Insulin-like growth factor-binding protein-2 is a target for the immunomodulation of breast cancer

Striking efficacy of a vaccine targeting TOP2A for triple-negative breast cancer immunoprevention

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that has a poor prognosis. TOP2A is a key enzyme in DNA replication and is a therapeutic target for breast and other cancers. TOP2A-specific Th1-promoting epitopes with optimal binding affinity to MHC II were identified using a combined scoring system. The multi-peptide TOP2A vaccine elicited a robust immunologic response in immunized mice, as demonstrated by the significant production of Th1 cytokines from immunized animals' splenocytes stimulated in vitro with TOP2A peptides. Anti-tumor efficacy of the TOP2A vaccine was demonstrated in a syngeneic TNBC mouse model, in which pre-graft preventive vaccination was associated with significantly decreased tumor growth as compared to adjuvant control. In a genetically engineered mouse (GEM) model of TNBC, vaccinated animals demonstrated a significant reduction in tumor incidence and average tumor volume compared to adjuvant control. Finally, we examined TCR sequences in CD4 tumor Infiltrating lymphocytes (TIL) from vaccinated mice and found that the TIL contained TCR sequences specific to the three vaccine peptides. These data indicate that our newly developed multi-peptide TOP2A vaccine is highly immunogenic, elicits TILs with vaccine specific TCRs, and is highly effective in preventing and intercepting TNBC development and progression in vivo.

Lynch syndrome cancer vaccines: A roadmap for the development of precision immunoprevention strategies

Hereditary cancer syndromes (HCS) account for 5~10% of all cancer diagnosis. Lynch syndrome (LS) is one of the most common HCS, caused by germline mutations in the DNA mismatch repair (MMR) genes. Even with prospective cancer surveillance, LS is associated with up to 50% lifetime risk of colorectal, endometrial, and other cancers. While significant progress has been made in the timely identification of germline pathogenic variant carriers and monitoring and early detection of precancerous lesions, cancer-risk reduction strategies are still centered around endoscopic or surgical removal of neoplastic lesions and susceptible organs. Safe and effective cancer prevention strategies are critically needed to improve the life quality and longevity of LS and other HCS carriers. The era of precision oncology driven by recent technological advances in tumor molecular profiling and a better understanding of genetic risk factors has transformed cancer prevention approaches for at-risk individuals, including LS carriers. MMR deficiency leads to the accumulation of insertion and deletion mutations in microsatellites (MS), which are particularly prone to DNA polymerase slippage during DNA replication. Mutations in coding MS give rise to frameshift peptides (FSP) that are recognized by the immune system as neoantigens. Due to clonal evolution, LS tumors share a set of recurrent and predictable FSP neoantigens in the same and in different LS patients. Cancer vaccines composed of commonly recurring FSP neoantigens selected through prediction algorithms have been clinically evaluated in LS carriers and proven safe and immunogenic. Preclinically analogous FSP vaccines have been shown to elicit FSP-directed immune responses and exert tumor-preventive efficacy in murine models of LS. While the immunopreventive efficacy of "off-the-shelf" vaccines consisting of commonly recurring FSP antigens is currently investigated in LS clinical trials, the feasibility and utility of personalized FSP vaccines with individual HLA-restricted epitopes are being explored for more precise targeting. Here, we discuss recent advances in precision cancer immunoprevention approaches, emerging enabling technologies, research gaps, and implementation barriers toward clinical translation of risk-tailored prevention strategies for LS carriers. We will also discuss the feasibility and practicality of next-generation cancer vaccines that are based on personalized immunogenic epitopes for precision cancer immunoprevention.

Spatial Transcriptomic Analysis of Ovarian Cancer Precursors Reveals Reactivation of IGFBP2 during Pathogenesis

Elucidating the earliest pathogenic steps in cancer development is fundamental to improving its early detection and prevention. Ovarian high-grade serous carcinoma (HGSC), a highly aggressive cancer, mostly originates from the fallopian tube epithelium through a precursor stage, serous tubal intraepithelial carcinoma (STIC). In this study, we performed spatial transcriptomic analysis to compare STICs, carcinoma, and their matched normal fallopian tube epithelium. Several differentially expressed genes in STICs and carcinomas were involved in cancer metabolism and detected in a larger independent transcriptomic dataset of ovarian HGSCs. Among these, insulin-like growth factor binding protein-2 (IGFBP2) was found to undergo DNA hypomethylation and to be increased at the protein level in STICs. Pyrosequencing revealed an association of IGFBP2 expression with the methylation state of its proximal enhancer, and 5-azacytidine treatment increased IGFBP2 expression. In postmenopausal fallopian tubes, where most STICs are detected, IGFBP2 immunoreactivity was detected in all 38 proliferatively active STICs but was undetectable in morphologically normal tubal epithelia, including those with TP53 mutations. In premenopausal fallopian tubes, IGFBP2 expression was limited to the secretory epithelium at the proliferative phase, and estradiol treatment increased IGFBP2 expression levels. IGFBP2 knockdown suppressed the growth of IGFBP2-expressing tubal epithelial cells via inactivation of the AKT pathway. Taken together, demethylation of the proximal enhancer of IGFBP2 drives tumor development by maintaining the increased IGFBP2 required for proliferation in an otherwise estrogen-deprived, proliferation-quiescent, and postmenopausal tubal microenvironment.

SIGNIFICANCE

Molecular studies of the earliest precursor lesions of ovarian cancer reveal a role of IGFBP2 in propelling tumor initiation, providing new insights into ovarian cancer development.

Targeting Glutamine Metabolism to Enhance Immunoprevention of EGFR-Driven Lung Cancer

Lung cancer is the leading cause of cancer death worldwide. Vaccination against EGFR can be one of the venues to prevent lung cancer. Blocking glutamine metabolism has been shown to improve anticancer immunity. Here, the authors report that JHU083, an orally active glutamine antagonist prodrug designed to be preferentially activated in the tumor microenvironment, has potent anticancer effects on EGFR-driven mouse lung tumorigenesis. Lung tumor development is significantly suppressed when treatment with JHU083 is combined with an EGFR peptide vaccine (EVax) than either single treatment. Flow cytometry and single-cell RNA sequencing of the lung tumors reveal that JHU083 increases CD8⁺ T cell and CD4⁺ Th1 cell infiltration, while EVax elicits robust Th1 cell-mediated immune responses and protects mice against EGFR^L858R mutation-driven lung tumorigenesis. JHU083 treatment decreases immune suppressive cells, including both monocytic- and granulocytic-myeloid-derived suppressor cells, regulatory T cells, and pro-tumor CD4⁺ Th17 cells in mouse models. Interestingly, Th1 cells are found to robustly upregulate oxidative metabolism and adopt a highly activated and memory-like phenotype upon glutamine inhibition. These results suggest that JHU083 is highly effective against EGFR-driven lung tumorigenesis and promotes an adaptive T cell-mediated tumor-specific immune response that enhances the efficacy of EVax.

Novel peptide-based vaccine targeting heat shock protein 90 induces effective antitumor immunity in a HER2+ breast cancer murine model

Background

Heat shock protein 90 (HSP90) is a protein chaperone for most of the important signal transduction pathways in human epidermal growth factor receptor 2-positive (HER2+) breast cancer, including human epidermal growth factor receptor 2, estrogen receptor, progesterone receptor and Akt. The aim of our study is to identify peptide-based vaccines and to develop an effective immunotherapeutics for the treatment of HER2+ breast cancer.

Methods

HSP90-derived major histocompatibility complex (MHC) class II epitopes were selected using in silico algorithms and validated by enzyme-linked immunospot (ELISPOT). In vivo antitumor efficacy was evaluated in MMTVneu-transgenic mice. HSP90 peptide-specific systemic T-cell responses were assessed using interferon gamma ELISPOT assay, and immune microenvironment in tumors was evaluated using multiplex immunohistochemistry and TCRβ sequencing.

