Abstract:
There is provided a molecular marker CXCR1 for predicting response and survival in subjects afflicted with cancer who would benefit from treatment with and Epidermal Growth Factor Receptor (EGFR) targeted therapeutic.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is concerned with the determination of a molecular marker for use in the prediction of those subjects afflicted by cancer that would benefit from treatment with an Epidermal Growth Factor Receptor (EGFR) targeted therapeutic, specifically but not limited to Cetuximab and Panitumumab. This provides for a method of characterising a tumour to indicate if this tumour will respond to treatment with an EGFR inhibitor and stratifying a subject with a tumour, as a subject who would or would not respond to the treatment with an EGFR inhibitor accordingly. 
       BACKGROUND OF INVENTION 
       [0002]    The Epidermal Growth Factor Receptor (EGFR) and its downstream signaling pathways, primarily the mitogen-activated protein kinase (MAPK) and the phosphatidyl-inositol-3 kinase (PI3K)/Akt pathways, are known to play a significant role in tumour growth and progression. Over-expression of the EGFR has been identified in numerous solid tumours including colon, rectal, lung, ovarian, and head and neck cancers. Many clinical studies have indicated that over-expression of EGFR in these tumours is associated with poor prognosis, and shorter overall survival of subjects afflicted with cancer. 
         [0003]    As EGFR signalling appears to have limited relevant physiological function in an adult, provision of inhibitors of EGFR signalling is believed to allow selective targeting of malignant cells in a subject afflicted by cancer, whilst only causing limited toxicity to normal cells. EGFR has become a widely studied molecular target and major pharmaceutical companies have developed either small molecule inhibitors to EGFR such as Gefitinib (Astrazeneca) and Tarceva (OSI) or antibodies that exhibit high affinity binding and inhibit ligand-induced activation of the EGFR, such as Cetuximab (Eli Lilly/BMS/Merck Serono) and Panitumimab (Amgen). 
         [0004]    Clinical trials of these EGFR targeted therapeutics have indicated that only subsets of patients actually derive clinical benefit from the provision of EGFR-targeted therapeutics. EGFR is expressed in 30-85% of colorectal cancers and its expression level has been linked to reduced survival. Trials conducted in patients with metastatic colorectal cancer have reported favourable response rates in only 23% of patients, even when the EGFR-therapeutic is combined with chemotherapy, and significantly lower response rates of only 11% when the EGFR-therapeutic in used as monotherapy (Saltz et al. J Clin Oncol 2004; 22:1201-1208; Cunningham et al., N Engl J Med 2004; 351:337-345). Identifying which patients respond favourably to the provision of EGFR-therapeutics has thus been a subject of intense research. Importantly, such predictive biomarkers of patient response to EGFR-therapeutics hold the promise to not only improve treatment outcomes for specific patients, but also will enable the full promise of these molecular-targeted therapeutic agents be realized. 
         [0005]    Several early candidates were proposed to serve as predictive biomarkers of response to EGFR-therapeutics, including the expression level of the EGFR itself. Investigations in metastatic colorectal cancer however failed to demonstrate a correlation between EGFR expression as measured by immunohistochemistry and the clinical response to Cetuximab in combination with irinotecan chemotherapy (Chung et al, J Clin Oncol. 2005; 23:1803-1810). Alternatively, while the use of activating mutations in the kinase domain of the EGFR have been successful to predict response to the provision of small molecule agents targeting the kinase domain of the receptor, these mutations are unable to predict response to antibodies such as Cetuximab that bind to the ectodomain of the receptor. Furthermore, mutation rates of the EGFR in certain diseases including colorectal cancer are low, and in diseases where mutations of the EGFR are present, these represent only small populations of the entire patient population (typically &lt;10%) (Janne et al. J Clin Oncol 2005; 23:3227-3234). 
         [0006]    More recent attention has focused on identifying mutations resident within the constituent proteins of the signal transduction pathways that are activated by the EGFR. Following a number of Phase III clinical trials conducted in advanced stage colorectal cancer disease, Cetuximab has been approved for the treatment of subjects with epidermal growth factor receptor (EGFR)-expressing, KRAS wild-type metastatic, colorectal cancer (mCRC), in combination with chemotherapy, on the basis that tumours that do not harbour mutations are more likely to respond to EGFR-targeted treatment strategies. However, larger trials that have enrolled significantly larger numbers of patients have subsequently reported that use of KRAS status does not clearly predict response to EGFR therapeutics. For example, the randomized phase III COIN study, in which greater than 2500 patients took part, failed to observe any benefit from the addition of Cetuximab to oxaliplatin-based chemotherapy in first-line treatment of patients with advanced colorectal cancer. While the study showed that Cetuximab increased the response rate measured at 12 weeks after therapy, there was no evidence of benefit in terms of progression-free survival or overall survival in KRAS wild-type patients or even in patients selected by additional mutational analysis of their tumours (Maughan et al., Lancet Oncol 2011; 377:2103-2114). Therefore additional biomarkers are required to accurately select patients and differentiate responsive from non-responsive subjects. 
         [0007]    Given the intention in the provision of therapy or use of a therapeutic agent to improve clinical outcome through a beneficial response, it would be advantageous to provide a diagnostic test that identifies responsive subjects to the therapy/therapeutic agent being considered. This is particularly advantageous to identify those subjects who are unlikely to benefit and are therefore unnecessarily exposed to toxic side effects of therapeutic agents. Further, it is advantageous to minimise the likelihood of unnecessary expense being incurred through treatment of subjects with therapy/therapeutic agents that are unlikely to provide benefit, and/or minimise the delay in a subject being treated with an alternative drug(s) which might prove more beneficial. 
       SUMMARY OF INVENTION 
       [0008]    The inventors have determined that the expression level of CXCR1 in a tumour of a cancer subject can be indicative of beneficial drug response and survival of a cancer subject treated with an EGFR inhibitor. In particular, the inventors have identified CXCR1 as a predictive biomarker to identify or predict those subjects who will benefit from treatment with the EGFR-targeted therapeutic Cetuximab (or other agents including Panitumumab) and in particular those colorectal cancer subjects who will benefit from the addition of EGFR-targeted therapeutics to cytotoxic (e.g. oxaliplatin-based) chemotherapy. 
         [0009]    Accordingly a first aspect of the invention provides the use of CXCR1 as a biomarker in a method of predicting response in a subject to treatment with an Epidermal Growth Factor Receptor therapeutic, in particular an EGFR inhibitor, wherein an expression level of CXCR1 in a tumour sample of a cancer subject increased from that of the expression level of CXCR1 in a Control is indicative the subject will respond to treatment with the EGFR therapeutic. 
         [0010]    Although prior studies in the literature suggest that ligand-induced activation of G-protein coupled receptors can induce an intracellular transactivation of growth factor receptors, including the EGFR receptor, ((Venkatakrishnan et al, J Biol Chem 2000; 275:6868-6875) and (Kyriakis et al. J Leukocye Biol 2011; 90:929-939)) and transactivation of the EGFR has been indicated to constitute an important aspect of interleukin-8 signaling underpining many cellular responses including proliferation and survival (Waugh and Wilson, Clin Cancer Res 2008; 14; 6735-6741) and (Itoh et al, Cytokine 2005; 29:275-282), to date biomarkers for EGFR targeted therapeutics have been largely determined by considering the levels of response indicator genes following treatment with an EGFR targeted therapeutic in responding and non-responding subjects. 
         [0011]    In contrast, whilst not wishing to be bound by theory, the present inventors have determined tumour sensitivity to EGFR-therapeutics can be predicted based on the tumour having robust EGFR signaling, wherein such a tumour becomes “addicted” to the EGFR signaling pathway, and is hyper-sensitive to the loss of EGFR signalling, wherein dependence of the tumour on the EGFR signaling pathway for proliferation and survival can be detected by considering whether a tumour is CXCR1 enriched relative to tumors from non-responding subjects. 
         [0012]    In embodiments, it is considered the IL8 receptor CXCR1 is as an independent predictor of therapeutic response to EGFR-targeted therapeutics in metastatic colorectal cancer subjects. 
         [0013]    In embodiments the method can comprise the steps: determining in a tumour sample from a cancer subject the expression level of CXCR1; comparing the determined expression level of CXCR1 against the expression level of CXCR1 in a Control, for example from tumours of a control population, where the tumours of the Control population may be tumours of the same tissue as the tumour of the subject, and may be of equivalent stage and grade as the tumour of the subject, wherein when the expression level of CXCR1 determined in the subject is determined to be increased above the expression level of the Control, for example the median expression level within a control population, it is indicative that the cancer subject would benefit from treatment with an EGFR modulator/Epidermal Growth Factor Receptor therapeutic. In embodiments the method can comprise the steps of: determining the expression level of CXCR1 in a tumour sample of a tumor from a subject, comparing the determined level with the expression level of CXCR1 in a control sample wherein when the expression level of CXCR1 in the tumour from the subject is greater than the expression level of CXCR1, suitably the median expression level of CXCR1 characterised in a control sample of the respective cancer or tumour tissue, the tumour is determined as EGFR inhibitor sensitive and the subject will likely respond to treatment with an EGFR inhibitor. In embodiments, the control sample can be generated determined on the expression level determined in a control population. In embodiments, a control sample can be from a tumour representative of a median expression level of CXCR1 in tumours of the same tissue type, more suitably of the same stage and grade, as that of the subject. Suitably the control sample may be synthetically or artificially provided based on results from tumour representative of a median expression level of CXCR1 in tumours of the same tissue type as that of the subject. 
         [0014]    Suitably when the expression level of CXCR1 of a tumour of the subject is increased with respect to a Control CXCR1 expression level of a sample tumour, preferably the median expression level of CXCR1 of the Control, the tumour may be characterised as EGFR inhibitor sensitive and the subject will likely beneficially respond therapeutically to treatment with an EGFR inhibitor and thus be classified as a responder. 
         [0015]    In embodiments the method is an in vitro method wherein the step of determining the expression level of CXCR1 can comprise taking a biological sample from the subject and then measuring the expression level of CXCR1 in the sample. In embodiments a tumour sample can be a tissue sample comprising cancer cells from the cancer subject. For example, a tumour sample can be obtained from a subject prior to and after exposure of the cancer cells to an EGFR targeted therapeutic or other chemotherapeutic agent. In embodiments the tumour sample can be an ex vivo tumour cell. The tumour sample can be, for example, a tissue sample comprising cancer cells wherein the tissue sample is frozen, fixed, paraffin embedded, or fresh. The tissue may be from a biopsy. The term also encompasses cells that are the progeny of a subject&#39;s tumour, e.g. cell culture samples derived from a primary tumour or samples comprising cells, protein or nucleic acid shed from a tumour. 
         [0016]    In embodiments of the invention, the method can include the step of analysing a circulating tumour cell or tissue sample from a subject&#39;s tumour, including, but not limited to, the use of a diagnostic tissue sample obtained from the subject at the time of presentation for expression of the biomarker. The step of analysing may include traditional immunohistochemistry-based analysis to determine the expression of the defined predictive biomarker CXCR1 as discussed herein. In embodiments, determining an expression level of a CXCR1 above or increased with respect to the expression level of a Control, indicative that a cancer subject would benefit from treatment with an EGFR targeted therapeutic, can comprise the steps of;
       analysing a tissue sample from a cancer subject&#39;s tumour, or cells from a subject&#39;s tumour including the analysis of circulating tumour cells from the blood or other bodily sample taken from the subject,   determining the expression level of the biomarker CXCR1,   determining whether the level of the biomarker is greater than that of a Control,   wherein an expression level of the biomarker above the Control is indicative the subject will gain clinical benefit (beneficially respond) from the provision of an EGFR therapeutic. In embodiments a Control can be a median expression level of CXCR1 of a cancer population with tumours of the same tissue type, preferably the same stage and/or grade as the tumour from the subject.       
 
