US20130280171A1

US20130280171A1 - Method to optimize the treatment of patients with biological drugs

Info

Publication number: US20130280171A1
Application number: US13/997,069
Authority: US
Inventors: Ainhoa Ruiz Del Agua; Antonio Martinez Martinez; Daniel Nagore Casas; Laureano SIMON BUELA
Original assignee: Proteomika SL
Current assignee: Progenika Biopharma SA
Priority date: 2010-12-22
Filing date: 2011-12-22
Publication date: 2013-10-24
Also published as: EP2490024A1; EP2656075A1; US20170102394A1; ES2526597T3; WO2012085228A1; KR20140044769A; DK2656075T3; EP2656075B1; US10215762B2

Abstract

The invention relates to the field of personalized therapy and, in particular, to a method for classifying a patient suffering from rheumatoid arthritis as a responder or as a non-responder patient to a treatment based on a biological drug.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Phase application of PCT International Application No. PCT/EP2011/073836, filed Dec. 22, 2011, and claims priority to European Patent Application No. EP 10382346.4, filed Dec. 22, 2010, the disclosures of which are incorporated by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates to the field of personalized therapy and, in particular, to a method for classifying a patient suffering from rheumatoid arthritis as a responder or as a non-responder patient to a treatment based on a biological drug selected from infliximab and adalimumab.

BACKGROUND OF THE INVENTION

The use of biological drugs has increased during the last years. For example, the TNF-alpha neutralizing antibodies are increasingly being used to treat diseases with a strong inflammatory background like rheumatoid arthritis (RA) and Inflammatory Bowel Disease (IBD).
Chronic inflammatory diseases represent a group of heterogeneous conditions characterized by an elevated production of cytokines, molecules which are essential for an organism's immune response, that play a critical role in the pathology of these diseases. Among the many cytokines Tumor Necrosis Factor alpha (TNF-alpha) is a key player due to its role in initiating the cascade of inflammatory processes and thus for triggering the development of disease symptoms in individuals suffering from an inflammatory disease.
The latest generation of biological drugs for the treatment of inflammatory diseases is based on antibody constructs that exert their effect by binding to TNF-alpha thus blocking initiation of the inflammatory cascade. While potentially very effective the use of these drugs requires the patient's response to the treatment to be closely monitored in order, if necessary, to guide the treatment regime.
In practice the response to treatment of patients with autoimmune and inflammatory diseases is monitored based on a number of clinical variables that reflect aspects of the disease process. Increasing the uniformity and consistency of methods used to measure patient response to treatment with anti-TNF-alpha biological drugs will help in optimizing dosing and contribute to a better use of expensive therapeutics by health care providers for the benefit of their patients.
Due to their structure and nature anti-TNF-alpha biological drugs are highly immunogenic. Unfortunately an immune response in the patient against biological drugs can dramatically reduce the efficacy of treatment.
Therefore, there is a need in the art for methods suitable for the determination of the patient response to a treatment based in a biological drug that are more specific than the conventional methods, and particularly for methods suitable for determining the response of a patient suffering from rheumatoid arthritis to a treatment based in an anti-TNF-alpha biological drug selected from infliximab and adalimumab.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1. Infliximab bioavailability and immunogenicity profiles over one year of treatment (top). The average values are shown for the group of patients showing no response to infliximab. ΔDAS28 is indicated for each infusion time (bottom). ΔDAS28 does not increase over the year of treatment (bottom). The horizontal line in the bottom panel indicates the ΔDAS28=1.2 threshold.

FIG. 2. Infliximab bioavailability and immunogenicity profiles over one year of treatment (top). The average values are shown for the group of patients showing response to infliximab. ΔDAS28 is indicated for each infusion time (bottom). ΔDAS28 does not increase over the year of treatment (bottom). The horizontal line in the bottom panel indicates the ΔDAS28=1.2 threshold.

FIG. 3. DAS28 as a function of bioavailability (infliximab concentration) and immunogenicity (antibody against infliximab) variables.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

The term “antibody” (also known as immunoglobulins, abbreviated Ig), as used herein is intended to gamma-globulin proteins that are found in blood or other bodily fluids of vertebrates, and that can bind to a target in an specific way. They are typically made of basic structural units, each with two large heavy chains and two small light chains, to form, for example, monomers with one unit, dimers with two units or pentamers with five units. The antibodies that can be used in the present invention as biological drugs, directed to different targets, are commercial products or can be obtained by conventional methods known by the person skilled in the art. Also antibody fragments can be used. An antibody fragment is a fragment of an antibody such as, for example, Fab, F(ab′)2, Fab′, scFv, diabodies, etc. Various techniques have been developed for the production of antibody fragments. Traditionally, these fragments were derived via proteolytic digestion of intact antibodies but more recently these fragments can be produced directly by recombinant host cells. Papain digestion of antibodies produces two identical antigen-binding fragments, called “Fab” fragments, each with a single antigen-binding site, and a residual “Fc” fragment. Pepsin treatment yields an F(ab′)2 fragment that has two antigen-binding sites and is still capable of cross-linking antigen. “Fv” is the minimum antibody fragment which contains a complete antigen-recognition and antigen-binding site. Fab′ fragments differ from Fab fragments by the addition of a few residues at the carboxy terminus of the heavy chain CHI domain including one or more cysteines from the antibody hinge region. Other chemical couplings of antibody fragments are also known. A single chain Fv (scFv) fragment comprises the VH and VL domains of an antibody, wherein these domains are present in a single polypeptide chain, and may be monospecific or bispecific. The term “diabodies” refers to small antibody fragments with two antigen-binding sites, which fragments comprise a heavy-chain variable domain (VH) connected to a light chain variable domain (VL) in the same polypeptide chain (VH-VL).
By “anti-TNF-alpha for “anti-TNF-α”, or “anti-TNF-a” or simply “anti-TNF”) therapy (or treatment)” is meant the administration to a patient of a biological drug or biological molecule (biopharmaceutical) capable of blocking, inhibiting, neutralizing, preventing receptor binding, or preventing TNFR activation by TNF-alpha. TNFR (“tumor necrosis factor receptor”), or death receptor, is a cytokine receptor that binds tumor necrosis factors (e.g., TNF-alpha) (Locksley R M, et al. 2001. Cell 104 (4): 487-501). Illustrative, non-limitative examples of such biological drugs include inhibitory antibodies against TNF-alpha as well as compounds, other than antibodies, capable of binding to TNF-alpha, e.g., proteins, peptides, small chemical molecules, etc.
The term “biological drug”, as used herein, refers to any substance made or obtained from a living organism or its products that is used in the prevention, diagnosis or treatment of a pathology, e.g., a human pathology, like antibodies such as IgG-like antibodies, Fab fragments, etc.; thus, a biological drug or biopharmaceutical is a medical drug produced using biotechnology, for example, a protein (including antibodies), a nucleic acid (DNA, RNA or antisense oligonucleotides), used for therapeutic or in vivo diagnostic purposes, and, generally are produced by means other than direct extraction from a native (non-engineered) biological source.
The term “dose” or “therapeutically effective amount” is used herein to mean an amount sufficient to prevent, and preferably reduce by at least about 25 percent, more preferably by at least 50 percent, most preferably by at least 90 percent, a clinically significant change in a feature of pathology. As related to the present invention, the term may also mean an amount sufficient to ameliorate or reverse one or more symptoms associated with a disease.
By “rheumatoid arthritis” or “RA” is meant a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium (synovitis) secondary to hyperplasia of synovial cells, excess synovial fluid, and the development of pannus in the synovium. The pathology of the disease process often leads to the destruction of articular cartilage and ankylosis of the joints. Rheumatoid arthritis can also produce diffuse inflammation in lungs, pericardium, pleura, and sclera, and also nodular lesions, most common in subcutaneous tissue under the skin. Although the cause of RA is unknown, autoimmunity plays a pivotal role in both its chronicity and progression, and RA is considered as a systemic autoimmune disease.
The term “patient”, as used herein, refers to all animals classified as mammals and includes, but is not restricted to, domestic and farm animals, primates and humans, e.g., human beings, non-human primates, cows, horses, pigs, sheep, goats, dogs, cats, or rodents. Preferably, the patient is a male or female human of any age or race.
The term “sample”, as used herein, relates to any sample which can be obtained from the patient, namely, a sample susceptible of containing antibodies. Thus, the present method can be applied to practically any type of biological sample from a patient, such as a biopsy sample, tissue, cell or fluid, e.g., blood, brain extracts, cerebral spinal fluid (CSF), milk, mucus, plasma, saliva, semen, serum, sputum, sweat, tears, and the like. In a particular embodiment, said sample is selected from blood, plasma or serum.
The term “TNF-alpha” (abbreviated herein as “TNF-α”, “TNFa” or simply “TNF”), as used herein, is intended to refer to a human cytokine that exists as a 17 kD secreted form and a 26 kD membrane associated form, the biologically active form of which is composed of a trimer of noncovalently bound 17 kD molecules. The sequence of human TNF-alpha is shown in CAA26669.1 (SEQ ID NO: 1). The term “TNF-alpha” as used herein not only includes the human gene and protein but also their orthologues from other species such as dogs, mice, rats, etc., as well as functionally equivalent variants thereof.

