Patent Application
20100086935
The present invention relates to use of gene expression data, and in particular to use of gene expression data in identification, monitoring and treatment of disease and in characterization of biological condition of a subject.
The prior art has utilized gene expression data to determine the presence or absence of particular markers as diagnostic of a particular condition, and in some circumstances have described the cumulative addition of scores for over expression of particular disease markers to achieve increased accuracy or sensitivity of diagnosis. Information on any condition of a particular patient and a patient's response to types and dosages of therapeutic or nutritional agents has become an important issue in clinical medicine today not only from the aspect of efficiency of medical practice for the health care industry but for improved outcomes and benefits for the patients.
In a first embodiment, there is provided a method, for evaluating a biological condition of a subject, based on a sample from the subject. The method includes: deriving from the sample a profile data set, the profile data set including a plurality of members, each member being a quantitative measure of the amount of a distinct RNA or protein constituent in a panel of constituents selected so that measurement of the constituents enables evaluation of the biological condition; and
in deriving the profile data set, achieving such measure for each constituent under measurement conditions that are substantially repeatable.
There is a related embodiment for providing an index that is indicative of the state of a subject, as to a biological condition, based on a sample from the subject. This embodiment includes:
deriving from the sample a profile data set, the profile data set including a plurality of members, each member being a quantitative measure of the amount of a distinct RNA or protein constituent in a panel of constituents selected so that measurement of the constituents enables evaluation of the biological condition; and
in deriving the profile data set, achieving such measure for each constituent under measurement conditions that are substantially repeatable; and
applying values from the profile data set to an index function that provides a mapping from an instance of a profile data set into a single-valued measure of biological condition, so as to produce an index pertinent to the biological condition of the subject.
In further embodiments related to the foregoing, there is also included, in deriving the profile data set, achieving such measure for each constituent under measurement conditions wherein specificity and efficiencies of amplification for all constituents are substantially similar. Similarly further embodiments include alternatively or in addition, in deriving the profile data set, achieving such measure for each constituent under measurement conditions wherein specificity and efficiencies of amplification for all constituents are substantially similar.
In embodiments relating to providing the index a further embodiment also includes providing with the index a normative value of the index function, determined with respect to a relevant population, so that the index may be interpreted in relation to the normative value.
Optionally providing the normative value includes constructing the index function so that the normative value is approximately 1. Also optionally, the relevant population has in common a property that is at least one of age group, gender, ethnicity, geographic location, diet, medical disorder, clinical indicator, medication, physical activity, body mass, and environmental exposure.
In another related embodiment, efficiencies of amplification, expressed as a percent, for all constituents lie within a range of approximately 2 percent, and optionally, approximately 1 percent.
In another related embodiment, measurement conditions are repeatable so that such measure for each constituent has a coefficient of variation, on repeated derivation of such measure from the sample, that is less than approximately 3 percent.
In further embodiments, the panel includes at least three constituents and optionally fewer than approximately 500 constituents.
In another embodiment, the biological condition being evaluated is with respect to a localized tissue of the subject and the sample is derived from tissue or fluid of a type distinct from that of the localized tissue.
In related embodiments, the biological condition may be any of the conditions identified in Tables 1 through 12 herein, in which case there are measurements conducted corresponding to constituents of the corresponding Gene Expression Panel. The panel in each case includes at least two, and optionally at least three, four, five, six, seven, eight, nine or ten, of the constituents of the corresponding Gene Expression Panel.
In another embodiment, there is provided a method of providing an index that is indicative of the inflammatory state of a subject based on a sample from the subject that includes: deriving from the sample a first profile data set, the first profile data set including a plurality of members, each member being a quantitative measure of the amount of a distinct RNA or protein constituent in a panel of constituents, the panel including at least two of the constituents of the Inflammation Gene Expression Panel of Table 1; (although in other embodiments, at least three, four, five, six or ten constituents of the panel of Table 1 may be used in a panel) wherein, in deriving the first profile data set, such measure is performed for each constituent both under conditions wherein specificity and efficiencies of amplification for all constituents are substantially similar and under substantially repeatable conditions; and applying values from the first profile data set to an index function that provides a mapping from an instance of a profile data set into a single-valued measure of biological condition (in an embodiment, this may be an inflammatory condition), so as to produce an index pertinent to the biological condition of the sample or the subject. The biological condition may be any condition that is assessable using an appropriate Gene Expression Panel; the measurement of the extent of inflammation using the Inflammation Gene Expression Panel is merely an example.
In additional embodiments, the mapping by the index function may be further based on an instance of a relevant baseline profile data set and values may be applied from a corresponding baseline profile data set from the same subject or from a population of subjects or samples with a similar or different biological condition. Additionally, the index function may be constructed to deviate from a normative value generally upwardly in an instance of an increase in expression of a constituent whose increase is associated with an increase of inflammation and also in an instance of a decrease in expression of a constituent whose decrease is associated with an increase of inflammation. The index function alternatively be constructed to weigh the expression value of a constituent in the panel generally in accordance with the extent to which its expression level is determined to be correlated with extent of inflammation. The index function may be alternatively constructed to take into account clinical insight into inflammation biology or to take into account experimentally derived data or to take into account relationships derived from computer analysis of profile data sets in a data base associating profile data sets with clinical and demographic data. In this connection, the construction of the index function may be achieved using statistical methods, which evaluate such data, to establish a model of constituent expression values that is an optimized predictor of extent of inflammation.
In another embodiment, the panel includes at least one constituent that is associated with a specific inflammatory disease.
The methods described above may further utilize the step wherein (i) the mapping by the index function is also based on an instance of at least one of demographic data and clinical data and (ii) values are applied from the first profile data set including applying a set of values associated with at least one of demographic data and clinical data.
In another embodiment of the above methods, a portion of deriving the first profile data set is performed at a first location and applying the values from the first profile data set is performed at a second location, and data associated with performing the portion of deriving the first profile data set are communicated to the second location over a network to enable, at the second location, applying the values from the first profile data set.
In an embodiment of the methods, the index function is a linear sum of terms, each term being a contribution function of a member of the profile data set. Moreover, the contribution function may be a weighted sum of powers of one of the member or its reciprocal, and the powers may be integral, so that the contribution function is a polynomial of one of the member or its reciprocal. Optionally, the polynomial is a linear polynomial. The profile data set may include at least three, four or all members corresponding to constituents selected from the group consisting of IL1A, IL1B, TNF, IFNG and IL10. The index function may be proportional to ¼{IL1A}+¼{IL1B}+¼{TNF}+¼{INFG}−1{IL10} and braces around a constituent designate measurement of such constituent.
In an additional embodiment, a method is provided of analyzing complex data associated with a sample from a subject for information pertinent to inflammation, the method that includes: deriving a Gene Expression Profile for the sample, the Gene Expression Profile being based on a Signature Panel for Inflammation; and using the Gene Expression Profile to determine a Gene Expression Profile Inflammatory Index for the sample.
In an additional embodiment, a method is provided of monitoring the biological condition of a subject, that includes deriving a Gene Expression Profile for each of a series of samples over time from the subject, the Gene Expression Profile being based on a Signature Panel for Inflammation; and for each of the series of samples, using the corresponding Gene Expression Profile to determine a Gene Expression Profile Inflammatory Index.
