Patent Application
20220214344
The present invention relates to methods for detecting pancreatic cancer, and biomarkers and arrays for use in the same.
Pancreatic ductal adenocarcinoma, or pancreatic cancer (PC) is the 4th most common cancer-related cause of death, resulting in almost as many deaths as in breast cancer in the United States, despite a 10 times lower incidence [1]. The poor prognosis is mostly due to the inability to detect PC at an early stage, even though data supports that it takes more than five years from tumor initiation until the acquisition of metastatic ability [2], clearly demonstrating a window of opportunity for early detection if markers were available. Today, the cancer is often detected at advanced disease progression, with tumors that are inoperable and already have metastasized [1, 3]. However, even if the five-year survival of large resected tumors is only 10-20% [4, 5], it increases to 30-60% if tumors <20 mmm can be resected [6, 7], and to >75% if the size at resection is <10 mm [8]. The late detection is due to unspecific clinical symptoms as well as lack of sensitive technologies and markers for early diagnosis. Interestingly, studies suggest that pancreatic tumors could be resectable as early as six months prior to clinical diagnosis at an asymptomatic stage [9, 10].
The so far most evaluated marker for PC, CA19-9, suffers from poor specificity, with elevated levels also in pancreatitis and other cancers, and a complete absence in Lewis a and b negative tumors. Consequently, the use of CA19-9 for pancreatic cancer screening has been discouraged [11]. Despite many efforts, no other single biomarkers have been shown to outperform CA19-9, and in recent years the field has been moving towards multiplexed marker panels for increased sensitivity and specificity [12]. Panels have primarily consisted of high abundant blood proteins, frequently acute-phase reactants (e.g. CRP and SAA), known tumor markers (e.g. CA242, CA125 and CEA), adhesion molecules (e.g. ICAM-1 and ADCAM), proteins involved in extracellular matrix degradation (e.g. MMPs and TIMP1), lipoproteins (e.g. Apo-C1, Apo-A2), and several others, most often in combination with CA19-9 [15-20]. Despite reports of high sensitivity for PC versus healthy controls or benign pancreatic conditions, none of these panels have yet been validated for clinical use.
Besides the markers already mentioned, several immunoregulatory proteins may be of interest as tumor biomarkers, as the association between cancer and inflammation keeps unraveling [21]. Considering the systemic effect as well as the multitude in functions of many of the immunoregulatory proteins, it is generally considered that small panels of 2 to 5 markers will not be sufficiently specific for pancreatic cancer, particularly when trying to discriminate pancreatic cancer from pancreatitis and other conditions that present with similar symptoms. However, previous studies have shown that an increased number of these analytes (25) may yield highly disease specific immunosignatures reflecting the systemic response to disease [22-24].
Nevertheless, analysis of the immunoregulatory proteome is associated with several challenges. First, the serum concentration of the proteins of interest displays a vast dynamic range, from high microgram to low picogram per mL, which complicates their simultaneous detection using conventional proteomic methodologies [25, 26]. Second, there seems to be a consensus in that promising cancer markers are more likely to be found among the most low abundant, often low-molecular weight proteins [27, 28]. Third, the disease-associated changes in serum levels of these low abundant analytes is expected to be small, and thus a significant number of clinical samples will be needed for adequate statistics [29]. For these purposes, we have designed highly multiplexed recombinant antibody microarrays with close to 300 scFv antibodies targeting mainly immunoregulatory proteins [30]. With these arrays, protein expression can be measured in hundreds of samples in a highly reproducible and high-throughput manner.
In this multicenter study, 338 individual serum samples from patients with pancreatic cancer, benign pancreatic disease, as well as normal controls, were analyzed on our in-house designed antibody microarrays. To define the most discriminative marker signatures, we applied an iterative backward elimination procedure, based on support vector machine analysis and designed to predict the optimal combination of antibodies [31]. To this end, 25-plex immunosignatures for discriminating PC from benign and healthy controls were identified in training sets, prevalidated in independent test sets, and compared to signatures derived from differential protein expression analysis. In addition, protein profiling could be applied to stratify serum samples based on the original location of the tumor in the pancreas, which to the best of our knowledge has not previously been done with proteomics. Together, these findings add important information to the proteome puzzle of pancreatic cancer, which may in the end result in multiplexed biomarkers providing benefit for thousands of patients.
Accordingly, a first aspect of the invention provides a method for detecting pancreatic cancer in an individual comprising or consisting of the steps of:
wherein the expression in the test sample of the one or more biomarker selected from the group defined in Table A (i), (ii) or (iii) is indicative of the presence of pancreatic cancer.
By “sample to be tested”, “test sample” or “control sample” we include a tissue or fluid sample taken or derived from an individual. Preferably the sample to be tested is provided from a mammal. The mammal may be any domestic or farm animal. Preferably, the mammal is a rat, mouse, guinea pig, cat, dog, horse or a primate. Most preferably, the mammal is human. Preferably the sample is a cell or tissue sample (or derivative thereof) comprising or consisting of plasma, plasma cells, serum, tissue cells or equally preferred, protein or nucleic acid derived from a cell or tissue sample. Preferably test and control samples are derived from the same species.
In an alternative or additional embodiment the tissue sample is pancreatic tissue. In an alternative or additional embodiment, the cell sample is a sample of pancreatic cells.
By “expression” we mean the level or amount of a gene product such as mRNA or protein.
Methods of detecting and/or measuring the concentration of protein and/or nucleic acid are well known to those skilled in the art, see for example Sambrook and Russell, 2001, Cold Spring Harbor Laboratory Press.
By “biomarker” we mean a naturally-occurring biological molecule, or component or fragment thereof, the measurement of which can provide information useful in the prognosis of pancreatic cancer. For example, the biomarker may be a naturally-occurring protein or carbohydrate moiety, or an antigenic component or fragment thereof.
In an alternative or additional embodiment, the method comprises or consists of steps (a) and (b) and the further steps of:
wherein the presence of pancreatic cancer is identified in the event that the expression in the test sample of the one or more biomarkers measured in step (b) is different from the expression in the control sample of the one or more biomarkers measured in step (d).
The one or more control sample may be from a healthy individual (i.e., an individual unaffiliated by any disease or condition), an individual afflicted with a non-pancreatic disease or condition or an individual afflicted with a benign pancreatic disease or condition (for example, acute or chronic pancreatitis).
In another embodiment, the method comprises or consists of steps (a) and (b) and, optionally, steps (c) and (d) and the additional steps of:
wherein the presence of pancreatic cancer is identified in the event that the expression in the test sample of the one or more biomarkers measured in step (b) corresponds to the expression in the control sample of the one or more biomarkers measured in step (f).
In an alternative or additional embodiment, a standard or reference value is used instead of, or in addition, to the one or more positive or negative control. Hence, the standard or references value(s) may be determined in separate procedures from the test value(s).
In an alternative or additional embodiment, the method is for determining the presence of pancreatic cancer originating from (i) the head of the pancreas or (ii) the body or tail of the pancreas. In this embodiment, step (e) may comprise (i) providing one or more control sample from an individual afflicted with pancreatic cancer originating from the head of the pancreas and/or (ii) providing one or more control sample from an individual afflicted with pancreatic cancer originating from the body or tail of the pancreas.
In this embodiment, the presence of pancreatic cancer originating from head of the pancreas is identified in the event that the expression in the (e)(i) test sample (where present) of the one or more biomarkers measured in step (b) corresponds to the expression in the control sample of the one or more biomarkers measured in step (f) and/or the expression in the (e)(ii) test sample (where present) of the one or more biomarkers measured in step (b) is different from the expression in the control sample of the one or more biomarkers measured in step (f).
In this embodiment, the presence of pancreatic cancer originating from the body or tail of the pancreas is identified in the event that the expression in the (e)(i) test sample (where present) of the one or more biomarkers measured in step (b) is different from the expression in the control sample of the one or more biomarkers measured in step (f) and/or the expression in the (e)(ii) test sample (where present) of the one or more biomarkers measured in step (b) corresponds to the expression in the control sample of the one or more biomarkers measured in step (f).
