Localisation of lung cancer by a radiolabelled monoclonal antibody against the c-myc oncogene product

Side-Effects of Monoclonal Antibody Infusions for the Diagnosis and Treatment of Cancer

This literature review presents an inventory of the nature and incidence of side-effects that arise from the clinical application of monoclonal antibodies (MoAb) for the diagnosis and treatment of cancer. Most side-effects occurred during therapy. Toxic reactions, such as fever, sweating and chills, were more common than immunological skin reactions; they were observed predominantly in association with the elimination of circulating target cells. Dosage and rate of administration of the MoAb appeared to have little influence on the reactions, which disappeared quickly and did not necessitate discontinuation of treatment. Serum sickness, anaphylactic reactions and bronchospasms were not common; the patients reacted quickly to the indicated therapy. Prevention of the side-effects described here, especially during diagnostic applications, was such that they need not form a barrier to the clinical use of MoAb.

Clinical aspects of metastases

In the short term the major hope for reducing cancer mortality is to effect a reduction in the number of patients who develop malignant disease and in the proportion of cancer patients who present with metastases. Hitherto the major emphasis of clinical research on metastases has been directed at detection and elimination rather than prevention or early diagnosis. Extensive data relating histological class and tumour stage to risk of metastasis and metastatic pattern have been compiled from studies of relapse and from invasive and non-invasive staging procedures. However, the biological events involved in the metastatic process and the factors which influence it in relation to the natural history of primary human tumours are poorly understood. Information describing metastatic heterogeneity in individual patients, in terms of therapeutic response or intrinsic sensitivity to cytotoxic agents, is scanty. Similarly, the characteristics of human metastases in relation to the clonal heterogeneity of primary tumours are poorly defined. The clinical application of molecular biological techniques, which has led to the association of gene amplification with tumour behaviour in a range of sites, offers the prospects of improved tumour localization and therapy and, in the longer term, of tumour control by interventions based on a knowledge of the mechanisms that regulate cell growth and differentiation.

Radioimmunodetection of malignant solid tumours

An increased clinical utility of radiolabelled monoclonal antibodies (MoAb), recognizing a variety of different antigens expressed preferentially in malignant tissue, for localizing primary, metastatic and recurrent cancer has been documented in many recent investigations. This review focuses on both basic and practical aspects of radioimmunodetection in oncology and is a status report on the performance and limitations of radiolabelled antibody procedures currently applied to the clinical detection of malignant solid tumours. At this time clinically validated radioimmunodetection methods are available for colorectal, ovarian, breast, lung, thyroid medullary, and head and neck carcinoma, and melanoma. Recent advances in humanization of MoAb significantly improve the prospects of effective antibody-guided radiotherapy in the near future.

Radioimmunodetection of non-small cell lung cancer using technetium-99m-anticarcinoembryonic antigen IMMU-4 Fab' fragment. Preliminary results

BACKGROUND

Although computed tomography and magnetic resonance imaging have improved the staging and evaluation of non-small cell lung cancer (NSCLC), mediastinal staging lacks adequate specificity and sensitivity. Radioimmunodetection may augment computed tomography and magnetic resonance imaging. The authors evaluated the ability of the technetium 99m-anticarcinoembryonic antigen IMMU-4 Fab' fragment to localize NSCLC in vivo, measured its pharmacokinetics, and estimated its radiation dose.

METHODS

Seventeen patients with carcinoembryonic antigen-positive NSCLC received 16-30 mCi of technetium 99m IMMU-4 Fab'. Planar imaging was performed at 1-7 hours and 20-24 hours. Single-photon emission computed tomography (SPECT) was performed within 8 hours after injection. In 10 patients, blood sampling, urine collection, and quantitative imaging were performed to determine blood and urine pharmacokinetics and radiation dose estimates. Human anti-mouse antibody response was measured for as long as 3 months after administration.

RESULTS

Planar and/or SPECT imaging detected 72% of 32 known lesions. SPECT was more sensitive than planar imaging. T1/2 alpha averaged 0.18 +/- 0.33 hours; T1/2 beta averaged 8.02 +/- 5.53 hours. The mean concentration versus time value was 1.11 +/- 0.56 mg.h. The average whole body dose estimated for administration of 30 mCi was 0.45 +/- 0.08 rads. No human anti-mouse antibody responses were detected.

