Visual evoked potentials in phenylketonuria: association with brain MRI, dietary state, and IQ

Tumor-associated glycoprotein 72 is a high-molecular-weight sialomucin that is expressed selectively in various adenocarcinomas, including those of the prostate. We utilized the monoclonal antibodies B72.3 and CC49 to examine the expression of TAG-72 in high-grade prostatic intraepithelial neoplasia (PIN), localized adenocarcinomas (pathologic stages B and C), as well as matching primary and nodal lesions from patients with stage D adenocarcinomas. Immunoreactivity within PIN lesions was detected within 20 (87%) and 17 (74%) of 23 specimens immunostained with B72.3 and CC49, respectively. Benign epithelium and stromal tissue did not immunostain with either antibody at the concentrations tested. Immunostaining was detected within the malignant cells in 30 (77%) and 35 (90%) of 39 localized adenocarcinomas using B72.3 and CC49, respectively. Immunostaining was localized to the cytoplasm and cellular membranes of the malignant cells and within the lumen of malignant glands. Seven of 17 (41%) primary lesions from patients with stage D adenocarcinomas demonstrated immunoreactivity when stained with B72.3. Immunoreactivity was detected in 8 of 10 (80%) of these tissues immunostained with CC49. Within nodal lesions obtained from these patients, immunostaining was observed in 3 of 17 (18%) and 6 of 10 (60%) of the specimens immunostained with B72.3 and CC49, respectively. We used a semiquantitative technique to compare the extent of immunoreactivity among well-differentiated (Gleason score < 6), moderately differentiated (Gleason 6-7), and poorly differentiated (Gleason score > 7) tumors. We observed an inverse correlation of TAG-72 expression to Gleason scores. Furthermore, TAG-72 expression was reduced in the matching primary and metastatic lesions of stage D adenocarcinomas as compared to localized lesions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Construction of phosphorylatable chimeric monoclonal antibody CC49 with a tyrosine srC kinase recognition site

A phosphorylation site for a tyrosine kinase was introduced into chimeric monoclonal antibody CC49 (MAb-chCC49) by inserting a synthetic fragment (Tyr) encoding one tyrosine kinase phosphorylation site into an expression vector. The phosphorylation site was created by incorporating the predicted consensus sequences for phosphorylation by the tyrosine kinase at the carboxyl terminus of the heavy chain constant region of the MAb-chCC49. The resultant modified MAb-chCC49 (MAb-chCC49Tyr) was expressed and purified. The MAb-chCC49Tyr protein can be phosphorylated by the tyrosine Src kinase with [gamma-32P]ATP to high radiospecific activity. The 32P-labeled MAb-chCC49Tyr protein binds to cells expressing TAG-72 antigens. The introduction of phosphorylation sites into monoclonal antibodies (MAb) provides a new reagent for the diagnosis and treatment of cancer. This demonstrates that, as was described for the cAMP-dependent protein kinase site, a tyrosine phosphorylation site can also be used to introduce phosphorylation sites into proteins.     

Specificities of anti-sialyl-Tn and anti-Tn monoclonal antibodies generated using novel clustered synthetic glycopeptide epitopes

The fine specificities of MAbs generated using novel synthetic clustered STn and Tn glycopeptides as immunogens were compared with the anti-TAG-72 antibodies B72.3 and CC49. Hapten inhibition experiments demonstrated the specificity of several of the MAbs for STn and Tn expressed on ovine submaxillary mucin and tumor derived MUC-1 mucin. Amongst the STn specific MAbs only the B195.3 MAb shows absolute dependence on the presence of sialic acid and specificity to the simple disaccharide NANAA alpha2-6-GalNAc. Identification of tumor associated carbohydrate epitopes in cluster and monomer configurations are possible using MAbs detecting the defined structure specificities described herein.     