Results

First, candidate HSP90-derived MHC class II epitopes with high binding affinities across multiple human HLA class II genotypes were identified using in silico algorithms. Among the top 10 peptides, p485 and p527 were selected as promising Th1 immunity-inducing epitopes with low potential for Th2 immunity induction. The selected MHC class II HSP90 peptides induced strong antigen-specific T cell responses, which was induced by cross-priming of CD8⁺ T cells in vivo. The HSP90 peptide vaccines were effective in the established tumor model, and their efficacy was further enhanced when combined with stimulator of interferon genes (STING) agonist and/or anticytotoxic T lymphocyte-associated antigen-4 antibody in MMTVneu-transgenic mice. Increased tumor rejection was associated with increased systemic HSP90-specific T-cell responses, increased T-cell recruitment in tumor microenvironment, intermolecular epitope spreading, and increased rearrangement of TCRβ by STING agonist.

Conclusions

In conclusion, we have provided the first preclinical evidence of the action mechanism of HSP90 peptide vaccines with a distinct potential for improving breast cancer treatment.

Reduced IGFBP-2 related immunoreactivity in human serum correlates with arterial stiffness in a healthy Chinese population

BACKGROUND

Circulating insulin-like growth factor binding protein 2 (IGFBP-2) is associated with metabolic changes in both physiological and pathological conditions. The aim of this study was to investigate the correlation between IGFBP-2 related immunoreactivity in serum and arterial stiffness in a healthy Chinese population.

METHODS

In this cross-sectional study, 360 healthy participants aged 37-87 years were recruited from 1500 and were divided into three groups according to serum IGFBP-2 related immunoreactivity (Tertile I, 25.437 ng/ml-120.870 ng/ml; Tertile II, 120.871 ng/ml-161.914 ng/ml; Tertile III, 161.915 ng/ml-321.636 ng/ml). Arterial stiffness was evaluated by measuring the brachial-ankle pulse wave velocity (baPWV), ankle-brachial index (ABI), and carotid intima-media thickness (cIMT). The association between IGFBP-2 related immunoreactivity and arterial stiffness was estimated by multiple stepwise regression.

RESULTS

Compared with the other two groups population, the individuals in Tertile I had significantly older age (62.66 ± 13.30 years, P < 0.01), lower level of triglyceride (1.08 ± 0.70 mmol/l, P < 0.01) and E/A (peak velocity of early filling and preak velocity of atrial filling ratio) (0.90 ± 0.33, P < 0.05). IGFBP-2 related immunoreactivity was inversely related with baPWV in the total population (r = -0.171, P < 0.01) and in Tertile I (r = -0.275, P < 0.01). After adjusting for age and the other confounders, no association was found between IGFBP-2 related immunoreactivity and baPWV in the total population. However, In Tertile I, reduced IGFBP-2 related immunoreactivity in serum was an independent risk factor of baPWV acceleration in three different adjustment models: Model 1 (no adjustment, P < 0.01), Model 2 (adjusted for age, P < 0.05), and Model 3 (adjusted for all variables, P < 0.05).

CONCLUSION

IGFBP-2 related immunoreactivity in serum is inversely associated with baPWV in a healthy Chinese population. This association did not change after adjustment for conventional risk factors for cardiovascular diseases in the subjects with the lowest IGFBP-2 related immunoreactivity. Consequently, reduction of IGFBP-2 related immunoreactivity may be a predictor of arterial stiffness. IGFBP-2 seems to be a potential intervention target in early atherosclerosis.

Anti-tumor activity of a T-helper 1 multiantigen vaccine in a murine model of prostate cancer

Prostate cancer is one of the few malignancies that includes vaccination as a treatment modality. Elements of an effective cancer vaccine should include the ability to elicit a Type I T-cell response and target multiple antigenic proteins expressed early in the disease. Using existing gene datasets encompassing normal prostate tissue and tumors with Gleason Score ≤ 6 and ≥ 8, 10 genes were identified that were upregulated and conserved in prostate cancer regardless of the aggressiveness of disease. These genes encoded proteins also expressed in prostatic intraepithelial neoplasia. Putative Class II epitopes derived from these proteins were predicted by a combination of algorithms and, using human peripheral blood, epitopes which selectively elicited IFN-γ or IL-10 dominant antigen specific cytokine secretion were determined. Th1 selective epitopes were identified for eight antigens. Epitopes from three antigens elicited Th1 dominant immunity in mice; PSMA, HPN, and AMACR. Each single antigen vaccine demonstrated significant anti-tumor activity inhibiting growth of implanted Myc-Cap cells after immunization as compared to control. Immunization with the combination of antigens, however, was superior to each alone in controlling tumor growth. When vaccination occurred simultaneously to tumor implant, multiantigen immunized mice had significantly smaller tumors than controls (p = 0.002) and a significantly improved overall survival (p = 0.0006). This multiantigen vaccine shows anti-tumor activity in a murine model of prostate cancer.

Breast cancer vaccines for treatment and prevention

Breast cancer is immunogenic and a variety of vaccines have been designed to boost immunity directed against the disease. The components of a breast cancer vaccine, the antigen, the delivery system, and the adjuvant, can have a significant impact on vaccine immunogenicity. There have been numerous immunogenic proteins identified in all subtypes of breast cancer. The majority of these antigens are weakly immunogenic nonmutated tumor-associated proteins. Mutated proteins and neoantigen epitopes are found only in a small minority of patients and are enriched in the triple negative subtype. Several vaccines have advanced to large randomized Phase II or Phase III clinical trials. None of these trials met their primary endpoint of either progression-free or overall survival. Despite these set-backs investigators have learned important lessons regarding the clinical application of breast cancer vaccines from the type of immune response needed for tumor eradication, Type I T-cell immunity, to the patient populations most likely to benefit from vaccination. Many therapeutic breast cancer vaccines are now being tested in combination with other forms of immune therapy or chemotherapy and radiation. Breast cancer vaccines as single agents are now studied in the context of the prevention of relapse or development of disease. Newer approaches are designing vaccines to prevent breast cancer by intercepting high-risk lesions such as ductal carcinoma in situ to limit the progression of these tumors to invasive cancer. There are also several efforts to develop vaccines for the primary prevention of breast cancer by targeting antigens expressed during breast cancer initiation.

Immunization with a Plasmid DNA Vaccine Encoding the N-Terminus of Insulin-like Growth Factor Binding Protein-2 in Advanced Ovarian Cancer Leads to High-level Type I Immune Responses

BACKGROUND

Cancer vaccines targeting nonmutated proteins elicit limited type I T-cell responses and can generate regulatory and type II T cells. Class II epitopes that selectively elicit type I or type II cytokines can be identified in nonmutated cancer-associated proteins. In mice, a T-helper I (Th1) selective insulin-like growth factor binding protein-2 (IGFBP-2) N-terminus vaccine generated high levels of IFNγ secreting T cells, no regulatory T cells, and significant antitumor activity. We conducted a phase I trial of T-helper 1 selective IGFBP-2 vaccination in patients with advanced ovarian cancer.

METHODS

Twenty-five patients were enrolled. The IGFBP-2 N-terminus plasmid-based vaccine was administered monthly for 3 months. Toxicity was graded by NCI criteria and antigen-specific T cells measured by IFNγ/IL10 ELISPOT. T-cell diversity and phenotype were assessed.

RESULTS

The vaccine was well tolerated, with 99% of adverse events graded 1 or 2, and generated high levels of IGFBP-2 IFNγ secreting T cells in 50% of patients. Both Tbet⁺ CD4 (P = 0.04) and CD8 (P = 0.007) T cells were significantly increased in immunized patients. There was no increase in GATA3⁺ CD4 or CD8, IGFBP-2 IL10 secreting T cells, or regulatory T cells. A significant increase in T-cell clonality occurred in immunized patients (P = 0.03, pre- vs. post-vaccine) and studies showed the majority of patients developed epitope spreading within IGFBP-2 and/or to other antigens. Vaccine nonresponders were more likely to have preexistent IGFBP-2 specific immunity and demonstrated defects in CD4 T cells, upregulation of PD-1, and downregulation of genes associated with T-cell activation, after immunization.

CONCLUSIONS

IGFBP-2 N-terminus Th1 selective vaccination safely induces type I T cells without evidence of regulatory responses.

