Autoantibody Signatures Research Articles

Autoantibody Signatures Involving Glycolysis and Splicesome Proteins Precede a Diagnosis of Breast Cancer among Postmenopausal Women

We assessed the autoantibody repertoire of a mouse model engineered to develop breast cancer and the repertoire of autoantibodies in human plasmas collected at a preclinical time point and at the time of clinical diagnosis of breast cancer. In seeking to identify common pathways, networks, and protein families associated with the humoral response, we elucidated the dynamic nature of tumor antigens and autoantibody interactions. Lysate proteins from an immortalized cell line from a MMTV-neu mouse model and from MCF7 human breast cancers were spotted onto nitrocellulose microarrays and hybridized with mouse and human plasma samples, respectively. Immunoglobulin-based plasma immunoreactivity against glycolysis and spliceosome proteins was a predominant feature observed both in tumor-bearing mice and in prediagnostic human samples. Interestingly, autoantibody reactivity was more pronounced further away than closer to diagnosis. We provide evidence for dynamic changes in autoantibody reactivity with tumor development and progression that may depend, in part, on the extent of antigen-antibody interactions.

Significance of Anti-retinal Autoantibodies in Cancer-associated Retinopathy with Gynecological Cancers

BackgroundThe presence of autoantibodies (AAbs) is the primary serological indicator of autoimmunity. Cancer-associated retinopathy (CAR) is associated with AAbs and different types of cancer. The goal of the study was to examine the profile of serum autoantibodies in women with gynecological cancers with and without paraneoplastic visual manifestation.MethodsRetrospective studies of a cohort of 46 women with symptoms of CAR and gynecological tumors, including endometrial, cervical, ovarian, and fallopian tubes, 111 women with similar tumors without symptoms of CAR, and 60 age-matched healthy controls. Presence of serum AAbs and the identity of targeted antigens were performed by western blotting and their significance was evaluated using an Fisher’s exact test.ResultsThe patients with gynecological CAR had the highest proportion of seropositivity (80%), followed by patients with gynecological cancers without CAR (61%) and healthy controls (58%). Differences in recognition frequencies were found for 17 antigens and 5 retinal antigens were frequently targeted: enolase, aldolase C, carbonic anhydrase II, recoverin and GAPDH. The occurrence of anti-glycolytic enzymes was 2-3 times more frequent in CAR and cancer patients than healthy controls. Anti-recoverin AAbs were prevalent in endometrial CAR. Anti-CAII antibodies were not significantly different between groups of women. In this cohort, cancer was diagnosed before the onset of retinopathy with latency from 2 months to 30 years. The discovery of the ovarian and endometrial cancers and manifestation of visual problems often coincided but Fallopian tube carcinoma was found after visual onset.ConclusionNew retinal targets were identified for gynecological CAR. Each gynecological-CAR has its own autoantibody profile different from non-CAR profile, implying that a complex autoantibody signature may be more predictable for diagnosis than a singular AAb. Specific anti-retinal AAbs were most prevalent in women with CAR but their profiles were not fully distinguished from cancer controls.

Tumor-associated autoantibodies as diagnostic and prognostic biomarkers

In the process of tumorigenesis, normal cells are remodeled to cancer cells and protein expression patterns are changed to those of tumor cells. A newly formed tumor microenvironment elicits the immune system and, as a result, a humoral immune response takes place. Although the tumor antigens are undetectable in sera at the early stage of tumorigenesis, the nature of an antibody amplification response to antigens makes tumor-associated autoantibodies as promising early biomarkers in cancer diagnosis. Moreover, the recent development of proteomic techniques that make neo-epitopes of tumor-associated autoantigens discovered concomitantly has opened a new area of ‘immuno-proteomics’, which presents tumor-associated autoantibody signatures and confers information to redefine the process of tumorigenesis. In this article, the strategies recently used to identify and validate serum autoantibodies are outlined and tumor-associated antigens suggested until now as diagnostic/prognostic biomarkers in various tumor types are reviewed. Also, the meaning of autoantibody signatures and their clinical utility in personalized medicine are discussed. [BMB Reports 2012; 45(12): 677-685]

