Profiling human gene expression with cDNA microarrays.

As a result of genomics initiatives worldwide, it has become increasingly easy to obtain cDNA clones representing the 3 ends of many human genes. This unit describes methods that allow these clones to be used as hybridization detectors in a highly parallel assay of gene expression. Protocols are provided for preparing cDNA microarrays, extracting RNA from cells of interest and preparing fluorescently labeled cDNA representations of the message pools, and hybridizing the labeled cDNAs to the microarrays.

Profiling human gene expression with cDNA microarrays.

As a result of genomics initiatives worldwide, it has become increasingly easy to obtain cDNA clones representing the 3' ends of many human genes. This unit describes methods that allow these clones to be used as hybridization detectors in a highly parallel assay of gene expression. Protocols are provided for preparing cDNA microarrays, extracting RNA from cells of interest and preparing fluorescently labeled cDNA representations of the message pools, and hybridizing the labeled cDNAs to the microarrays.

Molecular classification of cutaneous malignant melanoma by gene expression profiling.

The most common human cancers are malignant neoplasms of the skin. Incidence of cutaneous melanoma is rising especially steeply, with minimal progress in non-surgical treatment of advanced disease. Despite significant effort to identify independent predictors of melanoma outcome, no accepted histopathological, molecular or immunohistochemical marker defines subsets of this neoplasm. Accordingly, though melanoma is thought to present with different 'taxonomic' forms, these are considered part of a continuous spectrum rather than discrete entities. Here we report the discovery of a subset of melanomas identified by mathematical analysis of gene expression in a series of samples. Remarkably, many genes underlying the classification of this subset are differentially regulated in invasive melanomas that form primitive tubular networks in vitro, a feature of some highly aggressive metastatic melanomas. Global transcript analysis can identify unrecognized subtypes of cutaneous melanoma and predict experimentally verifiable phenotypic characteristics that may be of importance to disease progression.

Radiolabeling of monoclonal antibodies.

Radiolabeling of monoclonal antibodies (mAbs) is often one of the principal methods for the in vitro and in vivo assessment of these reagents, whether this is determining the affinity of a new reagent, preparing for preclinical testing, or clinically for diagnostic or therapeutic use.

Radioimmunotherapy after chemotherapy compared to chemotherapy alone in the treatment of advanced ovarian cancer: a matched analysis.

Ovarian cancer has an overall five-year survival of around 30% in spite of complete remissions being obtained after optimal surgery and platinum-based chemotherapy. Previous studies have indicated a survival advantage for patients treated with radiolabelled monoclonal antibodies (radioimmunotherapy). We report here on the survival of patients who received single-dose intraperitoneal radioimmunotherapy after having achieved complete remission with standard management. Twenty-five patients with epithelial ovarian cancer, stages Ic-IV, received adjuvant intraperitoneal radioimmunotherapy following completion of conventional chemotherapy. On achieving complete remission they receive once 25 mg of HMFG1 labelled with 18 mCi/m2. Controls for cases were sought from the database of the North Thames ovary group (NTOG). Controls were selected on the basis of stage, histological grade and type, and age of patient at diagnosis. Kaplan-Meier survival plots were constructed for cases and controls and subjected to statistical analysis with the log-rank test. Additionally, using a database of 84 NTOG patients known to be disease-free at the end of chemotherapy, estimated survival curves were constructed using Cox's proportional hazards regression model. Close matches were found for 20 of the 25 patients. Median survival has not been reached at a median follow-up of 59 months for cases and 27 months for controls. Survival at five years is 80% for cases and 55% for controls (p=0.0035). The Cox model estimates long-term (10-year) survival of 70% for patients who received radioimmunotherapy, compared to 32% for those that did not (p=0.003). All patients developed serological evidence of human anti-mouse antibody (HAMA). This study shows a likely survival benefit for patients with ovarian cancer who receive intraperitoneal radioimmuno-therapy in the adjuvant setting.