Systemic administration of recombinant interferon alfa in carcinoma patients upregulates the expression of the carcinoma-associated antigens tumor-associated glycoprotein-72 and carcinoembryonic antigen

PURPOSE: The ability of interferons (IFNs) to enhance tumor-associated antigen expression may be an important approach to enhance the efficacy of some monoclonal antibody (MAb)-based protocols for tumor diagnosis and/or therapy. The present study was designed to determine whether systemic IFN alpha-2a administration (via the intramuscular [IM] route) could upregulate the expression of tumor-associated glycoprotein-72 (TAG-72) and/or carcinoembryonic antigen (CEA) at histologically confirmed sites of carcinoma. PATIENTS AND METHODS: Eighteen patients diagnosed with gastrointestinal (GI) carcinoma received systemic IFN alpha-2a according to four dose schedules. In cohorts I and II, patients received two injections of 3 or 6 x 10(6) U IFN alpha-2a per injection, respectively. Patients in cohorts III and IV received the same doses of IFN alpha-2a, 3 and 6 x 10(6) U, respectively, but three injections were given. Tumor and normal colonic mucosa biopsies were obtained from each patient by endoscopy before IFN alpha-2a and after IFN alpha-2a at surgery. The levels of TAG-72 and CEA expression were measured by (1) immunohistochemistry and reported as percent antigen-positive tumor cells, as well as the relative staining intensity, and (2) a quantitative radioimmunoassay. RESULTS: TAG-72 and CEA levels were consistently increased in tumor biopsies taken from patients in cohorts III and IV. For example, of 10 patients treated in cohorts III and IV, eight had enhanced TAG-72 expression when measured either as percentage TAG-72-positive tumor cells or as an increased MAb staining intensity following IFN alpha-2a. CEA expression in tumor biopsies from seven of 10 patients in cohorts III and IV was also elevated following IFN alpha-2a treatment. Quantitative analysis of TAG-72 and CEA levels in tumor biopsies confirmed higher tumor antigen levels following IFN alpha-2a administration. No such increases in TAG-72 or CEA levels were observed in tumor samples taken from patients in cohorts I and II. CEA or TAG-72 expression in samples of histologically confirmed normal colonic mucosa showed little or no change after IFN alpha-2a treatment. CONCLUSION: Systemic IFN alpha-2a administration can upregulate TAG-72 and CEA expression at distal tumor sites, which may play an important role in immunodiagnosis and therapy.     

Localization of tumor-reactive lymph node lymphocytes in vivo using radiolabeled monoclonal antibody

BACKGROUND: Lymph node lymphocytes vary in their responsiveness to tumor. A technique has been developed that uses radiolabeled monoclonal antibody (MoAb) against the tumor-associated mucin, TAG-72, and a gamma-detecting probe by which lymph nodes containing microscopic tumor and/or shed TAG-72 can be identified in vivo. The immunologic characteristics of these lymph nodes were examined. METHODS: Patients with colon cancer received 125I-labeled MoAb CC49 by intravenous injection preoperatively. During laparotomy lymph nodes that appeared normal on inspection and palpation but which contained radiolabeled MoAb were identified using a hand-held gamma-detecting probe. These lymph nodes and other lymph node and tumor specimens were resected for analysis. RESULTS: Lymph nodes identified by the probe were found by immunohistochemical studies to contain microscopic tumor and/or shed antigen associated with germinal centers. They were characterized by greater CD4+:CD8+ ratios, rates of expansion, and cytolytic activity compared with lymphocytes from lymph nodes with macroscopic tumor, noninvolved lymph nodes, and tumors. All lymph node lymphocytes identified by the probe demonstrated significant proliferative responses to autologous tumor and, in contrast to lymphocytes from noninvolved lymph nodes, significant proliferative responses to allogeneic TAG-72+ tumor cells and to soluble TAG-72+ mucin. CONCLUSIONS: By locating lymph nodes with microscopic tumor and/or shed antigen, the use of radiolabeled MoAb in vivo can be used to reproducibly identify tumor-reactive lymph node lymphocytes. This technique may be useful in identifying cells for use in adoptive immunotherapy programs and in studying the regulation of immune responses in vivo.     