In an additional embodiment, there is provided a method of determining at least one of (i) an effective dose of an agent to be administered to a subject and (ii) a schedule for administration of an agent to a subject, the method including: deriving a Gene Expression Profile for a sample from the subject, the Gene Expression Profile being based on a Signature Panel for Inflammation; using the Gene Expression Profile to determine a Gene Expression Profile Inflammatory Index for the sample; and
using the Gene Expression Profile Inflammatory Index as an indicator in establishing at least one of the effective dose and the schedule.
In an additional embodiment, a method of guiding a decision to continue or modify therapy for a biological condition of a subject, is provided that includes: deriving a Gene Expression Profile for a sample from the subject, the Gene Expression Profile being based on a Signature Panel for Inflammation; and using the Gene Expression Profile to determine a Gene Expression Profile Inflammatory Index for the sample.
A method of predicting change in biological condition of a subject as a result of exposure to an agent, is provided that includes: deriving a first Gene Expression Profile for a first sample from the subject in the absence of the agent, the first Gene Expression Profile being based on a Signature Panel for Inflammation; deriving a second Gene Expression Profile for a second sample from the subject in the presence of the agent, the second Gene Expression Profile being based on the same Signature Panel; and using the first and second Gene Expression Profiles to determine correspondingly a first Gene Expression Profile Inflammatory Index and a second Gene Expression Profile Inflammatory Index. Accordingly, the agent may be a compound and the compound may be therapeutic.
In an additional embodiment, a method of evaluating a property of an agent is provided where the property is at least one of purity, potency, quality, efficacy or safety, the method including: deriving a first Gene Expression Profile from a sample reflecting exposure to the agent of (i) the sample, or (ii) a population of cells from which the sample is derived, or (iii) a subject from which the sample is derived; using the Gene Expression Profile to determine a Gene Expression Profile Inflammatory Index; and using the Gene Expression Profile Inflammatory Index in determining the property.
In accordance with another embodiment there is provided a method of providing an index that is indicative of the biological state of a subject based on a sample from the subject. The method of this embodiment includes:
deriving from the sample a first profile data set, the first profile data set including a plurality of members, each member being a quantitative measure of the amount of a distinct RNA or protein constituent in a panel of constituents, the panel including at least two of the constituents of the Inflammation Gene Expression Panel of Table 1; and
applying values from the first profile data set to an index function that provides a mapping from an instance of a profile data set into a single-valued measure of biological condition, so as to produce an index pertinent to the biological condition of the sample or the subject.
In carrying out this method the index function also uses data from a baseline profile data set for the panel. Each member of the baseline data set is a normative measure, determined with respect to a relevant population of subjects, of the amount of one of the constituents in the panel. In addition, in deriving the first profile data set and the baseline data set, such measure is performed for each constituent both under conditions wherein specificity and efficiencies of amplification for all constituents are substantially similar and under substantially repeatable conditions.
In another type of embodiment, there is provided a method, for evaluating a biological condition of a subject, based on a sample from the subject. In this embodiment, the method includes:
deriving from the sample a first profile data set, the first profile dataset including a plurality of members, each member being a quantitative measure of the amount of a distinct RNA or protein constituent in a panel of constituents selected so that measurement of the constituents enables measurement of the biological condition; and
producing a calibrated profile data set for the panel, wherein each member of the calibrated profile data set is a function of a corresponding member of the first profile data set and a corresponding member of a baseline profile data set for the panel.
In this embodiment, each member of the baseline data set is a normative measure, determined with respect to a relevant population of subjects, of the amount of one of the constituents in the panel, and the calibrated profile data set provides a measure of the biological condition of the subject.
In a similar type of embodiment, there is provided a method, for evaluating a biological condition of a subject, based on a sample from the subject, and the method of this embodiment includes:
applying the first sample or a portion thereof to a defined population of indicator cells;
obtaining from the indicator cells a second sample containing at least one of RNAs or proteins;
deriving from the second sample a first profile data set, the first profile data set including a plurality of members, each member being a quantitative measure of the amount of a distinct RNA or protein constituent in a panel of constituents selected so that measurement of the constituents enables measurement of the biological condition; and
producing a calibrated profile data set for the panel, wherein each member of the calibrated profile data set is a function of a corresponding member of the first profile data set and a corresponding member of a baseline profile data set for the panel, wherein each member of the baseline data set is a normative measure, determined with respect to a relevant population of subjects, of the amount of one of the constituents in the panel, the calibrated profile data set providing a measure of the biological condition of the subject.
Furthermore, another and similar, type of embodiment provides a method, for evaluating a biological condition affected by an agent. The method of this embodiment includes:
obtaining, from a target population of cells to which the agent has been administered, a sample having at least one of RNAs and proteins;
deriving from the sample a first profile data set, the first profile data set including a plurality of members, each member being a quantitative measure of the amount of a distinct RNA or protein constituent in a panel of constituents selected so that measurement of the constituents enables measurement of the biological condition; and
producing a calibrated profile data set for the panel, wherein each member of the calibrated profile data set is a function of a corresponding member of the first profile data set and a corresponding member of a baseline profile data set for the panel, wherein each member of the baseline data set is a normative measure, determined with respect to a relevant population of subjects, of the amount of one of the constituents in the panel, the calibrated profile data set providing a measure of the biological condition as affected by the agent.
In further embodiments based on these last three embodiments, the relevant population may be a population of healthy subjects. Alternatively, or in addition, the relevant population is has in common a property that is at least one of age group, gender, ethnicity, geographic location, diet, medical disorder, clinical indicator, medication, physical activity, body mass, and environmental exposure.
Alternatively or in addition, the panel includes at least two of the constituents of the Inflammation Gene Expression Panel of Table 1. (Other embodiments employ at least three, four, five, six, or ten of such constituents.) Also alternatively or in addition, in deriving the first profile data set, such measure is performed for each constituent both under conditions wherein specificity and efficiencies of amplification for all constituents are substantially similar and under substantially repeatable conditions. Also alternatively, when such measure is performed for each constituent both under conditions wherein specificity and efficiencies of amplification for all constituents are substantially similar and under substantially repeatable conditions, optionally one need not produce a calibrated profile data set, but may instead work directly with the first data set.
In another embodiment, there is provided a method, for evaluating the effect on a biological condition by a first agent in relation to the effect by a second agent. The method of this embodiment includes:
obtaining, from first and second target populations of cells to which the first and second agents have been respectively administered, first and second samples respectively, each sample having at least one of RNAs and proteins;
deriving from the first sample a first profile data set and from the second sample a second profile data set, the profile data sets each including a plurality of members, each member being a quantitative measure of the amount of a distinct RNA or protein constituent in a panel of constituents selected so that measurement of the constituents enables measurement of the biological condition; and
producing for the panel a first calibrated profile data set and a second profile data set, wherein (i) each member of the first calibrated profile data set is a function of a corresponding member of the first profile data set and a corresponding member of a baseline profile data set for the panel, wherein each member of the baseline data set is a normative measure, determined with respect to a relevant population of subjects, of the amount of one of the constituents in the panel, and (ii) each member of the second calibrated profile data set is a function of a corresponding member of the second profile data set and a corresponding member of the baseline profile data set, the calibrated profile data sets providing a measure of the effect by the first agent on the biological condition in relation to the effect by the second agent.