Anti-chelate antibodies after intraperitoneal yttrium-90-labeled monoclonal antibody immunoconjugates for ovarian cancer therapy.

UNLABELLED: The development of stable chelating agents for metal isotopes (e.g., 90Y) such as CITC-DTPA, a benzyl-analog of DTPA, allowed us to evaluate the efficacy of 90Y-labeled HMFG1 MAb administered intraperitoneally in patients with ovarian cancer. Our previous studies of 90Y-HMFG1 antibody, however, showed that all patients developed anti-chelate antibody responses (to the macrocycle benzyl-DOTA), resulting in clinical side effects in a significant percentage of this group. METHODS: We evaluated the immunogenicity of CITC-DTPA (administered to 12 patients as 90Y-HMFG1-CITC-DTPA after coupling it to HSA using solid-phase ELISA. RESULTS: Eleven of 12 evaluable patients developed anti-CITC-DTPA antibodies. Five patients (approximately 40%) developed hypersensitivity syndrome, most likely due to a type III immune reaction (serum sickness). Most patients had a low titer of pre-existing anti-chelate response which correlated positively with post-therapy response levels (p = 0.001). IgM anti-CITC-DTPA antibodies developed 2 wk while IgG antibodies developed 3 wk after treatment. Western blot analysis of post-therapy sera revealed a reaction with HSA-CITC-DTPA (60 kDa band) and no reaction with HSA or HSA-DTPA, whereas pre-therapy sera of the same patients were negative to all antigens. CONCLUSION: CITC-DTPA is immunogenic in patients after intraperitoneal administration of 90Y-CITC-DTPA labeled MAbs. Self-limiting clinical side effects consistent with a serum sickness-like immune reaction were observed in 5 of 12 patients.

Direct technetium-99m labeling of three anticancer monoclonal antibodies: stability, pharmacokinetics and imaging.

UNLABELLED: Monoclonal antibodies (MAbs) directly labeled with 99mTc have been used in a number of clinical immunoscintigraphic investigations. Three anti-cancer MAbs were radiolabeled with 99mTc using a reduction-mediated technique. The stability, biodistribution and in vivo pharmacokinetics were assessed and compared with the same antibodies labeled with 125I. METHODS: Immunoreactivity data were obtained by ELISA and RIA. Homogeneity and stability of radiolabeled antibodies (in vitro and in vivo) were measured by size-exclusion, fast protein liquid chromatography and SDS-PAGE. Pre-clinical, in vivo investigations utilized the nude mouse/HEp2 xenograft model, and clinical imaging and pharmacokinetic data were obtained from patients with confirmed or suspected lesions. RESULTS: Both 99mTc- and 125I-labeled antibodies were shown to be homogeneous and stable, although 99mTc-labeled antibody fragments were detected by SDS-PAGE. Pharmacokinetic studies in patients revealed a significant difference in the clearance rates between 99mTc- and 125I-labeled antibodies, with those labeled with 99mTc having a shorter biological half-life, indicating that the 99mTc-labeled antibodies may be less stable than the iodinated ones. Nevertheless, specific tumor localization was successfully demonstrated in nude mice bearing a human tumor xenograft using 125I- and 99mTc-labeled H17E2 antibody. Furthermore, in the clinic, using 99mTc-labeled HMFG1 and 1A3, successful imaging was achieved in 12 out of 19 patients with lesions for which these antibodies were specific. CONCLUSION: Anticancer MAbs radiolabelled using this reduction-mediated technique are suitable agents for clinical, immunoscintigraphic investigations.

Tc-99m-labeled nonspecific polyclonal human immunoglobulin G is taken up by malignant tumors.

