MONOCLONAL ANTIBODY USEFUL IN THE DIAGNOSIS OF HUMAN STOMACH OR BREAST CANCER

Abstract: A monoclonal antibody of the IgM class which is useful for the diagnosis of human stomach or breast cancers and which reacts with a glycoprotein antigen having a molecular weight by gel filtration of 1,000,000 or higher, the antigenic determinant recognized being a sugar chain with a sialic acid residue at an end thereof, has the following characteris­ tics: (1) a reactivity with human cancers of the stomach, large intestine, pancreas, breast, lung, biliary duct, uterus and oesophagus; (2) a reactivity with normal human sub­ maxillary gland, proximal renal tubule, bronchial gland, squamous epithelial corneum, pancreatic Langerhans' is­ lands, liver cell membrane and duodenal gland; (3) a reac­ tivity with human intestinal metaplastic gastric mucosa; and (4) a non-reactivity with normal human prostate gland, bili­ ary duct and pancreatic duct. The monoclonal antibody can be produced by administering or implanting cancer cells or tissue into an animal having no thymus, allowing the cells or tissue to propagate in the animal, administering T cells or both T cells and B cells to the animal, taking antibodyproduc­ ing B cells from the animal, fusing the B cells with myeloma cells, selecting fused cells producing an antibody against the cancer cells or tissue, cloning the fused cells and culturing the cloned cells.

Description: This invention relates to a method for the production of a monoclonal antibody, more especially a monoclonal antibody specific for certain cancers. Production of monoclonal antibodies by cell fusion techniques is established, and many workers have attempted and are still attempting to produce new monoclonal antibodies which recognize cancer-related antigens and are useful for diagnosis and/or treatment of cancers. Among monoclonal antibodies reported up to now, the monoclonal antibody developed by H. Koprowski et al ., CA19-9 (1116NS19-9) is at present expected to be of practical use in the serum diagnosis of pancreatic cancer. However, it is insufficiently effective for the diagnosis of other cancers including gastric cancer. Generally, the production of monoclonal antibodies recognizing cancer-related antigens has hitherto been performed by administering cancer cells to an animal which has a thymus, for example a mouse or rat, in other words animal which has both B cells and T cells, to immunize the animal with the cancer cells, fusing antibody-producing cells obtained from the immunized animal with myeloma cells, selecting fused cells producing a desired antibody, cloning the fused cells, and culturing the cloned fused cells. Other methods are not available and have not been reported. The present inventors have studied monoclonal antibodies and new methods for production thereof. They have found a method for the production of monoclonal antibodies which is quite different from conventional methods, which is capable of producing a monoclonal antibody which reacts highly efficiently with various cancers including gastric cancer. The present invention provides a method for the production of a monoclonal antibody, which method comprises administering or implanting cancer cells or cancer tissue into an animal having no thymus, allowing the cancer cells or cancer tissue to propagate in the animal, administering T cells or both T cells and B cells to the animal, taking antibody-producing B cells from the animal, fusing the B cells with myeloma cells, selecting fused cells producing an antibody against the cancer cells or cancer tissue, cloning the fused cells and culturing the cloned cell. The method of the present invention is capable of producing a monoclonal antibody of the IgM class having a κ chain as the L-chain, which antibody reacts with a glycoprotein antigen having a molecular weight of 1,000,000 or higher as determined by gel filtration, the antigenic determinant recognized being a sugar chain with a sialic acid residue at an end thereof, said monoclonal antibody having the following properties: (1) a reactivity with human cancers of the stomach, large intestine, pancreas, breast, lung, biliary duct, uterus and oesophagus; (2) a reactivity with normal human tissues of the submaxillary gland, proximal renal tubule, bronchial gland, squamous epithelial corneum, pancreatic Langerhans' islands, liver cell membranae and duodenal gland; (3) a reactivity with human intestinal metaplastic