By “corresponds to the expression in the control sample” we include that the expression of the one or more biomarkers in the sample to be tested is the same as or similar to the expression of the one or more biomarkers of the positive control sample. Preferably the expression of the one or more biomarkers in the sample to be tested is identical to the expression of the one or more biomarkers of the positive control sample.
Differential expression (up-regulation or down regulation) of biomarkers, or lack thereof, can be determined by any suitable means known to a skilled person. Differential expression is determined to a p value of a least less than 0.05 (p=<0.05), for example, at least <0.04, <0.03, <0.02, <0.01, <0.009, <0.005, <0.001, <0.0001, <0.00001 or at least <0.000001. Preferably, differential expression is determined using a support vector machine (SVM). Preferably, the SVM is an SVM as described below. Most preferably, the SVM is the SVM described in Table B, below.
It will be appreciated by persons skilled in the art that differential expression may relate to a single biomarker or to multiple biomarkers considered in combination (i.e. as a biomarker signature). Thus, a p value may be associated with a single biomarker or with a group of biomarkers. Indeed, proteins having a differential expression p value of greater than 0.05 when considered individually may nevertheless still be useful as biomarkers in accordance with the invention when their expression levels are considered in combination with one or more other biomarkers.
As exemplified in the accompanying examples, the expression of certain proteins in a tissue, blood, serum or plasma test sample may be indicative of pancreatic cancer in an individual. For example, the relative expression of certain serum proteins in a single test sample may be indicative of the presence of pancreatic cancer in an individual.
Step (b) may comprise or consist of measuring the expression of 1 or more biomarker from the biomarkers listed in Table A(i). Step (b) may comprise or consist of measuring the expression of each of the biomarkers listed in Table A(i), for example at least 2 of the biomarkers listed in Table A(i). Hence, step (b) may comprise or consist of measuring the expression of all of the biomarkers listed in Table A(i).
Step (b) may comprise or consist of measuring the expression of 1 or more biomarker from the biomarkers listed in Table A(ii), for example at least 2, 3, 4, 5, 6, 7, 8 or 9 of the biomarkers listed in Table A(ii). Hence, step (b) may comprise or consist of measuring the expression of all of the biomarkers listed in Table A(ii).
Step (b) may comprise or consist of measuring the expression of 1 or more biomarker from the biomarkers listed in Table A(iii), for example at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17 of the biomarkers listed in Table A(iii). Hence, step (b) may comprise or consist of measuring the expression of all of the biomarkers listed in Table A(iii).
Step (b) may comprise or consist of measuring the expression of 1 or more biomarker from the biomarkers listed in Table A(iv), for example at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 or 22, 23 or 24 of the biomarkers listed in Table A(iv). Hence, step (b) may comprise or consist of measuring the expression of all of the biomarkers listed in Table A(iv).
Step (b) may comprise or consist of measuring the expression of 1 or more biomarker from the biomarkers listed in Table A(v), for example at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55 or 56 of the biomarkers listed in Table A(v). Hence, step (b) may comprise or consist of measuring the expression of all of the biomarkers listed in Table A(v).
Step (b) may comprise or consist of measuring the expression of 1 or more biomarker from the biomarkers listed in Table A(vi). Hence, step (b) may comprises or consists of measuring the expression of all of the biomarkers listed in Table A(vi).
Step (b) may comprise or consist of measuring the expression of 1 or more biomarker from the biomarkers listed in Table A, for example at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109 or 110 of the biomarkers listed in Table A. Hence, step (b) may comprise or consist of measuring the expression of all of the biomarkers listed in Table A.
Where the method is for determining the presence of pancreatic adenocarcinoma step (b) preferably comprises or consists of measuring the expression of:
Where the method is for determining the presence of pancreatic adenocarcinoma originating from (i) the head of the pancreas or (ii) the body or tail of the pancreas step (b) preferably comprises or consists of measuring the expression of:
When referring to a “normal” disease state we include individuals not afflicted with chronic pancreatitis (ChP) or acute inflammatory pancreatitis (AIP). Preferably the individuals are not afflicted with any pancreatic disease or disorder. Most preferably, the individuals are healthy individuals, i.e., they are not afflicted with any disease or disorder.
In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Transcription factor SOX-11. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Integrin alpha-10. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of EDFR (SEQ ID NO: 3). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of EPFR (SEQ ID NO: 4). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of LSADHR (SEQ ID NO: 5). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of SEAHLR (SEQ ID NO: 6). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of AQQHQWDGLLSYQDSLS (SEQ ID NO: 7). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of WTRNSNMNYWLIIRL (SEQ ID NO: 8). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of WDSR (SEQ ID NO: 9). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of DFAEDK (SEQ ID NO: 10). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of FASN protein. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of GAK protein. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of HADH2 protein. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of LNVWGK (SEQ ID NO: 11). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of LTEFAK (SEQ ID NO: 12). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of LYEIAR (SEQ ID NO: 13). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Megakaryocyte-associated tyrosine-protein kinase. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Oxysterol-binding protein-related protein 3. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of QEASFK (SEQ ID NO: 14). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of SSAYSR (SEQ ID NO: 15). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of QEASFK (SEQ ID NO: 14). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of TEEQLK (SEQ ID NO: 16). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of TLYVGK (SEQ ID NO: 17). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of FLLMQYGGMDEHAR (SEQ ID NO: 18). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of GIVKYLYEDEG (SEQ ID NO: 19). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of GIVKYLYEDEG (SEQ ID NO: 19). In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Tumor necrosis factor receptor superfamily member 3. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Tyrosine-protein kinase SYK. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Angiomotin. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of C—C motif chemokine 2. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of C—C motif chemokine 5. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of CD40 ligand. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Glucagon-like peptide-1. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Immunoglobilin M. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-1 alpha. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-1 receptor antagonist protein. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-11. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-12. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-16. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-18. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-2. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-3. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-4. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-6. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-7. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-9. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Lewis x. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Lymphotoxin-alpha. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Transforming growth factor beta-1. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Vascular endothelial growth factor. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Visual system homeobox 2. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of HLA-DR/DP. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Apolipoprotein A1. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Apolipoprotein A4. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Apolipoprotein B-100. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of ATP synthase subunit beta, mitochondrial. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Beta-galactosidase. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Cathepsin W. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of C—C motif chemokine 13. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of C—C motif chemokine 7. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of CD40 protein. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Complement C1q. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Complement C1s. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Complement C3. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Complement C4. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Complement C5. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Complement factor B. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Cyclin-dependent kinase 2. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Cystatin-C. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Eotaxin. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Epidermal growth factor receptor. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Glucagon-like peptide 1 receptor. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Granulocyte-macrophage colony-stimulating factor. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Integrin alpha-11. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Intercellular adhesion molecule 1. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interferon gamma. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-1 beta. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-10. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-13. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-5. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Interleukin-8. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Keratin, type I cytoskeletal 19. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Leptin. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Lumican. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Mitogen-activated protein kinase 1. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Mitogen-activated protein kinase 8. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Mucin-1. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Myomesin-2. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Osteopontin. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Phosphatidylinositol 3-kinase regulatory subunit alpha. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Plasma protease C1 inhibitor. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Properdin. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Prostate-specific antigen. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Receptor tyrosine-protein kinase erbB-2. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Regulator of nonsense transcripts 3B. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Ribosomal protein S6 kinase alpha-2. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Sialyl Lewis x. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Signal-transducing adaptor protein 2. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of SUMO-conjugating enzyme UBC9. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of TBC1 domain family member 9. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Transmembrane peptide. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Tumor necrosis factor alpha. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Tumor necrosis factor receptor superfamily member 14. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Tyrosine-protein kinase BTK. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Tyrosine-protein kinase JAK3. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Tyrosine-protein phosphatase non-receptor type 1. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Ubiquitin carboxyl-terminal hydrolase isozyme L5. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of Ubiquitin-conjugating enzyme E2 C. In an alternative or additional embodiment, step (b) comprises or consists of measuring the expression of FIQTDK (SEQ ID NO: 20).