Pulmonary Aerosol Delivery of Let-7b microRNA Confers a Striking Inhibitory Effect on Lung Carcinogenesis through Targeting the Tumor Immune Microenvironment

MicroRNAs are potential candidates for lung cancer prevention and therapy. A major limitation is the lack of an efficient delivery system to directly deliver miRNA to cancer cells while limiting systemic exposure. The delivery of miRNA via inhalation is a potential strategy for lung cancer prevention in high-risk individuals. In this study, the authors investigate the efficacy of aerosolized let-7b miRNA treatment in lung cancer prevention. Let-7b shows significant inhibition of B[a]P-induced lung adenoma with no detectable side effects. Single-cell RNA sequencing of tumor-infiltrating T cells from primary tumors reveals that Let-7b post-transcriptionally suppresses PD-L1 and PD-1 expression in the tumor microenvironment, suggesting that let-7b miRNAs may promote antitumor immunity in vivo. Let-7b treatment decreases the expression of PD-1 in CD8+ T cells and reduces PD-L1 expression in lung tumor cells. The results suggest that this aerosolized let-7b mimic is a promising approach for lung cancer prevention, and that the in vivo tumor inhibitory effects of let-7b are mediated, at least in part, by immune-promoting effects via downregulating PD-L1 in tumors and/or PD-1 on CD8+ T cells. These changes potentiate antitumor CD8+ T cell immune responses, and ultimately lead to tumor inhibition.

Multi-Epitope-Based Vaccines for Colon Cancer Treatment and Prevention

Background

Overexpression of nonmutated proteins involved in oncogenesis is a mechanism by which such proteins become immunogenic. We questioned whether overexpressed colorectal cancer associated proteins found at higher incidence and associated with poor prognosis could be effective vaccine antigens. We explored whether vaccines targeting these proteins could inhibit the development of intestinal tumors in the azoxymethane (AOM)-induced colon model and APC Min mice.

Methods

Humoral immunity was evaluated by ELISA. Web-based algorithms identified putative Class II binding epitopes of the antigens. Peptide and protein specific T-cells were identified from human peripheral blood mononuclear cells using IFN-gamma ELISPOT. Peptides highly homologous between mouse and man were formulated into vaccines and tested for immunogenicity in mice and in vivo tumor challenge. Mice treated with AOM and APC Min transgenic mice were vaccinated and monitored for tumors.

Results

Serum IgG for CDC25B, COX2, RCAS1, and FASCIN1 was significantly elevated in colorectal cancer patient sera compared to volunteers (CDC25B p=0.002, COX-2 p=0.001, FASCIN1 and RCAS1 p<0.0001). Epitopes predicted to bind to human class II MHC were identified for each protein and T-cells specific for both the peptides and corresponding recombinant protein were generated from human lymphocytes validating these proteins as human antigens. Some peptides were highly homologous between mouse and humans and after immunization, mice developed both peptide and protein specific IFN-γ-secreting cell responses to CDC25B, COX2 and RCAS1, but not FASCIN1. FVB/nJ mice immunized with CDC25B or COX2 peptides showed significant inhibition of growth of the syngeneic MC38 tumor compared to control (p<0.0001). RCAS1 peptide vaccination showed no anti-tumor effect. In the prophylactic setting, after immunization with CDC25B or COX2 peptides mice treated with AOM developed significantly fewer tumors as compared to controls (p<0.0002) with 50% of mice remaining tumor free in each antigen group. APC Min mice immunized with CDC25B or COX2 peptides developed fewer small bowel tumors as compared to controls (p=0.01 and p=0.02 respectively).

Conclusions

Immunization with CDC25B and COX2 epitopes consistently suppressed tumor development in each model evaluated. These data lay the foundation for the development of multi-antigen vaccines for the treatment and prevention of colorectal cancer.

Tumor-associated autoantibodies from mouse breast cancer models are found in serum of breast cancer patients

B cell responses to tumor antigens occur early in breast tumors and may identify immunogenic drivers of tumorigenesis. Sixty-two candidate antigens were identified prior to palpable tumor development in TgMMTV-neu and C3(1)Tag transgenic mouse mammary tumor models. Five antigens (VPS35, ARPC2, SERBP1, KRT8, and PDIA6) were selected because their decreased expression decreased survival in human HER2 positive and triple negative cell lines in a siRNA screen. Vaccination with antigen-specific epitopes, conserved between mouse and human, inhibited tumor growth in both transgenic mouse models. Increased IgG autoantibodies to the antigens were elevated in serum from women with ductal carcinoma in situ (DCIS) and invasive breast cancer (IBC). The autoantibodies differentiated women with DCIS from control with AUC 0.93 (95% CI 0.88-0.98, p < 0.0001). The tumor antigens identified early in the development of breast cancer in mouse mammary tumor models were conserved in human disease, and potentially identify early diagnostic markers in human breast tumors.

IGFBP2: integrative hub of developmental and oncogenic signaling network

Insulin-like growth factor (IGF) binding protein 2 (IGFBP2) was discovered and identified as an IGF system regulator, controlling the distribution, function, and activity of IGFs in the pericellular space. IGFBP2 is a developmentally regulated gene that is highly expressed in embryonic and fetal tissues and markedly decreases after birth. Studies over the last decades have shown that in solid tumors, IGFBP2 is upregulated and promotes several key oncogenic processes, such as epithelial-to-mesenchymal transition, cellular migration, invasion, angiogenesis, stemness, transcriptional activation, and epigenetic programming via signaling that is often independent of IGFs. Growing evidence indicates that aberrant expression of IGFBP2 in cancer acts as a hub of an oncogenic network, integrating multiple cancer signaling pathways and serving as a potential therapeutic target for cancer treatment.

IGFBP2 promotes immunosuppression associated with its mesenchymal induction and FcγRIIB phosphorylation in glioblastoma

Immunotherapy shows a promise for treating glioblastoma (GBM), the most malignant and immunosuppressive glioma. The mesenchymal phenotype of cancer cells was frequently reported to be associated with their induction of immunosuppression within the cancer microenvironment. Overexpressed insulin-like growth factor binding protein 2 (IGFBP2) promotes GBM cell migration and invasion, and contributes to glioma progression and cancer recurrence and poor survival in GBM. However, whether IGFBP2 can induce immunosuppression in GBM was not reported yet. Thus, the study applied a syngeneic mouse GBM model, human GBM samples, and cancer-immune cell co-culture experiments to investigate the effect of IGFBP2 on GBM exposed immune cells and its association with the mesenchymal induction. We found that IGFBP2 promoted the mesenchymal feature of GBM cells. The inhibition of IGFBP2 relieved immunosuppression by increasing CD8⁺ T and CD19⁺ B cells and decreasing CD163⁺ M2 macrophages. Further, the IGFBP2-promoted immunosuppression was associated with its induction of the mesenchymal feature of GBM cells and the inhibitory phosphorylated FcγRIIB of GBM exposed immune cells. Blocking IGFBP2 suppressed tumor growth and improved survival of tumor bearing mice in the mouse GBM model. These findings support the notion that targeting the IGFBP2 may present an effective immunotherapeutic strategy for mesenchymal GBMs.

The Effect of Mouse Strain, Sex, and Carcinogen Dose on Toxicity and the Development of Lung Dysplasia and Squamous Cell Carcinomas in Mice

In order to translate new treatments to the clinic, it is necessary to use animal models that closely recapitulate human disease. Lung cancer develops after extended exposure to carcinogens. It has one of the highest mutation rates of all cancer and is highly heterogenic. Topical treatment with N-nitrosotris-(2-chloroethyl)urea (NTCU) induces lung squamous cell carcinoma (SCC) with nonsynonymous mutation rates similar to those reported for human non-small cell lung cancer. However, NTCU induces lung cancer with variable efficacy and toxicity depending on the mouse strain. A detailed characterization of the NTCU model is needed. We have compared the effect of three different NTCU doses (20, 30, and 40 mmol/L) in female and male of NIH Swiss, Black Swiss, and FVB mice on tumor incidence, survival, and toxicity. The main findings in this study are (1) NIH Swiss mice present with a higher incidence of SCC and lower mortality compared with Black Swiss and FVB mice; (2) 30 mmol/L NTCU dose induces SCC at the same rate and incidence as the 40 mmol/L dose with lower mortality; (3) female mice present higher grade and incidence of preinvasive lesions and SCC compared with males; (4) NTCU-induced transformation is principally within the respiratory system; and (5) NTCU treatment does not affect the ability to elicit a specific adaptive immune response. This study provides a reference point for experimental designs to evaluate either preventive or therapeutic treatments for lung SCC, including immunotherapies, before initiating human clinical trials.