Oestrogen receptors in canine mammary tumours

One hundred and twenty-nine canine mammary tumours of varying histological types were examined for the presence of oestrogen binding protein by the dextran-coated charcoal method with the binding parameters of the reaction determined by Scatchard plots. By this method, 39 per cent of the 129 mammary tumours were shown to contain oestrogen receptor protein. This figure fell to 25 per cent for benign tumours and rose to 52 per cent for malignant tumours. There was no correlation between the histological nature of tumours and oestrogen receptor content in either benign or malignant forms. Oestrogen receptors were not demonstrable in normal mammary tissues. Whether the presence of oestrogen receptors in a tumour is indicative of hormonal dependence as is reported for human breast tumours is being investigated in the bitch.     

Expression of fibronectin and its integrin receptor alpha 5 beta 1 in canine mammary tumours

Fibronectin and its integrin receptor alpha 5 beta 1 were studied by immunohistochemical methods in five normal canine mammary glands, four dysplastic glands and 18 mammary tumours. The aim of the study was to evaluate the possible changes in the alpha 5 beta 1 integrin receptor and its ligand fibronectin in relation to the metastatic capacity of canine mammary neoplasms. The immunostaining of alpha 5 beta 1 was very uniform in the hyperplastic glands but uneven in the mammary tumours. The expression of alpha 5 and beta 1 was diminished in metastatic tumours but there were some alpha 5-positive cells with pronounced features of malignancy and immaturity. Stromal fibronectin was increased in most cases and cytoplasmic staining of fibronectin was observed in epithelial and myoepithelial cells in mammary neoplasms but not in normal or dysplastic mammary tissue. There was no relationship between the content of alpha 5 beta 1 and the expression of fibronectin in canine mammary tumours.     

The dysregulated podocyte phenotype: a novel concept in the pathogenesis of collapsing idiopathic focal segmental glomerulosclerosis and HIV-associated nephropathy

Immunocytochemical demonstration of metallothionein (MT) has been reported as a useful prognostic tool in human breast cancer. The aim of this study was to determine the immunohistochemical location of MT in canine mammary tumours and its possible correlation with the morphologic characteristics of these tumours. Surgical specimens from spontaneous malignant (n = 20) and benign mammary neoplasms (n = 20) were processed for routine histological examination and immunohistochemical study. An indirect immunoperoxidase technique, using monoclonal antibody E9 against horse MT was employed. Intensity of the stain, the percentage of immunoreactive tumour cells and immunohistochemical overexpression of MT was estimated for each case. Metallothionein over-expression, defined as those cases with more than 10% immunopositive cells, was detected in both benign and malignant mammary tumours. However, strong immunostaining intensity was seen in benign tumours, whereas in malignant tumours immunopositive cells stained weakly. Positive MT immunostaining occurred in neoplastic epithelial cells, and some chondrocytes present in mixed mammary tumours. However, staining intensity was variable in immunopositive cells. Differences in staining intensity between the primary malignant mammary tumour, tumour emboli and metastatic cells within a lymph node were also noted. Myoepithelial cells and connective tissue did not stain for MT. We concluded that metallothionein immunostaining cannot be used as a diagnostic or prognostic tool in canine mammary neoplasms. However, results of this study support the hypothesis that MT has a role in tumour proliferation and tumour progression.     

Characterization of a new breast cancer-associated antigen and its relationship to MUC1 and TAG-72 antigens

We have characterized a new tumor-associated antigen defined by monoclonal antibody (MAb) generated against HMA-1 breast cancer cell line. MAb AM-1 was selected based on its preferential reactivity to breast cancer cells versus to normal or benign epithelial cells by immunofluorescence and immunohistochemical assays of cultured, or fresh specimens. AM-1 demonstrated strong reactivity to breast cancer cell lines including HMA-1, YMB-1-E, YMB-1 and MDA-MB-231 in flow cytometry. In immunoprecipitation, AM-1 recognized high molecular weight components of 160-210 kDa and > 370 kDa. Reactivity with HMA-1 cells was diminished markedly when treated by heat, protease or periodate, suggesting that the antigenic epitope is composed with carbohydrates and peptides. Enzyme digestion of precipitated antigens demonstrated that the antigen contains O-linked and N-linked carbohydrates with neuraminic acid structures. Furthermore, binding inhibition and sandwich ELISA assays using MAbs reactive with known breast cancer-associated antigens and synthetic MUC1 core peptide (PDTRPAPGSTAPPAHGVTSAPDTR) demonstrated that the antigen is distinct from CEA, TAG-72 or MUC1, while the antigen conjoins with MUC1 and TAG-72 as a trimmer form in HMA-1 cells. These results suggest that AM-1 recognizes a novel glycoprotein which is abundant in breast cancer, and may be utilized in the management of breast cancer patients.     