gastric mucosa; and (4) a non-reactivity with normal human tissues of the prostate gland, biliary duct and pancreatic duct. Cells and tissues which are employed for selecting fused cells producing the monoclonal antibody and for investigating the reactivity of the monoclonal antibody are human-derived in the invention. It has been reported that the antigenic determinant recognized by the abovesaid monoclonal antibody CA19-9 is sialylated-Lewis a . The monoclonal antibody which can be produced by the method of the present invention also recognizes an antigenic determinant which is a sugar chain having a sialic acid residue at an end thereof. However, comparative immunostaining tests of specimens of the same origin with both monoclonal antibodies showed that some specimens readily reacted with the above antibody but not with CA19-9, while other specimens reacted reversely. Furthermore, it has been found that the monoclonal antibody which can be produced by the method of the present invention reacts with the liver cell membrane, proximal renal tubule of the kidney, pancreatic Langerhans' cells and squamous epithelial corneum, while CA19-9 does not, in comparative experiments of the reactivities of both antibodies against normal human tissues. In addition, CA19-9 reacts with the prostate gland, biliary duct and pancreatic duct while the above monoclonal antibody does not. Thus, each antibody recognizes a different determinant. As shown in Examples hereinafter, the above monoclonal antibody reacts with gastric cancer, colonic cancer, pancreatic cancer, breast cancer, lung cancer, cholangiocarcinoma, uterine cancer and esophageal cancer. The above monoclonal antibody also reacts with normal tissues of the submaxillary gland, proximal renal tubule, bronchial gland, squamous epithelial corneum, pancreatic Langerhans' islands, liver cell membrane and duodenal gland. Furthermore, the above monoclonal antibody reacts with the intestinal metaplastic gastric mucosa. However, the above monoclonal antibody does not react with normal tissues of the prostate gland, biliary duct and pancreatic duct. When a tissue specimen of gastric cancer was treated with neuraminidase, which is the enzyme that cleaves sialic acid residues, the above monoclonal antibody did not show reactivity against the a treated tissue specimen. This indicates that there is a sialic acid residue present in the antigenic site (determinant) recognized by the above monoclonal antibody. On the other hand, the above monoclonal antibody did not react against a tissue specimen of gastric cancer which had been treated with periodic acid, indicating that the determinant recognized by the antibody is a sugar chain. The antigen with which the above monoclonal antibody reacts has a molecular weight of 1,000,000 or higher as determined by gel filtration. In addition, the antigen has an ability to incorporate glucosamine thereinto and, accordingly, is a glycoprotein. Thus, the antigen with which the above monoclonal antibody reacts is a glycoprotein having a molecular weight of 1,000,000 or higher as determined by gel filtration the determinant being recognized by the monoclonal antibody being a sugar chain having a sialic acid residue at an end thereof. The above monoclonal antibody belongs to the immunoglobulin class IgM having a κ chain as L-chain. The antigen with which the above monoclonal antibody reacts is often found in a large amount in sera of patients suffering from, for example, gastric cancer, breast cancer, colonic cancer and pancreatic cancer, as well as in the cancer tissues. Accordingly, the above monoclonal antibody is useful, in particular, for a highly efficient serum diagnosis of gastric cancer and breast cancer. The antigen with which the above monoclonal antibody reacts is also found in the sera of a patient suffering from a cancer as well as in the cancer tissues. Accordingly, the monoclonal antibody can be useful for the serum diagnosis of a patient suffering from, for example, gastric cancer or breast cancer. When the antigen recognized by the above monoclonal antibody appears abundantly in the serum of a patient, the monoclonal antibody can be used for the determination of the effect of treatment or the prediction of recurrence. The above monoclonal antibody can be used for the diagnosis of cancer localization by incorporation of a radioactive isotope. Also, a combination of the above monoclonal antibody with an anti-cancer agent can