CONCLUSION

The tumor detection rate was high, but the persistent blood pool at < 8 hours complicated image interpretation. An intermediate imaging time point (12-16 hours) might be preferable. SPECT is an important adjunct to imaging with this radioimmunoconjugate. The acceptable dosimetry estimated for 30 mCi Technetium 99m IMMU-4 Fab' and the lack of human anti-mouse antibody responses suggest this is a promising localizing tool for NSCLC:

Detection of increased amounts of the extracellular domain of the c-erbB-2 oncoprotein in serum during pulmonary carcinogenesis in humans

Over-expression of the c-erbB-2 oncogene-encoded p185 protein product has been implicated in the pathogenesis of a wide variety of human malignancies, including lung cancer. Over-expression of p185 can be detected immunologically by quantification of the extracellular domain of p185 (c-erbB-2 oncopeptide) in extracellular fluid in vitro and in serum in vivo. An enzyme-linked immunosorbent assay (ELISA) for the c-erbB-2 oncopeptide was used to examine banked serum samples of 11 pneumoconiosis patients who subsequently developed lung cancer and serum samples from 11 hospital controls matched for age, sex, ethnic group and smoking as well as 55 unmatched general population controls. The mean serum level for the c-erbB-2 oncopeptide in human neu units/ml in the lung cancer cases (1,756 +/- 549 HNU/ml) was statistically significantly elevated (p < 0.001) in comparison to the mean level in the matched controls (976 +/- 488 HNU/ml) or the general population controls (888 +/- 655 HNU/ml). Defining a positive elevation of the serum c-erbB-2 oncopeptide as any value more than 2 standard deviations above the mean of the matched controls, 64% (7 of 11) of the lung cancer cases were positive compared to 0% (0 of 11) matched controls and 5% (3 of 55) of the unmatched controls. In addition, 4 of the 7 c-erbB-2 oncopeptide-positive cancer cases had positive serum samples prior to the time of disease diagnosis (average = 35 months). These results suggest that serum c-erbB-2 oncopeptide may be elevated at an early stage of pulmonary carcinogenesis and that further prospective study of the utility of this biomarker is warranted.

Conventional Antibodies: Requirements and Methods for their Optimization

Eighteen years after the discovery of monoclonal antibodies (MAbs), the debate as to whether these reagents have fulfilled their promise must now be addressed. When MAbs were studied as tools for diagnosis and therapy, problems arose regarding the reagents themselves and the recognized target antigens. Because most MAbs are of murine origin, they usually evoke an immune response in human patients, which reduces their effectiveness. Moreover, their bulky size and dispersal via the blood prevent most of the injected antibodies from substantially penetrating solid, poorly vascularized tumors. However, MAbs that are adequately selected and manipulated to circumvent these problems have been found to successfully image tumors and to be therapeutically active.

Radioimmunoimaging of non-small cell lung cancer with 111In- and 99mTc-labeled monoclonal anti-CEA-antibodies

Radiolabeled monoclonal anti-CEA antibodies were used for radioimmunolocalization (RIL) of non-small cell lung cancer; in 30 patients with 111In labeled anti CEA F(ab')2 fragment (BW 431/31) and in 16 with 99mTc-labeled intact MoAb (BW 431/26). RIL results were compared with those of other imaging modalities. Paraffin sections from some patients were also studied immunohistochemically using anti-CEA antibody. Patients with 111In labeled MoAB were imaged twice 1-4 days after injection and for image enhancement pulmonary and liver/spleen subtraction were performed. Twenty-seven of 28 primary tumors were positive and metastases were detected in all patients. The total number of lesions was 78 of which 61 (78%) could be detected by RIL. For verification CT was applied to the study of 46 lesions detected by RIL. We found 6 unknown lesions subsequently verified histologically. Using subtraction techniques we detected 9 lesions in 4 patients, later verified as pulmonary metastases, not detected in unprocessed images. Pleural, mediastinal and pericardial lesions were also better delineated in subtracted images than in unprocessed images. Imaging of non-small cell lung cancer with 99mTc-labeled MoAB was performed twice 4-24 h after injection. RIL results were compared with other imaging methods; CT US, conventional radiography, and immunohistochemistry. Twelve out of 16 patients with suspected or known lung cancer had positive immunoscintigrams; 19 of 25 lesions could be detected by RIL. There were 5 false positive and 2 true negative findings. Immunoperoxidase (IP) stainings of paraffin sections of the tumours from 7 patients were performed using two different anti-CEA antibodies; BW 431/26 and ZCEA1. None of the seven tumors examined by immunohistochemistry were negative when stained by BW 431/26, which was the antibody used for immunoscintigraphy.