Tumor-associated antigens identified early in mouse mammary tumor development can be effective vaccine targets

Breast cancer vaccines composed of antigens identified by serological analysis of cDNA expression libraries (SEREX) induce antigen specific immune responses in patients but have had disappointing clinical benefits. While many attempts to modify the adjuvants and vaccine method have been tried, one issue not addressed was whether the SEREX tumor-associated antigens identified from late stages of disease were ideal targets. We questioned in the transgenic TgMMTV-neu mouse model whether the antigen repertoire is distinct between early and late stage breast cancer and whether the antigens identified via SEREX from transgenic mice with early or late stage tumors would elicit differential anti-tumor effects to address this question. Three early stage antigens, Pdhx, Stk39, and Otud6B, were identified from a SEREX screen of mice prior to development of palpable lesions. Formulated into a vaccine, each early antigen inhibited tumor growth (p < 0.0001). The antigens identified from mice with late stage tumors (Swap70, Gsn, and Arhgef2) were unable to inhibit tumor growth when used as vaccines (for example Gsn p = 0.26). Each of the three early stage antigens were essential for tumor survival in syngeneic mouse tumor cells and in human breast cancer cell lines across breast cancer subtypes. Silencing protein expression of the early antigens increased apoptosis (p < 0.0001 for all antigens in mouse and p < 0.05 for all antigens in human triple negative breast cancer) and decreased survival (p < 0.0001 for all antigens in mouse and human triple negative and HER2 positive breast cancer). Overexpression of the early stage antigens in women with breast cancer predicted worse prognosis (p = 0.03) while overexpression of late stage antigens did not impact prognosis (p = 0.09). These data suggest that antigens expressed earlier in breast tumor development and functionally relevant to breast tumor growth may be more effective targets for therapeutic breast cancer vaccines than antigens identified in later disease.

Proteomics biomarkers for solid tumors: Current status and future prospects

Cancer is a heterogeneous multifactorial disease, which continues to be one of the main causes of death worldwide. Despite the extensive efforts for establishing accurate diagnostic assays and efficient therapeutic schemes, disease prevalence is on the rise, in part, however, also due to improved early detection. For years, studies were focused on genomics and transcriptomics, aiming at the discovery of new tests with diagnostic or prognostic potential. However, cancer phenotypic characteristics seem most likely to be a direct reflection of changes in protein metabolism and function, which are also the targets of most drugs. Investigations at the protein level are therefore advantageous particularly in the case of in-depth characterization of tumor progression and invasiveness. Innovative high-throughput proteomic technologies are available to accurately evaluate cancer formation and progression and to investigate the functional role of key proteins in cancer. Employing these new highly sensitive proteomic technologies, cancer biomarkers may be detectable that contribute to diagnosis and guide curative treatment when still possible. In this review, the recent advances in proteomic biomarker research in cancer are outlined, with special emphasis placed on the identification of diagnostic and prognostic biomarkers for solid tumors. In view of the increasing number of screening programs and clinical trials investigating new treatment options, we discuss the molecular connections of the biomarkers as well as their potential as clinically useful tools for diagnosis, risk stratification and therapy monitoring of solid tumors.

Immune heterogeneity and clinicopathologic characterization of IGFBP2 in 2447 glioma samples

Glioblastoma is an immunosuppressive, deadly brain tumor. IGFBP2, a circulating biomarker for cancer diagnosis and a potential immunotherapeutic target, is attracting more and more attention from oncologists and clinicians. Thus, it is urgent to thoroughly investigate the immune biological process of IGFBP2 to understand tumor immune complexity and provide potential evidence for anti-IGFBP2 therapy. Through authoritative public databases, we enrolled a total of 2447 glioma samples with gene expression profiles. Then, the clinical characteristics and immunosuppressive status of IGFBP2 in the glioma samples were analyzed. Immunohistochemical staining detected the expression of immunosuppressive biomarkers. We found that IGFBP2 expression was upregulated in high-grade glioma and GBM and downregulated in IDH mutant glioma. Increased IGFBP2 accompanied PTEN loss and EGFR amplification. Bioinformatic analysis revealed that IGFBP2 is related to immunological processes. We further selected specific immunologic related gene sets and found IGFBP2 predominated immunosuppressive activities in GBM. Furthermore, we explored the relationship between IGFBP2 and genes that were well-characterized glioma-mediated immunosuppressive molecules to investigate the potential effect of IGFBP2. We discovered that IGFBP2 was correlated with CHI3L1, TNFRSF1A, LGALS1, TIMP1, VEGFA, ANXA1 and LGALS3, which were classic immunosuppressive biomarkers. Higher IGFBP2 expression predicted unfavorable survival for patients with GBM. Our findings implied that IGFBP2 is involved in immunosuppressive activities and is an independent unfavorable prognostic biomarker for patients with GBM. IGFBP2 is a potential immunotherapeutic target for GBM in future clinical trials.

Deregulation of IGF-binding proteins -2 and -5 contributes to the development of endocrine resistant breast cancer in vitro

Tamoxifen (TAM) remains the adjuvant therapy of choice for pre-menopausal women with ERα-positive breast cancer. Resistance and recurrence remain, however, a major challenge with many women relapsing and subsequently dying. The insulin-like growth factor (IGF) axis is involved in breast cancer pathogenesis and progression to endocrine resistant disease, but there is very little data on the expression and potential role of IGF-binding proteins (IGFBP) during acquisition of the resistant phenotype. The aim of this study was to determine the expression and functional role of IGFBP-2 and -5 in the development of TAM resistance (TamR) in vitro and to test retrospectively whether they were predictive of resistance in a tissue microarray of 77 women with primary breast cancers who relapsed on/after endocrine therapy and 193 who did not with long term follow up. Reciprocal expression of IGFBP-2 and IGFBP-5 was observed at both mRNA and protein level in TamR cells. IGFBP-2 expression was increased by 10-fold while IGFBP-5 was decreased by 100-fold, compared to TAM-sensitive control cells. shRNA-mediated silencing of IGFBP-2 in TamR cells restored TAM sensitivity suggesting a causal role for this gene in TamR. While silencing of IGFBP-5 in control cells had no effect on TAM sensitivity, it significantly increased the migratory capacity of these cells. Quantitative image analysis of immunohistochemical data failed, however, to demonstrate an effect of IGFBP2 expression in endocrine-relapsed patients. Likewise, IGFBP-2 and IGFBP-5 expression failed to show any significant associations with survival either in patients relapsing or those not relapsing on/after endocrine therapy. By contrast, in silico mining of a separate published dataset showed that in patients who received endocrine treatment, loss of expression of IGBP-5 was significantly associated with worse survival. Overall these data suggest that co-ordinated and reciprocal alteration in IGFBP-2 and −5 expression may play a role in the acquisition of endocrine resistance.

Immunoprevention of KRAS-driven lung adenocarcinoma by a multipeptide vaccine

Lung cancer remains the leading cause of cancer death worldwide. Mutations in KRAS are detected in up to 30% of lung cancer cases. No effective therapies specifically targeting mutant KRAS have been developed. Vaccination against KRAS mutants is one of the venues of active exploration. The present study evaluated both immunogenicity and antitumor efficacy of a newly formulated multipeptide vaccine targeting multiple epitopes of the KRAS molecule. The formulated vaccine contained top four peptides, which elicited the strongest immunologic response and showed 100% sequence homology between human and mouse. The multipeptide KRAS vaccine was tested in an inducible CCSP-TetO-KRAS^G12D mouse model, where the vaccine was administered prior to activating the mutant KRAS protein. The KRAS peptide vaccine exhibited striking efficacy, reducing tumor number and tumor burden by >80% when compared with adjuvant alone. Splenocytes collected from vaccinated animals showed a robust immunologic response to the immunizing peptides. Furthermore, in vitro stimulation of these splenocytes by the vaccinated peptides resulted in the secretion of cytokines indicative of Th1 responses but with minimal secretion of Th2-related cytokines. The multipeptide KRAS vaccine was immunogenic and efficacious in the primary prevention of KRAS-induced lung cancer, indicating that the approach potentially can be used to prevent other KRAS-driven cancers, either alone or in combination with other modalities.