An Integrated Genome-Wide Approach to Discover Tumor-Specific Antigens as Potential Immunologic and Clinical Targets in Cancer

Tumor-specific antigens (TSA) are central elements in the immune control of cancers. To systematically explore the TSA genome, we developed a computational technology called heterogeneous expression profile analysis (HEPA), which can identify genes relatively uniquely expressed in cancer cells in contrast to normal somatic tissues. Rating human genes by their HEPA score enriched for clinically useful TSA genes, nominating candidate targets whose tumor-specific expression was verified by reverse transcription PCR (RT-PCR). Coupled with HEPA, we designed a novel assay termed protein A/G-based reverse serological evaluation (PARSE) for quick detection of serum autoantibodies against an array of putative TSA genes. Remarkably, highly tumor-specific autoantibody responses against seven candidate targets were detected in 4% to 11% of patients, resulting in distinctive autoantibody signatures in lung and stomach cancers. Interrogation of a larger cohort of 149 patients and 123 healthy individuals validated the predictive value of the autoantibody signature for lung cancer. Together, our results establish an integrated technology to uncover a cancer-specific antigen genome offering a reservoir of novel immunologic and clinical targets.

Early detection of cancer in the general population: a blinded case–control study of p53 autoantibodies in colorectal cancer

Background:Recent reports from cancer screening trials in high-risk populations suggest that autoantibodies can be detected before clinical diagnosis. However, there is minimal data on the role of autoantibody signatures in cancer screening in the general population.Methods:Informative p53 peptides were identified in sera from patients with colorectal cancer using an autoantibody microarray with 15-mer overlapping peptides covering the complete p53 sequence. The selected peptides were evaluated in a blinded case–control study using stored serum from the multimodal arm of the United Kingdom Collaborative Trial of Ovarian Cancer Screening where women gave annual blood samples. Cases were postmenopausal women who developed colorectal cancer following recruitment, with 2 or more serum samples preceding diagnosis. Controls were age-matched women with no history of cancer.Results:The 50 640 women randomised to the multimodal group were followed up for a median of 6.8 (inter-quartile range 5.9–8.4) years. Colorectal cancer notification was received in 101 women with serial samples of whom 97 (297 samples) had given consent for secondary studies. They were matched 1 : 1 with 97 controls (296 serial samples). The four most informative peptides identified 25.8% of colorectal cancer patients with a specificity of 95%. The median lead time was 1.4 (range 0.12–3.8) years before clinical diagnosis.Conclusion:Our findings suggest that in the general population, autoantibody signatures are detectable during preclinical disease and may be of value in cancer screening. In colorectal cancer screening in particular, where the current need is to improve compliance, it suggests that p53 autoantibodies may contribute towards risk stratification.

A novel approach to biomarker discovery in head and neck cancer using an autoantibody signature

Despite the dismal prognosis for patients with squamous cell carcinoma of the head and neck (SCCHN), there have been no novel treatments in over 40 years. Identification of novel tumor antigens in SCCHN will facilitate the identification of potential novel treatment targets. Tumor antigens are proteins selectively expressed by tumor cells and recognized by the host immune system. Phage-displayed tumor antigens were enriched by biopanning with normal and then SCCHN-specific serum. Ninety-six phage clones were sequenced for identification, and 21 clones were validated using Luminex. One of these proteins, L23, a novel tumor antigen in SCCHN, was validated as an oncogene. L23 is upregulated in SCCHN compared with normal keratinocytes. Knockdown of L23 inhibited proliferation, invasion and cell survival. Overexpression of L23 had the reverse effect. Overexpression of L23 in non malignant cells led to transformation. Injection of SCCHN cells with knockdown of L23 in mice, induced tumors that were significantly smaller than control tumors. In conclusion, the immunomic screen yielded a panel of antigens specific to SCCHN; one of these proteins, L23, is a novel oncogene in SCCHN.

