Patent Description:
It was clarified that nematodes exhibit attraction behavior toward urine samples of cancer patients and exhibit avoidance behavior against urine samples of healthy individuals. Based on such tactic behavior of nematodes, a method for diagnosing cancer has been developed (Patent Literature <NUM>). In the evaluation system of this method, a urine sample is diluted about <NUM>-fold. When nematodes exhibit attraction behavior toward the diluted sample, then it can be determined that the subject from which the sample is derived, has a cancer. When the dilution ratio of the sample is high, needless to say, the accuracy of determination greatly decreases (Patent Literature <NUM>).

Patent Literature <NUM> is directed to a method for evaluating chemotaxis behavior of nematodes against odorants based on their sense of smell, and a petri dish used for the method.

The present inventors considered that it is demanded to develop a method for highly sensitively and highly specifically detecting a kidney cancer or a method for highly sensitively and highly specifically detecting a kidney cancer in dialysis patients who are reported to develop a kidney cancer at a high rate.

The present invention provides a method for detecting a kidney cancer according to claim <NUM>.

According to Patent Literature <NUM> (<CIT>), nematodes exhibit attraction behavior toward urine samples obtained from cancer patients; whereas nematodes exhibit avoidance behavior against urine samples obtained from healthy individuals. Particularly, if a urine sample is diluted <NUM>-fold with water, highly sensitive and highly specific detection can be attained; however, as the dilution ratio increases (for example, to a dilution ratio of <NUM> or more), the detection sensitivity and specificity decrease.

When the present inventors have found that when urine derived from patients having a kidney cancer was diluted at the dilution ratio mentioned above and evaluated in an evaluation system for attraction behavior of nematodes, the detection sensitivity and specificity were low compared to those for other cancers. On the other hand, the present inventors have found that when urine samples derived from patients having a kidney cancer was diluted at a higher ratio, and used in the evaluation system, the sensitivity and specificity for detecting a kidney cancer was dramatically improved. The present inventors also have found that cancer patients can be distinguished from patients having a kidney disease by subjecting a urine sample diluted at the higher dilution ratio to the above evaluation system. The present invention has been attained based on these findings.

The subject matter of the present invention is described in the appended claims.

As used herein, the "nematodes" refer to Caenorhabditis elegans. Nematode species is a popular organism raised as a model organism and studied worldwide in biological researches. Nematodes have features of being easily raised and having a good sense of smelling.

As used herein, the term "cancer" refers to a cancer such as a kidney cancer, stomach cancer, uterine cancer, liver cancer, breast cancer, colorectal cancer, esophageal cancer, pancreatic cancer, prostate cancer, bile duct cancer, lung cancer, blood cancer, leukemia and lymphoma. The methods of the present invention are for detecting kidney cancer in a subject having a chronic kidney disease.

As used herein, the "kidney cancer" refers to a cancer developed in the kidney including renal cell cancer and renal pelvis cancer.

The stages of renal cell cancer can be determined based on the TNM classification shown in Table <NUM>-<NUM>.

Further, the stages of a kidney cancer can be determined based on the following Table <NUM>-<NUM>.

The stage (any one of stages I, II, III and IV) of renal pelvis/ureter cancer can be determined based on, e.g., "<NPL>.

As used herein, the "kidney disease" refers to a disease or a disease state caused by hypofunction of the kidney. A kidney disease is caused basically when the glomerulus and tubule of the kidney are damaged.

The function of the kidney once damaged is not recovered in most cases, and a pathological condition called a chronic kidney disease or chronic renal failure is developed.

The chronic kidney disease is defined as the disease state where, for example, one or both of the following states (<NUM>) and (<NUM>) continue for <NUM> months or more:.

The eGFR of a man can be calculated based on the following expression:
eGFR (mL/min/<NUM><NUM>) = <NUM> × serum creatinine level (mg/dL)-<NUM> × age-<NUM>.

The eGFR of a woman is obtained by multiplying the eGFR of a man by <NUM>.

The severity of a kidney disease can be evaluated further based on the estimated glomerular filtration rate.