Immunization against HIF-1α Inhibits the Growth of Basal Mammary Tumors and Targets Mammary Stem Cells In Vivo

Purpose: Triple-negative breast cancer (TNBC) represents a cancer stem cell-enriched phenotype. Hypoxia-inducible factor-1α (HIF-1α) induces the expression of proteins associated with stemness and is highly upregulated in TNBC. We questioned whether HIF-1α was immunogenic and whether vaccination targeting HIF-1α would impact the growth of basal-like mammary tumors in transgenic mice.Experimental Design: We evaluated HIF-1α-specific IgG in sera from controls and patients with breast cancer. Class II epitopes derived from the HIF-1α protein sequence were validated by ELISPOT. To assess therapeutic efficacy, we immunized Tg-MMTVneu and C3(1)Tag mice with HIF-1α Th1-inducing peptides. Stem cells were isolated via magnetic bead separation. Levels of HIF-1α and stem cells in the tumor were quantitated by Western blotting and flow cytometry.Results: The magnitude (P < 0.001) and incidence (P < 0.001) of HIF-1α-specific IgG were elevated in TNBC patients compared with controls. Both breast cancer patients and donors showed evidence of HIF-1α-specific Th1 and Th2 immunity. Three HIF-1α-specific Th1 class II restricted epitopes that were highly homologous between species elicited type I immunity in mice. After HIF-1α vaccination, mammary tumor growth was significantly inhibited in only C3(1)Tag (basal-like/stem cell^high; P < 0.001) not TgMMTV-neu (luminal/neu/stem cell^low; P = 0.859) murine models. Vaccination increased type I T cells in the tumor (P = 0.001) and decreased cells expressing the stem cell marker, Sca-1, compared with controls (P = 0.004).Conclusions: An HIF-1α vaccine may be uniquely effective in limiting tumor growth in TNBC. Inhibiting outgrowth of breast cancer stem cells via active immunization in the adjuvant setting may impact disease recurrence. Clin Cancer Res; 23(13); 3396-404. ©2016 AACR.

Selection of epitopes from self-antigens for eliciting Th2 or Th1 activity in the treatment of autoimmune disease or cancer

Vaccines have been valuable tools in the prevention of infectious diseases, and the rapid development of new vectors against constantly mutating foreign antigens in viruses such as influenza has become a regular, seasonal exercise. Harnessing the immune response against self-antigens is not necessarily analogous or as achievable by iterative processes, and since the desired outcome includes leaving the targeted organism intact, requires some precision engineering. In vaccine-based treatment of autoimmunity and cancer, the proper selection of antigens and generation of the desired antigen-specific therapeutic immunity has been challenging. Both cases involve a threshold of existing, undesired immunity that must be overcome, and despite considerable academic and industry efforts, this challenge has proven to be largely refractory to vaccine approaches leveraging enhanced vectors, adjuvants, and administration strategies. There are in silico approaches in development for predicting the immunogenicity of self-antigen epitopes, which are being validated slowly. One simple approach showing promise is the functional screening of self-antigen epitopes for selective Th1 antitumor immunogenicity, or inversely, selective Th2 immunogenicity for treatment of autoimmune inflammation. The approach reveals the importance of confirming both Th1 and Th2 components of a vaccine immunogen; the two can confound one another if not parsed but may be used individually to modulate antigen-specific inflammation in autoimmune disease or cancer.

Epidermal growth factor receptor derived peptide vaccination to prevent lung adenocarcinoma formation: An in vivo study in a murine model of EGFR mutant lung cancer

The ability to prevent disease is the holy grail of medicine. For decades, efforts have been made to extend the successes seen with vaccination against infectious diseases to cancer. In some instances, preventive vaccination against viruses (prototypically HPV) has successfully prevented tumorigenesis and will make a major impact on public health in the decades to come. However, the majority of cancers that arise are a result of genetic mutation within the host, or non-viral environmental exposures. We present compelling evidence that vaccination against an overexpressed self-tumor oncoprotein has the potential to prevent tumor development. Vaccination against the Epidermal Growth Factor Receptor (EGFR) using a multipeptide vaccine in a preventive setting decreased EGFR-driven lung carcinogenesis by 76.4% in a mouse model of EGFR-driven lung cancer. We also demonstrate that anti-EGFR vaccination primes the development of a robust immune response in vivo. This study provides proof of concept for the first time that targeting tumor drivers in a preventive setting in lung cancer using peptide vaccination can inhibit tumorigenesis and may provide useful clinical insights into the development of strategies to vaccinate against EGFR in populations where EGFR-mutant disease is highly prevalent. © 2015 Wiley Periodicals, Inc.

The Antitumor Efficacy of IL2/IL21-Cultured Polyfunctional Neu-Specific T Cells Is TNFα/IL17 Dependent

PURPOSE

Infusion of HER2-specific T cells, derived from vaccine-primed patients and expanded with IL2/IL12, has induced tumor regression in a minority of patients with metastatic treatment-refractory HER2(+) breast cancer. We questioned whether alteration of cytokine growth factors used to culture vaccine-primed T cells could improve antitumor activity.

EXPERIMENTAL DESIGN

Using the TgMMTV-neu murine mammary tumor model, we cultured T cells derived from mice immunized with a previously defined neu class II peptide, p98-114 (neu p98), and evaluated different cytokine combinations for expansion.

RESULTS

Infusion of neu p98-specific T-cell lines derived from all cytokine conditions evaluated resulted in significant antitumor activity compared with infused naïve splenocytes (P < 0.05). T cells cultured with IL2/IL21 could uniquely mediate complete regression of spontaneous mammary tumors. IL2/IL21 cultured neu-specific T cells demonstrated a different cytokine secretion pattern as compared with other cultured T cells; secreting high levels of TNFα and IL17 (P < 0.05). Moreover, tumor-infiltrating CD8(+) cells were significantly increased after the infusion of IL2/IL21 cultured T cells as compared with tumors treated with T cells expanded under other cytokine conditions (P < 0.001). The antitumor effect of the infusion of IL2/IL21 cultured cells was mediated by CD8 T cells. Depletion of TNFα or IL17, but not IFNγ, abrogated the tumor growth inhibition induced by the IL2/IL21 T cells and markedly decreased the influx of CD8 into tumors. Finally, IL2/IL21-cultured human antigen specific T cells also displayed a similar polyfunctional Th1/Th17 phenotype.

CONCLUSIONS

Expansion of HER2 vaccine-primed T cells with IL2/IL21 may have the potential to effectively mediate tumor regression when used in adoptive transfer. Clin Cancer Res; 22(9); 2207-16. ©2015 AACR.

Immunologic approaches to cancer prevention-current status, challenges, and future perspectives

The potential of the immune system to recognize and reject tumors has been investigated for more than a century. However, only recently impressive breakthroughs in cancer immunotherapy have been seen with the use of checkpoint inhibitors. The experience with various immune-based strategies in the treatment of late cancer highlighted the importance of negative impact advanced disease has on immunity. Consequently, use of immune modulation for cancer prevention rather than therapy has gained considerable attention, with many promising results seen already in preclinical and early clinical studies. Although not without challenges, these results provide much excitement and optimism that successful cancer immunoprevention could be within our reach. In this review we will discuss the current state of predominantly primary and secondary cancer immunoprevention, relevant research, potential barriers, and future directions.

Preservation of tumor-host immune interactions with luciferase-tagged imaging in a murine model of ovarian cancer

BACKGROUND

Ovarian cancer is immunogenic and residual tumor volume after surgery is known to be prognostic. Ovarian cancer often follows a recurring-remitting course and microscopic disease states may present ideal opportunities for immune therapies. We sought to establish the immune profile of a murine model of ovarian cancer that allows in vivo tumor imaging and the quantitation of microscopic disease.

