JPH0564130B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for detecting tumors. The present invention also relates to monoclonal antibodies labeled with radionuclides. Reliable methods to specifically detect tumor location have been sought for many years. for example,
A method has been published to detect carcinoembryonic antigen (CEA) circulating in the blood and linked to human cancer. See U.S. Patent Nos. 3,663,684 and 3,697,638.
It is clear that the location of the tumor cannot be determined using these methods. Recently, a method has been proposed for detecting tumor-associated antigenic substances using antibodies labeled with radioisotope of iodine. Specifically, US Pat. No. 3,927,193 discloses a method using antibodies against CEA labeled with ¹²⁵ I and ¹³¹ I. According to this patent, in experiments conducted with male Syrian hamsters transfected with human signet ring cell carcinoma, labeled goat anti-CEA was injected and
They then examined the hamster's organs and found that the radioisotope was localized to the tumor. It has therefore been proposed that a person's tumor site can be determined by administering a parenteral solution of the antibody in vivo and then photoscanning the patient. Although radioiodinated antibodies were actually used,
It did not live up to the expectations that earlier studies had led to. For example, Goldenberg et al.
In 1978, he reported that he had some success in scanning humans using radioiodinated anti-CEA [N.Eng.J.Med., 298 , 1384-1388
(1978)]. However, due to residual background radioactivity, this success was limited using the subtraction method. Although not successful, Matsuha et al. reported that they determined that only 0.1% of the dose was localized to the tumor [N.Eng.J.Med., 303 , 5-10 ( 1980)]. but,
In some cases, imaging of the tumor was possible. Affinity purification of foreign tissue antisera to obtain antibodies used in conventional tumor imaging
purification) results in the loss of high-affinity antibodies and that the resulting antibodies are a mixture of antibodies specific for different antigenic determinants, with mostly low-affinity antibodies and non-specific reactions. It is well known that it is composed of antibodies that Monoclonal antibodies, on the other hand, can be chosen to exhibit high affinity for a given site on the antigen and low nonspecific binding. However, the inventors surprisingly found that despite the fact that monoclonal antibodies against tumor antigens labeled with radioactive iodine by well-known methods can still clearly demonstrate immunoreactivity in vitro. They discovered that it was not localized very much at the tumor site. This is probably due to loss of radioactive iodine by the labeled antibody. Therefore, there remains a need for reliable methods of accurately detecting tumor sites in vivo. According to the present invention, monoclonal antibodies or monoclonal antibody fragments directed against tumor antigens are prepared by coupling a chelating agent to the antibody using a chelated radionuclide, e.g., DTPA-conjugated ¹¹¹ In, and then combining the chelating agent and radioactive It is labeled by forming a complex with the nuclide. When such labeled antibodies or fragments thereof are injected into a tumor-bearing host, they rapidly and with a high degree of specificity concentrate on the tumor itself. In some cases, localization of distant metastases may occur and further indicate tumor spread. Tumor sites can be detected by photoscan. Mixtures of labeled monoclonal antibodies can also be used. It is therefore an object of the present invention to obtain monoclonal antibodies against tumor-associated antigens labeled with metal radionuclides. Another object of the invention is to provide an improved method for imaging tumors in infected hosts. The achievement of these and related objectives will be apparent from the accompanying drawings and detailed description below. As described above, according to the invention, monoclonal antibodies or fragments thereof directed against tumor-associated antigens are alternatively labeled with chelated radionuclides. Monoclonal antibodies useful in the invention are the products of well-known hybridoma methods. See, for example, the paper by Milstein and Kohler [Nature, 256 , 495-497 (1975)]. Basically, the method involves injecting a mouse or other suitable animal with an immunogen, in this case a tumor-associated antigen such as CEA. The immunized mice are then dissected and cells taken from their spleens are fused with myeloma cells to obtain hybrid cells called hybridomas, which can be reproduced in vitro. selectively culturing antibody-producing cell populations;
Screen to isolate individual clones.
Each individual clone secretes a single antibody species specific for a particular region (“determinant”) on the surface of the antigen molecule. Individual clones are further screened to determine those that produce antibodies with the highest affinity for the antibody and exhibit low non-specific binding.
for radioactive labeling (commonly isolated from ascites fluid)
The selected antibody is conjugated to a suitable chelating agent, and the radionuclide is then conjugated to the chelating agent. Chelating agents can be attached to antibodies using a variety of methods. Generally, since antibodies are polypeptides, chelating agents with reactive groups known for introducing residues can be used. Suitable reactive groups include: Ch−NCS

