Identification of tumor antigens as potential target antigens for immunotherapy by serological expression cloning

Increased absolute lymphocyte count, increased absolute neutrophil count and low platelet to lymphocyte ratio as predicting factors in the superior disease control of refractory/relapsing gynecologic malignancies with anti PD-1 therapy: 10 years of experience in a single institution

OBJECTIVE

Immune checkpoint inhibitors are rapidly being used in solid and hematologic malignancies, including gynecologic cancers. The high mortality and relapsing rates of advanced gynecologic malignancies remain a challenging issue. This study aimed to identify the predicting factors associated with survival prognosis and disease control in patients with refractory/relapsing (R/R) gynecologic malignancies receiving anti PD-1 therapy.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of 49 patients diagnosed with R/R gynecologic malignancies between July 2012 and June 2019 in Chang Gung Memorial Hospital, Taiwan. Among the 49 patients, 6 were excluded due to incomplete medical records or not receiving anti PD-1 therapy. The remaining 43 patients were further divided into responsive and non-responsive groups according to disease control for predicting prognostic factor analysis.

RESULTS

For the 43 cases, the median age at diagnosis and disease follow-up length were 54 years and 29 months, respectively. Among them, 23 (53%) were categorized into the responsive group, and the remaining 20 (47%) were categorized into the non-responsive group. The mortality rates were 17% and 25% in the responsive and non-responsive groups, respectively. The responsive group had significantly higher absolute lymphocyte count (ALC), higher absolute neutrophil count (ANC) and low platelet to lymphocyte ratio (PLR) than the non-responsive group. A superior long-term survival trend was also observed in the responsive group, but the difference was not statistically significant.

CONCLUSIONS

This study reinforced the hypothesis that high ALC, high ANC and low PLR are associated with superior disease control in patients with R/R gynecologic malignancies receiving anti PD-1 therapy.

HER2-antigen-specific humoral immune response in breast cancer lymphocytes transplanted in hu-PBL hIL-4 NOG mice

The status of humoral immunity of cancer patients is not clear compared to cellular immunity because the ability of specific antibody production is difficult to analyze in vitro. We previously developed a humanized mouse model to evaluate antigen-specific antibody production by transplanting human peripheral blood mononuclear cells (PBMCs) into NOG-hIL-4-Tg mice (hu-PBL hIL-4 NOG). In this study, these mice were transplanted with PBMCs derived from breast cancer patients (BC) and immunized with a human epidermal growth factor receptor 2 (HER2) peptide, CH401MAP, to analyze humoral immunity of BCs. The hu-PBL hIL-4 NOG mice recapitulated immune environment of BCs as the ratio of CD8+/CD4+T cells was lower and that of PD-1 + T cells was higher compared to healthy donors (HDs). Diverse clusters were detected in BC-mouse (BC-M) plasma components involving immunoglobulins and complements unlike HD-M, and there was a significant diversity in CH401MAP-specific IgG titers in BC-M. The number of B cell clones producing high CH401MAP-specific IgG was not increased by immunization in BC-M unlike HD-M. These results demonstrated that the humoral immunity of BCs appeared as diverse phenotypes different from HDs in hu-PBL hIL-4 NOG mice, which may provide important information for the study of personalized medicine.

Discovering novel lung cancer associated antigens and the utilization of their autoantibodies in detection of lung cancer

OBJECTIVE

The identification of tumor-associated antigens (TAAs) and their corresponding autoantibodies in lung cancer (LC) may expand our vision of cancer immunity. This study aims to screen novel TAAs to distinguish LC from the healthy population.

METHODS

In our previous study, 35 genes encoding LC-associated TAAs were identified from the serological analysis of recombinant cDNA expression libraries (SEREX), and Oncomine database was further used to identify potential genes in cancer progression. Autoantibody to TAAs were tested by enzyme-linked immunosorbent assay (ELISA) in sera from 1379 participants in validation set and verification set.

FINDINGS

Based on analysis of three independent microarrays in Oncomine, ten genes were consistently dysregulated in LC. The sera level and positive frequency of the anti-TOP2A, anti-ACTR3, anti-RPS6KA5 and anti-PSIP1 from LC patients were higher than normal control in validation set. The area under curve (AUC) of anti-TOP2A, anti-ACTR3, anti-RPS6KA5 and anti-PSIP1 was respectively 0.758, 0.787, 0.707, 0.668. The sensitivity of these four autoantibodies for LC detection ranged from 26.63 % to 32.07 % with the specificity over 90 %. Data from the verification set confirmed the results. Except that, the frequency of serum autoantibody against TOP2A (43.3 %) and ACTR3 (50.0 %) was significantly higher in early stage LC than late stage (23.6 % and 22.3 %, respectively).

CONCLUSION

TOP2A, ACTR3, RPS6KA5 and PSIP1 can elicit humoral immune response in LC and their autoantibodies have relationship with the tumorigenesis of LC. Anti-TOP2A and anti-ACTR3 have the potential to serve as a serological biomarkers in early stage LC.

Immunoproteomics Methods and Techniques

The varied landscape of the adaptive immune response is determined by the peptides presented by immune cells, derived from viral or microbial pathogens or cancerous cells. The study of immune biomarkers or antigens is not new, and classical methods such as agglutination, enzyme-linked immunosorbent assay, or Western blotting have been used for many years to study the immune response to vaccination or disease. However, in many of these traditional techniques, protein or peptide identification has often been the bottleneck. Recent progress in genomics and mass spectrometry have led to many of the rapid advances in proteomics approaches. Immunoproteomics describes a rapidly growing collection of approaches that have the common goal of identifying and measuring antigenic peptides or proteins. This includes gel-based, array-based, mass spectrometry-based, DNA-based, or in silico approaches. Immunoproteomics is yielding an understanding of disease and disease progression, vaccine candidates, and biomarkers. This review gives an overview of immunoproteomics and closely related technologies that are used to define the full set of protein antigens targeted by the immune system during disease.