be utilized in "missile therapy". The above monoclonal antibody may be helpful for the accurate diagnosis of some lesions which are difficult to differentiate from cancers histologically. Animals having no thymus include, for example, nude mice nu/nu and nude rats rnu/rnu, which can be used in the method of the present invention but any animal except humans which have no thymus nor a substantial amount of T cells can be utilized. A mouse having no thymus is advantageously employed. Such an animal having no thymus cannot substantially produce an antibody against a foreign implant in spite of B cells being present in its body, since no substantial amount of T cells is produced in the body. When cancer cells or cancer tissue is administered or implanted in such an animal having no thymus, the cancer cell or cancer tissue may propagate (grow) in the animal. Cancer cells or tissues which may be used for the method include human or any other animal's cancer cells or cancer tissues. Examples of cancers are gastric cancer, lung cancer, breast cancer, pancreatic cancer, colonic cancer, uterine cancer, esophageal cancer, kidney cancer, rectum cancer, cholangiocarcinoma and thyroid cancer, but the invention is not limited to these. The amount of cancer cells or cancer tissues administered or implanted is not specifically limited. Usually, it is preferred to implant one to several pieces of cancer tissues minced into pieces about 1 to 4 square mm in size. More specimens may be implanted. The implantation site is preferably subcutaneous or intraperitoneal. When cancer cells are used, the amount administered is preferably from 10⁵ to 10⁸ cancer cells. After administering or implanting cancer cells or cancer tissues, the cancer cells or cancer tissues propagate and a mass of tumor grows as the animal is fed. For example, when cancer tissues of 1 to 4 square mm are implanted subcutaneously to a mouse having no thymus, a tumor mass of about 1 cm in the largest diameter grows in one to a few months. When the tumor has grown to, for example, about 5 mm to 5 cm in the largest diameter, T cells or both T and B cells are administered to the thymus-deficient mouse having the tumor. The lymphocytes administered are preferably derived from an animal of the same species as the thymus-deficient animal. The amount of the lymphocytes administered is preferably from 0.1 to 5 times the amount of T cells or T and B cells contained in the spleen of one animal of the same species which has a thymus and is accordingly capable of producing antibodies. One administration of the lymphocytes is sufficient for the purpose of this method and there is no necessity to administer them several times. When administered, the T cells will permit either B cells already present in the animal incapable of producing any antibody or the B cells administered to produce antibodies against the tumor (cancer) in the animal. After administration of the lymphocytes, the tumor mass will gradually reduce or disappear. At the time when the mass is reduced to a half or smaller in size or disappears, the spleen containing antibody-producing cells is removed from the animal and the spleen cells are hybridized with myeloma cells. These antibody-producing cells are B cells, which circulate in the living body and accumulate in the spleen or other organs. Although B cells are preferably derived from the spleen, any site wherein B cells are present in a large amount may be utilized. Hybridization, subsequent selection of hybridomas, culture of hybridomas, and collection of the monoclonal antibodies in the method of the invention may be carried out in the same manner as above-described for the conventional method. In the method of the invention several or many administrations of cancer cells to animals, which is absolutely necessary in the conventional method, is not required. Thus, a simpler method is provided according to the invention. The method of the invention utilizes animals in which cancer cells or tissues have already been grown and, therefore, a large amount of cancer cells is present. Accordingly, B cells which produce the antibodies recognizing cancer-related antigens are produced in a large amount. Furthermore, the selection of desired hybridomas is carried out with high efficiency. The invention is further described in the following Examples. EXAMPLE 1 (1) Production of Monoclonal Antibody: Human poorly differentiated adenocarcinoma of the stomach