromal CD3+ T cells. The current study was performed to determine the vaccine specificity and anti-tumor functionality of T cells in treated patients.

Methods: Peripheral blood mononuclear cells (PBMCs) collected at the baseline and after vaccination were used in T-cell assays by multi-color ELISpot, examining Th1, Th2, and cytotoxic responses. PBMCs were also interrogated for the vaccine-induced changes in immune gene expression by next-generation RNA-seq analysis.

Results: We observed a significant increase in IFN-g, but not in IL-5 or IL-10, responses in post-immune PBMCs after stimulation with P10s, P10s-PADRE and polyclonal stimulation of T cells by anti-CD3/CD28 antibodies. Stimulation with cancer cell lysate resulted in a strikingly high IFN-g response in post-immune samples. Determining the trio of IFN-g, GzB, and IL-2 together with CD4/CD8 cell proliferation assays of consequent post vaccination specimens established the dynamics of effector T-cell populations. RNA-seq data clearly distinguished post-treatment samples by the increase in immune cell activation, cytokine response, and antigen presentation.

Conclusions: The data indicate that immunization of HR+/HER2− breast cancer patients with P10s-PADRE in combination with chemotherapy leads to specific activation of T-cells that recognize breast cancer cells. Improving immunogenicity of such immunologically cold tumors could increase the effectiveness of standard therapeutic approaches.

Citation Format: John J. Lee, Bernice C. Nounamo, Fariba Jousheghany, Issam Makhoul, Eric R. Siegel, Thomas Kieber-Emmons, Behjatolah Monzavi-Karbassi. Induction of cancer-specific T-cell responses in patients immunized with P10s-PADRE vaccine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 700.

Abstract P2-14-15: Timing of the immunization defines immune signature of a peptide cancer vaccine combined with Neoadjuvant chemotherapy in HR+ breast cancer patients

Background: We have developed P10s-PADRE, a carbohydrate-mimetic-based peptide, cancer vaccine and demonstrated its safety and immunogenicity in a Phase I clinical trial performed in stage IV breast cancer patients. HR+/HER2- breast cancer is the most common form of breast cancer diagnosed in the United States. These patients face a persistent risk of distant recurrence long after completion of their treatment and new strategies to activate anti-tumor immune responses can improve outcomes of standard therapies. The current study was performed to examine the feasibility, safety and immunogenicity of adding P10s-PADRE to standard-of-care chemotherapy in HR+/HER2− early-stage breast cancer patients. Methods: Five combination schedules were designed based on the timing of immunizations relative to a standard-of-care neoadjuvant chemotherapy regimen. Induction of on-treatment antibody and cellular responses, including T-cells, natural killer (NK) cells, and cytokines was determined. Tumor-infiltrating lymphocytes were quantified in core and surgical biopsies. The data were used to define the treatment effect in general and the vaccine contribution in particular. Results: Combination of P10s-PADRE with chemotherapy was safe and immunogenic. Antibody response was superior in a particular combination schedule, called schedule C, where 3 weekly immunizations preceded the first dose of chemotherapy. We observed that the schedule C, relative to other schedules, displayed an increase in CD16 expression on NK cells, a drop in serum IFN-γ, and an increase in quantity of stromal TILs in residual tumors. Subjects demonstrated a significant reduction in the size of their primary tumor and three subjects achieved pCR. Conclusions: The timing of the immunization relative to the chemotherapy seems to define the type and strength of the immune responses elicited. A particular combination schedule, schedule C, appears promising and the results warrant the conduct of randomized phase II trials.

Citation Format: Issam Makhoul, Saddam M Ibrahim, Muhammad Abu-Rmaileh, Fariba Jousheghany, Eric Siegel, Lora J Rogers, John J Lee, Sergio Pina-Oviedo, Ginell R Post, Thaddeus Beck, Thomas Kieber-Emmons, Behjatolah Monzavi-Karbassi. Timing of the immunization defines immune signature of a peptide cancer vaccine combined with Neoadjuvant chemotherapy in HR+ breast cancer patients [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 P2-14-15.

Association of DNA-Methylation Profiles With Immune Responses Elicited in Breast Cancer Patients Immunized With a Carbohydrate-Mimicking Peptide: A Pilot Study

Immune response to a given antigen, particularly in cancer patients, is complex and is controlled by various genetic and environmental factors. Identifying biomarkers that can predict robust response to immunization is an urgent need in clinical cancer vaccine development. Given the involvement of DNA methylation in the development of lymphocytes, tumorigenicity and tumor progression, we aimed to analyze pre-vaccination DNA methylation profiles of peripheral blood mononuclear cells (PBMCs) from breast cancer subjects vaccinated with a novel peptide-based vaccine referred to as P10s-PADRE. This pilot study was performed to evaluate whether signatures of differentially methylated (DM) loci can be developed as potential predictive biomarkers for prescreening subjects with cancer who will most likely generate an immune response to the vaccine. Genomic DNA was isolated from PBMCs of eight vaccinated subjects, and their DNA methylation profiles were determined using Infinium^® MethylationEPIC BeadChip array from Illumina. A linear regression model was applied to identify loci that were differentially methylated with respect to anti-peptide antibody titers and with IFN-γ production. The data were summarized using unsupervised-learning methods: hierarchical clustering and principal-component analysis. Pathways and networks involved were predicted by Ingenuity Pathway Analysis. We observed that the profile of DM loci separated subjects in regards to the levels of immune responses. Canonical pathways and networks related to metabolic and immunological functions were found to be involved. The data suggest that it is feasible to correlate methylation signatures in pre-treatment PBMCs with immune responses post-treatment in cancer patients going through standard-of-care chemotherapy. Larger and prospective studies that focus on DM loci in PBMCs is warranted to develop pre-screening biomarkers before BC vaccination.

Clinical Trial Registration:www.ClinicalTrials.gov, Identifier: NCT02229084.

