CA 72-4 radioimmunoassay for the detection of the TAG-72 carcinoma-associated antigen in serum of patients

Determination of serum CA724 levels using fluorescence immunochromatography

BACKGROUND

Carbohydrate antigen 724 (CA724) is a sensitive and specific indicator for multiple malignant tumors. The aim of this study was to establish a Eu-time resolved fluorescence immunochromatography (Eu-TRFICO) method for quantitative detection of CA724 in serum.

METHODS

Eu-TRFICO strips were optimized and assembled. The sensitivity, specificity and precision were evaluated using CA724 standard dilutions and matrix serum. Meanwhile, the reference interval, comparison, and sensitivity/specificity were performed using clinical negative/positive gastric cancer serum samples.

RESULTS

The standard curve equation was y = 9.869 x - 154.12 (R2 = 0.993), and the sensitivity was 0.42 U/mL. The common interferents in serum could not affect the quantitative results with low cross-reactivities (all no more than 1.09%). All average recoveries of the intra- and interbatch ranged from 102.38 to 106.40%, and all CVs were below 10%. The reference interval of the healthy subjects was < 4.68 U/mL and the reference interval of the subjects with grade I/II gastric cancer was > 9.54 U/mL. Additionally, a high Pearson r (0.9503) and sensitivity/specificity (92.86%/94.20%) were obtained.

CONCLUSION

This study prepared Eu-TRFICO strips with high sensitivity, specificity, precision and satisfactory clinical testing performance, which provides more options for clinical quantitative and convenient testing of CA724.

The importance of CA 72-4 and CA 19-9 dosing in gastric cancer

Serological analysis of tumor markers has emerged as a non-invasive method for monitoring cancer patients, including tumor recurrence and response to treatment. Tumor markers have the potential to aid in both the diagnosis and prognosis of cancer, but their most important role currently lies in the monitoring of tumor progression. Tumor markers can also provide valuable information on treatment effectiveness, with changes in plasma values indicating tumor regression or progression. This research aimed to investigate the correlation between the serum detection values of three tumor markers - CEA, CA 19-9, and CA 72-4 - and their utility in the diagnosis and prognosis of patients with gastric cancer. The study seeks to uncover the relationship between these tumor markers and the evolution of gastric cancer, providing insights into their potential use in clinical practice.

Serum carbohydrate antigen 72-4 concentrations decrease with age in females but not in males in Beijing, China

OBJECTIVE

Carbohydrate antigen 72-4 (CA72-4) is widely used in the diagnosis and monitoring of many cancers. However, there are few studies on the differences of CA72-4 concentrations in terms of age and gender.

METHODS

A total of 10,957 healthy subjects were divided into two groups according to gender and three age groups. The serum CA72-4 were detected. Statistical analysis was performed by SPSS.

RESULTS

The CA72-4 concentration in female group was significantly higher than that in male group. The concentration of CA72-4 gradually decreased with age. Compared with the age >60 group, the CA72-4 concentrations were increased in the age 46-60 group and 16-45 group (P >0.05, respectively). To better observe the age difference, the age 16-45 and 46-60 groups were combined into the age 16-60 group. In comparison to the age >60 group, the CA72-4 concentration of age 16-60 group was significantly increased (P = 0.000). In the age >60 group, there was no difference between genders. Nevertheless, the difference between the sexes in the age 16-60 group was significant (P = 0.023).

CONCLUSIONS

The reference interval of CA72-4 for local healthy population was established. CA72-4 concentrations gradually decreased with the increase of age, and CA72-4 concentration in females aged 16-60 years (0-18.0 U/mL) was higher than in males (0-14.5 U/mL); however, there was no gender difference in the age group above 60 years old (0-14.5 U/mL). Moreover, in male CA72-4 there was no significant difference among all age groups, while the potential mechanism of female changes with age needs further study.

Potential for Artifacts in Monitoring for the Detection of Tumor Associated Antigens (TAG-72 and CEA) in Serum from Patients Undergoing MAb-based Diagnostic and Therapeutic Protocols

The administration of murine monoclonal antibodies (MAbs) induces, in many patients, an immunological response represented by the development of human anti-mouse antibodies (HAMA). HAMA have been previously shown to interfere in some assays for the detection of CEA, as well as other non tumor related analytes. The present study was performed to determine whether the CA 72-4 assay is affected by the presence of HAMA, and to establish conditions capable of overcoming this artifact. Serum samples obtained from 8/9 patients entered into a therapeutic protocol using 131I-labeled MAb B72.3 showed the development of apparently high levels of TAG-72 during the clinical follow-up concurrent with the appearance of elevated titers of HAMA. Heat treatment at 90°C at pH 5.0 sodium acetate, previously reported as a method of abolishing HAMA interference without affecting CEA levels, resulted in a considerable loss of detectable TAG-72. However, treatment of these samples at 90°C in pH 6.5 Bis Tris abolished the artifact due to HAMA and resulted in the reversion of reported TAG-72 levels to those observed prior to any MAb administration.

As the use of murine M Abs, for both diagnostic and therapeutic applications continues to expand, the identification of this artifactual increase in reported antigen levels due to the development of HAMA has become an important factor in the use of tumor markers, e.g. TAG-72 and CEA, in the follow-up of carcinoma patients.

Clinical Significance of Preoperative Serum Levels of CA 125 and TAG-72 in Ovarian Carcinoma

In a prospective study we evaluated in 48 patients with primary ovarian carcinoma the prognostic value of the preoperative circulating serum levels of CA 125 and TAG-72. Serum levels of CA 125 were above the cutoff level of 35 U/ml in 68% of patients, TAG-72 levels were higher than 6 U/ml in 50% of patients, while the simultaneous use of the two markers increased the sensitivity to 75%. Pretreatment CA 125 and TAG-72 levels were significantly lower (p < 0.05, for both) in patients with well differentiated tumors than in those with moderate or poor differentiation. Similarly, both marker levels were significantly higher (p < 0.001) in patients with residual disease after cytoreductive surgery than in those with no residual tumor. In addition, the CA 125 levels were also higher in initial stages (I-II) than in more advanced stages (III-IV) (p < 0.05), whereas TAG-72 levels were higher (p < 0.05) in patients with mucinous or endometrioid tumors than in those with serous carcinomas. The results further indicated that high preoperative serum levels of CA 125 and TAG-72 were associated with a shorter overall survival (p < 0.001 and p < 0.01, respectively). Finally, separate Cox multivariate analysis showed that preoperative CA 125 and TAG-72 serum levels were, after stage, the strongest factors to predict overall survival (p < 0.0001, p < 0.05 and p < 0.005, respectively) in patients with ovarian carcinoma.

