Immunoscintigraphy for detection of lymph node metastases from breast cancer

Primary Tumor Site, Size, Patients Age and Axillary Lymph Nodes in Breast Cancers

This study considers the correlations between some characteristics of the primary tumor and level of lymph node involvement in 185 primary breast cancers. The average number of lymph nodes was higher in N + women than in N— women. Primary tumors with a diameter of more than 4 cm yielded the highest mean number of lymph nodes (17.5). The risk of developing lymph node metastases was fourfold in tumors with a diameter greater than 2 cm when compared to those with a diameter less than or equal to 2 cm. The most commonly metastasized lymph node level, in both large and small tumors, was the first; however, one-fifth of the patients had simultaneous lymph node metastasis in all three axillary levels. Although the left breast was the most affected (58.9 %), there was no evidence of a different risk of metastasis between the two breasts; 34.1 % of the tumors were multifocal. Lymph node involvement was higher in women under 50 years of age with a primary tumor larger than 2 cm.

The Use of Monoclonal Antibodies for Radioscintigraphic Detection of Cancer

Beginning with Ehrlich's original “magic bullet” concept of 1904, the pioneering human trials in the late 1970s of Goldenberg and Mach using polyclonal antibodies, and the Nobel Prize-winning work of Kohler and Milstein in 1975 for developing monoclonal antibody (MAb) technology, there has been much interest in the use of antibodies for detecting and treating cancer. Although not the revolutionary breakthrough that was initially hoped for, marked progress has been made. The Food and Drug Administration (FDA) has recently approved the intact murine IgG, 111-indium CYT-103 (satumomoab, Oncoscint™ Cytogen, Princeton, NJ) for clinical use in detecting colorectal and ovarian cancer. However, the agent has been approved for only a single, one-time use, because patients developed an immune response (human anti-mouse antibody, or HAMA) that alters MAb biodistribution and may limit the clinical effectiveness of this agent when repeat studies are performed. Other MAbs reacting with a variety of antigens and targeting numerous tumors, including breast, lung, prostate, and melanomas, are currently undergoing large-scale clinical trials. To reduce induction of immune responses, many of the agents use immunoglobulin fragments [Fab, or F(ab)2] labeled with the short-lived isotope 99m-technetium used for most routine nuclear medicine diagnostic testing. Future developments will use even smaller fragments such as single chain antibodies or custom synthesized molecular recognition units (small peptides containing only the specific antigen combining site). Presented herein is an overview of the past results and an assessment of the current status of radioimmunoscintigraphy for various neoplasms.

Management of the axilla in operable breast cancer treated by breast conservation: a randomized clinical trial. Edinburgh Breast Unit

BACKGROUND

In the treatment of operable breast cancer by breast conservation, the extent of axillary dissection, the need for radiotherapy to the axilla and the morbidity associated with these procedures have not been assessed adequately.

METHODS

Patients with operable breast cancer were randomized to have level III axillary node clearance (232 patients) or axillary node sample (234 patients). Radiotherapy to the axilla was given selectively. Radiotherapy was not given to those who had an axillary clearance. In the early part of the study all patients who had node sample were treated by radiotherapy (54 patients); subsequently this was modified to include only those who were node positive. The morbidity to the shoulder and arm was assessed before and after operation by measuring upper limb volume and circumference, and combined glenohumeral and scapular movement and muscle power.

RESULTS

Comparing the two surgical policies, no difference was found in local (axillary clearance 14 versus sample 15), axillary (eight versus seven) or distant (29 versus 29) recurrence. There was no statistically significant difference in 5-year survival rate (clearance 82.1 versus sample 88.6 per cent). Morbidity was least in those who had a node sample and no radiotherapy to the axilla. Radiotherapy to the axilla in patients who had a node sample resulted in a significant reduction in range of movement of the shoulder, e.g. mean(s.e.) 2.2(0.6) cm reduction in lateral rotation at 3 years. Surgical axillary clearance was associated with significant lymphoedema of the upper limb, e.g. 4.1(0.7) per cent increase in arm volume at 3 years.