Biological monitoring of cancer chemoprevention

A major limiting factor in the successful implementation of cancer chemoprevention trials has been the determination of endpoints to measure efficacy and success. The use of the ultimate goal of such trials, namely, cancer incidence, as an endpoint has serious feasibility problems, including the need for large numbers of participants, long follow-up periods, and high costs. The application of biological markers as intermediate endpoints to reveal responses to chemopreventive agents within a short time and to act as surrogates for cancer is an attractive concept worthy of intense investigation. This study reviews some potential biological markers, including genetic, cellular, biochemical, and immunological, as well as their possible application to cancer chemoprevention.

Detection of a novel marker in the bronchial secretions of patients with non-small cell lung cancer using the 4B5 monoclonal antibody

A murine monoclonal antibody designated 4B5 was raised against the high molecular weight fraction of pooled sputum from patients with non-small cell lung cancer (NSCLC). Immunohistochemical staining indicated that 4B5 binds to histologically normal bronchial epithelium distant from tumor in 72% (39 of 54) of patients with NSCLC, but it binds to the primary cancer in only 13% (7 of 54) of the same patients. The antibody reacted less intensely with the bronchial epithelium in 16.6% (3 of 18) of autopsied patients without significant lung disease. The antigen recognized by 4B5 is a high molecular weight glycoprotein of more than 400 kilodaltons, judged by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blot analysis. Antigenic activity persisted after heating and resisted treatment with neuraminidase, but it was destroyed using protease and periodate. Multiple epitopes were present on each molecule recognized by 4B5. The determinants recognized by this antibody deserve additional study as possible markers of premalignant change in patients with NSCLC.

The effect of circulating antigen and radiolabel stability on the biodistribution of an indium labelled antibody

This study has investigated two of the main problems with radiolabelled antibody imaging, the formation of circulating immune complexes (I.C.) and the non specific binding of radiolabel to the antibody molecule. Patients undergoing immunoscintigraphy with 111In labelled monoclonal antibody ICR2 were divided into three groups who received either the radiolabelled antibody alone (control, n = 12), the radiolabelled antibody which was incubated with the chelating agent diethylene triamine pentacetic acid (DTPA) prior to size exclusion chromatography (n = 6) or whose injectate was treated with DTPA and cold MAb administered intravenously prior to radiolabelled MAb administration (n = 6). Radiolabelled antibody uptake in abdominal organs was measured by region of interest analysis using a gamma camera with online computer and that in tumour and normal tissues by gamma well counting of biopsies. Circulating antigen and immune complex was measured by high pressure liquid chromatography (HPLC). The sensitivity of tumour imaging and the tumour uptake of radiolabelled antibody was not significantly different between the groups. Patients with high circulating antigen levels developed high levels of circulating immune complex but also had high tumour uptakes of radiolabelled antibody. Administration of cold MAb increased the splenic, but did not effect the tumour uptake of radiolabelled antibody and only minimally reduced levels of circulating immune complex. Chelate administration reduced the urinary excretion of radioactivity but increased the liver uptake of radioactivity. These results have shown that successful antibody imaging can be carried out despite high levels of circulating antigen, that large doses of unlabelled antibody are required to prevent immune complex formation and that removal of non specifically bound 111In does not reduce the liver uptake of radioactivity.

Accessibility to intracellular antigens within nutritionally deprived human mammary epithelial cells

We have previously demonstrated immunolocalization of antikeratin antibodies in apparently random subpopulations of malignant cells in fresh surgical specimens of breast carcinoma (S. H. Dairkee and A. J. Hackett, 1988, J. Natl. Cancer Inst. 80, 1216-1220). The goal of the present study was to determine whether deficiencies in essential nutrients contribute toward cellular alterations in membrane integrity, consequently allowing antikeratin to bind to the cytoskeleton within live, unfixed cells. We have demonstrated here that in an in vitro model in which human mammary epithelial cells are subjected to an oxygen-glucose gradient, immunolocalization of antikeratin within the cells is observed in a dose-dependent manner in the depleted regions of the gradient, even though the cells appear to be morphologically unaltered. The potential use of antibodies to intracellular antigens for immunotargeting solid tumors and the use of this method in antibody-loading studies toward understanding functional aspects of specific cellular antigens, as well as determining differential response of various cell types under these culture conditions, are discussed.