RESULTS AND DISCUSSION

Baseline imaging and weight measurements were taken within 1 and 2 weeks after intraperitoneal tumor injection, respectively. Significantly higher photons per second from baseline imaging were first observed 5 weeks after tumor cell injection (p < 0.05) and continued to be significant through 8 weeks after injection (p < 0.01), whereas a significant increase in weight above baseline was not observed until day 56 (p < 0.0001). Expression of luc2 in ID8 cells did not alter the cellular immune microenvironment of the tumor. FOXP3+ T cells were more likely to be detected in the intraepithelial compartment and CD4+ T cells in the stroma as compared to CD3+ T cells, which were found equally in stroma and intraepithelial compartments.

CONCLUSIONS

Use of an intraperitoneal tumor expressing a codon-optimized firefly luciferase in an immunocompetent mouse model allows tumor quantitation in vivo and detection of microscopic tumor burdens. Expression of this foreign protein does not significantly effect tumor engraftment or the immune microenvironment of the ID8 cells in vivo and may allow novel immunotherapies to be assessed in a murine model for their translational potential to ovarian cancers in remission or minimal disease after primary cytoreductive surgery or chemotherapy.

METHODS

Mouse ovarian surface epithelial cells from C57BL6 mice transformed after serial passage in vitro were transduced with a lentiviral vector expressing a codon optimized firefly luciferase (luc2). Cell lines were selected and luc2 expression functionally confirmed in vitro. Cell lines were intraperitoneally (IP) implanted in albino C57BL/6/BrdCrHsd-Tyrc mice and albino B6(Cg)-Tyrc-2 J/J mice for serial imaging. D-luciferin substrate was injected IP and tumors were serially imaged in vivo using a Xenogen IVIS. Tumor take, weights, and luminescent intensities were measured. Immunohistochemistry was performed on tumors and assessed for immune infiltrates in stromal and intraepithelial compartments.

Novel anti IGFBP2 single chain variable fragment inhibits glioma cell migration and invasion

Insulin like growth factor binding protein 2 (IGFBP2) is highly up regulated in glioblastoma (GBM) tissues and has been one of the prognostic indicators. There are compelling evidences suggesting important roles for IGFBP2 in glioma cell proliferation, migration and invasion. Extracellular IGFBP2 through its carboxy terminal arginine glycine aspartate (RGD) motif can bind to cell surface α5β1 integrins and activate pathways downstream to integrin signaling. This IGFBP2 activated integrin signaling is known to play a crucial role in IGFBP2 mediated invasion of glioma cells. Hence a molecular inhibitor of carboxy terminal domain of IGFBP2 which can inhibit IGFBP2-cell surface interaction is of great therapeutic importance. In an attempt to develop molecular inhibitors of IGFBP2, we screened single chain variable fragment (scFv) phage display libraries, Tomlinson I (Library size 1.47 × 10(8)) and Tomlinson J (Library size 1.37 × 10(8)) using human recombinant IGFBP2. After screening we obtained three IGFBP2 specific binders out of which one scFv B7J showed better binding to IGFBP2 at its carboxy terminal domain, blocked IGFBP2-cell surface association, reduced activity of matrix metalloprotease 2 in the conditioned medium of glioma cells and inhibited IGFBP2 induced migration and invasion of glioma cells. We demonstrate for the first time that in vitro inhibition of extracellular IGFBP2 activity by using human scFv results in significant reduction of glioma cell migration and invasion. Therefore, the inhibition of IGFBP2 can serve as a potential therapeutic strategy in the management of GBM.

IGFBP-2 and -5: important regulators of normal and neoplastic mammary gland physiology

The insulin-like growth factor (IGF) axis plays an important role in mammary gland physiology. In addition, dysregulation of this molecular axis may have a causal role in the aetiology and development of breast cancer (BC). This report discusses the IGF axis in normal and neoplastic mammary gland with special reference to IGF binding proteins (IGFBPs) -2 and -5. We describe how these high affinity binders of IGF-1 and IGF-2 may regulate local actions of growth factors in an autocrine and/or paracrine manner and how they also have IGF-independent effects in mammary gland. We discuss clinical studies which investigate both the prognostic value of IGFBP-2 and -5 expression in BC and possible involvement of these genes in the development of resistance to adjuvant endocrine therapies.

Th1 epitope selection for clinically effective cancer vaccines

New cancer immunotherapies mark progress in our understanding of tumor biology and harnessing the immune system's management of self. However, protein- and peptide-based vaccines are not yet consistently efficacious. Recent work uncovers principles governing the genesis of T helper type-restrictive immunity to self-antigens elicited by vaccine epitopes, enabling vaccines to skew the balance from tolerogenic Type II (Th2) to inflammatory Type I (Th1) T cells, and invigorating this cancer immunotherapeutic approach.

Natural history of tumor growth and immune modulation in common spontaneous murine mammary tumor models

Recent studies in patients with breast cancer suggest the immune microenvironment influences response to therapy. We aimed to evaluate the relationship between growth rates of tumors in common spontaneous mammary tumor models and immune biomarkers evaluated in the tumor and blood. TgMMTV-neu and C3(1)-Tag transgenic mice were followed longitudinally from birth, and MPA-DMBA-treated mice from the time of carcinogen administration, for the development of mammary tumors. Tumor-infiltrating CD4(+) and CD8(+) T-cells, FOXP3(+) T-regulatory cells, and myeloid-derived suppressor cells were assessed by flow cytometry. Serum cytokines were evaluated in subsets of mice. Fine needle aspirates of tumors were collected and RNA was isolated to determine levels of immune and proliferation markers. Age of tumor onset and kinetics of tumor growth were significantly different among the models. Mammary tumors from TgMMTV-neu contained a lower CD8/CD4 ratio than that of other models (p < 0.05). MPA-DMBA-induced tumors contained a higher percentage of FOXP3(+) CD4(+) T-cells (p < 0.01) and MDSC (p < 0.001) compared with the other models. Individuals with significantly slower tumor growth demonstrated higher levels of Type I serum cytokines prior to the development of lesions compared to those with rapid tumor growth. Moreover, the tumors of animals with more rapid tumor growth demonstrated a significant increase in the expression of genes associated with Type II immunity than those with slower-progressing tumors. These data provide a foundation for the development of in vivo models to explore the relationship between endogenous immunity and response to standard therapies for breast cancer.

Dendritic cells, inflammation, and breast cancer

Solid tumors are well known for their genomic heterogeneity. Although some aspects of this derive from so-called driver mutations, it is now clear that tumor cells possess a seemingly limitless capacity to evade cell death pathway activation, maintain essential survival programming, and initiate resistance networks that block efficacy of cytotoxic and targeted therapy. Given this amazing survival capability, how then to design approaches for effective eradication of malignant cells? Also present within all solid tumors is a diverse assemblage of genomically stable immune cell types. Whereas some of these possess documented activities that foster tumor progression, others possess inherent activities that when favored lead to rapid tumor cell elimination. This review focuses on aspects of dendritic cell biology in solid tumors, especially breast cancers, which point to dendritic cells as a tractable tool to exploit for immune-based therapies.

Vaccination with ErbB-2 peptides prevents cancer stem cell expansion and suppresses the development of spontaneous tumors in MMTV-PyMT transgenic mice

ErbB-2 has been implicated as a target for cancer-initiating cells in breast and other cancers. ErbB-2-directed peptide vaccines have been shown to be effective in prevention of spontaneous tumorigenesis of breast in neu transgenic mouse model, and cellular immunity is proposed as a mechanism for the anti-tumor efficacy. However, there has been no explanation as to how immunity suppresses tumorigenesis from the early stage carcinogenesis, when ErbB-2 expression in breast is low. Here, we investigated a peptide-based vaccine, which consists of two MHC class II epitopes derived from murine ErbB-2, to prevent the occurrence of spontaneous tumors in breast and assess immune impact on breast cancer stem cells. Female MMTV-PyMT transgenic mice were immunized with either ErbB-2 peptide vaccine, or a peptide from tetanus toxoid, or PBS in immune adjuvant. ErbB-2 peptides vaccine completely suppressed spontaneous breast tumors, and the efficacy was correlated with antigen-specific T-cell and antibody responses. In addition, immune serum from the mice of ErbB-2 vaccine group had an inhibitory effect on mammosphere-forming capacity and signaling through ErbB-2 and downstream Akt pathway in ErbB-2 overexpressing mouse mammary cancer cells. We provide evidence that multi-epitope class II peptides vaccine suppresses tumorigenesis of breast potentially by inhibiting the growth of cancer stem cells. We also suggest that a strategy of inducing strong immune responses using multi-epitope ErbB-2-directed helper vaccine might be useful in preventing breast cancer recurrence.

