Reactivity of B72.3 with adenocarcinomas. An immunohistochemical study of 476 cases

A 3E8.scFv.Cys-IR800 Conjugate Targeting TAG-72 in an Orthotopic Colorectal Cancer Model

PURPOSE

Optical surgical navigation (OSN) will be a potent tool to help surgeons more accurately and efficiently remove tumors. The purpose of this study was to evaluate a novel humanized 3E8 antibody (3E8 MAb) fragment site-specifically conjugated with IR800, 3E8.scFv.Cys-IR800, as a potential OSN agent to target colorectal adenocarcinoma.

PROCEDURES

An engineered single-chain variable fragment of 3E8 MAb (targeted to TAG-72), appending a C-terminal cysteine residue (3E8.scFv.Cys), was created and reacted with IRDye800-maleimide. 3E8.scFv.Cys-IR800 identity and purity were verified by MALDI-TOF mass spectra and 800 nm detected size exclusion column HPLC. In vitro human colon adenocarcinoma LS-174 T cells binding and competition assay validated biological functionality. We further evaluated the imaging ability and receptor-specific binding of 3E8.scFv.Cys-IR800 in an orthotopic LS-174 T mouse model.

RESULTS

A 1:1 dye to protein conjugate was achieved at greater than 90 % HPLC purity. A 1 nmol dose of 3E8.scFv.Cys-IR800 via intraperitoneal injection administration was sufficient to produce high tumor to background fluorescence contrast. Blocking competition studies both in vitro and in vivo using a different blocking protein, 3E8ΔCH2, demonstrated 3E8.scFv.Cys-IR800 binding specificity for TAG-72 antigen.

CONCLUSIONS

3E8.scFv.Cys-IR800 shows properties useful in a clinically viable OSN agent for colorectal cancer.

Mammary Fetal Gland: Identification of New Oncofetal Antigens by Monoclonal Antibodies B72.3, MM1.80 and 4.36

Aims and Background

The B72.3, MM1.80 and 4.63 monoclonal antibodies directed against tumor-associated antigens react in human breast also with metaplastic, preneoplastic and metastatic cells, whereas they do not react with normal adult mammary tissue. The aim of our study was to point out the expression of these antigens during mammary gland development, since tumor-associated antigens are known to represent antigens of differentiation.

Study design

Fifty female fetal breasts between 20 and 40 weeks of gestational age were studied.

Results

Mammary tissue was identified only in 15 cases. B72.3, MM1.80 and 4.36 monoclonal antibodies reacted with epithelial antigens and maintained the same location and intensity in the various gestational ages. Immunoreactivity was weak, cytoplasmic and widespread for the 4.36 monoclonal antibody, intense and cytoplasmatic in a large number of cells for the B72.3 monoclonal antibody, and intense and luminal for the MM1.80 monoclonal antibody.

Conclusions

Such data further support the hypothesis that the normal process of development and differentiation can occur during tumor progression processes. Identification of these new oncofetal markers could offer a new perspective able to recognize the different phases of neoplastic progression and could be useful for prevention.

Novel DNA Polymer for Amplification Pretargeting

In this Letter, different from conventional pretargeting, an additional novel DNA polymer with multiple copies of a target was first designed to be administrated between the antitumor antibody, and the labeled effector served as an amplification pretargeting strategy. Two phosphorothioate DNA strands, a bridging and a target strand, were hybridized to form a polymer. Polymer size, as a function of molar ratios, was then monitored by size exclusion HPLC and electrophoretic mobility shift assay. Moreover, binding efficiency of polymers with the radiolabeled effector and polymer size after hybridization were measured by HPLC as well. As the polymer was expected to produce more binding sites that would be targeted by effectors, amplification pretargeting can greatly improve accumulation of effectors in tumor. This novel proof-of-concept was then well demonstrated by the in vitro test of signal amplification in antibody-binding protein L coated plate and LS174T cells. Compared to conventional pretargeting, significantly increasing radioactive signal was observed in this designed amplification pretargeting, which would serve as a useful paradigm of the potential of oligomer polymers to improve pretargeting and other related approaches.