Lymphocyte Cytosolic Protein 1 (LCP1) Is a Membrane Associated Molecular Target in Chronic Lymphocytic Leukemia and Is Activated in Microenvironment Signaling

Abstract 3866Chronic lymphocytic leukemia (CLL) is an incurable accumulation of malignant B-lymphocytes in peripheral circulation, which home to supportive leukemic microenvironments within the bone marrow, lymph nodes, and spleen. Membrane associated antigens are critical to the pathogenesis of CLL since they facilitate leukemic cell signaling, microenvironment homing, proliferation, and survival. Targeting CLL surface molecules and associated signaling patterns is a current focus of CLL therapeutic development with antibodies and vaccine-based approaches. Rituximab, ofatumumab, and alemtuzumab are widely used antibody-based therapeutics that are proven to be effective at targeting CLL membrane associated antigens. However, despite enhanced patient survival, targeting of non-obligate antigens such as CD20 ultimately leads to antibody resistance. In addition, the expression of CD52 across multiple healthy immune cells often produces unacceptable off-target toxicity. Targeting immunosurveilance antigens may provide a key to overcome these obstacles. A number of relevant tumor antigens such as p53, EGFR, WT1, BCR-Abl and CLL-specific ROR1 elicit robust autoimmune responses in cancer patients due to high levels of ectopic expression, high relative immunogenicity and obligate oncogenic signaling that forces expression despite autoimmune recognition. In many cases, autoantibody signatures were realized long after identification of the oncologic target antigens; however, the convergence of these two datasets implies that such signatures could be utilized to identify novel targets. To further explore this possibility, we interrogated anti-tumor humoral reactivity specifically directed against autologous CLL membrane antigens. Immunoreactive leads were identified by mass spectrometry. Potential membrane antigens were further confirmed using immunoblot and ELISA based techniques. Our analysis revealed Lymphocyte Cytosolic Protein 1 (LCP1), a membrane associated lymphocyte-specific target that is constitutively expressed on CLL and ectopically expressed in cancers of various histological subtypes. Subsequent confirmatory assays unveiled high frequency, robust, LCP1-specific IgG autoimmune responses in CLL patients despite a profound absence of reactivity to common viral and vaccine antigens, implying continued antigenic stimulation in an immunosuppressed host. LCP1 plays a critical role in B-cell biology by cross linking f-actin filaments, thereby solidifying cytoskeletal structures and providing a scaffold for CLL-critical signaling pathways such as PKC. In healthy B-cells phosphorylation of LCP1 at serine 5 is a key step in responding to CXCL12, a powerful lymph node and stromal cell chemokine. To further explore the role of LCP1 in CLL microenvironment recall signaling, we developed stable LCP1 knockdown and Ser-5 phosphomimetic CLL cell lines. Transwell assays confirmed that LCP1 activity contributed to the migration of CLL cells towards CXCL12. Our data reveals that LCP1 is a novel membrane associated target antigen in CLL with evidence of differential immune response as compared to common vaccine antigens. We also demonstrate that LCP1 plays a role in CLL microenvironment signaling. Future studies will focus on targeting specific moieties within LCP1 which are critical for its oncogenic signature. Disclosures:No relevant conflicts of interest to declare.

Tumor‐associated autoantibody signature for the early detection of gastric cancer

