Patent Application
20190010553
The present disclosure relates generally to prognosing or classifying a subject with breast cancer. More particularly, the present disclosure relates to methods and devices directed to prognosing or classifying a subject with breast cancer following endocrine treatment using biomarkers.
Despite significant improvements in the treatment of early estrogen receptor positive (ER+) breast cancer, there are ongoing clinical challenges. Targeted anti-endocrine therapies have reduced mortality over the last 30-40 years 1, 2, but ER+disease, which comprises 80% of breast cancers, still leads to the majority of deaths from early breast cancer 3. Multiparametric gene assays are used increasingly to guide clinical treatment decisions 4. Most prognostic tests provide an estimate of relapse risk following the treatment for ER+breast cancer, but still lack predictive value for novel targeted treatment options 2, 4. These multiparametric tests, which include OncotypeDx® (Genomic Health Inc.) 5,6 Prosigna™ (NanoString Technologies, Inc.) 7-9, Mammaprint® (Agendia Inc.) 10, 11, Breast Cancer Index (BioTheranostics Inc.) 12, 13, and EndoPredict (Sividon Diagnostics GmbH) 14, all provide broadly similar clinical utility 15, 16. Although each is derived from RNA abundance studies, there are surprisingly few overlapping genes between different RNA signatures 17. Prat et al., demonstrated in silico that combined signatures may more accurately predict outcome; leading to greater clinical significance 18. Nonetheless, despite a decade of development of multiple residual risk signatures, progress towards stratified or targeted medicine has not been markedly accelerated by these tests. None of the existing tests have identified actionable targets which might form the basis for the next generation of stratified medicine approaches.
In an aspect, there is provided a method of prognosing endocrine-only treatment in a subject with breast cancer, the method comprising: a) providing a tumor sample of the breast cancer; b) determining the expression level of at least 40 of the genes listed in Table 4 in the tumor sample; c) comparing said expression levels to a reference expression level of the group of genes from control samples from a cohort of subjects; and d) determining the residual risk associated with the breast cancer; wherein a statistically significant difference or similarity in the expression of the group of genes compared to the reference expression level corresponds to a residual risk associated with breast cancer.
In an aspect, there is provided a computer-implemented method of prognosing endocrine-only treatment in a subject with breast cancer, the method comprising: a) receiving, at at least one processor, data reflecting the expression level of at least 40 of the genes listed in Table 4 in the tumor sample; b) constructing, at the at least one processor, an expression profile corresponding to the expression levels; c) comparing, at the at least one processor, said expression levels to a reference expression level of the group of genes from control samples from a cohort of subjects; d) determining, at the at least one processor, the residual risk associated with the breast cancer; wherein a statistically significant difference or similarity in the expression of the group of genes compared to the reference expression level corresponds to a residual risk associated with breast cancer.
In an aspect, there is provided a computer program product for use in conjunction with a general-purpose computer having a processor and a memory connected to the processor, the computer program product comprising a computer readable storage medium having a computer mechanism encoded thereon, wherein the computer program mechanism may be loaded into the memory of the computer and cause the computer to carry out the method described herein.
In an aspect, there is provided computer readable medium having stored thereon a data structure for storing the computer program product described herein.
In an aspect, there is provided a device for prognosing or classifying a subject with breast cancer and treated with endocrine therapy, the device comprising: at least one processor; and electronic memory in communication with the at one processor, the electronic memory storing processor-executable code that, when executed at the at least one processor, causes the at least one processor to: a) receive data reflecting the expression level of at least 40 of the genes listed in Table 4 in the tumor sample; b) construct an expression profile corresponding to the expression levels; c) compare said expression levels to a reference expression level of the group of genes from control samples from a cohort of subjects; and d) determining, at the at least one processor, the residual risk associated with the breast cancer wherein a statistically significant difference or similarity in the expression of the group of genes compared to the reference expression level corresponds to a residual risk associated with breast cancer.
In an aspect, there is provided a method of treating a subject with breast cancer, comprising: a) determining the residual risk of a subject according to the method described herein; and b) selecting a treatment based on said residual risk, and preferably treating the subject according to the treatment. In some embodiments, a combination endocrine therapy and chemotherapy is selected as treatment if said patient has a relatively high residual risk in relation to the population median of a reference cohort.
In an aspect, there is provided a composition comprising a plurality of isolated nucleic acid sequences, wherein each isolated nucleic acid sequence hybridizes to: (a) the mRNA of a group of genes corresponding to at least 40 of the genes listed in Table 4; and/or (b) a nucleic acid complementary to a), wherein the composition is used to measure the level of expression of the group of genes.
In an aspect, there is provided an array comprising one or more polynucleotide probes complementary and hybridizable to an expression product of at least 40 of the genes listed in Table 4.
In an aspect, there is provided a kit comprising reagents for detecting mRNA from a sample of a breast cancer tumour of at least one at least 40 of the genes listed in Table 4.
Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures.
Some women with hormone receptor positive early breast cancer can be managed effectively with endocrine therapies alone, whereas for others additional systemic chemotherapy treatment is necessary. The clinical challenges in managing high-risk women are to identify existing and novel drug targets, and to identify those who would benefit from these therapies.
Using the Tamoxifen and Exemestane Adjuvant Multinational Trial (TEAM) pathology cohort19, comprised of 3,825 hormone-receptor positive (ER+ and/or PgR+) cases and including 477 (13%) HER2-positive cases, mRNA abundance analysis was performed to identify a gene signature, for example a 95-gene signature, of residual risk was identified and validated. The 95-gene signature is useful in improving risk stratification in the context of endocrine-treated patients. Moreover, this gene signature can be used to reveal potential drug targets, improving stratification in order to develop targeted therapies for such high-risk patients.
