RADIOIMMUNO DETECTION OF HUMAN CANCERS USING ANTITUMOR MONOCLONAL ANTIBODY

Abstract: Radioimmuno detection of cancers by detecting tumor associated antigens comprising the following steps: (i) preparing samples of hybridoma XMMCO791 as herein described, (ii) separating and purifying the associated antibody produced by XMMCO791 hybridomas to obtain the IgG2b isotype, (iii) labelling the antibody thus obtained with a radioactive label, (iv) preparing composition containing an effective concentration of said labelled antibody, (v) administering said antibody composition to a patient and (vi) thereafter screening said patient to detect concentrations of radioactivity thereby indicating a concentration of antibody.

Description: RADIOIMMU O DETECTION OF HUMAN CANCERS USING ANTITUMOR MONOCLONAL ANTIBODY DESCRIPTION The present invention relates to the radioimrauno detection of human cancers by antigens monoclonal antibodies. It is well known that radioactively labelled antibodies directed against tumor associated antitumors can detect cancer deposits within the body. The present invention relates to a specific monoclonal antibody which reacts with human malignant colorectal cells which antibody has been labelled with radio active material. The method of the invention has been found to provide a fascile means of diagnosing with precision the presence and position of a cancer deposit particularly in the colorectal region. According to the present invention there is provided a method of detecting tumor associated antigens which method comprises:- 1. preparing samples of hybridoma XMMC0791 as herein described. 2. separating and purifying the associated antibody produced by XMMCO-791 hybridomas to obtain the IgG2b isotype. 3. labelling the antibody thus obtained with the radio active label. 4. preparing a composition containing an effective concentration of said labelled antibody. 5. administering said antibody composition to a patient, 6. thereafter screening said patient to detect concentrations of radioactivity thereby indicating a concentration of antibody and presence of a cancer deposit. The antibodies are preferably labelled with iodine 131. The screening maybe carried out using a gamma camera. The image obtained using a gamma camera may be enhanced using an image enhancement technique which may further include blood cell and blood transferring labelling using isotopes selected from at least one of the group consisting of 99m Tc and 113m In. Following is a description by way of example only with reference to the accompanying drawings of methods of carrying the invention into effect. In the drawings:- Figure 1 is an anterior radionuclide image of th pelvis showing the localization of antibody before image enhancement. Figure lb is an anterior radionuclide image of the pelvis showing localization of the antibody after enhancement. Figure 2 illustrates the presence of a secondary in the brain of one of the patients. Figure 3a is a radionuclide image of resected specimen; and Figure 3b is a microscopic section of bowel showing a nodular tumor with a small associated polyp in the adjacent colon wall. EXAMPLE 1 Development of the hvbridoma Male Balb/c mice are injected 7 interperitoneally with 10 cells of osteogenic sarcoma cell line 791T.- One week later a second 7 mterperitoneal inoculation of 10 791T cells is given and the mice are then given a booster inoculation of 2 x 10 791T cells by intracardiac injection five days before their spleens are removed for fusion. The spleens are removed aspectically and cell suspensions are prepared by teasing fragments in RPM1 1640 medium. 