A new agent originally introduced for localizing inflammatory lesions is Tc-99m human immunoglobulin G (HIG). Recently, focal uptake of this agent was seen in malignant lesions in a limited number of patients during inflammation imaging studies. In this prospective clinical study, the authors aimed to evaluate the uptake of Tc-99m HIG in malignant lesions. Nineteen patients with histopathologically proven malignant tumors were studied (seven had distant metastases, the primary tumor was surgically removed in two). There was no evidence of inflammation or infection in any patient. The authors imaged patients at 1, 4, and 24 hours after injection. The dose was 15-20 mCi (555-740 MBq). Focal uptake was detected in the primary tumor in six patients and in the metastases in five patients, raising some question about the specificity of Tc-99m HIG imaging for the detection of inflammation and infection.

Expression of the c-erbB-3 protein in gastrointestinal tract tumours determined by monoclonal antibody RTJ1.

We have examined the expression of the c-erbB-3 protein in a wide range of tumours of the gastrointestinal (GI) tract using immunocytochemical staining. Two antibodies were employed, a polyclonal antibody, 49.3, and a new monoclonal antibody, RTJ1, both raised to a synthetic peptide from the cytoplasmic domain of the human c-erbB-3 protein. The antibodies recognize c-erbB-3 by immunoprecipitation and Western blotting of lysate prepared from a cell line engineered to overexpress the protein. Both antibodies also detect expression of the protein in formalin-fixed, paraffin-embedded human tissues. The RTJ1 monoclonal antibody gave superior staining, showing lower background and more pronounced cell surface immunoreactivity. The c-erbB-3 protein was found in normal epithelial cells throughout the GI tract, in squamous epithelium of the oropharanyx and oesophagus, in the parietal cells of the stomach, and in the surface enterocytes of the small and large bowel. Seventy-six tumours arising at these sites were examined for c-erbB-3 protein expression. Widely varying levels of expression were seen, from absent to intense staining with cell membrane accentuation.

Technetium-99m-labeled antibodies. Stability compared to 125I labeled antibodies.

It is essential in any method for radiolabeling antibody with 99mTc that the labeling procedure is rapid and reliable, producing a highly stable 99mTc-antibody complex with minimal effect on the immunoreactivity of the antibody. In the present study, analysis of the stability and homogeneity of radiolabeled (99mTc and 125I) antibodies (HMFG1 and PR1A3) was carried out by fast protein liquid chromatography (FPLC) using superose-6 and S-200 columns, and by polyacrylamide gel electrophoresis (PAGE) followed by autoradiography. Superose 6 and S-200 gel filtration analysis showed the radiolabel (99mTc or 125I) eluting with a retention time identical to that of native antibody. No peaks of relative molecular size (Mr) corresponding to possible antibody fragments were seen in either the UV or the radioactive FPLC elution profiles. PAGE analysis of 99mTc labeled antibody, however, revealed the presence of a number of radiolabeled antibody fragments (Mr < IgG) that were not detected by the same analysis of 125I labeled antibody. The stability of the radiolabeled antibodies in serum in vitro was also studied. FPLC (superose-6) analysis after 45 h incubation in normal serum in vitro revealed 3.3% (HMFG1), and 20% (PR1A3) of the 99mTc on a molecule or aggregate with a Mr greater than that of IgG. There is also the appearance of small amounts of 99mTc-labeled material with a Mr < IgG in the later fractions (2.2% for HMFG1 and 4.9% for PR1A3). Similar results were obtained using radioiodinated antibody, although the small amount of low molecular size material detected as a single peak with a longer retention time than the 99mTc equivalent corresponds to free iodide.

Development of humoral immune responses against a macrocyclic chelating agent (DOTA) in cancer patients receiving radioimmunoconjugates for imaging and therapy.