CONCLUSION

A selective policy for the management of the axilla is associated with no increase in axillary recurrence or mortality rate compared with routine axillary node clearance. Patients who are node negative after axillary sample can avoid radiotherapy or axillary clearance.

Immunolymphoscintigraphy in breast cancer: evaluation using 131I-labeled monoclonal antibody B72.3

Noninvasive axillary lymph node staging was investigated using [131I]murine monoclonal antibody B72.3 in 16 patients with breast cancer scheduled for axillary dissection. [131I]B72.3 was injected into ipsilateral finger webs or around the breast biopsy. Scintigraphy to 72 h and gamma-counting/immunohistochemistry of nodes were performed. Specific antibody uptake (%ID/g) and the ratio of specific:nonspecific antibody uptake were not significantly different in tumor-positive versus tumor-negative nodes, suggesting that [131I]B72.3 is unsuitable to discriminate axillary node tumor involvement.

Antibody imaging in breast cancer

Radiolabeled antibodies have been studied by several investigators for their ability to detect and stage breast cancers. Studies with Technetium-99m labeled anti-CEA monoclonal antibodies, Iodine-123, Indium111 labeled anti-mucin antibodies such as HFMG, B72.3, anti-TF and Iodine-125 labeled B72-3 have demonstrated the ability of radioimmunoscintigraphy in detecting over 80% of breast cancer lesions, but lower sensitivity and specificity for accurate staging of the axillae. Non-specific localization of radiolabeled monoclonal antibodies in tumor negative nodes even following lymphoscintigraphy appear to be the major factor limiting the widespread clinical application of radioimmunoscintigraphy in staging newly diagnosed breast cancer patients. Preliminary studies with Tc-99m labeled CEA-Scan appear to indicate a useful role of this agent in distinguishing between benign and malignant breast lesions in patients with indeterminate mammographic findings.

Tumor imaging with monoclonal antibodies

Immunoscintigraphy offers the possibility of specifically targeting human tumors, but the complexity of the human immune system, as well as tumor-related phenomena, prevent monoclonal antibodies from reaching a large number of tumor cells in which they can interact with the antigen. Possible ways to overcome these problems are the use of small fragments, in particular those of genetically engineered humanized antibodies including single immunoglobulin-variable domains, as well as techniques to label the antibody in vivo after a sufficient amount has been taken up by the tumor and the remainder has been eliminated. Despite the low absolute tumor uptake, results of European studies, presently available radiolabeled monoclonal antibodies in gastrointestinal and ovarian cancers yield an average sensitivity of more than 70% with an average specificity of more than 80%, even in otherwise occult tumors. Because of possible tracer uptake in normal liver, the detection rate of liver metastases varies from less than 10% to more than 90%. For the detection of local recurrence in the pelvis, immunoscintigraphy has been found to be more accurate than methods that are based on the imaging of structural changes. Fusion of morphological and functional images might improve the early detection of recurrent and metastatic disease. In melanoma, another tumor that has been extensively studied in Europe, similar results have been obtained, whereas only few data are presently available for other tumors (especially lung and breast cancer).

Diagnosis of breast carcinoma with radiolabeled monoclonal antibodies (MoAbs) to carcinoembryonic antigen (CEA) and human milk fat globulin (HMFG)

