WO2025187382A1 - Diagnostic agent for cardiac function - Google Patents

Abstract

This diagnostic agent for cardiac function contains a compound represented by general formula (1-0) as an active ingredient. [In general formula (1-0), R represents -O(CH₂)_n-, -O(CH₂)_nOC₂H₄-, -CH₂O(CH₂)_n-, or -CH₂O(CH₂)_nOC₂H₄-, n represents an integer of 1-5, and Q¹ represents F or -OCH₃.]

Description

Diagnostic agent for cardiac function

The present invention relates to a diagnostic agent for cardiac function.

Positron emission tomography (PET) is used in a variety of diagnostic applications. For example, Patent Document 1 discloses a compound suitable for detecting mitochondrial complex-1 as a probe that can be used in PET.

International Publication No. 2014/30709

The use of the compounds disclosed in Patent Document 1 for diagnostic purposes of cardiac function has not been reported to date.

Traditionally, early detection of cardiac dysfunction has been achieved through electrocardiogram measurements and blood biochemistry tests. However, diagnosis using an electrocardiogram requires that electrocardiographic abnormalities occur during the measurement period, making it a method that is prone to overlooking abnormalities. In recent years, continuous monitoring using devices such as Holter monitors has become more common, but while this is a simple test, it must be worn for more than 24 hours, placing a significant burden on patients due to long-term testing. In blood biochemistry tests, enzymes such as creatine kinase (CK) and aspartate aminotransferase (AST) released into the blood in association with myocardial cell destruction, such as myocardial infarction, only last for approximately 24 hours after the onset of the disease, making pinpoint testing necessary. Furthermore, the activity of these enzymes can show similar changes to those seen in myocardial infarction even in conditions originating from skeletal muscle, making them problematic as indicators of myocardial dysfunction.

The main imaging diagnostic methods for the heart are ultrasound, CT, and MRI, but these are all methods for evaluating the shape and movement of the myocardium, as well as the physical quantity of blood ejection. As such, while they are suitable for measuring symptoms in the later stages of the disease, they are not suitable for early detection.

Some cardiac examinations using nuclear medicine, such as PET, use rubidium ( ^82Rb ), ammonia ([ ^13N ] _NH3 ), and water ([ ¹⁵ ] _H2O ), but these primarily measure changes in myocardial blood flow distribution due to myocardial ischemia and do not measure the biochemical functions of the myocardium that are directly linked to diagnosing pathology or assessing the effectiveness of treatment. PET also tests myocardial function, such as measuring myocardial oxygen consumption using [ ^11C ]Acetate, but because ^11C has a short half-life of just 20 minutes, it can only be used in PET facilities equipped with a cyclotron, and is not widely used. As a PET probe for the heart, [ ¹⁸ F]FDG is used to confirm the viability of myocardial cells after myocardial infarction and to test for cardiac sarcoidosis, taking advantage of the property of [ ¹⁸ F]FDG that it is easily distributed in inflammation.However, because the tissue accumulation of [ ¹⁸ F]FDG depends on the blood glucose concentration, an overnight fasting period is required before the test, and diabetic patients with high blood glucose concentrations are difficult to test.

In light of the above circumstances, the present invention aims to provide a diagnostic agent for cardiac function that can sensitively diagnose changes in cardiac function.

The present invention relates to a diagnostic agent for cardiac function containing a compound represented by general formula (1-0) (hereinafter also referred to as "compound (1-0)") as an active ingredient.

In the general formula (1-0), R represents —O(CH ₂ ) _n —, —O(CH ₂ ) _n OC ₂ H ₄ —, —CH ₂ O(CH ₂ ) _n — or —CH ₂ O(CH ₂ ) _n OC ₂ H ₄ —, n represents an integer of 1 to 5, and Q ¹ represents F or —OCH ₃ .

Compound (1-0) is known to be useful for detecting mitochondrial complex-I (hereinafter also referred to as "MC-I"). The cardiac function diagnostic agent of the present invention accumulates in the heart, and the amount of accumulation is proportional to the cardiac MC-I activity, making it suitable for use in diagnosing cardiac function. Furthermore, as shown in the examples below, the cardiac function diagnostic agent of the present invention can diagnose cardiac function based on the detection of MC-I activity even in conditions in which no changes in biochemical or morphological indicators are observed. Therefore, the diagnostic agent of the present invention can sensitively diagnose changes in cardiac function. As a result, changes in cardiac function can also be diagnosed at an early stage.