Role of tumor-associated glycoprotein-72 in the progression of endometrial adenocarcinoma: a proposed study

Endometrial adenocarcinoma is on the basis of the molecular, immunohistological and clinicopathologic features broadly divided into two groups, referred as type I and type II. Type I appears more frequently and in principle patients have a good prognosis; however a significant number of patients develop local recurrences. We hypothesize that TAG-72, expressed on endometrial carcinoma binds and internalizes endocytic pattern recognition receptors on surrounding tissue antigen presenting cells (dendritic cells and macrophages), powers their anti-inflammatory maturation program and make them capable to elicit or modulated tolerogenic immune response mediated by local T and NK effectors. This could support uncontrolled local tumor growth, deeper tumor invasion into surrounding tissues, frequent local recurrences and/or lymph node metastasis. To test this hypothesis, we propose a semi-quantitative immunohistochemical analysis of TAG-72 expression in endometrial adenocarcinoma samples and to correlate the results with clinical and pathological parameters (age, type and histological grade of the tumor, estrogen and progesterone receptor expression, invasion into the myometrium and capillaries, presence of lymph node metastases, FIGO stage, and TNM classification). It would be worthwhile to investigate the local tissue immune response in the tumor environment using tissue samples removed during surgery. These studies could elucidate the underlying immunopathological mechanisms that govern the early recurrence and possibly distant metastases of TAG-72-expressing adenocarcinomas and might help in deciding the type of treatment to be applied in a selected group of cancer patients including application of biological therapy with anti-TAG-72 antibodies, according the principle of personalized oncology treatments.

Site specific discrete PEGylation of (124)I-labeled mCC49 Fab' fragments improves tumor MicroPET/CT imaging in mice

The tumor-associated glycoprotein-72 (TAG-72) antigen is highly overexpressed in various human adenocarcinomas and anti-TAG-72 monoclonal antibodies, and fragments are therefore useful as pharmaceutical targeting vectors. In this study, we investigated the effects of site-specific PEGylation with MW 2-4 kDa discrete, branched PEGylation reagents on mCC49 Fab' (MW 50 kDa) via in vitro TAG72 binding, and in vivo blood clearance kinetics, biodistribution, and mouse tumor microPET/CT imaging. mCC49Fab' (Fab'-NEM) was conjugated at a hinge region cysteine with maleimide-dPEG 12-(dPEG24COOH)3 acid (Mal-dPEG-A), maleimide-dPEG12-(dPEG12COOH)3 acid (Mal-dPEG-B), or maleimide-dPEG12-(m-dPEG24)3 (Mal-dPEG-C), and then radiolabeled with iodine-124 ((124)I) in vitro radioligand binding assays and in vivo studies used TAG-72 expressing LS174T human colon carcinoma cells and xenograft mouse tumors. Conjugation of mCC49Fab' with Mal-dPEG-A (Fab'-A) reduced the binding affinity of the non PEGylated Fab' by 30%; however, in vivo, Fab'-A significantly lengthened the blood retention vs Fab'-NEM (47.5 vs 28.1%/ID at 1 h, 25.1 vs 8.4%/ID at 5 h, p < 0.01), showed excellent tumor to background, better microPET/CT images due to higher tumor accumulation, and increased tumor concentration in excised tissues at 72 h by 130% (5.09 ± 0.83 vs 3.83 ± 1.50%ID/g, p < 0.05). Despite the strong similarity of the three PEGylation reagents, PEGylation with Mal-dPEG-B or -C reduced the in vitro binding affinity of Fab'-NEM by 70%, blood retention, microPET/CT imaging tumor signal intensity, and residual 72 h tumor concentration by 49% (3.83 ± 1.50 vs 1.97 ± 0.29%ID/g, p < 0.05) and 63% (3.83 ± 1.50 vs 1.42 ± 0.35%ID/g, p < 0.05), respectively. We conclude that remarkably subtle changes in the structure of the PEGylation reagent can create significantly altered biologic behavior. Further study is warranted of conjugates of the triple branched, negatively charged Mal-dPEG-A.

Application of immunohistochemistry in the diagnosis of epithelioid mesothelioma: a review and update

A large number of immunohistochemical markers that can assist in the differential diagnosis of epithelioid mesotheliomas are currently available. Because these markers are expressed differently in the various types of carcinomas that can metastasize to the serosal membranes and can potentially be confused with epithelioid mesothelioma, their selection for inclusion in a diagnostic panel largely depends on the differential diagnosis, as well as on which ones work the best in a given laboratory. Traditionally, the panels used in the differential diagnosis of epithelioid mesothelioma have consisted of a combination of positive mesothelioma markers and broad-spectrum carcinoma markers. At present, a wide variety of organ-associated carcinoma markers such as thyroid transcription factor-1 and napsin A for the lung, PAX 8 and PAX 2 for the kidney, and Müllerian-derived tumors; gross cystic disease fluid protein-15 and mammaglobin for the breast; and CDX2 for intestinal differentiation are available, which can assist in establishing the site of origin of an adenocarcinoma when included in a diagnostic panel. This article provides updated information on the composition of the panels of markers recommended in the various differential diagnoses.