Method of the Invention

The authors of the present invention have now found that a specific concentration of a circulating biological drug (e.g., infliximab, adalimumab, etc.) together with, optionally, a specific concentration of antibodies to said biological drug (anti-biological drug antibodies), particularly as determined in a blood sample from a patient, said patient suffering from rheumatoid arthritis and being treated with said biological drug, is associated with the patient's response to the treatment with said biological drug.
This information would allow physicians (medical doctors) to follow more closely their patients' response to treatment and to make informed decisions over treatment. These biological variables have been clinically validated to show utility in correlating both the levels of circulating biological drugs and the levels of antibodies against said biological drugs with the efficacy of treatment based on the patients Disease Activity Score (DAS28) used to follow up the disease in patients.
Thus, in an aspect, the present invention refers to a method, hereinafter referred to as the “method of the invention”, for classifying a patient suffering from rheumatoid arthritis as a responder or as a non-responder patient to a treatment, said treatment comprising the administration to said patient of a biological drug selected from the group consisting of infliximab and adalimumab that is periodically administered by repetitive administrations, and wherein said patient has received at least one dose from said biological drug, said method comprising the steps of:

- a) determining the concentration of the circulating biological drug in a sample from said patient at a time t1 wherein said t1 corresponds to a time point within the period of time between two successive administrations of said biological drug; and
- b) comparing the concentration of the circulating biological drug at said t1 with a Reference Value 1 (RV1),
  wherein
- RV1 is a therapeutic efficiency cut-off value of the concentration of the circulating biological drug; and
  wherein if the concentration of the circulating biological drug is lower than RV1, then said patient is classified as a non-responder patient to said treatment, and wherein if the concentration of the circulating biological drug is equal to, or higher than, RV1, then said patient is classified as a responder patient to said treatment, and
  wherein if the biological drug is infliximab, then RV1 is 1.5 μg/ml; and
  wherein if the biological drug is adalimumab, then RV1 is 0.8 μg/ml.

In the method of the invention, the pathology which is treatable with a biological drug is a pathology wherein TNF-alpha is involved, specifically rheumatoid arthritis. The patient is subjected to an anti-TNF-alpha treatment comprising the administration to said patient of a biological drug selected from the group consisting of infliximab and adalimumab that is periodically administered by repetitive administrations, said biological drug being capable of blocking, inhibiting, neutralizing, preventing receptor binding, or preventing TNFR activation by TNF-alpha.
Said biological drug is an antibody or a fragment thereof; particularly, an inhibitory anti-TNF-alpha antibody. An “inhibitory anti-TNF-alpha antibody” or “inhibitory antibody against TNF-alpha”, as used herein, refers to an antibody which is capable of preventing TNFR activation by TNF-alpha and thus the initiation of the inflammation cascade. A “tumor necrosis factor receptor (TNFR)”, or death receptor, is a cytokine receptor that binds tumor necrosis factors (e.g., TNF-alpha) (Locksley R M, et al. 2001. Cell 104 (4): 487-501). The determination of the inhibiting capacity on the TNFR activation by TNF-alpha can be detected using standard assays to measure the activation of TNFR such as the ones described by Solorzano et al. (Solorzano C. C. et al. 1998. J Appl Physiol 84: 1119-1130) or by Hyunil et al. (Hyunil Ha et al. 2009. Current Protocols in Immunology Chapter 11 Unit11.9D).
Inhibitory antibodies, or fragments thereof, against TNF-alpha may be readily available, or may be readily produced by using conventional molecular biology techniques. By illustrative, using immunogens derived from, for example, the TNF-alpha molecule it is possible to obtain anti-protein/anti-peptide antisera or monoclonal antibodies by using standard protocols (see, for example, “Antibodies: A Laboratory Manual”, ed. by Harlow and Lane (Cold Spring Harbor Press: 1988)). A mammal, such as a mouse, a hamster or rabbit can be immunized with an immunogenic form of the peptide (e.g., TNF-alpha or an antigenic fragment thereof, which is capable of eliciting an antibody response). Techniques for conferring immunogenicity on a protein or peptide, include conjugation to carriers or other techniques, are well known in the art. An immunogenic portion of a polypeptide can be administered in the presence of adjuvant. The progress of immunization can be monitored by detection of antibody titers in plasma or serum. Standard ELISA or other immunoassays can be used with the immunogen as antigen to assess the levels of antibodies. In a preferred embodiment, the antibodies forming part of the compositions of the invention are immuno-specific for antigenic determinants of TNF-alpha (or a variant at least 80%, 85%, 90%, 95%, or 98% identical thereto). In certain embodiment, the immunospecific subject antibodies do not substantially cross react with a non-vertebrate (such as yeast) TNF-alpha related protein. By “not substantially cross react” it is meant that the antibody has a binding affinity for a non-homologous protein which is at least one order of magnitude, more preferably at least 2 orders of magnitude, and even more preferably at least 3 orders of magnitude less than the binding affinity of the antibody for a TNF-alpha.
Thus, the antibody which can be used for the purposes of the instant invention as an inhibitory antibody against TNF-alpha is capable of binding to an epitope of TNF-alpha; typically, at least 6, 8, 10, or 12, contiguous amino acids are required to form an epitope, however, epitopes which involve non-contiguous amino acids may require more, e.g., at least 15, 25, or 50 amino acid. Illustrative TNF-alpha inhibitory antibodies include, for example, polyclonal antibodies, monoclonal antibodies (mAbs), Fab and scFv fragments thereof, bispecific antibodies, heteroconjugates, human and humanized antibodies, etc. Such antibodies may be produced in a variety of ways, including hybridoma cultures, recombinant expression in bacteria or mammalian cell cultures, and recombinant expression in transgenic animals. Also antibodies can be produced by selecting a sequence from a library of sequences expressed in display systems such as filamentous phage, bacterial, yeast or ribosome. There is abundant guidance in the literature for selecting a particular production methodology (see, e.g., Chadd and Chamow, Curr. Opin. Biotechnol., 12:188-194 (2001).
The inhibitory antibody against TNF-alpha is an inhibitory mAb to TNF-alpha including, but not limited to, the antibodies sold under the generic names of Infliximab (Remicade®, Johnson and Johnson; described in U.S. Pat. No. 5,656,272), Adalimumab (Humira®, Abbott Laboratories, a human anti-TNF-alpha mAb described in U.S. Pat. No. 6,090,382 as D2E7), etc., and antibodies in clinical development such as Golimumab (or CNTO 148; WO 02/12502), etc. Further examples of anti-TNF-alpha antibodies, or fragments thereof, include CDP571 (a humanized monoclonal anti-TNF-alpha IgG4 antibody), CDP 870 (a humanized monoclonal anti-TNF-alpha antibody fragment), an anti-TNF dAb (Peptech), etc.
Additional antibodies to human TNF-alpha and fragments thereof are disclosed in U.S. Pat. No. 6,593,458, U.S. Pat. No. 6,509,015, U.S. Pat. No. 6,498,237, U.S. Pat. No. 6,451,983, U.S. Pat. No. 6,448,380, U.S. Pat. No. 6,258,562, U.S. Pat. No. 6,090,382, U.S. Pat. No. 7,223,394 and U.S. patent application US 2003/0219438 A1.
In a preferred embodiment, the biological drug is an inhibitory mAb to TNF-alpha selected from the group consisting of infliximab and adalimumab.
The method of the invention allows for classifying a patient as a responder or as a non-responder patient to a treatment, said treatment comprising the administration to said patient of a biological drug selected from infliximab and adalimumab that is periodically administered by repetitive administrations, wherein said patient suffers from rheumatoid arthritis which is treatable with said biological drug under said treatment and wherein said patient has received at least one dose from said biological drug.
According to the method of the invention, the concentration of the circulating biological drug in a sample from the patient under study is determined at a time t1, wherein said time t1 corresponds to a time point within the period of time between two successive administrations of said biological drug [step a)]. This step is intended to determine the bioavailability of the biological drug administered to the patient under study.
The term “t1” corresponds to a time point within the period of time between two successive administrations of said biological drug to the patient. The period of time between two successive administrations, hereinafter referred to as “period of time ti-tj”, may vary within a broad range, for example, said period of time may comprise, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, or even more days; typically, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or even more weeks, or 1, 2, 3, 4, 5, 6 or even more months. In a particular embodiment, t1 is a time point in the first half of said period of time ti-tj; in another particular embodiment, t1 is a time point in the second half of said period of time ti-tj; and, in another particular embodiment, t1 is a time point around the half of said period of time ti-tj. By illustrative, the period of time ti-tj may be 4 weeks and t1 may be a time point within the first half of said period of time ti-tj (e.g., day 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14 after the day of the prior administration (ti)); alternatively, the period of time ti-tj may be 4 weeks and t1 may be a time point within the second half of said period of time ti-tj (e.g., day 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 after the day of the prior administration (ti)); or alternatively, the period of time ti-tj may be 4 weeks and t1 may be a time point around the half of said period of time ti-tj (e.g., day 13, 14, 15, 16, or 17 after the day of the prior administration (ti)). In a particular embodiment, said period of time ti-tj is 4 weeks and t1 is a time point within the second half of said period of time ti-tj, i.e., within the last two weeks of said period of time ti-tj, preferably within the last week of said period of time ti-tj, more preferably 6, 5, 4 or 3 days before the day of the following administration (tj).
The precise dose to be administered to the patient will depend, among other features, on the route of administration, and the seriousness of the disease or disorder to be treated, and should be decided according to the judgment of the physician and the patient's needs. Generally, the biological drug is administered to the patient in need of treatment at a dose of approximately 0.005 mg per kilogram of body weight to approximately 50 mg per kilogram of body weight; typically the dose ranges from approximately 0.5 mg per kilogram of body weight to approximately 15 mg per kilogram of body weight. In a preferred embodiment the dose is between 3 and 5 mg/kg intravenously. In another preferred embodiment the dose is approximately 0.7 mg/kg subcutaneously.
The term “circulating biological drug” as used herein, relates to the biological drug that is present in a fluid of the patient's body (e.g., blood, serum, milk, etc.) and can be detected by using standard methods.
The biological drug of the method of the invention is an antibody. The concentration of an antibody can be determined by practically any method known by the person skilled in the art, such as, an immunoassay, for example, an ELISA (Enzyme-Linked Immunosorbent Assay), ELISA Using Slope Correction, RIA (radioimmunoassay), competitive EIA (competitive enzyme immunoassay), DAS-ELISA (double antibody sandwich-ELISA), bridging-ELISA, techniques based on the use of protein or antibody microarrays, technologies based on discrete microparticles, assays based on the precipitation of colloidal gold, affinity chromatography techniques, ligand binding assays, lectin binding assays, biosensors, etc., preferably by an immunoassay. In a particular embodiment, the concentration of the circulating antibodies (biological drug) is measured by an ELISA, as it is shown in the examples of the present invention.
In a second step [step b)], the method of the invention comprises comparing the concentration of the circulating biological drug at said t1 with a Reference Value 1 (RV1) wherein RV1 is a therapeutic efficiency cut-off value of the concentration of the circulating biological drug.
The term “therapeutic efficiency cut-off value of the concentration of the circulating biological drug” (RV1), as used herein, relates to the concentration of the biological drug that is available in the circulating blood for which no positive titer of antibody against the biological drug is measured in the same sample. The term “no positive titer” as used herein is equivalent to a value below RV2, the term “RV2” being defined below.
Further, according to the method of the invention, if the concentration of the circulating biological drug is lower than RV1, then said patient is classified as a non-responder patient to said treatment/biological drug.
On the contrary, if a t1, the concentration of the circulating biological drug is equal to, or higher than, RV1, then said patient is classified as a responder patient to said treatment/biological drug.
In a more specific embodiment, the biological drug is infliximab and RV1 is 1.5 μg/ml. In another more specific embodiment, the biological drug is adalimumab and RV1 is 0.8 μg/ml.
In a particular embodiment, the method of the invention further comprises, in addition to the determination of the concentration of said circulating biological drug (infliximab or adalimumab), the determination of the concentration of antibodies to said biological drug; thus in a particular embodiment, the method of the invention comprises the steps of:

- 1) determining the concentration of the circulating biological drug in a sample from said patient at a time t1 wherein said t1 corresponds to a time point within the period of time between two successive administrations of said biological drug,
- 2) determining the concentration of antibodies against said biological drug in a sample from said patient at a time; and
- 3) comparing the concentration of the circulating biological drug at said t1 with a Reference Value 1 (RV1) and the concentration of antibodies against said biological drug at said time t1 with a Reference Value 2 (RV2),
  wherein
- RV1 is a therapeutic efficiency cut-off value of the concentration of the circulating biological drug; and
- RV2 is the cut-off value of the concentration of said antibody against the biological drug as determined in a group of treatment-naïve individuals by the same assay as that used for determining the concentration of the antibody against the biological drug in step 2), and
  wherein if the concentration of the circulating biological drug is lower than RV1 and the concentration of antibodies against said biological drug is higher than RV2, then said patient is classified as a non-responder patient to said treatment, and
  wherein if the concentration of the circulating biological drug is equal to, or higher than, RV1 and the concentration of antibodies against said biological drug is equal to, or lower than, RV2, then said patient is classified as a responder patient to said treatment; and
  wherein if the biological drug is infliximab, then RV1 is 1.5 μg/ml; and
  wherein if the biological drug is adalimumab, then RV1 is 0.8 μg/ml.