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

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

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

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

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

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

Future directions in cancer prevention

Prevention of cancer remains the most promising strategy for reducing both its incidence and the mortality due to this disease. For more than four decades, findings from epidemiology, basic research and clinical trials have informed the development of lifestyle and medical approaches to cancer prevention. These include selective oestrogen receptor modulators and aromatase inhibitors for breast cancer, the 5-α-reductase inhibitors finasteride and dutasteride for prostate cancer, and the development of vaccines for viruses that are associated with specific cancers. Future directions include genetic, proteomic and other molecular approaches for identifying pathways that are associated with cancer initiation and development, as well as refining the search for immunologically modifiable causes of cancer.

Autoantibodies against insulin-like growth factor‑binding protein-2 as a serological biomarker in the diagnosis of lung cancer

Insulin-like growth factor-binding protein-2 (IGFBP-2) is considered to be a human tumor antigen, and the tumor-specific immunity of IGFBP-2 has been reported in several types of cancer. The purpose of this study was to evaluate whether autoantibodies to IGFBP-2 can be used as diagnostic markers in lung cancer. The results demonstrated that serum anti-IGFBP-2 autoantibody levels were significantly elevated in lung cancer (mean, 1,633.318 ng/ml; median, 1,651.462 ng/ml; range, 342.732–4932.582 ng/ml) compared with benign lung disease (1,210.139, 1,035.900, 547.596–2,331.167 ng/ml) and normal controls (1,303.369, 1,194.800, 528.200–2140.500 ng/ml). The sensitivity and specificity of anti-IGFBP-2 autoantibodies in diagnosing lung cancer was 73.2 and 60.6%, respectively. When serum IGFBP-2 and anti-IGFBP-2 autoantibody were used together in the diagnosis of lung cancer, it can increase the discriminative power for lung cancer with a sensitivity of 85.7% and a specificity of 57.5%. In conclusion, this study demonstrates that circulating anti-IGFBP-2 autoantibodies can be used as a potential biomarker in diagnosing lung cancer.

Elevated serum antibodies against insulin-like growth factor-binding protein-2 allow detecting early-stage cancers: evidences from glioma and colorectal carcinoma studies

BACKGROUND

Tumor-specific immunity of insulin-like growth factor-binding protein-2 (IGFBP-2) has been reported in several cancers. We aimed to assess the role of serum IGFBP-2 antibodies (IGFBP-2 Abs) in early cancer detection.

PATIENTS AND METHODS

Glioma and colorectal carcinoma (CRC) were used as models. Serum IGFBP-2 and IGFBP-2 Abs were measured in 260 tumor patients (145 gliomas, 45 colorectal polyps, and 70 CRCs) and 141 controls. Receiver operating characteristic curves were applied.

RESULTS

Serum IGFBP-2 Ab levels were significantly elevated in tumors (mean: 82 ng/ml, median: 17 ng/ml, range: 0-1387 ng/ml) compared with controls (11, 0, 0-212 ng/ml) (P < 0.0001) and higher in early than advanced cancers opposite of serum IGFBP-2 levels. IGFBP-2 Abs effectively discriminated between controls and grade II and III gliomas [area under the curve (AUC): 0.821-0.864; 95% confidence interval (CI) = 0.762-0.936; P < 0.0001], and CRC I-II (AUC: 0.668; 95% CI = 0.566-0.770; P = 0.002) as well as indicative of advanced polyps at high risk of CRC (AUC: 0.72; 95% CI = 0.630-0.811; P < 0.0001). The sensitivity and specificity for diagnosing grade II-III gliomas reached 66%-84% and 81%. Combined serum IGFBP-2 and IGFBP-2 Abs augmented the discriminative power of all stage tumors (AUC: 0.823), gliomas (AUC: 0.800), and CRCs (AUC = 0.917).

CONCLUSION

Our results first demonstrate IGFBP-2 Abs for early cancer detection and in combination of serum IGFBP-2 for improved cancer diagnosis.

Dendritic cell-activating vaccine adjuvants differ in the ability to elicit antitumor immunity due to an adjuvant-specific induction of immunosuppressive cells

PURPOSE

We questioned whether the vaccine adjuvant combination of TLR-7 ligand agonist, imiquimod, with granulocyte macrophage colony-stimulating factor (GM-CSF) would result in enhanced dendritic cell recruitment and activation with increased antigen-specific immunity as compared with either adjuvant used alone.

EXPERIMENTAL DESIGN

The adjuvant effects of GM-CSF and imiquimod were studied in ovalbumin (OVA) and MMTVneu transgenic mice using peptide-based vaccines. Type I immunity, serum cytokines, myeloid-derived suppressive cells (MDSC), and regulatory T cells (Treg) levels were examined.

RESULTS

Both GM-CSF and imiquimod equally induced local accumulation and activation of dendritic cells. Both adjuvants effectively enhanced OVA-specific T-cell responses. We further evaluated the antitumor efficacy of adjuvant GM-CSF and imiquimod immunizing against murine insulin-like growth factor-binding protein-2 (IGFBP-2), a nonmutated oncoprotein overexpressed in the tumors of MMTVneu transgenic mice. Tumor growth was significantly inhibited in the mice receiving IGFBP-2 peptides with GM-CSF (P = 0.000), but not in imiquimod vaccine-treated groups (P = 0.141). Moreover, the addition of imiquimod to GM-CSF negated the antitumor activity of the vaccine when GM-CSF was used as the sole adjuvant. While GM-CSF stimulated significant levels of antigen-specific T-helper cell (T(H))1, imiquimod induced elevated serum interleukin (IL)-10. Both MDSC and Tregs were increased in the imiquimod-treated but not GM-CSF-treated groups (P = 0.000 and 0.006, respectively). Depleting MDSC and Treg in animals immunized with imiquimod and IGFBP-2 peptides restored antitumor activity to the levels observed with vaccination using GM-CSF as the sole adjuvant.

CONCLUSION

Adjuvants may induce regulatory responses in the context of a self-antigen vaccine. Adjuvant triggered immunosuppression may limit vaccine efficacy and should be evaluated in preclinical models especially when contemplating combination approaches.

Therapeutic cancer vaccines and translating vaccinomics science to the global health clinic: emerging applications toward proof of concept

As vaccines evolve to be a more common treatment for some cancers, further research is needed to improve the process of developing vaccines and assessing response to treatment. Vaccinomics involves a wide-ranging integration of multiple high throughput technologies including transcriptional, translational, and posttranslational population-based assessments of the human genome, transcriptome, proteome, and immunome. Vaccinomics combines the fields of immunogenetics, immunogenomics, immunoproteomics, and basic immunology to create vaccines that are tailor made to an individual or groups of individuals. This broad range of omics applications to tumor immunology includes antigen discovery, diagnostic biomarkers, cancer vaccine development, predictors of immune response, and clinical response biomarkers. These technologies have aided in the advancement of cancer vaccine development, as illustrated in examples including NY-ESO-1 originally defined by SEREX, and HER2/neu peptides analyzed via high-throughput epitope prediction methods. As technology improves, it presents an opportunity to improve cancer immunotherapy on a global scale, and attention must also be given to utilize these high-throughput methods for the understanding of cancer and immune signatures across populations.

Polysaccharide krestin is a novel TLR2 agonist that mediates inhibition of tumor growth via stimulation of CD8 T cells and NK cells

PURPOSE

Polysaccharide krestin (PSK) is a mushroom extract that has been long used in Asia and recently in Western countries as a treatment for cancer due to its presumed immune potentiating effects. Although there have been reports of clinical responses after patients have ingested PSK, the mechanism of action of the agent remains undefined. The current study was undertaken to investigate the mechanism of the antitumor actions of PSK.