       Subject 
       [0021]    As will be appreciated, the method provides for the identification of a subgroup of cancer subjects (responders) who will benefit from treatment with an EGFR targeted therapeutic, in particular an EGFR inhibitor. Accordingly, an EGFR inhibitor, in particular cetuximab or panitumumab, may be provided to a subject for use in the treatment of a tumour in the subject wherein a tumour sample from said tumour has been identified to have an expression level of the CXCR1 biomarker that is above or increased with respect to a level in a Control tumour sample. Also provided is the use of an EGFR inhibitor, in particular cetuximab or panitumumab, in the manufacture of a medicament for the treatment of a subject with cancer, wherein a tumour from said cancer has been identified to have an expression level of CXCR1 above the expression level of a control tumour sample. Further provided is a method of treating a subject with a tumour wherein the expression level of CXCR1 in the tumour is greater than the expression level of CXCR1 in a Control, wherein the method comprises administering an EGFR inhibitor to the subject. In embodiments a subject may have been previously treated with or will be receiving chemotherapy or radiotherapy including standard conformal radiotherapy, intensity-modulated radiotherapy or cyber-knife radiotherapy. In embodiments the cells from a cancer subject&#39;s tumour can have been subjected to chemotherapy prior to the assay method. In embodiments, patients with colorectal cancer may have previously been subjected to treatment with oxaliplatin, irinotecan or fluoropyrimidine therapy prior to the assay method. 
         [0022]    In embodiments the cancer subject can be a candidate for treatment with Gefitinib (Astrazeneca), Tarceva (OSI), Cetuximab (Merck Serono), Panitumimab (Amgen) or any other anti EGFR drugs or for the screening of drugs for anti EGFR activity. In embodiments the cancer subject can be a candidate for treatment with Cetuximab (Merck Serono) or Panitumimab (Amgen). In an embodiment the cancer subject can be a candidate for treatment with Cetuximab (Merck Serono). 
         [0023]    The EGFR therapeutic agent may exhibit differential degrees of selectivity or specificity to members of the extended EGFR-family of receptors including ErbB2, ErbB3 and ErbB4. In particular embodiments, treatment with an EGFR inhibitor is by treatment with Cetuximab or panitumumab, more particularly treatment with Cetuximab. 
       Tumour 
       [0024]    The tumour or cancer may be selected from colorectal cancer, preferably metastatic colorectal cancer, colorectal tumours, NSCLC tumours, head and neck tumours and ovarian tumours. In embodiments the cancer subject can have a solid tumour, for example, within the colon, lungs, ovaries, colon or gastro-intestinal tract, or head and neck. In embodiments the cancer subject can have colon cancer, rectal cancer, lung cancer, ovarian cancer, gastro-oesophageal cancer and head and neck cancer. In embodiments the cancer subject can have a primary tumour within the colon, rectum, gastro-oesphoageal tract, ovaries or head and neck, with secondary metastatic lesions disseminated to other tissues within the body. In embodiments, where the cancer is pathologically confirmed as colorectal cancer, the use of CXCR1 as a predictive biomarker may be used in relation to any subject being considered for treatment with an EGFR inhibitor in the adjuvant or metastatic disease setting, as would be the case for performing a Ras-mutation analysis currently. Alternatively, the use of CXCR1 as a biomarker to indicate those subjects that will respond to treatment with an EGFR therapeutic may also be used to guide the provision of an EGFR inhibitor in patients with solid tumours classified as non-small cell lung cancer (NSCLC), head and neck cancer, and ovarian cancer etc. 
         [0025]    Representative nucleic acid sequences and amino acid sequences for CXCR1 are provided in the sequence listing at the end of the specification. As will be appreciated, nucleic acid or amino acid variants of these sequences exist and are encompassed by the present application. 
         [0026]    The expression level of the CXCR1 biomarker in a Control may be set at the mean, mode or preferably the median level of expression (median expression level) or further defined value as observed across a spectrum of respective cancer tissue, for example colorectal cancer tissue. In embodiments the expression level of the CXCR1 biomarker in a Control can be the expression level, suitably the mean, mode or preferably median expression level, as determined in tumours of the same tissue type as that of the tumour of the subject being tested. In embodiments the expression level of the of the CXCR1 biomarker in a Control can be the expression level, suitably the mean, mode or prefereably median expression level as determined in tumours of the same tissue type and equivalent stage and grade as that of the tumour of the subject being tested. This provides a normalised expression level and the normalised expression level can be used to determine an increased expression level which is indicative that beneficial response will be observed when an EGFR inhibitor is administered to the subject. Additionally, reference expression levels to define the normal range of expression of the biomarker in a tumour(s) may be provided by considering a sub population of cancer subjects, for example subjects suffering from invasive tumours, an age range of subjects, the gender of subjects, or a selection of subjects based on expression of another biomarker. As will be appreciated, the determination of the subjects from which samples may be provided can typically be made in view of the subjects to be studied, or tumours to be assessed/classified as responder/non-responder. In embodiments, the expression level of CXCR1 in a tumour can be considered relative to the cellular location of the expression and corresponding expression at that cellular location in the control, for example the expression level of CXCR1 may be localized to the cell-membrane, the cytoplasmic compartment of the cell, the nuclear and peri-nuclear zones of the cell or be resident within exosomal bodies within or out-with the tumour mass. 
         [0027]    By “above, increased or greater than” is meant expression levels of the biomarker determined in the sample above the normalised expression level of the biomarker in a Control or a level of biomarker that has been correlated with an increased likelihood the subject will exhibit a beneficial response to an EGFR inhibitor cancer therapy. A likelihood score which is indicative of the likelihood of beneficial response to EGFR inhibitor treatment may be determined using weighted values based on an expression level of CXCR1 and the contribution to response to EGFR inhibitor cancer therapy based on the level of CXCR1. It is contemplated that an incremental increase in the level of, for example CXCR1 above a Control, may provide for an incremental increase in clinical outcome to provision of an EGFR-targeting therapeutic. By “beneficial response” is meant a favourable subject response to a drug as opposed to an unfavourable response. Favourable subject response may be assessed by determining one or more of the loss of detectable tumour, decrease in tumour size, decrease in tumour number, tumour growth arrest, enhancement of anti-tumour immune response, regression or rejection of the tumour, relief to some extent of one or more symptoms associated with the tumour, and/or an increase in the length of survival following treatment. 
         [0028]    As will be appreciated, the methods of the invention may further comprise the step of designing a treatment regimen for a subject. For example, an anti-EGFR antibody may be administered to those subjects including a tumour which has increased (or above-median) expression of CXCR1. In contrast to this, other drug regimens, for example chemotherapeutic therapies, could be administered to a subject with a tumour which has a decreased expression level of CXCR1. 
         [0029]    In embodiments, the Control expression level can be as provided in the examples discussed herein. As will be understood, the Control expression level can be generated for specific cancer types, or specific subtypes of subjects based on age or the like to allow for the comparison of the expression level detected or measured from the subject&#39;s tumour. 
       Determining the Expression Level 
       [0030]    In embodiments, determining the expression level can comprise as least one of 
         [0000]    determining the expression of CXCR1 protein in a tumour or tumour-derived sample taken from the subject
 