Said particular embodiment comprises a first step 1) which is equivalent to the first step [step a)] previously described for the method of the invention. In a second step [step 2) of this particular embodiment], the method of the invention comprises determining the concentration of antibodies against said biological drug in a sample from said patient at said time t1. This step is intended to determine the immunogenicity of the biological drug administered to the patient under study. Examples 1 and 2 of the present invention show a method including said step. This step is not necessary in order to classify a patient as a responder or non-responder to a biological drug since it is sufficient to determine the levels of concentration of the circulating biological drug in a sample of said patient to obtain a good correlation with the clinical response. This is shown in Examples 3 and 4 of the present invention.
The term “antibody against a biological drug” as used herein, relates to any antibody that the immunosystem of the patient treated with said biological drug produces that binds specifically to said biological drug. Types of antibodies include IgA, IgD, IgE, IgG and IgM. The concentration of antibodies against a biological drug can be measured by any method known by the person skilled in the art, for example, an immunoassay, e.g., ELISA, ELISA Using Slope Correction, RIA, competitive ETA, DAS-ELISA, bridging-ELISA, techniques based on the use of antibody microarrays, etc., as it has been previously discussed. In a particular embodiment, the concentration of the antibodies against a biological drug is measured by an ELISA, as it is shown in the Examples 1 and 2 of the present invention.
If low amount of antibodies against a biological drug are present in the sample, these can be complexed with the biological drug, and, therefore, they would not be detected in the determination of the antibodies against the biological drug (i.e., immunogenicity determination). This is a phenomenon called “drug interference”. In order to measure the antibody titer in the presence of drug-antibody complexes, complexes can be disaggregated by using, for example, an acid dissociation protocol. In a particular embodiment, the samples can be treated with an acid (e.g., acetic acid) prior to perform the immunogenicity determination, such as it is mentioned in the accompanying examples.
In the third step [step 3) of this particular embodiment], the method of the invention comprises comparing the concentration of the circulating biological drug at said t1 with a Reference Value 1 (RV1) and the concentration of antibodies against said biological drug at said time t1 with a Reference Value 2 (RV2), wherein RV1 is a therapeutic efficiency cut-off value of the concentration of the circulating biological drug, and RV2 is the cut-off value of the concentration of said antibody against the biological drug as determined in a group of treatment-naïve individuals by the same assay as that used for determining the concentration of the antibody against the biological drug in step b) of said particular embodiment).
The term “therapeutic efficiency cut-off value of the concentration of the circulating biological drug” (RV1), as defined above, relates to the concentration of the biological drug that is available in the circulating blood for which no positive titer of antibody against the biological drug is measured in the same sample. The term “no positive titer” as used herein is equivalent to a value below RV2, the term “RV2” being defined below, i.e., the cut-off value of the immunogenicity determination as determined in a group of treatment-naïve individuals by the same assay as that used for determining the concentration of the antibody against the biological drug in step 2) [i.e., if the concentration of antibodies against said biological drug is measured by a conventional ELISA assay in step 2), the concentration of antibodies against said biological in the group of treatment-naïve individuals is also determined under the same conditions by using the same conventional ELISA assay]. In order to generate RV1, ideally the concentrations of the circulating biological drug in a group of patients treated with the biological drug are used. Preferably at least 2, more preferably 2, 3, 10, 20, 40, 100 or even more patients are used.
In a more specific embodiment, the biological drug is infliximab and RV1 is 1.5 μg/ml. In another more specific embodiment, the biological drug is adalimumab and RV1 is 0.8 μg/ml.
The term “cut-off value of the concentration of said antibody against the biological drug as determined in a group of treatment-naïve individuals by the same assay as that used for determining the concentration of the antibody against the biological drug in step 2)” (RV2) is understood in the present invention the value that defines the background measurements of the assay used for determining the concentration of the antibody against the biological drug in step 2), what means, that above said value, the measurements are true positive values since are above the background or noise threshold of the method used.
The term “treatment-naïve individuals” as used herein, relates to subjects who are new (naïve) to the biological drug therapy, that is, that were never treated before with said therapy. Thus, those subjects should not present antibodies against the biological drug and thus the concentration measured in a group of said subjects could be used to determine the cut-off value of the immunogenicity determination. The group of naïve subjects is preferably formed by more than 1, preferably 2 or more, more preferably 3 or more, most preferably 4, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 500, or even more treatment-naïve individuals. The cut off-value is then calculated as the mean of the values obtained from each of the treatment-naïve individuals.
In a particular embodiment, the immunoassay is an ELISA. In a more specific embodiment, the immunoassay is an ELISA, the biological drug is infliximab and RV2 is 150 ng/ml. In another more specific embodiment, the immunoassay is an ELISA, the biological drug is adalimumab and RV2 is 32 ng/ml.
Further, according to said particular embodiment of the method of the invention, if the concentration of the circulating biological drug is lower than RV1 and the concentration of antibodies against said biological drug is higher than RV2, then said patient is classified as a non-responder patient to said treatment/biological drug.
On the contrary, if a t1, the concentration of the circulating biological drug is equal to, or higher than, RV1 and the concentration of antibodies against said biological drug is equal to, or lower than, RV2, then said patient is classified as a responder patient to said treatment/biological drug.
The term “responder patient” as used herein, relates to patients for which the predicted response to the treatment/biological drug is positive. Similarly, the term “non-responder patient” as used herein, relates to patients for which the predicted response to the treatment/biological drug is negative.
The term “predicted response” or similar, as used herein refers to the determination of the likelihood that the patient will respond either favorably or unfavorably to a given therapy/biological drug. Especially, the term “prediction”, as used herein, relates to an individual assessment of any parameter that can be useful in determining the evolution of a patient. As it will be understood by those skilled in the art, the prediction of the clinical response to the treatment with a biological drug, although preferred to be, need not be correct for 100% of the subjects to be diagnosed or evaluated. The term, however, requires that a statistically significant portion of subjects can be identified as having an increased probability of having a positive response. Whether a subject is statistically significant can be determined without further effort by the person skilled in the art using various well known statistic evaluation tools, e.g., determination of confidence intervals, p-value determination, Student's t-test, Mann-Whitney test, etc. Details are found in Dowdy and Wearden, Statistics for Research, John Wiley & Sons, New York 1983. Preferred confidence intervals are at least 50%, at least 60%, at least 70%, at least 80%, at least 90% at least 95%. The p-values are, preferably, 0.2, 0.1 or 0.05.
The term “clinical response”, as used herein, refers to the response to a biological drug of the subject suffering from a pathology which is treatable with said biological. Standard criteria may vary from disease to disease.
Patients achieving complete or partial response are considered “responders”, and all other patients are considered “non-responders”.
The response in individual patients may be characterized as a complete response, a partial response, stable disease, and progressive disease, as these terms are understood in the art. Thus, the method of the invention allows for classifying a patient as a responder or as a non-responder patient to a treatment, said treatment comprising the administration to said patient of a biological drug selected from the group consisting of infliximab and adalimumab that is periodically administered by repetitive administrations, wherein said patient suffers from rheumatoid arthritis which is treatable with said biological drug under said treatment and wherein said patient has received at least one dose from said biological drug.
In the case of rheumatoid arthritis, the standard used is the Disease Activity Score determination (DAS28, see table 1). DAS28 is determined according to the European League against Rheumatism (EULAR) (Aletaha D, et al. 2010. Ann. Rheum. Dis. 69 (9): 1580-8).
In a more particular embodiment, the biological drug is infliximab. Infliximab is a mAb anti-TNF-alpha which can be used for the treatment of, for example, psoriasis, Crohn's disease, ankylosing spondylitis, psoriatic arthritis, rheumatoid arthritis and ulcerative colitis. In another particular embodiment the biological drug is adalimumab. Adalimumab is a TNF-alpha inhibitor which can be used for the treatment of, for example, rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, Crohn's disease, moderate to severe chronic psoriasis and juvenile idiopathic arthritis. In a specific embodiment, said pathology of the patient to be treated by a biological drug is rheumatoid arthritis and said biological drug is infliximab, RV1 is 1.5 μg/ml and RV2 is 150 ng/ml (as determined by ELISA).
In another specific embodiment, said pathology of the patient to be treated by a biological drug is rheumatoid arthritis and said biological drug is adalimumab, RV1 is 0.8 μg/ml and RV2 is 32 ng/ml (as determined by ELISA).
The following examples illustrate the invention and should not be considered as limitative of the scope thereof.

EXAMPLES

The following methods were common to all the Examples (as applicable).

Methods

Sampling

Blood samples from patients (Examples 1 and 2) were collected before each infusion, and serum was obtained, aliquoted and stored at −20° C.

Analysis

An aliquot of each serum was defrozen. All sera were tested simultaneously for free biological drug concentration (bioavailability) and anti-biological drug antibodies (immunogenicity).

Bioavailability Analysis

An immunoassay was designed to specifically measure the concentration of the free biological drug (antibodies to human TNF-alpha infliximab or adalimumab) in the sera of patients. Briefly, a 96-well ELISA plate was coated with human recombinant TNF-alpha, whose amino acid sequence is shown in SEQ ID NO: 2, via a murine anti-TNF-alpha monoclonal antibody. Recombinant human TNF-alpha was obtained in Escherichia coli, by cloning into an expression vector. The protein was expressed as a fusion protein bearing a six histidine tag in its amino terminus and purified by affinity chromatography.
Sera were incubated in the plate in different serial dilutions and replicas. If the biological drug is present in the serum of the patient, it will bind to the fixed TNF-alpha. Detection of the bound biological drug takes place with a biotinylated monoclonal antibody to said biological drug (infliximab or adalimumab). After washing, the amount of bound biotinylated antibody can be measured by incubating with streptavidin-polyHRP (Fitzgerald Industries Limited), and after another washing step incubating with 3,3′,5,5′-tetramethylbenzidine (TMB), the substrate for horseradish peroxidase (HRP). If the result is positive a blue color will appear. The reaction is stopped with HCl, which changes the blue color into yellow. This yellow color can be measured in an ELISA reader at 450 nm. In parallel, a calibration standard curve is constructed using pure biological drug. This correlates the concentration of the biological drug to a given absorbance intensity. The concentration of free biological drug in the serum of each patient is obtained in micrograms per milliliter (μg/ml) of serum by extrapolation of the absorbance intensity in the calibration curve.

Immunogenicity Standard Analysis

A bridging immunoassay was designed to specifically measure the concentration of the immunoglobulins against the biological drug in the sera of patients. Briefly, a 96-well ELISA plate is coated with the biological drug. Sera are incubated in the plate in different serial dilutions and replicas. If anti-biological drug antibodies are present in the serum of the patient, they will bind to the fixed biological drug. Finally, biotinylated biological drug is added as a detection reagent. If anti-biological drug antibodies are present in the serum of the patient, the biotinylated biological drug will bind to them. After washing, the amount of anti-biological drug antibodies can be measured by incubating with streptavidin-polyHRP, and after another washing step incubating with TMB, the substrate for HRP. If the result is positive a blue color will appear. The reaction is stopped with HCl, which changes the blue color into yellow. This yellow color can be measured in an ELISA reader at 450 nm. In parallel, a calibration standard curve is constructed using serial dilutions of a serum sample with known concentration of anti-biological drug antibodies as a positive control. This correlates the concentration of the antibodies to a given absorbance intensity. The concentration of antibodies in the serum of each patient is obtained in arbitrary units per milliliter (AU/ml) of serum by extrapolation of the absorbance intensity in the calibration curve. For quantification purposes, in the case of infliximab, 1 AU/ml corresponds to 10 ng/ml of anti-infliximab antibodies, and, in the case of adalimumab, 1 AU/ml corresponds to 4 ng/ml of anti-adalimumab antibodies.
Immunogenicity Analysis with Acid Dissociation Protocol
If low amount of anti-biological drug antibodies are present in the sample, these can be complexed with the biological drug, and, therefore, they would not be detected in the immunogenicity analysis. This is a phenomenon called “drug interference”. In order to measure the antibody titer in the presence of biological drug-antibody complexes, complexes were disaggregated using an acid dissociation protocol. The samples were treated with acetic acid prior to the analysis, and the immunogenicity analysis was carried out as explained before.
Disease Activity Score determination (DAS28)
Disease Activity Score was determined by the rheumatologist according to the European League against Rheumatism (EULAR) criteria for every patient at each sampling point (Table 1). A high value of DAS28 indicates the progression of the disease. A low value of DAS28 indicates the remission of the disease.