A panel of genes compiled from academic and commercial multiparametric tests as well as genes of importance to breast cancer pathogenesis, was used to profile 3,825 patients. A signature of 95 genes, including nodal status, was validated to stratify endocrine-treated patients into high- and low-risk groups based on distant relapse-free survival (DRFS; HR=5.05, 95% Cl 3.53-7.22, p=7.51×10−22). This risk signature was also found to perform better than current multiparametric tests. When the 95-gene prognostic signature was applied to all patients in the validation cohort, including patients who received adjuvant chemotherapy, the signature remained prognostic (HR=4.76, 95% Cl 3.56-6.2, p=8.87×10−28). Functional gene interaction analyses identified 6 significant modules representing pathways involved in cell cycle control, mitosis and receptor tyrosine signaling; containing a number of genes with existing targeted therapies for use in breast or other malignancies. Thus the identification of high-risk patients using this prognostic signature has the potential to also prioritize patients for treatment with these targeted therapies.
As will become apparent, preferred features and characteristics of one aspect of the invention are applicable to any other aspect of the invention. It should be noted that, as used herein, the singular form “a”, “an” and “the” include plural references unless the context clearly dictates otherwise.
In an aspect, there is provided a method of prognosing endocrine-only treatment in a subject with breast cancer, the method comprising: a) providing a tumor sample of the breast cancer; b) determining the expression level of at least 40 of the genes listed in Table 4 in the tumor sample; c) comparing said expression levels to a reference expression level of the group of genes from control samples from a cohort of subjects; and d) determining a residual risk associated with the breast cancer; wherein a statistically significant difference or similarity in the expression of the group of genes compared to the reference expression level corresponds to the residual risk associated with breast cancer.
The term “subject” as used herein refers to any member of the animal kingdom, preferably a human being and most preferably a human being that has breast cancer or that is suspected of having breast cancer.
The term “sample” as used herein refers to any fluid, cell or tissue sample from a subject which can be assayed for biomarker expression products and/or a reference expression profile, e.g. peptides differentially present in a liquid biopsy.
The term “prognosis” as used herein refers to a clinical outcome group such as a worse survival group or a better survival group associated with a disease subtype which is reflected by a reference profile such as a biomarker reference expression profile or reflected by an expression level of the fifteen biomarkers disclosed herein. The prognosis provides an indication of disease progression and includes an indication of likelihood of death due to cancer. In one embodiment the clinical outcome class includes a better survival group and a worse survival group.
The term “prognosing or classifying” as used herein means predicting or identifying the clinical outcome group that a subject belongs to according to the subject's similarity to a reference profile or biomarker expression level associated with the prognosis. For example, prognosing or classifying comprises a method or process of determining whether an individual with breast cancer has a better or worse survival outcome, or grouping an individual with breast cancer into a better survival group or a worse survival group, or predicting whether or not an individual with breast cancer will respond to therapy.
The term “gene” as used herein means a polynucleotide which may include coding sequences, intervening sequences and regulatory elements controlling transcription and/or translation. Genes include normal alleles of the gene encoding polymorphisms, including silent alleles having no effect on the amino acid sequence of the gene's encoded polypeptide as well as alleles leading to amino acid sequence variants of the encoded polypeptide that do not substantially affect its function. These terms also may optionally include alleles having one or more mutations which affect the function of the encoded polypeptide's function.
The phrase “determining the expression of biomarkers” as used herein refers to determining or quantifying RNA or proteins or protein activities or protein-related metabolites expressed by the biomarkers. The term “RNA” includes mRNA transcripts, and/or specific spliced or other alternative variants of mRNA, including anti-sense products. The term “RNA product of the biomarker” as used herein refers to RNA transcripts transcribed from the biomarkers and/or specific spliced or alternative variants. In the case of “protein”, it refers to proteins translated from the RNA transcripts transcribed from the biomarkers. The term “protein product of the biomarker” refers to proteins translated from RNA products of the biomarkers.
The term “level of expression” or “expression level” as used herein refers to a measurable level of expression of the products of biomarkers, such as, without limitation, the level of micro-RNA, messenger RNA transcript expressed or of a specific exon or other portion of a transcript, the level of proteins or portions thereof expressed of the biomarkers, the number or presence of DNA polymorphisms of the biomarkers, the enzymatic or other activities of the biomarkers, and the level of specific metabolites.
The term “differentially expressed” or “differential expression” as used herein refers to a difference in the level of expression of the biomarkers that can be assayed by measuring the level of expression of the products of the biomarkers, such as the difference in level of mRNA or a portion thereof expressed. In a preferred embodiment, the difference is statistically significant. The term “difference in the level of expression” refers to an increase or decrease in the measurable expression level of a given biomarker, for example as measured by the amount of mRNA as compared with the measurable expression level of a given biomarker in a control.
In certain embodiments, the group of genes is at least 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, or 95 of the genes listed in Table 4.
In some embodiments, the method further comprises building a subject gene expression profile from the determined expression levels of the group of genes.
In some embodiments, determining the residual risk comprises determining a module dysregulation score (MDS) comprising the sum of weights of the group of genes multiplied to a scaled mRNA abundance. In some embodiments, a high MDS score is associated with higher residual risk and/or worse survival and wherein a low MDS score is associated lower residual risk and/or better survival.