MABp1 as a novel antibody treatment for advanced colorectal cancer: a randomised, double-blind, placebo-controlled, phase 3 study

BACKGROUND

MABp1, an antibody that targets interleukin 1α, has been associated with antitumour activity and relief of debilitating symptoms in patients with advanced colorectal cancer. We sought to establish the effect of MABp1 with a new primary endpoint in patients with advanced colorectal cancer.

METHODS

Eligible patients for the double-blind phase of this ongoing, placebo-controlled, randomised, phase 3 trial, had metastatic or unresectable disease, Eastern Cooperative Oncology Group performance status score 1 or 2, systemic inflammation, weight loss, and other disease-related morbidities associated with poor prognosis, and were refractory to oxaliplatin and irinotecan. Patients were randomly assigned 2:1 to receive either MABp1 or placebo. Randomisation codes were obtained from a centrally held list via an interactive web response system. Patients received an intravenous infusion of 7·5 mg/kg MABp1 or placebo given every 2 weeks for 8 weeks. The primary endpoint was assessed in patients who received at least one dose of MABp1 or placebo (modified intention-to-treat population), and was a composite of stable or increased lean body mass and stability or improvement in two of three symptoms (pain, fatigue, or anorexia) at week 8 compared with baseline measurements. This study is registered with ClinicalTrials.gov, number NCT02138422.

FINDINGS

Patients were enrolled between May 20, 2014, and Sept 2, 2015. The double-blind phase of the study was completed on Nov 3, 2015. Of 333 patients randomly assigned treatment, 207 received at least one dose of MABp1 and 102 at least one dose of placebo. 68 (33%) and 19 (19%) patients, respectively, achieved the primary endpoint (relative risk 1·76, 95% CI 1·12-2·77, p=0·0045). The most common grade 3-4 adverse events in the MABp1 group compared with in the placebo group were anaemia (eight [4%] of 207 vs five [5%] of 102 patients), increased concentration of alkaline phosphatase (nine [4%] vs two [2%]), fatigue (six [3%] vs seven [7%]), and increased concentration of aspartate aminotransferase (six [3%] vs two [2%]). After 8 weeks, 17 (8%) patients in the MABp1 group and 11 (11%) in the placebo group had died, but no death was judged to be related to treatment. The incidence of serious adverse events was not significantly different in the MABp1 group and placebo groups (47 [23%] vs 33 [32%], p=0·07).

INTERPRETATION

The primary endpoint was a useful means of measuring clinical performance in patients. MABp1 might represent a new standard in the management of advanced colorectal cancer.

FUNDING

XBiotech.

Immunoproteomics: current technology and applications

The varied landscape of the adaptive immune response is determined by the peptides presented by immune cells, derived from viral or microbial pathogens or cancerous cells. The study of immune biomarkers or antigens is not new and classical methods such as agglutination, enzyme-linked immunosorbent assay, or Western blotting have been used for many years to study the immune response to vaccination or disease. However, in many of these traditional techniques, protein or peptide identification has often been the bottleneck. Recent advances in genomics and proteomics, has led to many of the rapid advances in proteomics approaches. Immunoproteomics describes a rapidly growing collection of approaches that have the common goal of identifying and measuring antigenic peptides or proteins. This includes gel based, array based, mass spectrometry, DNA based, or in silico approaches. Immunoproteomics is yielding an understanding of disease and disease progression, vaccine candidates, and biomarkers. This review gives an overview of immunoproteomics and closely related technologies that are used to define the full set of antigens targeted by the immune system during disease.

Identification and characterization of human leukocyte antigen class I ligands in renal cell carcinoma cells

The presentation of tumor antigen-derived peptides by human leukocyte antigen (HLA) class I surface antigens on tumor cells is a key prerequisite to trigger effective T-cell responses in cancer patients. Multiple complementary strategies like cDNA and serological expression cloning, reverse immunology and different 'ome'-based methods have been employed to identify potential T-cell targets. This report focuses on a ligandomic profiling approach leading to the identification of 49 naturally processed HLA class I peptide ligands presented on the cell surface of renal cell carcinoma (RCC) cells. The source proteins of the defined HLA ligands are classified according to their biological function and subcellular localization. Previously established cDNA microarray data of paired tissue specimen of RCC and renal epithelium assessed the transcriptional regulation for 28 source proteins. In addition, HLA-A2-restricted, peptide-specific T cells directed against a HLA ligand derived from sulfiredoxin-1 (SRXN1) were generated, which were able to recognize and lyse ligand-presenting target cells in a HLA class I-restricted manner. Furthermore, tumor-infiltrating T cells isolated from a RCC patient were also able to kill SRXN1 expressing tumor cells. Thus, this experimental strategy might be suited to define potential candidate biomarkers and novel targets for T-cell-based immunotherapies of this disease.