In Vitro and in Vivo Regulation of Human Tumor Antigen Expression by Human Recombinant Interferons: A Review

The ongoing development of monoclonal antibody technology may eventually lead to the selective targeting of human carcinoma lesions by MAbs conjugated with a variety of cytotoxic agents (i.e., radionuclides, drugs, etc.). The antigen phenotype of the carcinoma cell will play an important role in the efficacy of the MAbs. Clearly, the human tumor antigens that are expressed on all carcinoma cells, and with a high antigen density, should provide the optimal target for the MAbs. More often than not, however, the human tumor antigens whose expression is highly selective for human tumor cells will also exhibit a certain degree of heterogeneity. Therefore, the ability of interferon to augment the level of expression of human tumor antigens such as TAG-72 and CEA, may play an important role in an adjuvant setting for immunoscintigraphy and/or immunotherapy. More recent observations have demonstrated that interferon treatment can also enhance the amount of TAG-72 and CEA secreted by the tumor cell. The ability of interferon to enhance the shedding of both TAG-72 and CEA could be of particular importance since recent reports suggest that their presence in the sera of patients diagnosed with gastrointestinal adenocarcinoma may be complementary and that the ability to increase either marker may facilitate earlier diagnosis of recurrent disease. It is conceivable that in subsequent years effective approaches to monitoring and/or treating malignacies may include a new combination of biological/immunological therapy.

Comparison of CA 72-4, CA 19-9 and CEA in the diagnosis and monitoring of gastric cancer

In order to assess the utility of the tumor-associated antigen CA 72-4 in the diagnosis and monitoring of gastric cancer, this tumor marker was measured preoperatively in 718 patients. This group comprised 282 patients with malignant disease (115 with gastric cancer and 167 with other malig-nancies not involving the stomach) and 476 patients with benign surgical diseases. The results were compared with those for carcinoembryonic antigen (CEA) and the tumor-associated antigen CA 19-9. CA 72-4 was above the normal limit of 2.5 U/ml in 61% of the patients with gastric cancer, in 35% of the patients with other malignancies, and in 7% of the patients with benign diseases. CEA and CA 19-9 were elevated in 37% of the patients with gastric cancer (>3 ng/mlfor CEA and >37 U/ml for CA 19-9). CA 72-4 levels were above 10 U/ml in 26% of the gastric cancer patients, in 15% of patients with other malignancies, and in 0.4% of the patients with benign diseases. There was a good correlation between CA 72-4 level and tumor stage in gastric cancer. CA 72-4 serum levels were over 2.5 U/ml in 31%, 48%, 68% and 88% of patients with stage I, II, III and IV disease, respectively. CA 72-4 was found to be more sensitive than CEA and CA 19-9 in detecting recurrences of gastric cancer. In the postoperative-care period, carcinoma recurred in 29 patients. Of these 93% had CA 72-4 concentrations above 2.5 U/ml, whereas only 59% and 35% had pathological CEA and CA 19-9 serum levels (p<0.002, p<0.0001). Although neither CA 72-4 nor CEA and CA 19-9 are sensitive enough for screening and diagnosis of early gastric cancer, CA 72-4 is superior to CEA and CA 19-9 in the detection of gastric cancer recurrences.

CA 72-4 Compared with Cea and CA 19-9 as a Marker of Some Gastrointestinal Malignancies

The objective of this study was to compare CA 72-4 with CEA and CA 19-9 in gastrointestinal malignancies. CA 72-4 was assayed by radioimmunoassay and CEA and CA 19-9 with the Abbott IMx analyser. The study included 52 patients with gastrointestinal cancer and 20 controls with benign gastrointestinal diseases. The 52 cases showed marker sensitivities of 39%, 49% and 35% for CA 72-4, CEA and CA 19-9, respectively, and 64% when the markers were combined. Marker expression in serum was highest in colorectal carcinoma followed by gastric and esophageal carcinoma. The sensitivities of the individual markers in colorectal, gastric and esophageal carcinomas, respectively, were: CA 72-4, 56%, 32% and 18%; CEA, 83%, 33% and 18%; CA 19-9, 53%, 25% and 18%. The sensitivity of the three markers in combination was 89%, 50% and 46% in colorectal, gastric and esophageal cancer, respectively. The specificity of CA72-4, CEA and CA 19-9 was 100%, 72% and 86%, respectively. However, CA 72-4 is not a useful a marker for gastrointestinal cancers because of its poor sensitivity. CEA, which had the best overall sensitivity and a reasonable specificity, was the most useful single marker, especially for colorectal cancer. Whereas the single markers were not useful in gastric and esophageal cancer, the combination of the three may be.

Complementation of Expression of Carcinoembryonic Antigen and Tumor Associated Glycoprotein-72 (TAG-72) in Human Colon Adenocarcinomas

Enzyme-labeled monoclonal antibodies (MAbs) were used in an immunohistochemical, dual-staining study of 10 colon adenocarcinomas. MAbs B72.3 and COL-4, reactive with the high molecular weight tumor-associated glycoprotein-72 (TAG-72) antigen and carcinoembryonic antigen (CEA), respectively, were labeled with horseradish peroxidase or alkaline phosphatase. Dual staining using the two MAbs on a single tissue section (formalin-fixed, paraffin-embedded) showed that greater numbers of carcinoma cells could be detected by using the combination of the two MAbs than could be detected by use of either MAb alone. In many tumors, some carcinoma cells reacted with MAb B72.3, some reacted with MAb COL-4, and some cells reacted with both MAbs. Only 1 of 10 carcinomas showed > 75% reactive cells when stained with each MAb individually. In 9 of 10 cases, however, > 75% of cells reacted when the combination of MAbs was used. Cell surface and cytoplasmic patterns of reactivity were observed with both MAbs while some pools of extracellular mucin were composed of both TAG- 72 and CEA. This study supports the rationalefor the use of a combination of anti-TAG-72 and anti-CEA MAbs for in vitro immunologic detection and potential in vivo immunodiagnostic and immunotherapeutic applications for these MAbs in colon adenocarcinoma patients.

Evaluation of a novel ELISA for the tumor-associated antigen CA 72-4 in patients with ovarian cancer

Aim:

Cancer antigen 72–4 (CA 72–4) is an established tumor marker in ovarian cancer. We evaluated a new solid-phase ELISA (DRG TM-CA 72–4 ELISA).

Materials & methods:

Repeated measures of test samples and controls were performed to evaluate reliability and reproducibility. Afterward, we performed analyses on the sera of 150 patients with primarily diagnosed ovarian cancer. Results were compared with those of the Cobas CA 72–4 kit. Results were correlated with clinical patient data.

Results:

Results of the DRG TM-CA 72–4 ELISA were reproducible with acceptable deviations within measures, and the measured CA 72–4 serum concentrations were well in accordance with the references. High concentrations were significantly associated with grading, tumor stage and tumor residuals after surgery.

Cancer antigen 72–4 is a tumor marker for ovarian cancer. It can be measured in blood samples of patients to monitor the disease. We compared an established method of measurement with a newly designed one (DRG TM-CA 72–4 ELISA) and found that the newer one produced reliable results. Therefore, the DRG TM-CA 72–4 ELISA could be an option for the measurement of cancer antigen 72–4 in ovarian cancer patients.