In the diagnostic agent, ^Q1 may be ^18F or ^-O11CH3 . This enables the compound to emit positrons. The positrons emitted from the compound immediately combine _with electrons to emit gamma rays (annihilation radiation). By measuring these gamma rays with a device used in positron emission tomography (PET), the compound accumulating in the heart can be imaged quantitatively and over time. In other words, the compound can also be used as a labeled compound for PET.

The present invention can also be considered a method for diagnosing cardiac function, comprising the steps of administering the diagnostic agent to a subject, detecting compound (1-0) that has accumulated in the heart, and quantitatively analyzing the amount of compound (1-0) accumulated in the heart.

The present invention can also be understood as a compound represented by general formula (1-0) for use in diagnosing cardiac function. The present invention can also be understood as the use of a compound represented by general formula (1-0) in the manufacture of a diagnostic agent for cardiac function.

Because the diagnostic agent of the present invention can sensitively diagnose changes in cardiac function, it can also be used to evaluate side effects of drugs on the heart. In other words, the diagnostic agent of the present invention can also be considered an agent for evaluating side effects of drugs on the heart.

The present invention includes, for example, the following inventions.
[1]
A diagnostic agent for cardiac function, comprising a compound represented by general formula (1-0) as an active ingredient.
[In general formula (1-0), R represents -O( _CH2 ) _n- , -O( _CH2 ) _nOC2H4- , _-CH2O ( _CH2 ) _n- or _-CH2O ( _{CH2 ) nOC2H4-} , _n represents an integer of 1 to ₅ , and ^Q1 represents F or _{-OCH3 .} ]
[2]
An agent for evaluating side effects of drugs on the heart, which comprises a compound represented by general formula (1-0) as an active ingredient.
[In general formula (1-0), R represents -O( _CH2 ) _n- , -O( _CH2 ) _nOC2H4- , _-CH2O ( _CH2 ) _n- or _-CH2O ( _{CH2 ) nOC2H4-} , _n represents an integer of 1 to ₅ , and ^Q1 represents F or _{-OCH3 .} ]
[3]
The agent according to [1] or [2], wherein the active ingredient is a compound represented by general formula (1-0'):
[In general formula (1-0'), R, n, and ^Q1 have the same meanings as R, n, and ^Q1 in general formula (1-0)]
[4]
The agent according to any one of [1] to [3], wherein the active ingredient is a compound represented by general formula (1-0″).
[In general formula (1-0″), n and ^Q1 have the same meanings as n and ^Q1 in general formula (1-0)]
[5]
The agent according to any one of [1] to [4], wherein the active ingredient is a compound represented by the following formula (1):
[In formula (1), ^Q1 has the same meaning as ^Q1 in general formula (1-0)]
[6]
The agent according to any one of [1] to [5], wherein Q ¹ is ¹⁸ F or —O ¹¹ CH ₃ .
[7]
1. A method for diagnosing cardiac function in a subject, comprising:
A diagnostic method comprising the steps of: administering the agent according to any one of [1] to [6] to a subject; detecting the active ingredient accumulated in the heart; and quantitatively analyzing the amount of accumulation of the active ingredient in the heart.
[8]
A method for evaluating side effects of a drug on the heart, comprising:
administering the agent to a subject;
An evaluation method comprising the steps of: administering the agent according to any one of [1] to [6] to a subject who has been administered the agent; detecting the active ingredient that has accumulated in the heart; and quantitatively analyzing the amount of accumulation of the active ingredient in the heart.
[9]
The agent according to any one of [1] to [6], for use in diagnosing cardiac function.
[10]
The agent according to any one of [1] to [6], which is used to evaluate side effects of a drug on the heart.
[11]
Use of the active ingredient or agent according to any one of [1] to [6] in the manufacture of a diagnostic agent for cardiac function.
[12]
Use of the active ingredient or agent according to any one of [1] to [6] in the manufacture of an agent for evaluating side effects of drugs on the heart.