As used herein, “overall survival” refers to the percentage of or length of time that people in a study or treatment group are still alive following from either the date of diagnosis or the start of treatment for a disease, such as cancer. In a clinical trial, measuring the overall survival is one way to see how well a new treatment works.
As used herein, “relapse-free survival” refers to, in the case of cancer, the percentage of or length of time that people in a study or treatment group survive without any signs or symptoms of that cancer after primary treatment for that cancer. In a clinical trial, measuring the relapse-free survival is one way to see how well a new treatment works. It is defined as any disease recurrence (local, regional, or distant).
The term “good survival” or “better survival” as used herein refers to an increased chance of survival as compared to patients in the “poor survival” group. For example, the biomarkers of the application can prognose or classify patients into a “good survival group”. These patients are at a lower risk of death after surgery.
The term “poor survival” or “worse survival” as used herein refers to an increased risk of death as compared to patients in the “good survival” group. For example, biomarkers or genes of the application can prognose or classify patients into a “poor survival group”. These patients are at greater risk of death or adverse reaction from disease or surgery, treatment for the disease or other causes.
In some embodiments, the method further comprises normalizing said mRNA abundance using at least one control, preferably a plurality of controls.
In some embodiments, at least one of the plurality of controls comprises mRNA abundance of reference genes of a reference subject or the subject.
A “control population” refers to a defined group of individuals or a group of individuals with or without cancer, and may optionally be further identified by, but not limited to geographic, ethnic, race, gender, one or more other conditions or diseases, and/or cultural indices. In most cases a control population may encompass at least 10, 50, 100, 1000, or more individuals.
“Positive control data” encompasses data representing levels of RNA encoded by a target gene of the invention in each of one or more subjects having cancer of the invention, and encompasses a single data point representing an average level of RNA encoded by a target gene of the invention in a plurality of subjects having cancer of the invention.
“Negative control data” encompasses data representing levels of RNA encoded by a target gene of the invention in each of one or more subjects not having cancer of the invention, and encompasses a single data point representing an average level of RNA encoded by a target gene of the invention in a plurality of subjects having cancer of the invention.
The probability that test data “corresponds” to positive control data or negative control data refers to the probability that the test data is more likely to be characteristic of data obtained in subjects having breast cancer than in subjects not breast cancer, or is more likely to be characteristic of data obtained in subjects not having breast cancer or response to treatment than in subjects having breast cancer response to treatment, respectively.
In some embodiments, the method further comprises comparing a clinical indicator of the subject to a plurality of reference clinical indicators, wherein the clinical indicator comprises at least one of age, tumor grade, pathological tumor size or nodal status, preferably nodal status, and fitting these clinical indicators on the MDS, preferably using a multivariate Cox proportional hazards model.
Patients with a high risk prognosis therefore may benefit from more aggressive therapy, e.g. adjuvant therapy, in addition to hormone therapy. Adjuvant therapy may include chemotherapy, radiation therapy, hormone therapy, targeted therapy, or biological therapy.
In some embodiments, the method further comprises treating the subject with combined endocrine therapy and chemotherapy if the subject has a relatively high residual risk in relation to the population median of a reference cohort.
In some embodiments, the breast cancer is hormone receptor positive (ER+).
In some embodiments, the expression levels are determined using NanoString®.
In some embodiments, the residual risk represents distant relapse-free survival.
In an aspect, there is provided a method of treating a subject with breast cancer, comprising: a) determining the residual risk of a subject according to the method described herein; and b) selecting a treatment based on said residual risk, and preferably treating the subject according to the treatment. In some embodiments, a combination endocrine therapy and chemotherapy is selected as treatment if said patient has a relatively high residual risk in relation to the population median of a reference cohort.
In an aspect, there is provided a computer-implemented method of prognosing endocrine-only treatment in a subject with breast cancer, the method comprising: a) receiving, at at least one processor, data reflecting the expression level of at least 40 of the genes listed in Table 4 in the tumor sample; b) constructing, at the at least one processor, an expression profile corresponding to the expression levels; c) comparing, at the at least one processor, said expression levels to a reference expression level of the group of genes from control samples from a cohort of subjects; d) determining, at the at least one processor, a residual risk associated with the breast cancer; wherein a statistically significant difference or similarity in the expression of the group of genes compared to the reference expression level corresponds to the residual risk associated with breast cancer.
As used herein, “processor” may be any type of processor, such as, for example, any type of general-purpose microprocessor or microcontroller (e.g., an Intel™ x86, PowerPC™, ARM™ processor, or the like), a digital signal processing (DSP) processor, an integrated circuit, a field programmable gate array (FPGA), or any combination thereof.
As used herein “memory” may include a suitable combination of any type of computer memory that is located either internally or externally such as, for example, random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), or the like. Portions of memory 102 may be organized using a conventional filesystem, controlled and administered by an operating system governing overall operation of a device.
As used herein, “computer readable storage medium” (also referred to as a machine-readable medium, a processor-readable medium, or a computer usable medium having a computer-readable program code embodied therein) is a medium capable of storing data in a format readable by a computer or machine. The machine-readable medium can be any suitable tangible, non-transitory medium, including magnetic, optical, or electrical storage medium including a diskette, compact disk read only memory (CD-ROM), memory device (volatile or non-volatile), or similar storage mechanism. The computer readable storage medium can contain various sets of instructions, code sequences, configuration information, or other data, which, when executed, cause a processor to perform steps in a method according to an embodiment of the disclosure. Those of ordinary skill in the art will appreciate that other instructions and operations necessary to implement the described implementations can also be stored on the computer readable storage medium. The instructions stored on the computer readable storage medium can be executed by a processor or other suitable processing device, and can interface with circuitry to perform the described tasks.