Vaccine-induced antibody responses in patients with carcinoma

Cancer vaccines based on defined antigens are capable of inducing antibodies that recognize and kill tumor cells. Antibodies are ideally suited to address minimal residual disease, and vaccination in an adjuvant setting may favorably influence the outcome of a disease. The present article gives a short summary of antibody production by B cells, and the mechanism of action of antibodies, as well as a description of the current methods for measuring antibody responses and for assessing their antitumor efficacy in the context of clinical trials. It concludes with an overview of antibody responses induced by vaccines based on structurally defined tumor-associated antigens tested in patients with carcinomas. Correlation between antibody responses, T-cell responses and clinical outcome has been noted in a few studies, signaling the importance of vaccine design and adjuvants to exploit the interactions of the innate and adaptive immune system. However, humoral responses, which may provide a surrogate marker for T-helper responses and simplify monitoring of large Phase III trials, are still not or incompletely explored in many vaccination trials.

Immunogenicity of SEREX-identified antigens and disease outcome in pancreatic cancer

Despite spontaneous or vaccination-induced immune responses, pancreatic cancer remains one of the most deadly immunotherapy-resistant malignancies. We sought to comprehend the spectrum of pancreatic tumor-associated antigens (pTAAs) and to assess the clinical relevance of their immunogenicity. An autologous SEREX-based screening of a cDNA library constructed from a pancreatic T3N0M0/GIII specimen belonging to a long-term survivor (36 months) revealed 18 immunogenic pTAA. RT-PCR analysis displayed broad distribution of the identified antigens among normal human tissues. PNLIPRP2 and MIA demonstrated the most distinct pancreatic cancer-specific patterns. ELISA-based screening of sera for corresponding autoantibodies revealed that although significantly increased, the immunogenicity of these molecules was not a common feature in pancreatic cancer. QRT-PCR and immunohistochemistry characterized PNLIPRP2 as a robust acinar cell-specific marker whose decreased expression mirrored the disappearance of parenchyma in the diseased organ, but was not related to the presence of PNLIPRP2 autoantibodies. Analyses of MIA-known to be preferentially expressed in malignant cells-surprisingly revealed an inverse correlation between intratumoral gene expression and the emergence of autoantibodies. MIA(high) patients were autoantibody-negative and had shorter median survival when compared with autoantibody-positive MIA(low) patients (12 vs. 34 months). The observed pTAA spectrum comprised molecules associated with acinar, stromal and malignant structures, thus presenting novel targets for tumor cell-specific therapies as well as for approaches based on the bystander effects. Applying the concept of cancer immunoediting to interpret relationships between gene expression, antitumor immune responses, and clinical outcome might better discriminate between past and ongoing immune responses, consequently enabling prognostic stratification of patients and individual adjustment of immunotherapy.

Cancer/testis antigens can be immunological targets in clonogenic CD133+ melanoma cells

"Cancer stem cells" that resist conventional treatments may be a cause of therapeutic failure in melanoma. We report a subpopulation of clonogenic melanoma cells that are characterized by high prominin-1/CD133 expression in melanoma and melanoma cell lines. These cells have enhanced clonogenicity and self-renewal in vitro, and serve as a limited in vitro model for melanoma stem cells. In some cases clonogenic CD133(+) melanoma cells show increased expression of some cancer/testis (CT) antigens. The expression of NY-ESO-1 in an HLA-A2 expressing cell line allowed CD133(+) clonogenic melanoma cells to be targeted for killing in vitro by NY-ESO-1-specific CD8(+) T-lymphocytes. Our in vitro findings raise the hypothesis that if melanoma stem cells express CT antigens in vivo that immune targeting of these antigens may be a viable clinical strategy for the adjuvant treatment of melanoma.

Novel approaches for identifying target antigens of autoreactive human B and T cells

Antigen-specific immune responses in multiple sclerosis have been studied for decades, but the target antigens of the putatively autoaggressive B and T cells still remain elusive. Here, we summarize recent strategies which are based on the direct analysis of biopsy or autopsy specimens from patients. Since this material is extremely scarce, the experimental methods need to be exceptionally sensitive. We describe technologies to distinguish (auto) aggressive T cells from irrelevant bystander lymphocytes by analyzing clonal expansions in relation to the morphological location of the cells in the tissue lesions. We then discuss approaches to clone matching α- and β-chains of the antigen-specific T cell receptor (TCR) molecules from single T cells. This is necessary because usually, several clones are expanded and are diluted by many irrelevant cells. The matching TCR chains from individual T cells can be resurrected in hybridoma cells which may then be used for antigen searches. We discuss strategies to identify antigens of γδ- and αβ-TCR molecules, such as biochemical methods, candidate antigens, human leukocyte antigen requirements, synthetic peptide, and cDNA libraries. These strategies are tailored to characterize the antigens of the membrane-anchored, low-affinity TCR molecules. The strategies to identify (auto) reactive B cells or immunoglobulin (Ig) molecules are fundamentally different, because Ig molecules are water-soluble and have high affinities. We further discuss proteome-based approaches, techniques that analyze Ig-chains from single B cells, and a repertoire-based method that compares Ig-proteomes and Ig-transcriptomes. The first method detects Ig antigens directly, whereas the latter two methods allow reconstruction of Ig molecules, which can be used for antigen searches.

