CIRCULATING FGFBP-1 (FIBROBLAST GROWTH FACTOR-BINDING PRO-TEIN 1) IN THE ASSESSMENT OF ATRIAL FIBRILLATION AND FOR THE PREDICTION OF STROKE

Abstract

The present invention relates to a method for assessing atrial fibrillation in a subject, said method comprising the steps of determining the amount of FGFBP-1 in a sample from the subject, and comparing the amount of FGFBP-1 to a reference amount, whereby atrial fibrillation is to be assessed. Moreover, the present invention relates to methods for the prediction of stroke based on the amount of FGFBP-1.

Claims

1. A method for assessing atrial fibrillation in a subject, comprising the steps of a) determining, in at least one sample from the subject, the amount of the biomarker FGFBP-1 (Fibroblast growth factor-binding protein 1) and, optionally, the amount of at least one further biomarker selected from the group consisting of a natriuretic peptide, ESM-1 (Endocan), Ang2 (Angiopoietin 2) and IGFBP7 (Insulin-like growth factor-binding protein 7), and b) comparing the amount of the biomarker FGFBP-1 to a reference amount for FGFBP-1 and, optionally, comparing the amount of the at least one further biomarker to a reference amount for said at least one further biomarker, whereby atrial fibrillation is to be assessed.

2. The method of claim 1, wherein the sample is selected from the group consisting of a blood, serum or plasma sample.

3. The method of claim 1, wherein the subject is human.

4. The method according to claim 1, wherein the assessment of atrial fibrillation is the diagnosis of atrial fibrillation.

5. The method of claim 4, wherein the diagnosis of atrial fibrillation is the diagnosis of persistent atrial fibrillation.

6. The method of claim 4, wherein an amount of FGFBP-1 and, optionally, an amount of the at least one further biomarker above the reference amount is indicative for a subject suffering from atrial fibrillation and/or wherein an amount of FGFBP-1 and, optionally, an amount of the at least one further biomarker below (or equal to) the reference amount is indicative for a subject not suffering from atrial fibrillation.

7. The method of claim 1, wherein the assessment of atrial fibrillation is the prediction of the risk of an adverse event associated with atrial fibrillation.

8. The method of claim 7, wherein an amount of FGFBP-1 and, optionally, an amount of the at least one further biomarker above the reference amount is indicative for a subject who is at risk of suffering from an adverse event associated with atrial fibrillation and/or wherein an amount of FGFBP-1 and, optionally, an amount of the at least one further biomarker below (or equal to) the reference amount is indicative for a subject who is not at risk of suffering from an adverse event associated with atrial fibrillation.

9. A method for predicting the risk of stroke in a subject, comprising the steps of (a) determining, in at least one sample from the subject, the amount of the biomarker FGFBP-1 (Fibroblast growth factor-binding protein 1) and, optionally, the amount of at least one further biomarker selected from the group consisting of a natriuretic peptide, ESM-1 (Endocan), Ang2 (Angiopoietin 2) and IGFBP7 (Insulin-like growth factor-binding protein 7), and (b) assessing the clinical stroke risk score for said subject, and (c) predicting the risk of stroke based on the results of steps a) and b).

10. A method for improving the prediction accuracy of a clinical stroke risk score for a subject, comprising the steps of a) determining, in at least one sample from the subject, the amount of the biomarker FGFBP-1 (Fibroblast growth factor-binding protein 1) and, optionally, the amount of at least one further biomarker selected from the group consisting of a natriuretic peptide, ESM-1 (Endocan), Ang2 (Angiopoietin 2) and IGFBP7 (Insulin-like growth factor-binding protein 7), wherein the subject has a known clinical stroke risk score, and b) combining a value for the amount of FGFBP-1 and/or the amount of one or more biomarkers comprising of a natriuretic peptide, ESM-1, ANGT2, IGFBP7 with the clinical stroke risk score, whereby the prediction accuracy of said clinical stroke risk score is improved.

11. A method of aiding in the assessment of atrial fibrillation, said method comprising the steps of: a) providing at least one sample from a subject, b) determining, in the at least one sample provided in step a), the amount of the biomarker FGFBP-1 (Fibroblast growth factor-binding protein 1) and, optionally, the amount of at least one further biomarker selected from the group consisting of a natriuretic peptide, ESM-1 (Endocan), Ang2 and IGFBP7 (Insulin-like growth factor-binding protein 7), and c) providing information on the determined amount of the biomarker FGFBP-1 and optionally on the determined amount of the at least one further biomarker to a physician, thereby aiding in the assessment of atrial fibrillation.