determining the amount of mRNA encoding CXCR1 in a tumour or tumour-derived sample taken from the subject,
 
determining the copy number of CXCR1 in a tumour or tumour-derived sample taken from the subject,
 
determining and characterizing the expression of any non-coding or coding polymorphism within the nucleotide sequences encoding CXCR1 in a tumour, tumour-derived or non-tumour tissue sample taken from the subject.
 
         [0031]    Suitably an increased copy number is indicative that administration of an EGFR inhibitor will provide a beneficial response to a subject. By copy number is meant the number of discrete instances of a gene encoding for a biomarker as indicated as present in a tumour sample when compared to a reference sample. Normal copy number would be defined as the normal copy of the gene determined in healthy subjects and healthy tissue specimens. The reference sample may be provided from a sub-population of cancer subjects or an appropriately matched cohort of normal patients. Copy number may be determined by methods as will be known in the art. Exemplary methods include, but are not limited to, hybridisation-based assays, amplification-based assays and gene transcription or protein expression assays. 
         [0032]    Suitably, any one of the determinations of expression level of the biomarker, CXCR1, may be used in combination in the methods of the invention. 
         [0033]    Methods for determining the amount of biomarker polypeptide CXCR1 or the amount of mRNA encoding biomarker CXCR1 in a sample are disclosed herein and would generally be known to those of skill in the art. In embodiments, determining the level of expression of biomarker polypeptide, CXCR1, may comprise determining the level of activity of the receptor, and/or determining the level of interaction between the biomarker (CXCR1) and a binding partner (e.g, IL-8 or GCP-2). 
         [0034]    In embodiments of the methods of the invention the expression level can be measured by determining the mRNA level of the CXCR1 biomarker (measured, for example using reverse-transcriptase polymerase chain reaction (RT-PCR), quantitative RT-PCR methodology or other PCR methodologies, Northern blot, in-situ hybridisation, dot-blot, Taqman, RNAse protection assay or using array hybridisation, for example microarray). In such embodiments, probes of nucleic acid molecules that can hybridise to mRNA of the biomarker CXCR1, under stringent conditions can be used to identify the expression level of the biomarker CXCR1. PCR methods to allow for amplification of nucleic acid to allow determination of the level of expression are well known. Rules for designing PCR primers are now established in the art. 
         [0035]    These methods can include chip based technologies for the detection and/or quantification of nucleic acid. In such methods, microarrays may be used wherein polynucleotide sequences of interest are arrayed on a substrate. These can include oligonucleotide microarrays or cDNA microarrays comprising one or more of the biomarkers that correlate with sensitivity to an EGFR inhibitor. The arrayed sequences are then contacted under conditions suitable for specific hybridization with detectably labelled cDNA generated from mRNA of a test sample. The mRNA is typically total RNA isolated from a tumour sample. Based on the gene expression profile of a tumour sample from a cancer subject, for example from a tumour biopsy, it can be determined if the cells differ from control cells and if so whether they show a resistant or sensitive profile to the cancer treatment with an EGFR inhibitor. 
         [0036]    Quantification of hybridization of each arrayed element allows for assessment of corresponding mRNA abundance. Microarray analysis may, for example, be performed using commercially available equipment, for example using Affymetrix GenChip® technology. 
         [0037]    In another embodiment the expression level can be measured by determining the protein level of the CXCR1 biomarker (measured, for example, by immunohistochemistry proteomics techniques, for example using a commercially available CXCR1 monoclonal antibody, Enzyme Linked Immunosorbent assay (ELISA), 2-dimensional SDS PAGE, Western blot, Immunoprecipitation, fluorescence activated cell sorting (FACS) or flow cytometry). These methods can include membrane, solution or chip based technologies for the detection and/or quantification of CXCR1 protein. 
         [0038]    Expression of the CXCR1 biomarker may be detected and measured using antibody-based approaches, wherein either polyclonal or monoclonal antibodies specific for the biomarker, CXCR1, can be used to detect tumour epithelial expression. Typically, an antibody which specifically binds to the biomarker as disclosed herein, for example CXCR1 provides a detection signal that results from specific binding to its target protein and that it does not detect other proteins in immunochemical assays and can immunoprecipitate CXCR1 from solution. Immunohistochemical determination of the level of a biomarker referenced herein, for example CXCR1, will be essentially qualitative. However, this can still allow prognostic grouping of a subject being tested as an EGFR modulator, for example inhibitor, responder or non responder. 
         [0039]    Determination of the level of expression of at least one of CXCR1 may be qualitative (for example higher or lower than Control from considering for example immunohistochemical stained sample) or quantitative. In embodiments, optionally, the expression level of a biomarker can be at least two-fold, at least three-fold, at least four-fold or higher than that of a Control. In other embodiments, optionally, the expression level of a biomarker can be determined to be p-value &lt;0.05 in Anova (t test) or other relevant statistical analysis. 
         [0040]    In embodiments, the methods of the invention can be carried out in vitro, for example on samples obtained from a subject. In alternative embodiments, some methods of the invention may be practiced on data previously generated from a subject (for example from data generated from microarray data of a tumour sample) and thus do not require the direct use of a physical patient sample. For each aspect of the invention, the methods may include the further step of creating a report for a subject containing a summary of the expression levels of the biomarker CXCR1, in a tumour sample. In one aspect this report is an electronic form. 
         [0041]    In embodiments the use of the biomarker described in the invention CXCR1 may be used in tandem with other defined biomarkers. In embodiments at least one biomarker used in these protocols includes CXCR1 or fragments thereof which provide for determination of CXCR1 expression or activity in a cell. In embodiments at least one biomarker is selected from CXCR1. 
         [0042]    In embodiments, the use of CXCR1 as a biomarker, can be used alone or in combination with other biomarkers as a predictive test or means to select subjects that will likely respond beneficially to 
         [0000]    administration of an EGFR targeted therapeutic, for example an EGFR inhibitor, in combination with oxaliplatin-based chemotherapy as a treatment for stage 1V or metastatic colorectal cancer,
 
