Histological correlation of 17 prospective immunoscintigraphies of recurrences of colorectal carcinomas using indium-111-labeled anti-cea and(or) 19-9 monoclonal antibodies

Seventeen patients (mean age 55 years) with suspected recurrence in previously operated and histologically confirmed colorectal adenocarcinomas were explored by immunoscintography (IS) associating planar and emission computed tomography (ECT) and using the ¹¹¹In-labeled anti carcinoembryonic antigen (CEA) and(or) 19-9 monoclonal antibodies (MoAbs). The results of IS were compared blind with those of computed tomography (CT) and ultrasonography (US). The final diagnosis of recurrence and(or) metastasis was done in 16 cases by second-look surgery and in another patient by rectal biopsy. Overall per-patient sensitivity for the pelvis and extrahepatic abdomen was 69% for IS and 31% and 25% respectively for computed tomography and ultrasonography. No false positive of IS, as well as US and CT, for the pelvis and the extrahepatic abdomen was seen. Based on the number of anatomical sites tested, sensitivity of IS was 91% in the pelvis. In our series, scintigraphic computer subtraction did not allow adequate resolution of the problem of intense liver uptake of ¹¹¹In-labeled MoAbs. It is concluded that IS using ¹¹¹In-labeled anti CEA and(or) 19-9 MoAbs should be carried out prospectively in patients at high risk of recurrence of colorectal cancer.     

Multi-centre immunoscintigraphic study using indium-111-labelled CEA-specific and/or 19-9 monoclonal antibody F(ab')2 fragments

Six European nuclear medicine centres performed immunoscintigraphy first retrospectively in 34 patients using indium-111-labelled carcinoembryonic antigen (CEA)-specific and/or 19-9 F(ab')2 fragments. Results for sensitivity and specificity in tumour sites were 94% and 87%, respectively, for the pelvis and 73% and 100% for the extrahepatic abdomen. A second prospective series concerned 58 other patients previously operated on for colorectal adenocarcinoma (27 colon, 31 rectum). Two-thirds of these patients had a suspected recurrence signalled by an isolated rise in tumour markers, and 46 patients examined by immunoscintigraphy, X-ray computed tomography and ultrasonography were found to have a recurrence (a total of 62 tumour sites). Sensitivity and specificity with immunoscintigraphy were 90% and 97%, respectively, for the pelvis and 62% and 95% for the extrahepatic abdomen. For 29 patients injected with CEA-specific fragments, sensitivity was 90% and specificity 94% for the pelvis. For 25 patients injected with 19-9 fragments, pelvic sensitivity and specificity were 80% and 100%, respectively, whereas sensitivity for the extrahepatic abdomen was only 29% since several cases of peritoneal carcinosis were not visualized. In the prospective series, comparison of the three imaging techniques for all tumour sites (including liver and in 5 cases thorax) gave a sensitivity and specificity of 82% and 91%, respectively, for immunoscintigraphy, 52% and 95% for X-ray computed tomography and 59% and 100% for ultrasonography. These results thus confirm the advantage of using 111In-labelled CEA-specific or 19-9 to visualize and localize recurrences of colorectal cancer.     

Feasibility study of radioimmunoguided surgery of colorectal carcinomas using indium-111 CEA-specific monoclonal antibody

The study was undertaken to define the potential use of indium 111 carcinoembryonic antigen-specific antibody labelled [CEA F(ab)2] for the radioimmunodetection of colorectal carcinoma using an intraoperative hand-held gamma probe. The use of a linear radioactive source allowed optimization of physical characteristics. The best results regarding sensitivity and resolution were obtained using a 5-mm thick tungsten alloy collimator. A simulation study with a liver phantom (22 MBq or 0.6 mCi) was performed to determine the effect of side scatter as opposed to direct background and showed that it is possible to detect small radioactive targets (3.7 KBq or 0.1 Ci) 4 cm from the phantom. A clinical study performed with ten patients showed that tumours with good uptake of CEA-specific antibody could be detected with sufficient contrast in two patients when the probe was used. Results of a biodistribution study performed after tumour fragment or normal tissue countings in a well counter showed high tumour uptake (above 8 x 10^–3 injected dose/g) and tumour-to-normal tissue ratios (between 2.5 and 20) in five patients. Results with the probe showed markedly lower ratios. There was no correlation between absolute tumour uptake and the count rates of tumour measured intraoperatively. This can be attributed to the degradation of depth resolution resulting from the high energy photopeak of gamma-emitting¹¹¹In.     