As used herein, “data structure” a particular way of organizing data in a computer so that it can be used efficiently. Data structures can implement one or more particular abstract data types (ADT), which specify the operations that can be performed on a data structure and the computational complexity of those operations. In comparison, a data structure is a concrete implementation of the specification provided by an ADT.
Embodiments of the disclosure can be represented as a computer program product stored in a machine-readable medium (also referred to as a computer-readable medium, a processor-readable medium, or a computer usable medium having a computer-readable program code embodied therein). The machine-readable medium can be any suitable tangible, non-transitory medium, including magnetic, optical, or electrical storage medium including a diskette, compact disk read only memory (CD-ROM), memory device (volatile or non-volatile), or similar storage mechanism. The machine-readable medium can contain various sets of instructions, code sequences, configuration information, or other data, which, when executed, cause a processor to perform steps in a method according to an embodiment of the disclosure. Those of ordinary skill in the art will appreciate that other instructions and operations necessary to implement the described implementations can also be stored on the machine-readable medium. The instructions stored on the machine-readable medium can be executed by a processor or other suitable processing device, and can interface with circuitry to perform the described tasks.
In some embodiments, the processor determines the residual risk by calculating a module dysregulation score (MDS) comprising the sum of weights of the group of genes multiplied to the scaled mRNA abundance.
In some embodiments, a high MDS score is associated with higher residual risk and/or worse survival and wherein a low MDS score is associated lower residual risk and/or better survival.
In some embodiments, the processor further normalizes said mRNA abundance using at least one control, preferably a plurality of controls.
In some embodiments, at least one of the plurality of controls comprises mRNA abundance of reference genes of a reference subject or the subject.
In some embodiments, the processor further compares a clinical indicator of the subject to a plurality of reference clinical indicators, wherein the clinical indicator comprises at least one of age, tumor grade, pathological tumor size or nodal status, preferably nodal status, and fits these clinical indicators on the MDS, preferably using a multivariate Cox proportional hazards model.
In some embodiments, the method further comprises outputting a suggestion for treating the subject with combined endocrine therapy and chemotherapy if the subject has a relatively high residual risk in relation to the population median of a reference cohort.
In some embodiments, the breast cancer is hormone receptor positive (ER+).
In some embodiments, the residual risk represents distant relapse-free survival.
In an aspect, there is provided a computer program product for use in conjunction with a general-purpose computer having a processor and a memory connected to the processor, the computer program product comprising a computer readable storage medium having a computer mechanism encoded thereon, wherein the computer program mechanism may be loaded into the memory of the computer and cause the computer to carry out the method described herein.
In an aspect, there is provided computer readable medium having stored thereon a data structure for storing the computer program product described herein.
In an aspect, there is provided a device for prognosing or classifying a subject with breast cancer and treated with endocrine therapy, the device comprising: at least one processor; and electronic memory in communication with the at one processor, the electronic memory storing processor-executable code that, when executed at the at least one processor, causes the at least one processor to: a) receive data reflecting the expression level of at least 40 of the genes listed in Table 4 in the tumor sample; b) construct an expression profile corresponding to the expression levels; c) compare said expression levels to a reference expression level of the group of genes from control samples from a cohort of subjects; and d) determining, at the at least one processor, a residual risk associated with the breast cancer wherein a statistically significant difference or similarity in the expression of the group of genes compared to the reference expression level corresponds to the residual risk associated with breast cancer.
In an aspect, there is provided a composition comprising a plurality of isolated nucleic acid sequences, wherein each isolated nucleic acid sequence hybridizes to: (a) the mRNA of a group of genes corresponding to at least 40 of the genes listed in Table 4; and/or (b) a nucleic acid complementary to a), wherein the composition is used to measure the level of expression of the group of genes.
In an aspect, there is provided an array comprising one or more polynucleotide probes complementary and hybridizable to an expression product of at least 40 of the genes listed in Table 4.
In an aspect, there is provided a kit comprising reagents for detecting mRNA from a sample of a breast cancer tumour of at least one at least 40 of the genes listed in Table 4.
Examples of primers include an oligonucleotide which is capable of acting as a point of initiation of polynucleotide synthesis along a complementary strand when placed under conditions in which synthesis of a primer extension product which is complementary to a polynucleotide is catalyzed. Such conditions include the presence of four different nucleotide triphosphates or nucleoside analogs and one or more agents for polymerization such as DNA polymerase and/or reverse transcriptase, in an appropriate buffer (“buffer” includes substituents which are cofactors, or which affect pH, ionic strength, etc.), and at a suitable temperature. A primer must be sufficiently long to prime the synthesis of extension products in the presence of an agent for polymerase. A typical primer contains at least about 5 nucleotides in length of a sequence substantially complementary to the target sequence, but somewhat longer primers are preferred. A primer will always contain a sequence substantially complementary to the target sequence, that is the specific sequence to be amplified, to which it can anneal.
The terms “complementary” or “complement thereof”, as used herein, refer to sequences of polynucleotides which are capable of forming Watson & Crick base pairing with another specified polynucleotide throughout the entirety of the complementary region. This term is applied to pairs of polynucleotides based solely upon their sequences and does not refer to any specific conditions under which the two polynucleotides would actually bind
The term “probe” refers to a molecule which can detectably distinguish between target molecules differing in structure, such as allelic variants. Detection can be accomplished in a variety of different ways but preferably is based on detection of specific binding. Examples of such specific binding include antibody binding and nucleic acid probe hybridization.