The current study attempted to assess the potential proficiency of radioimmunodetection (RAID) of primary, residual, multicentric, and recurrent breast carcinoma using two radiolabeled murine monoclonal antibodies (MoAbs), anti-human milk fat globulin (HMFG1) labeled with iodine (123I) and anti-carcinoembryonic antigen (CEA) labeled with technetium (99Tc). Thirteen patients with suspicious clinical and/or mammographic primary or recurrent breast carcinoma were studied in a phase I-II prospective, consecutive, nonrandomized, noncontrolled study. Five patients received intravenous infusion with 0.5-2.0 mg anti-CEA MoAb type CYT 380 labeled with 99Tc [13-22 millicurie (mCI)] and 8 patients received intravenous infusion with 0.25-1.0 mg anti-HMFG1 MoAb (Unipath, U.K.) labeled with 123I (4-17 mCI). Both MoAbs used in this study demonstrated ability to bind specifically to breast cancer lesions, resulting in successful RAID in 10 of 12 of studied patients (5 of 5 patients in the anti-CEA-99Tc and 5 of 7 in the anti-HMFG-123I group--accuracy 83.3%). One patient was excluded due to protocol violation. Seven patients had true-positive scans when correlated with surgery (sensitivity 87.5%). The MoAb scans accurately diagnosed lesions in 3 of the 4 primary invasive breast carcinomas confirmed histologically. Presence of residual carcinoma following wide excision was established in 1 of 2 patients and presence of soft tissue metastases in 3 patients. Three patients had true-negative scan (specificity 75%): 2 patients presented with suspicious mammographic recurrence postlumpectomy and 1 patient had questionable soft tissue recurrence. One patient with primary breast carcinoma had a false-negative scan and another had a false-positive scan in the presence of fibrosis following lumpectomy and radiation therapy. No adverse reactions were noted in the patients studied. RAID findings were confirmed by immunohistochemistry in 6 of 9 cases studied. Our data suggest that radiolabeled MoAbs used in this study are potentially useful diagnostic agents for evaluation of primary or recurrent breast carcinoma, particularly in the areas where conventional methodology is limited.

Current status of cancer immunodetection with radiolabeled human monoclonal antibodies

The use of radiolabeled murine monoclonal antibodies (MoAbs) for cancer immunodetection has been limited by the development of human antimouse antibodies (HAMA). Human monoclonal antibodies do not elicit a significant human antihuman (HAHA) response. The generation and production of human monoclonal antibodies met with technical difficulties that resulted in delaying their clinical testing. Human monoclonal antibodies of all isotypes have been obtained. Most were immunoglobulin (Ig) M directed against intracellular antigens. Two antibodies, 16.88 (IgM) and 88BV59 (IgG3k), recognize different epitopes on a tumor-associated antigen, CTA 16.88, homologous to cytokeratins 8, 18, and 19. CTA 16.88 is expressed by most epithelial-derived tumors including carcinomas of the colon, pancreas, breast, ovary, and lung. The in vivo targeting by these antibodies is related to their localization in nonnecrotic areas of tumors. Repeated administration of 16.88 over 5 weeks to a cumulative dose of 1,000 mg did not elicit a HAHA response. Two of 53 patients developed a low titer of HAHA 1 to 3 months after a single administration of 88BV59. Planar imaging of colorectal cancer with Iodine-131 (131I)-16.88 was positive in two studies in 9 of 12 and 16 of 20 patients preselected by immunohistochemistry. Tumors less than 2 cm in diameter are usually not detected. The lack of immunogenicity and long tumor residence time (average = 17 days) makes 16.88 a good candidate for therapy. Radioimmunlymphoscintigraphy with indium-111 (111In)-LiLo-16.88 administered by an intramammary route was used in the presurgical staging of primary breast cancer. The negative predictive value of lymph node metastases for tumors less than 3 cm was 90.5%. Planar and single photon emission computed tomography imaging of colorectal carcinoma with technetium-99m (99mTc) 88BV59 was compared with computed tomography (CT) scan in 36 surgical patients. The antibody scan was more sensitive than the CT scan in detecting abdominal and pelvic tumors: 68% versus 40% (P < .05). The combination of antibody scan and CT scan was superior to CT scan alone: 80% versus 40% (P < .01). Lesions as small as 0.5 cm in diameter were detected by antibody scan. The CT scan appears superior to the antibody scan for liver metastases. Patients with a high serum titer of HAMA from previous exposure to murine antibodies were successfully imaged. Antibody scans obtained with 99mTc-88BV59 have imaging characteristics similar to murine antibody scans obtained with radiolabeled IgGs. The absence or weak immunogenicity of the human monoclonal antibodies makes them good candidates for radioimmunodetection and radioimmunotherapy.