Carbohydrate (Chondroitin 4) Sulfotransferase-11-Mediated Induction of Epithelial-Mesenchymal Transition and Generation of Cancer Stem Cells

INTRODUCTION

We have previously shown that the expression of carbohydrate (chondroitin 4) sulfotransferase-11 (CHST11) is elevated in human breast cancer tissues, and that its expression in human breast cancer cell lines is associated with aggressive behavior of cells. The clinical significance of CHST11 expression is unknown, and its function in breast cancer cells is not fully understood.

OBJECTIVE

The current study was performed to define the clinical significance of this gene and address its biological function in promoting the aggressive behavior of breast cancer cells.

METHODS

Publicly available datasets were analyzed to determine the correlation of CHST11 expression with breast cancer survival. MCF-7 cells were transfected with the human CHST11 gene, and MCF-7-CHST11 cells with stable expression of the gene were established. Morphology and metastatic capacity of transfected cells were monitored in vitro. E-cadherin and β-catenin expression was compared by immunofluorescence. The expression of genes involved in epithelial-mesenchymal transition (EMT) and pluripotency was determined using real-time PCR. The Wnt inhibitor, Wnt-C59, was used to examine the involvement of Wnt in CHST11-mediated morphology.

RESULTS

The elevated expression of CHST11 in breast tumor specimens was significantly associated with poor survival among patients. MCF-7-CHST11 cells displayed morphological characteristics consistent with EMT, together with a significantly higher proliferation rate, enhanced migratory potential, and more robust anchorage-independent growth. MCF-7-CHST11 cells showed decreased expression of E-cadherin and increased accumulation of β-catenin, as assessed by immunofluorescence. Consistently, increased expression of CHST11 resulted in upregulation of key EMT and stem cell markers. Morphological transition in MCF-7-CHST11 cells was partially reversed by co-incubation with an inhibitor of the Wnt pathway.

CONCLUSIONS

Our findings support a role for CHST11 in induction of EMT and stem cell-like properties. Our data also associate the expression levels of CHST11 in breast tumor specimens with patients' survival. The results have a significant implication for CHST11 expression level as a novel molecular signature for predictive and prognostic purposes in breast cancer. Moreover, with a possible role in driving tumor cell aggressiveness, CHST11 expression might be further considered as a potential therapeutic target for breast cancer.

Carbamate derivatives of colchicine show potent activity towards primary acute lymphoblastic leukemia and primary breast cancer cells-in vitro and ex vivo study

Colchicine (COL) shows strong anticancer activity but due to its toxicity towards normal cells its wider application is limited. To address this issue, a library of 17 novel COL derivatives, namely N-carbamates of N-deacetyl-4-(bromo/chloro/iodo)thiocolchicine, has been tested against two types of primary cancer cells. These included acute lymphoblastic leukemia (ALL) and human breast cancer (BC) derived from two different tumor subtypes, ER+ invasive ductal carcinoma grade III (IDCG3) and metastatic carcinoma (MC). Four novel COL derivatives showed higher anti-proliferative activity than COL (IC₅₀  = 8.6 nM) towards primary ALL cells in cell viability assays (IC₅₀ range of 1.1-6.4 nM), and several were more potent towards primary IDCG3 (IC₅₀ range of 0.1 to 10.3 nM) or MC (IC₅₀ range of 2.3-9.1 nM) compared to COL (IC₅₀ of 11.1 and 11.7 nM, respectively). In addition, several derivatives were selectively active toward primary breast cancer cells compared to normal breast epithelial cells. The most promising derivatives were subsequently tested against the NCI panel of 60 human cancer cell lines and seven derivatives were more potent than COL against leukemia, non-small-cell lung, colon, CNS and prostate cancers. Finally, COL and two of the most active derivatives were shown to be effective in killing BC cells when tested ex vivo using fresh human breast tumor explants. The present findings indicate that the select COL derivatives constitute promising lead compounds targeting specific types of cancer.

The response of phyllodes tumor of the breast to anticancer therapy: An in vitro and ex vivo study

Phyllodes tumors of the breast (PTB) are uncommon stromal-epithelial neoplasms, with the main recommended treatment being surgical removal. However, even with adequate resection, the risk of recurrence in the malignant form remains as high as 40%, and there is no recognized consensus on the most effective drugs for PTB. In the present study, an ex vivo model of malignant phyllodes and derived primary cell cultures were used to evaluate the effectiveness of a panel of different drugs, including the Bcl-2/Bcl-xL inhibitor ABT-263, salinomycin (SAL), doxorubicin (DOX), paclitaxel (TAX), vincristine (VCR), colchicine (COL) and cisplatin (CIS). ABT-263, SAL and DOX were highly effective towards phyllodes spindle cells when assessed in the ex vivo model, contributing to ~98% tumor cell death. Furthermore, ABT-263 was highly selective for tumor cells in this system, and exhibited little toxic effect on adjacent normal epithelial cells. Furthermore, consistent with findings in the ex vivo model, ABT-263 was significantly less toxic towards MCF 10A non-tumorigenic breast epithelial cells compared with SAL and DOX. A conditional reprogramming strategy was subsequently used, involving Rho kinase inhibition, to successfully generate primary phyllodes tumor cells that could be cultured for several passages. The primary cells were sensitive to DOX with an IC₅₀ of 0.40±0.07 µM in a standard viability assay and the preliminary results were obtained indicating sensitivity to ABT-263 and SAL. The present study demonstrated the feasibility of using explants and primary cells for drug discovery, selectively targeting PTB cells.