EXPERIMENTAL DESIGN

The immunostimulatory effect of PSK was first evaluated in vitro using splenocytes from neu transgenic mice and Toll-like receptor (TLR) 2 knockout (TLR2(-/-)) mice. Then the immunostimualtory and antitumor effect of PSK was determined using tumor-bearing neu transgenic mice, TLR2(-/-), and wild-type C57BL/6 mice.

RESULTS

We demonstrate that PSK is a selective TLR2 agonist, and the activation of dendritic cells (DC) and T cells by PSK is dependent on TLR2. Oral administration of PSK in neu transgenic mice significantly inhibits breast cancer growth. Selective depletion of specific cell populations suggests that the antitumor effect of PSK is dependent on both CD8(+) T cell and NK cells, but not CD4(+) T cells. PSK does not inhibit tumor growth in TLR2(-/-) mice suggesting that the antitumor effect is mediated by TLR2.

CONCLUSION

These results demonstrate that PSK, a natural product commonly used for the treatment of cancer, is a specific TLR2 agonist and has potent antitumor effects via stimulation of both innate and adaptive immune pathways.

Plasma insulin-like growth factor-binding protein-2 levels as diagnostic and prognostic biomarker of colorectal cancer

CONTEXT

Overexpression of IGF-II and IGF-binding protein (IGFBP)-2 has been reported in several cancers.

OBJECTIVE

We aimed to assess the roles of plasma IGF-II and IGFBP-2 levels as diagnostic and prognostic biomarkers and the impact of loss of imprinting (LOI) of IGF-II on the survival of colorectal cancer (CRC).

DESIGN

We conducted a case control and prospective cohort study for diagnostic and prognostic values, respectively.

PATIENTS AND SETTING

Plasma levels of IGF-II and IGFBP-2 were measured in 162 patients with CRC before surgery, in paired 15 patients after curative surgery, in 24 patients with advanced colon polyps, and in 114 healthy controls between 2003 and 2006 in National Taiwan University Hospital.

RESULTS

The area under the curve values of using IGFBP-2 as a diagnostic marker for advanced colon polyp and CRC were 0.654 [95% confidence interval (CI) = 0.547-0.76; P = 0.017] and 0.815 (95% CI = 0.766-0.864; P < 0.001), respectively. The sensitivity and specificity for diagnosing CRC were 80.2 and 64%, respectively, if the cutoff value of IGFBP-2 was 377 ng/ml. In the multivariate Cox proportional hazards regression model, higher IGFBP-2 levels were associated with increased risk of mortality [hazard ratio (HR) = 2.46; P = 0.017], whereas higher IGF-II levels were associated with reduced risk of mortality (HR = 0.42; P = 0.044). LOI of IGF-II was associated with increased risk of mortality (HR = 7.91; P = 0.014) in patients with stage IV disease.

CONCLUSIONS

IGFBP-2 is a potential diagnostic and prognostic biomarker of CRC. LOI of IGF-II is significantly associated with poor prognosis in patients with stage IV disease.

Evolving novel anti-HER2 strategies

The approval of trastuzumab for use in metastatic breast cancer marked a breakthrough in the understanding of the biology of the disease. However, like most cancer therapies, the disease finds a way to advance despite the treatments developed to eradicate it. Although trastuzumab has had a large effect on the treatment of early and advanced-stage disease, a substantial proportion of patients with HER2-positive breast cancer still progress after receiving the drug. Potential mechanisms of resistance to trastuzumab include bypass mechanisms, mutations of the HER2 target, masking of HER2 proteins, inhibition of insulin-like growth factor, and phosphatase and tensin homologue (PTEN) deficiency. Many therapies are being developed to target these mechanisms in patients with HER2-positive, trastuzumab-resistant breast cancer. Additionally, treatment strategies other than trastuzumab with unique mechanisms of action are being assessed in this specific group of patients. In this review, we discuss the emerging data assessing therapeutic approaches in the management of trastuzumab-resistant HER2-positive disease.

Immunomodulation of breast cancer via tumor antigen specific Th1

It has long been assumed that the immune system plays a role in tumor eradication, however, scant clinical evidence exists to support that hypothesis. In recent years, as the immune system and its specific effector cells are better defined, convincing data supporting immune surveillance is emerging. Several studies have shown that an "immune signature" in the tumor microenvironment is associated with a superior outcome in a variety of cancer types. Moreover, studies have suggested that T cells found in high density within the tumor parenchyma are also correlated with a survival benefit. The type of adaptive immune response implicated in improved cancer outcomes is a type 1 response. That is, adaptive immunity associated with T cells that secrete pro-inflammatory cytokines, such as IFN-gamma, which can not only support a proliferative antigen specific T cell response but also enhance "cross priming" by activating antigen presenting cells local to the tumor site. There are many methods available that will allow the development of clinical reagents designed to stimulate Th1 immunity; either by in vitro or in vivo manipulation. Clinical trials of a variety of immunotherapeutic strategies indicate that the generation of tumor antigen specific Th1 may be beneficial in inhibiting the growth of common solid tumors.

Concurrent trastuzumab and HER2/neu-specific vaccination in patients with metastatic breast cancer

PURPOSE

The primary objectives of this phase I/II study were to evaluate the safety and immunogenicity of combination therapy consisting of concurrent trastuzumab and human epidermal growth factor receptor 2 (HER2)/neu-specific vaccination in patients with HER2/neu-overexpressing metastatic breast cancer.

PATIENTS AND METHODS

Twenty-two patients with stage IV HER2/neu-positive breast cancer receiving trastuzumab therapy were vaccinated with an HER2/neu T-helper peptide-based vaccine. Toxicity was graded according to National Cancer Institute criteria, and antigen specific T-cell immunity was assessed by interferon gamma enzyme-linked immunosorbent spot assay. Data on progression-free and overall survival were collected.

RESULTS

Concurrent trastuzumab and HER2/neu vaccinations were well tolerated, with 15% of patients experiencing an asymptomatic decline in left ventricular ejection fraction below the normal range during combination therapy. Although many patients had pre-existing immunity specific for HER2/neu and other breast cancer antigens while treated with trastuzumab alone, that immunity could be significantly boosted and maintained with vaccination. Epitope spreading within HER2/neu and to additional tumor-related proteins was stimulated by immunization, and the magnitude of the T-cell response generated was significantly inversely correlated with serum transforming growth factor beta levels. At a median follow-up of 36 months from the first vaccine, the median overall survival in the study population has not been reached.

CONCLUSION

Combination therapy with trastuzumab and a HER2/neu vaccine is associated with minimal toxicity and results in prolonged, robust, antigen-specific immune responses in treated patients.

His-tag ELISA for the detection of humoral tumor-specific immunity

Background

The application of high throughput molecular techniques such as SEREX are resulting in the identification of a multitude of tumor associated antigens. As newly identified antigens are incorporated into a variety of clinical trials, standardization of immunologic monitoring methods becomes increasingly important. We questioned whether mammalian cell expression of a histadine-linked human protein could be used to produce antigen suitable for detecting tumor-specific humoral immunity and whether such an assay could be amenable to standardization for clinical use.

Methods

We designed a his-tagged capture ELISA based on lysate from genetically engineered CHO cells for detection of antibodies to insulin-like growth factor binding protein 2, a novel tumor antigen. We performed technical and preliminary clinical validation studies, including comparison to a standard indirect ELISA based on commercially prepared recombinant antigen.

Results

The his-tagged capture ELISA could be standardized. Precision experiments resulted in CVs < 15%. Linearity and calibration experiments demonstrated r² values of 0.99. In comparison to Western blot analysis, his-tag and indirect ELISA accurately identified 88% and 93% of samples, respectively. Sample concordance between capture and indirect assays was highly significant (p = 0.003). Furthermore, significantly greater levels of IGFBP-2 antibody immunity were found in cancer patients compared to normal controls (p = 0.008).

Conclusion

A genetically engineered cell lysate based ELISA can be amenable to standardization and can detect increased levels of antibody immunity to tumor-associated antigen in cancer patients compared to non tumor-bearing healthy controls.