The present invention makes it possible to provide a diagnostic agent for cardiac function that can sensitively diagnose changes in cardiac function.

(A) Graph showing the amount of [ ¹⁸ F]BCPP-BF accumulated in the heart (radioactivity accumulated in SUV) (B) Graph showing the amount of [ ¹⁸ F]FDG accumulated in the heart (radioactivity accumulated in SUV) (A) Graph showing the accumulation of [ ¹⁸ F]BCPP-BF in the heart (radioactivity accumulation (SUV)). (B) Graph showing the accumulation of [ ¹⁸ F]BMS in the heart (radioactivity accumulation (SUV)). 1 is a graph showing the amount of [ ¹⁸ F]BCPP-BF accumulated in the heart (radioactivity accumulated in units of units (SUV)).

The following describes in detail the embodiments for implementing the present invention. However, the present invention is not limited to the following embodiments.

The cardiac function diagnostic agent according to this embodiment (hereinafter also referred to simply as the "diagnostic agent") contains a compound represented by general formula (1-0) as an active ingredient. Note that, in this specification, all isotopes of each atom are included unless otherwise specified.

In compound (1-0), R is —O(CH ₂ ) _n —, —O(CH ₂ ) _n OC ₂ H ₄ —, —CH ₂ O(CH ₂ ) _n — or —CH ₂ O(CH ₂ ) _n OC ₂ H ₄ —. R is preferably —O(CH ₂ ) _n — or —O(CH ₂ ) _n OC ₂ H ₄ —, and more preferably —O(CH ₂ ) _n —.

In compound (1-0), n is an integer of 1 to 5, preferably an integer of 2 to 5, more preferably an integer of 3 to 5, and even more preferably 4.

In compound (1-0), Q ¹ is F or —OCH ₃ , and preferably ¹⁸ F or —O ¹¹ CH _3. Compound (1-0) in which Q ¹ is ¹⁸ F or —O ¹¹ CH ₃ is capable of emitting positrons and is therefore suitable as a labeled compound (PET probe) for use in the PET method. Furthermore, when Q ¹ is —O ¹¹ CH ₃ , the half-life is as short as 20 minutes, making it possible to perform multiple measurements on the same subject per day. When ^{Q 1} is ¹⁸ F, the half-life is 110 minutes, which is longer than that of —O ¹¹ CH ₃ , making it possible to extend the time for a single measurement.

The bonding position of —OCH ₂ — bonded to the pyridazine ring and the bonding position of R on the pyridine ring are not particularly limited, but it is preferable that —OCH ₂ — bonded to the pyridazine ring is the 5-position of the pyridine ring and that R is the 2-position of the pyridine ring. The compound represented by the following general formula (1-0′) (hereinafter also referred to as “compound (1-0′)”) is a structural formula when —OCH ₂ — bonded to the pyridazine ring is the 5-position of the pyridine ring and R is the 2-position of the pyridine ring.

In the general formula (1-0'), R, n and ^Q1 have the same meanings as R, n and ^Q1 in the general formula (1-0).

Because compound (1-0) is more suitable for use in diagnosing cardiac function, it is preferable that compound (1-0) is a compound represented by general formula (1-0") (hereinafter also referred to as "compound (1-0")), and more preferably a compound represented by formula (1) (hereinafter also referred to as "compound (1)").

In the general formula (1-0″), n and ^Q1 have the same meanings as n and ^Q1 in the general formula (1-0).

In formula (1), ^Q1 has the same meaning as ^Q1 in general formula (1-0).

Compound (1-0) can be synthesized, for example, from the corresponding precursor. The same applies to compound (1-0'), compound (1-0"), and compound (1).

An example of a corresponding precursor of compound (1-0) is a compound represented by the following general formula (2-0) (hereinafter also referred to as "compound (2-0)"). An example of a corresponding precursor of compound (1-0'), compound (1-0"), and compound (1) is a compound in which R, the bonding position of -OCH ₂ - bonding to the pyridazine ring in the pyridine ring, and the bonding position of R are the same as those of compound (1-0'), compound (1-0"), and compound (1).