Abstract P6-10-06: Inducing immune responses to tumor associated carbohydrate antigens by a carbohydrate mimetic peptide vaccine: Clinical experience in phase I and phase II trials

Active immunization of cancer patients to induce de novo functional anti-tumor immune responses is an alternative/complementary approach to chemotherapy. Tumor vaccines hold the potential to deliver durable, specific and systemic anti-tumor responses in patients. We have been developing active vaccination strategies targeting tumor associated carbohydrate antigens (TACAs) using carbohydrate mimetic peptides. TACAs play roles in initiation and metastasis of cancer and considered as common targets shared by many tumor types. TACA support cell survival that can be interrupted by anti-carbohydrate antibodies. An early-phase 3+3 clinical trial was conducted to evaluate the feasibility, safety and immune functionality of a carbohydrate mimetic-peptide (CMP) vaccine referred to as P10s, which can induce TACA reactive, proapoptotic antibodies. In this trial a dose-escalation trial of vaccine plus adjuvant was conducted in two cohorts of 3 subjects each. Patients were restricted to females of all races with histologically or cytologically confirmed stage IV breast cancer who had stable disease and a positive recall-antigen response. P10s was synthesized with the Pan-T-cell epitope PADRE and formulated at 300 and 500 µg/injection with MONTANIDE™ ISA 51 VG for the 1st and 2nd cohorts, respectively. Doses of the appropriate formulation of the vaccine were administered to research participants subcutaneously on weeks 1, 2, 3, 7 and 19. Blood samples were collected at various time points and tested for presence and functionality of antibodies. Antibody response to P10s and in particular against the ganglioside GD2 was measured by ELISA. Binding of pre-immune and post-immune sera was assessed against breast cancer cell lines. Vaccination generates IgG response with serum antibodies capable of inhibiting tumor growth in spheroid culture of breast cancer cell lines. The vaccine induced antibodies in all 6 subjects, displaying significant cytotoxic activity against several representative human breast-cancer cell lines. Caspase 3 was involved in the postimmune serum-mediated apoptosis. No cytotoxicity toward a normal breast epithelial cell line was detected. Apoptosis and caspase 3 activation seems to be involved in anti-tumor cell activity. Immunization with the P10s vaccine was found to be safe and tolerable, and induces functional antibodies that potentially have a cell-death-mediated therapeutic benefit. Incubation of spheroids with post-immune serum further sensitized cells to drugs, improving the efficacy of drug treatment at lower doses. The data suggest that the vaccine-induced anti-tumor immune response in combination with standard of care chemotherapy may further improve clinical outcome. Consequently, we are testing the vaccine in a Phase II study in the neoadjuvant setting. 5 Cohorts of 5 patients each administered with the vaccine at different schedules of chemotherapy are being assessed for immune response to the vaccine as in the Phase I study and if the combination approach contributes to a difference in pathological complete response (PCR) from chemotherapy alone.

Citation Format: Kieber-Emmons T, Hutchins LF, Emanuel PD, Pennisi A, Siegel E, Jousheghany F, Karbassi BM, Makhoul I. Inducing immune responses to tumor associated carbohydrate antigens by a carbohydrate mimetic peptide vaccine: Clinical experience in phase I and phase II trials [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-10-06.

Tumor-associated Glycans and Tregs in Immunogenicity of an Autologous Cell-based Vaccine

Development of cancer vaccines targeting tumor-associated antigens (TAAs) is an alternative approach to chemotherapy with sustained anti-tumor effects. The success of active immunotherapy has been hampered by tumor-induced immune suppressors. Regulatory T cells (Tregs) are a population of immune suppressors with a proven role in regulating anti-tumor immune responses. Removing or subduing Tregs activity leads to more robust anti-tumor immune responses. Here, we used a cell-based vaccination strategy in the 4T1 murine mammary model to examine whether bulk removal of certain TAAs, using their glycan profile, can affect the immunogenicity of the vaccine. We employed affinity columns of several lectins that are reactive with breast cancer cell lines to deplete lectin-reactive TAAs, while enriching for other antigens. Wheat germ agglutinin (WGA), concanavalin A (Con A), Vicia villosa (VVA), and Griffonia simplicifolia lectin-I (GS-I) were used to fraction crude tumor secreted antigens (TSA). Fractions were tested for their ability to stimulate Tregs and their anti-tumor efficacy. We observed that crude TSA activated Tregs and activation of CD4⁺CD25⁺ cells led to an inhibitory function on CD4⁺CD25^- effector cells. Immunization of mice with GS-I- and VVA-depleted fractions significantly delayed tumor establishment and inhibited lung metastases. Depletion of WGA-reactive glycoconjugates led to activation of Tregs, larger tumors and more distant metastases. The data indicate that TAAs can be enriched using their glycan expression pattern to weaken immune suppression and improve anti-tumor response. Therefore, the efficacy of autologous cancer cell vaccination can be improved through enrichment for certain TAAs using carbohydrate specificity.

Relationship between level of HbA1C and breast cancer

Background

Diabetes and cancer are public health issues worldwide; studies have shown that diabetes is related to increased breast cancer mortality. The purpose of this study was to examine associations between HbA1C and obesity with tumor stage and mortality among breast cancer patients.

Methods

Data for 82 patients with breast cancer (36–89 years of age, diagnosed /treated 1999–2009) were provided by the University of Arkansas for Medical Sciences (UAMS) Data Trust Warehouse. Survival time was estimated from start date of service to date of last follow-up or date of death. The Kaplan–Meier method provided analysis of survival curves for two groups of HbA1C (HbA1C < 6.5% vs HbA1C ≥ 6.5%) and two groups of BMI (BMI < 30 vs BMI ≥ 30 kg/m2); survival curves were compared using log-rank tests. Associations between HbA1C and BMI, and between HbA1C and tumor stage were determined by chi-square.

Results

The relationship between tumor stages and HbA1C was not statistically significant (X² = 0.093, p = 0.47, df = 1). The relationship between obesity and HbA1C was statistically significant (X² = 6.13, p = 0.013, df = 1). Log-rank tests did not show statistically significant differences between survival curves (HbA1C curves, p = 0.4; Obesity curves, p = 0.09).

Conclusion

While there was a statistically significant association between HbA1C and obesity, there were no significant associations found with this analysis. However, there are clinically meaningful relationships based on observed trends. Future directions for research may involve exploring a larger sample of patients and the role of therapeutic regimens on blood sugar control and BMI of breast cancer patients and influence on cancer prognosis.