CA72-4 may contribute to real-time reconnaissance of gastric cancer

Objective: Data from prospective studies indicate a positive impact of gastric cancer screening programs on mortality associated with the disease. Unfortunately, endoscopic procedures, widely regarded as uncomfortable, face low patient compliance, thus underscoring the need for reliable biological markers capable of detection of tumor growth in bodily fluids. Furthermore, in light of the emerging patient-friendly, still devoid of histopathological capabilities, capsule endoscopy, gastric fluid may prove valuable for biomarker-assisted cancer diagnosis. We set out to determine whether CA72-4 measurement in gastric fluid may be of benefit for detection of gastric cancer.Design: Open prospective study.Setting: Sample collection was performed at a tertiary referral center for patients with gastroenterological diseases; immunological analysis was performed at the R&D facility of a commercial biotechnology company. Studies were part of an EU-FP6 project (NEMO).Patients: 176 patients referred for endoscopy due to gastrointestinal complaints.Interventions: Gastric juice was aspirated endoscopically according to standard operating procedures, volume and pH were measured immediately and samples stored at -80°C.Outcome measures: Concentration of CA72-4 tumor marker was evaluated by enzyme-linked immunosorbent assay (ELISA).Results: Median CA72-4 levels were about 4-fold higher in cancer patients compared with patients with normal gastric findings, gastric inflammation, intestinal metaplasia or other diseases (p=0.001). Multivariate linear regression analysis revealed that elevated CA72-4 was significantly predicted by gastric carcinoma adjusted for H. pylori status, age, smoking status, PPI dose, and pH of aspirate (R2=0.27, p<0.0001). In this model, diagnosis of gastric carcinoma had by far the greatest influence. At a cut-off level of 100 U/ml, CA72-4 had 75% sensitivity and 89% specificity for detection of gastric cancer.Conclusions: Based on our findings, CA72-4 level assessment in gastric fluid, featuring yet unmatched accuracy of malignant neoplasia detection may prove beneficial for gastric cancer screening.

MUC1 and the MUCs: A Family of Human Mucins with Impact in Cancer Biology

Mucins represent a family of glycoproteins characterized by repeat domains and a dense O-glycosylation. During the last two decades, the gene and peptide structures of various mucins as well as their glycosylation states were partly elucidated. Characteristic tumor-associated alterations of the expression patterns and glycosylation profiles were observed in biochemical, immunochemical, and histological studies and are discussed in the light of efforts to use the most prominent member in this family, MUC1, as a tumor target in anti-tumor strategies. Within this context the present review, focusing on MUC1, describes recent work on the regulation of mucin biosynthesis by cytokines and hormones, the role of mucins in cell adhesion, and their interaction with the immune system. Important aspects of clinical diagnostics based on mucin antigens are discussed, including the application of tumor serum assays and the significance of numerous studies revealing correlations between the expression of peptide cores or mucin-associated carbohydrates and clinicopathological parameters like tumor progression and prognosis.

Apocrine carcinoma, adenopathies, and raised TAG-72 serum tumor marker

BACKGROUND

The detection of tumor-associated glycoprotein-72 in the serum of patients with carcinomas, basically of the colon, has proved to be of great use in the follow-up of these gastrointestinal adenocarcinomas.

RESULTS

We report the case of a male patient presenting adenopathies in the right axilla. The histologic study of an adjacent skin tumor enabled the diagnosis of a cutaneous apocrine carcinoma. Among the studies made, the increase in the serum antibody CA72.4 can be highlighted. The tumor marker was negative after the extirpation of the skin tumor and the axillary adenopathies.

CONCLUSION

To our best knowledge, this is the first case in which a tumor serum marker is associated with a cutaneous apocrine carcinoma, a fact that should be confirmed with further patients. Its use in the monitoring of this infrequent skin neoplasia is also noteworthy.

Estimation of probability of malignancy using a logistic model combining physical examination, ultrasound, serum CA 125, and serum CA 72-4 in postmenopausal women with a pelvic mass: an international multicenter study

BACKGROUND

To assess the differential diagnostic potential of physical examination, ultrasound, the serum CA 125 assay, and serum CA 72-4 assay, and the contribution of each parameter to a logistic model predicting the probability of malignancy in postmenopausal patients presenting with a pelvic mass.

PATIENTS AND METHODS

In a multicenter, prospective study a total of 155 patients were evaluated preoperatively using a standard protocol for pelvic examination, transvaginal (occasionally additional abdominal) ultrasound, and serum CA 72-4 (cutoff level 3 U/ml) and CA 125 (cutoff level 35 U/ml).

RESULTS

Fifty-nine malignant (39%) and 92 benign (61%) pelvic tumors were found in addition to 4 borderline tumors (3%). Forty-three patients appeared to have ovarian carcinoma, FIGO Stage III or IV in 28 cases. Borderline tumors were excluded from the statistical calculations. The diagnostic accuracy of each single parameter, i.e., pelvic examination, ultrasound, and serum CA 125 and CA 72-4 in discriminating between benign and malignant pelvic masses gave highly similar results (81, 76, 78, and 81% respectively). Best sensitivity was found in pelvic examination (92%); best specificity was found in CA 72-4 (93%). Using logistic regression analysis the power of pelvic examination appeared to be the most relevant (adjusted odds ratio 12.1), followed by ultrasound (odds ratio 9.7), serum CA 125 (odds ratio 5.0), and serum CA 72-4 (odds ratio 4.9). Age appeared to be nonpredictive. The logistic model gives a correct prediction in 87% of all cases.

CONCLUSIONS

The addition of serum CA 72-4 to the combination of pelvic examination, ultrasound, and serum CA 125 leads to an improved discrimination between malignant and benign pelvic masses.

Impact of antigenemia on the bioactivity of infused anti-Tac antibody: implications for dose selection in antibody immunotherapies

In patients with malignancies and immune disorders expressing Tac (alpha chain of the interleukin 2 receptor; CD25), physiologic shedding of this receptor may lead to high blood levels of the soluble form (sTac). This system was used to model the interaction of soluble antigen with antibody in therapeutic settings and to develop rational principles to optimize the delivery of antibody to tumor target cells. First, we confirmed that sTac in vivo can block anti-Tac binding sites and diminish antibody binding to Tac+ cells. Second, the bioactivity of antibody in vivo correlated directly with the amount of antibody infused and inversely with the sTac concentration. Third, bindability of antibody declined in the hours and days after anti-Tac infusion in patients. Finally, tumor targeting was achieved even in the presence of excess sTac, demonstrating a partition of antibody between soluble and cell-bound antigen. A role is proposed for the Brambell receptor (FcRB) to delay saturation of human or chimeric antibodies via differential catabolism of antigen-antibody complexes. Principles are developed for predicting activity of administered antibody in the presence of soluble antigen to assist in dose selection in passive, radioimmuno and immunotoxin therapies.