A human monoclonal antibody drug and target discovery platform for B-cell chronic lymphocytic leukemia based on allogeneic hematopoietic stem cell transplantation and phage display

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is the only potentially curative treatment available for patients with B-cell chronic lymphocytic leukemia (B-CLL). Here, we show that post-alloHSCT antibody repertoires can be mined for the discovery of fully human monoclonal antibodies to B-CLL cell-surface antigens. Sera collected from B-CLL patients at defined times after alloHSCT showed selective binding to primary B-CLL cells. Pre-alloHSCT sera, donor sera, and control sera were negative. To identify post-alloHSCT serum antibodies and subsequently B-CLL cell-surface antigens they recognize, we generated a human antibody-binding fragment (Fab) library from post-alloHSCT peripheral blood mononuclear cells and selected it on primary B-CLL cells by phage display. A panel of Fab with B-CLL cell-surface reactivity was strongly enriched. Selection was dominated by highly homologous Fab predicted to bind the same antigen. One Fab was converted to immunoglobulin G1 and analyzed for reactivity with peripheral blood mononuclear cells from B-CLL patients and healthy volunteers. Cell-surface antigen expression was restricted to primary B cells and up-regulated in primary B-CLL cells. Mining post-alloHSCT antibody repertoires offers a novel route to discover fully human monoclonal antibodies and identify antigens of potential therapeutic relevance to B-CLL and possibly other cancers. Trials described herein were registered at www.clinicaltrials.gov as nos. NCT00055744 and NCT00003838.

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

Breast cancer is immunogenic and well suited to treatment via immunomodulation. The disease is often treated to remission and time to relapse is generally measured in years in many cases. Immune-based therapeutics, such as cancer vaccines, may be able to affect the clinical progression of micrometastatic disease. Immune targets must be identified that have the potential to inhibit tumor growth. Insulin-like growth factor-binding protein-2 (IGFBP-2) has direct effects on breast cancer proliferation via stimulation of critical signaling pathways. We questioned whether IGFBP-2 was an immune target in breast cancer. IGFBP-2-specific IgG antibody immunity was preferentially detected in breast cancer patients compared with controls (P = 0.0008). To evaluate for the presence of T-cell immunity, we identified potential pan-HLA-DR binding epitopes derived from IGFBP-2 and tested the peptides for immunogenicity. The majority of epitopes elicited peptide-specific T cells in both patients and controls and had high sequence homology to bacterial pathogens. IGFBP-2 peptide-specific T cells could respond to naturally processed and presented IGFBP-2 protein, indicating that these peptides were native epitopes of IGFBP-2. Finally, both immunization with IGFBP-2 peptides as well as adoptive transfer of IGFBP-2-competent T cells mediated an antitumor effect in a transgenic mouse model of breast cancer. This is the first report of IGFBP-2 as a human tumor antigen that may be a functional therapeutic target in breast cancer.

Humoral immune responses against tumor-associated antigen OVA66 originally defined by serological analysis of recombinant cDNA expression libraries and its potentiality in cellular immunity

Immunotherapy for cancer relies on the identification of tumor antigens and efficacy of antitumor immune responses. Serological analysis of recombinant cDNA libraries (SEREX), which is based on the spontaneous humoral responses against potential tumor antigens, has provided a novel strategy for searching novel tumor-associated candidates. Through SEREX analysis, we have identified 24 distinct gene clones by immunoscreening of a cDNA library derived from an ovarian cancer patient. Among these genes, a novel gene, OVA66, was found to be expressed significantly higher in carcinoma samples from cancer patients than in normal controls. Comparing humoral responses to OVA66 between tumor patients and healthy donors, it has been shown that the IgG level against OVA66 was significantly elevated in the serum of cancer patients from different histological types of cancer. To determine whether SEREX-defined OVA66 can trigger promising cytotoxic T lymphocyte (CTL) responses, human leukocyte antigen (HLA)-A*0201-restricted T-cell epitopes were predicted through a computational algorithm. Of four predicted peptides, p306-314 (L235) possesses the ability to induce efficient peripheral blood lymphocyte (PBL)-derived CTL responses capable of specifically recognizing peptide-pulsed T2 cells and lysing carcinoma cell lines expressing both HLA-A2 and OVA66 as determined by cytotoxicity and enzyme-linked immunospot assay (ELISPOT). Taken together, our results demonstrate that the SEREX-defined tumor-associated antigen OVA66 can elicit humoral immunity and may also serve as a potential candidate for T-cell-based immunotherapy for cancer.

Prowling wolves in sheep's clothing: the search for tumor stem cells

The importance of a subset of cells which have ‘stem like’ characteristics and are capable of tumor initiation has been reported for a range of tumors. Isolation of these tumor-initiating cells (TICs) has largely been based on differential cell surface protein expression. However, there is still much debate on the functional significance of these markers in initiating tumors, as many properties of tumor initiation are modified by cell-cell interactions. In particular, the relationship between TICs and their microenvironment is poorly understood but has therapeutic implications, as the microenvironment can maintain tumor cells in a prolonged period of quiescence. However, a major limitation in advancing our understanding of the crosstalk between TICs and their microenvironment is the lack of sensitive techniques which allow thein vivotracking and monitoring of TICs. Application of newin vivocellular and molecular imaging technologies holds much promise in uncovering the mysteries of TIC behavior at the three-dimensional level. This review will describe recent advances in our understanding of the TIC concept and how the application ofin vivoimaging techniques can advance our understanding of the biological fate of TICs. A supplementary resource guide describing TICs from different malignancies is also presented.