Pre-diagnosis blood glucose and prognosis in women with breast cancer

Background

The effect of moderately elevated blood glucose levels among non-diabetic subjects on cancer prognosis is not well described. The goal of this study was to examine the association of elevated random blood glucose (RBG) levels in non-diabetic breast cancer patients with overall survival (OS) and time to tumor recurrence (TTR).

Results

Forty-nine deaths and 32 recurrences occurred among 148 eligible study subjects during 855.44 person-years of follow-up, with median follow-up of 5.97 years. We observed that patients with elevated RBG levels experienced significantly shorter OS (hazard ratio [HR], 3.01; 95 % confidence interval [CI] (1.70–5.33); P < 0.001) and shorter TTR (HR, 2.08; CI (1.04–4.16); P = 0.04) as compared to patients with non-elevated RBG levels. After controlling for tumor grade, tumor stage, race, and BMI, elevated RBG continued to display high and statistically significant association with shorter OS (HR, 3.50; CI (1.87–6.54); P < 0.001). Adjustment for age, race, and BMI strengthened HR of RBG for TTR. The association of RGB with TTR lost its borderline statistical significance upon controlling for both tumor grade and stage.

Conclusions

The data suggest that elevated blood glucose is associated with poor prognosis of breast cancer patients. Given the potential clinical implication, these findings warrant further investigation.

CHST11 gene expression and DNA methylation in breast cancer

Our previously published data link P-selectin-reactive chondroitin sulfate structures on the surface of breast cancer cells to metastatic behavior of cells. We have shown that a particular sulfation pattern mediated by the expression of carbohydrate (chondroitin 4) sulfotransferase-11 (CHST11) correlates with P-selectin binding and aggressiveness of human breast cancer cell lines. The present study was performed to evaluate the prognostic value of CHST11 expression and determine whether aberrant DNA methylation controls CHST11 expression in breast cancer. Publicly available datasets were used to examine the association of CHST11 expression to aggressiveness and progression of breast cancer. Methylation status was analyzed using bisulfite genomic sequencing. 5-aza-2′-deoxycytidine (5AzadC) was used for DNA demethylation. Reduced representation bisulfite sequencing was performed in the CpG island of CHST11 with a minimum coverage of 10. Quantitative real-time RT-PCR was employed to confirm the expression profile of CHST11 in breast cancer cell lines. Flow cytometry was also used to confirm the expression of the CHST11 product, chondroitin sulfate A (CS-A). The expression of CHST11 was significantly higher in basal-like and Her2-amplified cell lines compared to luminal cell lines. CHST11 was also highly expressed in cancer tissues compared to normal tissues and the expression levels were significantly associated with tumor progression. We observed very low levels of DNA methylation in a CpG island of CHST11 in basal-like cells but very high levels in the same region in luminal cells. Treatment of MCF7 cells, a luminal cell line with very low expression of CHST11, with 5AzadC increased the expression of CHST11 and its immediate product, CS-A, in a dose-dependent manner. These results suggest that CHST11 may play a direct role in progression of breast cancer and that its expression is controlled by DNA methylation. Therefore, in addition to CHST11 mRNA levels, the methylation status of this gene also has potential as a prognostic biomarker.

Moving a Carbohydrate Mimetic Peptide into the clinic

Tumor-Associated Carbohydrate Antigens (TACAs) are broad-spectrum targets for immunotherapy. Immunization with Carbohydrate Mimetic Peptides (CMPs) is a strategy to induce broad-spectrum TACA-reactive antibodies hypothesized to interfere with cellular pathways involved in tumor cell survival. A Phase I study was conducted with a first-in-man CMP referred to as P10s, conjugated to the Pan T cell carrier PADRE, along with MONTANIDE(™) ISA 51 VG as adjuvant over a course of 5 immunizations. While designed as a safety and tolerability study, the potential for therapeutic impact was observed in a subject with metastatic lesions as evaluated before and after vaccine treatment. The subject received Vinorelbine and Trastuzumab (VT) for two months prior to study eligibility. PET scans showed partial response in the lungs and complete resolution of a previously enlarged subpectoral lymph node. Immunization with P10s vaccine resulted in responses to P10s, with serum and plasma antibodies reactive with and cytotoxic to human breast cancer cells in vitro, including the Trastuzumab-resistant HCC1954 cell line. However, the patient developed cystic masses in the brain parenchyma with no apparent evidence of metastases. The subject was switched to Docetaxel, Pertuzumab and Trastuzumab a year later, and her last PET scan showed a complete response in the lungs and lymph nodes. Incubation of cancer cells with a combination of vaccine-induced serum and docetaxel suggests that the induced antibodies sensitize tumor cells for more efficient killing upon administration of docetaxel. The data suggest that P10s-PADRE induces anti-tumor antibody response that in combination with chemotherapy can affect metastatic lesions in breast cancer patients.

Abstract 2889: Human antibodies induced by vaccination with a carbohydrate mimetic-peptide vaccine show functional anti-tumor activity on human lung-cancer cells

Introduction: Lung cancer is the most common cancer worldwide, and the leading cancer killer in both men and women in the United States. The 5-year survival rate for lung cancer ranges from &lt;2% to about 70% depending on stage. Current treatment options including surgery, chemotherapy, and radiotherapy have limited efficacy, as over half of people with lung cancer die within a year of initial diagnosis. Tumor vaccines hold the potential to deliver durable, specific and systemic anti-tumor responses in lung-cancer patients diagnosed with advanced disease. Appearance of tumor-associated carbohydrate antigens (TACAs) is the hallmark of cancer initiation and metastasis in many cancer types, including lung cancer. We have developed active vaccination strategies that target TACAs using peptide mimetics, and successfully vaccinated stage IV breast-cancer patients. The purpose of the current study is to evaluate functionality of vaccine-induced antibodies against lung-cancer cells.