The term “hybridize” or “hybridizable” refers to the sequence specific non-covalent binding interaction with a complementary nucleic acid. In a preferred embodiment, the hybridization is under high stringency conditions. Appropriate stringency conditions which promote hybridization are known to those skilled in the art, or can be found in Current Protocols in Molecular Biology, John Wiley & Sons, N.Y. (1989), 6.3.1 6.3.6. For example, 6.0× sodium chloride/sodium citrate (SSC) at about 45° C., followed by a wash of 2.0×SSC at 50° C. may be employed.
The polynucleotide compositions can be primers, can be cDNA, can be RNA, can be DNA complementary to target cDNA or a portion thereof, genomic DNA, unspliced RNA, spliced RNA, alternately spliced RNA, synthetic forms, and mixed polymers, both sense and antisense strands, and may be chemically or biochemically modified or may contain non-natural or derivatized nucleotide bases, as will be readily appreciated by those skilled in the art.
Where nucleic acid includes RNA, reference to the sequence shown should be construed as reference to the RNA equivalent, with U substituted for T.
The methods of nucleic acid isolation, amplification and analysis are routine for one skilled in the art and examples of protocols can be found, for example, in the Molecular Cloning: A Laboratory Manual (3-Volume Set) Ed. Joseph Sambrook, David W. Russel, and Joe Sambrook, Cold Spring Harbor Laboratory; 3rd edition (Jan. 15, 2001), ISBN: 0879695773. Particularly useful protocol source for methods used in PCR amplification is PCR (Basics: From Background to Bench) by M. J. McPherson, S. G. Moller, R. Beynon, C. Howe, Springer Verlag; 1st edition (Oct. 15, 2000), ISBN: 0387916008.
Examples of amplification techniques include strand displacement amplification, as disclosed in U.S. Pat. No. 5,744,311; transcription-free isothermal amplification, as disclosed in U.S. Pat. No. 6,033,881; repair chain reaction amplification, as disclosed in WO 90/01069; ligase chain reaction amplification, as disclosed in European Patent Appl. 320 308; gap filling ligase chain reaction amplification, as disclosed in U.S. Pat. No. 5,427,930; and RNA transcription-free amplification, as disclosed in U.S. Pat. No. 6,025,134.
“Kit” refers to a combination of physical elements, e.g., probes, including without limitation specific primers, labeled nucleic acid probes, antibodies, protein-capture agent(s), reagent(s), instruction sheet(s) and other elements useful to practice the invention, in particular to identify the levels of particular RNA molecules in a sample. These physical elements can be arranged in any way suitable for carrying out the invention. For example, probes and/or primers can be provided in one or more containers or in an array or microarray device.
In one embodiment, levels of RNA encoded by a target gene can be determined in one analysis. A combination kit may therefore include primers capable of amplifying cDNA derived from RNA encoded by different target genes. The primers may be differentially labeled, for example using different fluorescent labels, so as to differentiate between RNA from different target genes.
Multiplex, such as duplex, real-time RT-PCR enables simultaneous quantification of 2 targets in the same reaction, which saves time, reduces costs, and conserves samples. These advantages of multiplex, real-time RT-PCR make the technique well-suited for high-throughput gene expression analysis. Multiplex qPCR assay in a real-time format facilitates quantitative measurements and minimizes the risk of false-negative results. It is essential that multiplex PCR is optimized so that amplicons of all samples are compared insub-plateau phase of PCR. Yun, Z., I. Lewensohn-Fuchs, P. Ljungman, L. Ringholm, J. Jonsson, and J. Albert. 2003. A real-time TaqMan PCR for routine quantitation of cytomegalovirus DNA in crude leukocyte lysates from stem cell transplant patients. J. Virol. Methods 110:73-79. [PubMed]. Yun, Z., I. Lewensohn-Fuchs, P. Ljungman, and A. Vahlne. 2000. Real-time monitoring of cytomegalovirus infections after stem cell transplantation using the TaqMan polymerase chain reaction assays. Transplantation 69:1733-1736. [PubMed]. Simultaneous quantification of up to 2, 3, 4, 5, 6, 7, and 8 or more targets may be useful.
For example, the primers and probes contained within the kit may include those able to recognize any of genes of the 95 gene signature described herein.
A primer which “selectively hybridizes” to a target polynucleotide is a primer which is capable of hybridizing only, or mostly, with a single target polynucleotide in a mixture of polynucleotides consisting of RNA in a sample, or consisting of cDNA complementary to RNA within the sample.
A gene expression profile for breast cancer found in a sample at the RNA level of one or more genes comprising, but preferably not limited to, any of the 95 genes described herein, can be identified or confirmed using many techniques, including but preferably not limited to PCR methods, as for example discussed further in the working examples herein, Northern analyses and the microarray technique, NanoString® and quantitative sequencing. This gene expression profile can be measured in a sample, using various techniques including e.g. microarray technology. In an embodiment of this method, fluorescently labeled cDNA probes may be generated through incorporation of fluorescent nucleotides by reverse transcription of RNA extracted from a sample. Labeled cDNA probes applied to the chip hybridize with specificity to each spot of DNA on the array. Quantitation of hybridization of each arrayed element allows for assessment of corresponding mRNA abundance. For example, with dual color fluorescence, separately labeled cDNA probes generated from two sources of RNA are hybridized pair wise to the array. The relative abundance of the transcripts from the two sources corresponding to each specified gene is thus determined simultaneously. Such methods have been shown to have the sensitivity required to detect rare transcripts, which are expressed at a few copies per cell, and to reproducibly detect at least approximately two-fold differences in the expression levels (Schena et al., Proc. Natl. Acad. Sci. USA 93(2):106-149 (1996)). Microarray analysis can be performed by commercially available equipment, following manufacturer's protocols, such as by using the Affymetrix GenChip technology, or Incyte's microarray technology.