Radioimmunolocalisation in breast cancer using the gene product of c-erbB2 as the target antigen

Lymph node status is still the single most important prognostic factor in breast cancer. Axillary surgery remains the only reliable means of providing this information. This pilot study evaluates using a highly specific radiolabelled monoclonal antibody to provide equivalent information by a non-invasive technique. After optimisation of labelling conditions, our first antibody, ICR12 (against the gene product of c-erbB-2) was evaluated in a mouse model system. Twenty-four hours post i.v. injection the mice were killed and their organs, blood and tumours harvested for counting. Tumour localisation was four times greater than that into normal tissues, reaching 20% injected dose per gram of tumour. Eight patients have had this Tc99m-ICR12. Patient selection was by immunocytochemical staining of fine needle aspirates from the patient's own breast cancer. After intravenous administration of the immunoconjugate, tomographic images were obtained at 24 h. These results were compared to the subsequent histopathological examinations. Three patients acted as normal controls, one patient was negative due to inappropriate sampling, and two patients had strong membrane staining and provided excellent tumour localisation to both breast primary and regional node metastases. A further two patients only had moderate antigen expression on staining and did not localise well. The good performance of this radiolabelled antibody with patients that strongly stain for the antigen encourages the development of this system as both a method of staging breast cancer and a potential means of immunotherapy in this subgroup of patients.

Management of posterior uveal melanoma

In recent years, there have been a number of advances in the diagnosis and management of patients with malignant melanoma of the posterior uvea (ciliary body and choroid). This review provides a brief update on the current status of diagnostic modalities, such as fluorescein angiography, ultrasonography, computed tomography, magnetic resonance imaging, fine needle aspiration biopsy, and the radioactive phosphorus uptake test. Following that is a more detailed review of the current controversy regarding the natural course of uveal melanomas and the available therapeutic modalities. Current indications, techniques, complications, and results are provided for various forms of management, such as observation, laser photocoagulation, plaque radiotherapy, charged particle radiotherapy, local tumor resection, enucleation, and orbital exenteration.

Development of human anti-murine antibody (HAMA) response in patients

Human anti-mouse antibody (HAMA) response was determined in the serum of 67 patients who received subcutaneously administered radiolabelled murine monoclonal antibodies (MoAb) (50 micrograms-3 mg) for immunolymphoscintigraphy and of 10 patients with advanced colorectal cancer who received murine MoAb-N-acetyl melphalan (MoAb-N-AcMEL) conjugates (amount of MoAb ranged from 120 mg/m2 body surface area to 1000 mg/m2 body surface area) as therapy. A pre-existing low level of apparent human anti-mouse antibody reactivity could be detected in the serum of normal subjects and patients prior to administration of murine MoAb. Subcutaneous administration of low doses of murine MoAb, as used in immunolymphoscintigraphy, was associated with a low incidence (4/67 or 6%) of elevated HAMA response; the use of F(ab')2 fragments was associated with the development of elevated HAMA response in one of three patients. By contrast, therapy with hepatic artery infusion of murine MoAb-N-AcMEL conjugates in three repetitive daily doses (each infusion lasting 2 h) elicited elevated HAMA responses in 10/10 (100%) patients, usually 1-3 weeks after the start of therapy. The HAMA response of patients in the therapy group was higher than those in the immunolymphoscintigraphy study and the use of steroids did not prevent the development of the HAMA response. Further administration of MoAb-N-AcMEL conjugates to a patient, who had already developed HAMA, led to 'serum sickness'-type symptoms and a transient reduction in the HAMA titres. The elevated HAMA response was polyclonal, containing increased levels of both immunoglobulin M and G (IgM and IgG) and was directed against mouse-specific determinant, the isotype (presumed to be the Fc portion), the F(ab')2 and the 'idiotype' of mouse immunoglobulins.