Application of protein microarrays for multiplexed detection of antibodies to tumor antigens in breast cancer

There is strong preclinical evidence that cancer, including breast cancer, undergoes immune surveillance. This continual monitoring, by both the innate and the adaptive immune systems, recognizes changes in protein expression, mutation, folding, glycosylation, and degradation. Local immune responses to tumor antigens are amplified in draining lymph nodes, and then enter the systemic circulation. The antibody response to tumor antigens, such as p53 protein, are robust, stable, and easily detected in serum; may exist in greater concentrations than their cognate antigens; and are potential highly specific biomarkers for cancer. However, antibodies have limited sensitivities as single analytes, and differences in protein purification and assay characteristics have limited their clinical application. For example, p53 autoantibodies in the sera are highly specific for cancer patients, but are only detected in the sera of 10-20% of patients with breast cancer. Detection of p53 autoantibodies is dependent on tumor burden, p53 mutation, rapidly decreases with effective therapy, but is relatively independent of breast cancer subtype. Although antibodies to hundreds of other tumor antigens have been identified in the sera of breast cancer patients, very little is known about the specificity and clinical impact of the antibody immune repertoire to breast cancer. Recent advances in proteomic technologies have the potential for rapid identification of immune response signatures for breast cancer diagnosis and monitoring. We have adapted programmable protein microarrays for the specific detection of autoantibodies in breast cancer. Here, we present the first demonstration of the application of programmable protein microarray ELISAs for the rapid identification of breast cancer autoantibodies.

The tumor antigen repertoire identified in tumor-bearing neu transgenic mice predicts human tumor antigens

FVB/N mice transgenic for nontransforming rat neu develop spontaneous breast cancers that are neu positive and estrogen receptor negative, mimicking premenopausal human breast cancer. These animals have been widely used as a model for immunobased therapies targeting HER-2/neu. In this study, we used serological analysis of recombinant cDNA expression libraries to characterize the antigenic repertoire of neu transgenic (neu-tg) mice and questioned the ability of this murine model to predict potential human tumor antigens. After screening 3 x 10(6) clones from 3 different cDNA libraries, 15 tumor antigens were identified, including cytokeratin 2-8, glutamyl-prolyl-tRNA synthetase, complement C3, galectin 8, and serine/threonine-rich protein kinase 1. Multiple proteins involved in the Rho/Rho-associated, coiled coil-containing protein kinase (Rock) signal transduction pathway were found to be immunogenic, including Rock1, Rho/Rac guanine nucleotide exchange factor 2, and schistosoma mansoni adult worm antigen preparation 70. All of the identified antigens are self-proteins that are expressed in normal tissues in addition to breast tumors and the majority of the antigens are intracellular proteins. More than half of the mouse tumor antigens have human homologues that have been reported previously as tumor antigens. Finally, the tumor-specific antibody immunity and marked immune cell infiltration that was observed in mice with spontaneous tumors were not observed in mice with transplanted tumors. Our results indicate that neu-tg mice bearing spontaneous tumors develop humoral immunity to their tumors similar to cancer patients and that tumor antigens identified in transgenic mouse may predict immunogenic human homologues.

NY-BR-1 protein expression in breast carcinoma: a mammary gland differentiation antigen as target for cancer immunotherapy

NY-BR-1 is a recently identified differentiation antigen of the mammary gland. To use NY-BR-1 for T-cell-based immunotherapy, analysis of its co-expression with HLA class I antigens is required. In the present tissue microarray study, primary breast cancers (n = 1,444), recurrences (n = 88), lymph node (n = 525) and distant metastases (n = 91) were studied for NY-BR-1 expression using a novel monoclonal antibody. NY-BR-1 expression was compared with prognosis, estrogen receptor, HER2-status, EGFR and HLA class I antigen expression. NY-BR-1 was more frequently expressed in grade 1 (82%) than in grade 2 (69%) and grade 3 (46%) carcinomas (P < 0.0001). Moreover, NY-BR-1 expression correlated directly with estrogen receptor expression (P < 0.0001) and inversely correlated with HER2-status and EGFR expression (P < 0.0001 for both). Considering high expression level of co-expression, 198/1,321 (15%) primary breast carcinomas and 4/65 (6%) distant metastases expressed NY-BR-1 and HLA class I, suggesting that active immunotherapy can be applied to about 10% of breast cancer patients. Survival analysis showed an association of NY-BR-1 expression with better patient outcome (P = 0.015). No difference between NY-BR-1 expression of primary tumors and metastases could be found, indicating that the presence of NY-BR-1 in metastases can be deduced from their corresponding primary. Forty-three paired biopsies taken from patients before and after chemotherapy suggest that NY-BR-1 expression is not influenced by preceding chemotherapy (kappa = 0.89, P < 0.0001). In summary, the co-expression of NY-BR-1 with HLA class I antigens and its expression in metastases without modification by chemotherapy suggest that NY-BR-1 targeted immunotherapy represents a viable strategy in addition to other targeted cancer drug therapies of breast cancer.

Identification of T-cell epitopes for cancer immunotherapy

The effectiveness of T-cell-mediated immunotherapy of cancer depends on both an optimal immunostimulatory context of the therapy and the proper selection with respect to quality and quantity of the targeted tumor-associated antigens (TAA), and, more precisely, the T-cell epitopes contained in these tumor proteins. Our progressing insight in human leukocyte antigen (HLA) class I and class II antigen processing and presentation mechanisms has improved the prediction by reverse immunology of novel cytotoxic T lymphocyte and T-helper cell epitopes within known antigens. Computer algorithms that in silico predict HLA class I and class II binding, proteasome cleavage patterns and transporter associated with antigen processing translocation are now available to expedite epitope identification. The advent of genomics allows a high-throughput screening for tumor-specific transcripts and mutations, with that identifying novel shared and unique TAA. The increasing power of mass spectrometry and proteomics will lead to the direct identification from the tumor cell surface of numerous novel tumor-specific HLA class I and class II presented ligands. Together, the expanded repertoire of tumor-specific T-cell epitopes will enable more precise immunomonitoring and the development of effective epitope-defined adoptive T-cell transfer and multi-epitope-based vaccination strategies targeting epitopes derived from a wider diversity of TAA presented in a broader array of HLA molecules.