In this embodiment, in deriving the first and second profile data sets, such measure is performed for each constituent both under conditions wherein specificity and efficiencies of amplification for all constituents are substantially similar and under substantially repeatable conditions. In a further related embodiment, the first agent is a first drug and the second agent is a second drug. In another related embodiment, the first agent is a drug and the second agent is a complex mixture. In yet another related embodiment, the first agent is a drug and the second agent is a nutriceutical.
The foregoing features of the invention will be more readily understood by reference to the following detailed description, taken with reference to the accompanying drawings, in which:
1B illustrates use of an inflammation index in relation to the data of
Each of
Definitions
The following terms shall have the meanings indicated unless the context otherwise requires:
“Algorithm” is a set of rules for describing a biological condition. The rule set may be defined exclusively algebraically but may also include alternative or multiple decision points requiring domain-specific knowledge, expert interpretation or other clinical indicators.
An “agent” is a“composition” or a “stimulus”, as those terms are defined herein, or a combination of a composition and a stimulus.
“Amplification” in the context of a quantitative RT-PCR assay is a function of the number of DNA replications that are tracked to provide a quantitative determination of its concentration. “Amplification” here refers to a degree of sensitivity and specificity of a quantitative assay technique. Accordingly, amplification provides a measurement of concentrations of constituents that is evaluated under conditions wherein the efficiency of amplification and therefore the degree of sensitivity and reproducibility for measuring all constituents is substantially similar.
A “baseline profile data set” is a set of values associated with constituents of a Gene Expression Panel resulting from evaluation of a biological sample (or population of samples) under a desired biological condition that is used for mathematically normative purposes. The desired biological condition may be, for example, the condition of a subject (or population of subjects) before exposure to an agent or in the presence of an untreated disease or in the absence of a disease. Alternatively, or in addition, the desired biological condition may be health of a subject or a population of subjects. Alternatively, or in addition, the desired biological condition may be that associated with a population subjects selected on the basis of at least one of age group, gender, ethnicity, geographic location, diet, medical disorder, clinical indicator, medication, physical activity, body mass, and environmental exposure.
A “biological condition” of a subject is the condition of the subject in a pertinent realm that is under observation, and such realm may include any aspect of the subject capable of being monitored for change in condition, such as health, disease including cancer; trauma; aging; infection; tissue degeneration; developmental steps; physical fitness; obesity, and mood. As can be seen, a condition in this context may be chronic or acute or simply transient. Moreover, a targeted biological condition may be manifest throughout the organism or population of cells or may be restricted to a specific organ (such as skin, heart, eye or blood), but in either case, the condition may be monitored directly by a sample of the affected population of cells or indirectly by a sample derived elsewhere from the subject. The term “biological condition” includes a “physiological condition”.
“Body fluid” of a subject includes blood, urine, spinal fluid, lymph, mucosal secretions, prostatic fluid, semen, haemolymph or any other body fluid known in the art for a subject.
“Calibrated profile data set” is a function of a member of a first profile data set and a corresponding member of a baseline profile data set for a given constituent in a panel.
A “clinical indicator” is any physiological datum used alone or in conjunction with other data in evaluating the physiological condition of a collection of cells or of an organism. This term includes pre-clinical indicators.
A “composition” includes a chemical compound, a nutriceutical, a pharmaceutical, a homeopathic formulation, an allopathic formulation, a naturopathic formulation, a combination of compounds, a toxin, a food, a food supplement, a mineral, and a complex mixture of substances, in any physical state or in a combination of physical states.
To “derive” a profile data set from a sample includes determining a set of values associated with constituents of a Gene Expression Panel either (i) by direct measurement of such constituents in a biological sample or (ii) by measurement of such constituents in a second biological sample that has been exposed to the original sample or to matter derived from the original sample.
“Distinct RNA or protein constituent” in a panel of constituents is a distinct expressed product of a gene, whether RNA or protein. An “expression” product of a gene includes the gene product whether RNA or protein resulting from translation of the messenger RNA.
A “Gene Expression Panel” is an experimentally verified set of constituents, each constituent being a distinct expressed product of a gene, whether RNA or protein, wherein constituents of the set are selected so that their measurement provides a measurement of a targeted biological condition.
A “Gene Expression Profile” is a set of values associated with constituents of a Gene Expression Panel resulting from evaluation of a biological sample (or population of samples).
A “Gene Expression Profile Inflammatory Index” is the value of an index function that provides a mapping from an instance of a Gene Expression Profile into a single-valued measure of inflammatory condition.
The “health” of a subject includes mental, emotional, physical, spiritual, allopathic, naturopathic and homeopathic condition of the subject.
“Index” is an arithmetically or mathematically derived numerical characteristic developed for aid in simplifying or disclosing or informing the analysis of more complex quantitative information. A disease or population index may be determined by the application of a specific algorithm to a plurality of subjects or samples with a common biological condition.
“Inflammation” is used herein in the general medical sense of the word and may be an acute or chronic; simple or supporative; localized or disseminated; cellular and tissue response, initiated or sustained by any number of chemical, physical or biological agents or combination of agents.
“Inflammatory state” is used to indicate the relative biological condition of a subject resulting from inflammation, or characterizing the degree of inflammation
A “large number” of data sets based on a common panel of genes is a number of data sets sufficiently large to permit a statistically significant conclusion to be drawn with respect to an instance of a data set based on the same panel.
A “normative” condition of a subject to whom a composition is to be administered means the condition of a subject before administration, even if the subject happens to be suffering from a disease.
A “panel” of genes is a set of genes including at least two constituents.
A “sample” from a subject may include a single cell or multiple cells or fragments of cells or an aliquot of body fluid, taken from the subject, by means including venipuncture, excretion, ejaculation, massage, biopsy, needle aspirate, lavage sample, scraping, surgical incision or intervention or other means known in the art.
A “Signature Profile” is an experimentally verified subset of a Gene Expression Profile selected to discriminate a biological condition, agent or physiological mechanism of action.
A “Signature Panel” is a subset of a Gene Expression Panel, the constituents of which are selected to permit discrimination of a biological condition, agent or physiological mechanism of action.
A “subject” is a cell, tissue, or organism, human or non-human, whether in vivo, ex vivo or in vitro, under observation. When we refer to evaluating the biological condition of a subject based on a sample from the subject, we include using blood or other tissue sample from a human subject to evaluate the human subject's condition; but we also include, for example, using a blood sample itself as the subject to evaluate, for example, the effect of therapy or an agent upon the sample.
A “stimulus” includes (i) a monitored physical interaction with a subject, for example ultraviolet A or B, or light therapy for seasonal affective disorder, or treatment of psoriasis with psoralen or treatment of melanoma with embedded radioactive seeds, other radiation exposure, and (ii) any monitored physical, mental, emotional, or spiritual activity or inactivity of a subject.
“Therapy” includes all interventions whether biological, chemical, physical, metaphysical, or combination of the foregoing, intended to sustain or alter the monitored biological condition of a subject.
The PCT patent application publication number WO 01/25473, published Apr. 12, 2001, entitled “Systems and Methods for Characterizing a Biological Condition or Agent Using Calibrated Gene Expression Profiles,” filed for an invention by inventors herein, and which is herein incorporated by reference, discloses the use of Gene Expression Panels for the evaluation of (i) biological condition (including with respect to health and disease) and (ii) the effect of one or more agents on biological condition (including with respect to health, toxicity, therapeutic treatment and drug interaction).