As used herein, the "subject" refers to a mammal, for example, a human. If the subject is a human, the subject is sometimes called as a patient. The subject may be a subject having a cancer or a subject suspected of having a cancer (hereinafter sometimes referred to simply as a " subject suspected of having a cancer").

As used herein, "about" means that the range plus or minus <NUM>% or <NUM>% of the numerical value following "about" is included.

As used herein, the "tactic behavior" refers to attraction behavior or avoidance behavior. The attraction behavior refers to an action to reduce the physical distance from a certain substance; whereas the avoidance behavior is an action to increase the physical distance from a certain substance. The substance inducing the attraction behavior is referred to as an attractant; whereas the substance inducing the avoidance behavior is referred to as a repellent.

Nematodes (C. elegans) are inherently attracted by an attractant and escape from a repellent by sensing smell. The action to migrate towards an attractant is referred to as attraction behavior; whereas the action to escape from a repellent is referred to as avoidance behavior. The attraction behavior and the avoidance behavior are collectively referred to as tactic behavior. Nematodes exhibit attraction behavior toward urine samples from cancer patients and avoidance behavior against urine samples from healthy individuals.

As used herein, the "method for detecting a cancer" and analogous expressions may be rephrased by a "method for obtaining preliminary information about the presence or absence of a cancer", a "method for obtaining preliminary information for diagnosing a cancer", a "preliminary method for diagnosing a cancer", a "method for detecting possibility of cancer" or a "method for detecting cancer cells". In the present specification, the method for detecting a kidney cancer may have industrial availability.

In the present invention, the subject may be a human. In the present invention, the subject may be, for example, a subject suspected of having a cancer or a subject having a cancer (for example, cancer except a kidney cancer or a kidney cancer). According to the present invention, the subject is a subject having a chronic kidney disease and suspected of having a cancer. In an embodiment of the present invention, the subject may be a subject having a cancer except a kidney cancer and a chronic kidney disease. In an embodiment of the present invention, the subject may be a subject having a kidney cancer and a chronic kidney disease. In an embodiment of the present invention, the subject may be a subject receiving dialysis. In an embodiment of the present invention, the subject may be a patient having a chronic kidney disease having a CDK stage selected from the group consisting of <NUM>, <NUM>, 3a, 3b, <NUM> and <NUM>. In the present invention, a kidney cancer of a patient having a chronic kidney disease can be detected even if the disease is in any one of CDK stages.

In the present invention, the kidney cancer to be detected is cancer selected from cancers at stage I, II, III and IV. The method of the present invention is suitable for detecting any one of the cancers at stage I, II, III and IV; however, the method is suitable for an early-stage cancer (i.e., stage-I cancer and stage-II cancer), and more specifically, suitable for detecting a stage-I kidney cancer.

In an embodiment of the present invention, a dilution series can be employed to arrive at a predetermined ratio according to the claims. The dilution series may be prepared from any one of a plurality of predetermined ratios, such as a dilution series of <NUM>- to <NUM>-fold, a dilution series ranging from <NUM>- to <NUM>-fold or a dilution series of <NUM>-fold.

In the present invention, a urine sample may be diluted with a solvent such as water, distilled water or sterile water.

Whether or not nematodes exhibit attraction behavior toward a urine sample can be determined by observing nematodes' behavior, i.e., moving closer to or away from a urine sample placed at a predetermined distance (for example, <NUM> to <NUM>) from the nematodes. When some of nematodes moved closer to the urine sample and others moved away from the urine sample, if the ratio of nematodes moving closer to the urine sample is higher than that of nematodes moving away from the urine sample, it can be determined that nematodes exhibit attraction behavior toward a test sample. In contrast, if the ratio of nematodes moving closer to the urine sample is lower than that of nematodes moving away from the urine sample, it can be determined that nematodes exhibit avoidance behavior against the urine sample.

Alternatively, a tactic index is obtained in accordance with, e.g., the following expression. Based on the index, whether nematodes exhibit attraction behavior or avoidance behavior may be determined.

The tactic index is a numerical value ranging from - <NUM> to +<NUM>. When attraction behavior is exhibited, the index results in a positive value; whereas when avoidance behavior is exhibited, the index results in a negative value. It can be interpreted that the larger the absolute value of the tactic index, the more distinctive the tactic behavior.