Immunotherapy of myeloid leukaemia

The treatment of myeloid leukaemia has progressed in recent years with the advent of donor leukocyte infusions (DLI), haemopoietic stem cell transplants (HSCTs) and targeted therapies. However, relapse has a high associated morbidity rate and a method for removing diseased cells in first remission, when a minimal residual disease state is achieved and tumour load is low, has the potential to extend remission times and prevent relapse especially when used in combination with conventional treatments. Acute myeloid leukaemia (AML) and myelodysplastic syndrome (MDS) are heterogeneous diseases which lack one common molecular target while chronic myeloid leukaemia (CML) patients have experienced prolonged remissions through the use of targeted therapies which remove BCR-ABL(+) cells effectively in early chronic phase. However, escape mutants have arisen and this therapy has little effectivity in the late chronic phase. Here we review the immune therapies which are close to or in clinical trials for the myeloid leukaemias and describe their potential advantages and disadvantages.

Targeting serum antibody for cancer diagnosis: a focus on colorectal cancer

The ability of the immune system to magnify the appearance of disease by generating relatively large amounts of antibody in response to small amounts of disease makes it a natural biosensor, and serum antibodies have emerged as promising biomarkers for the detection of cancer. This review summarizes recent progress in targeting serum antibodies for cancer diagnosis, with a particular focus on colorectal cancer (CRC). Several serum antibodies have been detected at increased levels in CRC patients, including p53, carcinoembryonic antigen, Ras, topoisomerase II-alpha, histone deacetylase 3 and 5, ubiquitin C-terminal hydrolase L3, tropomyosin and cyclin B1. As each antibody is only present in a limited proportion of patients (usually < 40%), a combination of serum antibodies that defines the 'immunological signature' of cancer needs to be developed. High-throughput methods to identify new serum antibodies for cancer diagnosis are also reviewed.

Biomarker discovery using protein microarray technology platforms: antibody-antigen complex profiling

Protein microarrays represent an important new tool in proteomic systems biology. This review focuses on the contributions of protein microarrays to the discovery of novel disease biomarkers through antibody-based assays. Of particular interest is the use of protein microarrays for immune response profiling, through which a disease-specific antibody repertoire may be defined. The antigens and antibodies revealed by these studies are useful for clinical assay development, with enormous potential to aid in diagnosis, prognosis, disease staging and treatment selection. The discovery and characterization of novel biomarkers specifically tailored to disease type and stage are expected to enable personalized medicine by facilitating preventative medicine, predictive diagnostics and individualized curative therapies.

Expression of the breast differentiation antigen NY-BR-1 in a phyllodes tumor of the vulva

We describe a phyllodes tumor of borderline malignancy in the labium majus of a 49-year-old woman. The histogenetic origin of phyllodes tumors in the vulva is controversial. Strong immunoreactivity for NY-BR-1, a novel breast differentiation antigen, was demonstrated within the epithelial components of the phyllodes tumor. A similar expression pattern was observed in mammary-like glands of the vulva. These findings provide further evidence that phyllodes tumors of the vulva might derive from mammary-like glands in the labium majus or from ectopic breast tissue.

Melanocyte differentiation antigen RAB38/NY-MEL-1 induces frequent antibody responses exclusively in melanoma patients

Expression pattern and immunogenicity are critical issues that define tumor antigens as diagnostic markers and potential targets for immunotherapy. The development of SEREX (serological analysis of recombinant expression libraries) has provided substantial progress in the identification of tumor antigens eliciting both cellular and humoral immune responses in cancer patients. By SEREX, we have previously identified RAB38/NY-MEL-1 as a melanocyte differentiation antigen that is highly expressed in normal melanocytes and melanoma tissues but not in other normal tissues or cancer types. In this study, we further demonstrate that RAB38/NY-MEL-1 is strongly immunogenic, leading to spontaneous antibody responses in a significant proportion of melanoma patients. The immune response occurs solely in malignant melanoma patients and was not detected in patients with other diseases, such as vitiligo, affecting melanocytes. Fine analysis of the spontaneous anti-RAB38/NY-MEL-1 antibody response reveals a polyclonal B cell recognition targeting various epitopes, although a dominant immunogenic region was preferentially recognized. Interestingly, our data indicate that this recognition is not rigid in the course of a patient's response, as the dominant epitope changes during the disease evolution. Implications for the understanding of spontaneous humoral immune responses are discussed.

An unconventional antigen translated by a novel internal ribosome entry site elicits antitumor humoral immune reactions

Self-tumor Ags that elicit antitumor immune responses in responses to IFN-alpha stimulation remain poorly defined. We screened a human testis cDNA library with sera from three polycythemia vera patients who responded to IFN-alpha and identified a novel Ag, MPD6. MPD6 belongs to the group of cryptic Ags without conventional genomic structure and is encoded by a cryptic open reading frame located in the 3'-untranslated region of myotrophin mRNA. MPD6 elicits IgG Ab responses in a subset of polycythemia vera patients, as well as patients with chronic myelogenous leukemia and prostate cancer, suggesting that it is broadly immunogenic. The expression of myotrophin-MPD6 transcripts was up-regulated in some tumor cells, but only slightly increased in K562 cells in response to IFN-alpha treatment. By using bicistronic reporter constructs, we showed that the translation of MPD6 was mediated by a novel internal ribosome entry site (IRES) upstream of the MPD6 reading frame. Furthermore, the MPD6-IRES-mediated translation, but not myotrophin-MPD6 transcription, was significantly up-regulated in response to IFN-alpha stimulation. These findings demonstrate that a novel IRES-mediated mechanism may be responsible for the translation of unconventional self-Ag MPD6 in responsive to IFN-alpha stimulation. The eliciting antitumor immune response against unconventional Ag MPD6 in patients with myeloproliferative diseases suggests MPD6 as a potential target of novel immunotherapy.