Autoantibodies against tumor-associated antigens are very attractive biomarkers for the development of noninvasive serological tests for the early detection of cancer because of their specificity and stability in the sera. In our study, we applied T7 phage display-based serological analysis of recombinant cDNA expression libraries technique to identify a representative set of antigens eliciting humoral responses in patients with gastric cancer (GC), produced phage-antigen microarrays and exploited them for the survey of autoantibody repertoire in patients with GC and inflammatory diseases. We developed procedures for data normalization and cutoff determination to define sero-positive signals and ranked them by the signal intensity and frequency of reactivity. To identify autoantibodies with the highest diagnostic value, a 1,150-feature microarray was tested with sera from 100 patients with GC and 100 cancer-free controls, and then the top-ranked 86 antigens were used for the production of focused array that was tested with an independent validation set comprising serum samples from 235 patients with GC, 154 patients with peptic ulcer and gastritis and 213 healthy controls. The receiver operating characteristic curve analysis showed that 45-autoantibody signature could discriminate GC and healthy controls with area under the curve (AUC) of 0.79 (59% sensitivity and 90% specificity), GC and peptic ulcer with AUC of 0.76 and GC and gastritis with AUC of 0.64. Moreover, it could detect early GC with equal sensitivity than advanced GC. Interestingly, the autoantibody production did not correlate with histological type, H. pylori status, grade, localization and size of the primary tumor, whereas it appeared to be associated with the metastatic disease.

880 Diagnostic and Prognostic Relevance of Tumour-associated Autoantibody Signatures in Gastric Cancer

880 Diagnostic and Prognostic Relevance of Tumour-associated Autoantibody Signatures in Gastric Cancer

Autoantibody profiling of benign and malignant thyroid tumors and design of a prototype diagnostic array

Currently the “gold standard” in diagnostics of thyroid tumors is a fine-needle aspiration cytology (FNAC). However, FNAC cannot discriminate between benign and malignant thyroid tumors in 15 to 30% of observations. In order to develop an additional tool for differential diagnostics of thyroid tumors we evaluated the diagnostic performance of 3-antigen serum autoantibody signature in groups of benign ( n = 22) and malignant ( n = 26) thyroid tumors using a dot-blot ELISA-based analysis The sensitivity and specificity of resultant array were estimated to be 55–60% and 95–100%, respectively ( p < 0.001 according to one-sided Fisher Exact Test). Thus, we created a prototype antigen array for differential diagnostics of thyroid tumors which can be regarded as a platform for design of more complicated panel, highly sensitive in thyroid cancer detection, which can significantly improve the accuracy of preoperative diagnosis of thyroid cancer.

Abstract 3643: Early detection of cancer in the general population - a blinded case control study of p53 auto-antibodies in colorectal cancer in UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS)

Abstract Purpose: Recent reports from cancer screening trials in high-risk populations suggest that autoantibodies are present prior to clinical diagnosis. However there are few data on the role of autoantibody signatures in cancer screening in the general population. Methods: Informative p53 peptides were identified on an autoantibody microarray with 15-mer overlapping peptides covering the complete p53 sequence using sera from patients with colorectal cancer. The selected peptides were evaluated in a blinded case control study using stored serum from the multimodal arm of UKCTOCS where women gave annual blood samples. Cases were postmenopausal women who developed colorectal cancer following recruitment, with 2 or more serum samples preceding diagnosis. Controls were age-matched women with no history of cancer. Results: The 50,640 women randomised to the multimodal group were followed up for a median of 6.8 (inter-quartile range 5.9-8.4) years. Colorectal cancer notification was received in 101 women with serial samples of whom 97 (277 samples) had given consent for secondary studies. They were matched 1:1 with 97 controls (276 serial samples). The four most informative peptides identified 25.8% of colorectal cancer patients with a specificity of 95%. The median lead time was 1.4 (range 0.12-3.8) years prior to clinical diagnosis. Conclusion: Our findings suggest that in the general population, autoantibody signatures are present during preclinical disease and may be of value in cancer screening. In colorectal cancer screening in particular, where the current need is to improve compliance, it suggests that p53 autoantibodies may contribute towards risk stratification. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3643. doi:1538-7445.AM2012-3643

Serum Autoantibody Signature of Ductal Carcinoma In Situ Progression to Invasive Breast Cancer