In the general formula (2-0), R has the same meaning as R in the general formula (1-0). ^Q2 represents a removable substituent (such as a substituted sulfonyloxy group, a halogen atom, or a hydroxyl group).

Examples of substituted sulfonyloxy groups include tosyloxy groups (-OTs), methanesulfonyloxy groups (-OMs), trifluoromethanesulfonyloxy groups (-OTf), and nitrobenzenesulfonyloxy groups (-ONs), with -OTs being preferred.

Halogen atoms include fluorine, chlorine, bromine, and iodine.

The precursor can be synthesized, for example, by the method described in WO 2014/30709.

Compound (1-0) accumulates specifically in the heart due to MC-1, and the amount of accumulation changes in correlation with the degree of cardiac function. That is, when cardiac function declines, the amount of accumulation of compound (1-0) decreases, and when cardiac function increases, the amount of accumulation of compound (1-0) increases. Therefore, the diagnostic agent of this embodiment is suitable for use in diagnosing cardiac function through measuring the amount of accumulation of compound (1-0). Decreasing cardiac function may be associated with, for example, cardiac (e.g., myocardial or cardiovascular) disease, disorder, or dysfunction. Diagnosis of cardiac function can also be referred to as evaluation of cardiac function.

The diagnostic agent of this embodiment can be used, for example, in methods for screening subjects with reduced cardiac function through the diagnosis of cardiac function (e.g., mass health checkups), methods for evaluating the side effects of drugs on the heart, and methods for observing cardiac function over time (e.g., monitoring the progress of symptoms that cause cardiac dysfunction, confirming the effectiveness of treatment, or predicting prognosis). Therefore, the diagnostic agent for cardiac function of this embodiment can also be considered, for example, as an agent for evaluating the side effects of drugs on the heart, or an agent for evaluating the effectiveness of treatment for symptoms that cause cardiac dysfunction.

The measurement of the accumulation amount of compound (1-0) can be carried out by, but not limited to, binding a fluorescent dye or the like to compound (1-0), or labeling compound (1-0) with a single photon nuclide ( ¹²³ I, ^99m Tc, etc.) or a positron nuclide to form a labeled compound, and then detecting the label. Positron labeling can be carried out, for example, by changing Q ¹ of compound (1-0) to —O ¹¹ CH ₃ or ¹⁸ F. In the case of positron labeling, the biodistribution of compound (1-0) can be quantitatively and time-dependently imaged by measuring annihilation radiation with an apparatus used in PET.

The diagnostic agent of this embodiment can be produced, for example, by dissolving compound (1-0) in any buffer solution. In this case, the diagnostic agent of this embodiment is provided as a solution, and may contain other components such as surfactants, preservatives, stabilizers, etc. in addition to the buffer components.

The method for diagnosing cardiac function according to this embodiment includes the steps of administering the diagnostic agent according to the present invention to a subject, detecting compound (1-0) that has accumulated in the heart, and quantitatively analyzing the amount of compound (1-0) accumulated in the heart.

The method for evaluating the side effects of a drug on the heart according to this embodiment includes a step of administering the drug to a subject, and can be carried out in the same manner as the diagnostic method described above, except that the subject in the diagnostic method described above is a subject to which the drug has been administered. The drug may be any drug.

Subjects include, but are not limited to, humans, monkeys, mice, and rats.

The method of administering the diagnostic agent to the subject is not particularly limited as long as compound (1-0) reaches the heart, but is usually administered intravenously.

The dose of the diagnostic agent is not particularly limited as long as it is a dose sufficient to detect compound (1-0) in the heart, and may be appropriately determined depending on the subject to which it is administered and the method for detecting compound (1-0). For example, when a diagnostic agent containing compound (1-0) in _which ^Q1 is ^18F or ^-O11CH3 is used to detect compound (1-0) using an apparatus used in PET, the dose of the diagnostic agent (hereinafter also referred to as the "administered radioactivity") may be 1 MBq/kg body weight to 1,000 MBq/kg body weight. The specific radioactivity of compound (1-0) may be 10 to 10,000 GBq/μmol. The administered radioactivity of the diagnostic agent depends on the sensitivity of the PET camera used and the volume of the subject, but in rodents (mice, rats), approximately 200 to 500 MBq/kg body weight is administered as 0.1 to 0.5 mL of physiological saline solution. For non-human primates (monkeys), 40-200 MBq/kg body weight is administered in 0.5-2 mL of saline, and for humans, 2-10 MBq/kg body weight is administered in 1-5 mL of saline solution.