A CDR-grafted (humanized) domain-deleted antitumor antibody

While several murine monoclonal antibodies (MAbs) directed against carcinoma associated antigens have shown excellent tumor targeting properties in clinical trials, the use of radiolabeled MAbs for both diagnostic and therapeutic applications has been hindered by two factors: (a) the induction of host anti-immunoglobulin (Ig) responses and (b) slow plasma clearance of unbound radiolabeled MAb, resulting in bone marrow toxicity for therapeutic application, and long intervals between MAb administration and tumor detection for diagnostic applications. This report describes the development of the first recombinant Ig with properties designed to reduce or eliminate both of the above problems: a complementarity determining region (CDR)-grafted humanized (Hu) MAb with a CH2 domain deletion (delta CH2). The MAb chosen for engineering was CC49, which is directed against a pancarcinoma antigen designated TAG-72 that is expressed on the majority of colorectal, gastric, breast, ovarian, prostate, pancreatic and lung carcinomas. When characterized for antigen binding in solid phase competition radioimmunoassays, the HuCC49 delta CH2 MAb completely inhibited the binding of murine (mu) CC49 and HuCC49 for TAG-72. The relative affinity constants (Ka) of MAbs HuCC49 delta CH2, HuCC49 and muCC49 were 5.1 x 10(-9), 2.1 x 10(-9) and 2.3 x 10(-9), respectively. The plasma clearance of 131I-HuCC49 delta CH2 was significantly faster than that of intact 125I-HuCC49 after either i.v. or i.p. administration in athymic mice (p(2)0.05). Biodistribution studies in athymic mice bearing human colon carcinoma xenografts after i.v. or i.p. administration of 131I-HuCC49 delta CH2 and 125I-HuCC49 demonstrated the efficient tumor localization and substantially lower percent of the injected dose (%ID/g) of the HuCC49 delta CH2 in normal tissues. This is reflected in the significantly higher radiolocalization indices (%ID/g in tumor divided by %ID/g in normal tissue) observed with the HuCC49 delta CH2 for most normal tissues tested (p(2)0.05). The differential between the rate of plasma clearance of HuCC49 delta CH2 and HuCC49 was even more pronounced in SCID mice, which have been shown to be an appropriate model to study the metabolism of human IgG. These studies thus describe the development of a recombinant Ig molecule which, for the first time, combines 1) the properties of more rapid blood clearance than an intact humanized Ig molecule--without loss of antigen binding affinity--and 2) reduced potential for eliciting a human anti-murine antibody (HAMA) response in patients. These studies also demonstrate the potential utility of HuCC49 delta CH2 for i.p. as well as i.v. radioimmunodiagnosis and radioimmunotherapy in patients with TAG-72 positive tumors.

The intraoperative detection of ovarian adenocarcinoma using radiolabeled CC49 monoclonal antibody and a hand-held gamma-detecting probe

A phase II study to evaluate the safety and efficacy of the 125I-radiolabeled anti-TAG-72 monoclonal antibody, CC49, as a component of a system for the intraoperative detection of occult ovarian cancer deposits was carried out at the University of Nebraska Medical Center. Patients entered into the study were to have surgery for evaluation of their disease status. The primary objective of this study was to determine the ability of a gamma-detecting probe (GDP), the Neoprobe 1000, to intraopertively localize sites of disease not identified by traditional surgical or radiographic evaluation. It was postulated that improved detection of cancer foci might allow for therapeutic excision or might result in an alteration of subsequent treatment. Ten patients were enrolled in the study between May 1993 and March 1994. Nine of the patients were undergoing second-look surgery after completing primary chemotherapy. The remaining patient was having surgery to assess possible cancer recurrence. All patients received an intravenous injection of 2 mCi/1 mg 125I-radiolabeled CC49 without complication. After a mean of 24.5 days, the patients' background radiation counts were deemed low enough for accurate intraoperative cancer localization, and surgery was performed. Any visibly or palpably abnormal areas were biopsied after being evaluated with the GDP. Any areas suspicious for malignancy by GDP evaluation were also biopsied. Two patients without evident disease by radiographic or surgical examination had histologically confirmed metastases localized by the GDP. Four patients had obvious disease at surgery which was variably confirmed by the GDP; two of these patients had baseline elevations in circulating TAG-72 antigen levels that may have affected binding of antibody to the tumor. This system of radioimmunoguided surgery was well tolerated and practical in its application, and it permitted disease detection that resulted in potentially beneficial changes in patient management.

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.

Clinical significance of the tumour markers CA 125 II and CA 72-4 in ovarian carcinoma

In a retrospective study we compared the usefulness of the tumour marker CA 72-4 with the established marker CA 125 II (both EIA on Cobas-Core, Hoffmann LaRoche, Basel Switzerland) at the time of primary diagnosis of ovarian carcinoma (n = 123) in order to discriminate between ovarian carcinomas of different histological type. We compared their diagnostic value, behaviour in follow-up care and evaluated possible combinations. Fixing specificity at 95% vs. benign gynaecological diseases (n = 37) as the clinically relevant reference group, we found cut-off values of 160 U/mL for CA 125 II and 3.0 U/mL for CA 72-4. On the basis of this specificity, we found comparable sensitivity for CA 125 II and CA 72-4 for all kinds of ovarian carcinoma at the time of primary diagnosis. With regard to histology, we found best sensitivity for CA 125 II in serous ovarian cancer and for CA 72-4 in mucinous ovarian cancer. Additional sensitivities were found in ovarian carcinoma in general but little in serous ones. No additive sensitivity was found in mucinous ovarian carcinomas with CA 72-4 as leading marker. In follow-up care, CA 72-4 was the leading marker in II cases and CA 125 II in 16, while in one case both markers were negative. In 6 cases the change of values reflecting clinical follow-up-care was within the so-called reference range. According to our results, at the time of primary diagnosis because of lack of histological findings the combined determination of CA 125 II and CA 72-4 can be recommended. In follow-up care and control of efficacy of therapy the preoperative positive or leading marker is generally sufficient. The determination of both markers in follow-up care is indicated only if they both are negative at primary diagnosis and until one of them becomes clearly positive.

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.

Identification of novel genes from stomach cancer cell lines by differential display

Gastric cancer is a leading cause of cancer death in many parts of the world. None of the tumor markers available to date provide for a reliable screening/diagnostic test. By using differential display technology on gastric cancer nonmetastatic (RF1) and metastatic (RF48) cell lines, we have isolated six novel cDNA clones. Five of them have not been previously identified. However, one of them appears to be the human homolog of the bovine oligomycin sensitivity conferral protein (oscp). Northern blot analysis showed that this clone is expressed at a much higher level in the metastatic (RF48) than the nonmetastatic (RF1) cancer cell line from the same patient. High level expression of the same gene is also observed in the breast cancer cell lines BT20 and T47D. The other five novel clones isolated showed either low or no expression in the RF1 and RF48 gastric cell lines, but variable levels of expression were detectable in breast cancers cell lines and normal tissues.

Interferon alpha enhances expression of TAG-72 and carcinoembryonic antigen in patients with primary colorectal cancer

Interferons up-regulate the expression of human tumor-associated antigens in animal models and in vitro. The use of interferons may enhance the immunodetection and immunotherapy of tumors by monoclonal antibodies that detect tumor antigens. For this strategy to be effective, however, the interferon must have an effect at the site of the tumor. In this study, the induction by interferon alpha (IFN alpha) of two tumor surface antigens was evaluated in six patients with primary colorectal cancer. Patients were treated with IFN alpha and 48 h later underwent resection of the tumor. The interferon treatment induced expression of a tumor-associated glycoprotein (TAG-72) in two patients without antigen expression prior to interferon but had no effect on one TAG-72-negative tumor. IFN alpha did not induce expression of carcinoembryonic antigen (CEA) in the two patients whose tumors were CEA-negative prior to interferon. In all patients with heterogeneous expression of CEA and TAG-72 prior to IFN alpha treatment, preoperative interferon increased the percentage of cells positive for CEA in two patients and TAG-72 in one patient. This study supports the addition of interferon induction to immunotherapy regimens directed at the CEA and TAG-72 cell-surface antigens.