In particular, Gene Expression Panels may be used for measurement of therapeutic efficacy of natural or synthetic compositions or stimuli that may be formulated individually or in combinations or mixtures for a range of targeted physiological conditions; prediction of toxicological effects and dose effectiveness of a composition or mixture of compositions for an individual or in a population; determination of how two or more different agents administered in a single treatment might interact so as to detect any of synergistic, additive, negative, neutral or toxic activity; performing pre-clinical and clinical trials by providing new criteria for pre-selecting subjects according to informative profile data sets for revealing disease status; and conducting preliminary dosage studies for these patients prior to conducting phase 1 or 2 trials. These Gene Expression Panels may be employed with respect to samples derived from subjects in order to evaluate their biological condition.
A Gene Expression Panel is selected in a manner so that quantitative measurement of RNA or protein constituents in the Panel constitutes a measurement of a biological condition of a subject. In one kind of arrangement, a calibrated profile data set is employed. Each member of the calibrated profile data set is a function of (i) a measure of a distinct constituent of a Gene Expression Panel and (ii) a baseline quantity.
We have found that valuable and unexpected results may be achieved when the quantitative measurement of constituents is performed under repeatable conditions (within a degree of repeatability of measurement of better than twenty percent, and preferably five percent or better, and more preferably three percent or better). For the purposes of this description and the following claims, we regard a degree of repeatability of measurement of better than twenty percent as providing measurement conditions that are “substantially repeatable”. In particular, it is desirable that, each time a measurement is obtained corresponding to the level of expression of a constituent in a particular sample, substantially the same measurement should result for the substantially the same level of expression. In this manner, expression levels for a constituent in a Gene Expression Panel may be meaningfully compared from sample to sample. Even if the expression level measurements for a particular constituent are inaccurate (for example, say, 30% too low), the criterion of repeatability means that all measurements for this constituent, if skewed, will nevertheless be skewed systematically, and therefore measurements of expression level of the constituent may be compared meaningfully. In this fashion valuable information may be obtained and compared concerning expression of the constituent under varied circumstances.
In addition to the criterion of repeatability, it is desirable that a second criterion also be satisfied, namely that quantitative measurement of constituents is performed under conditions wherein efficiencies of amplification for all constituents are substantially similar (within one to two percent and typically one percent or less). When both of these criteria are satisfied, then measurement of the expression level of one constituent may be meaningfully compared with measurement of the expression level of another constituent in a given sample and from sample to sample.
Present embodiments relate to the use of an index or algorithm resulting from quantitative measurement of constituents, and optionally in addition, derived from either expert analysis or computational biology (a) in the analysis of complex data sets; (b) to control or normalize the influence of uninformative or otherwise minor variances in gene expression values between samples or subjects; (c) to simplify the characterization of a complex data set for comparison to other complex data sets, databases or indices or algorithms derived from complex data sets; (d) to monitor a biological condition of a subject; (e) for measurement of therapeutic efficacy of natural or synthetic compositions or stimuli that may be formulated individually or in combinations or mixtures for a range of targeted physiological conditions; (f) for predictions of toxicological effects and dose effectiveness of a composition or mixture of compositions for an individual or in a population; (g) for determination of how two or more different agents administered in a single treatment might interact so as to detect any of synergistic, additive, negative, neutral of toxic activity (h) for performing pre-clinical and clinical trials by providing new criteria for pre-selecting subjects according to informative profile data sets for revealing disease status and conducting preliminary dosage studies for these patients prior to conducting phase 1 or 2 trials.
Gene expression profiling and the use of index characterization for a particular condition or agent or both may be used to reduce the cost of phase 3 clinical trials and may be used beyond phase 3 trials; labeling for approved drugs; selection of suitable medication in a class of medications for a particular patient that is directed to their unique physiology; diagnosing or determining a prognosis of a medical condition or an infection which may precede onset of symptoms or alternatively diagnosing adverse side effects associated with administration of a therapeutic agent; managing the health care of a patient; and quality control for different batches of an agent or a mixture of agents.
The methods disclosed here may be applied to cells of humans, mammals or other organisms without the need for undue experimentation by one of ordinary skill in the art because all cells transcribe RNA and it is known in the art how to extract RNA from all types of cells.
The general approach to selecting constituents of a Gene Expression Panel has been described in PCT application publication number WO 01/ 25473. We have designed and experimentally verified a wide range of Gene Expression Panels, each panel providing a quantitative measure, of biological condition, that is derived from a sample of blood or other tissue. For each panel, experiments have verified that a Gene Expression Profile using the panel's constituents is informative of a biological condition. (We show elsewhere that in being informative of biological condition, the Gene Expression Profile can be used to used, among other things, to measure the effectiveness of therapy, as well as to provide a target for therapeutic intervention.) Examples of Gene Expression Panels, along with a brief description of each panel constituent, are provided in tables attached hereto as follows:
Table 1. Inflammation Gene Expression Panel
Table 2. Diabetes Gene Expression Panel
Table 3. Prostate Gene Expression Panel
Table 4. Skin Response Gene Expression Panel
Table 5. Liver Metabolism and Disease Gene Expression Panel
Table 6. Endothelial Gene Expression Panel
Table 7. Cell Health and Apoptosis Gene Expression Panel
Table 8. Cytokine Gene Expression Panel
Table 9. TNF/IL1 Inhibition Gene Expression Panel
Table 10. Chemokine Gene Expression Panel
Table 11. Breast Cancer Gene Expression Panel
Table 12. Infectious Disease Gene Expression Panel
Other panels may be constructed and experimentally verified by one of ordinary skill in the art in accordance with the principles articulated in the present application.
We commonly run a sample through a panel in quadruplicate; that is, a sample is divided into aliquots and for each aliquot we measure concentrations of each constituent in a Gene Expression Panel. Over a total of 900 constituent assays, with each assay conducted in quadruplicate, we found an average coefficient of variation, (standard deviation/average)*100, of less than 2 percent, typically less than 1 percent, among results for each assay. This figure is a measure of what we call “intra-assay variability”. We have also conducted assays on different occasions using the same sample material. With 72 assays, resulting from concentration measurements of constituents in a panel of 24 members, and such concentration measurements determined on three different occasions over time, we found an average coefficient of variation of less than 5 percent, typically less than 2 percent. We regard this as a measure of what we call “inter-assay variability”.
We have found it valuable in using the quadruplicate test results to identify and eliminate data points that are statistical “outliers”; such data points are those that differ by a percentage greater, for example, than 3% of the average of all four values and that do not result from any systematic skew that is greater, for example, than 1%. Moreover, if more than one data point in a set of four is excluded by this procedure, then all data for the relevant constituent is discarded.