【formula】

[Formula] Ch−SO ₂ Cl

【formula】

【formula】

[Formula] Ch−N−SO ₂ −CH= CH ₂

[Formula] Ch−N ₂ + (from Ch−NH ₂ ) where Ch is the residue of a chelating agent. Suitable chelating agents include a variety of polydentate chelating agents whose ligands form a complex with the metal radionuclide. Examples of such chelating agents include polyaminocarboxylic acids of the following formula. In the formula, x is 0 or an integer (x=0 or x=1
is preferred), y = 1 or 2 (y = 1 is preferred), z = an integer of 1 to 7 (z = 1 or 7 is preferred), R is hydrogen, or the bond between the chelating agent and the antibody is or a group that affects the binding constant of the radionuclide chelator. Useful R groups include, among others:

[Formula] (wherein A is a group that completes the bond) is mentioned.
For example, A may be -N1/2 obtained by diazotization of _-NH2 , _-NH2 obtained by reduction of _-NO2 , and _-NO2 obtained by nitration of a phenyl nucleus. A is obtained by acetylating -NH ₂ by a known method

[Formula] may also be used. L is a group that is substituted and eliminated upon bonding, and is, for example, a halogen such as Cl, Br, or 1 (Br is preferred). Also, R is -CH ₃ or -CH ₂ C ₆ H ₄ OCH ₂ CO ₂
It may be H. In the case of polyaminocarboxylic acids, the linkage is completed through the carboxylic acid group itself, for example by formation of an acid anhydride intermediate. Krejcarek and
Tucker, Biochmical and Biophysical
See Research Communications, 77, 581 (1977). As the polyaminocarboxylic acid, polyaminoacetic acid is preferred. Specific polyaminocarboxylic acids that can be used include ethylenediaminotetraacetic acid (EDTA) and its derivatives, such as diethylenetriaminopentaacetic acid (DTPA), p-bromoacetamidophenyl (ethylenedinitrilotetraacetic acid) acid and 1-( p-aminophenyl)-ethylenediaminotetraacetic acid, the last compound being converted into a diazonium salt and coupled. Among these chelating agents, DTPA is preferred. Radionuclides that can be used in the present invention are those that form a complex with a multidentate chelating agent, or those that bind directly to antibodies under appropriate conditions. The radionuclide is selected to have a half-life and other radiation properties that allow it to be safely dumped and safely introduced into the body. A number of radionuclides have been investigated for use within the human body and would be useful in the present invention. These can be classified as follows. Polyphyrin (Formula 5), crown ether (Formula 6) and cryptand (Formula 7) chelators are most useful for binding radionuclides in the +2 oxidation state. For example, ^195m Pt, ⁵⁷ Ni, ⁵⁷ Co, ¹⁰⁵ Ag,
⁶⁷ Cu and ⁵² Mn form a stable complex in their +2 oxidation state. Chelating agents of formulas 1-5 and 9-12 form stable complexes with radionuclides in the +3 oxidation state. Among the radionuclides that form stable complexes in the +3 oxidation state are: That is, ⁵² Fe, ¹¹¹ In, ^113m In, ^99m Tc, ⁶⁸ Ga, ⁶⁷ Ga, ¹⁶⁹ Yb
, ⁵⁷
Co, ¹⁶⁷ Tm, ¹⁶⁶ Tm, ¹⁴⁶ Gd, ¹⁵⁷ Dy, ^95m Nb, ¹⁰³ Ru, ⁹⁷
Ru, ⁹⁹ Rh, ^101m Rh, and ²⁰¹ Tl. Chelating agents having catechol groups (formulas 9-12) are particularly suitable for use with radionuclides that have high mobility in vivo, especially iron radionuclides such as ⁵² Fe. Radionuclides that can be directly conjugated to antibodies include ²⁰³ Hg,
Contains ¹⁹⁷ Hg, ¹⁰⁵ Ag, ²⁰³ Pb, ⁹⁷ Ru, ¹⁰³ Ru, ⁹⁹ Rh, ^101m Rh and ⁴⁸ Cr. The most suitable radionuclides are those that have half-lives in the range of about 5 hours to 5 days and emit gamma-rays with energies in the range of 100 to 400 KeV. For reasons that cannot be clearly understood at this time, some individual monoclonal antibodies against tumor antigens resist direct metallization. Thus, incorporation of radionuclides by this route requires careful selection of specific antibodies. Therefore, it is currently preferred to attach a radionuclide to an antibody using a more flexible method of first attaching a chelating agent to the antibody and then forming a complex with the radionuclide. In this regard, ¹¹¹ In (T1/
2 = 2.8 days) as a chelating agent.
Preferably, it is combined with DTPA. The methods of the invention can be used to detect tumors generally using monoclonal antibodies directed against tumor-associated antigens. In addition to CEA, melanoma-associated antigen, alpha-feto-protein, ferritin,
Human choriogonadotropin, zinc glycinate conjugate, prostactic acid phosphatase (PAP)