In the present description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to one skilled in the art that these specific details are not required. For example, specific details are not provided as to whether the embodiments described herein are implemented as a software routine, hardware circuit, firmware, or a combination thereof.
The above listed aspects and/or embodiments may be combined in various combinations as appreciated by a person of skill in the art. The advantages of the present disclosure are further illustrated by the following examples. The examples and their particular details set forth herein are presented for illustration only and should not be construed as a limitation on the claims of the present invention.
The TEAM trial was a multinational, open-label, phase III trial in which postmenopausal women with hormone receptor-positive19 early breast cancer were randomly assigned to receive Exemestane (25 mg) once daily, or Tamoxifen (20 mg) once daily for the first 2.5-3 years; followed by Exemestane (25 mg) (totaling 5 years of treatment) (see
The TEAM trial included a pathology research study comprised of 4,736 patients from five countries with an average clinical follow-up of 6.86 years. Power analysis was performed to confirm the study size had 88.6% and 100% power to detect a HR of at least 3.0 in the training and validation cohorts respectively (see
To evaluate whether there was sufficient power to develop prognostic markers in this study, power calculations were performed for both endocrine-only cohort, as well as the endocrine+adjuvant chemotherapy cohort; the complete TEAM cohort (n=2549 and events=320; n=3,825 and events=507); and for each of the training (n=576 and events=67; n=790 and events=106) and validation (n=1973 and events=253; n=3,035 and events=431) subsets separately. Assuming equal-sized patient groups, power estimates representing the likelihood of observing a specific HR against the above-mentioned event numbers were derived using the formula (1) below 37:
where E represents the total number of events (DRFS) and a represents the significance level which was set to 10−3 to represent multiple testing adjustment. zpower was calculated for HR ranging from 1 to 3 with steps of 0.0138 (Haider et al. submitted).
Five 4 μm formalin-fixed paraffin-embedded (FFPE) sections per case were deparaffinised, tumor areas were macro-dissected and RNA extracted using the Ambion® Recoverall™ Total Nucleic Acid Isolation Kit-RNA extraction protocol (Life Technologies™, Ontario, Canada). RNA aliquots were quantified using a Nanodrop-8000 spectrophometer (Delaware, USA). All 3825 RNAs extracted from the TEAM pathology cohort were successfully assayed. Probes for each gene were designed and synthesised at NanoString® Technologies (Seattle, Wash., USA); and 250 ng of RNA for each sample were hybridised, processed and analysed using the NanoString® nCounter® Analysis System, according to NanoString® Technologies protocols.
mRNA Abundance Analysis and Survival Modelling
Raw mRNA abundance count data were pre-processed using the NanoStringNorm R package 33,39 (v1.1.19) using normalization factors derived from the geometric mean of the top expressing 75 genes. Samples with RNA content |z-score|>6 were flagged and removed as outliers. To assess the performance of the chosen normalization method in this cohort, a total of 252 combination of preprocessing methods were evaluated: spanning normalization methods that make use of six positive controls, eight negative controls and eight housekeeping genes (RPLP0, TFRC, MRPL19, SF3A1, GAPDH, PSMC4, ACTB, and GUS) followed by global normalization (see
Univariate survival analysis of preprocessed mRNA abundance data was performed by median-dichotomizing patients into high- and low-expression groups. Clinical variable age was modeled as binary (dichotomized around age 55), while grade and nodal status were modelled as ordinal variables, and pathological size was modeled as a continuous variable.
Feature-selection of genes was first performed based on univariate Cox proportional hazards modelling in the endocrine-treated only training cohort; those with p<0.25 were retained. These retained genes were used to calculate a “module-dysregulation score”.
Module dysregulation scores (MDS) were calculated using the following process (Haider et al., submitted): 1) weights (β) of all evaluated genes were calculated by fitting a univariate Cox proportional hazards model based on the Training cohort only; and 2) these weights were then multiplied to the scaled mRNA abundance levels to estimate per-patient module dysregulation score as represented by formula (2):
Here, n represents the number of genes in a given module and Xi represents the scaled (z-score) abundance of gene i. MDS for patients in the Validation cohort were generated using parameters estimated through the Training cohort.
A multivariate Cox proportional hazards model was then fit on MDSs, along with clinical covariates (age, grade, pathological size and nodal status); a stepwise backward selection approach using AIC was performed to refine the multivariate model. The final selected model was trained in the training cohort and validated in the fully independent validation cohort (see Table 1). DRFS truncated to 10 years was used as an end-point. Recurrence probabilities were estimated as described below. All survival modelling was performed on DRFS, in the R statistical environment with the survival package (v2.37-4). Model performances were evaluated through area under the receiver operating characteristic (ROC) curve (AUC).
Recurrence probabilities at 5- and 10-years were estimated by splitting the predicted risk-scores in 25 equal bins. For each bin, recurrence probability R(t) was calculated as 1-S(t), where S(t) is the Kaplan-Meier survival estimate at year 5 or year 10. A local polynomial regression was used to smooth the R(t) estimates of these 25 bin. The predicted estimates were then plotted against the median risk score of each group except the first and last group, where the lowest risk score and 99th percentile were used, respectively. All survival modelling was performed in the R statistical environment (R package: survival v 2.38-3).