Procedure: Patients with stage IV breast cancer underwent vaccination with the carbohydrate mimicking peptide P10s synthesized with the Pan T-cell peptide PADRE (P10s-PADRE). Doses of P10s-PADRE admixed with MONTANIDE™ ISA 51 VG were administered to subjects subcutaneously in rotating injection sites in the abdomen on weeks 1, 2, 3, 7 and 9. Pre-immune (week 1) and post-immune sera (weeks 4 and 7) were tested for functional activity against a non-Small Cell lung-cancer cell line (NCI-H522) and a Small Cell lung-cancer cell line (NCI-H69). Cell-surface carbohydrates were profiled and serum binding to cells was assayed by flow cytometry. Cytotoxicity, migration and invasion assays were performed to assess functional anti-lung cancer-cell activity of the sera.

Results: Both cell lines express relevant TACAs that can be targeted with P10s-PADRE immunization. Vaccinated serum reacted with tumor cells, induced toxicity, and prevented tumor-cell migration and invasion in vitro.

Conclusion: Our results show that P10s-PADRE vaccination of breast-cancer patients induces functional immune activity against lung-cancer cells. Accordingly, we propose to extend our successful vaccination strategy to lung-cancer patients with advanced stage III/IV disease. This group of patients has poor survival, and induction of functional antibodies can significantly increase disease control and survival rate.

Citation Format: Konstantinos Arnaoutakis, Fariba Jousheghany, Issam Makhoul, Laura Hutchins, Thomas Kieber-Emmons, Behjatolah Monzavi-Karbassi. Human antibodies induced by vaccination with a carbohydrate mimetic-peptide vaccine show functional anti-tumor activity on human lung-cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2889. doi:10.1158/1538-7445.AM2014-2889

Abstract 2704: Ectopic expression of CHST11 promotes proliferation and migration of human breast cancer cells

Introduction. We have previously demonstrated that the expression levels of carbohydrate (chondroitin 4) sulfotransferase-11 (CHST11) correlates with P-selectin binding and aggressiveness (basal-like, triple-negative and mesenchymal phenotype) of human breast cancer. The present study was performed to establish stably transfected cell lines and study the functional role of CHST11 in human breast cancer cells. Methods. MCF7 cells were transfected with a plasmid vector containing the CHST11 coding sequence. Stable transfectants, MCF-7-CHST11, were established. Flow cytometry and real-time PCR were used for expression analysis. Metastatic phenotype of cells was characterized through conduction of proliferation and migration assays. Morphology and growth pattern of MCF-7-CHST11 cells were monitored and compared to parental MCF-7 cells. Results. We observed that MCF-7-CHST11 reacted strongly with anti-chondroitin sulfate A (CS-A) antibody and recombinant P-selectin. CS-A is the immediate product of CHST11 activity. CHST11 expression significantly affected cell proliferation as MCF-7-CHST11 cells grew much faster. Migration assay using transwell chamber showed high migratory potential for MCF-7-CHST11 cells as compared to the parental MCF-7 cells. The significant migratory advantage was not proliferation dependent. The CHST11expression affected the morphology of cells and cell spreading behavior consistent with more efficient anchorage independent growth. Colony formation in soft agar, Invasion and adhesion assays are being performed at the present time. We are planning more experiments to study mechanisms involved. Conclusions. The data confirm that the CHST11 products on the cell surface can serve as P-selectin ligands. The results indicate that the CHST11 expression can affect metastatic phenotype of cancer cells by promoting cellular proliferation and migratory potential.

Citation Format: Alice Behrens, Fariba Jousheghany, Aiwei Yao-Borengasser, Thomas Kieber-Emmons, Behjatolah Monzavi-Karbassi. Ectopic expression of CHST11 promotes proliferation and migration of human breast cancer cells. [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 2704. doi:10.1158/1538-7445.AM2013-2704

Abstract 4018: DNA methylation controls CHST11 gene expression in breast cancer

Introduction: We have previously demonstrated that chondroitin sulfates (CS) play a crucial role in metastatic potential of breast cancer cells. We have shown that the expression level of carbohydrate (chondroitin 4) sulfotransferase-11 (CHST11) correlates with CS-A expression and aggressiveness of human breast cancer cells. The current study was mainly performed to determine whether the expression of CHST11 gene in breast cancer cells is controlled by DNA methylation. Methods: Quantitative real-time PCR was used to detect the expression of CHST11 in human breast cancer cell lines. MCF7 cells were treated with 5-aza-2′-deoxycytidine (5AzadC) for DNA demethylation and expression analysis. Methylation in MCF7, MDA-MB-231 cells and patient breast cancer specimens was analyzed using bisulfite genomic sequencing (BGS). Reduced representation bisulfite sequencing (RRBS) was performed in the CpG island of CHST11 with a minimum coverage of 10. Digital gene expression was used to estimate the number of transcribed copies of the CHST11 gene from the second-generation mRNA-sequencing data. Results: Treatment of MCF7 cells with 5-AzadC increased the expression of CHST11 and its product CS-A in a dose-dependent manner. We observed very low levels of DNA methylation in a CpG island of CHST11 in estrogen receptor-negative basal-like cell lines MDA-MB-231, MDA-MB-468, and BT-20, but very high levels in the same region in estrogen receptor-positive luminal MCF7, ZR-75-1, and T47-D cells. We found that the CpG island can also be hypomethylated in triple negative (negative for estrogen and progesterone receptors and Her2/neu) patient breast cancer tissues. Conclusions: The data suggest that DNA hypomethylation significantly contributes to CHST11 and surface CS-A expression in aggressive breast cancer cells. The data suggest that therapeutic use of DNA demethylating agents may promote more aggressive forms of breast cancer.