Production of mouse monoclonal anti-idiotypic antibodies specific to epitopes of tumor-associated mucin TAG-12

The tumor-associated mucin-glycoprotein TAG-12 is strongly expressed in approximately 96% of all breast cancer patients and nearly 68% of all ovarian cancers. The experimental results of this work indicated that humoral immune response against TAG-12 is possible. Immunization with anti-idiotypic monoclonal antibodies produces this response. In this experiment, anti-idiotypic monoclonal antibodies represent the internal image of a specific epitope on TAG-12. Monoclonal antibody (MAb) 12H12 was selected to produce anti-idiotypic antibodies (anti-Ids) because of its high reactivity with TAG-12. Syngeneic murine anti-Ids were developed by immunization of BALB/c mice with the 12H12-Fab-KLH conjugate. A competitive assay with purified TAG-12 was utilized to identify anti-Ids with mirror image function. Two MAbs with "internal image" specificity were selected, 5H8 and 5H2. Two New Zealand White rabbits were immunized with 5H8. Serum samples tested 6 weeks after the initial immunization showed comparable titers against TAG-12. The binding capacities of the rabbit sera to different human breast as well as nonbreast cancer cell lines demonstrated strong binding with TAG-12-positive breast cancer cell lines. Competitive inhibition assays demonstrate that Ab3 and purified TAG-12 totally inhibit the binding of 12H12 antibody to TAG-12-positive cells. No inhibition was detectable with unrelated MAbs or normal mouse immunoglobulin. Binding assays with polyclonal Ab3 serum and several human cancer cell lines showed reactivity to nearly every tested cell line. Soluble TAG-12 showed no inhibition, indicating that this binding is due to a different set of idiotypes. Anti-Id 5H8 elicited an immune response to TAG-12. Utilization of anti-Id as a vaccine against the breast cancer-associated tumor antigen TAG-12 was successfully demonstrated in a xenogeneic animal model.     

Physiologic, biochemical and genetic aspects of malignant hyperthermia

The value of the TAG-72 (CA 72-4) serum marker in primary diagnosis was investigated in 110 patients with histologically diagnosed ovarian cancer. A reference group consisted of 103 patients with benign pelvic masses. Compared to the well-established CA-125, TAG-72 showed a low sensitivity of 42% in the detection of ovarian cancer. By contrast, when the cut-off level for TAG-72 was set at 6 U/ml, it showed a very high specificity of 99%. When the measurement of TAG-72 was combined to that of CA-125, improvements in both the specificity (as compared to a single CA-125 determination) and the sensitivity (as compared to a single TAG-72 assay) were observed. In such a combined assay, our results suggest that the best predictive value (positive and negative) was obtained if CA-125 is assigned a relatively high cut-off value (65 U/ml) in conjunction with a low cut-off level (3.2 U/ml or 4 U/ml) for TAG-72. In the present study, at threshold values of 65 U/ml respectively, a sensitivity of 86%, a specificity of 83% and a positive and negative predictive value of 85% were obtained. In mucinous carcinomas of the ovary, however, the additional TAG-72 determination did not lead to a better predictive power than did CA-125 measurement alone.     