In the present invention, tactic behavior of nematodes to samples diluted at different predetermined ratios is evaluated.

According to Patent Literature <NUM>, cancers except a kidney cancer are widely detected based on tactic behavior of nematodes. The tactic behavior of nematodes can be most highly sensitively and highly specifically determined by diluting a urine-sample <NUM>- to <NUM>-fold, preferably about <NUM>-fold. In contrast, according to the present invention, a cancer of the kidney, which is an organ producing urine, can be highly sensitively and highly specifically determined at a predetermined ratio of <NUM>,<NUM> or more in combination with a predetermined ratio of <NUM> to <NUM>. Accordingly, urine derived from a predetermined subject is diluted at a first predetermined ratio to prepare a sample and urine derived from the predetermined subject is diluted at a second predetermined ratio to prepare a sample. Then, tactic behavior of nematodes to each of the samples is evaluated. In this manner, it is determined that the subject has a kidney cancer.

The second predetermined ratio may be a ratio of, for example, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more or <NUM> or more. In the present invention, the second predetermined ratio, may be a ratio ranging from, for example, a ratio ranging from <NUM> to <NUM>, a ratio ranging from <NUM> to <NUM>, a ratio ranging from <NUM> to <NUM>, a ratio ranging from <NUM> to <NUM>, a ratio ranging from <NUM> to <NUM> or a ratio ranging from <NUM> to <NUM>. In a specific embodiment, the second predetermined ratio may be, for example, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM> or about <NUM>. As described above, dilution series may be prepared and put in use.

If nematodes exhibit attraction behavior toward a sample derived from the urine of a predetermined subject and diluted at a first predetermined ratio, then it can be determined that the subject has a cancer except a kidney cancer or a possibility thereof. In contrast, if nematodes exhibit attraction behavior toward a sample derived from the urine of the predetermined subject and diluted at a second predetermined ratio, then it can be determined that the subject has a kidney cancer. If nematodes exhibit attraction behavior toward a sample derived from the urine of a predetermined subject and diluted at a first predetermined ratio and avoidance behavior against a sample derived from the urine of the predetermined subject and diluted at a second predetermined ratio, then it can be determined that the subject has a cancer except a kidney cancer or a possibility thereof. If nematodes exhibit attraction behavior toward a sample derived from the urine of a predetermined subject and diluted at a second predetermined ratio and avoidance behavior against a sample derived from the urine of the predetermined subject and diluted at a first predetermined ratio, then it can be determined that the subject has a kidney cancer.

A diagnostic kit for a kidney cancer, containing nematodes, can be used in the method of the present invention.

Following detection of the kidney cancer, the subject may be treated with a suitable cancer therapy. A kidney cancer can be treated by a cancer therapy (for example, administration of an anticancer drug, radiation therapy, immunotherapy to a kidney cancer, or surgical resection thereof) suitable for a kidney cancer.

Now, the present invention will be described by way of Examples; however, Examples are just examples and should not be construed as limiting the scope of the invention.

In patients having a kidney disease, the amount of urine is low and also abnormality in urine is sometimes found. In the patients having a kidney disease receiving dialysis, the rate of developing cancer is high. In this example, tests were made as to whether a cancer can be determined based on olfactory perception of nematodes and as to whether a cancer is diagnostically distinguished from a kidney disease.

First, urine samples were obtained from <NUM> patients having a kidney disease (of them, <NUM> patients had a kidney cancer, <NUM> patients received dialysis and a single patient had eosinophilic adenoma). The patients having a kidney cancer, which were all diagnosed as a kidney cancer by doctor, had stage-I kidney cancer having a tumor size (in a specimen) of pT1a (<NUM> or less as a primary tumor) in the TNM classification. The detail information about the patients are shown in following Table <NUM>.

As shown in <FIG>, a urine sample was diluted <NUM>-fold with sterile water. The diluted urine sample was applied on a marginal portion <NUM> on a flat-surface agar plate <NUM>, nematodes were applied at the center <NUM> of the agar plate. Whether nematodes exhibit attraction behavior toward or avoidance behavior against the urine sample was observed. Whether nematodes exhibit attraction behavior or avoidance behavior was determined based on the following tactic index.