The identification of markers associated with progression to invasive breast cancer (IBC) is a major factor that can guide physicians in the initial therapeutic decision and the management of ductal carcinoma in situ (DCIS). We examined autoantibody targets in 20 DCIS and 20 IBC patients using protein microarrays and identified humoral responses that can be used to distinguish the two groups. The five most differentially targeted antigens were selected to generate an autoantibody signature for the in situ to invasive breast cancer transition. This signature was next tested on 120 independent samples (61 DCIS and 59 IBC) using specific ELISA assays. The prognosis value of the autoantibody signature was finally evaluated in a cohort of DCIS patients followed for 5 years. A set of five autoantibody targets (RBP-Jκ, HMGN1, PSRC1, CIRBP, and ECHDC1) with the highest differential signal intensity found in the protein microarrays experiment was used to establish an autoantibody signature of the DCIS to IBC transition. Using ELISA, this signature significantly discriminated DCIS from IBC [area under the ROC curve (AUC) = 0.794, 95% confidence interval (CI): 0.674-0.877]. Interestingly, our panel could highly distinguish low-grade DCIS from high-grade DCIS exhibiting an AUC of 0.749 (95% CI: 0.581-0.866). Finally, using a Kaplan-Meier analysis, the autoantibody signature could significantly divide the DCIS patients into a poor prognosis group and a good prognosis group (P = 0.01). These results indicate the potential of autoantibody detection as a new prognostic test with possible clinical implications for the management of DCIS.

Is there a general autoantibody signature for cancer?

BackgroundThere is longstanding evidence for the diagnostic potential of single autoantibodies for cancer and other diseases and more recently for the potential of complex autoantibody signatures. Here we address the question whether cancer specific signatures exist. MethodsWe analysed our autoantibody screening data both newly and previously generated using a single array platform with 1827 identified immunogenic clones. These clones were tested for their reactivity against a total of 428 human sera including 191 sera of patients with different cancer entities, 60 sera of healthy individuals and 177 sera of patients with non-cancer diseases by using bioinformatics approaches. ResultsPrincipal Component Analysis and hierarchical clustering revealed significant differences between the three cohorts. Evaluating the autoantibody reactivities in the three groups using Support Vector Machines, we were able to separate cancer sera from normal sera with an accuracy of 94.08%. A pathway analysis that was based on antigens with an increased reactivity in patients’ sera as compared to controls indicated glycolysis as central pathway. The separation between cancer and non-cancer disease sera was possible with an accuracy of only 69.58%, which is still significantly higher than by random classification. ConclusionAs for single autoantigens, we show that proteins that are frequently reactive with cancer sera are also frequently reactive with non-cancer sera. While these results underline the potential of autoantibody signatures for cancer diagnosis, they also caution to premature claim specificity of a signature.

Autoantibody Signature Differentiates Wilms Tumor Patients from Neuroblastoma Patients

Several studies report autoantibody signatures in cancer. The majority of these studies analyzed adult tumors and compared the seroreactivity pattern of tumor patients with the pattern in healthy controls. Here, we compared the autoimmune response in patients with neuroblastoma and patients with Wilms tumor representing two different childhood tumors. We were able to differentiate untreated neuroblastoma patients from untreated Wilms tumor patients with an accuracy of 86.8%, a sensitivity of 87.0% and a specificity of 86.7%. The separation of treated neuroblastoma patients from treated Wilms tumor patients' yielded comparable results with an accuracy of 83.8%. We furthermore identified the antigens that contribute most to the differentiation between both tumor types. The analysis of these antigens revealed that neuroblastoma was considerably more immunogenic than Wilms tumor. The reported antigens have not been found to be relevant for comparative analyses between other tumors and controls. In summary, neuroblastoma appears as a highly immunogenic tumor as demonstrated by the extended number of antigens that separate this tumor from Wilms tumor.