can be used as an immunogen to stimulate the production of certain monoclonal antibodies, eg, as described above. In actual use, the labeled antibody in a suitable parenteral solution is injected into the patient. After sufficient time has elapsed, the patient is photo-scanned to identify the tumor and/or its metastases.
Detect any site with local radioactivity indicating the presence of a species. The following experiments performed with monoclonal antibodies against CEA labeled with ¹²⁵ I and ¹¹¹ In demonstrate that chelated radionuclides are more effective for tumor imaging according to the present invention compared to methods using iodine-labeled antibodies. has demonstrated the advantage of using monoclonal antibodies labeled with . 1. Preparation of Radiolabeled Anti-CEA Monoclonal anti-CEA available from Hybritech, Inc., (La Jolla, Ca.) was prepared by Bolton & Hunter.
It was labeled with ¹²⁵ I using the method of [Biochem.J., 133, 529-39 (1973)]. Sephadex G-
25 column, the final material contained less than 0.5% free iodine. Binding of radiolabeled monoclonal antibodies was greater than 80% for horse anti-mouse antibody conjugated to cepharose and greater than 75% for CEA conjugated to cepharose. Krejcarek & Tucker〔Biochemical and
Biophysical Research Communications, 77,
581 (1977)] using the complex DTPA as the chelating agent, the same monoclonal anti-CEA
was labeled with ¹¹¹ In. Sephadex G
Purified by passing through a -75 column. Antigen binding was comparable to that of ¹²⁵ I-labeled antibodies. The labeling step had no effect on the affinity constant Ka for the antibody compared to unlabeled antibody determined by titration with CEA. The in vitro stability of the labeled anti-CEA antibody was determined as follows. That is, a portion of the substance was kept constant at 37° C. for 72 hours in a parenteral solution containing sterilized standard saline (USP), and free radionuclides were measured by chromatography. antibody solution
Instilled on Baker alumina IB strips, 50%
Developed in aqueous acetone. Protein-bound radionuclides remain at the origin, while free radionuclides migrate. After the incubation period, the radioiodine-labeled material has a radioactivity of 3% due to the presence of free iodine.
showed less than Storage at 4°C reduced this by 50%. Under similar conditions, ¹¹¹ In anti-CEA showed comparable stability as well. 2 Distribution studies in nude mice Tissue distribution studies of radiolabeled monoclonal mouse anti-CEA were performed on nude mice bearing 0.5-1.0 g of human colon tumors. The weight of the mice ranged from 17 to 28 g (average about 23 g).
Tumors were generated by subcutaneous injection of mincemeat containing CEA-producing human colon adenocarcinoma cells. Distribution studies were carried out after 3 weeks. Two experiments were conducted. First, 19 animals were divided into four groups of 4 to 6 animals, and 125I anti-CEA antibody (approximately 0.3 μg antibody) was used.
0.1 ml of sterile standard saline (USP) solution containing 0.5 microcuries of 0.5 microcuries and carrier-free ⁶⁷ Ga citrate, a known non-specific human colon tumor contrast agent, was injected intravenously. Injections were performed without anesthesia using a 100 μl Hamilton syringe to ensure accuracy. Animals in which the dose partially penetrated the tail were excluded from this study. Following injection, mice were placed in sterile metabolic cages. The cage has a raised wire mesh floor to collect urine and feces. Sterilized 4×4 gauze was stuffed under this bed to prevent it from being chewed by animals.
4.4°C (40°C) with sterile food and water ad libitum
Mice housed in a clean room were killed in groups at 4, 24, 48 and 72 hours after tracer injection. Mice were anesthetized with ether and blood samples were obtained by direct cardiac puncture. Mice were then killed by cervical dislocation. During a series of dissections, the tumor, liver, kidney, muscle, heart, lungs, femur, and spleen were removed, washed twice in water and once in 10% formalin, wiped dry, and measured wet weight using an analytical balance. did. The intact stomach and intestinal tract were also removed and weighed. Blood, muscle, and bone account for 7%, 40%, and 10% of total body weight, respectively, for all organ uptake calculations.
It was estimated that %. Other organs were weighed as a whole. Radioactivity was run on an automated gamma well counter with a window operating over the 27-35 KeV photopeak of ¹²⁵ I and the 93 KeV photopeak of ⁶⁷ Ga. This counter should be run for 10 minutes or