Clinical comparison of radiolocalization of two monoclonal antibodies (mAbs) against the TAG-72 antigen

Ten patients with colorectal cancer metastases received 125I-B72.3 and 131I-CC49 prior to laparotomy (five patients received 1 mg, and five 20 mg of each mAb). Tumor:serum ratios of 131I-CC49 were better than those of 125I-B72.3 (P < 0.01 at 1 mg; P = 0.05 at 20 mg; P < 0.01 at both doses). All known lesions > or = 1 cm in diameter were visualized at the 20 mg dose. There was no difference in absolute tumor uptake of 125I-B72.3 or 131I-CC49. We conclude that mAb CC49 has better relative uptake in colorectal cancers than mAb B72.3.     

Identification of novel membrane structures in Plasmodium falciparum infected erythrocytes

Phosphorylation sites were introduced into chimeric monoclonal antibody CC49 (MAb-chCC49) by inserting synthetic fragments encoding two and six phosphorylation sites into an expression vector, pdHL7. The phosphorylation sites were created by using the predicted consensus sequences for phosphorylation by the cAMP-dependent protein kinase to the carboxyl terminus of the heavy chain constant region of the MAb-chCC49. The resultant modified antibodies (MAb-chCC49K1 and MAb-chCC49-6P) were expressed in NS0 cells and purified. The MAb-chCC49K1 protein contains two phosphorylation sites per heavy chain whereas the MAb-chCC49-6P protein contains six sites per heavy chain. Both MAb-chCC49K1 and MAb-chCC49-6P proteins can be phosphorylated by the catalytic subunit of cAMP-dependent protein kinase with [gamma-32P]ATP to high specific activity. The 32P-labeled MAb-chCC49K1 and MAb-chCC49-6P proteins bind to cells expressing TAG-72 antigens. The introduction of phosphorylation sites into a monoclonal antibody provides a reagent for the diagnosis and treatment of cancer. The use of multiple phosphorylation sites provides antibodies with very high specific radioactivity and demonstrates that cassettes of phosphorylation sites can be introduced into proteins without altering their functional activity.     

Agglutination reactions of spontaneous canine tumour cells, induced by concanavalin A, demonstrated by an isotopic assay

Quantitative assessment of the agglutination of 51Cr labelled canine cell suspensions to canine kidney cell monolayers has been performed over a range of concanavalin A concentrations. Agglutination was observed with all cell cultures tested, comprising four spontaneous canine melanomas, two canine mammary carcinomas, a benign mammary tumour and a contact-inhibited kidney cell line. The melanomas tested showed strong specific inhibition of concanavalin A agglutination by 10(-2)M alpha-methyl-D-glucopyranoside. Inhibition of agglutination of mammary tumour and kidney cells was weaker and less specific. Agglutination was inhibited at 4degrees C. Reduced agglutination to glutaraldehyde-fixed mono-layers was observed in the case of mammary tumours but was absent when contact-inhibited kidney cells were tested. The specificity of the reaction for transformed cells and the parameters involved are discussed.     

Phase II study of dual 131I-labeled monoclonal antibody therapy with interferon in patients with metastatic colorectal cancer

The combination of COL-1 (anti-CEA) and CC49 (anti-TAG-72) has shown an increase in binding and distribution in colon cancer by immunoperoxidase staining compared to either antibody alone. To overcome tumor heterogeneity and allow delivery of higher radiation dose, 131I-labeled COL-1 and CC49 at a total dose of 75 mCi/m2 (2775 MBq/m2) were simultaneously administered to 14 patients with metastatic colon cancer. alpha-IFN (3 x 10(6) IU) was given s.c. on days -5 to +3 to increase carcinoembryonic antigen and TAG-72 antigen expression. Most patients had mild symptoms during IFN therapy, including mild neutropenia, fever, and malaise, which rapidly subsided after IFN cessation. No acute allergic reactions occurred with radioimmunotherapy; two patients experienced transient, delayed grade 2 arthralgias. Transient neutropenia and/or thrombocytopenia, which was maximal at 4-6 weeks, were consistent side effects without adverse events. All patients had tumor localization, and 13 of 14 patients achieved 4+ (highest grade) localization readings to at least one known site of disease. No objective responses occurred; 4 patients were stable and 10 progressed. Tumor dose estimates varied from 393 to 1327 cGy, including liver and extrahepatic sites. Combining two complementary antibodies and IFN administration appeared to increase localization intensity and radiation doses at tumor sites as compared to historical controls. The amount of radiation delivered to tumor sites was still below that required to cause tumor regressions in metastatic colorectal cancer.     