Autoantibody signatures as biomarkers to distinguish prostate cancer from benign prostatic hyperplasia in patients with increased serum prostate specific antigen

BackgroundSerum prostate specific antigen (PSA) concentrations lack the specificity to differentiate prostate cancer from benign prostate hyperplasia (BPH), resulting in unnecessary biopsies. We identified 5 autoantibody signatures to specific cancer targets which might be able to differentiate prostate cancer from BPH in patients with increased serum PSA. MethodsTo identify autoantibody signatures as biomarkers, a native antigen reverse capture microarray platform was used. Briefly, well-characterized monoclonal antibodies were arrayed onto nanoparticle slides to capture native antigens from prostate cancer cells. Prostate cancer patient serum samples (n=41) and BPH patient samples (collected starting at the time of initial diagnosis) with a mean follow-up of 6.56y without the diagnosis of cancer (n=39) were obtained. One hundred micrograms of IgGs were purified and labeled with a Cy3 dye and incubated on the arrays. The arrays were scanned for fluorescence and the intensity was quantified. Receiver operating characteristic curves were produced and the area under the curve (AUC) was determined. ResultsUsing our microarray platform, we identified autoantibody signatures capable of distinguishing between prostate cancer and BPH. The top 5 autoantibody signatures were TARDBP, TLN1, PARK7, LEDGF/PSIP1, and CALD1. Combining these signatures resulted in an AUC of 0.95 (sensitivity of 95% at 80% specificity) compared to AUC of 0.5 for serum concentration PSA (sensitivity of 12.2% at 80% specificity). ConclusionOur preliminary results showed that we were able to identify specific autoantibody signatures that can differentiate prostate cancer from BPH, and may result in the reduction of unnecessary biopsies in patients with increased serum PSA.

Multicenter study identified molecular blood‐born protein signatures for Wilms Tumor

Wilms Tumor (WT) is the most common renal childhood tumor. Recently, we reported a cDNA microarray expression pattern that varied between WTs with different risk histology. Since the Societé Internationale d'Oncologie Pédiatrique (SIOP) in Europe initiates treatment without a histological confirmation, it is important to identify blood-born markers that indicate WT development. In a multicenter study, we established an autoantibody signature by using an array with 1,827 recombinant E. coli clones. This array was screened with sera of patients with WT recruited by SIOP or the Children's Oncology Group (COG). We report an extended number of antigens that are reactive with autoantibodies present in sera from patients with WT. We established an autoantibody signature that separates untreated patients with WT recruited in SIOP from non-WT controls with a specificity of 0.83 and a sensitivity of 0.82 at standard deviations of 0.02 and 0.04, respectively. Likewise, patients recruited in the COG in the United States were separated from the controls with an accuracy of 0.83 at a standard deviation of 0.02. Proteins that were most significant include zinc finger proteins (e.g., ZFP 346), ribosomal proteins and the protein fascin that has been associated with various types of cancer including renal cell carcinoma. Our study provides first evidence for autoantibody signatures for WTs and suggests that these may be most informative before chemotherapy. We present the first multicenter study of autoantibody signatures in patients with WT. We established an autoantibody signature that separates patients with WT from controls.

Protein Array Diagnostics for Guiding Therapy in Rheumatoid Arthritis

Early diagnosis and effective management of rheumatoid arthritis (RA) are pivotal, given the progressive, chronic, inflammatory, multi-systemic nature of the disease. Currently, proper initiation of adequate, individually tailored interventions in RA is delayed by the difficulty of early diagnosis and the limitations of disease activity and therapeutic response assessment tools. This is a significant challenge to rheumatologists, further complicated by the dynamic and progressively evolving autoimmune nature of RA, which is characterized by several immune mediators in a complex network that regulates the perpetuation of inflammation. Protein arrays constitute the most advanced current technology that can provide a comprehensive parallel analysis of this diverse network in RA, providing an individualized insight into immune status and host immune response. The last few years have seen significant transitions in the field of protein arrays, demonstrated by a technologic shift from the bench to the bedside, paving the way for the medical and scientific community to deliver patient-specific assessments and personalized management. Screening of protein arrays with sera or tissues from patients with RA enables the probing of immune responses and the identification of autoantibody signatures that can be used for the diagnosis and therapeutic management of patients. This article reviews the technology and the applications for protein arrays in the diagnosis and prognosis of RA. Clinical assessment tools could be derived from protein arrays, which may provide a means to continually track patients, allowing better evaluation of intervention strategies on a patient-specific basis and identification of diagnostic and disease activity biomarkers that could be used to guide optimal therapy in RA.