Feasibility study of radioimmunoguided surgery of colorectal carcinomas using indium-111 CEA-specific monoclonal antibody

The study was undertaken to define the potential use of indium 111 carcinoembryonic antigen-specific antibody labelled [CEA F(ab')2] for the radioimmuno-detection of colorectal carcinoma using an intraoperative hand-held gamma probe. The use of a linear radioactive source allowed optimization of physical characteristics. The best results regarding sensitivity and resolution were obtained using a 5-mm thick tungsten alloy collimator. A simulation study with a liver phantom (22 MBq or 0.6 mCi) was performed to determine the effect of side scatter as opposed to direct background and showed that it is possible to detect small radioactive targets (3.7 KBq or 0.1 mu Ci) 4 cm from the phantom. A clinical study performed with ten patients showed that tumours with good uptake of CEA-specific antibody could be detected with sufficient contrast in two patients when the probe was used. Results of a biodistribution study performed after tumour fragment or normal tissue countings in a well counter showed high tumour uptake (above 8 x 10(-3) injected dose/g) and tumour-to-normal tissue ratios (between 2.5 and 20) in five patients. Results with the probe showed markedly lower ratios. There was no correlation between absolute tumour uptake and the count rates of tumour measured intraoperatively. This can be attributed to the degradation of depth resolution resulting from the high energy photopeak of gamma-emitting 111In.     

Multi-centre immunoscintigraphic study using indium-111-labelled CEA-specific and/or 19-9 monoclonal antibody F(ab′)2 fragments

Six European nuclear medicine centres per formed immunoscintigraphy first retrospectively in 34 patients using indium-111-labelled carcinoembryonic antigen (CEA)-specific and/or 19-9 F(ab')₂ fragments. Results for sensitivity and specificity in tumour sites were 94% and 87%, respectively, for the pelvis and 73% and 100% for the extrahepatic abdomen. A second prospective series concerned 58 other patients previously operated on for colorectal adenocarcinoma (27 colon, 31 rectum). Two-thirds of these patients had a suspected recurrence signalled by an isolated rise in tumour markers, and 46 patients examined by immunoscintigraphy, X-ray computed tomography and ultrasonography were found to have a recurrence (a total of 62 tumour sites). Sensitivity and specificity with immunoscintigraphy were 90% and 97%, respectively, for the pelvis and 62% and 95% for the extrahepatic abdomen. For 29 patients injected with CEA-specific fragments, sensitivity was 90% and specificity 94% for the pelvis. For 25 patients injected with 19-9 fragments, pelvic sensitivity and specificity were 80% and 100%, respectively, whereas sensitivity for the extrahepatic abdomen was only 29% since several cases of peritoneal carcinosis were not visualized. In the prospective series, comparison of the three imaging techniques for all tumour sites (including liver and in 5 cases thorax) gave a sensitivity and specificity of 82% and 91 %, respectively, for immunoscintigraphy, 52% and 95% for X-ray computed tomography and 59% and 100% for ultrasonography. These results thus confirm the advantage of using¹¹¹In-labelled CEA-specific or 19-9 to visualize and localize recurrences of colorectal cancer.This study was presented in part at the congress of the European Association of Nuclear Medicine in Strasbourg, France, on August 31, 1989, and has appeared in abstract form (Eur J Nucl Med (1989) 15:438)     

Pharmacokinetics of indium-111-labeled B72.3 monoclonal antibody in colorectal cancer patients.