Inhibition of the hepatocyte uptake of radiolabelled monoclonal antibodies by chelating agents

The imaging of small abdominal tumours with indium 111 labelled monoclonal antibodies (MAbs) is often obscured by the uptake of activity into the heptocytes of normal liver tissue. A model has therefore been developed to analyse reagents which may inhibit the hepatocyte uptake of 111In-MAb whilst preserving tumour uptake. Primary rat hepatocyte cultures and an epithelial membrane antigen (EMA) expressing tumour cell line (MCF7), recognised by the EMA-specific MAb ICR2, were obtained in tissue culture. Monolayers of both cells were incubated with the 111In-MAb with or without the additional reagents and the cell uptake then measured and expressed per milligram of cell protein using a Lowry protein assay. No preferential reduction in hepatocyte uptake was noted by incubating cells with either saturated or unsaturated transferrin. The chelating agent, diethylene triamine penta-acetic acid (DTPA), however, significantly reduced the uptake of activity in hepatocytes but not the tumour cell line (P less than 0.05). An optimum concentration and time period for incubating DTPA with labelled MAb was established. The mean hepatocyte uptake was reduced by 80% with a 1 h incubation with 1 mM DTPA. These results suggest that DTPA may have a role in reducing the liver uptake of radioactivity in patient studies using 111In-MAb.

Immunoscintigraphy of human lung squamous cell carcinoma using an iodine-131 labelled monoclonal antibody (Po66)

Monoclonal antibody (McAb) Po66 has been obtained by immunisation of mice against a human lung squamous cell carcinoma. The in vitro reactivity of the antibody with cancer cells and its ability to localise in human lung cancer xenografts growing in nude mice have been reported earlier. Presented here is the first clinical evaluation of the antibody for scintigraphic detection of tumours. Thirty-three patients with histologically confirmed primary non-small cell lung carcinoma were investigated. Twenty-seven of them were explored at the preoperative stage and six at 6 months after surgery. Biodistribution results were obtained from seven operated patients by combining injections of 131I-radiolabelled Po66 and of 125I-labelled unrelated immunoglobulin. The localisation index was three times higher for this specific antibody. Immunoscintigraphy detected 78% of primary tumours and 100% of recurrences. In this short series of patients, immunoscintigraphy proved helpful in the assessment of tumour spread in four patients by visualising localisations in the mediastinum or the contralateral lung which the CT scan had failed to demonstrate. Immunoscintigraphy was also more efficient than plain chest X-ray for the detection of local tumour recurrences.

The role of tumor markers in the early detection of cancer

Tumor markers include a broad range of substances expressed at different levels and in different biochemical forms. Bence-Jones protein, carcino-embryonic antigen and alpha-fetoprotein are recognized as some of the earlier utilized markers. Recent technologic advances have led to the development of a variety of serum tumor markers, tumor markers in body fluids, tissue tumor markers, and genetic tumor markers, such as protooncogenes.

Oncogenes and onco-suppressor genes: their involvement in cancer

We review the involvement of two groups of genes, oncogenes and onco-suppressor genes, in malignant transformation. Approximately 40 oncogenes have been described mainly through studies on retroviruses and by in vitro functional analyses such as transfection of transforming genes into 'normal' cells. Because they are more difficult to identify, only a handful of onco-suppressor genes have been described so far, but potentially they could number as many as oncogenes. Where these genes have been isolated and sequenced, they have been shown to be highly conserved among species, suggesting that these genes play an essential role in the normal cell. Although some of properties of oncogenes have been identified, we do not know in detail the role these genes play in normal cells or how genetic damage contributes to malignancy. The effect of oncogene expression on a cell depends both on the cell type and on the oncogene, and in some circumstances oncogenes act as onco-suppressor genes and vice versa. The elucidation of the mechanism of action of oncogenes and onco-suppressor genes will not only increase our understanding of these important genes but might also provide the framework for a biological approach to the treatment of cancer.