Monoclonal antibodies reactive with human breast or ovarian carcinoma: in vivo applications

Monoclonal antibodies (MoAbs) are unique and useful bioprobes that allow in vivo targeting of membrane-associated or circulating antigens. Most of the clinical trials to date have used low dosages of radiolabeled MoAb given in a single dose. Newer studies have included antibody fragments, repeated injections, intraperitoneal (IP) administration, and other labels such as 90Y. Clinical MoAb trials are often arduous, expensive, and time-consuming to perform. Before human use, animal studies and extensive MoAb characterization are required. The production of pharmaceutical grade, radiolabeled MoAb is technically difficult and costly. Clinical trials require administrative and patient consent as well as extensive written protocols. These studies necessitate interdepartmental and intradepartmental cooperation and coordination. Furthermore, the use of in vivo radiolabeled probes impacts many levels of health care providers from janitorial, nursing, and technical staff to laboratories and physicians. Simple blood tests or disposal of body excretions may concern nursing or technical staff with the possibility of radiation exposure. The responsibility for study design, personnel involvement, and prospective use in patients without a definitive cancer diagnosis ultimately rests with the physician. While many issues have been addressed, additional clinical trials, consideration of safety issues, and standardization between institutions will be necessary before the use of radiolabeled MoAb for diagnosis, management, or therapy of human tumors becomes routine. Continued cooperation and funding should ensure its achievement.

Immunolymphoscintigraphy

Immunolymphoscintigraphy (ILS) refers to lymphatic administration of radiolabeled antibodies for lymph node imaging. Macromolecules such as immunoglobulins are preferentially taken up by lymphatic vessels rather than venous capillaries following interstitial injection. They then travel to regional nodes by lymph flow where they can interact with tumor cells, lymphocytes, or macrophages residing within the node. A variety of radiolabeled antibodies and their fragments have been studied, both in animals and humans, to test their ability to selectively target cells in lymph nodes. Preliminary clinical trials in patients with lymphoma, melanoma, and breast cancer suggest that immunolymphoscintigraphy holds great potential for accurate staging of early malignant disease. The procedure is safe and simple to perform, and offers a noninvasive means to detect small deposits of tumor in regional lymph nodes. Furthermore, direct intralymphatic administration results in even more efficient delivery of immunospecific agents, raising the possibility of radiotherapy by this route.

A perspective of monoclonal antibodies: past, present, and future

In 1975, the development of the technique to produce monoclonal antibodies revolutionized the approach to cancer detection and therapy. Hundreds of monoclonal antibodies to the epitopes of tumor cells have been produced, providing more specific tools for probing the cellular elements of cancer. At the same time, these tools have disclosed greater complexity in the character of these cells and stimulated further investigation. Although there are antibodies to specific epitopes of neoplastic cells, this purity has not provided the improved detection and therapy of cancer first expected. Technical manipulations have provided limited improvement in results, but more sophisticated techniques, such as biologic response modifiers, may be required to attain clinical results that can be universally applied. The intense research in monoclonal antibodies and their application does offer promise that the goal of improved cancer detection and therapy will be forthcoming.

The detection of axillary lymph node metastases from breast cancer by radiolabelled monoclonal antibodies: a prospective study

In a prospective study to assess the accuracy of monoclonal immunoscintigraphy for the detection of axillary lymph node metastases in breast cancer, two murine monoclonal antibodies that react with human breast cancer (3E1.2 and RCC-1) were labelled with 131iodine, and the radiolabelled antibody was injected subcutaneously into the interdigital spaces of both hands of 40 patients, 36 of whom had breast cancer and the remaining four of whom had fibroadenoma (the normal, contralateral axilla was used as a control). Of the patients with breast cancer, the findings from the scintigraphy images were correlated with histopathology or cytology of the axillary lymph nodes; images were regarded as positive and hence indicative of lymph node metastases if the amount of background-subtracted radioactive count in axilla on the side of breast cancer exceeded the contralateral normal side by a ratio greater than or equal to 1.5:1.0 as assessed by computer analysis. Using this method, immunoscintigraphy had an overall sensitivity of 33% (23% with 131I-3E1.2 and 50% with 131I-RCC-1) for the detection of lymph node metastases and a specificity of 63% (67% with 131I-3E1.2 and 60% with 131I-RCC-1) with problems of non-specific uptake by presumably normal lymph nodes. The results of immunoscintigraphy obtained with 131I-RCC-1 (IgG) were superior to 131I-3E1.2 (IgM) although the accuracy of immunoscintigraphy using 131I-RCC-1 (56%) was not much better than preoperative clinical assessment (50%). However, there were cases when immunoscintigraphy using radiolabelled antibody (IgM or IgG) detected axillary lymph node metastases not suspected by clinical examination. Thus it appears that while immunoscintigraphy may be a useful adjunct to preoperative clinical assessment and is simple and safe, a major improvement in its accuracy is needed before it can replace axillary dissection and histological examination in the accurate staging of axilla in breast cancer.