Concentration and distribution of tumor associated antigens TAG-72 and CEA in stomach cancer

We measured the concentration and distribution of tumor associated antigens, TAG-72 and CEA, in stomach cancer by in vitro quantitative autoradiography (IV-QAR). Frozen sections of 33 specimens were incubated with varying concentrations of 125I-labeled CEA-79.1 and B72.3 antibodies specific for carcinoembryonic antigen (CEA) and tumor-associated glycoprotein-72 (TAG-72), respectively. Computer analysis of specific antibody binding gave maximal binding values which were equal to the concentrations of the antigen or epitope. TAG-72 was detected in 25 specimens, at a concentration ranging from 8.4 to 562.9 pmol/g. CEA was detected in 32 of the 33 specimens and its concentration ranged from 8.8 to 525.3 pmol/g. The distribution of TAG-72 by IV-QAR coincided with that of the tumor cells in 41.4% of the pathologic lesions. The distribution of CEA coincided with the tumor cells in 80.5% of pathologic lesions, nearly twice the TAG-72. The concentration of TAG-72 was significantly higher in mucinous adenocarcinoma and mucin containing adenocarcinomas than other types of adenocarcinomas. There was no significant difference in the concentration of CEA among the pathologic types of stomach cancer. In summary, stomach cancer exhibited wide variations in TAG-72 and CEA expression. CEA expression was more frequent and homogeneous than TAG-72.

CA 72-4 serum marker--a new tool in the management of carcinoma patients

Among the new tumor markers that have been recently proposed, CA 72-4 is of particular interest, not only for its capabilities in diagnosing and monitoring certain neoplastic diseases, but also for its excellent specificity. Several studies focused on the potential clinical usefulness of CA 72-4 in gastrointestinal (GI) and gynecological cancer, showing a sensitivity of approximately 40% in colorectal and gastric cancer and 50% in ovarian cancer, with an overall specificity of more than 95%. Longitudinal evaluations of patients with either GI or gynecological malignant diseases demonstrated that significant elevations of CA 72-4 serum levels may be predictive of recurrent disease. Moreover, the combination of CA 72-4 with other known serum markers, such as CEA and CA 19-9 for GI cancer or CA 125 for ovarian cancer, indicated that an increase in the sensitivity can be achieved without substantial changes in the overall specificity, improving the possibility of monitoring these patients. In conclusion, these results provide a strong argument for the use of CA 72-4 in the management of these neoplastic diseases.

Evaluation of tumor-associated glycoprotein-72 and CA 125 serum markers in patients with gynecologic diseases

OBJECTIVE

This study was performed to evaluate the clinical values of tumor-associated glycoprotein-72 serum levels alone or in combination with CA 125 in the diagnosis and monitoring of patients with ovarian cancer.

STUDY DESIGN

Serum samples from 293 patients, 142 with primary carcinoma and 151 with benign diseases of the genital tract, were evaluated for the presence of CA 125, tumor-associated glycoprotein-72, and carcinoembryonic antigen. All patients underwent surgery for the primary tumor, and stage was defined according to the classification of International Federation of Gynecology and Obstetrics.

RESULTS

When the measurement of serum tumor-associated glycoprotein-72 is combined with that of CA 125, the sensitivity for the detection of primary ovarian cancer increased from 60% to 73%, with no significant change in specificity, and resulted in a more accurate clinical assessment for detection of residual disease before the second-look procedure. In fact, when both markers were positive, 100% specificity was achieved; conversely, when both markers were negative, no residual disease was found.

CONCLUSION

These findings suggest that tumor-associated glycoprotein-72 may be considered as a supplementary serum marker for CA 125, providing further clinical information for the diagnosis of primary and recurrent ovarian cancer.

Specific interference with the determination of the tumour-associated glycoprotein 72 by human anti-idiotypic antibodies formed after treatment with the anti-tumour-associated glycoprotein 72 antibody B72.3

Recorded concentrations of the tumour-associated glycoprotein 72 (TAG-72) in ovarian cancer patients after repeated infusion of the antibody B72.3 were found to be falsely elevated when measured with an homologous immunometric assay involving the anti-TAG-72 antibody B72.3 (Test 1), or with an heterologous assay involving CC49 capture and B72.3 detector antibodies (Test 2). Test 1 yielded falsely elevated values up to 10(4) kU/l. Test 2 gave slightly false positive elevations up to 10(2) kU/l for only some of the samples with very high false-positive values in Test 1. The interfering serum components bound to Protein G-Sepharose and could be precipitated with perchloric acid or by heating serum samples to 100 degrees C. Addition of non-specific murine immunoglobulins only partly suppressed false-positive values in both tests. Our results suggest that this interference is caused by human anti-B72.3 IgG induced by B72.3 application, which to some extent specifically binds to determinants of the B72.3 antibody. Heat extraction of serum samples effectively eliminated interferences probably caused by anti-idiotypic antibodies, but did not affect real TAG-72.

Clinical value of serum TAG-72 as a tumor marker for pancreatic carcinoma. Comparison with CA 19-9

We evaluated the sensitivity and specificity of the carbohydrate antigen TAG-72 as a tumor marker for pancreatic cancer compared with the serum values of CA 19-9. Forty healthy controls, 58 patients with pancreatic carcinoma, and 45 patients with chronic pancreatitis were studied. In patients with pancreatic cancer, 47/58 (81%) and 26/58 (45%) had raised serum levels of CA 19-9 and TAG-72, respectively; the sensitivity of the tests was not influenced by jaundice. In the chronic pancreatitis patients, both CA 19-9 and TAG-72 were elevated in 2/45 patients (4.4%). Both tests showed a specificity of 95%. Consequently, the sensitivity of TAG-72 was too low compared with CA 19-9. Moreover, serum TAG-72 could not detect small pancreatic cancers. High levels of both tumor markers were found in advanced stages of cancer. No advantage was found using both CA 19-9 and TAG-72 for improving the detection of pancreatic cancer. TAG-72 serum levels > 10 U/mL are closely related to unresectability of the tumor. Only 4/17 (23%) of patients with resectable tumor had high TAG-72 levels. Serum TAG-72 expression seems to be more frequent in poorly-differentiated tumors than in well-differentiated cancers (56 vs 30% positivity rate).

Expression of CA 72-4 (TAG-72) in the fluid contents of pancreatic cysts. A new marker to distinguish malignant pancreatic cystic tumors from benign neoplasms and pseudocysts

OBJECTIVE

The authors evaluated cyst fluid CA 72-4 as a tumor marker in the differential diagnosis of pancreatic cystic lesions.