Immunoprevention of cancer

This article discusses the current understanding of the interactions between tumors and cells of the immune system, particularly at the early stages of carcinogenesis. A growing body of data suggests that these interactions help shape the eventual development of tumors. Inflammation is a common feature of several cancers, and the immune system can serve as a two-edged sword against cancer, capable of supporting and suppressing cancer. Data from human studies show that the immune system is capable of detecting the smallest expansions of transformed cells, well before the development of clinical cancer. These advances suggest a need to change the current emphasis for harnessing antitumor immunity from therapy to prevention of cancers.

Preferential nuclear and cytoplasmic NY-BR-1 protein expression in primary breast cancer and lymph node metastases

PURPOSE

NY-BR-1 is a recently isolated differentiation antigen, which is expressed in normal mammary tissue and in breast cancer. However, current data are based on RT-PCR analysis and nothing is known about the presence of NY-BR-1 on a protein level. We previously generated a monoclonal antibody to NY-BR-1 to study the protein expression of NY-BR-1.

METHODS

In our immunohistochemical study, NY-BR-1 was analyzed in normal tissues, various tumor types, 124 primary breast cancers, and 37 paired lymph node metastases.

RESULTS

Among normal tissues, NY-BR-1 was present solely in ductal epithelium of the breast. In tumors, carcinoma in situ and invasive carcinoma of the breast were NY-BR-1 positive whereas other tumors and normal tissues were negative. Sixty percent of invasive breast carcinomas were NY-BR-1 positive, displaying cytoplasmic and/or nuclear immunoreactivity. This coexpression was verified by confocal microscopy. Although the monoclonal antibody identified intratumoral heterogeneity, a majority (72%) of NY-BR-1-positive carcinomas revealed immunoreactivity in >50% of the tumor cells. NY-BR-1 expression was more frequent in estrogen receptor-positive and lymph node-negative primary carcinomas (P < 0.05 each) and was more common in grade 1 (77%) than in grade 2 (63%) or grade 3 (50%) carcinomas (P < 0.05). This suggests that NY-BR-1 expression is lost with tumor progression. Forty-nine percent of lymph node metastases were NY-BR-1 positive.

CONCLUSION

This study supports the notion that NY-BR-1 is a differentiation antigen of the breast, which is present in normal and tumorous mammary epithelium. The organ-specific expression of NY-BR-1 and its high prevalence in metastases indicate that it could be a valuable target for cancer immunotherapy.

Serological identification and bioinformatics analysis of immunogenic antigens in multiple myeloma

Identifying appropriate tumor antigens is critical to the development of successful specific cancer immunotherapy. Serological analysis of tumor antigens by a recombinant cDNA expression library (SEREX) allows the systematic cloning of tumor antigens recognized by the spontaneous autoantibody repertoire of cancer patients. We applied SEREX to the cDNA expression library of cell line HMy2, which led to the isolation of six known characterized genes and 12 novel genes. Known genes, including ring finger protein 167, KLF10, TPT1, p02 protein, cDNA FLJ46859 fis, and DNMT1, were related to the development of different tumors. Bioinformatics was performed to predict 12 novel MMSA (multiple myeloma special antigen) genes. The prediction of tumor antigens provides potential targets for the immunotherapy of patients with multiple myeloma (MM) and help in the understanding of carcinogenesis. Crude lysate ELISA methodology indicated that the optical density value of MMSA-3 and MMSA-7 were significantly higher in MM patients than in healthy donors. Furthermore, SYBR Green real-time PCR showed that MMSA-1 presented with a high number of copy messages in MM. In summary, the antigens identified in this study may be potential candidates for diagnosis and targets for immunotherapy in MM.

Reverse immunology approach for the identification of CD8 T-cell-defined antigens: advantages and hurdles

One of the challenges of tumour immunology remains the identification of strongly immunogenic tumour antigens for vaccination. Reverse immunology, that is, the procedure to predict and identify immunogenic peptides from the sequence of a gene product of interest, has been postulated to be a particularly efficient, high-throughput approach for tumour antigen discovery. Over one decade after this concept was born, we discuss the reverse immunology approach in terms of costs and efficacy: data mining with bioinformatic algorithms, molecular methods to identify tumour-specific transcripts, prediction and determination of proteasomal cleavage sites, peptide-binding prediction to HLA molecules and experimental validation, assessment of the in vitro and in vivo immunogenic potential of selected peptide antigens, isolation of specific cytolytic T lymphocyte clones and final validation in functional assays of tumour cell recognition. We conclude that the overall low sensitivity and yield of every prediction step often requires a compensatory up-scaling of the initial number of candidate sequences to be screened, rendering reverse immunology an unexpectedly complex approach.

Antibodies as oncogenes: a hypothesis

We would like to put forward the hypothesis that cancer patients may produce autoantibodies that promote uncontrolled cell growth and thereby function as oncogenes. Dying cells release proteins that stimulate the production of autoantibodies, an event also known to occur during the earliest stages of tumor growth. If some of these autoantibodies are directed against cell surface hormone receptors, they could oligomerize the receptors and inadvertently transmit growth signals. The abnormal signals could result in uncontrolled cell proliferation and, eventually, oncogenesis. Thus, some specific autoantibodies from among the large repertoires of autoantibodies present in the sera of cancer patients are, in reality, oncogenes. If such oncogenic autoantibodies are indeed present and can be identified, inhibition of their molecular action may be an effective therapeutic modality.