Selecting Potential Targetable Biomarkers for Imaging Purposes in Colorectal Cancer Using TArget Selection Criteria (TASC): A Novel Target Identification Tool

Peritoneal carcinomatosis (PC) of colorectal origin is associated with a poor prognosis. However, cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy is available for a selected group of PC patients, which significantly increases overall survival rates up to 30%. As a consequence, there is substantial room for improvement. Tumor targeting is expected to improve the treatment efficacy of colorectal cancer (CRC) further through 1) more sensitive preoperative tumor detection, thus reducing overtreatment; 2) better intraoperative detection and surgical elimination of residual disease using tumor-specific intraoperative imaging; and 3) tumor-specific targeted therapeutics. This review focuses, in particular, on the development of tumor-targeted imaging agents. A large number of biomarkers are known to be upregulated in CRC. However, to date, no validated criteria have been described for the selection of the most promising biomarkers for tumor targeting. Such a scoring system might improve the selection of the correct biomarker for imaging purposes. In this review, we present the TArget Selection Criteria (TASC) scoring system for selection of potential biomarkers for tumor-targeted imaging. By applying TASC to biomarkers for CRC, we identified seven biomarkers (carcinoembryonic antigen, CXC chemokine receptor 4, epidermal growth factor receptor, epithelial cell adhesion molecule, matrix metalloproteinases, mucin 1, and vascular endothelial growth factor A) that seem most suitable for tumor-targeted imaging applications in colorectal cancer. Further cross-validation studies in CRC and other tumor types are necessary to establish its definitive value.

Pretargeting CWR22 prostate tumor in mice with MORF-B72.3 antibody and radiolabeled cMORF

PURPOSE

We have now applied our MORF/cMORF pretargeting technology to the targeting of CWR22 prostate tumor in nude mice.

METHODS

The antiTAG-72 antibody B72.3 was conjugated with an 18 mer MORF while the cMORF was radiolabeled with (99m)Tc. The specific binding of the antibody to the CWR22 cells was first confirmed in an assay placing the radiolabeled B72.3 antibody in competition with increasing concentrations of native B72.3. Thereafter, a group of four CWR22 tumored mice intravenously received the MORF-B72.3 and, 3 days later, the (99m)Tc-cMORF, and were killed at 3 h postradioactivity injection. The dosage of the labeled cMORF was selected on the basis of previous experience in LS174T tumored mice. As controls, four animals received only the radiolabeled cMORF and another four received only the (111)In-B72.3. The maximum percent tumor accumulation (MPTA) of the labeled cMORF was subsequently determined by a dosage study of labeled cMORF. Both a multipinhole SPECT image and a planar gamma camera image were obtained of a representative mouse.

RESULTS

The CWR22 tumor was confirmed to be TAG-72-positive. The MPTA of the labeled cMORF in the CWR22 tumor was 2.22%ID/g compared to only 0.12%ID/g in control mice without pretargeting. Both the planar and tomographic images confirmed the success of the CWR22 pretargeting.

CONCLUSIONS

The MORF/cMORF pretargeting approach has been successfully applied to tumor targeting of the prostate xenograft CWR22. However, the MPTA in this tumor model is lower than that in the LS174T tumor model investigated earlier, possibly due to a lower tumor blood supply.

Claudin 4 identifies a wide spectrum of epithelial neoplasms and represents a very useful marker for carcinoma versus mesothelioma diagnosis in pleural and peritoneal biopsies and effusions