TABLE 1

DAS28 cut-off values according to EULAR

	Status of disease	DAS28 ranges

	Remission	<1.6
	Low activity	<2.4
	Moderate activity	2.4 ≦ DAS28 ≦ 3.7
	High activity	>3.7

	Classification of clinical response. In rheumatoid arthritis patients, clinical response to the biological drug treatment was assessed according to DAS28 index. Definition of responder and non-responder was assessed one year after the initiation of the treatment with the corresponding drug.
	According to EULAR:
	patients were grouped as responders if: ΔDAS28 = DAS28_predose− DAS28_{1 year}≧ 1.2; and
	patients were grouped as non-responders if: ΔDAS28 = DAS28_predose− DAS28_{1 year}< 1.2

Bioavailability and Immunogenicity Cut-Off Values Determination

Pre-dose samples of 52 patients (infliximab) and 10 patients (adalimumab) were analysed in order to calculate the cut-off value of both the concentration of the biological drug (bioavailability cut-off) and the concentration of anti-biological drug antibodies (immunogenicity cut-off), which were defined as the average of the background signals of all the pre-dose sera plus 1.645 times the standard deviation of all the values.

Bioavailability and Immunogenicity Reference Values Determination

A reference value 1 (RV1) corresponds to the therapeutic efficiency threshold for each of the circulating biological drugs as detailed in the “Determination of the diagnostic cut-offs” sections for infliximab and adalimumab as shown in Examples 1 and 2. A reference value 2 (RV2) corresponds to the lowest positive titer of antibodies against each biological drug that can be quantified (expressed in units (U) or ng (nanograms) per milliliter) as detailed in the “Determination of the diagnostic cut-offs” sections for infliximab and adalimumab as shown in Examples 1 and 2.

Statistical Analysis

SigmaPlot v11.0 and SPSS v11.0 were used for data analysis. Samples did not follow a normal distribution according to Kolmogorov-Smirnov and Shapiro-Wilk tests. Therefore non-parametric tests were used for the subsequent analysis. Kendall's Tau and Spearman's Rho were used to study the correlation between variables. P values less than 0.05 were considered as statistically significant.

Example 1

Correlation of Bioavailability and Immunogenicity of Infliximab with the Clinical Response of Patients Suffering from Rheumatoid Arthritis

Subjects:
Rheumatoid arthritis (RA) patients, 75, fulfilling the criteria of the American College of Rheumatology (ACR) of 1987 (1987 ACR criteria) [Arnett F. et al. (1988). “The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis”. Arthritis Rheum. 31 (3): 315-24] and about to start treatment with infliximab, were enrolled consecutively. A total of 612 serum samples from said 75 patients suffering from RA were analysed.
Treatment:
Patients received doses of 3 mg/kg of infliximab (Remicade®) intravenously. The frequency of drug administration was as follows: first infusion on the first day of treatment (baseline), second infusion two weeks later, third infusion one month after the second, fourth infusion two months after the third, and subsequent infusions at eight weeks interval.
Evaluation of the Patient Clinical Response:
Disease Activity Score 28 (DAS28) was used to evaluate the clinical response of the patient according scores in Table 1. DAS28 is a validated method according to the European League against Rheumatism (EULAR) criteria. One year clinical response was determined as explained before.
Determination of Bioavailability and Immunogenicity of Infliximab:
Table 2 summarizes the average values of bioavailability and immunogenicity of infliximab.

TABLE 2

Average of infliximab bioavailability and immunogenicity.

	Infliximab	Immunogenicity
	bioavailability (μg/ml)	(antibodies against infliximab)

Sam-

Av-

(AU/ml)

ples	erage	SD	Cmin	Cmax	Average	SD	Cmin	Cmax

612	4.27	7.39	0.002	54.4	437.47	2490.69	1.000	45904.64

SD: standard deviation;
Cmin: minimum concentration;
Cmax: maximum concentration.

Further, Table 3 summarizes the average values of infliximab bioavailability and immunogenicity as a function of the treatment.

TABLE 3

Average of infliximab bioavailability and immunogenicity as a function of the treatment.

		Immunogenicity (antibodies against
Infusion	Infliximab bioavailability (μg/ml)	infliximab) (AU/ml)

number	Average	SD	Cmin	Cmax	N	Average	SD	Cmin	Cmax	N

0	0.002	0.000	0.002	0.002	35	1.00	0.00	1.00	1.00	35
1	23.17	9.67	5.05	48.59	36	1.00	0.00	1.00	1.00	36
2	11.31	9.34	0.002	38.99	37	1.91	3.30	1.00	15.00	37
3	2.87	3.95	0.002	14.87	34	42.50	130.26	1.00	718.92	34
4	1.58	2.57	0.002	11.88	29	200.68	477.53	1.00	1665.90	29
5	1.82	3.41	0.002	13.52	25	479.24	1705.36	1.00	8458.88	25
6	2.61	3.78	0.002	13.13	22	460.31	1226.83	1.00	4606.24	22
7	2.61	4.00	0.002	15.40	18	791.14	2324.35	1.00	9607.56	18
8	3.56	4.81	0.002	14.35	14	1516.52	5666.53	1.00	21204.28	14

SD: standard deviation;
Cmin: minimum concentration;
Cmax: maximum concentration;
N, number of patients.

Tables 4-6 provide individual values of infliximab bioavailability and immunogenicity as a function of the treatment for each patient.

TABLE 4

Individual values of circulating infliximab (IFX) and immunogenicity (antibodies). Infusion numbers 0 to 3
are shown.

Infusion number 0

Infusion number 1

Infusion number 2

Infusion number 3

	IFX	Antibodies		IFX	Antibodies		IFX	Antibodies		IFX	Antibodies
Patient	(μg/ml)	(AU/ml)	Patient	(μg/ml)	(AU/ml)	Patient	(μg/ml)	(AU/ml)	Patient	(μg/ml)	(AU/ml)

1	0.002	1.000	1	21.514	1.000	1	3.966	1.000	4	0.002	15.000
5	0.002	1.000	4	24.828	1.000	4	6.414	1.000	7	1.529	1.000
6	0.002	1.000	5	30.143	1.000	5	19.442	1.000	8	4.278	1.000
7	0.002	1.000	6	5.331	1.000	6	3.317	1.000
8	0.002	1.000	7	29.050	1.000	7	8.713	1.000	14	0.002	718.918
12	0.002	1.000	8	30.607	1.000	8	13.349	1.000	17	0.002	1.000
16	0.002	1.000	12	48.589	1.000	12	27.184	1.000	18	3.830	1.000
17	0.002	1.000	14	22.375	1.000	14	0.002	1.000	19	0.002	209.533
18	0.002	1.000	16	19.727	1.000	16	15.343	1.000	20	0.002	1.000
19	0.002	1.000	17	30.149	1.000	17	0.461	1.000	21	14.059	1.000
20	0.002	1.000	19	5.046	1.000	18	9.170	1.000	23	0.002	15.000
21	0.002	1.000	20	20.684	1.000	19	0.002	6.585	24	3.187	1.000
22	0.002	1.000	23	30.993	1.000	20	4.987	1.000	27	2.192	1.000
23	0.002	1.000	24	26.668	1.000	21	38.988	1.000	29	3.331	1.000
24	0.002	1.000	27	37.440	1.000	23	6.196	1.000	31	0.002	15.000
27	0.002	1.000	29	37.448	1.000	24	17.797	1.000	33	4.742	1.000
29	0.002	1.000	31	23.707	1.000	27	13.983	1.000	35	0.002	99.345
31	0.002	1.000	33	34.567	1.000	29	26.635	1.000	44	0.002	15.000
33	0.002	1.000	35	11.389	1.000	31	0.310	1.000	60	0.002	15.000
35	0.002	1.000	37	15.527	1.000	33	15.530	1.000	66	1.084	1.000
37	0.002	1.000	44	14.028	1.000	35	0.002	15.000	68	10.586	1.000
44	0.002	1.000	66	33.058	1.000	37	15.689	1.000	71	3.045	1.000
66	0.002	1.000	71	34.340	1.000	44	1.702	1.000	87	1.064	1.000
71	0.002	1.000	87	27.373	1.000	66	15.629	1.000	91	0.002	209.960
87	0.002	1.000	91	12.255	1.000	71	28.048	1.000	95	0.212	1.000
91	0.002	1.000	95	16.452	1.000	87	11.475	1.000	110	14.867	1.000
110	0.002	1.000	110	26.161	1.000	91	0.002	15.000	125	4.984	1.000
125	0.002	1.000	125	17.282	1.000	95	8.843	1.000	137	0.002	33.923
137	0.002	1.000	137	30.077	1.000	125	18.549	1.000	138	8.768	1.000
138	0.002	1.000	138	16.817	1.000	137	12.262	1.000	151	5.334	1.000
151	0.002	1.000	151	14.821	1.000	138	13.075	1.000	157	4.634	1.000
157	0.002	1.000	157	18.985	1.000	151	18.129	1.000	168	0.002	11.185
172	0.002	1.000	168	10.657	1.000	157	19.052	1.000	172	3.128	1.000
177	0.002	1.000	172	17.258	1.000	168	2.105	1.000	177	0.002	65.310
179	0.002	1.000	177	15.448	1.000	172	10.360	1.000	179	2.775	1.000
			179	23.144	1.000	177	1.433	1.000
						179	10.228	1.000

TABLE 5

Individual values of circulating infliximab (IFX) and immunogenicity (antibodies). Infusion numbers 4 to 7
are shown.