administration of an EGFR targeted therapeutic, for example an EGFR inhibitor, in combination with irinotecan based chemotherapy as treatment for stage 1V or metastatic colorectal cancer,
 
administration of an EGFR targeted therapeutic, for example an EGFR inhibitor, in combination with fluoropyrimidine based chemotherapy as a treatment for stage 1V or metastatic colorectal cancer, or
 
administration of an EGFR targeted therapeutic, for example an EGFR inhibitor, in combination with another approved cancer chemotherapeutic agent as an adjuvant based post surgical treatment for subjects diagnosed with early stage (stage II/III) colorectal cancer including but not limited to a combination of oxaliplatinum, irinotecan and/or fluoropyrimidine-based chemotherapy.
 
         [0043]    In embodiments, the results of the methods of the invention can be communicated to parties including a physician, a researcher or a subject for use in determining further treatment options. In embodiments the results can be provided in a form which are transmittable to such parties. The results may be provided in a tangible form such as paper, computer readable media or the like or on an intangible medium, for example an electronic signal, email, or via a website. Alternatively, the results may be recorded in a sound and transmitted through a suitable medium such as digital cable lines, fiber optic cables, wireless or the like. Accordingly, the methods can encompass a method of producing a transmittable form of a result of the expression level of a biomarker, preferably CXCR1 in a tumour sample. 
         [0044]    In a further aspect there is provided a method to determine the likelihood that a cancer subject will respond therapeutically to a cancer treatment wherein the method comprises a) measuring the expression level of the CXCR1 biomarker in a biological sample from the cancer subject, b) exposing the biological sample to a cancer treatment that includes an EGFR targeted therapeutic, c) following the step b) of exposing the biological sample to the cancer treatment, measuring the expression level of CXCR1 as an indicator of the response of the tumour or tumour-derived sample and comparing the expression level of CXCR1 as an indicator of the response of the tumour or tumour-derived sample to that of the expression level of the CXCR1 biomarker in a biological sample from the cancer subject at step a). 
         [0045]    In embodiments, measuring the expression level of CXCR1 may include the assessment of a cellular or molecular readout, so that the analysis predicts an increased likelihood that the cancer subject will respond beneficially to an EGFR modulator. 
         [0046]    In embodiments the method enables the identification and/or selection of patients to receive an EGEF targeted therapeutic, for example Cetuximab, for the treatment of cancer, in particular any-stage of colorectal cancer. In embodiments the method can enable the selection of cancer subjects to receive an EGFR targeted therapeutic, for example Cetuximab, for stage II colorectal cancer following surgical resection. In embodiments, the patients may receive Cetuximab as a monotherapy or as a component of adjuvant-treatment. 
         [0047]    The methods of the invention may be used to provide screening assays to determine whether a subject is susceptible or resistant to treatment with one or more EGFR modulators/EGFR targeted therapeutics. The methods of the invention may be used to monitor the treatment of a subject having cancer, wherein the cancer is treated by administering one or more EGFR modulators/EGFR targeted therapeutics. The CXCR1 biomarker can be used to monitor the progress of disease treatment in those subjects undergoing treatment to determine if there is a change in the sensitivity of the tumour to treatment with and EFGR modulator/EGFR targeted therapeutic. The methods of the invention may be used to provide genetic profiles of cancer subjects which can enable treatment strategies to be provided to a specific subject. 
       Kits 
       [0048]    The invention also provides kits for determining or predicting whether a subject is susceptible to a cancer treatment. 
         [0049]    In one aspect there is provided a kit for use in a method of the invention comprising a container comprising one or more reagents for monitoring the expression level of CXCR1, and one or more EGFR modulators for use in testing cells from a cancer subject. In an embodiment, a reagent of the kit can be an antibody with binding specificity to the CXCR1 biomarker. In another embodiment the reagent of the kit can be a microarray to enable the level of mRNA of the biomarker CXCR1 to be determined. In another embodiment, the reagent of the kit can comprise a PCR probe with binding specificity to a mRNA of a biomarker CXCR1 to be determined. In embodiments, the kit can further comprise instructions for determining whether or not a cancer subject will respond therapeutically to a method of treating cancer, specifically a method of treating cancer comprising an EGFR inhibitor. In particular embodiments of the kit, the kit may further comprise antibodies with binding specificity to at least one additional biomarker, and/or PCR probes with binding specificity to at least one additional biomarker. 
         [0050]    In embodiments, CXCR1 includes active forms of CXCR1 and active fragments thereof. In embodiments at least one biomarker can be selected from CXCR1 as indicated by SEQ ID NO:1 or SEQ ID NO:2. Other additional biomarkers may include CXCR2, CXCR4, CXCR7, CXCL12, CXCL1, CXCL5 or CXCL6. 
         [0051]    In an embodiment, the kit can determine or predict whether a patient would be susceptible to respond to a cancer treatment comprising an EGFR inhibitor. 
         [0052]    In all aspects of the present disclosure, there may be provided the further step of determining the expression level of at least one further biomarker. In embodiments, the methods may include determination of at least three biomarkers, at least four biomarkers, at least five biomarkers or more. In embodiments a further biomarker can be selected from other previously reported biomarkers including mutant EGFR, gain-of-function mutations in K-Ras, loss of PTEN and/or p53 functionality through mutation or diminished expression. The detection of mutated K-Ras is typically considered to be indicative that there will be a decreased likelihood of the cancer subject responding therapeutically to a method of treating cancer comprising administering an EGFR inhibitor. A biomarker may be used in an in vitro assay to predict in vivo outcome. In a further embodiment of the invention, the additional biomarkers may be novel/newly-described biomarkers identified from genome-wide screens (e.g. microarray) or through hypothesis-driven research. 
         [0053]    Preferred features and embodiments of each aspect of the invention are as for each of the other aspects mutatis mutandis unless context demands otherwise. 
       DEFINITION OF TERMS 
       [0054]    “Probes” may be derived from naturally occurring or recombinant single- or double stranded nucleic acids or may be chemically synthesised. Such probes may be labelled with reporter molecules. Nucleic acid probes may be used in Southern, Northern or in situ hybridizations to determine whether DNA or RNA encoding a biomarker is present within a cell type, tissue or organ. Probes can also be antibodies which have binding specificity to a biomarker. 