Oncogene expression in ovarian cancer: a pilot study of c-myc oncoprotein in serous papillary ovarian cancer

The nuclear-associated protein product of the c-myc gene, p62c-myc, was assayed simultaneously with total DNA using flow cytometry in nuclei extracted from archival biopsies of serous papillary carcinoma of the ovary. The oncoprotein was probed with a synthetic peptide-induced mouse monoclonal antibody which was subsequently labeled with a fluorescent rabbit anti-mouse immunoglobulin and DNA was assayed using the nucleic acid fluorochrome propidium iodide. Serous papillary ovarian carcinoma expressed significantly higher p62c-myc levels compared with normal ovary (P less than 0.00003 Mann-Whitney U test). Biopsies classified as "borderline" low-potential malignancy exhibited levels between normal ovary and carcinoma. The difference between normal and "borderline" was significant at P less than 0.003, but no difference between "borderline" and frankly invasive biopsies was observed, P = 0.149. There was no difference among the histological grades of carcinomas. All normal ovaries had diploid DNA content as did 5/6 cases of "borderline" malignancy. The majority of cases of carcinoma, 28/36, were aneuploid. There was a statistically significant difference in the distribution of aneuploidy, P less than 0.005, between invasive carcinomas and those classified as "borderline" low-potential malignancy.

Flow cytometric quantitation of the c-myc oncoprotein in archival neoplastic biopsies of the colon

The c-myc oncogene encoded protein product, p62c-myc, was assayed simultaneously with DNA in populations of individual nuclei extracted from archival biopsies of colonic neoplasia. Both the protein and DNA were assayed fluorimetrically using flow cytometry with a synthetic peptide induced monoclonal antibody (MYC 1-6E10) for the protein and propidium iodide for DNA. The nuclear p62c-myc levels increased progressively from normal mucosa through polyps to carcinomas. However, there was a trend for the more poorly differentiated carcinomas to exhibit lower levels than moderately and well-differentiated tumours, p = 0.085. These results agree with those published previously with the same antibody using Western blotting for protein extracted from fresh frozen tissue and immunocytochemical assessment. Furthermore, flow cytometry is able to effect discriminations between subsets in heterogeneous populations using DNA as a second parameter which Western blot bulk studies cannot.

A novel tumour marker related to the c-myc oncogene product

We have studied the utility of the c-myc oncogene product as tumour marker using a set of monoclonal antibodies raised against synthetic peptides constructed from sequence data of the human c-myc oncoprotein. One antibody, Myc1-9E10, raised against the C-terminal 32 amino acids, has been shown to detect specifically the 62 kDa c-myc gene product in tumour cells. Immunoblotting of sera and urine with this antibody consistently revealed a single 40 kDa band (p40). Quantitative analysis using dilution dot immunoblotting demonstrated a considerable increase in the titre of p40 in the sera of 51 patients with a wide range of advanced solid tumours when compared with 17 healthy controls and 50 patients with non-malignant diseases. Serial measurement of the p40 titre in 12 patients with resected colorectal carcinoma shows a gradual return to normal with a half-life of 7 days. Our data suggests that p40 may be a useful new marker for monitoring tumour activity.

Cancer genes: their clinical potential

The central problem in cancer therapy is the poor selectivity of current systemic agents against the common solid tumours. The demonstration that unique segments of DNA, constant in location and conserved in evolution, are involved in growth control opens new avenues for basic and clinical research. The functions of the products of these oncogenes need to be elucidated. Examples of growth control functions include homology to growth factors, surface receptors, protein kinases and cell cycle control proteins. From DNA sequence data peptides predicted to be exposed within intact molecules have been constructed and used to produce monoclonal antibodies to oncogene products. Such antibodies have demonstrated the intracellular localisation of oncogene products and their cell cycle regulatory role. A battery of antibodies against the different oncogene products can be used to aid diagnosis and prognosis. Immunohistology and other methods permit the geographical and quantitative analysis of oncoprotein function in normal and neoplastic tissues. New tumour marker systems have been uncovered. Furthermore, by purification and biochemical analysis the molecular basis for the action of these proteins can be elucidated. It is likely that by the end of the decade new drugs that inhibit oncoprotein function will be available for clinical trial.