12. A method for aiding in the assessment of atrial fibrillation, comprising: a) providing an assay for the biomarker FGFBP-1 and, optionally, at least one further assay for a further biomarker selected from the group consisting of a natriuretic peptide, ESM-1 (Endocan), Ang2 and IGFBP7 (Insulin-like growth factor-binding protein 7), and b) providing instructions for use of assay results obtained or obtainable by said assay(s) in the assessment of atrial fibrillation.

13. A computer-implemented method for assessing atrial fibrillation, comprising a) receiving, at a processing unit, a value for the amount of FGFBP-1, and, optionally at least one further value for the amount of at least one further biomarker selected from the group consisting of a natriuretic peptide, ESM-1 (Endocan), Ang2 and IGFBP7 (Insulin-like growth factor-binding protein 7), wherein said amount of FGFBP-1 and, optionally, the amount of the at least one further biomarker have been determined in a sample from a subject, b) comparing, by said processing unit, the value or values received in step (a) to a reference or to references, and c) assessing atrial fibrillation based in the comparison step b).

14. A kit comprising an antibody or antigen-binding fragment thereof which specifically binds to FGFBP-1 and at least one further antibody or antigen-binding fragment thereof selected from the group consisting of an antibody or antigen-binding fragment thereof which specifically binds to a natriuretic peptide, an antibody or antigen-binding fragment thereof which specifically binds to ESM-1 and an antibody or antigen-binding fragment thereof which specifically binds to IGFBP7.

15. In vitro use of i) the biomarker FGFBP-1 and optionally of at least one further biomarker selected from the group consisting of a natriuretic peptide, ESM-1 (Endocan), Ang2 and IGFBP7 (Insulin-like growth factor-binding protein 7), and/or ii) at least one agent that specifically binds to FGFBP-1, and, optionally, at least one further agent selected from the group consisting of an agent which specifically binds to a natriuretic peptide, an agent which specifically binds to ESM-1, an agent which specifically binds to Ang2 and an agent which specifically binds to IGFBP7, for a) assessing atrial fibrillation, b) predicting the risk of stroke in a subject, and for c) improving the prediction accuracy of a clinical stroke risk score.

16. The method of claim 7, wherein the adverse event associated with atrial fibrillation is stroke.

Description

[0312] The Figures Show:

[0313] FIGS. 1A&1B: Measurement of FGFBP1 in Mapping Study: Exploratory Afib panel: Patients with a history of atrial fibrillation undergoing open chest surgery and epicardial mapping of persistent AF or SR (Mapping Study). Circulating FGFBP1 levels were assessed. Boxplot (FIG. 1A) shows the FGFBP-1 distribution in patients with SR vs patient with persAF. ROC (FIG. 1B) shows the diagnostic ability of FGFBP-1 to discriminate between patients with SR vs patient with persAF.

[0314] FIG. 2: Prediction the risk of stroke FGFBP1 (Beat AF study): The FIG. 2 shows, that elevated titers of FGFBP1 associate to increased risk of stroke. FGFBP1 improved the C-Index of several clinical risk scores. FIG. 2 shows the stroke-free survival in the two groups defined by having a FGFBP-1 value <=35 vs >35 NPX.

EXAMPLES

[0315] The invention will be merely illustrated by the following Examples. The said Examples shall, whatsoever, not be construed in a manner limiting the scope of the invention.

EXAMPLES

Example 1: Assessment of AF with Circulating FGFBP-1

[0316] The MAPPING study related to patients undergoing open chest surgery. Samples were obtained before anesthesia and surgery. Patients were electrophysiologically characterized using high-density epicardial mapping with multi-electrode arrays (high density mapping).

[0317] Circulating FGFBP-1 levels have been determined in 16 patients with persistent atrial fibrillation and 30 controls, matched to best possible (on age, gender, comorbidities). FGFBP-1 was determined in samples of the MAPPING study.

[0318] Measurements were performed in 30 patients with sinus rhythm (SR) and in 16 persistent atrial fibrillation (persAF).

[0319] FIG. 1 shows that FGFBP-1 is significantly elevated in patients with persAF in comparison to patients in SR (AUC 0.70). Therefor FGFBP-1 could be used for aid in diagnosis of persAF. Elevated FGFBP-1 values would indicate a higher probability of persAF.