SUMMARY BACKGROUND DATA

Pancreatic cystic lesions include inflammatory pseudocysts, serious cystadenomas, and mucinous tumors. Mucinous tumors can be further subdivided into mucinous cystadenocarcinomas and premalignant mucinous cystic neoplasms. The clinical and radiologic features of these lesions are unreliable to make a preoperative diagnosis of these diagnostically difficult lesions. Analysis of aspirated cyst fluid was proposed as an aid to making the preoperative differential diagnosis. Currently, a number of parameters have been reported as useful markers in cyst fluid aspirates, including the tumor markers carcinoembryonic antigen and CA 15.3, enzymes (amylase, lipase, and amylase isoenzymes), relative viscosity, and cytologic analysis. However, owing to the rarity of pancreatic cystic tumors, experience with cyst fluid analysis is limited. To define additional markers that might be useful in the differential diagnosis of pancreatic cysts, the authors measured the tumor-associated glycoprotein 72 (TAG-72) in aspirates from 19 pancreatic cystic lesions.

METHODS

Cyst fluid from 19 pancreatic cysts was obtained by needle aspiration. The tumor marker TAG-72 was measured by a commercial (CA 72-4) immunoassay.

RESULTS

Cyst fluid CA 72-4 levels in mucinous cystadenocarcinomas were markedly elevated (mean, 10,027 U/mL; range, 780 to 34,853 U/mL) compared with that in pseudocysts (mean, 3.8 U/mL; range, < 3 to 5.7 U/mL) and serous cystadenomas (mean and range, < 3 U/mL; p < 0.001). The level of CA 72-4 in benign mucinous cystic neoplasms was intermediate (mean, 44.2 U/mL; range, < 3 to 137 U/mL), but it was statistically different from either carcinomas (p = 0.009) or benign cysts (p < 0.001).

Biologic evaluation of tumor-associated glycoprotein-72 and carcinoembryonic antigen expression in colorectal cancer, Part I

Tumor-associated glycoprotein-72 has been recently suggested as a new serum marker for colorectal cancer. In fact, approximately 40 percent of colorectal cancer patients have positive tumor-associated glycoprotein-72 serum levels at the time of diagnosis, while only 3 percent of patients with benign diseases are positive. A longitudinal evaluation of colorectal cancer patients suggested the utility of combining the measurement of tumor-associated glycoprotein-72 with that of carcinoembryonic antigen to monitor disease status not only at the time of diagnosis, but also at the time of recurrence. Several reports have indicated that the expression of some tumor antigens in colorectal adenomas may correlate with those parameters conventionally considered as indicative of malignant transformation. The presence of tumor-associated glycoprotein-72 in colorectal adenomas has been recently correlated with preneoplastic lesions, suggesting that tumor-associated glycoprotein-72 may be considered as an early marker of neoplastic transformation. The evaluation of tumor antigens can be considered a new tool in the management of colorectal cancer.

Improved experimental radioimmunotherapy of colon xenografts by combining 131I-CC49 and interferon-gamma

PURPOSE

This study was designed to determine whether the ability of interferon-gamma to upregulate the expression of a human tumor antigen improved the therapeutic efficacy of a radionuclide-conjugated monoclonal antibody.

METHODS

Tumor xenografts of the moderately differentiated human colon tumor cell line HT-29 were grown in athymic mice. Constitutive levels of the human tumor antigen, tumor-associated glycoprotein-72, were measured before and after treatment with interferon-gamma. Antitumor effects of an 131I-labeled antitumor-associated glycoprotein-72 monoclonal antibody, CC49, were determined by measuring changes in tumor volumes in the respective groups of athymic mice.

RESULTS

Interferon-gamma induced a time-dependent and dose-dependent increase in tumor-associated glycoprotein-72 expression in the HT-29 tumors. Immunohistochemical staining revealed a more homogeneous tumor-associated glycoprotein-72-positive tumor cell population in tumors isolated from mice treated for eight days with interferon-gamma, which accounted for the enhanced tumor localization of 131I-CC49 in mice. That experimental model was used to examine the antitumor effects of combining interferon-gamma with 131I-CC49. Administration of 300 microCi of 131I-CC49 to mice bearing HT-29 tumors induced a transient suppression of tumor growth. Conversely, a long-term, sustained HT-29 tumor growth suppression was achieved in mice given 300 microCi of 131I-CC49 and interferon-gamma. In fact, the cytokine/radioimmunoconjugate combination eradicated any evidence of tumor in approximately 30 percent of the mice.

CONCLUSION

The ability of interferon-gamma to enhance tumor-associated glycoprotein-72 expression substantially augmented the antitumor effects of the radioimmunoconjugate. Those observations provide additional argument for use of a radioimmunoconjugate in combination with a cytokine to improve tumor diagnosis and therapy.

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

BACKGROUND

The monoclonal antibody B72.3 has been shown to react with several common types of adenocarcinoma. However, the distribution of B72.3 reactivity in adenocarcinomas has not been well-enough defined to determine whether B72.3 immunostaining would be helpful in the diagnosis of adenocarcinoma of unknown origin.

METHODS

Formaldehyde fixed, paraffin-embedded tissue from 476 adenocarcinomas from a variety of primary sites were studied using B72.3 and an avidin-biotin complex immunohistochemical technique.

RESULTS

B72.3 immunoreactivity was seen in 75-100% of the adenocarcinomas from the ovary, endocervix, endometrium, distal esophagus/stomach, colon, lung, breast, prostate, pancreas, and bile ducts. Positive reactions were unusual in thyroid carcinomas (7%) and renal cell carcinomas (11%). B72.3 reactivity was not seen in the 20 hepatocellular carcinomas or 4 adrenal cortical carcinomas studied.

CONCLUSIONS

B72.3 reacts with a wide variety of adenocarcinomas. Immunostaining with B72.3 may be helpful in excluding hepatocellular carcinoma in certain clinical settings.

TAG-72 (CA 72-4 assay) as a complementary serum tumor antigen to carcinoembryonic antigen in monitoring patients with colorectal cancer

BACKGROUND

Serum carcinoembryonic antigen (CEA) is the most frequently chosen tumor marker in the clinical diagnosis of colorectal carcinoma and in the long-term monitoring of patients after tumor resection. In recent years, monoclonal antibody technology has identified several new markers of neoplasia, two of which, TAG-72 and CA 19-9, are found in the sera of patients with adenocarcinoma. Serum CEA, TAG-72, and CA 19-9 were evaluated in 300 patients with either malignant (n = 200) or benign (n = 100) colorectal disease.

METHODS

Serum CEA, TAG-72 (CA 72-4), and CA 19-9 antigen levels were determined with a double-determinant radioimmunometric assay kit. Samples and appropriate standards were assayed in duplicate. The cutoff limits used for each assay were indicated by the manufacturer. All of the results of the CA 72-4, CEA, and CA 19-9 serum assays were separated from the clinical information until the study was completed.

RESULTS

Of the 200 patients with colorectal carcinoma, the percentage of patients whose serum samples were positive for CEA, TAG-72, or CA 19-9 was 43%, 43%, and 27%, respectively. The measurement of TAG-72 with CEA for patients with primary or recurrent colorectal carcinoma increased substantially (to 60%) the percentage of positive serum samples when compared with measuring each serum tumor marker alone. Moreover, the apparent advantage gained by measuring the two tumor markers was achieved with little increase in the number of false-positive results.