Modern thoughts on lymph nodes in breast cancer

Axillary lymph node status remains the single most useful prognostic parameter in breast cancer patients. As clinical examination, imaging techniques, and lymph node sampling methods cannot accurately assess the axillary node involvement, a complete axillary dissection should always be performed. Moreover, this technique provides an excellent treatment modality for regional disease, abolishing the need for radiotherapy to the axilla. The status of the internal mammary lymph nodes is of less importance in the management of the breast cancer patient.

Murine monoclonal antibodies in breast cancer: an overview

Monoclonal antibody technology has been an important development in breast cancer research. Monoclonal antibodies do not detect 'breast cancer specific' antigens but, rather, they react with normal or modified tissue antigens which are either preferentially or inappropriately expressed upon malignant cells. Thus far a number of monoclonal antibodies that have a preferential reaction with breast cancer tissue have been developed. They have a potential value in immunohistopathology as diagnostic tools and in the recognition of small quantities of malignant cells, in the development of serum assay for tumour markers in breast cancer and in the radio-immunodetection of metastases. There has been success in effecting selective targeting of anticancer agents (cytotoxic drugs, toxins, radionuclides) to tumour deposits and encouraging results are obtained in preclinical in vivo studies. Various clinical studies are now in progress to evaluate the role of monoclonal antibodies in the management of breast cancer.

Application of mammary serum antigen assay in the management of breast cancer: a preliminary report

A monoclonal antibody (3E1.2) based serum test using an enzyme immunoassay has been used to determine circulating levels of the breast cancer associated antigen--mammary serum antigen (MSA). Of 157 patients with early breast cancer (stage I and II) and 199 patients with advanced breast cancer (stage III and IV), 73 per cent and 87 per cent respectively had elevated MSA levels (i.e. greater than 300 inhibition units (IU). Furthermore, 40 of 44 patients (91 per cent) had a significant fall of MSA levels with reduction in tumour load by mastectomy. In addition, there was a correlation of MSA levels with the clinical course: changes in MSA levels correlated with changes in disease status (progressive disease, stable disease, disease regression) in 54 of 61 patients and antedated disease progression or recurrence by up to 8 months in some patients; and in 32 of 36 patients (89 per cent) with no clinical evidence of recurrence MSA levels did not vary by more than 25 per cent of the original MSA value over a period of 2-15 months. MSA is therefore a useful tumour marker in the diagnosis and staging of breast cancer. There is also evidence that serial estimations of MSA levels may be used to detect subclinical recurrence and the fluctuations in MSA levels might be useful in assessing response to therapy. Furthermore, it was also noted that surgical procedures such as fine needle aspiration biopsy or incisional biopsy could lead to a rise in MSA levels.

Radioimmunodetection of cancer with monoclonal antibodies: current status, problems, and future directions

Early studies of immunoscintography with affinity-purified 131I-labeled polyclonal antibodies reactive against oncofetal antigens such as carcinoembryonic antigen (CEA) were moderately successful in detecting metastatic colorectal carcinoma. However, because of low tumor to background ratios of isotope, background subtraction techniques using 99Tc-labeled albumin were required to visualize small lesions. Antisera were often of low titer and lacked specificity. These problems could be overcome for the most part following the development of highly specific monoclonal antibodies (MoAb) against a variety of tumor-associated antigens. A number of clinical trials using 131I- or 111In-labeled MoAb to image tumors have demonstrated successful localization without the use of subtraction techniques. Variables limiting the usefulness of murine MoAb for diagnosis have included increased localization in liver and spleen, tumor vascularity and heterogeneity of antigen expression, and development of human antimurine globulins. Methods to overcome some of these problems are discussed. Radiolabeled MoAb appear useful as an adjunct to conventional diagnostic techniques both as a means to predict which antibodies might be useful for treatment and, in select patients, as a basis for treatment decisions.