It is programmed to exclude counts over 1 million. The inverse contribution of isotope radioactivity between window settings and correction for background were performed using prepared sources and by solving simultaneous equations. The radioactivity in the samples was then compared to a standard of injected material, and the results were expressed as % injected volume/g and % injected volume/organ. Tumor-to-tissue ratios were calculated from the data expressed as % dose/g. Radioactivity in organs, urine and feces was calculated as a percentage of the total injected volume. In the second study, 37 nude mice bearing tumors grown from the same human colon cancer were divided into five groups of seven to eight mice each. One group was used as a control;
One microcury of ¹²⁵ I human serum albumin (0.01 mg HSA) and three microcuries of carrier-free ¹¹¹ In citrate (0.01 mg citrate) were simultaneously injected IV and sacrificed 48 hours post-injection. The remaining four groups received ¹¹¹ In-labeled anti-CEA of 3 microcuries (1.5 μg antibody) and 5
Microcurie carrier-free ⁶⁷ Ga citrate was simultaneously injected. These four groups were sacrificed at 4, 24, 48 and 72 hours after injection, respectively. Tissue dissection, sample preparation for radiological assays, counting methods and calculations were performed as described above. For ¹¹¹ In, the spectrometer is
A 40KeV window (210-250KeV) was set to count the 247KeV photopeak, while
⁶⁷ Ga was counted using a 30KeV window that overlaps the 93KeV photopeak. Such a setting resulted in a negative contribution of radioactivity of less than 10%. Localized in the tumor as shown in Figure 1
¹¹¹ In anti-CEA concentration increased steadily throughout the experimental period. 23% of the injected dose was accumulated by 72 hours, a result suggesting that this concentration was even higher than if sampling was performed later. Conversely, the concentration in the blood decreased throughout the experimental period. The liver showed rapid uptake at 4 hours, followed by a period of little change before increasing up to 72 hours. Other tissues changed little over the period of the experiment. ^{The 67} Ga concentration in the tumor remained almost constant throughout the experiment and was about 1/4 of ^{the 111} In anti-CEA concentration after 72 hours. The ⁶⁷ Ga concentration in the blood decreased steadily, while the concentration in the liver showed a pattern somewhat similar to that of the ¹¹¹ In-labeled antibody. ⁶⁷ Ga in muscle
Concentrations decreased until 48 hours and then stabilized, while bone concentrations remained constant throughout the period. The amount of iodine in the tumor reaches its peak at 4 hours;
Initially it was somewhat greater than the amount of ¹¹¹ In, but decreased irregularly throughout the remainder of the experiment, and by 72 hours it was only 1/10 of the amount of ¹¹¹ In. At that time, the amount of ⁶⁷ Ga in the tumor was twice that of ¹²⁵ I. The count rate of ¹²⁵ I in all tissues decreases rapidly from its maximum value at 4 hours and in some cases reaches background levels by 48 hours. The excretion data (Figure 2) show a steady increase in urinary ¹¹¹ In between 24 and 72 hours, reaching a maximum value of 14% of the injected dose. ¹¹¹ In concentration in stool is 24 and
It remained approximately constant at 48 hours and then increased to 17% at 72 hours. On the other hand, the amount in the intestinal tract remained relatively constant during the entire experimental period, with 5% of the dose
It never exceeded. ^{The 67} Ga excretion pattern is somewhat similar to that of ¹¹¹ In, but (at 72 hours) the amount of tracer is greater in the intestinal tract and in the stool than that observed for ¹¹¹ In, and the opposite is true in the urine. It was low. Approximately 60% of ^{the 125} I radioactivity was excreted in the urine within the first 24 hours, and 75% by 48 hours. The other 5% of ¹²⁵ I was contained in the stool. Thus,
Approximately 80% of the originally injected ¹²⁵ I was excreted from the animals after 72 hours. Chromatography of ¹²⁵ I in urine showed that most of it was free iodine, including a second species, likely free ¹²⁵ I complexed with something other than protein. Figure 3 shows data for ¹¹¹ In labeled anti-CEA compared to ¹¹¹ In citrate and ¹²⁵ I HSA at 48 hours. ¹¹¹ In citrate was used as a control for any indium that might be degraded from the antibody, while ¹²⁵ I HSA was used as a control for non-specific proteins. ¹¹¹ In anti-CEA showed a markedly different distribution pattern than ¹¹¹ In citrate and was concentrated in tumors with a 10-fold higher efficiency. The uptake of these two tracers by other tissues was also quite different. The concentration of ¹²⁵ I HSA on the tumor is 20% of ¹¹¹ In anti-CEA, but still more than 50% greater than ¹²⁵ I anti-CEA. The distribution of ¹²⁵ I HSA in non-tumor tissue is also markedly different from that of the ¹¹¹ In anti-CEA product. ^125I HSA (long considered to be a stable iodinated protein) has been shown to be almost 60% excreted (43% in the urine) by 48 hours, and ^125I anti-CEA is also excreted in the urine. This was almost consistent with the above finding that it was found in The fraction in the urine is probably free iodine. Tumor/histology (Figure 4) shows that ¹¹¹ In anti-CEA is superior to ¹⁷ Ga for all tissues except blood, which is almost the same as ⁶⁷ Ga. In some organizations, the apparent