Example 2: Prediction of Stroke

[0320] The ability of circulating FGFBP-1 to predict the risk for the occurrence of stroke was assessed in a prospective, multicentric registry of patients with documented atrial fibrillation (Conen D., Forum Med Suisse 2012; 12:860-862). FGFBP-1 was measured using a stratified case cohort design as described in Borgan (2000).

[0321] For each of the 70 patients which experienced a stroke during follow up (“events”), 1 matched control was selected. Controls were matched based on the demographic and clinical information of age, sex, history of hypertension, atrial fibrillation type and history of heart failure (CHF history).

[0322] FGFBP-1 results were available for 67 patients with an event and 66 patients without an event. FGFBP-1 was measured using the Olink platform therefor no absolute concentration values are available and can be reported. Results will be reported on an arbitrary signal scale (NPX).

[0323] In order to quantify the univariate prognostic value of FGFBP-1 proportional hazard models were used with the outcome stroke. The univariate prognostic performance of FGFBP-1 was assessed by two different incorporations of the prognostic information given by FGFBP-1.

[0324] The first proportional hazard model included FGFBP-1 binarized at the median (35 NPX) and therefore comparing the risk of patients with FGFBP-1 below or equal to the median versus patient with FGFBP-1 above the median.

[0325] The second proportional hazard model included the original FGFBP-1 levels but transformed to a log 2 scale. The log 2 transformation was performed in order to enable a better model calibration.

[0326] Because the estimates from a naïve proportional hazard model on the case control cohort would be biased (due to the altered proportion of cases to controls) a weighted proportional hazard model was used. Weights are based on the inverse probability for each patient to be selected for the case control cohort as described in Mark (2006).

[0327] In order to get estimates for the absolute survival rates in the two groups based on the dichotomized baseline FGFBP-1 measurement (<=35 NPX vs >35 NPX) a weighted version of the Kaplan-Meier plot was created as described in Mark (2006). In order to assess if the prognostic value of FGFBP-1 is independent from known clinical and demographic risk factors a weighted proportional cox model including in addition the variables age, sex, CHF history, history of hypertension, Stroke/TIA/Thromboembolism history, vascular disease history and diabetes history was calculated.

[0328] In order to assess the ability of FGFBP-1 to improve existing risk scores for the prognosis of stroke the CHADS.sub.2 the CHA.sub.2DS.sub.2-VASc and the ABC score were extended by FGFBP1 (log 2 transformed). Extension was done by creating a portioned hazard model including FGFBP-1 and the respective risk score as independent variables.

[0329] The c-indices of the CHADS.sub.2, the CHA.sub.2DS.sub.2-VASc and ABC score were compared to the c-indices of these extended models. For the calculation of the c-index in the case-cohort setting a weighted version of the c-index was used as proposed in Ganna (2011).

[0330] Results

[0331] Table 1 shows the results of the two univariate weighted proportional hazard models including the binarized or the log 2 transformed FGFBP-1. The association between the risk for experiencing a stroke with the baseline value of FGFBP-1 is highly significant in both models.

[0332] The hazard ratio for the binarized FGFBP-1 implies a 1.38-fold higher risk for a stroke in the patient group with baseline FGFBP-1 >=35 NPX versus the patient group with baseline FGFBP-1<35 NPX. This is also visible in FIG. 2 showing the Kaplan-Meier curve which depicts the probability over time to survive until the occurrence of a stroke event.

[0333] However, the p-value is above 0.05 which might indicate that binarization is sub-optimal in this case.

[0334] The results of the proportional hazard model including FGFBP-1 as log 2 transformed linear risk predictor suggest the log 2 transformed values FGFBP-1 are proportional to the risk for experiencing a stroke. The hazard ratio of 2.67 can be interpreted in a way that a 2-fold increase of FGFBP-1 is associated with 2.67 increase of risk for a stroke.

TABLE-US-00001 TABLE 1 Results result of the univariate weighted proportional hazard model including the binarized and log2 transformed FGFBP-1. Hazard Ratio (HR) 95%-CI HR P-Value FGFBP-1 log2 2.6741 1.8756-3.8127 <0.0001 Baseline 1.3841 0.6796-2.8188  0.3704 FGFBP-1 > = 35 NPX vs FGFBP-1 < 35 NPX

[0335] Table 2 shows the results of a proportional hazard model including FGFBP-1 (log 2 transformed) in the combination with clinical and demographic variables. It clearly shows that the prognostic effect of FGFBP-1 stays stable if adjusting for the prognostic effect of relevant clinical and demographic variables.