CONCLUSIONS

The findings support previous observations of complementary expression of TAG-72 and CEA and indicate that a significant advantage could be gained in the detection of primary and, perhaps, recurrent colorectal carcinoma by incorporating the measurement of serum TAG-72 with that of CEA.

Tumor-associated glycoprotein distribution detected by monoclonal antibody B72.3 in salivary neoplasia

The expression of tumor-associated glycoprotein (TAG-72), an oncofetal mucin-like tumor-associated glycoprotein derived from membrane-enriched fractions of metastatic breast carcinoma, has been detected by monoclonal antibody (MoAb) B72.3 in adenocarcinomas of breast, colon, lung, endometrium, pancreas, and ovary. The authors reported the scope of TAG-72 expression detected by MoAb B72.3 in salivary neoplasia. They examined 96 salivary lesions (53 malignant and 37 benign primary tumors, 2 metastatic carcinomas, and 4 other benign lesions) and 17 normal tissues from parotid glands and found: diffuse TAG-72 expression in 29 of 55 (53%) malignant tumors and 6 of 36 (17%) benign tumors and in no normal tissue; focal TAG-72 expression in 10 of 55 (17%) malignant salivary tumors, 10 of 37 (25%) benign salivary tumors (all benign mixed tumors), and 1 of 17 (6%) histologically normal parotid gland ducts. Any expression of TAG-72, whether diffuse or focal, was found to have a 71% sensitivity for detecting salivary malignant tumors, but an unacceptably low specificity for malignant lesions (57%). Alternatively, if only diffuse TAG-72 expression was regarded as indicative of malignancy, the specificity of diffuse TAG-72 expression was 86%, but sensitivity of detection decreased to 53%. The authors studied a subset of benign and malignant mixed tumors (BMT and MMT) and found that 12 of 15 (80%) MMT diffusely and strongly expressed TAG-72, 2 of 15 MMT (13%) expressed TAG-72 focally, and 1 MMT (7%) was nonreactive. By contrast, most BMT did not express TAG-72; only sparse, focal TAG-72 expression was seen in 10 of 27 (37%) BMT. If diffuse TAG-72 expression is considered indicative of malignancy, its sensitivity and specificity for malignant mixed tumors is 80% and 100%, respectively. The authors suggest that diffuse TAG-72 expression may resolve conflicts in determining whether or not a mixed tumor is malignant.

Comparative analysis of CA72-4, CA195 and carcinoembryonic antigen in patients with gastrointestinal malignancies

To establish further the clinical significance of the novel quantitative immunoradiometric assay system CA72-4 in patients with gastric and other digestive tract malignancies, the sera of a total of 208 subjects have been analysed and levels of carcinoembryonic antigen (CEA) and another promising new tumour marker, CA195, have been compared. Twenty patients had gastric (GC), 60 colorectal (CC), and 14 pancreatic carcinomas (CC); 94 patients had benign disorders, and 20 were healthy volunteers. CA72-4 elevations above normal (greater than 4 U/ml) were observed in 6 (30%) GC, 17 (28%) CC, and 8 (57%) PC patients. CA195 appeared more sensitive and was increased (greater than 10 U/ml) in 35% GC, 70% CC, and in 100% PC patients; CEA levels above normal (greater than 5 ng/ml) were noted in 35%, 45%, and 66% of patients respectively. CA72-4 had a rather high specificity and was increased in only 6/94 (6%) patients with benign diseases, whereas CA195 had a false positive rate of 23%, and CEA of 33%. Among 20 healthy donors, none had elevated levels of CA72-4 or CA195, but marginal elevations of CEA were noted in 3 smokers. Despite some advantage of the new tumour marker CA72-4 in terms of specificity, its value as a serodiagnostic test in gastrointestinal cancer patients seems inferior to that of CA195 and CEA.

Frequent anti-V-region immune response to mouse B72.3 monoclonal antibody

The immune response of 56 colorectal cancer patients to a single infusion of 1 mg of radiolabeled (111In) mouse B72.3-GYK-DTPA immunoconjugate was examined using a double-antigen radiometric assay system. The incidence of antibody response was 48% to polyclonal mouse IgG, 71% to mouse B72.3, and 62% to chimeric B72.3. Twelve patients (23%) had an antibody response to B72.3 V region in the absence of binding to polyclonal mouse IgG. An antiidiotype response was demonstrated in sera from 36% of 25 patients examined and correlated well with chimeric B72.3-GYK-DTPA immunoconjugate binding (r = 0.72, moderately well with mouse B72.3 binding (r = 0.56), and not at all with polyclonal mouse IgG binding (r = 0.28). The peak antibody response occurred most frequently 2 weeks postinfusion, although a "delayed" peak response to chimeric B72.2 occurred in 29% of patients. This study suggests that mouse B72.3 causes an immune response in the majority of patients and that antibody response to the V region is common. Understanding the physiological significance of these antibody responses will require correlation with the kinetics and tumor localization of repeat infusions of such immunoconjugates.

Low frequency and low level of elevation of serum CA 72-4 in human carcinomas in comparison with established tumor markers

We evaluated a new circulating tumor marker, CA 72-4, by comparing its frequency of appearance and level of elevation with other established tumor markers in serial serum specimens from patients with various carcinomas. We found that CA 72-4, though highly expressed and widely found in various tumor tissues, is present at low concentration and frequency in the serum. In breast, colon, ovarian, and pancreatic carcinomas, only 21%, 30.9%, 16%, and 26.5% of specimens, respectively, showed elevated CA 72-4. When elevated, the level of elevation was also low, much lower than that of the dominant markers. Poor response of CA 72-4 to therapy was especially noticeable in serial specimens. In most cases, the CA 72-4 remained normal for the entire series while other markers remained at elevated levels. However, changes of the level of CA 72-4 usually paralleled those of other markers but at a much lower concentration. Simultaneous measurement of CA 72-4 and CA 19-9 appears useful to differentiate colorectal from pancreatic carcinomas when they all contained elevated levels of CA 19-9. There was a much higher ratio of CA 72-4 to CA 19-9 with colon than with pancreatic and other carcinomas (247 +/- 524 vs. 4.7 +/- 6.8).

Monoclonal antibodies in the management of carcinoma patients

The use of monoclonal antibodies (MAbs) in the clinical management of carcinoma patients is reported in the present review. Among the various MAbs generated, MAb B72.3 (LTIB, National Cancer Institute, U.S.A.) has been extensively used in clinical trials either for antigen identification (TAG-72) in sera, or for tumor localization in carcinoma patients. Serum assay results, in colorectal cancer patients, showed the usefulness of the MAb B72.3 in monitoring the clinical course of the malignant disease. Its specific tumor localization (70% of the biopsy specimens) and the immunoscintigraphy studies, after in vivo administration, have also been discussed. The positive results obtained, markedly contributed in the development of a new intraoperative methodology termed "radioimmunoguided surgery".