         [0055]    “Reporter molecules” can be fluorescent, chemiluminescent, or chromogenic agents, radionuclides, and enzymes which are associated to a probe and allow the detection of the probe. 
         [0056]    “Stringent conditions” refers to conditions that allow for hybridization of substantially related nucleic acid sequences. Stringent conditions, within the meaning of the invention are 65° C. in a buffer containing 1 mM EDTA, 0.5M NaHPO4 (pH7.2), 7% (w/v) SDS. For instance, such conditions will generally allow hybridization of sequence with at least 85% identity, preferably at least about 90% sequence identity, more preferably with at least 95% sequence identity. Hybridization conditions and probes can be adjusted in well characterised ways to achieve selective hybridization. 
         [0057]    “Active”, with respect to a CXCR1 polypeptide or other CXCR or CXCL polypeptides refers to those forms, fragments or domains of CXCR1 polypeptide which retain biological and/or antigenic activity of a CXCR or CXCL polypeptide. 
         [0058]    “EGFR modulators or EGFR targeted therapeutics” as used herein is intended to mean a compound or drug, for example a biological molecule or small molecule that directly or indirectly modulates the EFGR signal transduction pathway. EGFR modulators or EGFR targeted therapeutics can include EGFR specific ligands, small molecule EGFR inhibitors, EGFR monoclonal antibodies and chimeric versions of such antibodies. EGFR modulators or EGFR targeted therapeutics may include biological molecules or small molecules. Biological molecules may include all lipids and polymers of monosaccharides, amino acids and nucleotides having a molecular weight greater than 450 kDa. Thus biological molecules include, for example, oligosaccharides and polysaccharides; oligopeptides, polypeptides, peptides and proteins, and oligonucleotides and polynucleotides. Oligonucleotides and polynucleotides include for example DNA and RNA. Biological molecules further include derivatives of any of the molecules described above. For example, derivatives of biological molecules including lipid and glycosylation derivatives of oligopeptides, poplypeptides, peptides, and proteins. Derivatives of biological molecules further include lipid derivatives of oligosaccharides and polysaccharides e.g. lipopolysaccharides. Most typically, biological molecules are antibodies or functional equivalents of antibodies wherein the functional equivalents have binding characteristics comparable to those of antibodies and inhibit the growth of cells that express EGFR. Such functional equivalents can include chimeric, humanised, and single chain antibodies as well as fragments thereof. Functional equivalents of antibodies also include polypeptides with amino acid sequences substantially the same as the amino acid sequence of the variable or hypervariable regions of the antibodies, for example wherein the amino acid sequence differs from the other sequence by means of one or more substitions, deletions and/or additions. Preferably less than 50%, more preferably less than 25%, more still more preferably less than 10% of the number of amino acids in a sequence are substituted, added and/or deleted from the protein. 
         [0059]    In embodiments an EGFR antibody can be selected from the antibodies described in U.S. Pat. No. 6,235,883, U.S. Pat. No. 5,558,864, and U.S. Pat. No. 5,891,996. The EGFR antibody can be, for example, AGX-EGF (Amgen Inc.) (also known as panitumumab) which is a fully human IgG2 monoclonal antibody. The sequence and characterization of ABX-EGF, which was formerly known as clone E7.6.3, is disclosed in U.S. Pat. No. 6,235,883 at column 28, line 62 through column 29, line 36 and  FIGS. 29-34 , which is incorporated by reference herein. The EGFR antibody can also be, for example, EMD72000 (Merck KGaA), which is a humanized version of the murine EGFR antibody EMD 55900. The EGFR antibody can also be, for example: h-R3 (TheraCIM), which is a humanized EGFR monoclonal antibody; Y10 which is a murine monoclonal antibody raised against a murine homologue of the human EGFRvIII mutation; or MDX-447 (Medarex Inc.). 
         [0060]    EGFR modulators or EGFR targeted therapeutics useful in the invention may also be small molecules. These can include a molecule that is not a biological molecule. Some examples of small molecules include organic compounds, organometallic compounds, salts of organic and organometallic compounds, saccharides, amino acids, and nucleotides. Small molecules further include molecules that would otherwise be considered biological molecules, except their molecular weight is not greater than 450 kDa. Thus, small molecules may be lipids, oligosaccharides, oligopeptides, and oligonucleotides and their derivatives, having a molecular weight of 450 kDa or less. 
         [0061]    Small molecules include compounds that are found in nature as well as synthetic compounds. In one embodiment, the EGFR modulator is a small molecule that inhibits the growth of tumor cells that express EGFR. In another embodiment, the EGFR modulator is a small molecule that inhibits the growth of refractory tumor cells that express EGFR. ERESSA (ZD1939), which is a quinozaline derivative that functions as an ATP-mimetic to inhibit EGFR. See, U.S. Pat. No. 5,616,582; WO 96/33980 at page 4 is an example of a small molecule EGFR antagonist. Another example of a small molecule EGFR antagonist is TARCEVA (OSI-774), which is a 4-(substitutedphenylamino)quinozaline derivative [6,7-Bis(2-methoxy-ethoxy)-quinazolin-4-yl]-(3-ethynyl-1-phenyl)amine hydrochloride] EGFR inhibitor See WO 96/30347 (Pfizer Inc.) at, for example, page 2, line 12 through page 4, line 34 and page 19, lines 14-17. TARCEVA may function by inhibiting phosphorylation of EGFR and its downstream PI3/Akt and MAP (mitogen activated protein) kinase signal transduction pathways resulting in p27-mediated cell-cycle arrest. See Hidalgo et al., Abstract 281 presented at the 37th Annual Meeting of ASCO, San Francisco, Calif., 12-15 May 2001. 
         [0062]    Other small molecules are also reported to inhibit EGFR, many of which are thought to be specific to the tyrosine kinase domain of an EGFR. Some examples of such small molecule EGFR antagonists are described in WO 91/116051, WO96/30347, WO96/33980, WO97/27199. WO97/30034, WO97/42187, WO97/49688, WO98/33798, WO00/18761, and WO00/31048. Examples of specific small molecule EGFR antagonists include C1-1033 (Pfizer Inc.), which is a quinozaline (N-[4-(3-chloro-4-fluoro-phenylamino)-7-(3-mprpholin-4-yl-propoxy)-quinazolin-6-yl]-acrylamide) inhibitor of tyrosine kinases, particularly EGFR and is described in WO00/31048 at page 8, lines 22-6; PKI166 (Novartis), which is a pyrrolopyrimidine inhibitor of EGFR and is described in WO97/27199 at pages 10-12; GW2016 (GlaxoSmithKline), which is an inhibitor of EGFR and HER2; EKB569 (Wyeth), which is reported to inhibit the growth of tumor cells that overexpress EGFR or HER2 in vitro and in vivo; AG-1478 (Tryphostin), which is a quinazoline small molecule that inhibits signaling from both EGFR and erbB-2; AG-1478 (Sugen), which is a bisubstrate inhibitor that also inhibits protein kinase CK2; PD 153035 (Parke-Davis) which is reported to inhibit EGFR kinase activity and tumor growth, induce apoptosis in cells in culture, and enhance the cytotoxicity of cytotoxic chemotherapeutic agents; SPM-924 (Schwarz Pharma), which is a tyrosine kinase inhibitor targeted for treatment of prostrate cancer; CP-546,989 (OSI Pharmaceuticals), which is reportedly an inhibitor of angiogenesis for treatment of solid tumors; ADL-681, which is a EGFR kinase inhibitor targeted for treatment of cancer; PD 158780, which is a pyridopyrimidine that is reported to inhibit the tumor growth rate of A4431 xenografts in mice; CP-358,774, which is a quinzoline that is reported to inhibit autophosphorylation in HN5 xenografts in mice; ZD1839, which is a quinoline that is reported to have antitumor activity in mouse xenograft models including vulvar, NSCLC, prostrate, ovarian, and colorectal cancers; CGP 59326A, which is a pyrrolopyrimidine that is reported to inhibit growth of EGFR-positive xenografts in mice; PD 165557 (Pfizer); CGP54211 and CGP53353 (Novartis), which are dianilnophthalimides. Naturally derived EGFR tyrosine kinase inhibitors include genistein, herbimycin A, quercetin, and erbstatin. 