The method for detecting compound (1-0) accumulated in the heart is not particularly limited, and can be carried out in accordance with known methods. For example, when a diagnostic agent containing compound (1-0) in which Q ¹ is ¹⁸ F or —O ¹¹ CH ₃ is used, compound (1-0) can be detected by PET. The measurement method in PET is not particularly limited, and can be carried out in accordance with known methods. Furthermore, for example, the method for measurement by PET may involve dynamic measurement for 60 minutes starting immediately after administration of the diagnostic agent, or it may involve waiting 30 to 40 minutes after administration of the diagnostic agent to allow compound (1-0) to sufficiently accumulate in the heart, and then carrying out PET measurement for 10 to 20 minutes.

The method for quantitatively analyzing the accumulation of compound (1-0) in the heart is not particularly limited and can be carried out in accordance with known methods. For example, the following method can be used. First, an accumulation image of compound (1-0) obtained by PET is overlaid on a morphological image of the heart obtained by CT measurement or the like to identify the PET image of the heart. Next, a region of interest is set on the PET image of the heart, and the value normalized by the weight of the subject individual and the amount of administered radioactivity is used as the accumulation amount of compound (1-0) in the heart. Furthermore, instead of a morphological image of the heart, an image obtained by PET using a probe capable of detecting the heart may be used.

The diagnostic method according to this embodiment may further include a step of comparing the quantitatively analyzed accumulation amount of compound (1-0) with a reference value to diagnose cardiac function.

The reference value may be set appropriately depending on the diagnostic purpose. For example, when the diagnostic method of this embodiment is performed in a group health checkup, the reference value may be a normal range determined in advance from the distribution of the accumulation amount of compound (1-0) in multiple subjects of the same type. In this case, whether the cardiac function of a specific subject is normal can be diagnosed depending on whether the quantitative analysis value of the accumulation amount in that specific subject falls within the normal range.

Furthermore, for example, when the diagnostic method of this embodiment is performed on a subject suffering from a condition that causes cardiac dysfunction (e.g., diabetes, dyslipidemia, myocardial infarction, cardiac sarcoidosis, etc.) for the purpose of monitoring the progress of the condition, confirming the effectiveness of treatment, or predicting the prognosis, the reference value may be the measurement result of the amount of accumulation of compound (1-0) in the subject at a certain point in time (e.g., when healthy, at the time of initial diagnosis, at the start of treatment, at the end of treatment, etc.).

Furthermore, for example, when the diagnostic method according to this embodiment is carried out to evaluate the side effects of a drug on the heart, the reference value may be the measurement result of the amount of accumulation of compound (1-0) in the subject to be administered the drug before taking the drug. In this case, if the quantitative analysis value of the amount of accumulation in the subject who has taken the drug is smaller than the reference value, it can be determined that the drug has side effects on the heart.

The present invention will be explained in more detail below based on examples. However, the present invention is not limited to these examples.

Test Example 1: Synthesis of PET probe
[ ¹⁸ F]BCPP-BF represented by the following formula was synthesized by the method described in a non-patent document (J. Labelled Comp. Radiopharm., 2013, Vol. 56, No. 11, pp. 553-561). The radiochemical purity of the obtained final product was 99% or more, and the specific radioactivity was 43.8 to 103.9 GBq/μmol.

As controls, [ ¹⁸ F]BMS-747158-02 (2-tert-butyl-4-chloro-5-[4-(2-fluoro-ethoxymethyl)-benzyloxy]-2H-pyridazin-3-one; hereinafter referred to as [ ¹⁸ F]BMS), which is known as a PET probe that recognizes mitochondrial Complex-1, ^{and 18} F-fluorodeoxyglucose ([ ¹⁸ F]FDG), which is known as a PET probe targeting the heart, were also prepared. The radiochemical purity of [ ¹⁸ F]BMS was 99% or more, and the specific radioactivity was 36.3 to 76.1 GBq/μmol. The radiochemical purity of [ ¹⁸ F]FDG was 99% or more.