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 4018. doi:1538-7445.AM2012-4018

Carbohydrate mimetic peptides augment carbohydrate-reactive immune responses in the absence of immune pathology

Among the most challenging of clinical targets for cancer immunotherapy are Tumor Associated Carbohydrate Antigens (TACAs). To augment immune responses to TACA we are developing carbohydrate mimetic peptides (CMPs) that are sufficiently potent to activate broad-spectrum anti-tumor reactivity. However, the activation of immune responses against terminal mono- and disaccharide constituents of TACA raises concerns regarding the balance between “tumor destruction” and “tissue damage”, as mono- and disaccharides are also expressed on normal tissue. To support the development of CMPs for clinical trial testing, we demonstrate in preclinical safety assessment studies in mice that vaccination with CMPs can enhance responses to TACAs without mediating tissue damage to normal cells expressing TACA. BALB/c mice were immunized with CMPs that mimic TACAs reactive with Griffonia simplicifolia lectin 1 (GS-I), and tissue reactivity of serum antibodies were compared with the tissue staining profile of GS-I. Tissues from CMP immunized mice were analyzed using hematoxylin and eosin stain, and Luxol-fast blue staining for myelination. Western blots of membranes from murine mammary 4T1 cells, syngeneic with BALB/c mice, were also compared using GS-I, immunized serum antibodies, and naive serum antibodies. CMP immunization enhanced glycan reactivities with no evidence of pathological autoimmunity in any immunized mice demonstrating that tissue damage is not an inevitable consequence of TACA reactive responses.

Chondroitin sulfates play a major role in breast cancer metastasis: a role for CSPG4 and CHST11 gene expression in forming surface P-selectin ligands in aggressive breast cancer cells

Introduction

We have previously demonstrated that chondroitin sulfate glycosaminoglycans (CS-GAGs) on breast cancer cells function as P-selectin ligands. This study was performed to identify the carrier proteoglycan (PG) and the sulfotransferase gene involved in synthesis of the surface P-selectin-reactive CS-GAGs in human breast cancer cells with high metastatic capacity, as well as to determine a direct role for CS-GAGs in metastatic spread.

Methods

Quantitative real-time PCR (qRT-PCR) and flow cytometry assays were used to detect the expression of genes involved in the sulfation and presentation of chondroitin in several human breast cancer cell lines. Transient transfection of the human breast cancer cell line MDA-MB-231 with the siRNAs for carbohydrate (chondroitin 4) sulfotransferase-11 (CHST11) and chondroitin sulfate proteoglycan 4 (CSPG4 ) was used to investigate the involvement of these genes in expression of surface P-selectin ligands. The expression of CSPG4 and CHST11 in 15 primary invasive breast cancer clinical specimens was assessed by qRT-PCR. The role of CS-GAGs in metastasis was tested using the 4T1 murine mammary cell line (10 mice per group).

Results

The CHST11 gene was highly expressed in aggressive breast cancer cells but significantly less so in less aggressive breast cancer cell lines. A positive correlation was observed between the expression levels of CHST11 and P-selectin binding to cells (P < 0.0001). Blocking the expression of CHST11 with siRNA inhibited CS-A expression and P-selectin binding to MDA-MB-231 cells. The carrier proteoglycan CSPG4 was highly expressed on the aggressive breast cancer cell lines and contributed to the P-selectin binding and CS-A expression. In addition, CSPG4 and CHST11 were over-expressed in tumor-containing clinical tissue specimens compared with normal tissues. Enzymatic removal of tumor-cell surface CS-GAGs significantly inhibited lung colonization of the 4T1 murine mammary cell line (P = 0.0002).

Conclusions

Cell surface P-selectin binding depends on CHST11 gene expression. CSPG4 serves as a P-selectin ligand through its CS chain and participates in P-selectin binding to the highly metastatic breast cancer cells. Removal of CS-GAGs greatly reduces metastatic lung colonization by 4T1 cells. The data strongly indicate that CS-GAGs and their biosynthetic pathways are promising targets for the development of anti-metastatic therapies.

Fructose as a carbon source induces an aggressive phenotype in MDA-MB-468 breast tumor cells

Aberrant glycosylation is a universal feature of cancer cells, and certain glycan structures are well-known markers for tumor progression. Availability and composition of sugars in the microenvironment may affect cell glycosylation. Recent studies of human breast tumor cell lines indicate their ability to take up and utilize fructose. Here we tested the hypothesis that adding fructose to culture as a carbon source induces phenotypic changes in cultured human breast tumor cells that are associated with metastatic disease. MDA-MB-468 cells were adapted to culture media in which fructose was substituted for glucose. Changes in cell surface glycan structures, expression of genes related to glycan assembly, cytoskeleton F-actin, migration, adhesion and invasion were determined. Cells cultured in fructose expressed distinct cell-surface glycans. The addition of fructose affected sialylation and fucosylation patterns. Fructose feeding also increased binding of leukoagglutinating Phaseolus vulgaris isolectin, suggesting a possible rise in expression of branching beta-1, 6 GlcNAc structures. Rhodamine-phalloidin staining revealed an altered F-actin cytoskeletal system. Fructose accelerated cellular migration and increased invasion. These data suggest that changing the carbon source of the less aggressive MDA-MB-468 cell line induced characteristics associated with more aggressive phenotypes. These data could be of fundamental importance due to the markedly increased consumption of sweeteners containing free fructose in recent years, as they suggest that the presence of fructose in nutritional microenvironment of tumor cells may negatively affect the outcome for some breast cancer patients.

Preclinical studies of carbohydrate mimetic peptide vaccines for breast cancer and melanoma

Limited immune responses to tumor-associated carbohydrate antigens (TACA) are due in part to their being self-antigens. Immunization with xenoantigens of TACA provides an approach to break tolerance and augment responses to TACA. Carbohydrate mimetic peptides (CMPs) as xenoantigens can induce serum antibodies that target shared carbohydrate residues on differing carbohydrate structures. In preclinical studies, we observe that CMP immunization in mice induce immune responses that are effective in inhibiting the in vitro and in vivo growth of breast cancer and melanoma tumor cells expressing self-target antigens. CMPs of TACA can be further defined that induce IgM antibodies with broadened responses to both breast and melanoma cells. Consequently, CMPs are effective at generating a multifaceted carbohydrate-reactive immune response that should be clinically evaluated for their ability to amplify carbohydrate immune responses against circulating or disseminated tumor cells.