For measuring the amount of a particular RNA in a sample, we have used methods known to one of ordinary skill in the art to extract and quantify transcribed RNA from a sample with respect to a constituent of a Gene Expression Panel. (See detailed protocols below. Also see PCT application publication number WO 98/24935 herein incorporated by reference for RNA analysis protocols). Briefly, RNA is extracted from a sample such as a tissue, body fluid, or culture medium in which a population of a subject might be growing. For example, cells may be lysed and RNA eluted in a suitable solution in which to conduct a DNAse reaction. First strand synthesis may be performed using a reverse transcriptase. Gene amplification, more specifically quantitative PCR assays, can then conducted and the gene of interest size calibrated against a marker such as 18S rRNA (Hirayama et al., Blood 92, 1998: 46-52). Samples are measured in multiple duplicates, for example, 4 replicates. Relative quantitation of the mRNA is determined by the difference in threshhold cycles between the internal control and the gene of interest In an embodiment of the invention, quantitative PCR is performed using amplification, reporting agents and instruments such as those supplied commercially by Applied Biosystems (Foster City, Calif.). Given a defined efficiency of amplification of target transcripts, the point (e.g., cycle number) that signal from amplified target template is detectable may be directly related to the amount of specific message transcript in the measured sample. Similarly, other quantifiable signals such as fluorescence, enzyme activity, disintegrations per minute, absorbance, etc., when correlated to a known concentration of target templates (e.g., a reference standard curve) or normalized to a standard with limited variability can be used to quantify the number of target templates in an unknown sample.
Although not limited to amplification methods, quantitative gene expression techniques may utilize amplification of the target transcript. Alternatively or in combination with amplification of the target transcript, amplification of the reporter signal may also be used. Amplification of the target template may be accomplished by isothermic gene amplification strategies, or by gene amplification by thermal cycling such as PCR.
It is desirable to obtain a definable and reproducible correlation between the amplified target or reporter and the concentration of starting templates. We have discovered that this objective can be achieved by careful attention to, for example, consistent primer-template ratios and a strict adherence to a narrow permissible level of experimental amplification efficiencies (for example 99.0 to 100% relative efficiency, typically 99.8 to 100% relative efficiency). For example, in determining gene expression levels with regard to a single Gene Expression Profile, it is necessary that all constituents of the panels maintain a similar and limited range of primer template ratios (for example, within a 10-fold range) and amplification efficiencies (within, for example, less than 1%) to permit accurate and precise relative measurements for each constituent. We regard amplification efficiencies as being “substantially similar”, for the purposes of this description and the following claims, if they differ by no more than approximately 10%. Preferably they should differ by less than approximately 2% and more preferably by less than approximately 1%. These constraints should be observed over the entire range of concentration levels to be measured associated with the relevant biological condition. While it is thus necessary for various embodiments herein to satisfy criteria that measurements are achieved under measurement conditions that are substantially repeatable and wherein specificity and efficiencies of amplification for all constituents are substantially similar, nevertheless, it is within the scope of the present invention as claimed herein to achieve such measurement conditions by adjusting assay results that do not satisfy these criteria directly, in such a manner as to compensate for errors, so that the criteria are satisfied after suitable adjustment of assay results.
In practice, we run tests to assure that these conditions are satisfied. For example, we typically design and manufacture a number of primer-probe sets, and determine experimentally which set gives the best performance. Even though primer-probe design and manufacture can be enhanced using computer techniques known in the art, and notwithstanding common practice, we still find that experimental validation is useful. Moreover, in the course of experimental validation, we associate with the selected primer-probe combination a set of features:
The reverse primer should be complementary to the coding DNA strand. In one embodiment, the primer should be located across an intron-exon junction, with not more than three bases of the three-prime end of the reverse primer complementary to the proximal exon. (If more than three bases are complementary, then it would tend to competitively amplify genomic DNA.)
In an embodiment of the invention, the primer probe should amplify cDNA of less than 110 bases in length and should not amplify genomic DNA or transcripts or cDNA from related but biologically irrelevant loci.
A suitable target of the selected primer probe is first strand cDNA, which may be prepared, in one embodiment, is described as follows:
(a) Use of whole blood for ex vivo assessment of a biological condition affected by an agent.
Human blood is obtained by venipuncture and prepared for assay by separating samples for baseline, no stimulus, and stimulus with sufficient volume for at least three time points. Typical stimuli include lipopolysaccharide (LPS), phytohemagglutinin (PHA) and heat-killed staphylococci (HKS) or carrageean and may be used individually (typically) or in combination. The aliquots of heparinized, whole blood are mixed without stimulus and held at 37° C. in an atmosphere of 5% CO2 for 30 minutes. Stimulus is added at varying concentrations, mixed and held loosely capped at 37° C. for 30 min. Additional test compounds may be added at this point and held for varying times depending on the expected pharmacokinetics of the test compound. At defined times, cells are collected by centrifugation, the plasma removed and RNA extracted by various standard means.
Nucleic acids, RNA and or DNA are purified from cells, tissues or fluids of the test population or indicator cell lines. RNA is preferentially obtained from the nucleic acid mix using a variety of standard procedures (or RNA Isolation Strategies, pp. 55-104, in RNA Methodologies, A laboratory guide for isolation and characterization, 2nd edition, 1998, Robert E. Farrell, Jr., Ed., Academic Press), in the present using a filter-based RNA isolation system from Ambion (RNAqueous™, Phenol-free Total RNA Isolation Kit, Catalog #1912, version 9908; Austin, Tex.).
In accordance with one procedure, the whole blood assay for Gene Expression Profiles determination was carried out as follows: Human whole blood was drawn into 10 mL Vacutainer tubes with Sodium Heparin. Blood samples were mixed by gently inverting tubes 4-5 times. The blood was used within 10-15 minutes of draw. In the experiments, blood was diluted 2-fold, i.e. per sample per time point, 0.6 mL whole blood+0.6 mL stimulus. The assay medium was prepared and the stimulus added as appropriate.
A quantity (0.6 mL) of whole blood was then added into each 12×75 mm polypropylene tube. 0.6 mL of 2× LPS (from E. coli serotye 0127:B8, Sigma #L3880 or serotype 055, Sigma #L4005, 10 ng/ml, subject to change in different lots) into LPS tubes was added. Next, 0.6 mL assay medium was added to the “control” tubes with duplicate tubes for each condition. The caps were closed tightly. The tubes were inverted 2-3 times to mix samples. Caps were loosened to first stop and the tubes incubated@37° C., 5% CO2 for 6 hours. At 6 hours, samples were gently mixed to resuspend blood cells, and 1 mL was removed from each tube (using a micropipettor with barrier tip), and transferred to a 2 mL “dolphin” microfuge tube (Costar #3213).
The samples were then centrifuged for 5 min at 500×g, ambient temperature (IEC centrifuge or equivalent, in microfuge tube adapters in swinging bucket), and as much serum from each tube was removed as possible and discarded. Cell pellets were placed on ice; and RNA extracted as soon as possible using an Ambion RNAqueous kit.
(b) Amplification Strategies.