In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Transcription factor SOX-11. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Integrin alpha-10. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of EDFR (SEQ ID NO: 3). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of EPFR (SEQ ID NO: 4). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of LSADHR (SEQ ID NO: 5). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of SEAHLR (SEQ ID NO: 6). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of AQQHQWDGLLSYQDSLS (SEQ ID NO: 7). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of WTRNSNMNYWLIIRL (SEQ ID NO: 8). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of WDSR (SEQ ID NO: 9). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of DFAEDK (SEQ ID NO: 10). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of FASN protein. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of GAK protein. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of HADH2 protein. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of LNVWGK (SEQ ID NO: 11). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of LTEFAK (SEQ ID NO: 12). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of LYEIAR (SEQ ID NO: 13). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Megakaryocyte-associated tyrosine-protein kinase. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Oxysterol-binding protein-related protein 3. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of QEASFK (SEQ ID NO: 14). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of SSAYSR (SEQ ID NO: 15). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of QEASFK (SEQ ID NO: 14). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of TEEQLK (SEQ ID NO: 16). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of TLYVGK (SEQ ID NO: 17). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of FLLMQYGGMDEHAR (SEQ ID NO: 18). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of GIVKYLYEDEG (SEQ ID NO: 19). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of GIVKYLYEDEG (SEQ ID NO: 19). In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Tumor necrosis factor receptor superfamily member 3. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Tyrosine-protein kinase SYK. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Angiomotin. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of C—C motif chemokine 2. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of C—C motif chemokine 5. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of CD40 ligand. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Glucagon-like peptide-1. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Immunoglobilin M. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-1 alpha. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-1 receptor antagonist protein. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-11. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-12. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-16. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-18. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-2. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-3. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-4. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-6. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-7. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-9. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Lewis x. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Lymphotoxin-alpha. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Transforming growth factor beta-1. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Vascular endothelial growth factor. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Visual system homeobox 2. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of HLA-DR/DP. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Apolipoprotein A1. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Apolipoprotein A4. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Apolipoprotein B-100. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of ATP synthase subunit beta, mitochondrial. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Beta-galactosidase. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Cathepsin W. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of C—C motif chemokine 13. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of C—C motif chemokine 7. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of CD40 protein. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Complement C1q. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Complement C1s. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Complement C3. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Complement C4. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Complement C5. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Complement factor B. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Cyclin-dependent kinase 2. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Cystatin-C. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Eotaxin. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Epidermal growth factor receptor. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Glucagon-like peptide 1 receptor. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Granulocyte-macrophage colony-stimulating factor. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Integrin alpha-11. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Intercellular adhesion molecule 1. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interferon gamma. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-1 beta. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-10. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-13. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-5. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Interleukin-8. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Keratin, type I cytoskeletal 19. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Leptin. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Lumican. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Mitogen-activated protein kinase 1. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Mitogen-activated protein kinase 8. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Mucin-1. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Myomesin-2. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Osteopontin. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Phosphatidylinositol 3-kinase regulatory subunit alpha. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Plasma protease C1 inhibitor. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Properdin. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Prostate-specific antigen. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Receptor tyrosine-protein kinase erbB-2. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Regulator of nonsense transcripts 3B. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Ribosomal protein S6 kinase alpha-2. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Sialyl Lewis x. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Signal-transducing adaptor protein 2. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of SUMO-conjugating enzyme UBC9. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of TBC1 domain family member 9. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Transmembrane peptide. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Tumor necrosis factor alpha. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Tumor necrosis factor receptor superfamily member 14. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Tyrosine-protein kinase BTK. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Tyrosine-protein kinase JAK3. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Tyrosine-protein phosphatase non-receptor type 1. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Ubiquitin carboxyl-terminal hydrolase isozyme L5. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of Ubiquitin-conjugating enzyme E2 C. In an alternative or additional embodiment, step (b) does not comprise or consist of measuring the expression of FIQTDK (SEQ ID NO: 20).
By “transmembrane peptide” or “TM peptide” we mean a peptide derived from a 10TM protein, to which the scFv antibody construct of SEQ ID NO: 1 below has specificity (wherein the CDR sequences are indicated by bold, italicised text):
KGLEW
FTISRDNSKNTLYLQMNSLRAEDTAVYY
WYQQLPGTAPKLLIY
GVPDR
FGGGTKLTVL
Hence, this scFv may be used or any antibody, or antigen binding fragment thereof, that competes with this scFv for binding to the 10TM protein. For example, the antibody, or antigen binding fragment thereof, may comprise the same CDRs as present in SEQ ID NO:1.
It will be appreciated by persons skilled in the art that such an antibody may be produced with an affinity tag (e.g. at the C-terminus) for purification purposes. For example, an affinity tag of SEQ ID NO: 2 below may be utilised:
In an alternative or additional embodiment, the one or more biomarker measured in step (b) comprise or consist of one or more biomarker selected from the group consisting of:
In this embodiment, the method may be for discriminating between pancreatic cancer (PC), and non-pancreatic cancer (NC) and/or benign pancreatic conditions (BC).
In an alternative or additional embodiment the one or more biomarker measured in step (b) comprise or consist of one or more biomarker selected from the group consisting of:
In this embodiment, the method may be for discriminating between pancreatic cancer (PC), and non-pancreatic cancer (NC).
In an alternative or additional embodiment, the one or more biomarker measured in step (b) comprise or consist of one or more biomarker selected from the group consisting of:
In this embodiment, the method may be for discriminating between pancreatic cancer (PC), and benign pancreatic conditions (BC).
In an alternative or additional embodiment, the method comprises or consists of steps (a) and (b), optionally, steps (c) and (d), optionally, steps (e) and (f), and the additional step of:
In an alternative or additional embodiment is based on the trends (up- or down-regulation) identified in Table 2.
In an alternative or additional embodiment step (b) and, where present, steps (d) and (f) are performed by contacting the sample to be tested with binding moiety for the one or more biomarker measured in step (b), for example, as first binding moiety as defined below.
In an alternative or additional embodiment, the method comprises or consists of the use of biomarkers listed in Table 3.
Generally, diagnosis is made with an ROC AUC of at least 0.55, for example with an ROC AUC of at least, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 0.96, 0.97, 0.98, 0.99 or with an ROC AUC of 1.00. Preferably, diagnosis is made with an ROC AUC of at least 0.85, and most preferably with an ROC AUC of 1.
Typically, diagnosis is performed using a support vector machine (SVM), such as those available from cran.r-project.org/web/packages/e1071/index.html (e.g. e1071 1.5-24). However, any other suitable means may also be used.
Support vector machines (SVMs) are a set of related supervised learning methods used for classification and regression. Given a set of training examples, each marked as belonging to one of two categories, an SVM training algorithm builds a model that predicts whether a new example falls into one category or the other. Intuitively, an SVM model is a representation of the examples as points in space, mapped so that the examples of the separate categories are divided by a clear gap that is as wide as possible. New examples are then mapped into that same space and predicted to belong to a category based on which side of the gap they fall on.
More formally, a support vector machine constructs a hyperplane or set of hyperplanes in a high or infinite dimensional space, which can be used for classification, regression or other tasks. Intuitively, a good separation is achieved by the hyperplane that has the largest distance to the nearest training datapoints of any class (so-called functional margin), since in general the larger the margin the lower the generalization error of the classifier. For more information on SVMs, see for example, Burges, 1998, Data Mining and Knowledge Discovery, 2:121-167.
In an alternative or additional embodiment of the invention, the SVM is ‘trained’ prior to performing the methods of the invention using biomarker profiles from individuals with known disease status (for example, individuals known to have pancreatic cancer, individuals known to have acute inflammatory pancreatitis, individuals known to have chronic pancreatitis or individuals known to be healthy). By running such training samples, the SVM is able to learn what biomarker profiles are associated with pancreatic cancer. Once the training process is complete, the SVM is then able whether or not the biomarker sample tested is from an individual with pancreatic cancer.