was obtained from a nude mouse to which the carcinoma had been implanted (St-4) and was minced into specimens of 2 to 3 mm in size. The specimens were implanted subcutaneously into BALB/c nu/nu mice which are thymus-deficient having almost no T cells. After about one and a half months the tumor had grown to 10 mm in the maximum diameter. The spleen removed from a BALB/c nu/+ nude mouse was minced, passed through a stainless mesh and suspended in 0.5 ml of saline. The resulting suspension containing T and B cells was intraperitoneally administered to the above BALB/c nu/nu mice carrying the tumor. The tumor disappeared one month after administration of the lymphocytes. Then, 0.2 ml of homogenates of St-4 was administered intraperitoneally to each BALB/c nu/nu mouse. (This administration is not necessarily carried out in the method of the invention.) Three days later, the spleen was removed from the mouse. Cell fusion was accomplished accoridng to the method described by Watanabe et al . in Men-eki Jikken Sosaho (in Japanese) VII, 2963-2967 (1978): The removed spleen was minced, passed through a stainless mesh, and centrifuged at 1,500 rpm, 200 G. After 50 ml of 0.7% NH₄Cl was added to the obtained precipitate to eliminate red cells, the precipitate was washed twice with RPMI-1640. To 1 x 10⁸ spleen cells thus obtained, 2 x 10⁷ (5:1) of mouse myeloma cells, P3-X63-Ag8-U1 (hereinafter referred to as P3U1), which had been washed twice with RPMI-1640, were mixed, and the mixture was centrifuged at 2,000 rpm, 200 G for 10 minutes. After dividing well the precipitated cells, 1 ml of RPMI-1640, 37°C, pH 7.4, containing 45 % (W/V) of polyethylene glycol 4,000 (Merck & Co., Inc.) was added and the mixture incubated at 37°C for 8 minutes. After reation for one minute RPMI-1640 was gradually added to provide a final volume of 40 ml at the end of the hybridization, and the mixture was centrifuged at 1,000 rpm, 100 G. To the precipitated cells there was added 40 ml of RPMI-1640 containing 10% fetal bovine serum, and the resulting cell suspension was cultured at 37°C in a culture vessel filled with 5% CO₂. After 24 hours, the medium was replaced by HAT medium, which contained hypoxanthine, aminopterin, thymidine and 10% fetal bovine serum, and the culture was distributed into a Costar micro culture plate in an amount of 0.2 ml per well. On the 10th day, the supernatant was collected and analyzed for antibody production using the staining by enzyme-labeled antibody technique of paraffin pieces to which gastric cancer tissues were fixed with formalin. Hybridomas in the wells positive in production of antibody reactive with the cancer were cloned by limiting dilution to 0.6 cells per well. The initial medium used was HT medium containing hypoxanthine, thymidine and 10% fetal bovine serum to which 5 x 10⁵ thymus cells per well of BALB/c nu/+ mouse were added as a feeder layer. The initial medium was later replaced by RPMI-1640 medium containing 10% fetal bovine serum. Cloning by limiting dilution was repeated once again. For mass culture, hybridomas in one well were increased to 5 wells, 24 wells (Falcon 3008) and finally a Falcon tissue culture flask. The obtained supernatant to which 0.1% of NaN₃ had been added was stored at 4°C. (2) Selection of Monoclonal Antibody and Staining of Various Tissues by the Monoclonal Antibody: Staining of some tissues for the selection of the hybridomas producing the monoclonal antibody and staining of various tissues for the analysis of the monoclonal antibody was accomplished according to the avidin-biotin-peroxidase complex method described by S. M. Hsu et al . in J. Histochem. Cytochem., 29 , 577-580 (1981) using paraffin pieces to which the tissues were fixed with formalin: Specimens of sliced human gastric cancer tissues, other human cancer tissues and normal human tissues fixed by 10% formalin to and embedded in paraffin, which were widely available, were treated with methanol containing 0.3% H₂O₂ for 20 minutes after the paraffin was removed. The specimens were then washed with phosphate buffered saline (PBS), and treated with PBS containing 10% normal swine serum for 30 minutes. The specimens were reacted with a solution containing the antibody, that is, the supernatant which had been obtained in (1) above and diluted tenfold with PBS, about 1 µg/ml, at room temperature for 2 hours, and further reacted at 4°C overnight. The reaction mixture was washed with PBS for 15 minutes