Infusion number 4

Infusion number 5

Infusion number 6

Infusion number 7

4	0.002	112.763	7	0.002	13.645	7	0.002	14.555	8	1.457	1.000
6	0.002	31.175	8	6.421	1.000	8	0.384	1.000	19	0.002	9607.560
7	0.040	1.000	18	0.002	1.000	19	0.002	4606.240	27	0.002	1.000
8	1.233	1.000	19	0.002	1676.180	27	0.002	35.580	29	2.255	1.000
14	0.002	1559.520	27	0.930	1.000	31	0.002	935.160	31	0.002	1352.732
17	0.002	200.373	29	0.807	1.000	33	12.269	1.000	33	8.662	1.000
18	4.579	1.000	31	0.002	297.668	44	0.002	15.000	44	0.002	15.000
19	0.002	1450.960	33	13.520	1.000	60	2.688	1.000	60	0.040	1.000
21	6.254	1.000	35	0.002	15.000	65	1.879	1.000	65	2.664	1.000
23	0.002	1.000	37	0.002	992.080	66	2.160	1.000	66	3.117	1.000
24	2.191	1.000	44	0.002	281.540	68	13.129	1.000	68	15.403	1.000
27	1.022	1.000	60	0.040	1.000	71	6.121	1.000	91	0.002	2985.120
29	0.731	1.000	66	0.911	1.000	87	0.954	1.000	95	0.002	15.000
31	0.002	117.420	68	9.977	1.000	91	0.002	3675.520	110	3.451	1.000
33	2.567	1.000	71	3.388	1.000	95	0.002	1.000	125	2.805	1.000
37	0.002	264.788	87	0.002	1.000	110	5.709	1.000	139	6.230	1.000
44	0.002	1665.900	91	0.002	8458.880	125	3.564	1.000	168	0.002	253.072
45	0.040	1.000	95	0.002	82.568	137	0.002	15.000	172	1.037	1.000
66	1.122	1.000	110	3.515	1.000	139	2.533	1.000
68	11.877	1.000	125	2.875	1.000	157	3.114	1.000
71	3.647	1.000	137	0.002	15.655	168	0.002	815.853
87	1.229	1.000	139	0.332	1.000	172	2.956	1.000
91	0.002	306.800	157	2.047	1.000
95	0.119	1.000	168	0.002	132.660
110	2.735	1.000	172	0.807	1.000
125	1.485	1.000
157	3.796	1.000
168	0.002	91.153
172	1.085	1.000

TABLE 6

Individual values of circulating infliximab (IFX)
and immunogenicity (antibodies). Infusion number 8 is shown.
Infusion number 8

Patient	IFX (μg/ml)	Antibodies (AU/ml)

19	0.002	21204.280
27	0.298	1.000
29	2.057	1.000
33	14.348	1.000
44	0.002	15.000
54	0.298	1.000
60	5.181	1.000
65	6.815	1.000
66	1.861	1.000
68	13.291	1.000
95	0.426	1.000
110	1.780	1.000
139	3.466	1.000
168	0.040	1.000

After the analysis of the samples the following distribution was observed for infliximab (Table 7).

TABLE 7

Distribution of patients according to different combinations
of infliximab bioavailability and immunogenicity.

	Bioavailability/Immunogenicity	Patients*	Samples

positive/negative	68	390
negative/positive	35	142
negative/negative	51	80
positive/positive	0	0

*Due to multiple number of samples per patient, patients can be present in more than one group.

FIG. 1 shows the average bioavailability and immunogenicity profiles over one year of treatment of all the patients that do not respond to the treatment with infliximab. In this example it is shown that ΔDAS28 is lower than 1.2; therefore, the patients are classified as non-responders to the treatment with infliximab. Concomitantly with the presence of antibodies against infliximab, the concentration of free infliximab drops below the cut-off value.
FIG. 2 shows the average bioavailability and immunogenicity profiles over one year of treatment of the patients that respond to the treatment with infliximab. In this example it is shown that ΔDAS28 is higher than 1.2; therefore, the patient is classified as responder to infliximab treatment. Concomitantly with the presence of antibodies against infliximab, the concentration of free infliximab drops below the cut-off value.
Bioavailability and Immunogenicity Correlation:
Bioavailability and immunogenicity of infliximab strongly correlate (p<0.01). Statistical correlation analysis was performed using Kendall's Tau-b and Sperman tests. Correlation results are shown in Table 8.

TABLE 8

Correlation between bioavailability and immunogenicity of infliximab.

Kendall's Tau-b test

Sperman test

	Correlation		Correlation
Parameter	coefficient	p-value	coefficient	p-value

Bioavailability	−0.491	1.00E−06	−0.606	1.00E−06
Immunogenicity

Clinical Correlations:
The correlations between bioavailability, immunogenicity and the disease activity based on the DAS28 values were analyzed. Clinical responses strongly correlate with the levels of free infliximab (drug bioavailability) and the formation of anti-infliximab antibodies (drug immunogenicity) (Table 9). In addition, infliximab concentration and antibodies against the drug strongly correlate (p<−0.001). The concentration of infliximab inversely correlates with DAS28 (p<−0.001), whereas the concentration of anti-infliximab antibodies directly correlates with DAS28 (p<0.001).

TABLE 9

Correlation between the infliximab bioavailability, anti-infliximab
antibodies (immunogenicity) and DAS28.

	Concentration
Concentration of	of anti-infliximab
infliximab	antibodies
(μg/ml)	(AU/ml)
(Bioavailability)	(Immunogenicity)	DAS28

Concentration of	—	p < −0.001	p < −0.001
infliximab (μg/ml)
Concentration of	p < −0.001	—	p < 0.001
anti-infliximab
antibodies (AU/ml)
DAS28	p < −0.001	p < 0.001	—

A positive p value indicates a direct correlation.
A negative p value indicates an inverse correlation.
p values <0.05 or <−0.05 are statistically significant.

Determination of Diagnostic Cut-Offs:
According to the standard protocol to determine immunogenicity, there is never a positive titer of anti-infliximab antibodies above 1.5 μg/ml of free infliximab. Therefore, diagnostic cut-off was determined by measuring the anti-infliximab antibodies concentration with the acid dissociation protocol in those samples with concentrations of free infliximab below 1.5 μg/ml. 45 patients (183 samples) fulfilling this criteria were analysed. 51% of the patients (33% of the samples) showed a positive immunogenicity titer (Table 10).

TABLE 10

Detection of antibodies anti-infliximab using the acid dissociation
protocol in samples with free infliximab below 1.5 μg/ml.

		Positive samples after acid
Samples #	Patients #	dissociation protocol/patients

183	45	60 (33%)/23

It was further studied if there is a relationship between the level of free infliximab below 1.5 μg/ml and the presence of antibodies anti-infliximab above 15 AU/ml (equivalent to 150 ng/ml of antibodies) (limit of detection) with DAS28 (Table 11) in the whole cohort of patients.

TABLE 11

Disease activity as a function of bioavailability and
immunogenicity cut-offs.

Grouping	Average DAS28	SD	p-value

Infliximab >1.5 μg/ml AND	3.35	0.97	<0.01
antibodies anti-infliximab <15 AU/ml
Infliximab <1.5 μg/ml AND	3.89	1.41
antibodies anti-infliximab >15 AU/ml

SD, standard deviation.
p value <0.05 is statistically significant.

Inventors studied the same relationship between responder and non-responder patients (Table 12).

TABLE 12

Correlation of infliximab bioavailability and immunogenicity
cut-offs with the clinical response.

		Average
Population	Cut-offs combination	DAS28 (N)	SD	p-value

With	Free infliximab >1.5 μg/ml	3.30 (107)	0.98	0.546
clinical	AND antibodies
	anti-infliximab <15 AU/ml
response	Free infliximab <1.5 μg/ml	3.51 (41)	1.28
	AND antibodies
	anti-infliximab >15 AU/ml
With no	Free infliximab >1.5 μg/ml	3.52 (33)	0.97	<0.01
clinical	AND antibodies
	anti-infliximab <15 AU/ml
response	Free infliximab <1.5 μg/ml	4.25 (42)	1.46
	AND antibodies
	anti-infliximab >15 AU/ml

SD, standard deviation.
Different combinations of cut-offs are considered.
p values <0.05 are statistically significant.