However, this training procedure can be by-passed by pre-programming the SVM with the necessary training parameters. For example, diagnoses can be performed according to the known SVM parameters using the SVM algorithm detailed in Table B, based on the measurement of any or all of the biomarkers listed in Table A.
It will be appreciated by skilled persons that suitable SVM parameters can be determined for any combination of the biomarkers listed in Table A by training an SVM machine with the appropriate selection of data (i.e. biomarker measurements from individuals with known pancreatic cancer status). Alternatively, the Table 2 and 3 data may be used to determine a particular pancreatic cancer-associated disease state according to any other suitable statistical method known in the art.
Preferably, the method of the invention has an accuracy of at least 60%, for example 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% accuracy.
Preferably, the method of the invention has a sensitivity of at least 60%, for example 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sensitivity.
Preferably, the method of the invention has a specificity of at least 60%, for example 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% specificity.
By “accuracy” we mean the proportion of correct outcomes of a method, by “sensitivity” we mean the proportion of all PaC positive sample that are correctly classified as positives, and by “specificity” we mean the proportion of all PaC negative samples that are correctly classified as negatives.
In an alternative or additional embodiment, the individual not afflicted with pancreatic cancer is not afflicted with pancreatic cancer (PaC), chronic pancreatitis (ChP) or acute inflammatory pancreatitis (AIP). More preferably, the healthy individual is not afflicted with any pancreatic disease or condition. Even more preferably, the individual not afflicted with pancreatic cancer is not afflicted with any disease or condition. Most preferably, the individual not afflicted with pancreatic cancer is a healthy individual. By a “healthy individual” we include individuals considered by a skilled person to be physically vigorous and free from physical disease.
However, in another embodiment the individual not afflicted with pancreatic cancer is afflicted with chronic pancreatitis. In still another embodiment, the individual not afflicted with pancreatic cancer is afflicted with acute inflammatory pancreatitis.
As previously mentioned the present method is for determining the presence of pancreatic cancer in an individual. In an alternative or additional embodiment the pancreatic cancer is selected from the group consisting of adenocarcinoma, adenosquamous carcinoma, signet ring cell carcinoma, hepatoid carcinoma, colloid carcinoma, undifferentiated carcinoma, and undifferentiated carcinomas with osteoclast-like giant cells. Preferably, the pancreatic cancer is a pancreatic adenocarcinoma. More preferably, the pancreatic cancer is pancreatic ductal adenocarcinoma, also known as exocrine pancreatic cancer.
In a further embodiment, step (b), (d) and/or step (f) is performed using a first binding agent capable of binding to the one or more biomarkers (i.e., using one or more first binding agent, where in each binding agent is capable of specifically binding to one of the one or more biomarkers). It will be appreciated by persons skilled in the art that the first binding agent may comprise or consist of a single species with specificity for one of the protein biomarkers or a plurality of different species, each with specificity for a different protein biomarker.
Suitable binding agents (also referred to as binding molecules) can be selected from a library, based on their ability to bind a given motif, as discussed below.
At least one type of the binding agents, and more typically all of the types, may comprise or consist of an antibody or antigen-binding fragment of the same, or a variant thereof.
Methods for the production and use of antibodies are well known in the art, for example see Antibodies: A Laboratory Manual, 1988, Harlow & Lane, Cold Spring Harbor Press, ISBN-13: 978-0879693145, Using Antibodies: A Laboratory Manual, 1998, Harlow & Lane, Cold Spring Harbor Press, ISBN-13: 978-0879695446 and Making and Using Antibodies: A Practical Handbook, 2006, Howard & Kaser, CRC Press, ISBN-13: 978-(the disclosures of which are incorporated herein by reference).
Thus, a fragment may contain one or more of the variable heavy (VH) or variable light (VL) domains. For example, the term antibody fragment includes Fab-like molecules (Better et al (1988) Science 240, 1041); Fv molecules (Skerra et al (1988) Science 240, 1038); single-chain Fv (ScFv) molecules where the VH and VL partner domains are linked via a flexible oligopeptide (Bird et al (1988) Science 242, 423; Huston et al (1988) Proc. Natl. Acad. Sci. USA 85, 5879) and single domain antibodies (dAbs) comprising isolated V domains (Ward et al (1989) Nature 341, 544).
The term “antibody variant” includes any synthetic antibodies, recombinant antibodies or antibody hybrids, such as but not limited to, a single-chain antibody molecule produced by phage-display of immunoglobulin light and/or heavy chain variable and/or constant regions, or other immunointeractive molecule capable of binding to an antigen in an immunoassay format that is known to those skilled in the art.
A general review of the techniques involved in the synthesis of antibody fragments which retain their specific binding sites is to be found in Winter & Milstein (1991) Nature 349, 293-299.
Molecular libraries such as antibody libraries (Clackson et al, 1991, Nature 352, 624-628; Marks et al, 1991, J Mol Biol 222(3): 581-97), peptide libraries (Smith, 1985, Science 228(4705): 1315-7), expressed cDNA libraries (Santi et al (2000) J Mol Biol 296(2): 497-508), libraries on other scaffolds than the antibody framework such as affibodies (Gunneriusson et al, 1999, Appl Environ Microbiol 65(9): 4134-40) or libraries based on aptamers (Kenan et al, 1999, Methods Mol Biol 118, 217-31) may be used as a source from which binding molecules that are specific for a given motif are selected for use in the methods of the invention.
The molecular libraries may be expressed in vivo in prokaryotic (Clackson et al, 1991, op. cit.; Marks et al, 1991, op. cit.) or eukaryotic cells (Kieke et al, 1999, Proc Natl Acad Sci USA, 96(10):5651-6) or may be expressed in vitro without involvement of cells (Hanes & Pluckthun, 1997, Proc Natl Acad Sci USA 94(10):4937-42; He & Taussig, 1997, Nucleic Acids Res 25(24):5132-4; Nemoto et al, 1997, FEBS Lett, 414(2):405-8).
In cases when protein based libraries are used often the genes encoding the libraries of potential binding molecules are packaged in viruses and the potential binding molecule is displayed at the surface of the virus (Clackson et al, 1991, op. cit.; Marks et al, 1991, op. cit; Smith, 1985, op. cit.).
The most commonly used such system today is filamentous bacteriophage displaying antibody fragments at their surfaces, the antibody fragments being expressed as a fusion to the minor coat protein of the bacteriophage (Clackson et al, 1991, op. cit.; Marks et al, 1991, op. cit). However, also other systems for display using other viruses (EP 39578), bacteria (Gunneriusson et al, 1999, op. cit.; Daugherty et al, 1998, Protein Eng 11(9):825-32; Daugherty et al, 1999, Protein Eng 12(7):613-21), and yeast (Shusta et al, 1999, J Mol Biol 292(5):949-56) have been used.
In addition, display systems have been developed utilising linkage of the polypeptide product to its encoding mRNA in so called ribosome display systems (Hanes & Pluckthun, 1997, op. cit.; He & Taussig, 1997, op. cit.; Nemoto et al, 1997, op. cit.), or alternatively linkage of the polypeptide product to the encoding DNA (see U.S. Pat. No. 5,856,090 and WO 98/37186).
When potential binding molecules are selected from libraries one or a few selector peptides having defined motifs are usually employed. Amino acid residues that provide structure, decreasing flexibility in the peptide or charged, polar or hydrophobic side chains allowing interaction with the binding molecule may be used in the design of motifs for selector peptides.
For example:
Typically, selection of binding agents may involve the use of array technologies and systems to analyse binding to spots corresponding to types of binding molecules.
In an alternative or additional embodiment, the first binding agent(s) is/are immobilised on a surface (e.g. on a multiwell plate or array).