10 8 spleen cells are then fused with 107 P3NS1 cells using 50% polythethylene glycol. The supernatants are then screened for reactivity against 791T cells and other targets using a 125I-labelled Protein A binding test. Positive hybridomas are then cloned in 0.3% agar as described by Gunn et al Int. J. Cancer 2_6 ;1980;325-330. Essentially, antibody-positive mass cultured hybridoma cells were suspended in 0.3% agar in RFMI + 10% FCS and seeded over a thin layer of 0.5% agar overlying a feeder layer 2 of rat peritoneal exudate cells in 25 cm culture flasks. Colonies growing from single cells were isolated and grown separately. The supernatants of each clone were screened for anti-791T antibody and negative clones were discarded. The antibodies were prepared by diluting the ascites fluid 1:1 in 0.1 molar citrate phosphate buffer at a pH of 7.5. The fluid so prepared is then passed through a Sepharose-Protein A column. After extensive washing of the column, immunoglobulins are eluted with citrate-phosphate buffer at a pH of 3 with a 12 ml/h flow rate using a LKB Ultragrad gradient mixer of the type supplied by LKB of South Croydon, Surrey, England. The material eluted at pH 3 is pooled, dialysed against phosphate buffer sulphate, and concentrated by positive pressure membrane ultra-filtration to produce monoclonal antibody designated XMMCO-791 monoclonal antibody. Hybridoma cell line XMMCO-791 was deposited with the American Type Culture Collection (A.T.C.C.), Rockville, MD 20852-1776, on August 14, 1986, and given A.T.C.C. Accession No. HB 9173.. EXAMPLE 2 The antibody thus prepared is labelled with iodine 131 using the iodogen method described by Fraker and Speck in 1978. For labelling purposes, 300yl aliquots of iodogen (1, 3, 4, 6-tetrachloro-3a, 6a-diphenylglycouril as supplied the Pierce Chemical Co., Chester, Cheshire, England) are combined with 4yg/ml of antibody in me hylene chloride and are evaporated to dryness under nitrogen in conical polypropylene tubes, of the type supplied by Sarstedt of Leicester, Leicestershire, England. The sodium iodide isotype of iodine 131 of a grade suitable for protein iodination as supplied by the Radiochemical Centre, Amersham, Bucks., England, together with protein at a concentration of lmg/ml are added to the tubes and incubated for 15 min at room temperature. The reaction is stopped by removing the reaction mixture from the Iodogen-coated tubes. Free radioiodine is separated by the passage of reaction mixture through Sephadex G25 in phosphate buffer solphate (supplied by Pharmacia, of Uppsala, Sweden). For this purpose, the antibody is labelled in 5 Mci I 131 /500yg 79H/36. The radioactivity in antibody preparations is counted and the antibody antibody solution then sterilized by filtration through 0.22 micron membrane filters. 2 ml of sterilized preparation containing approximately 20 μg of antibody is then added to 200 ml of sterile saline preparatory for administration by injection. EXAMPLE 3 Eleven patients were studied, five were known to have primary rectal colon cancers, and six had extensive disseminated disease histologically confirmed at a previous laparotomy. One patient with a secondary disease had received a radiotherapy dose of 30 Gy to his inoperable • rectal tumor 2 weeks before the infusion of radiolabelled antibody. Another patient had a discrete secondary in the brain and the remainder had disease restricted to the abdomen. The mean age of the patients was 64 years (44-75), 3 were female and 8 were male. The nature of the study was clearly explained to the eleven patients who gave their informed consent. The thyroid uptake of radioiodine was blocked by 60mg of potassium iodide per day for two weeks starting at least 24 hours before the injection of the antibody. One mil of antibody solution was injected subcutaneously into each patient's right arm 30 minutes before the infusion of the antibody to test for anaphylaxis. Patients lymphocytes were tested in vitro with the antibody to ensure there was no cross-reaction with their normal cells. Twenty-four hours after the administration of the I 131 labelled antibody, anterior and posterior images of the abdomen and pelvis were taken with gamma camera and recorded by computer. Other sites were imaged as required. Views were subsequently taken at 48 and 72h in the patients not undergoing surgery. Image enhancement was achieved by subtraction