Although considered preferable to ¹¹¹ In and ⁶⁷ Ga, ^{the 125} I anti-CEA ratio is misleading. This is because the high ratio for ¹²⁵ I anti-CEA is not due to high localization in tumors, but rather to low ¹²⁵ I concentrations in normal tissues. From the above experiments, ¹²⁵ I anti-CEA is clearly unsuitable as a tumor localization agent. Rapid and high dehalogenation reduces tumor tracer concentrations and increases the blood background, limiting its use in imaging without skilled subtraction techniques. In fact, in 72 hours, tumors ^absorb an amount of non-specific ⁶⁷ Ga on a gram-per-gram basis.
Contains twice as much. Furthermore, the tumor/blood ratio is better with ⁶⁷ Ga than with iodinated antibodies. If the use of ⁶⁷ Ga is considered insufficient for radiocarcinoma imaging of the colon, Mach et al. [N.Eng.J.Med.,
303, 5-10 (1980)] are easily explained. These data using ¹²⁵ I clearly demonstrate that: That is, when using ¹³¹ I and there is no subtraction technique,
Extremely large amounts of ¹³¹ I-labeled material must be administered to achieve the necessary concentration on the tumor for effective imaging. This results in extremely high radiation doses to the patient based on the β-component of 608 KeV of ¹³¹ I with a physical half-life of 8 days. Conversely, a larger proportion of the injected amount of ¹¹¹ In anti-CEA taken up by the tumor as well as more favorable physical properties of ¹¹¹ In allows for the injection of smaller amounts of radiopharmaceutical,
On the other hand, contrast enhancement is improved and radiation dose to the patient is minimized. The tumor-to-background ratio produced by ¹¹¹ In anti-CEA is well within the range required for imaging purposes. This is because large amounts of radionuclides are localized within the tumor. Furthermore, this data suggests that tumors may take up radiolabels that have been taken up or attached to other tissues. Each mouse received 4 days after injection of ¹¹¹ In-labeled anti-CEA.
At 24, 48 and 72 hours, phogam HP
It was subjected to optical scanning using an Anger gamma camera. By 48 hours, the tumor was well imaged without the need to resort to subtraction techniques. In 72 hours,
The contrast power of the tumor was further enhanced. The in vivo stability of directly labeled monoclonal antibodies and the resulting stability for use in tumor imaging was demonstrated using monoclonal anti-melanoma labeled with ¹⁰³ Ru and with the same antibody labeled with ¹²⁵ I. This is proven by the following comparative experiments. 1 Preparation of ¹⁰³ Ru Labeled Anti-Melanoma 220 μl of an aqueous solution of ¹⁰³ RuCl ₃ (obtained from New England Nuclear Inc.) was dissolved in saturated potassium acetate solution.
Added to 100 μl. The PH was adjusted to 5.3 with 70 μl of 10M NaOH. This radionuclide solution was added to the mouse anti-
500 μl of a 0.5 μg/μl solution of melanoma antibody was added and the mixture was incubated at room temperature for 1 hour. PH
Adjusted to 7.2 by adding 20 μl of 10M NaOH and the formulation was stored at room temperature overnight. Unbound metals were separated from antibody-bound metals by passing the reaction mixture through a Sephadex G-50 column and eluting with phosphate buffered saline at pH 7.2. Protein-containing fractions were collected and pooled for in vivo testing in mice. 2 Distribution study in normal mice The study of distribution in tissues was performed on normal BALB-C mice prepared according to the above method.
125 I-labeled anti- ¹²⁵ prepared using the same method described above to label ¹⁰³ Ru tissue anti-melanoma and anti-CEA.
Melanoma was used. Mice were divided into two groups and labeled with ¹²⁵ I and ¹⁰³ Ru, respectively.
Injected intravenously with labeled antibody. Mouse 4, 24,
After 48, 72 and 96 hours, animals were sacrificed and dissected as described above for monoclonal anti-CEA studies.
The radioactivity of the organs was measured. The distribution of ¹²⁵ I and ¹⁰³ Ru in the tissue is shown in the table below.