The variable heavy (VH) and variable light (VL) domains of the antibody are involved in antigen recognition, a fact first recognised by early protease digestion experiments. Further confirmation was found by “humanisation” of rodent antibodies. Variable domains of rodent origin may be fused to constant domains of human origin such that the resultant antibody retains the antigenic specificity of the rodent parented antibody (Morrison et al (1984) Proc. Natl. Acad. Sci. USA 81, 6851-6855).
That antigenic specificity is conferred by variable domains and is independent of the constant domains is known from experiments involving the bacterial expression of antibody fragments, all containing one or more variable domains. These molecules include Fab-like molecules (Better et al (1988) Science 240, 1041); Fv molecules (Skerra et al (1988) Science 240, 1038); single-chain Fv (ScFv) molecules where the VH and VL partner domains are linked via a flexible oligopeptide (Bird et al (1988) Science 242, 423; Huston et al (1988) Proc. Natl. Acad. Sci. USA 85, 5879) and single domain antibodies (dAbs) comprising isolated V domains (Ward et al (1989) Nature 341, 544). A general review of the techniques involved in the synthesis of antibody fragments which retain their specific binding sites is to be found in Winter & Milstein (1991) Nature 349, 293-299.
By “ScFv molecules” we mean molecules wherein the VH and VL partner domains are linked via a flexible oligopeptide.
The advantages of using antibody fragments, rather than whole antibodies, are several-fold. The smaller size of the fragments may lead to improved pharmacological properties, such as better penetration of solid tissue. Effector functions of whole antibodies, such as complement binding, are removed. Fab, Fv, ScFv and dAb antibody fragments can all be expressed in and secreted from E. coli, thus allowing the facile production of large amounts of the said fragments.
Whole antibodies, and F(ab′)2 fragments are “bivalent”. By “bivalent” we mean that the said antibodies and F(ab′)2 fragments have two antigen combining sites. In contrast, Fab, Fv, ScFv and dAb fragments are monovalent, having only one antigen combining sites.
The antibodies may be monoclonal or polyclonal. Suitable monoclonal antibodies may be prepared by known techniques, for example those disclosed in “Monoclonal Antibodies: A manual of techniques”, H Zola (CRC Press, 1988) and in “Monoclonal Hybridoma Antibodies: Techniques and applications”, J G R Hurrell (CRC Press, 1982), both of which are incorporated herein by reference.
In an alternative or additional embodiment, the first binding agent immobilised on a surface (e.g. on a multiwell plate or array).
The advantages of using antibody fragments, rather than whole antibodies, are several-fold. The smaller size of the fragments may lead to improved pharmacological properties, such as better penetration of solid tissue. Effector functions of whole antibodies, such as complement binding, are removed. Fab, Fv, ScFv and dAb antibody fragments can all be expressed in and secreted from E. coli, thus allowing the facile production of large amounts of the said fragments.
Whole antibodies, and F(ab′)2 fragments are “bivalent”. By “bivalent” we mean that the said antibodies and F(ab′)2 fragments have two antigen combining sites. In contrast, Fab, Fv, ScFv and dAb fragments are monovalent, having only one antigen combining sites.
The antibodies may be monoclonal or polyclonal. Suitable monoclonal antibodies may be prepared by known techniques, for example those disclosed in “Monoclonal Antibodies: A manual of techniques”, H Zola (CRC Press, 1988) and in “Monoclonal Hybridoma Antibodies: Techniques and applications”, J G R Hurrell (CRC Press, 1982), both of which are incorporated herein by reference.
Hence, the first binding agent may comprise or consist of an antibody or an antigen-binding fragment thereof. Preferably, the antibody or antigen-binding fragment thereof is a recombinant antibody or antigen-binding fragment thereof. The antibody or antigen-binding fragment thereof may be selected from the group consisting of: scFv, Fab, and a binding domain of an immunoglobulin molecule.
The first binding agent may be immobilised on a surface.
The one or more biomarkers in the test sample may be labelled with a detectable moiety.
By a “detectable moiety” we include the meaning that the moiety is one which may be detected and the relative amount and/or location of the moiety (for example, the location on an array) determined.
Suitable detectable moieties are well known in the art.
Thus, the detectable moiety may be a fluorescent and/or luminescent and/or chemiluminescent moiety which, when exposed to specific conditions, may be detected. For example, a fluorescent moiety may need to be exposed to radiation (i.e. light) at a specific wavelength and intensity to cause excitation of the fluorescent moiety, thereby enabling it to emit detectable fluorescence at a specific wavelength that may be detected.
Alternatively, the detectable moiety may be an enzyme which is capable of converting a (preferably undetectable) substrate into a detectable product that can be visualised and/or detected. Examples of suitable enzymes are discussed in more detail below in relation to, for example, ELISA assays.
Alternatively, the detectable moiety may be a radioactive atom which is useful in imaging. Suitable radioactive atoms include 99mTc and 123I for scintigraphic studies. Other readily detectable moieties include, for example, spin labels for magnetic resonance imaging (MRI) such as 123I again, 131I, 111In, 19F, 13C, 15N, 17O, gadolinium, manganese or iron. Clearly, the agent to be detected (such as, for example, the one or more biomarkers in the test sample and/or control sample described herein and/or an antibody molecule for use in detecting a selected protein) must have sufficient of the appropriate atomic isotopes in order for the detectable moiety to be readily detectable.
The radio- or other labels may be incorporated into the agents of the invention (i.e. the proteins present in the samples of the methods of the invention and/or the binding agents of the invention) in known ways. For example, if the binding moiety is a polypeptide it may be biosynthesised or may be synthesised by chemical amino acid synthesis using suitable amino acid precursors involving, for example, fluorine-19 in place of hydrogen. Labels such as 99mTc, 123I, 186Rh, 188Rh and 111In can, for example, be attached via cysteine residues in the binding moiety. Yttrium-90 can be attached via a lysine residue. The IODOGEN method (Fraker et al (1978) Biochem. Biophys. Res. Comm. 80, 49-57) can be used to incorporate 123I. Reference (“Monoclonal Antibodies in Immunoscintigraphy”, J-F Chatal, CRC Press, 1989) describes other methods in detail. Methods for conjugating other detectable moieties (such as enzymatic, fluorescent, luminescent, chemiluminescent or radioactive moieties) to proteins are well known in the art.
Preferably, the one or more biomarkers in the control sample(s) are labelled with a detectable moiety. The detectable moiety may be selected from the group consisting of: a fluorescent moiety; a luminescent moiety; a chemiluminescent moiety; a radioactive moiety; an enzymatic moiety. However, it is preferred that the detectable moiety is biotin.
In an additional embodiment step (b), (d) and/or step (f) is performed using an assay comprising a second binding agent capable of binding to the one or more biomarkers, the second binding agent comprising a detectable moiety. Preferably, the second binding agent comprises or consists of an antibody or an antigen-binding fragment thereof. Preferably, the antibody or antigen-binding fragment thereof is a recombinant antibody or antigen-binding fragment thereof. Most preferably, the antibody or antigen-binding fragment thereof is selected from the group consisting of: scFv, Fab and a binding domain of an immunoglobulin molecule. In an alternative or additional embodiment the detectable moiety is selected from the group consisting of: a fluorescent moiety; a luminescent moiety; a chemiluminescent moiety; a radioactive moiety and an enzymatic moiety. Preferably, the detectable moiety is fluorescent moiety (for example an Alexa Fluor® dye, e.g. Alexa647).
In an alternative or additional embodiment, the method of the first aspect of the invention comprises or consists of an ELISA (Enzyme Linked Immunosorbent Assay).
Preferred assays for detecting serum or plasma proteins include enzyme linked immunosorbent assays (ELISA), radioimmunoassay (RIA), immunoradiometric assays (IRMA) and immunoenzymatic assays (IEMA), including sandwich assays using monoclonal and/or polyclonal antibodies. Exemplary sandwich assays are described by David et al in U.S. Pat. Nos. 4,376,110 and 4,486,530, hereby incorporated by reference. Antibody staining of cells on slides may be used in methods well known in cytology laboratory diagnostic tests, as well known to those skilled in the art.