It is demonstrated that patients with an infliximab bioavailability lower than 1.5 μg/ml and antibodies anti-infliximab higher than 15 AU/ml show a higher DAS28 than those patients with infliximab bioavailability higher than 1.5 μg/ml.
Therefore, if a patient shows a combination of free infliximab lower than (<) 1.5 μg/ml AND antibodies anti-infliximab higher than (>) 15 AU/ml, there is a higher probability that the individual is a non-responder to the infliximab treatment, showing a high activity of the disease (see EULAR guidelines on Table 1).
FIG. 3 shows how the bioavailability of infliximab (circulating concentration of infliximab) and immunogenicity of infliximab (anti-infliximab antibodies) variables are associated to the DAS28 index, and therefore can be used to classify patients and predict the status of a patient according to the EULAR DAS guidelines.
Accordingly, a patient showing a combination of free infliximab equal to or higher than (≧) 1.5 μg/ml AND antibodies anti-infliximab equal to or lower than (≦) 15 AU/ml has a higher probability of being a responder patient to the infliximab treatment; however, patients showing bioavailability lower than 1.5 μg/ml and antibodies anti-infliximab higher than 15 AU/ml have a higher probability of being non-responder patients to the infliximab treatment.
Infliximab Decision Algorithm:
It is demonstrated that the clinical response to infliximab closely follows the drug levels and the presence of antibodies directed against the drug.
It is thus demonstrated that if a patient has a bioavailability value below 1.5 μg/ml AND an immunogenicity value above 15 AU/ml, this will correlate with no clinical response to the treatment, therefore an increased DAS28 value (moderate or high disease activity) compared to those with bioavailability values above 1.5 μg/ml (p<0.001).
None of the analysed patients showed anti-infliximab antibodies if the concentration of free infliximab was above 1.5 μg/ml.
The following decision algorithm can be constructed from the data:


1. Analysis	Free infliximab bioavailability determination AND
	anti-infliximab antibodies analysis

2. Result	Free infliximab	Free infliximab
	concentration ≧1.5 μg/ml	concentration <1.5 μg/ml
	AND anti-infliximab	AND anti-infliximab
	antibodies ≦15 AU/ml	antibodies >15 AU/ml
3. Patient	Responder	Non-responder
classification
4. Action	None. Adequate treatment	Inefficient treatment.
		Follow up required.
		The treatment should be
		considered.

Example 2

Correlation of Bioavailability and Immunogenicity of Adalimumab with the Clinical Response of Patients Suffering from Rheumatoid Arthritis

Subjects:
Rheumatoid arthritis patients, 49, fulfilling the 1987 ACR criteria and about to start treatment with adalimumab, were enrolled consecutively. 171 serum samples were analysed.
Treatment:
Patients received doses of 40 mg of adalimumab (Humira®), subcutaneously, every two weeks.
Evaluation of the Patient Clinical Response:
DAS28 was used to evaluate the clinical response of the patient according scores in Table 1 (Example 1).
Bioavailability and Immunogenicity Correlation:
Bioavailability and immunogenicity of adalimumab strongly correlate (p<0.05). Statistical correlation analysis was performed using Kendall's Tau-b and Sperman tests. Correlation results are shown in Table 13.

TABLE 13

Correlation between bioavailability and immunogenicity of adalimumab.

Kendall's Tau-b test

Sperman test

	Correlation		Correlation
Parameter	coefficient	p-value	coefficient	p-value

Bioavailability	−0.363	1.00E−06	−0.444	1.00E−06
Immunogenicity

Clinical Correlations:
The correlation between bioavailability, immunogenicity and the disease activity based on the DAS28 values was analyzed. Clinical response strongly correlates with the level of free adalimumab (drug bioavailability) and antibodies against adalimumab (immunogenicity) (Table 14).

TABLE 14

Correlation between the adalimumab bioavailability, anti-adalimumab
antibodies (immunogenicity) and DAS28.

	Concentration
	of anti-
Concentration of	adalimumab
adalimumab	antibodies
(μg/ml)	(AU/ml)
(Bioavailability)	(Immunogenicity)	DAS28

Concentration of	—	−0.001 (171)	−0.001 (102)
adalimumab (μg/ml)
Concentration of	−0.001 (171)	—	0.09 (102)
anti-adalimumab
antibodies (AU/ml)
DAS28	−0.001 (102)	0.09 (102)	—

A positive p value indicates a direct correlation.
A negative p value indicates an inverse correlation.
p values <0.05 or <−0.05 are statistically significant.
*p value of 0.06 is considered statistically significant. The value is very close to the significance criteria of p < 0.05, and therefore clinically relevant.

Determination of Diagnostic Cut-Offs:
According to the standard protocol to determine immunogenicity, there is never a positive titer of anti-adalimumab antibodies above 0.8 μg/ml of free adalimumab. Therefore, diagnostic cut-off was determined by measuring the anti-adalimumab antibodies concentration with the acid dissociation protocol in those samples with concentrations of free adalimumab below 0.8 μg/ml. 54 samples fulfilling this criteria were analysed. 22% of the patients with free adalimumab below 0.8 μg/ml showed a positive immunogenicity titer, and 77% of the patients with free adalimumab below the limit of detection (2 ng/ml) showed a positive immunogenicity titer (Table 15).

TABLE 15

Detection of antibodies anti-adalimumab using the acid dissociation
protocol in samples with free adalimumab below 0.8 ug/ml and
no antibodies against adalimumab.

	Free adalimumab	Free adalimumab
	<2 ng/ml, no antibodies	<0.8 μg/ml, no antibodies

Samples #	Patients #	Samples #	Patients #
28	18	26	13

Positive after acid	5 (18%)	4 (22%)	10 (38%)	10 (77%)
dissociation

It was studied if there is a relationship between the level of free adalimumab below 0.8 μg/ml and the presence of antibodies anti-adalimumab above 8 AU/ml (equivalent to 32 ng/ml of antibodies) (limit of detection) with DAS28 (Table 16) in the whole cohort of patients.

TABLE 16

Disease activity as a function of bioavailability and immunogenicity
cut-offs. p value <0.05 is statistically significant.

	Average
Grouping	DAS28	p-value

Adalimumab >0.8 μg/ml AND antibodies anti-	2.56 (53)	0.037
adalimumab <8 AU/ml
Adalimumab <0.8 μg/ml AND antibodies anti-	3.27 (4)
adalimumab >8 AU/ml

It is demonstrated that patients with an adalimumab bioavailability lower than 0.8 μg/ml and antibodies anti-adalimumab higher than 8 AU/ml (equivalent to 32 ng/ml of antibodies) show a higher DAS28 value compared to those with an adalimumab bioavailability higher than 0.8 μg/ml and antibodies anti-adalimumab lower than 8 AU/ml. This DAS28 difference is statistically significant.
Therefore, if a patient shows a combination of free adalimumab lower than (<) 0.8 μg/ml AND antibodies anti-adalimumab higher than (>) 8 AU/ml, there is a higher probability that the individual is a non-responder to the adalimumab treatment, showing a high activity of the disease (see EULAR guidelines on Table 1 and Table 16).
Accordingly, a patient showing a combination of free adalimumab equal to or higher than (≧) 0.8 μg/ml AND antibodies anti-adalimumab equal to or lower than (≦) 8 AU/ml has a higher probability of being a responder patient to the adalimumab treatment.
Adalimumab Decision Algorithm:
It is demonstrated that the clinical response to adalimumab closely follows the drug levels and the presence of antibodies directed against the drug.
It is demonstrated that if a patient has a bioavailability value below 0.8 μg/ml AND an immunogenicity value above 8 AU/ml (equivalent to 32 ng/ml of antibodies), this will correlate with a higher probability of showing no clinical response to the treatment, therefore an increased DAS28 value (moderate or high disease activity) compared to those with bioavailability values above 0.8 μg/ml (p<0.001).
None of the analysed patients showed anti-adalimumab antibodies if the concentration of free adalimumab was above 0.8 μg/ml.
The following decision algorithm can be constructed from the data:


1. Analysis	Free adalimumab bioavailability determination AND
	anti-adalimumab antibodies analysis

2. Result	Free adalimumab	Free adalimumab
	concentration ≧0.8 μg/ml	concentration <0.8 μg/ml
	AND anti-adalimumab	AND anti-adalimumab
	antibodies ≦8 AU/ml	antibodies >8 AU/ml
3. Patient	Responder	Non-responder
classification
4. Action	None. Adequate treatment	Inefficient treatment.
		Follow up required.
		The treatment should
		be considered.

Example 3

Correlation of Bioavailability of Infliximab with the Clinical Response of Patients Suffering from Rheumatoid Arthritis

Experiments were performed as described in Example 1 except that the anti-infliximab antibody levels were not analized. Thus, patients were classified according to the infliximab therapeutical cut-off.
Infliximab trough levels are significantly higher (2.73 μg/ml) in patients suffering from rheumatoid arthritis that show a good or moderate clinical response (responders) to the treatment (p=1E-09) compared to non-responders (0.002 μg/ml) after one year of treatment (Table 17).

TABLE 17

Comparison between trough infliximab levels
according to response criteria.