Table: The data in the table show that ¹²⁵ I-labeled anti-melanoma was rapidly dehalogenated, just as happened with ¹²⁵ I-labeled anti-CEA, whereas ¹⁰³ Ru-labeled anti-melanoma was stable. It is shown that. These observations are confirmed by the following facts. That is, in the blood
^{The 125} I concentration is extremely high 4 hours after injection and drops to a low value, but remains at a constant level from 24 to 96 hours. Conversely, ¹⁰³ Ru concentrations are relatively rapidly lost from the blood and concentrated in the liver, as expected in non-tumor-affected hosts. Concentrations in the spleen and kidney for mice injected with ¹⁰³ Ru-labeled anti-melanoma are also consistent with in vivo stability. It is known that CEA as well as several other tumor-associated antigens are secreted or released by tumors. In such cases, the generation of background radiation due to the binding of labeled antibodies to antigens circulating in the blood or other tissues can be avoided by first administering unlabeled antibodies and allowing them to bind to the circulating antigens. can be reduced. This will also tend to reduce the high hepatic uptake of labeled antibodies. After an appropriate period of time, a labeled antibody is added and the object is optically scanned to determine the site of localized radioactivity. Although the above discussion has emphasized the use of a single monoclonal antibody labeled with a radionuclide, it is also within the scope of this invention to use two or more labeled monoclonal antibodies directed against different antigenic determinants. There is. The different antibodies are chosen so as not to interfere with the binding of other antibodies to the antigen. By using multiple non-interfering labeled antibodies, tumor imaging power is enhanced. This is because the antigen will have a high capacity for labeled antibodies. The use of multiple antibodies is particularly useful for imaging tumors where tumor-associated antigens are present at low concentrations. It is to be understood that the foregoing description of the invention is of presently preferred embodiments and that other variations will be apparent to those skilled in the art. Accordingly, the scope of the invention is to be limited only by the claims.