Typically, the assay is an ELISA (Enzyme Linked Immunosorbent Assay) which typically involves the use of enzymes giving a coloured reaction product, usually in solid phase assays. Enzymes such as horseradish peroxidase and phosphatase have been widely employed. A way of amplifying the phosphatase reaction is to use NADP as a substrate to generate NAD which now acts as a coenzyme for a second enzyme system. Pyrophosphatase from Escherichia coli provides a good conjugate because the enzyme is not present in tissues, is stable and gives a good reaction colour. Chemi-luminescent systems based on enzymes such as luciferase can also be used.
ELISA methods are well known in the art, for example see The ELISA Guidebook (Methods in Molecular Biology), 2000, Crowther, Humana Press, ISBN-13: 978-0896037281 (the disclosures of which are incorporated by reference).
Conjugation with the vitamin biotin is frequently used since this can readily be detected by its reaction with enzyme-linked avidin or streptavidin to which it binds with great specificity and affinity.
However, step (b), (d) and/or step (f) is alternatively performed using an array. Arrays per se are well known in the art. Typically they are formed of a linear or two-dimensional structure having spaced apart (i.e. discrete) regions (“spots”), each having a finite area, formed on the surface of a solid support. An array can also be a bead structure where each bead can be identified by a molecular code or colour code or identified in a continuous flow. Analysis can also be performed sequentially where the sample is passed over a series of spots each adsorbing the class of molecules from the solution. The solid support is typically glass or a polymer, the most commonly used polymers being cellulose, polyacrylamide, nylon, polystyrene, polyvinyl chloride or polypropylene. The solid supports may be in the form of tubes, beads, discs, silicon chips, microplates, polyvinylidene difluoride (PVDF) membrane, nitrocellulose membrane, nylon membrane, other porous membrane, non-porous membrane (e.g. plastic, polymer, perspex, silicon, amongst others), a plurality of polymeric pins, or a plurality of microtitre wells, or any other surface suitable for immobilising proteins, polynucleotides and other suitable molecules and/or conducting an immunoassay. The binding processes are well known in the art and generally consist of cross-linking covalently binding or physically adsorbing a protein molecule, polynucleotide or the like to the solid support. By using well-known techniques, such as contact or non-contact printing, masking or photolithography, the location of each spot can be defined. For reviews see Jenkins, R. E., Pennington, S. R. (2001, Proteomics, 2, 13-29) and Lal et al (2002, Drug Discov Today 15; 7(18 Suppl):S143-9).
Typically the array is a microarray. By “microarray” we include the meaning of an array of regions having a density of discrete regions of at least about 100/cm2, and preferably at least about 1000/cm2. The regions in a microarray have typical dimensions, e.g., diameters, in the range of between about 10-250 μm, and are separated from other regions in the array by about the same distance. The array may also be a macroarray or a nanoarray.
Once suitable binding molecules (discussed above) have been identified and isolated, the skilled person can manufacture an array using methods well known in the art of molecular biology.
Hence, the array may be the array is a bead-based array or a surface-based array. Preferably, the array is selected from the group consisting of: macroarray, microarray and nanoarray.
In an alternative or additional embodiment, the method according to the first aspect of the invention comprises:
wherein the expression of the dye on the array surface is indicative of the expression of a biomarker from Table A in the sample.
In an alternative embodiment step (b), (d) and/or (f) comprises measuring the expression of a nucleic acid molecule encoding the one or more biomarkers. Preferably the nucleic acid molecule is a cDNA molecule or an mRNA molecule. Most preferably the nucleic acid molecule is an mRNA molecule.
Hence the expression of the one or more biomarker(s) in step (b), (d) and/or (f) may be performed using a method selected from the group consisting of Southern hybridisation, Northern hybridisation, polymerase chain reaction (PCR), reverse transcriptase PCR (RT-PCR), quantitative real-time PCR (qRT-PCR), nanoarray, microarray, macroarray, autoradiography and in situ hybridisation. Preferably, the expression of the one or more biomarker(s) in step (b) is determined using a DNA microarray.
In an alternative or additional embodiment, the measuring of the expression of the one or more biomarker(s) in step (b), (d) and/or (f) is performed using one or more binding moieties, each individually capable of binding selectively to a nucleic acid molecule encoding one of the biomarkers identified in Table A.
In a further embodiment, the one or more binding moieties each comprise or consist of a nucleic acid molecule. Thus, the one or more binding moieties may each comprise or consist of DNA, RNA, PNA, LNA, GNA, TNA or PMO. However, it is preferred that the one or more binding moieties each comprise or consist of DNA.
Preferably, the one or more binding moieties are 5 to 100 nucleotides in length. More preferably, the one or more nucleic acid molecules are 15 to 35 nucleotides in length. More preferably still, the binding moiety comprises a detectable moiety.
In an additional embodiment, the detectable moiety is selected from the group consisting of: a fluorescent moiety; a luminescent moiety; a chemiluminescent moiety; a radioactive moiety (for example, a radioactive atom); and an enzymatic moiety. Preferably, the detectable moiety comprises or consists of a radioactive atom. The radioactive atom may be selected from the group consisting of technetium-99m, iodine-123, iodine-125, iodine-131, indium-111, fluorine-19, carbon-13, nitrogen-15, oxygen-17, phosphorus-32, sulphur-35, deuterium, tritium, rhenium-186, rhenium-188 and yttrium-90.
However, the detectable moiety of the binding moiety may be a fluorescent moiety (for example an Alexa Fluor® dye, e.g. Alexa647).
In an alternative or additional embodiment the sample provided in step (b), (d) and/or (f) is selected from the group consisting of unfractionated blood, plasma, serum, tissue fluid, pancreatic tissue, pancreatic juice, bile and urine. Preferably, the sample provided in step (b), (d) and/or (f) is selected from the group consisting of unfractionated blood, plasma and serum. More preferably, the sample provided in step (b), (d) and/or (f) is plasma. In another preferred embodiment, the sample provided in step (b), (d) and/or (f) is serum.
In an alternative embodiment, the method of the first aspect of the invention is for differentiating body and/or tail pancreatic cancer from head pancreatic cancer comprising or consisting of the steps of:
wherein the expression in the test sample of the at least one biomarker selected from the group defined in Table A (i), (ii) and/or (iii) is indicative of the presence of body and/or tail pancreatic cancer, or head pancreatic cancer. In this embodiment, the test sample may already have been identified as being a pancreatic cancer sample (for example, using the method described above). Alternatively, the test sample may not have been identified as being a pancreatic cancer sample. Positive and negative control samples can be selected appropriately.
In an alternative or additional embodiment, the patient is treated appropriately following identification of a pancreatic cancer. For example, the tumour(s) may be surgically removed (resected), treated with chemotherapy (i.e., anti-neoplastic drugs) and/or treated with radiotherapy. Hence, the present invention includes a method of treating a person having pancreatic cancer, wherein the patient is identified as having pancreatic cancer using the method of the first aspect of the invention.
A second aspect of the present invention provides an array for determining the presence of pancreatic cancer in an individual comprising one or more binding agent as defined in the first aspect of the present invention.
Arrays suitable for use in the methods of the invention are discussed above.
Preferably the one or more binding agents are capable of binding to all of the biomarkers defined in Table A.
A third aspect of the present invention provides the use of one or more biomarkers selected from the group defined in the first aspect of the invention as a diagnostic marker for determining the presence of pancreatic cancer in an individual. Preferably, all of the proteins defined in Table III are used as diagnostic markers for determining the presence of pancreatic cancer in an individual.
A fourth aspect of the present invention provides a kit for determining the presence of pancreatic cancer comprising:
A fifth aspect of the present invention provides the use of one or more binding agents/moieties selected from the group defined in the first aspect of the invention for determining the presence of pancreatic cancer in an individual. Preferably, binding agents/moieties for all of the proteins defined in Table III are used as diagnostic markers for determining the presence of pancreatic cancer in an individual.