Specific RNAs are amplified using message specific primers or random primers. The specific primers are synthesized from data obtained from public databases (e.g., Unigene, National Center for Biotechnology Information, National Library of Medicine, Bethesda, Md.), including information from genomic and cDNA libraries obtained from humans and other animals. Primers are chosen to preferentially amplify from specific RNAs obtained from the test or indicator samples, see, for example, RT PCR, Chapter 15 in RNA Methodologies, A laboratory guide for isolation and characterization, 2nd edition, 1998, Robert E. Farrell, Jr., Ed., Academic Press; or Chapter 22 pp. 143-151, RNA isolation and characterization protocols, Methods in molecular biology, Volume 86, 1998, R. Rapley and D. L. Manning Eds., Human Press, or 14 in Statistical refinement of primer design parameters, Chapter 5, pp. 55-72, PCR applications: protocols for functional genomics, M. A. Innis, D. H. Gelfand and J. J. Sninsky, Eds., 1999, Academic Press). Amplifications are carried out in either isothermic conditions or using a thermal cycler (for example, a ABI 9600 or 9700 or 7700 obtained from Applied Biosystems, Foster City, Calif.; see Nucleic acid detection methods, pp. 1-24, in Molecular methods for virus detection, D. L. Wiedbrauk and D. H., Farkas, Eds., 1995, Academic Press). Amplified nucleic acids are detected using fluorescent-tagged detection primers (see, for example, Taqman™ PCR Reagent Kit, Protocol, part number 402823 revision A, 1996, Applied Biosystems, Foster City Calif.) that are identified and synthesized from publicly known databases as described for the amplification primers. In the present case, amplified DNA is detected and quantified using the ABI Prism 7700 Sequence Detection System obtained from Applied Biosystems (Foster City, Calif.). Amounts of specific RNAs contained in the test sample or obtained from the indicator cell lines can be related to the relative quantity of fluorescence observed (see for example, Advances in quantitative PCR technology: 5′ nuclease assays, Y. S. Lie and C. J. Petropolus, Current Opinion in Biotechnology, 1998, 9:43-48, or Rapid thermal cycling and PCR kinetics, pp. 211-229, chapter 14 in PCR applications: protocols for functional genomics, M. A. Innis, D. H. Gelfand and J. J. Sninsky, Eds., 1999, Academic Press).
As a particular implementation of the approach described here, we describe in detail a procedure for synthesis of first strand cDNA for use in PCR. This procedure can be used for both whole blood RNA and RNA extracted from cultured cells (i.e. THP-1 cells).
1. Applied Biosystems TAQMAN Reverse Transcription Reagents Kit (P/N 808-0234). Kit Components: 10× TaqMan RT Buffer, 25 mM Magnesium chloride, deoxyNTPs mixture, Random Hexamers, RNase Inhibitor, MultiScribe Reverse Transcriptase (50 U/mL) (2) RNase/DNase free water (DEPC Treated Water from Ambion (P/N 9915G), or equivalent)
1. Place RNase Inhibitor and MultiScribe Reverse Transcriptase on ice immediately. All other reagents can be thawed at room temperature and then placed on ice.
2. Remove RNA samples from −80° C. freezer and thaw at room temperature and then place immediately on ice.
3. Prepare the following cocktail of Reverse Transcriptase Reagents for each 100 mL RT reaction (for multiple samples, prepare extra cocktail to allow for pipetting error):
4. Bring each RNA sample to a total volume of 20 mL in a 1.5 mL microcentrifuge tube (for example, for THP-1 RNA, remove 10 mL RNA and dilute to 20 mL with RNase/DNase free water, for whole blood RNA use 20 mL total RNA) and add 80 mL RT reaction mix from step 5,2,3. Mix by pipetting up and down.
5. Incubate sample at room temperature for 10 minutes.
6. Incubate sample at 37° C. for 1 hour.
7. Incubate sample at 90° C. for 10 minutes.
8. Quick spin samples in microcentrifuge.
9. Place sample on ice if doing PCR immediately, otherwise store sample at −20° C. for future use.
10. PCR QC should be run on all RT samples using 18S and b-actin (see SOP 200-020).
The use of the primer probe with the first strand cDNA as described above to permit measurement of constituents of a Gene Expression Panel is as follows:
Set up of a 24-gene Human Gene Expression Panel for Inflammation.
1. 20× Primer/Probe Mix for each gene of interest.
2. 20× Primer/Probe Mix for 18S endogenous control.
3. 2× Taqman Universal PCR Master Mix.
4. cDNA transcribed from RNA extracted from cells.
5. Applied Biosystems 96-Well Optical Reaction Plates.
6. Applied Biosystems Optical Caps, or optical-clear film.
7. Applied Biosystem Prism 7700 Sequence Detector.
1. Make stocks of each Primer/Probe mix containing the Primer/Probe for the gene of interest, Primer/Probe for 18S endogenous control, and 2× PCR Master Mix as follows. Make sufficient excess to allow for pipetting error e.g. approximately 10% excess. The following example illustrates a typical set up for one gene with quadruplicate samples testing two conditions (2 plates).
2. Make stocks of cDNA targets by diluting 95 μl of cDNA into 2000 μl of water. The amount of cDNA is adjusted to give Ct values between 10 and 18, typically between 12 and 13.
3. Pipette 15 μl of Primer/Probe mix into the appropriate wells of an Applied Biosystems 96-Well Optical Reaction Plate.
4. Pipette 10 μl of cDNA stock solution into each well of the Applied Biosystems 96-Well Optical Reaction Plate.
5. Seal the plate with Applied Biosystems Optical Caps, or optical-clear film.
6. Analyze the plate on the AB Prism 7700 Sequence Detector.
Methods herein may also be applied using proteins where sensitive quantitative techniques, such as an Enzyme Linked ImmunoSorbent Assay (ELISA) or mass spectroscopy, are available and well-known in the art for measuring the amount of a protein constituent. (see WO 98/24935 herein incorporated by reference).
The analyses of samples from single individuals and from large groups of individuals provide a library of profile data sets relating to a particular panel or series of panels. These profile data sets may be stored as records in a library for use as baseline profile data sets. As the term “baseline” suggests, the stored baseline profile data sets serve as comparators for providing a calibrated profile data set that is informative about a biological condition or agent. Baseline profile data sets may be stored in libraries and classified in a number of cross-referential ways. One form of classification may rely on the characteristics of the panels from which the data sets are derived. Another form of classification may be by particular biological condition. The concept of biological condition encompasses any state in which a cell or population of cells may be found at any one time. This state may reflect geography of samples, sex of subjects or any other discriminator. Some of the discriminators may overlap. The libraries may also be accessed for records associated with a single subject or particular clinical trial. The classification of baseline profile data sets may further be annotated with medical information about a particular subject, a medical condition, a particular agent etc.
The choice of a baseline profile data set for creating a calibrated profile data set is related to the biological condition to be evaluated, monitored, or predicted, as well as, the intended use of the calibrated panel, e.g., as to monitor drug development, quality control or other uses. It may be desirable to access baseline profile data sets from the same subject for whom a first profile data set is obtained or from different subject at varying times, exposures to stimuli, drugs or complex compounds; or may be derived from like or dissimilar populations.
The profile data set may arise from the same subject for which the first data set is obtained, where the sample is taken at a separate or similar time, a different or similar site or in a different or similar physiological condition. For example,
Selected baseline profile data sets may be also be used as a standard by which to judge manufacturing lots in terms of efficacy, toxicity, etc. Where the effect of a therapeutic agent is being measured, the baseline data set may correspond to Gene Expression Profiles taken before administration of the agent. Where quality control for a newly manufactured product is being determined, the baseline data set may correspond with a gold standard for that product. However, any suitable normalization techniques may be employed. For example, an average baseline profile data set is obtained from authentic material of a naturally grown herbal nutriceutical and compared over time and over different lots in order to demonstrate consistency, or lack of consistency, in lots of compounds prepared for release.