         [0063]    Further small molecules reported to inhibit EGFR are tricyclic compounds such as the compounds described in U.S. Pat. No. 5,679,683; quinazoline derivatives such as the derivatives described in U.S. Pat. No. 5,616,582; and indole compounds such as the compounds described in U.S. Pat. No. 5,196,446. 
         [0064]    Further small molecules reported to inhibit EGFR are styryl substituted heteroaryl compounds such as the compounds described in U.S. Pat. No. 5,656,655. The heteroaryl group is a monocyclic ring with one or two heteroatoms, or a bicyclic ring with 1 to about 4 heteroatoms, the compound being optionally substituted or polysubstituted. 
         [0065]    Further small molecules reported to inhibit EGFR are bis mono and/or bicyclic aryl heteroaryl, carbocyclic, and heterocarbocyclic compounds described in U.S. Pat. No. 5,646,153, the compound provided  FIG. 1  of Fry et al., Science 265, 1093-1095 (1994) that inhibits EGFR, tyrphostins that inhibit EGFR/HER1 and HER 2, particularly those in Tables I, II, III, and IV described in Osherov et al., J. Biol. Chem., 25; 268(15):11134-42 (1993), the compound identified as PD166285 that inhibits the EGFR, PDGFR, and FGFR families of receptors, and PD166285, identified as 6-(2,6-dichlorophenyl)-2-(4-(2-diethylaminoethyoxy)phenylamino)-8-methyl-8H-pyrido(2,3-d)pyrimidin-7-one, having the structure shown in  FIG. 1  on page 1436 of Panek et al., Journal of Pharmacology and Experimental Therapeutics 283, 1433-1444 (1997). 
         [0066]    It should be appreciated that useful small molecule to be used in the invention are inhibitors of EGFR, but need not be completely specific for EGFR. As used herein “EGFR inhibitor” can refer to any agent capable of directly or indirectly inhibiting activation of EGFR. This can include compounds that directly inhibit the kinase activity of the EGFR or which inhibit the EGFR signal transduction pathway. In embodiments, an EGFR inhibitor can directly inhibit the kinase activity of the EGFR. In embodiments, the EGFR inhibitor is an antibody specific for EGFR, which can bind at any of the known domains of the receptor including the ligand binding domain or alternate binding sites within the known structure of the receptor. In other embodiments, the EGFR inhibitor is a small molecule, for example an EGFR-selective tyrosine kinase inhibitor. In embodiments an EGFR inhibitor can be Gefitinib (Iressa®) (Astrazeneca), Erlotinib (Tarceva®) (OSI), Cetuximab (Erbitux®) (Merck Serono), Panitumimab (Vectibix®)(Amgen) or other anti-EGFR inhibitors and mixtures thereof. In embodiments, EGFR inhibitors can include EGFR tyrosine kinase inhibitors as would be known in the art. In embodiments the EGRF inhibitor can be Cetuximab (Merck Serono) or Panitumimab (Amgen). In an embodiment the EGFR inhibitor can be Cetuximab (Merck Serono). Cetuximab (IMC-C225) is a chimeric (human/mouse) IgG monoclonal antibody, also known under the tradename ERBITUX. In addition, the agent may target other members of the EGFR receptor family, including the use of Herceptin to target ErbB2 in breast cancer. 
         [0067]    “Chemotherapy” as used herein can include DNA-alkylating agents, antimetabolites, microtubule distrupters, DNA intercalators and hormone therapy. In embodiments, chemotherapy can include but not limited to cisplatin, oxaliplatin, carboplatin, irinotecan, or taxane-therapy, depending on tumour-type that the subject is afflicted with. 
         [0068]    “Antibody” as used herein includes intact immunoglobulin molecules, as well as fragments thereof, such as Fab, F(ab′)2 and Fv, which are capable of binding to an epitope of CXCR1. 
         [0069]    “Tumour”, as used herein, refers to any neoplastic cell growth and proliferation, whether malignant or benign, and all pre-cancerous and cancerous cells and tissues. 
         [0070]    “Cancer” as used herein is a generic name for a wide range of cellular malignancies characterized by unregulated growth, lack of differentiation, and the ability to invade local tissues and metastasize. These neoplastic malignancies can affect various tissues and organs of the body, for example, colorectal cancer, breast cancer, ovarian cancer, lung cancer, prostate cancer, hepatocellular cancer, gastric cancer, pancreatic cancer, cervical cancer, liver cancer, bladder cancer, cancer of the urinary tract, thyroid cancer, renal cancer, carcinoma, melanoma, brain cancer, non-small cell lung cancer, squamous cell cancer of the head and neck, endometrial cancer, multiple myeloma, rectal cancer, and esophageal cancer. In a particular embodiment, the cancer is colorectal cancer. 
         [0071]    The terms “subject” and “patient” are used interchangeably herein to refer to a mammal being assessed for treatment and being treated. In an embodiment, the mammal is a human. 
         [0072]    The terms “treatment”, treating” and the like refer to the administration of an agent for the purpose of obtaining an effect. The effect may be prophylactic and/or may be therapeutic. By “therapeutic” as used herein is meant the abrogation or alleviation of a cancer. This means the survival or life expectancy of the cancer patient will be increased or that one or more symptoms of the cancer are reduced. For example, this can encompass a reduction in the cancer growth rate or tumour volume. Assessment of tumour volume can be by imaging a cancer patient as would be known in the art. 
         [0073]    Each document, reference, patent application or patent cited in this text is expressly incorporated herein in their entirety by reference, which means it should be read and considered by the reader as part of this text. That the document, reference, patent application or patent cited in the text is not repeated in this text is merely for reasons of conciseness. 
         [0074]    Reference to cited material or information contained in the text should not be understood as a concession that the material or information was part of the common general knowledge or was known in any country. 
         [0075]    Throughout the specification, unless the context demands otherwise, the terms ‘comprise’ or ‘include’, or variations such as ‘comprises’ or ‘comprising’, ‘includes’ or ‘including’ will be understood to imply the includes of a stated integer or group of integers, but not the exclusion of any other integer or group of integers. 
     