of background radioactivity as described by DeLand et al in a paper entitled " Imaging approaching radioimmuno-detection reported in Cancer Research 1980: 40 :3046-3049. The patients red blood cells were labelled in vivo with ""TC and depending upon the position of the tumor, in-labelled indium chloride solution was given to label the blood transferin. After normalisation to equalise the counts recorded in each image, the " c and In-images of the blood pool were subtracted from the corresponding 131 I-labelled antibody images. The tumours in the five patients with the primary cancers were resected 48 h after the administration of the 131I-labelled antibody and were then immediately imaged again to assess the distribution of the labelled antibody. The relative uptake of 131I-labelled antibody per gram of tissue was further determined by measuring the radioactive count rates from the tumours and by comparing these activities with count rates from adjacent areas of the normal colon tissues. The results are set out in Table 1 as shown below: - TUMOR Patient Age Macroscopic Grade/ (Sex) differentiation 1 71 Primary nodular Moderate M Ca of sigmoid (5x6x2cm) 2 66 Primary nodular Well Ca rectosigmoid (44x3cm) 75. Primary nodular Moderate M Ca sigmoid (4x3 3cm) 67 2 primaries, Moderate M transverse and rectum (3x3x2cm, 4x3x4cm) 64 Primary ulcerating Well M Ca sigmoid (6x3x3cm) 58 Disseminated Ca Moderate with σmeπtal 2° postop (10x15x3cm) 71 Disseminated Ca Moderate M with liver 2° postop (6x6x3cm) 50 Disseminated Ca Moderate M with 2° in liver postop 72 Inoperable Ca Moderate M rectum treated by radiotherapy 30 GY 44 Disseminated Ca Moderate M Caecum 2° in liver and brain postop (2x2xlcm brain) 60 Disseminated Ca Moderate F in sigmoid with pelvis recurrence (6x6x5cm) TABLE tContinued) IMAGING Tumor to non-tumor ratios Patient Background Site of Before After Subtraction image Subtraction background Agent subtraction 99m TcRBC Positive 1.5/1 8.0/1 113m In- primary in pelvis transferrin 99m TcRBC Positive; 1.5/1 2.1/1 primary in pelvis attached to bladder 99m TcRBC Not detected; behind bladder 99m TcRBC Positive for 1.5/1 2.1/1 both epigastrium and pelvis 99m TcRBC Positive; 1.2/1 1.5/1 primary in pelvis 9m Tc cRBC Positive; 2.0/1 8.1/1 peritoneal and omental 2° 31 99m TcRBC Positive; 1.2/1 5.1/1 113m In pelvis and liver transferrin 99m TcRBC Positive; 1.5/1 4.4/1 2° in liver 99m TcRBC; Not detected 99m Tc sulphur colloid transferrin 99m TcRBC Positive; 2° 1.3/1 4.0/1 113m. In- in brain and transferrin liver 99m RBC; Positive; mass 1.9/1 4.3/1 113m anterior to In- rectum transferrin Table 2 illustrates the results of postoperative imaging and counting of the five resected specimens. Tumor to Tumor to non-tumor non-tumor Patients Tumour Size of ratio on counts gram resected image of tissue Case 1 Primary 5x6x2cm 2.3/1 2.2/1 nodular Ca sigmoid Case 2 Primary 4x4x5cm 2.5/1 5.8/1 nodular Ca rectosigmoid Case 3 Primary 4x5x3cm Not imaged 2.1/1 nodular Ca rectosigmoid Case 4 2 Primary 3x3x2cm 2.1/1 3.1/1 ulcerating Ca-rectum and transverse 4x4x2cm 2.0/1 Not counted colon* Case 5 Primary 6x3x3m 1.5/1 1.1/1 ulcerating Ca of sigmoid colon * Undiagnosed carcinoma identified on image. From the foregoing it will be appreciated that all eleven patients tolerated the procedure well and there were no untoward reactions. Temperature and pulse rate remained stable during infusion and for two weeks after the injection, and during the pre-infusion incubation studies the patients' small lymphocytes did not cross react with the monoclonal antibody. In 10 out of 11 patients, the infused iodine-131-labelled antibody became localised within the cancer deposits shown in table 1 with mean tumor to non-tumor ratio of 1.5/1 before subtraction and 4.4/1 after subtraction for the blood pool. In one of the negative preoperative studies, case 3, the subsequent image of the resected specimen were positive (Table 2) and failure initially to demonstrate this patient's tumor was thought to be the