The Effect of Human Serum on the Binding Activity of Radiolabelled Monoclonal Antibodies

Three murine monoclonal antibodies (MoAbs), MBrl and MOv2 of IgM isotype and MOv8 of IgG isotype, with restricted reactivity for breast or ovarian carcinomas, were labelled with 125I in the perspective of obtaining specific and stable radioimmunopharmaceutical reagents. The radiolabeled MoAbs were analyzed for their « in vitro » stability in human blood. They were incubated at 37 °C for various lengths of time in human or, as a control, in murine blood and their binding capacity was evaluated by solid-phase RIA and compared with that obtained after incubation with buffer. In human blood, serum and plasma, but not with other components such as erythrocytes, leukocytes, HSA and IgG, the MoAbs revealed a loss of binding reactivity which was marked and constant for the IgM MoAbs, and only occasional for the IgG MoAb. In murine serum the decrease was not so rapid. The same change in the binding capacity was observed when the MoAbs were labelled with 3H or 35S, excluding the involvement of dehalogenating mechanisms. In the perspective of using MoAbs for intracavity therapy the effect of ascitic or pleural fluids on their binding activity was also evaluated. The inhibition of the binding reactivity was not as evident and was not related to the MoAb isotype.

Radiolabeled monoclonal antibody B72.3 localization in metastatic lesions of colorectal cancer patients

We have previously demonstrated a high degree of selective binding of monoclonal antibody (MAb) B72.3 to carcinomas of the colon, ovary, and breast in contrast to normal adult tissues using in vitro assays. In this report we demonstrate selective tumor localization in colorectal cancer patients after intravenously administering 131I-labeled MAb B72.3 IgG. Radiolocalization Indices (RI) (i.e. cpm 131I-labeled MAb per gram of tumor vs cpm per gram of normal tissues), were obtained by direct analyses of biopsy materials. Using an RI of greater than or equal to 3 as a positive localization, tumor lesions in various sites from 17/20 patients scored positive. In eight of these patients, all tumor lesions demonstrated RIs of greater than 3, while in five patients RIs of some lesions were greater than 10 and as high as 30-46. Seventy percent (99/142) of the tumor lesions showed RIs of greater than 3, while only 12 of 210 histologically confirmed normal tissues examined showed RIs of greater than 3. These tissues were either adjacent to the tumor or the draining tumor masses or, as in the case of two patients, was caused by high levels of circulating immune complexes that deposited in the spleen. Positive scintigraphic images (confirmed at surgery) were observed in 14/27 patients. No toxicity or adverse reactions were observed with either MAb. These studies provide absolute quantitative analyses of the actual delivery of radiolabeled MAb to carcinoma lesions vs a wide range of adjacent and distal normal tissues and establishes the means for other diagnostic and potential therapeutic applications of this antibody alone, or in combinations with other monoclonal antibodies.

Immunoscintigraphic evaluation of lymph node involvement in prostatic carcinoma

Five patients who were candidates for radical prostatectomy were investigated. One milligram of diethylene triamine pentaacetic acid derivatives of purified F(ab')2 fragments of monoclonal antibodies against prostatic acid phosphatase, labeled with 99mTc, were bilaterally injected into the periprostatic space. The amount of radioactivity injected varied between 3 and 7 mCi. Imaging took place dynamically for the first hour following injection, then at 6 and 24 hr. In one patient, lymph node metastases were detected in the left paraaortic, iliac, and obturator lymph nodes by this technique. The lesions incorporating radioactivity were confirmed to be metastases of prostatic cancer following staging pelvic lymphadenectomy. Immunolabeling electron microscopy studies revealed internalized antibody in prostatic cancer cells. In the four other patients, radioimaging did not show any lymph node metastases, and this negative finding was confirmed at surgery. These early data indicate the possibility of preoperative staging of prostatic cancer using radiolabeled derivatives of monoclonal antibodies raised against prostatic acid phosphatase and injected into the periprostatic area.