Autoantibody signatures: progress and perspectives for early cancer detection

Becoming invasive is a crucial step in cancer development, and the early spread of tumour cells is usually undetected by current imaging technologies. In patients with cancer and no signs of overt metastases, sensitive methods have been developed to identify circulating autoantibodies and their antigen counterparts in several cancers. These technologies are often based on proteomic approaches, and recent advances in protein and antibody microarrays have greatly facilitated the discovery of new antibody biomarkers in sera from cancer patients. Interestingly, in a clinical application setting, combinations of multiple autoantibody reactivities into panel assays have recently been proposed as relevant screening tests and validated in several independent trials. In addition, autoantibody signatures seem to be particularly relevant for early detection of cancer in high-risk cancer patients. In this review, we highlight the concept that immunogenic epitopes associated with the humoural response and key pathogenic pathways elicit serum autoantibodies that can be considered as relevant cancer biomarkers. We outline the proteomic strategies employed to identify and validate their use in clinical practice for cancer screening and diagnosis. We particularly emphasize the clinical utility of autoantibody signatures in several cancers. Finally, we discuss the challenges remaining for clinical validation.

Development of Autoantibody Signatures as Biomarkers for Early Detection of Colorectal Carcinoma

To select autoantibody signatures for early detection of colorectal cancer (CRC). A phage cDNA expression library was constructed with fresh tumors from 30 CRC patients and biopanned by using serum pools of 20 CRC patients and 20 healthy controls. A classifier was discovered in the training set of 30 CRC patients at stages I and II and 30 matched healthy controls and then blindly validated in an independent set of 60 CRC patients, 60 healthy controls, 52 polyps patients, and 30 autoimmune diseases patients. Expression of proteins was examined by using immunohistochemistry. Five-phage peptide clones showing higher discriminatory power than others in training set were selected for validation. The five-phage peptide classifier was able to discriminate between early CRC patients and healthy controls, with sensitivities of 90.0% to 92.7% and specificities of 91.7% to 93.3%. In those with serum carcinoembryonic antigen less than 5 ng/mL, the classifier was efficient in discriminating CRC from healthy controls, with an area under the curve of 0.975. The classifier was able to discriminate all of the 9 patients with serrated adenoma from healthy controls. Thirteen (43.3%) of the patients with autoimmune diseases were misclassified. Of the five phage peptides, one encoded a peptide identical to immunoglobulin G (IgG) heavy-chain constant region. IgG immunostaining was stronger in mesenchymal cells than in cancer cells in the tumors and was apparent in serrated adenoma. The five-phage peptide classifier stands out as promising early diagnostic biomarkers for CRC, but it is unsuitable for discriminating CRC from autoimmune diseases. Truncated IgGs generated from the tumors might be novel CRC-associated antigens.

Autoanticorps et diagnostic précoce des cancers

It is now well established that an immune response to cancer is elicited in humans, as demonstrated in part by the identification of autoantibodies against a number of tumor-associated antigens in sera from patients with different types of cancer. During these past few years, proteomic approaches have been developed to identify tumor-associated antigens and their cognate autoantibodies. Detection of a panel of serum autoantibodies has thus been proposed as a new method for early cancer diagnosis. Early detection seems to be particularly adequate in high-risk populations, such as heavy smokers for lung cancer or in women with high mammographic density for breast cancer. In this review, we highlight the features of serum autoantibody biomarkers and outline the proteomic strategies employed to identify and validate their use in clinical practice for cancer screening and diagnosis. We particularly emphasize the clinical utility of autoantibody signatures, using the examples of lung and breast cancer. Finally, we discuss the challenges remaining for clinical validation.