Patient
classification	Median trough infliximab (μg/ml)	N	p

Responder	2.73	71	1E−09
Non-responder	0.002	54

To calculate the frequency of responders and non-responders rheumatoid arthritis patients after one year of treatment, we performed significance tests by Chi-squared analysis (Table 18). The number of patients that are classified as responders is significantly higher than non-responders when trough infliximab concentration is ≧1.5 μg/ml (p=3.55E-07). On the other hand, the number of patients that are classified as responders is significantly lower than non-responders when trough infliximab concentration is <1.5 μg/ml (p=0.028).

TABLE 18

Comparison of the frequency of responder and non-responder rheumatoid
arthritis patients depending on the infliximab cut-off.

	Patient
Infliximab concentration	classification	N	p (χ²)

≧1.5 μg/ml	Responder	43	3.5E−07
	Non-responder	7
<1.5 μg/ml	Responder	28	0.028
	Non-responder	47

When trough infliximab concentration is ≧1.5 μg/ml, the median drug level of responder patients is 3.64 μg/ml, while is 2.68 μg/ml in the non-responder population (p=0.142). However, when trough infliximab concentration is <1.5 the median drug level of responder patients is significantly higher (0.06 μg/ml) than in the non-responder population (0.002 μg/ml) (p=4.23E-03) (Table 19).

TABLE 19

Median infliximab concentration for responder and non-responder
populations depending on the infliximab cut-off.

	Patient			p (Kruskal-
Infliximab concentration	classification	N	Median	Wallis)

≧1.5 μg/ml	Responder	43	3.6472	0.142
	Non-responder	7	2.688
<1.5 μg/ml	Responder	28	0.0607	4.2E−03
	Non-responder	47	0.002

Therefore, if a patient has an infliximab trough level <1.5 μg/ml it is more likely to have lost drug efficacy and be classified as a non-responder, therefore necessitating of a treatment regime revision. On the other hand, if a patient has an infliximab trough level ≧1.5 μg/ml it is more likely that the patient corresponds to a responder, since the patient is exposed to effective drug levels.

Example 4

Correlation of Bioavailability of Adalimumab with the Clinical Response of Patients Suffering from Rheumatoid Arthritis

Experiments were performed as described in Example 2 except that the anti-adalimumab antibody levels were not analized. Thus, patients were classified according to the adalimumab therapeutical cut-off.
Adalimumab trough levels are significantly higher (12.25 μg/ml) in patients suffering from rheumatoid arthritis that show a good or moderate clinical response (responders) to the treatment (p=0.0005) compared to non-responders (4.15 μg/ml) after two years of treatment (Table 20).

TABLE 20

Comparison between trough adalimumab levels
according to response criteria.

Patient	Median trough adalimumab
classification	(μg/ml)	N	p

Responder	12.25	16	0.0005
Non-responder	4.15	45

To calculate the frequency of responder and non-responder rheumatoid arthritis patients after two years of treatment, we performed significance tests by Chi-squared analysis (Table 21). All patients with an adalimumab trough level <0.8 μg/ml are non-responders. No patients were classified as responders with adalimumab trough levels <0.8 μg/ml.

TABLE 21

Comparison of the frequency of responder and non-responder rheumatoid
arthritis patients depending on the adalimumab cut-off.

Adalimumab concentration	Patient	N	p (χ²)

≧0.8 μg/ml	Responder	16	0.093
	Non-responder	27
<0.8 μg/ml	Responder	0	p < 0.05
	Non-responder	16

When trough adalimumab concentration is ≧0.8 μg/ml, the median drug level of responder rheumatoid arthritis patients is 12.25 μg/ml, while is 6.73 μg/ml in the non-responder population (Table 22).

TABLE 22

Median adalimumab concentration of responder and non-responder
populations depending on the adalimumab cut-off.

Adalimumab	Patient			p (Kruskal-
concentration	classification	N	Median	Wallis)

≧0.8 μg/ml	Responder	16	12.25	0.06
	Non-responder	27	6.73
<0.8 μg/ml	Responder		0	0	p < 0.05
	Non-responder	16	0.00008

In conclusion, if a patient has an adalimumab trough level <0.8 μg/ml it is more likely to have lost drug efficacy and be classified as a non-responder, therefore necessitating of a treatment regime revision. On the other hand, if a patient has an adalimumab trough level ≧0.8 μg/ml there is an increased probability that the patient could be responding to the therapy.

Claims

1. A method for classifying a patient suffering from rheumatoid arthritis as a responder or as a non-responder patient to a treatment, said treatment comprising the administration to said patient of a biological drug selected from the group consisting of infliximab and adalimumab that is periodically administered by repetitive administrations, and wherein said patient has received at least one dose from said biological drug, said method comprising the steps of:

a) determining the concentration of the circulating biological drug in a sample from said patient at a time t1 wherein said t1 corresponds to a time point within the period of time between two successive administrations of said biological drug;

b) determining the concentration of antibodies against said biological drug in a sample from said patient at a time t1; and

c) comparing the concentration of the circulating biological drug at said t1 with a Reference Value 1 (RV1) and the concentration of antibodies against said biological drug at said time t1 with a Reference Value 2 (RV2),

wherein

the sample is selected from a sample of blood, a sample of plasma and a sample of serum;

RV1 is a therapeutic efficiency cut-off value of the concentration of the circulating biological drug; and

RV2 is the cut-off value of the concentration of said antibody against the biological drug as determined in a group of treatment-naïve individuals by the same assay as that used for determining the concentration of the antibody against the biological drug in step b), and

wherein if the concentration of the circulating biological drug is lower than RV1 and the concentration of antibodies against said biological drug is higher than RV2, then said patient is classified as a non-responder patient to said treatment, and

wherein if the concentration of the circulating biological drug is equal to, or higher than RV1 and the concentration of antibodies against said biological drug is equal to, or lower than, RV2, then said patient is classified as a responder patient to said treatment, and

wherein if the biological drug is infliximab, then RV1 is 1.5 μg/ml; and

wherein if the biological drug is adalimumab, then RV1 is 0.8 μg/ml.

2. The method according to claim 1, wherein said t1 is a time point within two weeks of the administration of the biological drug.

3. The method according to claim 1, wherein the concentration of the circulating biological drug is determined by an immunoassay.

4. The method according to claim 1, wherein the concentration of antibodies against said biological drug is determined by an immunoassay.

5. The method according to claim 3, wherein the immunoassay is an ELISA.

6. The method according to claim 4, wherein the immunoassay is an ELISA.

7. The method according to claim 1, wherein said t1 is a time point within one week of the administration of the biological drug.

8. The method according to claim 1, wherein if the biological drug is infliximab, then RV2 is 150 ng/ml, and wherein if the biological drug is adalimumab, then RV2 is 32 ng/ml.

9. A method for treating a patient suffering from rheumatoid arthritis, comprising:

a) administering to said patient a biological drug at a time, ti, wherein the biological drug is selected from the group consisting of infliximab and adalimumab;

b) determining the concentration of the circulating biological drug in a sample from said patient at a time, ti, wherein t1 is a time point after ti;

c) determining the concentration of antibodies against said biological drug in a sample from said patient at t1; and

d) comparing the concentration of the circulating biological drug at ti with a Reference Value 1 (RV1) and the concentration of antibodies against said biological drug at t1 with a Reference Value 2 (RV2),

wherein:

RV1 is a therapeutic efficiency cut-off value of the concentration of the circulating biological drug;

RV2 is the cut-off value of the concentration of said antibody against the biological drug as determined in a group of treatment-naïve individuals by the same assay as that used for determining the concentration of the antibody against the biological drug in step c);

wherein if the concentration of the circulating biological drug is equal to, or higher than RV1 and the concentration of antibodies against said biological drug is equal to, or lower than, RV2, then classifying the patient as a responder and repeating step a); and

wherein if the concentration of the circulating biological drug is equal to, or higher than RV1 and the concentration of antibodies against said biological drug is equal to, or lower than, RV2, then classifying the patient as a non-responder and revising treatment.

10. The method according to claim 9, wherein t1 is a time point within two weeks of ti.

11. The method according to claim 9, wherein t1 is a time point within one week of ti.

12. The method according to claim 9, wherein the concentration of the circulating biological drug is determined by an immunoassay.

13. The method according to claim 12, wherein the immunoassay is an ELISA.

14. The method according to claim 9, wherein the concentration of antibodies against said biological drug is determined by an immunoassay.

15. The method according to claim 14, wherein the immunoassay is an ELISA.

16. The method according to claim 1, wherein if the biological drug is infliximab, then RV1 is 1.5 μg/ml, and wherein if the biological drug is adalimumab, then RV1 is 0.8 μg/ml.

17. The method according to claim 16, wherein if the biological drug is infliximab, then RV2 is 150 ng/ml, and wherein if the biological drug is adalimumab, then RV2 is 32 ng/ml.