Mean time parameters provide a new approach to plasma pharmacokinetics of radiolabeled Mabs that may show important patient differences affecting diagnosis or treatment. We determined mean time pharmacokinetic parameters for 11 patients entered in a Phase I/II clinical trial for detection of colorectal cancer. Patients were administered 0.5-2 mg of B72.3 anti-TAG-72 radiolabeled with 3.5-5 mCi of 111In, plasma activity was measured over time. Mean time pharmacokinetic parameters were (mean +/- s.e.m.): mean residence time; body (MRTB) 88.9 +/- 7.2 hr, central (MRTC) 73.8 +/- 6.0 hr; mean transit time, central (MTTC) 41.1 +/- 9.0 hr; mean residence time, periphery (MRTP) 15.1 +/- 3.4 hr; intrinsic mean residence time, periphery (IMPTP) 39.0 +/- 7.6 hr; mean transit time, periphery (MTTP) 24.0 +/- 6.7 hr; probability of distribution (PRD) 50% +/- 10%; and n compartmental cycles of 4.54 +/- 2.3 times. In patients with increased circulating specific TAG-72 antigen, MRTC greater than MTTC and n much greater than 1. In patients without specific antigen, MRTC approximately equal to MTTC and n much less than 1. Pharmacokinetic studies may identify patients who do not have the tumor produced target antigen for the specific Mab and may provide an opportunity to select another specific Mab with an increased chance for successful diagnosis or treatment.     

Differences in biodistribution of indium-111-and iodine-131-labeled B72.3 monoclonal antibodies in patients with colorectal cancer

We have compared the biodistributions of [131I]B72.3 and 111In-SCN-Bz-DTPA B72.3 monoclonal antibody (MoAb) in patients with metastatic colon cancers. B72.3 is an IgG1 that recognizes a mucin-like colon cancer associated antigen. Eight patients were infused with 3-5 mCi and 0.36-20 mg of 111In-labeled B72.3 prepared with a bifunctional chelate, isothiocyanatobenzyl-DTPA (SCN-Bz-DTPA). The biodistribution was compared with that of 13 patients previously studied as part of a separate trial, with 1-10 mCi and 0.16-1.35 mg of [131I]B72.3. The Beta T1/2 in serum was 63 +/- 5 hr for 111In-SCN-Bz-DTPA B72.3 and 52 +/- 10 hr for [131I]B72.3. Whole-body retention of the 111In (T1/2 = 11.8 days) was significantly longer than for [131I]B72.3 (T1/2 = 3.3 days), p less than 0.000001. The 131I was excreted primarily through the urine. Urinary excretion of 111In was low and gamma camera images confirmed that some 111In was excreted in the bowel. Tumor localization was seen in one of seven evaluable patients receiving 111In-SCN-Bz-DTPA B72.3. Gamma camera images showed that the liver concentrates 111In but not 131I. We conclude that 111In-SCN-Bz-DTPA B72.3 is metabolized in a different manner from the iodinated B72.3. The high concentration and prolonged retention of 111In by the liver interferes with tumor imaging of metastases.     

Localization of pulmonary human sarcoma xenografts in athymic nude mice with indium-111-labeled monoclonal antibodies

In order to study localization of metastatic tumors with a radiolabeled monoclonal antibody, a pulmonary metastases model was devised in athymic mice. Metastatic pulmonary sarcoma colonies were verified by histological examination. A murine monoclonal antibody (MAb 19-24) directed against a human sarcoma antigen was labeled with indium-111 (111In) by use of the linker 1-(p-isothiocyanatobenzyl)-diethylenetriaminepentaacetic acid (SCN-Bz-DTPA). MAb P3 was similarly labeled as a negative control. In the group given MAb 19-24, the percent injected dose per gram lung tissue bearing tumor colonies (30.1%, 29.6%, and 27.7% on Days 1, 2, and 3, respectively) was significantly (p less than 0.05) higher than in those receiving MAb P3. Hepatic activities of both 111In-MAb 19-24 and 111In-MAb P3 were low. The lungs with tumor colonies demonstrated clearest images on Day 3. The specific binding of 111In-SCN-Bz-DTPA-labeled MAb 19-24 to pulmonary xenografts without appreciable liver uptake indicates that it may be useful in the clinical localization of pulmonic metastatic lesions.     