The development of stable immunoconjugates by the advent of macrocyclic metal chelating agents (DOTA) has enabled us to study the ability of 111In-DOTA-labeled monoclonal antibodies to detect tumor lesions in a pilot radioimmunolocalization study, as well as to evaluate the kinetics, toxicity, and efficacy of i.p. administered 90Y-DOTA-labeled murine monoclonal antibody in a Phase I/II clinical trial of advanced ovarian cancer. The development of serum sickness-like reactions in three of six treated patients, in the absence of previous monoclonal antibody administration, led us to study the potential immunogenicity of the new chelate. Six patients with ovarian cancer received 25 mg of HMFG1 monoclonal antibody coupled with 90Y-DOTA (doses of radioactivity, 15 to 25 mCi), administered i.p. Eight patients with various malignant tumors received low doses (220 micrograms to 1 mg) of monoclonal antibodies, labeled with 111In-DOTA, i.v. for imaging studies. Using a solid-phase enzyme-linked immunosorbent assay method, the immunogenicity of DOTA was evaluated. Serial dilutions of patients' sera, before and after imaging or therapy with DOTA-coupled monoclonal antibodies, as well as sera from patients who did not receive DOTA-coupled antibody, were screened on enzyme-linked immunosorbent assay plates coated with human serum albumin (HSA), HSA-2-iminothiolane, and HSA-2-iminothiolane-benzyl-DOTA. All patients treated with i.p. monoclonal antibody developed anti-DOTA antibodies. Four of eight patients who received i.v. "imaging" doses of DOTA-coupled monoclonal antibody developed antibodies against DOTA. The levels of anti-DOTA response correlated with the amount of injected radioimmunoconjugate (r = 0.889, P less than 0.001). None of the patients who received DOTA-coupled antibody had detectable antibodies against the macrocycle before immunoconjugate administration. We then addressed further the restriction of the immune response against the macrocycle. We found that there was no or very low response against the aromatic ring attached to DOTA. Most, if not all, of the immune response is directed against the DOTA ring structure. Affinity purification of anti-DOTA antibody from serum enabled quantitation of these antibodies in the serum of patients. An inverse, statistically significant correlation was observed between the percentage of binding inhibition of a patient's serum to DOTA, by HSA-2-iminothiolane-DOTA (100 micrograms/ml) and the level of anti-DOTA immunoglobulin in the serum.(ABSTRACT TRUNCATED AT 400 WORDS)

Tumour localisation with a radioactively labelled reshaped human monoclonal antibody.

A genetically reshaped human IgG1 monoclonal antibody (Hu2PLAP) with anti-tumour specificity, was radiolabelled with Indium-111 by chelation with a new macrocyclic compound (DOTA) which allows the production of stable radioimmunoconjugates for in vivo application. This was used to image seven patients with malignant disease, of whom two had been previously exposed to mouse monoclonal antibodies and had developed human anti-mouse antibodies (HAMA). Successful tumour localisation was seen in the four patients with active disease and antigen positive tumours. No patient showed any antibody responses against Hu2PLAP, but three out of six patients tested showed an immune response against the macrocycle DOTA. Reshaped human monoclonal antibodies with anti-tumour specificity may facilitate repeated administrations of radioactive antibodies, thus allowing new possibilities, both in the diagnosis and treatment of cancer.

Distribution of intestinal mast cell proteinase in blood and tissues of normal and Trichinella-infected mice.

A sensitive and specific enzyme-linked immunosorbent assay (ELISA) was developed for mouse intestinal mast cell proteinase (IMCP). Specificity was demonstrated by the absence of immunoreactivity with extracts of isolated serosal mast cells (SMC), or with high concentrations (50 micrograms/ml) of the antigenically similar rat mast cell proteinases I or II. The small and large intestines in normal mice were the major sources of IMCP, there being little or no IMCP in non-mucosal tissues. Concentrations of IMCP in normal (non-parasitized) mice were low, but were increased 100-1000-fold intestines of mice infected 10 days earlier with Trichinella spiralis. The kinetic response of secreted IMCP into the blood of mice following infection with T. spiralis was also studied. Systemic release of IMCP coincided with the immune expulsion of adult worms from the intestine, and peak concentrations (9.45 micrograms/ml IMCP) occurred 9 days after infection. The tissue distribution of IMCP, its secretion into blood, and its enteric accumulation during parasite infection, are consistent with a mucosal mast cell (MMC) source for IMCP. The results are discussed in the context of similar findings for rat mast cell proteinase II.