Test Example 2: Evaluation of cardiac function in type 2 diabetes model rats
(Type 2 diabetes model rats)
Male Zucker Lepr ^fa /Lepr ^fa rats (hereinafter also referred to as "diabetic rats"), which develop a pathology similar to adult human type 2 diabetes, were purchased from Charles River Japan, Inc. and subjected to PET measurements at 5 and 26 weeks of age. Male Zucker Lepr ^fa /+ rats (hereinafter also referred to as "normal rats") were purchased from Charles River Japan, Inc. as controls.

(PET measurement)
Rats were anesthetized with isoflurane and secured in the gantry of an animal PET camera (SHR-38000, Hamamatsu Photonics). After 15 minutes of transmission measurement for attenuation correction, approximately 20 MBq/0.5 mL of [ ¹⁸ F]BCPP-BF was administered via the rat's tail vein, and emission measurement was performed for 60 minutes. A region of interest was set in the heart, and the amount of [ ¹⁸ F]BCPP-BF accumulated in the region of interest was calculated. The calculated amount of accumulation was then normalized by each individual's body weight and the administered radioactivity to determine the amount of [ ¹⁸ F]BCPP-BF accumulated in the heart (radioactivity accumulated volume (SUV)). As a control, the amount of [ ¹⁸ F]FDG accumulated in the heart (radioactive accumulated volume (SUV)) was measured in the same manner except that [ ¹⁸ F]FDG was used instead of [ ¹⁸ F]BCPP-BF.

(Measurement of blood glucose concentration)
Immediately after PET measurement, blood was collected from the rats and the blood glucose concentration was measured using an automatic biochemical analyzer (Hitachi High-Tech 7180).

(result)
Figure 1(A) is a graph showing the accumulation of [ ¹⁸ F]BCPP-BF in the heart (radioactivity accumulation (SUV)). Figure 1(B) is a graph showing the accumulation of [ ¹⁸ F]FDG in the heart (radioactivity accumulation (SUV)). Figure 1(B) shows the results measured in 26-week-old rats. In Figure 1, "★" indicates that the difference between the data from normal rats and diabetic rats of the same age was statistically significant (p<0.05).

If diabetes develops and blood sugar levels remain high for a long time, blood vessels become damaged, making patients more susceptible to complications such as heart disease, kidney disease, blindness, and leg amputation. It has also been reported that if diabetic patients experience attacks such as myocardial infarction or angina, they are at higher risk of heart failure and subsequent death (Circulation R., 2020, Vol. 126, pp. 1501-1525).

As shown in Figure 1(A), PET measurements using [ ¹⁸ F]BCPP-BF were able to detect cardiac dysfunction in diabetic rats at 5 and 26 weeks of age as a decline in mitochondrial function. At 26 weeks of age, blood glucose levels were 135.3 ± 17.9 mg/dL in normal rats and 588.3 ± 29.9 mg/dL in diabetic rats, indicating that the diabetic rats had reached a diabetic state with statistically significant elevated levels. Meanwhile, blood glucose levels at 5 weeks of age were 146.0 ± 13.8 mg/dL in normal rats and 171.4 ± 24.2 mg/dL in diabetic rats, tending to be slightly higher but not statistically significant. This indicates that PET measurements using [ ¹⁸ F]BCPP-BF can detect cardiac dysfunction due to diabetes at an extremely early stage.

On the other hand, as shown in Figure 1(B), PET measurements using [ ^18F ]FDG did not detect any significant difference compared to normal rats, even in 26-week-old diabetic rats that had reached a diabetic state showing statistically significant high values.