Semiquantitative in vitro binding assay of indium-111-labeled monoclonal antibodies to human cancer and normal tissues

We have developed a simple in vitro method for the semiquantitative assessment of the radiolabeled antibody binding to cancer and normal tissues. Indium-111-labeled F(ab')2 fragments of 17-1A and 19-9 monoclonal antibodies with well-characterized specificity for gastrointestinal cancer demonstrated similar binding properties between cultured cancer cells and membrane fractions of homogenates prepared from tumor tissues. All of the 17 colon cancer specimens and seven (64%) of 11 gastric cancer specimens obtained by surgery showed positive binding with 17-1A. Specific binding of 19-9 was observed in 9 (53%) colon cancers and 4 (36%) gastric cancers. However, some normal colon tissues were also positive with 111In-labeled 17-1A. Relative levels of CA 19-9 antigen expression, determined by the binding with radiolabeled antibodies, correlated with percent positive cells determined by the immunohistochemical assays. Furthermore, membrane fractions could be cryopreserved without losing antibody-binding activity. These results indicate that this assay can be used for testing the immunoreactivity of radiolabeled anti-tumor antibodies and in vitro binding properties to cancer and normal tissues.     

Detection of subacute infectious foci with indium-111-labeled autologous leukocytes and indium-111-labeled human nonspecific immunoglobulin G: a prospective comparative study

In 35 patients suspected of an infectious focus, the outcome of scintigraphy with 111In-labeled autologous leukocytes (WBC) and 111In-labeled human nonspecific immunoglobulin G (IgG) was evaluated in a prospective comparative study. Clinical, roentgenologic and microbiologic findings were considered to be proof of the presence of infection or inflammation. In this group of patients with mainly subacute infections, 111In-IgG scintigraphy performed significantly better than 111In-WBC scintigraphy, especially in infections of the locomotor system, but also in various soft-tissue infections. Both techniques showed disappointing results in patients with disseminated yersinia infection and in some patients with tuberculosis. Overall sensitivity and specificity was 74% and 100% for 111In-IgG scintigraphy and 52% and 78% for 111In-WBC scintigraphy, respectively.     

Immunoscintigraphy of ovarian cancer with indium-111-labeled OV-TL 3 F(ab')2 monoclonal antibody

The safety and diagnostic accuracy of immunoscintigraphy with the indium-111-labeled monoclonal antibody OV-TL 3 F(ab')2(111In-OV-TL 3 F(ab')2) for diagnosis and follow-up of ovarian cancer was prospectively studied in 31 patients. Planar and SPECT scintigraphy were performed up to 4 days after i.v. injection of 140 MBq 111In-OV-TL 3 F(ab')2. Surgical evaluation was possible in 22 out of 31 patients. Imaging results were compared with X-ray computed tomography, ultrasound, and CA 125 serum level using the histologically confirmed surgical findings as a "gold standard." Apart from a transient rash observed in two patients, no other immediate or delayed adverse reactions were observed. Within the surgically evaluated group, ovarian cancer lesions were detected in 16 out of 17 patients (94%). Of 45 distinct tumor deposits found at operation, 67% were detected and localized with immunoscintigraphy while X-ray computed tomography and ultrasound visualized 53% and 23%, respectively.     

Preparation and immunoreactivity of high specific activity indium-111-DTPA labeled monoclonal antibody (MoAb) using ultrapure indium-111

The preparation of high-specific activity 111In-DTPA-MoAb without increasing the number of DTPA molecules per Ab was investigated. Instant thin layer chromatography was used to assay the relationship between labeling efficiencies and specific activities. With ultrapurified 111In, the specific activity of the radiolabeled MoAb approached the expected theoretic maximum of 100 muCi/microgram. The bioactivity of such high-specific activity preparation showed no degradation as measured by in vitro cell binding assay.     

Radioimmunoimaging of lung vessels: an approach using indium-111-labeled monoclonal antibody to angiotensin-converting enzyme

A murine monoclonal antibody against human angiotensin-converting enzyme was radiolabeled with 111In via diethylenetriaminepentaacetic acid without substantial loss of antigen-binding capacity. This monoclonal antibody designated 9B9 cross-reacted with rat and monkey angiotensin-converting enzyme. Indium-111-labeled 9B9 selectively accumulated 10-20 times greater in the lung than in blood or other organs following intravenous administration in rats. Kinetics of lung accumulation and blood clearance were studied for 111In-9B9-antibody and compared to that of 125I-labeled 9B9 in rat. Highly specific accumulation of 111In-9B9-antibody in the lung of Macaca Rhesus monkeys after intravenous injection was monitored by gamma-imaging. Images of 111In-labeled antibody 9B9 biodistribution in monkey lung noticeably differ from the images of biodistribution of 99mTc-labeled albumin microspheres. This difference may provide information concerning the state of the endothelium of lung capillaries, which is different from the blood flow characteristics determined with routine microsphere technique.     