Tumor-associated glycoprotein-72 serum levels complement carcinoembryonic antigen levels in monitoring patients with gastrointestinal carcinoma. A longitudinal study

Eighty-two patients diagnosed with gastrointestinal (GI) adenocarcinoma were evaluated before and for 26 months after primary tumor resection for the presence of two serum tumor markers: tumor-associated glycoprotein-72 (TAG-72) and carcinoembryonic antigen (CEA). Elevated TAG-72 and CEA serum levels were found preoperatively in 32 (39%) and 34 (41.5%) of the 82 patients, respectively. The percentage of patients with elevated serum levels of either TAG-72 or CEA was 56.1% (46 of 82). Twelve (15%) patients who had normal CEA serum levels had elevated TAG-72 serum levels, and conversely, serum from 14 (17%) patients who were TAG-72 negative were CEA positive. Forty-five of the 82 patients were diagnosed with advanced disease (i.e., Stages C and D for colorectal, Stages III and IV for stomach), and 29 (64.4%) and 26 (57.8%) of those patients had elevated serum levels of TAG-72 or CEA, respectively. Elevated levels of either TAG-72 or CEA, however, were found in sera of 82.2% of patients with advanced GI cancer, which is an increase of 24.4% over the use of CEA antigen alone as a marker of disease. The measurement of both TAG-72 and CEA may improve the diagnosis of patients with GI malignant disease due to the apparent complementary association which exists between these tumor markers. Serum TAG-72 and CEA levels were monitored in 31 patients for varying lengths of time after resection of the carcinoma; 11 patients developed recurrent disease. Sera from nine of 11 (81.8%) of these patients had elevated TAG-72 levels and six of 11 (54.5%) had elevated CEA levels. Tumor marker elevations were observed either before (35 to 166 days) or at the time of diagnosis of recurrence. The elevation of one or both markers correlated with the clinical status in ten of 11 (90.9%) patients with recurrence. In addition, 20 patients who were clinically free of disease after more than 700 days' follow-up had normal serum levels of both TAG-72 and CEA. These findings suggest that the combined use of serum TAG-72 and CEA measurements may improve detection of recurrence in patients with GI cancer and may be useful in the postsurgical management of GI adenocarcinoma patients.

Coordinate elevation of serum markers in ovarian cancer but not in benign disease

Effective screening for occult ovarian cancer will require a strategy that is both sensitive and specific. Preliminary data suggest that CA 125 is elevated at diagnosis in a majority of patients with ovarian cancer. Although CA 125 is sufficiently specific to prompt its evaluation as one component of a strategy to detect ovarian cancer in postmenopausal women, a further improvement in specificity would facilitate cost-effective screening. In an attempt to develop a more specific screening strategy, multiple markers were assayed in a panel of sera from 47 patients with ovarian cancer and in a separate panel of sera from 50 individuals with benign disease whose serum CA 125 levels exceeded 35 U/ml. Among the patients with ovarian cancer, elevations of CA 125 (greater than 35 U/ml) were observed in 91%, CA 15-3 (greater than 30 U/ml) in 57%, TAG 72 (greater than 10 U/ml) in 49%, placental alkaline phosphatase (PLAP) in 25%, human milk fat globule protein (HMFG) 1 in 77%, HMFG2 in 62%, and NB/70K in 57%. Among the 50 sera selected from patients with benign disease, CA 125 was more than 35 U/ml in 100% and more than 65 U/ml in 42%. Among those patients with benign disease and elevated CA 125, NB/70K was elevated in 62%, HMFG1 in 26%, and HMFG2 in 12%, whereas TAG 72 and CA 15-3 were elevated in only 6% and 2%, respectively. In addition PLAP appeared promising; elevated enzyme levels were not found in the benign disease group. Among patients with ovarian cancer with CA 125 levels more than 35 U/ml, either TAG 72 or CA 15-3 was elevated in 77%. In the false-positive group, only 6% had elevations of one or the other marker. The CA 125 levels in cancer patients were, however, substantially greater than in patients with benign disease. If sera from patients with ovarian cancer were diluted to a range comparable to that found in benign disease, at least one of the two confirmatory tests was elevated in 63% of the samples from the malignant cases. Consequently, use of CA 15-3 and TAG 72 in combination with CA 125 can increase the apparent specificity of the CA 125 assay for distinguishing malignant from benign disease. Prospective studies will be required to test critically whether the use of additional serum markers in combination with the CA 125 assay would contribute to the specificity of a cost-effective screening strategy for ovarian cancer.

In vivo and in vitro clinical applications of monoclonal antibodies against TAG-72

Monoclonal antibodies against a tumor-associated antigen (TAG-72) with mucin-like properties have been generated. MAb B72.3 was used to identify and help characterize this antigen. B72.3 has been successfully used for the localization of tumor metastases in situ after i.v. administration. MAb B72.3 has also been used in conjunction with CC49, another anti-TAG-72 MAb, to measure TAG-72 levels in sera and effusions. TAG-72 can be found in the fluids of patients with adenocarcinomas from many different sites. This CA 72-4 double determinant radioimmunoassay in conjunction with assays for carcinoembryonic antigen can identify patients with malignancies with greater sensitivity than either assay alone.

Potential artifact for the increase of tumor associated antigens in serum samples from patients injected with monoclonal antibodies

The administration of [131I]B72.3 MAb for both diagnostic and therapeutic purposes is followed by the development of human anti-mouse antibodies (HAMA) in approx. 70% of patients receiving i.v. doses of MAb above 1 mg. The presence of HAMA in circulation interferes in the detection of the tumor-associated glycoprotein TAG-72 using the CA 72-4 RIA. We have reported elsewhere (Ferroni et al., 1990) that heat treatment at 90 degrees C, pH 6.5, for 15 min is capable of precipitating and/or inactivating HAMA without causing any significant loss in antigen recovery. Furthermore, the removal of the interfering activity leads to a more correct evaluation of TAG-72 serum levels in HAMA-positive serum samples and to a continued use of TAG-72 in the follow-up of patients undergoing MAb-based clinical protocols.

Applications of monoclonal antibodies and recombinant cytokines for the treatment of human colorectal and other carcinomas

Monoclonal antibodies (MAbs) which recognize a human tumor antigen, termed tumor-associated glycoprotein-72 (TAG-72), have successfully been used to localize primary as well as metastatic colorectal tumor lesions in patients. The localization of the anti-TAG-72 MAbs has also been exploited intraoperatively using a hand-held gamma probe. That procedure, termed radioimmunoguided surgery (RIGS), has identified occult tumors which were not detected using standard external imaging techniques. In another clinical trial, interferon-gamma (IFN-gamma) was administered intraperitoneally to patients diagnosed with either gastrointestinal or ovarian carcinoma with secondary ascites. Analysis of the tumor cells isolated from the malignant ascites revealed a substantial increase in TAG-72 expression on the surface of tumor cells isolated from seven of eight patients. The results provide evidence that the combination of an anti-carcinoma MAb with the administration of a cytokine, such as IFN-gamma, may be an effective approach for the detection and subsequent treatment, of colorectal carcinoma.