Intraoperative detection of occult colon cancer micrometastases using 125 I-radiolabled monoclonal antibody CC49

BACKGROUND: The detection of locally-disseminated disease is one of the principal goals of oncologic surgery. For this study, a hand-held, gamma-detecting probe was used intraoperatively to assess the extent of colorectal carcinoma in patients previously injected with radiolabeled antibody to the TAG-72 antigen (CC49); this technique is known as Radioimmunoguided Surgery (RIGS) (Neoprobe Corporation, Dublin, OH). RIGS-positive areas (i.e. those with increased signal over background) have previously been shown to contain carcinoma in a high proportion of cases. However, some RIGS-positive areas had no tumor detectable by clinical examination or routine histopathologic analysis. This study was undertaken to determine if the presence of occult metastases might account for this disparity. METHODS: A total of 57 regional lymph nodes (LN), resected from 16 patients with primary (9) or recurrent (7) colorectal carcinoma, were studied. The patients were injected with 125I labeled CC49 murine monoclonal antibody approximately 3 weeks prior to surgery. After routine histologic evaluation, the LN were analyzed for occult metastases; paraffin sections were cut at 5 levels (50 micron apart) and were examined by histology (hematoxylin and eosin stain [H & E]) and by immunohistochemistry (IHC) with a cocktail of monoclonal antibodies to cytokeratins. RESULTS: Fifty-seven LN were included in this study; 17 were H & E-positive (i.e., contained tumor by routine histologic examination [overt tumor]), while 40 LN were H & E-negative (i.e., no evidence of tumor after routine histologic examination). Thirty-nine LN were RIGS-positive, but only 14 of these were H & E-positive. Of the 25 RIGS-positive/H & E-negative LN, 10 (40%) demonstrated the presence of occult metastases after serial section/IHC analysis. Thus, a total of 27 LN contained metastatic carcinoma (17 overt, 10 occult); routine histologic analysis was able to identify tumor in only 17 of these 27 LN (63%), while the probe signaled the presence of tumor in 24 of these LN (89%). None of the RIGS-negative/H & E-negative LN were found to have occult metastases (0/15). Specific immunoreactivity with CC49 antibody was observed in 5 of 15 RIGS-positive/H & E-negative LN in which no tumor could be identified by any method (histopathology or IHC. CC49 immunoreactivity was not observed in 15 RIGS-negative/H & E-negative LN. CONCLUSIONS: The finding of a RIGS-positive LN had a significant association with the presence of tumor cells (P < 0.05). In this study, the RIGS procedure was more sensitive than clinical or histopathologic examination in detecting the regional spread of a tumor. Furthermore, in LN that showed no evidence of tumor by routine histopathologic examination, a positive RIGS reading was significantly associated with the presence of occult LN metastases (P < 0.01). This study is the first to demonstrate the detection of histologically occult tumor by a remote imaging device. RIGS assessment is a highly sensitive method for detecting occult tumor deposits, and may guide therapeutic intervention in patients with colorectal carcinoma.     