[Brief explanation of drawings]

Figure 1 shows the time after injection of anti-CEA and ⁶⁷ Ga citrate labeled with ¹¹¹ In and ¹²⁵ I into nude mice infected with human colon cancer, and the changes in tissue levels.
12 is a graph showing a comparison of the distributions of ¹¹¹ In and ¹²⁵ I and the distribution of ⁶⁷ Ga. Figure 2 shows the amount of ¹¹¹ In and ¹²⁵ I excreted from nude mice over time after injection of ¹¹¹ In and ¹²⁵ I-labeled anti-CEA and ⁶⁷ Ga citrate.
and ⁶⁷ Ga. Figure 3 shows that ¹¹¹ In ^{and 125} I-labeled anti-CEA and ¹¹¹ In citrate and ¹²⁵ I ^- labeled human albumin were injected into nude mice for 48 hours.
It is a graph showing a comparison of the tissue distribution of. Figure ^{4 shows that 111 In} and ¹²⁵ I tumors/
FIG. 7 is a graph showing the tissue ratio compared to ⁶⁷ Ga as a function of time.

Claims (1)

[Scope of Claims] 1. A monoclonal antibody against a tumor-associated antigen in which a metal radionuclide is bound via a chelating agent bound to the monoclonal antibody, wherein the chelating agent is a polyaminocarboxylic acid; Monoclonal antibodies whose tumor-associated antigen is carcinoembryonic antigen. 2. The monoclonal antibody according to claim 1, wherein the chelating agent is a polyaminocarboxylic acid represented by the following formula. In the formula, x is 0 or an integer, y is 1 or 2, z
is an integer from 1 to 7, R is hydrogen, or a group that binds the chelating agent to the antibody, or a group that affects the binding constant of the radionuclide chelating agent. 3 R is hydrogen, methyl, -CH ₂ C ₆ H ₄ OCH ₂ CO ₂
H, and -C ₆ H ₄ -A [A is a diazonium salt or a precursor thereof, or [Formula] (a group substituted upon bonding with L). ] The monoclonal antibody according to claim 2, which is selected from the following. 4. The monoclonal antibody according to claim 3, wherein x is 0 and R is [Formula]. 5. The monoclonal antibody according to claim 3, wherein x is 1 and R is [Formula]. 6 The chelating agent is ethylenediaminetetraacetic acid,
p-bromoacetamidodiphenyl (ethylenedinitrilotetraacetic acid), 1-(p-aminophenyl)-
The monoclonal antibody according to claim 1, which is selected from the group consisting of ethylenediaminotetraacetic acid and diethylenetriaminepentaacetic acid. 7 The radionuclide is a gamma ray emitter with a half-life of 5 hours to 5 days, and the energy of the gamma ray emission is 100 to 5 days.
The monoclonal antibody according to any one of claims 1 to 6, which has a voltage of 400 KeV. 8 Radionuclides are ^195m Pt, ⁵⁷ Ni, ⁵⁷ Co, ¹⁰⁵ Ag, ⁶⁷ Cu,
⁵² Mn, ⁵² Fe, ¹¹¹ In, ¹¹³ In, ^99m Tc, ⁶⁷ Ga, ⁶⁸ Ga, ¹⁶⁹ Yb
，
¹⁶⁶ Tm, ¹⁶⁷ Tm, ¹⁴⁶ Gd, ¹⁵⁷ Dy, ^95m Nb, ¹⁰³ Ru, ⁹⁷ Ru, ^9
9 Ru, ^101m Rh, ²⁰¹ Tl, ²⁰³ Hg, ¹⁹⁹ Hg, ¹⁰⁵ Ag, ²⁰³ Pb, ^9
9
Claim 1 selected from Rh and ⁴⁵ Cr
7. The monoclonal antibody according to any one of items 7 to 7. 9. A monoclonal antibody against a tumor-associated antigen in which a metal radionuclide is bound via a chelating agent bound to the monoclonal antibody, wherein the chelating agent is a polyaminocarboxylic acid, and the tumor-associated antigen is A contrast agent for tumors whose active ingredient is a monoclonal antibody that is a carcinoembryonic antigen. 10. The contrast agent according to claim 9, which is in the form of a solution for parenteral administration.