In a previous study using the same model rats as in this test example, no differences were found in the morphological changes or fibrosis of hearts isolated and evaluated from 14-week-old normal and diabetic rats (Am. J. Physiol. Heart Circ. Physiol., 2007, Vol. 293, H292-H298), and no differences were found between normal and diabetic rats in oxygen metabolism and ATP production rate from glucose evaluated in hearts isolated at 12 weeks of age (Am. J. Physiol. Heart Circ. Physiol., 2005, Vol. 288, H2102-H2110). Furthermore, no differences were observed between normal and diabetic rats in heart rate measured in vivo at 14 weeks of age or in the metabolic rate of ATP transfer via creatine kinase (CK) (CK flux), a biochemical indicator of myocardial energy metabolism (Physiol. Rep., 2015, 3(1), e12248).

These results show that by evaluating mitochondrial function using PET measurements with [ ^18F ]BCPP-BF, it is possible to detect diabetes-induced decline in cardiac function with great sensitivity and at an extremely early stage that cannot be detected by biochemical or morphological indicators.

Test Example 3: Evaluation of adverse cardiac effects associated with drug (acetaminophen) administration
Acetaminophen (hereinafter also referred to as "APAP"), a representative antipyretic analgesic widely used around the world, was administered to normal rats to evaluate its effects (side effects) on cardiac function.

(PET measurement)
APAP was administered intravenously at 100 mg/kg or 300 mg/kg via the tail vein of rats. As a control, rats were similarly administered intravenously with the solvent alone. 24 hours after administration of APAP or the solvent, the rats were subjected to PET measurement. The PET measurement procedure was the same as in Test Example 2. Furthermore, as a control, measurements were similarly performed using [ ¹⁸ F]BMS instead of [ ¹⁸ F]BCPP-BF.

(result)
Figure 2(A) is a graph showing the accumulation of [ ¹⁸ F]BCPP-BF in the heart (radioactivity accumulation (SUV)). Figure 2(B) is a graph showing the accumulation of [ ¹⁸ F]BMS in the heart (radioactivity accumulation (SUV)). In Figure 2, "★" indicates that the difference from the data of control rats (rats administered with the vehicle) was statistically significant (p<0.05).

It has been reported that excessive administration of APAP causes acute liver dysfunction (Semin. Liver Dis., 2008, Vol. 28, pp. 142-152) and acute kidney dysfunction (J. Am. Soc. Nephrol., 1995, Vol. 6, pp. 48-53). Previous studies by the present inventors have shown that these disorders can be detected early by PET measurements using [ ¹⁸ F]BCPP-BF in rats (EJNMMI Res., 2016, Vol. 6, pp. 82; Japanese Patent Publication No. 7005126).

On the other hand, perhaps because excessive APAP intake causes such severe damage to liver and kidney function, its effect on cardiac function has been overlooked. As shown in Figure 2(A), PET measurements using [ ^18F ]BCPP-BF revealed that 24 hours after intravenous administration of 100 mg/kg and 300 mg/kg of APAP also had a significant effect on cardiac mitochondrial function.

On the other hand, as shown in FIG. 2(B), PET measurements using [ ¹⁸ F]BMS failed to detect any significant difference in cardiac mitochondrial function 24 hours after APAP administration under the same conditions.

Previous research has shown that intravenous administration of 125 mg/kg APAP caused a significant transient increase in blood pressure two minutes after administration, but no significant difference from the vehicle-treated group was observed after three minutes. Meanwhile, no effect on heart rate was observed (J. Cardiovasc. Pharmacol. Therapeut., 2003, Vol. 8, pp. 277-284). Increased expression of inflammation-related genes was confirmed in the hearts of rats isolated 24 hours after oral administration of a high dose of 1000 mg/kg APAP, but the histological necrotic changes observed in the liver were not observed in the myocardium (Yonsei Med. J., 2012, Vol. 53, pp. 172-180).

These results demonstrate that the effects (side effects) of the drug (APAP) on cardiac function can be detected with extremely high sensitivity by evaluating mitochondrial function through PET measurements using [ ¹⁸ F]BCPP-BF.