Allergic eye disease mechanisms

The histologic distinction between epithelial peritoneal mesothelioma and papillary serous carcinoma diffusely involving the peritoneum may be difficult. Although some investigators have indicated that immunohistochemistry can facilitate this differential diagnosis. only a few studies using a limited number of markers have been published. In this study, the immunoreactivity of keratin 5/6, vimentin, epithelial membrane antigen, thrombomodulin, calretinin, MOC-31, Ber-EP4, carcinoembryonic antigen, TAG-72 (B72.3), CD15 (Leu-M1), placental alkaline phosphatase, CA19-9, CA-125, HBME-1, 44-3A6, and S-100 protein was investigated in 35 epithelial peritoneal mesotheliomas, and 45 papillary serous carcinomas [30 ovarian (10 primary and 20 metastatic to the peritoneum) and 15 papillary serous carcinomas of the peritoneum]. After analyzing the results, it is concluded that calretinin, thrombomodulin, and keratin 5/6 are the best positive markers for differentiating epithelial malignant mesotheliomas from papillary serous carcinomas diffusely involving the peritoneum. The best diagnostic discriminators among the antibodies considered to be negative markers for mesothelioma are MOC-31, B72.3, Ber-EP4, CA19-9, and Leu-M1. Immunostaining for carcinoembryonic antigen, placental alkaline phosphatase, epithelial membrane antigen, vimentin, HBME-1, 44-3A6, CA-125, or S-100 have little or no diagnostic utility in establishing the differential diagnosis between these conditions. The results of this study also confirm previous observations indicating that both papillary serous carcinomas of the peritoneum and serous carcinomas of the ovary have a similar phenotype and, therefore, immunohistochemical studies are not useful in separating these entities.     

Interferon-gamma and monoclonal antibody 131I-labeled CC49: outcomes in patients with androgen-independent prostate cancer

To assess the tumor targeting, safety, and efficacy of monoclonal antibody 131I-labeled CC49 in patients with androgen-independent prostate cancer, 16 patients received 75 mCi/m2 of the radiolabeled antibody after 7 days of IFN-gamma pretreatment. Sequential tumor biopsies in three patients showed a median 5-fold (range, 2-6-fold) increase in the proportion of cells staining positively for the TAG-72 antigen, whereas one showed a decrease in staining. Fourteen patients received 131I-labeled CC49, whereas 2 showed a disease-related decrease in performance status, precluding antibody treatment. The antibody localized to sites of metastatic androgen-independent prostate cancer in 86% (12 of 14; 95% confidence interval, 57-95%) of cases. Both osseous and extraosseous sites were visualized, and in six (42%) patients, more areas were visible when the radioimmunoconjugate was used than were apparent when conventional scanning techniques were used. The localization of the conjugate in the marrow cavity was usually a site not visualized by the radionuclide bone scan, in which the isotope localizes primarily to the tumor-bone interface. The dose-limiting toxicity was thrombocytopenia because five (36%) patients showed grade IV and seven (50%) showed grade III effects. In addition, six (42%) patients, four of whom were hospitalized, showed a flare in baseline pain, and four showed a decrease in pain. No patient showed a >50% decline in prostate-specific antigen, although radionuclide bone scans remained stable in four cases for a median of 4 months. The results are consistent with dosimetry estimates showing that the delivered dose to tumor was subtherapeutic and suggest that approaches that exclusively target the bone tumor interface or the marrow stroma may be unable to completely eradicate disease in the marrow cavity. For CC49, improving outcomes would require repetitive dosing, which was precluded by the rapid development of a human antimouse antibody response.     

T cell targeting of TAG72+ tumor cells by a chimeric receptor with antibody-like specificity for a carbohydrate epitope

BACKGROUND & AIMS: Chimeric receptors with specificity for defined tumor antigens are valuable tools for targeting cytolytic T cells specifically to tumor cells. The aim of this study, for the situation of gastrointestinal cancer, was to investigate the generation of a chimeric T cell receptor that specifically binds the tumor antigen TAG72 (CA72-4) and transmits a signal for cellular activation. METHODS: A single-chain antibody (scFv) was derived from the monoclonal anti-TAG72 antibody B72.3 by phage display techniques (B72.3-scFv) and fused to the signaling unit of the Fc epsilon-RI receptor gamma chain, resulting in a chimeric signaling receptor, B72.3-scFv-gamma. RESULTS: The B72.3-scFv and the chimeric B72.3-scFv-gamma receptor bound specifically to the TAG72 antigen. After transfection, T cells expressing the chimeric B72.3-scFv-gamma specifically recognized TAG72 positive cells. Cross-linking of the chimeric receptor with antigen resulted in interleukin 2 release and cytolytic activity against TAG72 positive tumor cells in vitro. CONCLUSIONS: T cells equipped with the chimeric anti-TAG72 receptor can be specifically activated to target and lyse TAG72 positive gastrointestinal tumor cells.