Preferred, non-limiting examples which embody certain aspects of the invention will now be described, with reference to the following tables and figures:
Materials and Methods
Samples
After informed consent, 338 serum samples were collected at five different sites in Spain, from patients with pancreatic cancer (PC, n=156), benign controls (BC, n=152), and from normal controls (NC, n=30) (Table 1). The entire set of samples was labeled at a single occasion, using a previously optimized protocol [32, 33]. Briefly, crude samples were diluted 1:45 in PBS, resulting in an approximate protein concentration of 2 mg/mL, and labeled with a 15:1 molar excess of biotin to protein using 0.6 mM EZ-Link Sulfo-NHS-LC-Biotin (Pierce, Rockford, Ill., USA). Unbound biotin was removed by dialysis against PBS for 72 hours. Labeled samples were aliquoted and stored at −20° C.
Antibodies
In total, 293 human recombinant scFv antibodies directed against 98 known serum antigens and 31 4-6 amino acid motifs (here denoted CIMS 1-31) [34], were used as content of the antibody microarrays (See Table 4 for full list of antibodies used). The antibodies were produced in 15 mL E. coli cultures and purified from the periplasm in 300 μL using a MagneHis Protein Purification system (Promega, Madison, Wis., USA) and a KingFisher96 robot (Thermo Fisher Scientific, Waltham, Mass., USA). The elution buffer was exchanged for PBS using Zeba 96-well desalt spin plates (Pierce). The protein yield was measured using NanoDrop (Thermo Scientific, Wilmington, Del., USA) and the purity was checked using 10% SDS-PAGE (Invitrogen, Carlsbad, Calif., USA).
Antibody Microarrays
The antibody microarrays were produced on black MaxiSorp slides (NUNC, Roskilde, Denmark) using a non-contact printer (SciFlexarrayer S11, Scienion, Berlin, Germany). Thirteen identical subarrays were printed on each slide, each array consisting of 31×33 spots, 130 μm in diameter, with 200 μm spot-to-spot center distance. Each subarray consisted of three segments, separated by printed rows of labeled BSA (
Each slide was mounted in a hybridization gasket (Schott, Jena, Germany) and blocked with PBSMT (1% (w/v) milk, 1% (v/v) Tween®-20 in PBS) for one hour. Meantime, aliquots of labeled samples were thawed on ice and diluted 1:10 in PBSMT, in 96-well plates. The slides were washed with PBST (0.05% (v/v) Tween®-20 in PBS) four times before the samples were added from the dilution plates. Samples were incubated for two hours on a rocking table, washed four times with PBST, incubated with 1 μg/mL Streptavidin-Alexa in PBSMT for one hour on a rocking table, and again washed four times with PBST. Finally, the slides were dismounted from the hybridization chambers, quickly immersed in dH2O, and dried under a stream of N2. The slides were immediately scanned in a confocal microarray scanner (PerkinElmer Life and Analytical Sciences, Wellesley, Mass., USA) at 10 μm resolution, using 60% PMT gain and 90% laser power. Signal intensities were quantified using the ScanArray Express software version 4.0 (PerkinElmer Life and Analytical Sciences), using the fixed circle option. Intensities values with local background subtraction were used for data analysis.
Data Pre-Processing
An average value of the three replicate spots was used, unless any replicate CV exceeded 15% from the mean value, in case it was ruled out, and the average value of the two remaining replicates was used instead. The average replicate CV was 8.3% (±5.5%). Applying a cut-off CV of 15%, 70% of data values were calculated from all three replicate spots, and the remaining 30% from two replicates.
For evaluation of normalization strategies and initial analysis of variance, the data was visualized using 3D principal component analysis (QIucore, Lund, Sweden). One (chronic pancreatitis) sample was considered to be an outlier (barely any signals were obtained) and was excluded from the data. Principal component analysis on log 10 raw data showed that no differences between i) sample subarray positioning on slide, ii) patient gender, iii) patient age, and iv) serum sample collection center, could be found. Minor systematic differences could only be observed between days of analysis (rounds 1-5, likely due to small differences in humidity during array printing, in particular for day 1, see
Data Analysis
Analysis was based on two-group comparisons of PC vs. NC and PC vs. BC using PCA, hierarchical clustering, Student's t-test and fold changes, as well as multigroup ANOVA (PC, NC and CP) (Qlucore). Support Vector Machine (SVM) analysis was performed in R (r-project.org) using a linear kernel with the cost of constraints set to one (default value). The data was randomly divided into training and test sets with two thirds of the samples from each group in the training set and the remaining one third of samples in the test set. The backward elimination algorithm was applied using training set data, excluding one antibody at the time and iteratively eliminating the antibody that was removed when the smallest Kullback-Leibler divergence was obtained in the classification analysis, as has been previously described [31]. The last 25 antibodies to be eliminated were used to build a classification model in the training set that was directly applied in the corresponding test set. The area under the ROC-curve (AUC) was used as a measure of the accuracy of the signature in the test set. This procedure was repeated ten times, in ten different, randomly generated pairs of training and test sets. Ultimately, each antibody was given a score based on the order of elimination in the ten training sets. The score was calculated from the average endurance in the elimination process (first antibody to be eliminated=1, last antibody to be eliminated=293). Sensitivities (SN) and specificities (SP) were calculated from the optimal threshold of SVM prediction values, here defined as the highest sum of SN+SP. Finally, pathway analyses were performed using MetaCore (Thomson Reuters, New York, N.Y., USA).
Results
Differential Protein Expression Analysis
Analysis of variance revealed a large number of antibodies with strong differential signaling patterns between cancer and controls in the serum samples. In fact, multigroup ANOVA showed that 75% of the antibodies displayed a significance level of p<0.001 in the serum data. Principal component analysis demonstrated that the cancer samples were clearly more differentiated from normal than from benign controls (
For each subgroup comparison, the 25 antibodies displaying the lowest p-values are shown in Table 2. The PC vs. NC comparison revealed strongly up- and down-regulated analytes, while the PC vs. BC analysis identified analytes with more modest fold changes, and which were almost exclusively upregulated in PC vs. BC (Table 2). The analytes presenting the highest level of differential expression were GAK, IL-6, LDL, and MAPK8 (p≤4·10−20) for PC vs. NC, while a significantly different set of proteins were identified for PC vs. BC, with Cystatin C, IL-13, and IL-la displaying the lowest p-values (p≤3·10−10).
A pathway analysis based on the entire set of antibodies (n=293) with corresponding p-values and fold changes for PC vs. NC, suggested diseases related to insulin production (hyperinsulinism and insulin resistance) as top hits when searching for diseases by biomarkers (
Signatures for Classification
Next, the data was randomly subdivided into training and test sets. The training sets were used to identify the most discriminative combination of antibodies by applying a backward elimination algorithm based on SVM analysis, excluding the antibodies one by one. The classification of PC and NC was highly accurate, as implied by small Kullback-Leibler (K-L) divergences (33.2) throughout the elimination process (
To generate and evaluate signatures of a feasible number of antibodies, we chose the top 25 antibodies from each elimination process and used these to build SVM classification models in the training sets. The AUC values generated by the models in the corresponding test sets were used as a measure of the classification accuracy (
Finally, each antibody was given a score, corresponding to its average endurance in the elimination processes (Table 3). Within the PC vs. NC analysis, the ten signatures were highly similar. For example, the top antibody, targeting IL-11, had an overall score of 291.4 out of 293 eliminations, being the last antibody to be eliminated 4 out of 10 times. In all, the 25 highest scored antibodies for PC vs. NC represented 20 non-redundant analytes, ranging from cytokines and chemokines (IL-11, IL-6, IL-13, IL-8, TNF-α, and Eotaxin), complement components (C1 inhibitor, C1q, C5, and Factor B), enzymes (HADH2, GAK, and ATP-5B) and more. A highly different set of proteins appeared as top markers for PC vs. BC, with MAPK1, TNFRSF3, UCHL5, IL-4, Apo-A1, Apo-A4, CD40 ligand, KSYK and others, among the top scored analytes (Table 3).