We evaluated the usefulness of the tight-junction associated protein Claudin 4 (CL-4) in the diagnosis of mesothelioma and mimickers, analyzing biopsies from 454 tumors, including 82 mesotheliomas, 336 carcinomas of different origin (278 primary, 58 metastatic to serosae), 36 nonepithelial spindle cell neoplasms, as well as 97 cytological samples from reactive effusions (12), mesothelioma (23) and metastatic carcinomas (62). CL-4 was consistently negative in normal and reactive mesothelium, as well as in all 82 mesotheliomas. In contrast, strong reactivity was found in 57/58 serosal metastasis, and in 245/278 primary carcinomas, with uppermost expression (150/153) in those most frequently involved in the differential with mesothelioma (lung, breast, gastrointestinal tract, pancreas, ovary, primary serous papillary carcinoma of peritoneum). On effusions, reactive and neoplastic mesothelial cells were regularly negative, while metastatic tumor cells stained positively in 60/62 (96.8%) cases. Among spindle cell neoplasms, only 2/9 biphasic synovial sarcomas and 4/4 follicular dendritic cell sarcomas stained positively. Results indicate that CL-4 reacts with the majority of epithelial neoplasms that often metastasize to serous membranes, representing a pancarcinoma marker with extremely high sensitivity and specificity. CL-4 may be considered a primary immunohistochemical reagent to rule out the diagnosis of mesothelioma.

What are the current best immunohistochemical markers for the diagnosis of epithelioid mesothelioma? A review and update

Numerous immunohistochemical markers that can assist in the diagnosis of epithelioid mesotheliomas, some of which have only recently been recognized, are currently available. Because the various types of carcinomas express these markers differently, their selection for inclusion in a diagnostic panel can vary according to the differential diagnosis. This article provides a critical review of all of the information that is presently available on those markers that are believed to have the greatest potential for assisting in distinguishing between epithelioid mesotheliomas and those carcinomas with which they are most likely to be confused. Information is also provided regarding the panels of immunohistochemical markers that are, at present, recommended in these differential diagnoses.

The diagnostic utility of immunohistochemistry in distinguishing between epithelioid mesotheliomas and squamous carcinomas of the lung: a comparative study

As both mesotheliomas and squamous carcinomas can present a wide variety of morphological patterns, they can on occasion be confused. Recently, some groups of investigators have called attention to the difficulties that sometimes exist in distinguishing between these malignancies and the need to define a panel of markers that can assist in reaching the correct diagnosis. The aim of the present study is to compare the value of the various immunohistochemical markers currently available for the diagnosis of mesothelioma and squamous carcinoma of the lung. A total of 30 epithelioid pleural mesotheliomas exhibiting a solid or predominantly solid pattern, and 30 nonkeratinizing squamous carcinomas of the lung were investigated for the expression of the following markers: podoplanin, calretinin, mesothelin, WT1, keratin 5/6, keratin 7, p63, carcinoembryonic antigen (CEA), MOC-31, Ber-EP4, B72.3, BG-8 (Lewis(y)), leu-M1 (CD15), and thyroid transcription factor-1 (TTF-1). All 30 (100%) of the mesotheliomas reacted for calretinin, mesothelin and keratin 7, 93% each for podoplanin, WT1 and keratin 5/6, 13% for Ber-EP4, 7% each for p63, MOC-31 and BG-8, and 0% for B72.3, CEA, leu-M1 and TTF-1. All 30 (100%) of the squamous carcinomas were positive for p63 and keratin 5/6, 97% for MOC-31, 87% for Ber-EP4, 80% for BG-8, 77% for CEA, 57% for keratin 7, 40% for calretinin and B72.3, 30% for leu-M1, 27% for mesothelin, 15% for podoplanin, and 0% for WT 1 and TTF-1. After analyzing the results, it is concluded that from a practical point-of-view, a combination of two positive mesothelioma markers (WT1 and calretinin or mesothelin) with two negative mesothelioma markers (p63 and MOC-31) would allow the differential diagnosis to be established between epithelioid mesotheliomas and squamous carcinomas of the lung in nearly all instances.