Dosimetric evaluation of immunoscintigraphy using indium-111-labeled monoclonal antibody fragments in patients with ovarian cancer.

This study reports the biodistribution and dosimetry for a monoclonal antibody against ovarian carcinoma. Eight patients received 140 MBq 111In-OV-TL 3 F(ab')2; thereafter gamma camera imaging was performed daily up to 96 hr. By using the conjugated view counting method, activity in the organs was quantitated by phantom calibration and by whole-body measurements using a whole-body counter with the conjugated view counting method. Red bone marrow uptake was derived from regions of interest over the lumbar vertebrae and iliac crest. In both methods, organ uptake varied only slightly with time, having a mean value of approximately 18%, 4%, 6% and 17% of the injected dose in the liver, spleen, kidneys and red bone marrow, respectively. The mean radiation dose to these organs was 0.9, 1.5, 1.2 and 0.5 mGy/MBq. The effective dose equivalent was 0.4 mSv/MBq. In this study, two different methods of uptake calculations, result in similar values of organ uptake.     

Thrombus imaging with indium-111 and iodine-131-labeled fibrin-specific monoclonal antibody and its F(ab')2 and Fab fragments

We have previously reported successful imaging of fresh (2-4 hr old) and aged (1-5 days old) canine thrombi with 131I-labeled intact monoclonal antibody (MAb) specific for fibrin. We now report thrombus imaging with 131I-labeled F(ab')2 and Fab and 111In-labeled intact MAb, F(ab')2, and Fab. Indium-111-labeled F(ab')2 proved to be the best imaging agent due to less nonspecific binding in the liver than whole IgG. Image quality was improved by the higher administered dose permissible with 111In and its better physical characteristics for imaging, compared to 131I. Immunofluorescence of fresh human histologic sections showed intact MAb and F(ab')2 binding to thrombi, pulmonary emboli, and atherosclerotic plaques, strengthening the feasibility of clinical thrombus imaging.     

Imaging of tumor in patients with indium-111-labeled biotin and streptavidin-conjugated antibodies: preliminary communication

Tumor localization in patients has been achieved through the in vivo use of streptavidin and biotin. In these preliminary studies, the monoclonal antibody HMFG1 was conjugated with streptavidin and 1 mg was administered intravenously to each of 10 patients with documented squamous cell carcinoma of the lung. Two to 3 days later, 111In-labeled biotin was also administered intravenously. No evidence of toxicity was observed. Background radioactivity levels were reduced in liver (1% ID at 24 hr) and kidneys (2%) and in all other normal tissues and blood. Images of lung tumor were obtained in as little as 2 hr following administration of labeled biotin. In eight patients, tumor was detected with labeled biotin alone without the previous administration of streptavidin-conjugated antibody but in three of these patients, the images were improved with the prior administration of conjugated antibody. These results suggest that this approach may improve the tumor-to-normal tissue radioactivity ratios in radioimmunotargeting.     

Metabolism of indium-111-labeled murine monoclonal antibody in tumor and normal tissue of the athymic mouse

We have studied the fate of radiometal metabolism in vivo by analyzing the molecular form of radiolabeled anti-carcinoembryonic antigen (CEA) in tissues. Athymic mice bearing colonic tumor xenografts were injected i.v. with 111In-isothiocyanate-benzyl-DTPA-(SCN-Bz-DTPA) IgG or 111In-(SCN-Bz-DTPA) F(ab')2, and then killed daily for up to four days. Liver, kidney, and tumor were extracted and the supernatants, plasma and urine samples were analyzed by HPLC, ITLC, HPIEC and SDS-PAGE. By HPLC, the activity in normal tissue and tumor was associated principally with two major components. The first was native MAb and the second was a low molecular weight component (LMWF). On Day 1, the native-sized IgG was the predominant form (greater than 65%), but progressively decreased to less than 20% by Day 4. For the F(ab')2, even by Day 1 approximately 90% of the activity was associated with the LMWF. This LMWF was resolved further by HPIEC and SDS-PAGE into several metabolites that appear to be 111In-SCN-Bz-DTPA and 111In-SCN-Bz-DTPA bound to peptide fragments.