and treated with biotin-bound anti-mouse immunoglobulin, 7.5 µg/ml, for 30 minutes. The sections were washed with PBS for 15 minutes and then treated with avidin DH-biotin-peroxidase complex at room temperature for 30 minutes. The sections were then washed with PBS for 15 minutes and reacted with a diaminobenzidine solution containing 50 mg diaminobenzidine, 0.006% H₂O₂, Tris buffer, pH 7.6, for 5 to 10 minutes. The cellular nuclei were stained with hematoxylin, mounted in a usual manner and analyzed by microscopy. (3) Results: Reactivities of the antibodies produced in 78 wells among 400 wells were analyzed and one hybridoma was selected which produced the monoclonal antibody reacting with gastric cancer, colonic cancer, pancreatic cancer, breast cancer, lung cancer, cholangiocarcinoma, uterine cancer and esophageal cancer, and the normal submaxillary gland, proximal renal tubule, bronchial gland, squamous epithelial crneum, pancreatic Langerhans' islands, liver cell membrane and duodenal gland, as well as the intestinal metaplastic gastric mucosa, but not reacting with the normal prostate gland, biliary duct and pancreatic duct. Reactivities of the monoclonal antibody which was produced by the hybridoma selected, NCC-St-4 39, with various cancer or normal tissues were analyzed according to the method described in (2) above. (A) Table 1 shows the results of the reactivity tests of the monoclonal antibody against various cancer tissues. Reactivities with Cancer Tissues cancer tissue positive specimen positive to total specimen % of positive specimen ++a) +b) gastric cancer 33 29 62/102 60.7 colonic cancer 17 9 26/26 100 pancreatic cancer 21 7 28/28 100 lung adenocarcinoma 11 5 16/17 94.1 lung squamous cell carcinoma 6 8 14/19 73.7 lung large cell carcinoma 7 3 10/18 55.6 lung small cell carcinoma 0 4 4/19 21.1 breast cancer 15 7 22/27 81.5 a) ++: a third or more of the cancer cells being positive b) +: less than a third of the cancer cells being positive As shown in Table 1, 100% of colonic cancer and pancreatic cancer, 60.7% of gastric cancer, 81.5% of breast cancer and lung cancer and in particular, 94.1% of adenocarcinoma reacted with the monoclonal antibody. The reactions of the monoclonal antibody were often strong with mucus and cell membrane in the positive specimens of adenocarcinoma. In the squamous cell carcinoma, only the keratotic area reacted strongly. Furthermore, the reactions were positive with the one cholangiocarcinoma specimen tested, two uterine cancer specimens among three tested, the one esophageal cancer specimen tested and one kidney cancer specimen among two tested. (B) Table 2 shows the results of the reactivity tests of the monoclonal antibody against various normal tissues. The monoclonal antibody also reacted with 11 intestinal metaplastic gastric mucosa specimens among 25 specimens tested. EXAMPLE 2 The gastric cancer specimen was treated with 0.2 U/ml of neuraminidase at 37°C for 2 hours prior to the staining by the avidin-biotin-peroxidase complex method in Example 1 (2). Another gastric cancer specimen was treated with 0.5% periodic acid at 37°C for one hour. Both treated specimens were tested for reactivities in the same manner as in Example 1. No staining was observed. These results demonstrate that the site (determinant) recognized by the monoclonal antibody is a sugar chain having a sialic acid residue at an end thereof. EXAMPLE 3 In order to determine the immunoglobulin class of the monoclonal antibody precipitation reactions of the monoclonal antibody with anti-mouse sera of various Igs were carried out in agar gel. Clear precipitation curves were formed in the reactions of the monoclonal antibody with anti-mouse IgM serum and with anti-mouse κ chain serum, but no reactions occurred with sera of IgG, IgA, IgD, IgE and λ chain. Thus, the monoclonal antibody is an immunoglobulin IgM, κ. EXAMPLE 4 (1) The hybridomas obtained in Example 1 (1 x 10⁷ cells) were administered intraperitoneally to BALB/c nu/+ mice which had been treated with pristan. One week later, about 5 ml of ascites were collected and subjected to gel filtration by Sepharose CL-6B. Fractions reacting with IgM were selected in the same manner as Example 3 by Ouchterlony's method. The purified antibodies were labeled with biotin according to the method described by Guesdon et al . in J. Histochem. Cytochem., 27 , 1131-1139 (1979). (2) After gel filtration of 5 ml serum from a patient suffering from