<MAT> wherein region <NUM> in one of the three regions in the agar plate <NUM> divided by two dash-dot-dot-dash lines and close to the urine sample; whereas, region <NUM> is one of the three regions distant from urine sample.

The results were as shown in <FIG> and <FIG>.

As shown in <FIG>, nematodes exhibited attraction behavior toward some of the urine samples (<NUM>-fold dilution) derived from cancer patients. Cancer was successfully detected. In contrast, nematodes exhibited avoidance behavior against all of the urine samples of patients having a kidney disease alone. However, as shown in <FIG>, nematodes exhibited attraction behavior toward some of the urine samples (<NUM>-fold dilution) derived from cancer patients, but the behavior was less distinctive. As shown in <FIG>, the urine samples (<NUM>-fold dilution), which failed to induce attraction behavior of nematodes, were outstanding.

The same urinalysis as above was carried out by varying the dilution ratios of the urine samples. <FIG> and <FIG> show the urinalysis results obtained in urine samples diluted <NUM>,<NUM>-fold and <NUM>,<NUM>-fold.

As shown in <FIG>, in the urinalysis using urine samples diluted <NUM>,<NUM>-fold, nematodes exhibited attraction behavior toward a large number of samples of urine derived from cancer patients. As shown in <FIG>, in the urinalysis using urine samples diluted <NUM>,<NUM>-fold, nematodes exhibited attraction behavior toward a larger number of samples of urine derived from cancer patients. As shown in <FIG>, in the urinalysis using urine samples diluted <NUM>,<NUM>-fold, attraction behavior toward a plurality of samples were stably and distinctively detected. Also, as shown in <FIG> and <FIG>, avoidance behavior against a plurality of samples of urine derived from patients having a kidney disease was stably and distinctively detected.

As is obvious from Table <NUM>, patients in different stages of chronic kidney disease (CKD) were included as test subjects in this time. As shown in <FIG> and <FIG>, it was not observed that the CKD stages of test subjects influence diagnosis of a kidney cancer. Note that, in <FIG>, the 4th sample from the left was derived from a CDK stage-<NUM> patient; the 10th sample from the left was derived from a CDK stage-3b patient.

From Examples of the present invention, it was clearly demonstrated that detection sensitivity and specificity of a cancer are improved by increasing the dilution ratio of a urine sample (in other words, by thinning a urine sample). It was also demonstrated that nematodes stably and distinctively exhibit avoidance behavior against a plurality of samples of urine derived from patients having a kidney disease under the same conditions for dilution ratios. As described in the above, in the evaluation system using tactic behavior of nematodes, kidney cancer patients can be highly sensitively and highly specifically detected by highly diluting a urine sample. Also, in the evaluation system using tactic behavior of nematodes, patients having a kidney cancer (for example, No. <NUM>) can be distinguished from patients having a kidney disease. Further, eosinophilic adenoma (No. <NUM>) can be distinguished from a cancer in the evaluation system of the present invention.

Dialysis patients are known to have a high incidence of cancer compared to non-dialysis patients. From the results of the invention, it was suggested that urinalysis using nematodes can be used for monitoring development of a cancer in dialysis patients. Since pT1a or stage I kidney cancer can be diagnosed by the method of the present invention, it was found that the method of the present invention is useful for early diagnosis of a kidney cancer. In particular, since dialysis patients are reported to develop a cancer at a high rate, the method of the invention can open the way for early diagnosis of a kidney cancer by urinalysis in the dialysis patients.

Claim 1:
A method for detecting a kidney cancer in a subject having a chronic kidney disease, comprising:
diluting a urine sample obtained from the subject at a first predetermined ratio;
diluting the urine sample obtained from the subject at a second predetermined ratio; and
determining whether or not nematodes exhibit attraction behavior toward the diluted urine samples,
wherein the first predetermined ratio is a ratio ranging from <NUM> to <NUM>, and the second predetermined ratio is a ratio of <NUM> or more; and
wherein, when nematodes exhibit attraction behavior toward the sample diluted at the second predetermined ratio, and the nematodes exhibit avoidance behavior against the sample diluted at the first predetermined ratio, then it is determined that the subject from which the urine sample is derived, has a kidney cancer.