TABLE-US-00002 TABLE 2 Multivariate proportional hazard model including FGFBP-1 and relevant clinical and demographic variables. Hazard Ratio (HR) 95%-CI HR P-Value History hypertension 1.2679 0.5885-2.7315 0.5445 Age 1.0352 0.9893-1.0832 0.1352 History 2.1467 0.8808-5.2322 0.0928 Stroke/TIA/embolism Sex = male 0.7785 0.3697-1.6395 0.51 History CHF 0.6947 0.2837-1.7009 0.4252 History vascular disease 1.2158 0.4779-3.0931 0.6816 FGFBP-1 (log2 2.5743 1.7861-3.7105 <0.0001 transformed)

[0336] Table 3 shows the results of the weighted proportional hazard model combining the CHADS.sub.2 score with FGFBP-1 (log 2 transformed). Also in this model FGFBP-1 can add prognostic information to the CHADS.sub.2 score.

TABLE-US-00003 TABLE 3 Weighted proportional hazard model combining the CHADS.sub.2 score with FGFBP-1 (log2 transformed) Hazard Ratio (HR) 95%-CI HR P-Value CHADS.sub.2 score 1.3925 1.0913-1.777  0.0078 FGFBP-1 (log2 2.627 1.8435-3.7434 <0.0001 transformed)

[0337] Table 4 shows the results of the weighted proportional hazard model combining the CHA.sub.2DS.sub.2-VASc score with FGFBP-1 (log 2 transformed). Also in this model FGFBP-1 can add prognostic information to the CHA.sub.2DS.sub.2-VASc score.

TABLE-US-00004 TABLE 4 Weighted proportional hazard model combining the CHA.sub.2DS.sub.2-VASc score with FGFBP-1 (log2 transformed) Hazard Ratio (HR) 95%-CI HR P-Value CHA.sub.2DS.sub.2-VASc 1.3779 1.0779-1.7612 0.0105 score FGFBP-1 (log2 2.5013 1.6738-3.7379 <0.0001 transformed)

[0338] Table 5 shows the results of the weighted proportional hazard model combining the ABC score with FGFBP-1 (log 2 transformed). Also in this model FGFBP-1 can add prognostic information to the risk score.

TABLE-US-00005 TABLE 5 Weighted proportional hazard model combining the ABC score with FGFBP-1 (log2 transformed) Hazard Ratio (HR) 95%-CI HR P-Value ABC score 1.1418 1.0305-1.2652 0.0113 FGFBP-1 (log2 2.604 1.7379-3.9016 <0.0001 transformed)

[0339] Table 6 shows the estimated c-indexes of FGFBP-1 alone, of the CHADS.sub.2, the CHA.sub.2DS.sub.2-VASc, the ABC score and of the weighted proportional hazard model combining the CHADS.sub.2, the CHA.sub.2DS.sub.2-VASc, the ABC score with FGFBP-1 (log 2) on the case cohort selection.

[0340] It can be seen that the addition of FGFBP-1 improves the c-index of all three risk models. The improvements are 0.040, 0.025 and 0.042 for the CHADS.sub.2, the CHA.sub.2DS.sub.2-VASc, the ABC score respectively.

[0341] Table 6 shows the estimated c-indexes of NTproBNP alone, of ESM-1 alone, of Ang-2 alone, of IGFBP-7 alone, of the CHA.sub.2DS.sub.2-VASc score and of the weighted proportional hazard model combining the CHA.sub.2DS.sub.2-VASc score with NTproBNP (log 2), with ESM-1 (log 2), with ANG-2 (log 2), with IGFBP-7 (log 2) on the case cohort selec-tion. It can be seen that the addition of all biomarkers improve the c-index of the CHA.sub.2DS.sub.2-VASc score. The improvements of the the CHA.sub.2DS.sub.2-VASc score are 0.002, 0.064, 0.036 and 0.006 for NTproBNP, ESM-1, Ang-2, IGFBP-7.