Test Example 4: Evaluation of adverse cardiac effects associated with drug (doxorubicin) administration
Doxorubicin (hereinafter also referred to as "DOX") is an anticancer drug that inhibits DNA synthesis, suppresses cancer cell proliferation, and reduces tumor size (Med. Res. Rev., 2014, Vol. 34, pp. 106-135). While DOX is used to treat various cancers, including malignant lymphoma, lung cancer, gastrointestinal cancer, breast cancer, bladder tumors, and osteosarcoma, it is known to have side effects such as myocardial damage and heart failure, including shortness of breath, difficulty breathing, chest pain, leg swelling, and tachycardia. Therefore, it is contraindicated for patients with or a history of cardiac dysfunction. Therefore, a biomarker for early detection of DOX cardiotoxicity is needed. In this test example, DOX was administered to normal rats, and its effects on cardiac function (side effects) were evaluated.

(PET measurement)
DOX was administered intravenously at 5 mg/kg or 20 mg/kg via the tail vein of rats. Control rats were similarly administered intravenously with the solvent alone. The rats were subjected to PET measurements 0.5 hours, 24 hours, and 96 hours after administration of DOX or the solvent. The PET measurement procedure was the same as in Test Example 2.

(result)
Figure 3 is a graph showing the accumulation of [ ¹⁸ F]BCPP-BF in the heart (radioactivity accumulation (SUV)). In Figure 3, "★" indicates that the difference from the data of control rats (rats administered with the vehicle) at the same time after administration was statistically significant (p<0.05).

As shown in Figure 3, PET measurements using [ ¹⁸ F]BCPP-BF demonstrated a significant decrease in mitochondrial function 24 hours after DOX administration in high-dose (20 mg/kg) rats, and also in low-dose (5 mg/kg) rats 96 hours after DOX administration.

Previous studies have shown that 24 hours after intravenous administration of 20 mg/kg DOX, CK and troponin I (TnI), blood markers of myocardial dysfunction, failed to detect cardiac dysfunction. (12) Furthermore, even 24 hours after intravenous administration of a much higher dose of DOX (40 mg/kg), CK, TnI, lactate dehydrogenase (LDH), and fatty acid-binding protein 3 (FABP3) failed to detect cardiac dysfunction (PLoS ONE, 2012, Vol. 7, e38867). Furthermore, even after 3 weeks of repeated weekly intravenous administration of 3 mg/kg DOX, no changes were detected in cardiac function such as heart rate and cardiac output, or myocardial metabolism measured using TnI, LDH, and hyperpolarized [1- ¹³ C]pyruvate and [2- ¹³ C]pyruvate (Commun. Biol., 2020, Vol. 3, pp. 692).

These results demonstrate that the effects (side effects) of the drug (DOX) on cardiac function can be detected with extremely high sensitivity by evaluating mitochondrial function through PET measurements using [ ¹⁸ F]BCPP-BF.

Claims (6)

A diagnostic agent for cardiac function, comprising a compound represented by general formula (1-0) as an active ingredient.
[In general formula (1-0), R represents -O( _CH2 ) _n- , -O( _CH2 ) _nOC2H4- , _-CH2O ( _CH2 ) _n- or _-CH2O ( _{CH2 ) nOC2H4-} , _n represents an integer of 1 to ₅ , and ^Q1 represents F or _{-OCH3 .} ] An agent for evaluating side effects of drugs on the heart, which comprises a compound represented by general formula (1-0) as an active ingredient.
[In general formula (1-0), R represents -O( _CH2 ) _n- , -O( _CH2 ) _nOC2H4- , _-CH2O ( _CH2 ) _n- or _-CH2O ( _{CH2 ) nOC2H4-} , _n represents an integer of 1 to ₅ , and ^Q1 represents F or _{-OCH3 .} ] 3. The agent according to claim 1, wherein the active ingredient is a compound represented by general formula (1-0').
[In general formula (1-0'), R, n, and ^Q1 have the same meanings as R, n, and ^Q1 in general formula (1-0)] The agent according to claim 1 or 2, wherein the active ingredient is a compound represented by general formula (1-0″).
[In general formula (1-0″), n and ^Q1 have the same meanings as n and ^Q1 in general formula (1-0)] The agent according to claim 1 or 2, wherein the active ingredient is a compound represented by the following formula (1):
[In formula (1), ^Q1 has the same meaning as ^Q1 in general formula (1-0)] The agent according to claim 1 or 2, wherein Q ¹ is ¹⁸ F or —O ¹¹ CH ₃ .