result of its being obscured by the bladder. The in vivo release of iodine 131 from the antibody and its excretin in the urine produced bladder images in all patients. In the 9 cases with a positive image on the gamma camera, the imaged site exactly matched the site of the tumor documented clinically and at operation. Figure 1 (Case 6) shows a large omental mass arising from the pelvis of a woman with ascites and an obvious palpable recurrence. In case 4, not only was the primary rectal carcinoma identified preoperatively, but a hitherto undiagnosed second synchronous tumor was also seen; the barium enema examination had only demonstrated the original rectal cancer. In case 10, a secondary of the brain was clearly identified (see Figure 2). This accorded with the patient's right hemiplegia and was later confirmed at necropsy. This was the smallest tumor identified. It measured 2x2xlcm. There was no correlation between the stage, macroscopic appearance, or microscopic grade of any of the tumours and the uptake of antibody. Four out of the 5 patients with primary tumours had a positive preoperative image (the negative image was produced by the patient's bladder obscuring the tumor), and all resected specimens demonstrated 5 uptake by the cancer deposits (see Table 2). The mean tumor to non-tumor uptake ratio in the specimens was 2.1 (range of 1.5 to 2.5/1); in case 4 two resected tumours were identified on imaging with uptake ratios of approximately 2/1. In every case the localization 10 of the iodine 131 labelled monoclonal antibody matched exactly the size and contour of the tumor. Figure 3 demonstrates the degree of localization achieved. Not only is the nodular tumor seen, but a 1 cm diameter polyp can also be clearly identified. 15 The count per gram of cancer tissue compared with that in the normal colon, in the resected specimens, ranged from 1.1/1 to 5.8/1 with a mean value of 2.8/1. In the two patients (cases 1 and 2) where the tumor was resected two days after infusion of the 20 labelled antibody, the resected tumor contained 0.005% of the injected dose of iodine 131 per gram of tumor tissue. 25 30 35 -15 / 1- Hybridoma cell line XMMCO-791 was deposited with the American Type Culture Collection (A.T.C.C.), Rockville, MD 20852-1776, on August 14, 1986, and given A.T.C.C. Accession No. HB 9173.

Claims: 16 CLAIMS 1. A method of detecting tumor associated antigens which method comprises: (i) preparing samples of hybridoma XMMCO-791 having A.T.C.C. Accession No. HB 9173, (ii) separating and purifying the associated antibody XMMCO-791 to obtain the IgG2b isotype, (iii) labelling the antibody thus obtained with a radioactive label, (iv) preparing a composition containing an effective concentration of said labelled antibody, (v) administering said antibody composition to a patient, and (vi) screening said patient to detect concentrations of radioactivity thereby indicating a concentration of antibody. 2. A method as claimed in claim 1 wherein the antibody is labelled with I 131 . 3. A method as claimed in claim 2 wherein the screening was effected using a gamma camera. 4. A method as claimed in claim 3 wherein an image enhancement technique is employed. 5. A method as claimed in claim 4 wherein the image enhancement technique includes blood cell and blood transferrin labelling with isotypes selected from at least one of the group consisting of "^C and 6. Hybridoma cell line XMMCO-791 having A.T.C.C. Accession No. HB 9173. 3 7. Monoclonal antibodies or active fragments thereof produced by hybridoma cell line XMMCO-791 having A.T.C.C. Accession No. HB 9173. 8. Monoclonal antibodies or active fragments thereof haveing substantially the same binding activity as those produced by hybridoma cell line XMMCO-791 having A.T.C.C. Accession No. HB 9173.

Inventors: BALDWIN ROBERT WILLIAM, BALDWIN, ROBERT, WILLIAM
Applicants: XOMA CORP, XOMA CORPORATION
Application year: 1987
Main classification: A61K43
IPC codes: A61K51, C07K16, C12N5, C12N15, C12P21, C12Q1, G01N33