Performance of survival models was evaluated using the area under the receiver operating characteristic (ROC) curve. A permutation analysis was performed to evaluate the significance of AUC differences across the different models (scores were shuffled 10,000 times while preserving the order of the survival objects).
The derivation of similar risk classifications using genes comprising the following multi-parametric tests OncotypeDx® (Genomic Health Inc.)5, 6, Prosigna™ (NanoString Technologies, Inc.) 7-9, Mammaprint® (Agendia Inc.) 10, 11.
mRNA-IHC4 Risk Score:
IHC4-protein model risk scores were calculated as described 41, 42 and adjusted for clinical covariates. ER10 scores were calculated by dividing ER histoscores by 30 and PgR10 scores were calculated by dividing the percent PgR staining by 10. A 10-fold cross validation approach was used to train the model and generate IHC4 RNA risk scores. An mRNA-IHC4 model was trained on mRNA abundance profiles of ESR1, PGR, ERBB2 and MKI67 in the training cohort using multivariate Cox proportional hazards modelling (Table 2). Model predictions (continuous risk scores) were grouped into quartiles and analysed using Kaplan-Meier analysis and multivariate Cox proportional hazards model adjusted for clinical variables as above.
OncotypeDX-Like Recurrence Score:
Data from the 16 test genes were normalized as previously described 43 and NanoString intensity values log 2 transformed to fit the 0-15 measurement range from the original publication. Unscaled recurrence scores were then calculated based on: RSU=+0.47×GRB7 group score−0.34× ER group score+1.04× proliferation group score+0.10× invasion group score+0.05× CD68−0.08×GSTM1−0.07×BAG1; and finally the scores are scaled as previously described 43 Patients were then classified into high or low outcome groups based on a recurrence score of above or below 25, respectively; and modeled for DRFS.
Prosigna-Like Subtyping and Risk of Recurrence Score:
Samples were scored based on the method outlined by Parker et al.44 and trained in the context of ER-positivity, using the 50 genes of the PAM50 gene list 45-47. The “normal-like” subgroup was removed from the final subtyping classification. R scripts were obtained from the supplementary files 44 and scores were generated which were then modelled against DRFS.
MammaPrint-Like Risk Score:
Samples were scored based on the gene70 function of the genefu R package (v1.14.0). Derivation of low and high-risk categories were modelled according to van de Vijver et al. 48 and outcome based on DRFS.
Genomic Grade Index-Like Risk Modelling:
Samples were scored based on the procedure outlined in Toussaint et al.49 using MYBL2, KPNA2, CDC2 and CDC20. Expression data was used to calculate average expression housekeeping genes (GUS, TBP, RPLPO and TFRC), which was used to normalize the expression of the four genes used to determine the GGI score. Patients were classified into low or high risk groups and modelled for DRFS. Genomic Grade Index 34; in addition to IHC4 35, 36 are described previously by Prat et al., 18 and in Table 2.
The final gene list was loaded into the Cytoscape Reactome Functional Interaction (FI) plugin in Cytoscape (v3.0.2). Symbols were loaded as a gene set with the 2013 version of the FI network. A FI network was constructed with FI annotations and no linker genes. Spectral clustering and Pathway Enrichment were computed for each module using the Reactome FI plugin functions.
The RNA abundance profiles of all genes were generated for 3,825 patients. Of patients who had complete therapy information, 2,549 were treated with endocrine therapies alone, while 1,275 also received adjuvant chemotherapy. The endocrine-treated only patients were divided into a 576-patient training cohort (n=67 events), and a 1,973-patient validation cohort (n=253 events), which was used for signature discovery and validation, respectively. To test the prognostic ability of the signature, which was trained and validated in the endocrine-treated patients, to patients who were treated with adjuvant chemotherapy, the signature was then modeled against all patients in the validation cohort and adjusted for adjuvant chemotherapy (n=3,035). The median follow-up in each cohort was 7.51 and 6.21 years respectively. The clinical characteristics of the endocrine-treated training and validation cohorts are described in Table 1. The clinical characteristics of the entire cohort of 3,825 patients are summarized in Table 3. High tumor grade, nodal status, pathological size and HER2 IHC status were univariately prognostic in both training and validation cohorts (see Table 1 and Table 3).