Chondroitin sulfate glycosaminoglycans as major P-selectin ligands on metastatic breast cancer cell lines

The metastatic breast cancer cell line, 4T1, abundantly expresses the oligosaccharide sialylated Lewis x (sLe(x)). SLe(x) oligosaccharide on tumor cells can be recognized by E- and P-selectin, contributing to tumor metastatic process. We observed that both selectins reacted with this cell line. However, contrary to the E-selectin reactivity, which was sLe(x) dependent, P-selectin reactivity with this cell line was sLe(x)-independent. The sLe(x)-Neg variant of the 4T1 cell line with markedly diminished expression of sLe(x) and lack of sLe(a), provided a unique opportunity to characterize P-selectin ligands and their contribution to metastasis in the absence of overlapping selectin ligands and E-selectin binding. We observed that P-selectin binding was Ca(2+)-independent and sulfation-dependent. We found that P-selectin reacted primarily with cell surface chondroitin sulfate (CS) proteoglycans, which were abundantly and stably expressed on the surface of the 4T1 cell line. P-selectin binding to the 4T1 cells was inhibited by heparin and CS glycosaminoglycans (GAGs). Moreover, Heparin administration significantly inhibited experimental lung metastasis. In addition, the data suggest that surface CS GAG chains were involved in P-selectin mediated adhesion of the 4T1 cells to murine platelets and human umbilical vein endothelial cells. The data suggest that CS GAGs are also the major P-selectin-reactive ligands on the surface of human MDA-MET cells. The results warrant conducting clinical studies on the involvement of cell surface CS chains in breast cancer metastasis and evaluation of various CS types and their biosynthetic pathways as target for development of treatment strategies for antimetastatic therapy of this disease.

Evaluating strategies to enhance the anti-tumor immune response to a carbohydrate mimetic peptide vaccine

Carbohydrate mimetic peptides of tumor associated carbohydrate antigens (TACA) are T-cell-dependent antigens and, therefore, immunization with these surrogates is predicted to overcome the low immunogenicity of carbohydrate antigens. Consistent with this hypothesis, we show that among the potential immune cells involved, peptide immunization led to an increase in T-cell populations. While peptide mimetics may also function as TLR binding ligands, we did not observe evidence of involvement of NK cells. Examining tumor challenged animals, we observed that peptide immunization and not tumor cells rendered IL-12 responsiveness to T-cells, as T-cells from peptide-immunized mice produced IFN-gamma upon stimulation with IL-12. Cyclophosphamide administration enhanced the anti-tumor efficacy of the vaccine, which was achieved by enhancing T-cell responses with no effect on NK cell population. Prophylactic immunization of mice with a DNA construct encoding carbohydrate mimetic peptides indicated a specific role for the mimotope vaccine in anti-tumor immune responses. These data suggest a role for both CD4(+) and CD8(+) T-cells induced by mimotopes of TACA in protective immunity against tumor cells.

Reduction of spontaneous metastases through induction of carbohydrate cross-reactive apoptotic antibodies

The selective targeting of tumor-associated carbohydrate Ags by the induction of serum Abs that trigger apoptosis of tumor cells as a means to reduce circulating tumor cells and micrometastases would be an advantage in cancer vaccine development. Some plant lectins like Griffonia simplicifolia lectin I and wheat germ agglutinin mediate the apoptosis of tumor cells. We investigated the possibility of using these lectins as templates to select peptide mimotopes of tumor-associated carbohydrate Ags as immunogens to generate cross-reactive Abs capable of mediating apoptosis of tumor cells. In this study, we show that immunization with a mimotope selected based on its reactivity with Griffonia simplicifolia lectin I and wheat germ agglutinin induced serum IgM Abs in mice that mediated the apoptosis of murine 4T1 and human MCF7 cell lines in vitro, paralleling the apoptotic activity of the lectins. Vaccine-induced anti-carbohydrate Abs reduced the outgrowth of micrometastases in the 4T1 spontaneous tumor model, significantly increasing survival time of tumor-bearing animals. This finding parallels suggestions that carbohydrate-reactive IgM with apoptotic activity may have merit in the adjuvant setting if the right carbohydrate-associated targets are identified.

1H-NMR metabolic markers of malignancy correlate with spontaneous metastases in a murine mammary tumor model

End-products of glycolysis as well as phospholipid precursors and catabolites have been suggested as metabolic indicators of tumor progression. To test the hypothesis that increased levels of such indicators can distinguish metastatic phenotypes, we determined a limited cellular 1H-NMR metabolic profile of subpopulations of murine mammary 4T1 cells that differ in their metastatic potential. Subpopulations with differing metastatic phenotypes were identified by sorting for the expression of the cell surface adhesion oligosaccharide sialylated Lewis x (sLeX). The sLeX-negative subpopulation metastasizes to the lung of syngeneic mice more rapidly than the sLeX-positive subpopulations. The metabolic profile of the sLeX-negative subpopulation indicated higher levels of lactate and total choline metabolites than the sLeX-positive subpopulation, suggesting that altered metabolism is a critical component of the malignant phenotype. Analysis of shed cellular material from the sLeX-negative subpopulation displayed an increased ratio of phosphocholine to glycerophosphocholine when compared to the parental line and sLeX-positive subpopulation. Serum obtained from mice inoculated with either sLeX-negative or sLeX-positive tumor cells contained broader methylene resonances (P = 0.0002; P = 0.0003) and narrower methyl resonances (P = 0.0013; P < 0.0001) when compared to serum of naive mice. However, line widths of methylene and methyl resonances were not useful for distinguishing between the two tumor phenotypes. Results of this study further support the notion that metabolic indicators of malignancy can correlate with in vivo metastatic behavior.