    
     
         [0076]    An embodiment of the present invention will now be described by way of example only, with reference to the accompanying figures. 
           [0077]      FIG. 1  illustrates Table 1 the characterization of the patient cohort, 
           [0078]      FIG. 2  illustrates Table 2. Multivariate logistic regression for response at 12 weeks, 
           [0079]      FIG. 3  illustrates Table 3. Multivariate logistic regression for response at any time, 
           [0080]      FIG. 4  illustrates Table 4. Univariate survival analysis, 
           [0081]      FIG. 5  illustrates Table 5. Multivariate survival analysis, 
           [0082]      FIG. 6  illustrates survival analysis of patients treated with Cetuximab, randomized for CXCR1 expression levels (18 CXCR1-low, 29 CXCR1-high), 
           [0083]      FIG. 7  illustrates Table 6. Prognostic impact of CXCR1 in Cetuximab-treated patients, 
           [0084]      FIG. 8  illustrates survival analysis of patients who did not receive Cetuximab, randomized for CXCR1 expression levels (35 CXCR1-low, 27 CXCR1-high), 
           [0085]      FIG. 9  illustrates Table 7. Prognostic impact in non-Cetuximab treated patients, 
           [0086]      FIG. 10  illustrates high CXCR1 expression predicts for clinical benefit of adding Cetuximab to oxaliplatin/5-FU chemotherapy (n=55 patients with high CXCR1 expression:), 
           [0087]      FIG. 11  illustrates Table 8. Role of high CXCR1 expression as predictive marker of response to Cetuximab treatment, 
           [0088]      FIG. 12  illustrates Low CXCR1 expression fails to predict the clinical benefit of adding Cetuximab to oxaliplatin/5-FU chemotherapy (38 patients had low CXCR1 expression), and 
           [0089]      FIG. 13  illustrates Table 9. Patient response data to treatment in patients with low CXCR1 expression. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0090]    Based on a national phase III trial which investigated the response of &gt;2500 patients with metastatic colorectal cancer who were randomized to
       chemotherapy alone,   the provision of intermittent chemotherapy, or   chemotherapy in combination with Cetuximab, a monoclonal antibody targeting the EGFR receptor
 
the relationship of CXC-chemokine and CXC-chemokine receptor expression in relation to the clinical response of colorectal cancer to EGFR therapeutics was considered.
       
 
         [0094]    The tissues analysed were obtained from the COIN trial, which was based on provision of chemotherapy (oxaliplatin/5-FU based) and the EGFR-targeted antibody Cetuximab (Merck Serono). 
       Example 1 
     Relationship Between CXCR1 and K-Ras Mutational Status 
       [0095]    In total, 116 tissue samples were obtained from the Central Processing Resource of the COIN phase III clinical trial under ethical consent. Data regarding patient age, gender, K-Ras status, response and patient status was obtained at the time of analysis. Consistent with independent reports regarding the incidence of K-Ras mutations in colorectal cancer, 38% of the tumours in which the status of this protein had been evaluated were found to have a mutation in the protein. Only 10 cases did not have an accompanying characterization of KRas protein. The patient data is presented in Table 1. 
         [0096]    Logistic regression analysis determined that the expression of CXCR1 was independent of K-Ras mutational status in colorectal cancer tissue (P=0.215). 
       Example 2 
     Relationship Between CXCR1 Expression and Tumour Response 
       [0097]    The next analysis was to determine the relationship of clinical parameters in relation to the observation of a Multivariate analysis of data of tumour response in patients, assessed 12 weeks after the onset of treatment, determined that higher CXCR1 expression in the tumour epithelium correlated with an increased tumour response at 12 weeks (p=0.005). In addition, patients treated with Cetuximab had an improved response at 12 weeks if they had high levels of CXCR1 expression (p=0.019). Interestingly, the correlation of response in Cetuximab-treated patients to CXCR1 was more significant than the correlation to KRas-status in this cohort of patients (p=0.053) (Table 2). 
         [0098]    Subsequent multivariate analysis was conducted to analyse parameters against the observation of a clinical response of the patient to treatment at any time. Higher tumour epithelial CXCR1 expression again correlated with the observation of a favourable clinical response (p=0.027) and an increased response in patients treated with Cetuximab (p=0.05). As observed in the analysis of response after 12 weeks, KRas-status was not predictive of response to Cetuximab in this cohort of patients (p=0.099) (Table 3). 
       Example 3 
     Assessment of Clinical Parameters Against the Survival of Patients 
       [0099]    Survival was independent of the Treatment Arm within the trial, while patient age borders on significance. Tumour epithelial CXCR1 expression or the level of CXCL8 expression within the inflammatory infiltrate did not correlate with improved patient survival across the cohort, in univariate analysis. However, high CXCR1 expression did correlate with an improved survival in those patients treated with Cetuximab (p=0.007). In contrast, K-Ras status was not associated with overall survival (p=0.305) or indeed response to Cetuximab (p=0.746) (Table 4). Conduct of a multivariate analysis confirmed that high CXCR1 expression correlated with an improved overall survival in patients treated with Cetuximab (p=0.019) (Table 5). 
       Example 4 
     Prognostic Impact of CXCR1 Expression in Patients Treated with Cetuximab 
       [0100]    Patients were stratified to two cohorts on the basis of high or low CXCR1 expression, which was assessed using the median expression level as the discriminating threshold. Following this stratification, 18 patients who had received Cetuximab were considered to have low CXCR1 expression while 29 patients had high CXCR1 expression. Patients with low CXCR1 expression had a median overall survival of 7.97 months, while patients with high CXCR1 expression had a median overall survival of 19.033 months (p=0.001) ( FIG. 6 ; Table 6). In a parallel assessment conducted in patients who did not receive Cetuximab, there was no difference in the median overall survival of patients with low CXCR1 expression (10.33 months) or high CXCR1 expression (10.73 months) ( FIG. 8 ; Table 7). Together these analyses show the specificity of CXCR1 expression in relation to patient survival in Cetuximab-treated patients. 
       Example 5 
     Capacity of CXCR1 Expression to Predict the Clinical Outcome of Patients to Cetuximab Therapy 
       [0101]    Analysis of patients that had received either chemotherapy alone or chemotherapy in combination with Cetuximab determined low CXCR1 expression in 38 patients, of which 18 patients received Cetuximab in addition to chemotherapy. In patients with low CXCR1 expression, the addition of Cetuximab actually had an adverse effect on the overall survival of these patients, reducing median overall survival from 10.5 months to 7.97 months ( FIG. 12 ; Table 9). 
         [0102]    Analysis of patients with high tumour CXCR1 expression levels had a very different profile. In the 55 patients with high CXCR1 expression, 33 patients received Cetuximab in combination with chemotherapy. In these patients, the addition of Cetuximab improved overall survival from 10.73 months to 18.03 months (p=0.013) ( FIG. 10 ; Table 8). Therefore, this data clearly reveals that high tumour CXCR1 expression predicts for those patients that will derive a clinical benefit from the provision of Cetuximab to an oxaliplatin/5-fluorouracil-based chemotherapy regimen. 
         [0103]    In summary, that analysis indicated the CXCR1 chemokine receptor is a strong prognostic factor and a predictive marker of patient response to Cetuximab in colorectal cancer. 
         [0104]    In the above examples expression of CXCR1 was determined using an optimized immunohistochemistry protocol, exploiting a commercially-available CXCR1 monoclonal antibody). 
         [0105]    Although the invention has been particularly shown and described with reference to particular examples, it will be understood by those skilled in the art that various changes in the form and details may be made therein without departing from the scope of the present invention. 
       Sequence Listing 
       [0106]    The nucleic acid and amino acid sequences of the CXCR1 gene and protein described herein are provided below. Further refinements and/or characterization of additional transcripts that are given the assignment of these gene names are considered to be included under the scope of the claims, and in addition, existing or defined polymorphisms and/or mutations of these genes are included in the definitions of these genes and to be under the scope of the claims filed under this patent application. 
       Molecular Definition of CXCR1 
       [0107]    The nucleotide sequence of CXCR1 is accessible in public databases by the accession number NM — 000634 and is provided herein as SEQ ID NO: 1. In embodiments the term CXCR1 includes active forms of CXCR1 and active fragement thereof. 
         [0000]    
       