Given the repeatability we have achieved in measurement of gene expression, described above in connection with “Gene Expression Panels” and “gene amplification”, we conclude that where differences occur in measurement under such conditions, the differences are attributable to differences in biological condition. Thus we have found that calibrated profile data sets are highly reproducible in samples taken from the same individual under the same conditions. We have similarly found that calibrated profile data sets are reproducible in samples that are repeatedly tested. We have also found repeated instances wherein calibrated profile data sets obtained when samples from a subject are exposed ex vivo to a compound are comparable to calibrated profile data from a sample that has been exposed to a sample in vivo. We have also found, importantly, that an indicator cell line treated with an agent can in many cases provide calibrated profile data sets comparable to those obtained from in vivo or ex vivo populations of cells. Moreover, we have found that administering a sample from a subject onto indicator cells can provide informative calibrated profile data sets with respect to the biological condition of the subject including the health, disease states, therapeutic interventions, aging or exposure to environmental stimuli or toxins of the subject.
The calibrated profile data set may be expressed in a spreadsheet or represented graphically for example, in a bar chart or tabular form but may also be expressed in a three dimensional representation. The function relating the baseline and profile data may be a ratio expressed as a logarithm. The constituent may be itemized on the x-axis and the logarithmic scale may be on the y-axis. Members of a calibrated data set may be expressed as a positive value representing a relative enhancement of gene expression or as a negative value representing a relative reduction in gene expression with respect to the baseline.
Each member of the calibrated profile data set should be reproducible within a range with respect to similar samples taken from the subject under similar conditions. For example, the calibrated profile data sets may be reproducible within one order of magnitude with respect to similar samples taken from the subject under similar conditions. More particularly, the members may be reproducible within 50%, more particularly reproducible within 20%, and typically within 10%. In accordance with embodiments of the invention, a pattern of increasing, decreasing and no change in relative gene expression from each of a plurality of gene loci examined in the Gene Expression Panel may be used to prepare a calibrated profile set that is informative with regards to a biological condition, biological efficacy of an agent treatment conditions or for comparison to populations. Patterns of this nature may be used to identify likely candidates for a drug trial, used alone or in combination with other clinical indicators to be diagnostic or prognostic with respect to a biological condition or may be used to guide the development of a pharmaceutical or nutriceutical through manufacture, testing and marketing.
The numerical data obtained from quantitative gene expression and numerical data from calibrated gene expression relative to a baseline profile data set may be stored in databases or digital storage mediums and may retrieved for purposes including managing patient health care or for conducting clinical trials or for characterizing a drug. The data may be transferred in physical or wireless networks via the World Wide Web, email, or internet access site for example or by hard copy so as to be collected and pooled from distant geographic sites (
In an embodiment of the present invention, a descriptive record is stored in a single database or multiple databases where the stored data includes the raw gene expression data (first profile data set) prior to transformation by use of a baseline profile data set, as well as a record of the baseline profile data set used to generate the calibrated profile data set including for example, annotations regarding whether the baseline profile data set is derived from a particular Signature Panel and any other annotation that facilitates interpretation and use of the data.
Because the data is in a universal format, data handling may readily be done with a computer. The data is organized so as to provide an output optionally corresponding to a graphical representation of a calibrated data set.
For example, a distinct sample derived from a subject being at least one of RNA or protein may be denoted as PI. The first profile data set derived from sample PI is denoted Mj, where Mj is a quantitative measure of a distinct RNA or protein constituent of PI. The record Ri is a ratio of M and P and may be annotated with additional data on the subject relating to, for example, age, diet, ethnicity, gender, geographic location, medical disorder, mental disorder, medication, physical activity, body mass and environmental exposure. Moreover, data handling may further include accessing data from a second condition database which may contain additional medical data not presently held with the calibrated profile data sets. In this context, data access may be via a computer network.
The above described data storage on a computer may provide the information in a form that can be accessed by a user. Accordingly, the user may load the information onto a second access site including downloading the information. However, access may be restricted to users having a password or other security device so as to protect the medical records contained within. A feature of this embodiment of the invention is the ability of a user to add new or annotated records to the data set so the records become part of the biological information.
The graphical representation of calibrated profile data sets pertaining to a product such as a drug provides an opportunity for standardizing a product by means of the calibrated profile, more particularly a signature profile. The profile may be used as a feature with which to demonstrate relative efficacy, differences in mechanisms of actions, etc. compared to other drugs approved for similar or different uses.
The various embodiments of the invention may be also implemented as a computer program product for use with a computer system. The product may include program code for deriving a first profile data set and for producing calibrated profiles. Such implementation may include a series of computer instructions fixed either on a tangible medium, such as a computer readable medium (for example, a diskette, CD-ROM, ROM, or fixed disk), or transmittable to a computer system via a modem or other interface device, such as a communications adapter coupled to a network. The network coupling may be for example, over optical or wired communications lines or via wireless techniques (for example, microwave, infrared or other transmission techniques) or some combination of these. The series of computer instructions preferably embodies all or part of the functionality previously described herein with respect to the system. Those skilled in the art should appreciate that such computer instructions can be written in a number of programming languages for use with many computer architectures or operating systems. Furthermore, such instructions may be stored in any memory device, such as semiconductor, magnetic, optical or other memory devices, and may be transmitted using any communications technology, such as optical, infrared, microwave, or other transmission technologies. It is expected that such a computer program product may be distributed as a removable medium with accompanying printed or electronic documentation (for example, shrink wrapped software), preloaded with a computer system (for example, on system ROM or fixed disk), or distributed from a server or electronic bulletin board over a network (for example, the Internet or World Wide Web). In addition, a computer system is further provided including derivative modules for deriving a first data set and a calibration profile data set.
The calibration profile data sets in graphical or tabular form, the associated databases, and the calculated index or derived algorithm, together with information extracted from the panels, the databases, the data sets or the indices or algorithms are commodities that can be sold together or separately for a variety of purposes as described in WO 01/25473.
In combination, (i) the remarkable consistency of Gene Expression Profiles with respect to a biological condition across a population and (ii) the use of procedures that provide substantially reproducible measurement of constituents in a Gene Expression Panel giving rise to a Gene Expression Profile, under measurement conditions wherein specificity and efficiencies of amplification for all constituents of the panel are substantially similar, make possible the use of an index that characterizes a Gene Expression Profile, and which therefore provides a measurement of a biological condition.
An index may be constructed using an index function that maps values in a Gene Expression Profile into a single value that is pertinent to the biological condition at hand. The values in a Gene Expression Profile are the amounts of each constituent of the Gene Expression Panel that corresponds to the Gene Expression Profile. These constituent amounts form a profile data set, and the index function generates a single value—the index—from the members of the profile data set.
The index function may conveniently be constructed as a linear sum of terms, each term being what we call a “contribution function” of a member of the profile data set. For example, the contribution function may be a constant times a power of a member of the profile data set. So the index function would have the form
I=ΣC
i
M
i
P(i),
where I is the index, Mi is the value of the member i of the profile data set, Ci is a constant, and P(i) is a power to which Mi is raised, the sum being formed for all integral values of i up to the number of members in the data set. We thus have a linear polynomial expression.
The values Ci and P(i) may be determined in a number of ways, so that the index I is informative of the pertinent biological condition. One way is to apply statistical techniques, such as latent class modeling, to the profile data sets to correlate clinical data or experimentally derived data, or other data pertinent to the biological condition. In this connection, for example, may be employed the software from Statistical Innovations, Belmont, Mass., called Latent Gold®. See the web pages at www.statisticalinnovations.com/lg/, which are hereby incorporated herein by reference.