Proteomics in cancer vaccine development

Proteomics is a new scientific field aimed at the large-scale characterization of the protein constituents of biologic systems. It facilitates comparisons between different protein preparations by searching for minute differences in their protein expression repertoires and the patterns of their post-translational modifications. These attributes make proteomics perfectly suited for searching for proteins and peptides expressed exclusively or preferentially in cancer cells as candidates for cancer vaccines. The main proteomics technologies include 2D polyacrylamide gel electrophoresis, multidimensional high-performance liquid chromatography, mass spectrometry and protein arrays. Proteomics technologies used to analyze cancer culture cells, fresh tumor specimens, human leukocyte antigen peptides, serum and serum antibodies (serologic proteomics) have successfully identified tumor markers. Turning the potential vaccine candidates identified by proteomics technologies into clinical treatments awaits demonstration.

Antibody Immunity to the p53 Oncogenic Protein Is a Prognostic Indicator in Ovarian Cancer

Purpose

Presence of intratumoral T-cell infiltration has been linked to improved survival in ovarian cancer patients. We questioned whether antibody immunity specific for ovarian cancer tumor antigens would predict disease outcome. We evaluated humoral immune responses against ovarian cancer antigens p53, HER-2/neu, and topoisomerase IIα.

Patients and Methods

Serum was collected from 104 women (median age, 59 years; range, 34 to 89 years) at the time of their initial definitive surgery for ovarian cancer. Serum was analyzed by enzyme-linked immunosorbent assay for antibodies to p53, HER-2/neu, and topoisomerase IIα proteins. Antibody immunity to tetanus toxoid was assessed as a control. The incidence of humoral immunity at the time of diagnosis to any of these three antigens was tabulated. For patients with advanced-stage disease (III/IV), correlation was made between the presence of tumor-specific immunity at the time of diagnosis and overall survival. Patients were followed for a median of 1.8 years.

Results

Multivariate analysis showed the presence of p53 antibodies to be an independent variable for prediction of overall survival in advanced-stage patients. Overall survival was significantly higher for patients with antibodies to p53 when compared with patients without p53 antibodies (P = .01). The median survival for p53 antibody-positive patients was 51 months (95% CI, 23.5 to 60.5 months) compared with 24 months (95% CI, 19.4 to 28.6 months) for patients without antibodies to p53.

Conclusion

Data presented here demonstrate that advanced stage ovarian cancer patients can have detectable tumor-specific antibody immunity and that immunity to p53 may predict improved overall survival in patients with advanced-stage disease.

Direct production and purification of T7 phage display cloned proteins selected and analyzed on microarrays

Phage display technology has emerged into a powerful tool for identifying proteins with specific binding properties. This technology adds amino acid sequences to the carboxy terminus of a phage capsid protein, thus generating a fusion protein displayed on the surface of the phage. Here, we have developed a high-throughput strategy to synthesize purified protein that solves many of the problems associated with crude phage lysates. Phage DNA was used as a template for a nested PCR that added the T7 promoter, ribosome binding site, and a His6-tag. The PCR product was then used as a template for in vitro transcription/translation. The resulting His6-tagged recombinant protein was then purified by nickel affinity chromatography. The functionality of the purified protein was verified using protein microarray analysis.

Determination of Thrombopoietin-Derived Peptides Recognized by Both Cellular and Humoral Immunities in Healthy Donors and Patients with Thrombocytopenia

Thrombopoietin (TPO) is a cytokine that promotes megakaryocytopoiesis and thrombopoiesis and is considered a drug suitable for patients with thrombocytopenia. However, unexpected severe thrombocytopenia has developed in some healthy individuals participating in phase I clinical trials with a pegylated recombinant human megakaryocyte growth factor (PEG-rHuMGDF) that contained the first 163 amino acids of endogenous TPO, which resulted in hampering the further development of clinical trials. Autoimmune responses to PEG-rHuMGDF, which cross-reacted with endogenous TPO, were suggested to be involved in this rare but severe adverse event, although the immunogenic epitopes have not yet been determined. To better understand the molecular basis of such autoimmune reactions, we investigated the reactivity of 18 TPO-derived peptides with HLA-A2-binding motifs to plasma and T cells, both from patients with thrombocytopenia (n=24) and from healthy donors (HDs) (n=24). Four peptides, including those possessing amino acids in receptor-binding sites, were preferentially reactive to plasma from at least 20% of the patients, whereas one peptide at position 101-109 was equally reactive to those of the patients and the HDs. Each of the five peptides had the ability to induce peptide-specific cytotoxic T lymphocytes (CTLs) in both groups, albeit with less frequency among the patients. More important, each of these five peptides had the ability to induce HLA-A2-restricted and peptide-specific CTL activity reactive to cells that produce TPO. These results may provide new insights to gain a better understanding of autoimmune reactions to TPO.

Immunotherapy: bewitched, bothered, and bewildered no more

The field of immunotherapy holds clear promise not only for the development of new approaches to cancer and other diseases, but also for providing fundamental insight into the human immune response. In order for this promise to be realized, however, the scientific community must overcome an array of challenges. These challenges reflect not only the difficulties inherent in conducting investigations in human patients, but also difficulties created by the culture and practice of our own institutions, reward structure, and funding mechanisms. We suggest steps to be taken to reinvigorate basic research in human subjects as part of the mainstream of science.