Even though the signatures based on antibody score (Table 3) were different from those derived from p-values (Table 2), a significant overlap was observed, particularly for the PC vs. NC signatures, where 8 out of 25 antibodies (IL-11, IL-6, IL-13, HADH2, LDL, GAK, C1q, and TNF-α) appeared in both signatures. All of the top 25 scored antibodies for PC vs. NC were in fact significantly differentially expressed, even if not all being present on the top 25 p-value list.
Tumor Localization
Based on the serum protein profiles, the cancer samples could also be stratified according to tumor origin in the pancreas. Principal component analysis showed that samples from tumors located in the body or the tail of pancreas to some extent clustered closer to the normal controls than what samples from tumors located in the head of pancreas did, and that a separation of the cancer samples based on tumor localization (head vs. body/tail), could be observed (
This study represents one of the largest multicenter analyses of biomarker panels for predicting pancreatic cancer that has been conducted so far. To the best of our knowledge, this is the most multiplexed analysis of serum analytes in such large pancreatic cancer cohort (>300 samples) using affinity proteomics. Analysis was performed using in-house recombinant antibody microarrays, a platform that has advanced over several years [32, 36], and that now include close to 300 antibodies, stringently selected against a range of targets, mainly of the immunoregulatory proteome. Employing novel protocols for high-throughput production and purification, these antibodies are readily generated in less than a week, and rapidly printed in three replicate spots in the picoliter scale onto planar microarrays. In the current set-up, over a hundred samples can be analyzed in parallel per day and workstation, using only minute volumes (<1 μL) of undiluted serum, enabling large sample cohorts to be analyzed in the course of a few days.
In the present study, 338 serum samples were profiled on these arrays, comparing pancreatic cancer to normal and benign controls. Using highly multiplexed assays such as the current one, a certain level of correlation is likely to appear, particularly when highly interconnected proteins such as those of the immune system, are targeted. Even though the discriminative power of individual antibodies, represented by single p-values, might still be of interest, other statistical approaches may be more accurate for identifying the optimal combination of antibodies [37]. Here, a supervised model based on support vector machine analysis was used. The data was divided into training sets from which biomarker signatures were identified by an iterative backward elimination algorithm, and complementary validation sets, in which the classification power of the signatures was tested.
By adopting this approach, lists of proteins of interest were derived both from differential expression patterns, represented by p-values, and from the backward elimination analysis. The latter showed that only 4 to 10 antibodies would be sufficient for close to perfect discrimination of PC vs. NC, results that are highly encouraging and confirm our previous observations that PC can be readily discriminated from healthy controls by assaying the immunoregulatory proteome [23, 24]. However, when PC was compared to BC (mainly chronic pancreatitis), as many as 67 antibodies appeared to be required for optimal classification power. This can partly be explained by the type of proteins measured; the immunoregulatory analytes are not likely to show single-handed disease specificity, as the immune system is highly affected in any condition. Indeed, the pathway analysis conducted in this study, confirmed the highly similar systemic impact of PC and a range of other conditions, such as hyperinsulinism, insulin resistance and metabolic diseases, as well as autoimmunity and infections, again demonstrating the challenge in distinguishing PC from symptomatically related benign conditions. Identifying a relevant immunosignature for PC is thus an act of balance. A small panel is desirable since each binder adds to the cost and complexity of the assay, still the signature needs to be large enough to constitute a sensitive and specific fingerprint of the disease. At this stage of discovery, we reasoned that 25 analytes would be a feasible starting point, and follow-up studies will tell whether these signatures can be condensed to even smaller biomarker panels, while still displaying the sensitivity and specificity required for a diagnostic immunoassay.
Although adopting two highly different strategies for signature identification, there was still a large overlap between the signatures derived from the different analyses, i.e. the markers that obtained the highest overall backward elimination scores were generally also highly differentially expressed. For example, IL-11, IL-6, C1 inhibitor, IL-13, HADH2, LDL, GAK, C1q, and TNF-α appeared in both signatures, and thus demonstrated both low p-values and high backward elimination scores for PC vs. NC. For PC vs. BC the two signatures overlapped by C5, Apo-A4, BTK, TGF-β1, MCP-1, and UPF3B. Of note, a number of markers showed potential for PC both when compared to NC and to BC. Several of these, including C1 inhibitor, C5, Factor B, IL-13, MCP-1, and TNF-α, have been associated with PC in previous studies by us [23, 24] and others [38-40], while HADH2, an acetyl CoA dehydrogenase, has to the best of our knowledge so far not been reported for PC. In addition, other proteins that have not previously been measured by us also showed potential for PC differentiation. For example, GAK, a serine/threonine kinase was heavily down-regulated in PC vs. NC, and also appeared in the backward elimination signatures for PC vs. NC. In addition TNFRSF3 (TNF-β receptor), and UPF3B, an mRNA regulator protein, were included in both the p-value and antibody score signatures for PC vs. BC. Finally, MAPK1 (ERK2), a kinase of the MAPK/ERK signaling pathway which has shown to be deregulated in PC [41], was the highest scored protein in the backward elimination signatures for PC vs. BC.
The serum samples were also stratified on the basis of tumor location in the pancreas, which to the best of our knowledge has not previously been done with proteomics. It was shown that the samples to a certain extent could be separated based on tumor origin, and that the predominant part of samples from patients with tail and body tumors clustered slightly closer to the normal controls than what serum from patients with pancreatic head tumors did. These results thus demonstrated discrepancies in the systemic impact of the cancer based on its origin in the pancreas. The vast number of serum immunoregulatory proteins found to be upregulated in samples from head tumors compared to samples from body/tail tumors, may reflect a more profound systemic impact from tumors located in the pancreatic head, often invading the surrounding mesenteric blood vessels connecting pancreas to the duodenum [3]. These findings thus suggest that serum profiling on antibody microarrays could be applied to distinguish between head and body/tail pancreatic tumors, which potentially could aid in the decision of tumor treatment.
Despite being the 4th most lethal cancer, the incidence of PC is low, ˜11 per 100 000 individuals in the US [42]. From a health-economic perspective, the low incidence makes it difficult to motivate screening for PC in the general population. Based on sensitivities and specificities previously presented by us [24], a recent study however confirms the cost-effectiveness of screening high-risk individuals for PC [43]. Risk factors for PC include not only pancreatitis and benign neoplasms, but also e.g. familial pancreatic cancer, hereditary pancreatitis, BRCA mutations, Peutz-Jeghers syndrome, diabetes mellitus, and Helicobacter pylori infection [44]. The next step will be to explore the signatures identified in the present study, for PC diagnosis among individuals at an increased risk of PC, representing a relevant target population for a diagnostic PC immunoassay.
In conclusion, this extensively multiplexed, multicenter study which revealed immunosignatures associated with pancreatic cancer, displaying sensitivities specificities in the 90-100% range, clearly demonstrated the applicability for PC diagnosis, and also indicated the potential of recombinant antibody microarrays for stratifying serum samples based on tumor location in the pancreas.
2006; 24:87-94.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1319878.3 | Nov 2013 | GB | national |
The present application is a continuation of U.S. patent application Ser. No. 16/161,741, filed Oct. 16, 2018, which is a continuation of U.S. patent application Ser. No. 15/035,953, filed May 11, 2016, which is a § 371 application of PCT/GB2014/053340, filed Nov. 11, 2014, which claims priority to GB Patent Application No. 1319878.3, filed Nov. 11, 2013, the entire disclosure of each of the foregoing being incorporated by reference herein as though set forth in full.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16161741 | Oct 2018 | US |
| Child | 17704057 | US | |
| Parent | 15035953 | May 2016 | US |
| Child | 16161741 | US |