Immunophenotype of high-grade prostatic adenocarcinoma and urothelial carcinoma

Morphologic features alone can usually be used to distinguish prostatic adenocarcinoma and urothelial carcinoma of the urinary bladder. Poorly differentiated tumors, however, can occasionally have features of both neoplasms, making determination of site of origin difficult. No study has provided a panel of antibodies to assist in the distinction of these two tumors. For this study, 73 examples of moderately and poorly differentiated prostatic adenocarcinoma and 46 examples of high-grade urothelial carcinoma were obtained from radical resection specimens. Immunohistochemical studies were performed using the following panel of antibodies: cytokeratin (CK) 7, CK 20, 34betaE12, Leu M1, carcinoembryonic antigen (CEA)m, CEAp, p53, Leu 7, prostate-specific acid phosphatase (PSAP), prostate-specific antigen (PSA), and B72.3. Mucicarmine was also performed. Intermediate and high-grade prostatic carcinoma were compared and then high-grade prostatic carcinoma was compared with high-grade urothelial carcinoma. PSA and PSAP each stained 94% of prostatic adenocarcinomas, but no urothelial carcinomas. Leu 7 stained 94% of prostate and 17% of urothelial carcinomas. Over half of the urothelial carcinomas showed positivity for 34betaE12 (65%), as did two cases of prostatic carcinoma (6%). Eighty-three percent of urothelial carcinomas and 12% of prostatic adenocarcinomas stained with CK 7. Forty-one percent of urothelial carcinomas and 12% of prostatic carcinomas were reactive for CEAm, and p53 stained 33% and 3% of urothelial and prostatic adenocarcinomas, respectively. No significant difference was seen in the expression of CEAp, CK 20, B72.3, Leu M1, or mucicarmine between prostate and urothelial carcinoma. We propose a panel of six antibodies to assist in the distinction of high-grade prostatic adenocarcinoma from high grade urothelial carcinoma: PSA, PSAP, 34betaE12, Leu 7, CK 7, and p53. The first three antibodies should be used initially; if results are negative, the remaining antibodies may be employed.

Metastatic adenocarcinoma of unknown primary origin

Adenocarcinomas account for up to 60% of all metastatic neoplasms of unknown primary origin. In general, adenocarcinomas are the most difficult metastatic tumor to accurately identify the primary site. Some metastatic adenocarcinomas have distinctive histological features that allow for their site determination (eg, colonic adenocarcinoma, bronchioloalveolar cell carcinoma), although the majority of metastatic adenocarcinomas have histological features that are not distinctive enough to allow for a specific diagnosis of their origin. For this reason, electron microscopy and immunohistochemistry have been used to help identify the exact type (origin) of metastatic adenocarcinomas. Relatively specific ultrastructural features used to diagnose metastatic adenocarcinomas of unknown primary origin include tubular myelin, intranuclear surfactant apoprotein tubular inclusions, Clara cell granules, uniform short microvilli with filamentous cores and core rootlets, Langerhans cells associated with neoplastic cells, cytoplasmic hyaline globules, lipid droplets, glycogen, and cytoplasmic crystals. Only a few of these ultrastructural features are absolutely specific. Relatively specific immunohistochemical tests used to diagnose metastatic adenocarcinomas of unknown primary origin include prostate-specific antigen, thyroglobulin, estrogen and progesterone receptor proteins, thyroid transcription factor-I, and surfactant apoproteins. Of these, prostate-specific antigen and thyroglobulin are the most specific. The purpose of this article is to discuss the use of electron microscopy and immunohistochemistry in the site-specific diagnosis of metastatic adenocarcinomas of unknown primary origin.

B72.3 immunoreactivity in benign abdominal lymph nodes associated with gastrointestinal disease

PURPOSE

Immunolocalization of the tumor-associated glycoprotein 72 antigen with the monoclonal antibody B72.3 has been used as a "cancer marker" in radioimmunoscintigraphy and radioimmunoguided surgery (RIGS). Radioimmunoscintigraphy and RIGS have been used to detect occult metastatic deposits from colorectal adenocarcinoma. It has been suggested that RIGS is superior to histologic examination in detecting lymph node metastases from colorectal cancer. To determine the specificity of immunodetection of the tumor-associated glycoprotein-72 antigen as a marker for metastatic adenocarcinoma, we studied benign intra-abdominal lymph nodes with B72.3 and an immunohistochemical technique.

METHODS

Formaldehyde-fixed, paraffin-embedded sections of 276 benign abdominal lymph nodes, resected with 35 cases of colonic adenocarcinoma and 33 cases of benign gastrointestinal disorders, were evaluated for B72.3 immunoreactivity using an avidin-biotin complex immunohistochemical technique. Lymph nodes from cases of colonic carcinoma were also studied with cytokeratin immunostaining to help eliminate occult micrometastases.

RESULTS

B72.3 immunoreactivity was seen in the germinal centers of benign lymph nodes associated with 49 percent of the cases of colonic adenocarcinoma and 12 percent of the cases of benign gastrointestinal disease.

CONCLUSIONS

B72.3 immunoreactivity can be seen in benign abdominal lymph nodes associated with gastrointestinal disease. We advise caution in the use of diagnostic techniques that equate B72.3 immunoreactivity with the presence of adenocarcinoma.