Antibody-mediated targeting in the treatment and diagnosis of cancer: an overview

Enhancing the discrimination between tumour and host has been an underlying goal of efforts to improve the diagnosis and treatment of cancer. Over the past 15 years considerable interest has focussed upon targeting systems designed to permit selective delivery of a variety of agents, including drugs, radioisotopes and toxins, to tumours, for both diagnosis and therapy. A vast body of information has accumulated on this subject, and considerable emphasis has been placed on the use of antibodies as carriers, as at present they offer the greatest clinical potential. Many targeting systems have been evaluated in vitro and in pre-clinical models, but few, with the exception of antibody-radioisotope conjugates, have been evaluated in patients. However, systematic evaluation of the therapeutic potential of immunoconjugates in the clinic is planned or already under way. While reviews of some individual aspects of antibody targeting do exist, there are none that encompass this entire field. Our objective is to fill this gap with a concise overview of antibody-mediated targeting for diagnostic and therapeutic applications.

Visualization of metastases from colon carcinoma using an iodine 131-radiolabeled monoclonal antibody

A murine monoclonal antibody that reacts with human colonic cancer (250-30.6) was labeled with radioactive iodine (131I) and the antibody was injected intravenously into 15 patients with known metastases originating from carcinoma of the colon (10 cases), malignant melanoma (1), breast (1), pancreas (1), hepatocellular carcinoma (1), and adenocarcinoma of unknown origin (1). Of the patients with metastatic colon carcinoma, there were 19 known deposits as judged by the techniques of clinical examination, x-rays, and scans obtained using sulpha-colloid. Of these 19 deposits, 17 (90%) were found using the 131I-labeled monoclonal antibody. In one case, the primary tumor, previously undiagnosed, was found. In only 1 of the 10 patients was tumor not found and this was due to the subsequent finding that the undifferentiated tumor did not react with antibody. Of the five patients who did not have carcinoma of the colon, three had negative scans, but two were positive. Thus, the technique of immunoscintography can readily detect both primary and metastatic tumors.

Monoclonal antibodies in cancer treatment: where do we stand after 10 years?

Monoclonal antibodies (MoAbs) with specificity to tumour-associated antigens have become increasingly available during the past years. Presently, they are being applied in various in vitro diagnostic assays. They have contributed to the knowledge of cancer biology to a large extent. The understanding of cell surface characteristics and antigenic phenotype of tumours has in particular influenced the approach in the treatment of leukemias and lymphomas. From successful tumour localization in patients by gamma-emitting radio-labelled MoAbs it became clear, that these proteins offer a unique possibility to target therapeutic agents to tumour sites. The mere administration of MoAbs did not result in sufficient clinical benefit, but with proper precautions high doses of murine antibody were well tolerated. In order to use MoAbs as a carrier system, various toxins, cytostatic drugs, or radionuclides have been conjugated to these proteins. Thus far, specific problems were encountered not only associated with the immunoconjugate itself, but also to its fate in the patient. With regard to the substantial knowledge on the use of MoAbs in vivo obtained from animal tumour models, immunoscintigraphy in patients, and phase I serotherapy trials, we will undoubtedly determine the optimal conditions required for a conjugated anti-tumour agent to achieve enhanced cytotoxicity without increased side-effects. Preliminary results with high doses of 131I-labelled MoAbs in patients having tumour lesions expressing relevant antigens encourage further studies with immunoconjugates in cancer treatment. While much work needs to be done to further define the role of MoAbs as a new treatment modality in malignancies, this area of immunotherapy deserves great emphasis for the development of effective conjugates for future patients.