pancreatic cancer in Sepharose CL-6B column, each fraction was distributed in a 96 well micro titer plate in an amount of 0.1 ml per well. After 24 hours, each well was blocked with PBS containing 5% bovine serum albumin. The biotin-labeled antibodies (5 µg/ml) obtained in (1) above were added to the plate and the avidin-biotin-peroxidase complex method was carried out. The reaction was performed by adding 0.015% H₂O₂ to 0.1 M citrate buffer, pH 4.5, containing 1 mg/ml of orthophenylenediamine. Measurements were done by utilizing Dynatech Autoreader, MR580, with O.D. 450. The antigen recognized by the monoclonal antibody was detected near the void volume, V₀, with their molecular weight being 10⁶ daltons or higher. EXAMPLE 5 To a culture medium of KATO III, siglet-ring cell carcinoma of stomach, H³-glucosamine was added in a concentration of 15 µCi/ml. After three days culture, the supernatant was recovered and dialyzed to eliminate free H³-glucosamine. The supernatant was passed in an affinity column coupled with the monoclonal antibody. The antigen having H³ radioactivity was adsorbed on the column. These results show that the antigen with which the monoclonal antibody reacts is a glycoprotein. EXAMPLE 6 In order to measure the reactions of the monoclonal antibody with sera of normal men, patients with benign diseases and patients with various cancers, enzyme immunoassay (inhibition EIA) was performed according to the method described in Proc. Natl. Acad. Sci., USA, Vol. 81, pp.5242-5246, August 1984, "Detection of a pancreatic cancer-associated antigen (DU-PAN-2 antigen) in serum and ascites of patients with adenocarcinoma". Fifty specimens of normal men were measured and the value of the mean thereof plus a value twice larger than the standard deviation was chosen as a cutoff value. The results are shown in Table 3. Reactivities against Various Sera Sera Positive/Total Specimen normal 1/50 benign diseases of stomach 1/37 benign diseases of pancreas 0/11 benign diseases of liver 0/31 gastric cancer 18/28 breast cancer 14/24 pancreatic cancer 8/22 colonic cancer 6/28 lung cancer 4/17 uterine cancer 5/16

Claims: A method for the production of a monoclonal antibody, which method comprises administering or implanting cancer cells or cancer tissue into an animal having no thymus, allowing the cancer cells or cancer tissue to propagate in the animal, administering T cells or both T cells and B cells to the animal, taking antibody-producing B cells from the animal, fusing the B cells with myeloma cells, selecting fused cells producing an antibody against the cancer cells or cancer tissue, cloning the fused cells and culturing the cloned cells. A method according to claim 1, wherein the animal having no thymus is a mouse and the myeloma cells are derived from a mouse. A method according to claim 1, wherein the animal having no thymus is a nude mouse and the myeloma cells are of the cell line P3-X63-Ag8-U1. A method according to any one of claims 1 to 3, wherein the cancer cells or cancer tissue is human-derived. A method of any one of claims 1 to 4, wherein the monoclonal antibody that is produced is a monoclonal antibody of the IgM class having a κ chain as the L-chain, which antibody reacts with a glycoprotein antigen having a molecular weight of 1,000,000 or higher as determined by gel filtration, the antigenic determinant recognized being a sugar chain with a sialic acid residue at an end thereof, said monoclonal antibody having the following properties: (1) A reactivity with human cancers of the stomach, large intestine, pancreas, breast, lung, biliary duct, uterus and oesophagus; (2) a reactivity with normal human tissues of the submaxillary gland, proximal renal tubule, bronchial gland, squamous epithelial corneum, pancreatic Langerhans' islands, liver cell membranae and duodenal gland; (3) a reactivity with human intestinal metaplastic gastric mucosa; and (4) a non-reactivity with normal human tissues of the prostate gland, biliary duct and pancreatic duct. A method according to any one of claims 1 to 5, which further comprises contacting the antibody produced with the serum of a patient under test in order to diagnose human stomach or breast cancer.

Inventors: HIROHASHI, SETSUO, SHIMOSATO, YUKIO, WATANABE, MASAHIKO
Applicants: HIROHASHI, SETSUO, NIPPON KAYAKU KABUSHIKI KAISHA, SHIMOSATO, YUKIO, WATANABE, MASAHIKO
Application year: 1985
Main classification: C12P21
IPC codes: C07K16, C12P21