Deficiency in surface expression of E-selectin ligand promotes lung colonization in a mouse model of breast cancer

Expression of sialyl Lewis(x) (sLe(x)) and sLe(a) on tumor cells is thought to facilitate metastasis by promoting cell adhesion to selectins on vascular endothelial cells. Experiments supporting this concept usually bypass the early steps of the metastatic process by employing tumor cells that are injected directly into the blood. We investigated the relative role of sLe(x) oligosaccharide in the dissemination of breast carcinoma, employing a spontaneous murine metastasis model. An sLe(x) deficient subpopulation of the 4T1 mammary carcinoma cell line was produced by negative selection using the sLe(x)-reactive KM93 MAb. This subpopulation was negative for E-selectin binding but retained P-selectin binding. Both sLe(x)-negative and -positive cells grew at the same rate; however, sLe(x)-negative cells spread more efficiently on plates and had greater motility in wound-scratch assays. Mice inoculated in the mammary fat pad with sLe(x)-negative and -positive variants produced lung metastases. However, the number of lung metastases was significantly increased in the group inoculated with the sLe(x)-negative variant (p = 0.0031), indicating that negative selection for the sLe(x) epitope resulted in enrichment for a subpopulation of cells with a high metastatic phenotype. Cell variants demonstrated significant differences in cellular morphology and pattern of tumor growth in primary and secondary tumor sites. These results strongly suggest that loss of sLe(x) may facilitate the metastatic process by contributing to escape from the primary tumor mass.

A mimic of tumor rejection antigen-associated carbohydrates mediates an antitumor cellular response

Tumor-associated carbohydrate antigens are typically perceived as inadequate targets for generating tumor-specific cellular responses. Lectin profile reactivity and crystallographic studies demonstrate that MHC class I molecules can present to the immune system posttranslationally modified cytosolic peptides carrying O-beta-linked N-acetylglucosamine (GlcNAc). Here we report that a peptide surrogate of GlcNAc can facilitate an in vivo tumor-specific cellular response to established Meth A tumors that display native O-GlcNAc glycoproteins on the tumor cell surface. Peptide immunization of tumor-bearing mice had a moderate effect on tumor regression. Inclusion of interleukin 12 in the immunization regimen stimulated complete elimination of tumor cells in all of the mice tested, whereas interleukin 12 administration alone afforded no tumor growth inhibition. Adoptive transfer of immune T cells into tumor-bearing nude mice indicates a role for CD8+ T cells in tumor regression. This work postulates that peptide mimetics of glycosylated tumor rejection antigens might be further developed for immune therapy of cancer.

Fucosylated lactosamines participate in adhesion of HIV-1 envelope glycoprotein to dendritic cells

Carbohydrates expressed on HIV-1 gp160 are purported to bind to several receptor types that affect virus pathophysiology. Here, we define a potential role for fucosylated glycans involved in the adhesion of cells expressing anchored HIV-1 glycoprotein or HIV virions to human dendritic cells (DCs). We observe that a monoclonal antibody (FH6), with reactivity toward an extended dimeric form of a fucosyl lactosamine, binds to gp120 transfectants, blocking adhesion of these cells and virus particles to human DCs. We observe that serum antibodies induced by peptide mimetic of fucosylated carbohydrate core structures emulate the monoclonal antibody reactivity pattern, showing enhanced reactivity to HIV-1 envelope-expressing cell line and blocking the adhesion of these cells to human DCs. These results suggest a potential role for initial adherence of virally infected cells or virions mediated by fucosylated lactosamines expressed on the envelope protein. As these carbohydrates function as adhesion molecules associated with homing and dissemination processes, such interactions may contribute to the HIV infection process.

Strategies in cancer vaccines development

The recent definition of tumour-specific immunity in cancer patients and the identification of tumour-associated antigens have generated renewed enthusiasm for the application of immune-based therapies for the treatment of malignancies. Recent developments in cancer vaccines have also been based on an improved understanding of the cellular interactions required to induce a specific anti-tumour immune response. Consequently, a number of cancer vaccines have entered clinical trials. Targeting broad-spectrum tumour-associated antigens has emerged as a strategy to lower the risk of tumour escape due to the loss of specific nominal antigen. Amongst the most challenging of tumour-associated antigens to which to target in active specific immunotherapy applications are carbohydrate antigens. As carbohydrates are intrinsically T-cell-independent antigens, more novel approaches are perhaps needed to drive specific-T-cell-dependent immune responses to carbohydrate antigens. In this context peptide mimetics of core structures of tumour-associated carbohydrate antigens might be developed to augment immune responses to these broad-spectrum antigens.

Priming characteristics of peptide mimotopes of carbohydrate antigens

Immunization with peptide mimetics of carbohydrate antigens can induce functional carbohydrate-reactive antibodies. Here, we examine the immune characteristics of alternative approaches in prime and boost strategies using glycosylated HIV-1 envelope protein and model tumor associated carbohydrate antigens. Our results indicate that peptide mimotopes either in a DNA or carrier-conjugated format can induce comparable levels of IgM and IgG. Carbohydrate boosting of peptide-primed animals does not affect end-point titer, however, boosting mediates a stable long lasting carbohydrate reactive IgM response, not achievable by carbohydrate immunization alone. Boosting with carbohydrate in animals primed with DNA- or peptide-conjugate, facilitates the induction of detectable IgG with a dominant IgG2a isotype. Immunization with HIV-1 envelope glycoprotein of peptide-primed animals induces different IgG isotype profiles with a dominant IgG1 antibody. We observed that HIV-1 envelope glycoprotein immunization of peptide primed mice induces a cross-reactive cellular response, as detected by cytokine secretion, which lends to IFN-gamma production upon splenocyte stimulation and CTL activity against recombinant vaccinia virus infected cells after in vitro stimulation. DNA immunization with mimotope, inclusion of a T-cell epitope from the HIV-1 envelope protein in the expression cassette and co-administration with IL-12 or GM-CSF encoding plasmids activate a cellular response to the HIV-1 envelope protein.