         
               
               
             
           
               
                 SEQ ID NO: 1 
                   
               
               
                 tattcatcaa gtgccctcta gctgttaagt cactctgatc tctgactgca gctcctactg 
                   
               
               
                   
               
               
                 ttggacacac ctggccggtg cttcagttag atcaaaccat tgctgaaact gaagaggaca 
               
               
                   
               
               
                 tgtcaaatat tacagatcca cagatgtggg attttgatga tctaaatttc actggcatgc 
               
               
                   
               
               
                 cacctgcaga tgaagattac agcccctgta tgctagaaac tgagacactc aacaagtatg 
               
               
                   
               
               
                 ttgtgatcat cgcctatgcc ctagtgttcc tgctgagcct gctgggaaac tccctggtga 
               
               
                   
               
               
                 tgctggtcat cttatacagc agggtcggcc gctccgtcac tgatgtctac ctgctgaacc 
               
               
                   
               
               
                 tggccttggc cgacctactc tttgccctga ccttgcccat ctgggccgcc tccaaggtga 
               
               
                   
               
               
                 atggctggat ttttggcaca ttcctgtgca aggtggtctc actcctgaag gaagtcaact 
               
               
                   
               
               
                 tctacagtgg catcctgctg ttggcctgca tcagtgtgga ccgttacctg gccattgtcc 
               
               
                   
               
               
                 atgccacacg cacactgacc cagaagcgtc acttggtcaa gtttgtttgt cttggctgct 
               
               
                   
               
               
                 ggggactgtc tatgaatctg tccctgccct tcttcctttt ccgccaggct taccatccaa 
               
               
                   
               
               
                 acaattccag tccagtttgc tatgaggtcc tgggaaatga cacagcaaaa tggcggatgg 
               
               
                   
               
               
                 tgttgcggat cctgcctcac acctttggct tcatcgtgcc gctgtttgtc atgctgttct 
               
               
                   
               
               
                 gctatggatt caccctgcgt acactgttta aggcccacat ggggcagaag caccgagcca 
               
               
                   
               
               
                 tgagggtcat ctttgctgtc gtcctcatct tcctgctttg ctggctgccc tacaacctgg 
               
               
                   
               
               
                 tcctgctggc agacaccctc atgaggaccc aggtgatcca ggagagctgt gagcgccgca 
               
               
                   
               
               
                 acaacatcgg ccgggccctg gatgccactg agattctggg atttctccat agctgcctca 
               
               
                   
               
               
                 accccatcat ctacgccttc atcggccaaa attttcgcca tggattcctc aagatcctgg 
               
               
                   
               
               
                 ctatgcatgg cctggtcagc aaggagttct tggcacgtca tcgtgttacc tcctacactt 
               
               
                   
               
               
                 cttcgtctgt caatgtctct tccaacctct gaaaaccatc gatgaaggaa tatctcttct 
               
               
                   
               
               
                 cagaaggaaa gaataaccaa caccctgagg ttgtgtgtgg aaggtgatct ggctctggac 
               
               
                   
               
               
                 aggcactatc tgggttttgg ggggacgcta taggatgtgg ggaagttagg aactggtgtc 
               
               
                   
               
               
                 ttcaggggcc acaccaacct tctgaggagc tgttgaggta cctccaagga ccggcctttg 
               
               
                   
               
               
                 cacctccatg gaaacgaagc accatcattc ccgttgaacg tcacatcttt aacccactaa 
               
               
                   
               
               
                 ctggctaatt agcatggcca catctgagcc ccgaatctga cattagatga gagaacaggg 
               
               
                   
               
               
                 ctgaagctgt gtcctcatga gggctggatg ctctcgttga ccctcacagg agcatctcct 
               
               
                   
               
               
                 caactctgag tgttaagcgt tgagccacca agctggtggc tctgtgtgct ctgatccgag 
               
               
                   
               
               
                 ctcagggggg tggttttccc atctcaggtg tgttgcagtg tctgctggag acattgaggc 
               
               
                   
               
               
                 aggcactgcc aaaacatcaa cctgccagct ggccttgtga ggagctggaa acacatgttc 
               
               
                   
               
               
                 cccttggggg tggtggatga acaaagagaa agagggtttg gaagccagat ctatgccaca 
               
               
                   
               
               
                 agaaccccct ttacccccat gaccaacatc gcagacacat gtgctggcca cctgctgagc 
               
               
                   
               
               
                 cccaagtgga acgagacaag cagcccttag cccttcccct ctgcagcttc caggctggcg 
               
               
                   
               
               
                 tgcagcatca gcatccctag aaagccatgt gcagccacca gtccattggg caggcagatg 
               
               
                   
               
               
                 ttcctaataa agcttctgtt ccgtgcttgt ccctgtggaa gtatcttggt tgtgacagag 
               
               
                   
               
               
                 tcaagggtgt gtgcagcatt gttggctgtt cctgcagtag aatgggggca gcacctccta 
               
               
                   
               
               
                 agaaggcacc tctctgggtt gaagggcagt gttccctggg gctttaactc ctgctagaac 
               
               
                   
               
               
                 agtctcttga ggcacagaaa ctcctgttca tgcccatacc cctggccaag gaagatccct 
               
               
                   
               
               
                 ttgtccacaa gtaaaaggaa atgctcctcc agggagtctc agcttcaccc tgaggtgagc 
               
               
                   
               
               
                 atcatcttct gggttaggcc ttgcctaggc atagccctgc ctcaagctat gtgagctcac 
               
               
                   
               
               
                 cagtccctcc ccaaatgctt tccatgagtt gcagtttttt cctagtctgt tttccctcct 
               
               
                   
               
               
                 tggagacagg gccctgtcgg tttattcact gtatgtcctt ggtgcctgga gcctactaaa 
               
               
                   
               
               
                 tgctcaataa ataatgatca caggaaaaaa aaaaaaaaaa aa 
               
               
                   
               
               
                 The amino acid sequence of CXCR1 is provided herein as SEQ ID NO: 2. 
               
               
                 MSNITDPQMWDFDDLNFTGMPPADEDYSPCMLETETLNKYVVIIAYALVFLLSLLGNSLV 
               
               
                   
               
               
                 MLVILYSRVGRSVTDVYLLNLALADLLFALTLPIWAASKVNGWIFGTFLCKVVSLLKEVNF 
               
               
                   
               
               
                 YSGILLLACISVDRYLAIVHATRTLTQKRHLVKFVCLGCWGLSMNLSLPFFLFRQAYHPNN 
               
               
                   
               
               
                 SSPVCYEVLGNDTAKWRMVLRILPHTFGFIVPLFVMLFCYGFTLRTLFKAHMGQKHRAM 
               
               
                   
               
               
                 RVIFAVVLIFLLCWLPYNLVLLADTLMRTQVIQESCERRNNIGRALDATEILGFLHSCLNPII 
               
               
                   
               
               
                 YAFIGQNFRHGFLKILAMHGLVSKEFLARHRVTSYTSSSVNVSSNL