Univariate assessment of the original gene list of 165 genes identified 95 genes which were prognostically significant in the endocrine only-treated patients (Table 4, see
To determine whether the 95-gene residual signature continued to be prognostic amongst patients who also received adjuvant chemotherapy, the model was applied to all patients in the validation cohort (with and without chemotherapy), but stratified to chemotherapy (see
Performance of the 95-Gene Signature of Residual Risk when Adjusted for HER2 Status
To determine whether the 95-gene residual risk signature remained prognostic in both HER2-positive and HER2-negative patients, the model was applied to patients in the validation cohort who did not receive any additional adjuvant chemotherapy and results stratified by HER2-status (see
Using the NanoString RNA abundance data, risk scores from current multiparametric test were generated and are summarized in
Performance of the 95-gene Residual Risk Signature and Multi-Parametric Tests:
The composition of the gene list enabled the derivation of similar risk classifications representing a number of commercial and academic residual risk stratification tests (see
Prosigna-Like Risk of Recurrence Scores and Molecular Subtyping:
Using the genes comprising the Prosigna test, 1971 patients across the endocrine-only treated validation cohort n=194 were identified as being low risk; n=744 were identified as having intermediate risk; and n=1033 identified as being high risk (see Table 5,
OncotypeDx-Like Risk Score:
OncotypeDx-like risk scores were generated according to Paik et al. 43. In keeping with the cut-off used in the TAILORx study 50, 51, patients were dichotomized into low- or high-risk groups using a risk score of 25 as the cut-off (see
MammaPrint-Like Risk Assessment:
MammaPrint-like risk assessment identified 1125 (57.0%) patients across the endocrine only treated cohort identified as being low risk; and 848 (43%) identified as being high risk. DRFS was longer for low-risk patients and shorter for MammaPrint-like high-risk patients (HRhigh=3.63, 95% Cl 2.77-4.77, p=1.66×10−20, see
Genomic Grade Index-Like Risk Modelling:
When patients were stratified according to the Genomic Grade Index using 995 patients (50.4%) were identified as low risk with the remaining 1018 patients (49.6%) deemed high risk (HRhigh=3.12, 95% Cl 2.34-4.15, p=7.51×10−15) see
IHC4-mRNA Risk Assessment:
Conversion of the protein-based residual risk classifier, IHC4 using the expression values of ER, PgR, Ki67 and HER2 within the code set resulted in 569 (28.8%) patients identified as low-risk and 1404 (71.2%) patients identified as high-risk within the endocrine-only treated patients. DFRS for endocrine-only treated patients deemed low-risk by IHC4-mRNA was longer than those deemed as high-risk (HRhigh=3.48, 95% Cl 2.35-5.15, p=5.11×10−10, see
Six significant network modules were identified using the Reactome Functional Interaction (FI) tool, comprising 52 of 95 genes in the signature (see
These differences were found to be statistically significant (Table 9). As individual modules, they were statistically significant predictors of outcome (see
Using the Integrity Compound Search (Thomson Reuters) for the genes within these modules, a number of targeted compounds were identified as being currently used in the clinic for treatment of breast cancer or other neoplasms; or in phase II and/or phase III development (https://clinicaltrials.gov/) (see
Relapse following endocrine treatment remains a significant clinical challenge, as more women die following treatment for ER+disease than for any other breast cancer subtype 3. Therefore, there is an ongoing need to identify women who are at risk for relapse following endocrine therapy. More importantly, simultaneously identifying targets for future therapeutic intervention and the means to effectively stratify women to such targeted therapies will improve the clinical management of these patients, and potentially reducing their overtreatment, or conversely identifying patients who may be currently undertreated. Using 3825 patients from the TEAM pathology cohort, a signature was derived that both significantly improves risk stratification and identifies genes for which there are drugs currently in use, or under evaluation (https://clinicaltrials.gov/) in other malignancies. These patients could potentially be matched to the specific functional modules within this 95 gene signature (Table 10, Table 11). As alluded to by the prognostic capacity of the individual modules (see
While current multiparametric tests can identify those who may benefit from current adjuvant chemotherapy regimens, none of these tests predicts response to a drug-specific chemotherapy. This challenge is hampered by the identification of driver pathways in addition to the complexities of both global and individual chemotherapeutic response. Using the information generated by this data, a model for the examination and validation of candidate drugs which target the gene modules comprising the 95-gene signature (see
In this way, genes associated with the G2/M checkpoint, as identified in Module 1, such as BIRC5 (Survivin), could be targeted. YM155, a Survivin suppressor, was evaluated in the metastatic breast cancer setting in combination with docetaxel in a phase II, multicenter, open-label, 2-arm study 20. However, in that study, the lack of up-front patient stratification for YM155 benefit likely contributed to the finding of no significant benefit in its addition to Docetaxel, thus obscuring the potential benefit of targeting this pathway. While known to be overexpressed in breast cancers, the relatively higher expression of BIRC5 observed among the high-risk patients (p=7.23×10−180) (Table 9) suggests there is a tipping point of mRNA abundance leading to increased risk. All genes within Modules 1, 3 and 4 were observed to show a higher expression among patients at higher risk for relapse which were statistically significant (Table 9), reflecting the prominent role of cell cycle and proliferation in breast cancer pathogenesis.
Module 3 is characterized by pathways involving late mitotic events. The overexpression of CDK1 offers a theranostic target, with the use of Dinacilib or similar molecules, currently under evaluation in phase III trials (Table 11). Regaining cell cycle and mitotic checkpoint control is another attractive mechanism for directed therapies, with theranostic targets such as PLK1 (see
However, with 33.8% of HER2-enriched-like patients possessing confirmed HER2 gene amplification or protein over-expression, these results suggest some patients may benefit from therapy targeting the ERBB-family and associated pathways. In fact, the 95-gene signature was still prognostic irrespective of ERBB2/HER2-status, in this population of patients that pre-dates the use of anti-ERBB2/HER2 therapies (see
It was demonstrated that a 95-gene signature of residual risk, which integrates nodal status, has significantly better clinical utility for early recurrence than the currently available multiparametric tests. This signature appears to remain prognostic for later recurrence. Unlike these multiparametric tests, modular analysis of the genes in the signature, have identified several genes and pathways suitable for therapeutic intervention among the high-risk patients. There is a need for significant improvement in the targeted selection of patients suitable for new therapies, rather than the randomization of all-comers in future clinical trial design.
Hormone-receptor positive cancers are molecularly heterogeneous, thus requiring novel treatment strategies (see
Although preferred embodiments of the invention have been described herein, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims. All documents disclosed herein, including those in the following reference list, are incorporated by reference.
This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/263,805 filed Dec. 7, 2015, which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2016/000304 | 12/7/2016 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62263805 | Dec 2015 | US |