Alternatively, other simpler modeling techniques may be employed in a manner known in the art. The index function for inflammation may be constructed, for example, in a manner that a greater degree of inflammation (as determined by the a profile data set for the Inflammation Gene Expression Profile) correlates with a large value of the index function. In a simple embodiment, therefore, each P(i) may be +1 or −1, depending on whether the constituent increases or decreases with increasing inflammation. As discussed in further detail below, we have constructed a meaningful inflammation index that is proportional to the expression
¼{IL1A}+¼{IL1B}+¼{TNF}+¼{INFG}−1/{IL10},
where the braces around a constituent designate measurement of such constituent and the constituents are a subset of the Inflammation Gene Expression Panel of Table 1.
Just as a baseline profile data set, discussed above, can be used to provide an appropriate normative reference, and can even be used to create a Calibrated profile data set, as discussed above, based on the normative reference, an index that characterizes a Gene Expression Profile can also be provided with a normative value of the index function used to create the index. This normative value can be determined with respect to a relevant population, so that the index may be interpreted in relation to the normative value. The relevant population may have in common a property that is at least one of age group, gender, ethnicity, geographic location, diet, medical disorder, clinical indicator, medication, physical activity, body mass, and environmental exposure.
As an example, the index can be constructed, in relation to a normative Gene Expression Profile for a population of healthy subjects, in such a way that a reading of approximately 1 characterizes normative Gene Expression Profiles of healthy subjects. Let us further assume that the biological condition that is the subject of the index is inflammation; a reading of 1 in this example thus corresponds to a Gene Expression Profile that matches the norm for healthy subjects. A substantially higher reading then may identify a subject experiencing an inflammatory condition. The use of 1 as identifying a normative value, however, is only one possible choice; another logical choice is to use 0 as identifying the normative value. With this choice, deviations in the index from zero can be indicated in standard deviation units (so that values lying between −1 and +1 encompass 90% of a normally distributed reference population. Since we have found that Gene Expression Profile values (and accordingly constructed indices based on them) tend to be normally distributed, the 0-centered index constructed in this manner is highly informative. It therefore facilitates use of the index in diagnosis of disease and setting objectives for treatment. The choice of 0 for the normative value, and the use of standard deviation units, for example, are illustrated in
Acute Inflammatory Index to Assist in Analysis of Large, Complex Data Sets. In one embodiment of the invention the index value or algorithm can be used to reduce a complex data set to a single index value that is informative with respect to the inflammatory state of a subject. This is illustrated in
Use of acute inflammation index or algorithm to monitor a biological condition of a sample or a subject. The inflammatory state of a subject reveals information about the past progress of the biological condition, future progress, response to treatment, etc. The Acute Inflammation Index may be used to reveal such information about the biological condition of a subject. This is illustrated in
The results of the assay for inflammatory gene expression for each day (shown for 24 genes in each row of
Use of the acute inflammatory index to set dose, including concentrations and timing, for compounds in development or for compounds to be tested in human and non-human subjects as shown in
Use of the acute inflammation index to characterize efficacy, safety, and mode of physiological action for an agent, which may be in development and/or may be complex in nature. This is illustrated in
Development and use of population normative values for Gene Expression Profiles.
The consistency between gene expression levels of the two distinct populations is dramatic. Both populations show gene expressions for each of the 48 loci that are not significantly different from each other. This observation suggests that there is a “normal” expression pattern for human inflammatory genes, that a Gene Expression Profile, using the Inflammation Gene Expression Panel of Table 1 (or a subset thereof) characterizes that expression pattern, and that a population-normal expression pattern can be used, for example, to guide medical intervention for any biological condition that results in a change from the normal expression pattern.
In a similar vein,
As remarkable as the consistency of data from the two distinct normal populations shown in
In consequence of these principles, and in various embodiments of the present invention, population normative values for a Gene Expression Profile can be used in comparative assessment of individual subjects as to biological condition, including both for purposes of health and/or disease. In one embodiment the normative values for a Gene Expression Profile may be used as a baseline in computing a “calibrated profile data set” (as defined at the beginning of this section) for a subject that reveals the deviation of such subject's gene expression from population normative values. Population normative values for a Gene Expression Profile can also be used as baseline values in constructing index functions in accordance with embodiments of the present invention. As a result, for example, an index function can be constructed to reveal not only the extent of an individual's inflammation expression generally but also in relation to normative values.
Consistency of expression values, of constituents in Gene Expression Panels, over time as reliable indicators of biological condition.
Although the baseline in
Frozen samples were shipped to the central laboratory at Source Precision Medicine, the assignee herein, in Boulder, Colo. for determination of expression levels of genes in the 48-gene Inflammation Gene Expression Panel of Table 1. The blood samples were thawed and RNA extracted according to the manufacturer's recommended procedure. RNA was converted to cDNA and the level of expression of the 48 inflammatory genes was determined. Expression results are shown for 11 of the 48 loci in
In
Each of
Remarkably, these examples show a measurement, derived from the assay of blood taken from a subject, pertinent to the subject's arthritic condition. Given that the measurement pertains to the extent of inflammation, it can be expected that other inflammation-based conditions, including, for example, cardiovascular disease, may be monitored in a similar fashion.
These data support our conclusion that Gene Expression Profiles with sufficient precision and calibration as described herein (1) can determine subpopulations of individuals with a known biological condition; (2) may be used to monitor the response of patients to therapy; (3) may be used to assess the efficacy and safety of therapy; and (4) may used to guide the medical management of a patient by adjusting therapy to bring one or more relevant Gene Expression Profiles closer to a target set of values, which may be normative values or other desired or achievable values. We have shown that Gene Expression Profiles may provide meaningful information even when derived from ex vivo treatment of blood or other tissue. We have also shown that Gene Expression Profiles derived from peripheral whole blood are informative of a wide range of conditions neither directly nor typically associated with blood.
Furthermore, in embodiments of the present invention, Gene Expression Profiles can also be used for characterization and early identification (including pre-symptomatic states) of infectious disease, such as sepsis. This characterization includes discriminating between infected and uninfected individuals, bacterial and viral infections, specific subtypes of pathogenic agents, stages of the natural history of infection (e.g., early or late), and prognosis. Use of the algorithmic and statistical approaches discussed above to achieve such identification and to discriminate in such fashion is within the scope of various embodiments herein.
The present application is a continuation of U.S. application Ser. No. 11/158,504, filed Jun. 22, 2005, which is a continuation of U.S. application Ser. No. 10/291,856, filed Nov. 8, 2002, which in turn claims priority to U.S. Application Ser. No. 60/348,213, filed Nov. 9, 2001, U.S. Application Ser. No. 60/340,881, filed Dec. 7, 2001, U.S. Application Ser. No. 60/369,633, filed Apr. 3, 2002, and U.S. Application Ser. No. 60/376,997, filed Apr. 30, 2002. The contents of each of these applications are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 60348213 | Nov 2001 | US | |
| 60340881 | Dec 2001 | US | |
| 60369633 | Apr 2002 | US | |
| 60376997 | Apr 2002 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11158504 | Jun 2005 | US |
| Child | 12609578 | US | |
| Parent | 10291856 | Nov 2002 | US |
| Child | 11158504 | US |