[0342] In this context it is interesting, that FGFBP1 has only low correlation with established markers (NTproBNP and ChadsVasc) as well as with ESM-1: a) FGFBP1 vs NTproBNP correlation coefficient=0.04, b) FGFBP1 vs ESM1 correlation coefficient=0.31 c) FGFBP1 vs CHADsVASc. correlation coefficient=0.05. These data suggest, that FGFBP1 provides complementary information and combinations of FGFBP1 and/or NTproBNP and/or ESM1 and/or CHADsVASc markers may provide im-proved detection of patients at high risk of stroke vs each marker alone.

TABLE-US-00006 TABLE 6 C-indexes of FGFBP-1, the ABC, CHADS.sub.2 and CHA.sub.2DS.sub.2-VASc score and their combination with FGFBP-1. C-indexes of ESM-1, NTproBNP, IGFBP-7, Ang-2 the CHA.sub.2DS.sub.2-VASc score and their combination with ESM-1, NTproBNP, IGFBP-7, Ang-2. C-Index FGFBP-1 univariate 0.609 CHADS.sub.2 0.650 CHADS.sub.2 + FGFBP-1 0.690 CHA.sub.2DS.sub.2-VASc 0.674 CHA.sub.2DS.sub.2-VASc + FGFBP-1 0.698 ABC score 0.648 ABC score + FGFBP-1 0.690 NTproBNP univariate 0.651 CHA.sub.2DS.sub.2-VASc + NTproBNP 0.676 ESM-1 univariate 0.708 CHA.sub.2DS.sub.2-VASc + ESM-1 0.738 Ang-2 univariate 0.696 CHA.sub.2DS.sub.2-VASc + Ang-2 0.710 IGFBP-7 univariate 0.652 CHA.sub.2DS.sub.2-VASc + IGFBP-7 0.680

[0343] Case Studies

[0344] There is growing interest in knowing and reducing the ischemic stroke risk also in patients without atrial fibrillation (Yao X et al, Am Heart J. 2018; 199:137-143). For example, predicting the stroke risk is essential to establish optimum treatment strategies by identifying and including these patients at high stroke risk into drug studies with oral anticoagulation.

[0345] The CHA2DS2-VASc score, for example, predicts incidence of ischemic stroke also in patients without atrial fibrillation, but with a lower absolute event rate (Mitchell L B et al, Heart. 2014; 100:1524-30). Therefore, it is less clear, if and at what CHA2DS2-VASc score these patients without atrial fibrillation should receive oral anticoagulation (OAC) and at which dose, so that biomarkers such as FGFBP-1 help to assess the need for therapy and effectiveness of OAC.

[0346] A 76-year old female patient with hypertension and no history of atrial fibrillation presents in sinus rhythm. FGFBP-1 is determined in an EDTA plasma sample obtained from the patient. The clinical information of the CHA2DS2-VASc score (advanced age and hypertension) indicate a certain stroke risk, and in addition the FGFBP-1 value is above a reference value. The elevated titer is indicative of high stroke risk. As consequence the patient is admitted to an anticoagulation therapy.

[0347] A 65-year old male patient without a history of atrial fibrillation requests a checkup at the doctor's office. The presents in sinus rhythm, however structural heart disease is diagnosed. Because of the history of stroke and high overall CHA2DS2-VASc score, the patient already receives direct oral anticoagulation therapy at low dose. In order to determine the current stroke risk and to conclude on eventual therapy change, FGFBP-1 is measured in a serum sample obtained from the patient. The observed FGFBP-1 value is above a reference value.

[0348] The elevated FGFBP-1 titers and other risk parameters (history of stroke) are indicative of a high residual stroke risk that is higher than the bleeding risk (assessed with other clinical information). As consequence the dosage of the anticoagulation therapy is increased.

[0349] A 68-year old obese female patient with Diabetes Mellitus and heart failure with reduced ejection fraction presents with acute symptoms of shortness of breath. In prior visits, the patient has no history of atrial fibrillation. According to a high overall CHA2DS2-VASc risk score, the physician decided to start oral anticoagulation (low dose) even in the absence of AFib. The FGFBP-1 level is determined before and after onset of anticoagulation. The patient is now wondering whether the anticoagulation therapy is effective and still necessary.

[0350] In order to specify the current risk of stroke, FGPBP-1 is determined in an EDTA sample obtained from the patient. The observed FGFBP-1 value is below a reference value and lower as compared to the treatment start. The reduced FGFBP-1 titers are indicative of an effective anticoagulation therapy. As consequence, the anticoagulation therapy is maintained.