Circulating tumor-associated antigen detected by the monoclonal antibody HMFG2 in human epithelial ovarian cancer

The Monoclonal Antibody-defined CAR-3 Antigen is a Serological Marker Associated with Pancreatic Carcinoma

The monoclonal antibody-defined CARS antigen is a new carcinoma associated marker which is expressed on a mucin-like molecule. Serum concentrations of CARS were assayed in 181 patients with carcinomas of different organs, 20 patients with non-carcinomatous malignancies, 123 patients with inflammatory diseases and 150 healthy controls. Serum levels of CARS were significantly increased in 51% of the patients with pancreatic carcinomas, in 60% of patients with biliary tract carcinomas and in about 15% of the patients with carcinomas of the digestive apparatus. Sera from patients with breast carcinomas were negative, as well as sera from patients with melanomas or sarcomas. CAR-3 values in samples from patients with chronic pancreatitis were constantly negative, as were samples from healthy donors. Significant concentrations of CAR-3 were detected in 20% of the sera from patients with acute pancreatitis and in 15% of the sera from patients with cirrhosis. Because of its high specificity for pancreatic carcinomas compared to chronic pancreatitis, CARS seems a promising marker for distinguishing between neoplastic and chronic inflammatory diseases of the pancreas, whose differential diagnosis is difficult.

The value of the human milk fat globule membrane antigen HMFG2 in epithelial ovarian cancer monitoring: comparison with CA125

We assayed serum HMFG2 in serial samples from 215 primary epithelial ovarian cancer patients using an 'in-house' single determinant ELISA, 45% of patients with stage I, 54% with stage II, 61% with stage III and 75% with stage IV disease had elevated serum HMFG2. Post-operative levels were significantly related with residual tumour volume (P < 0.005), and fell in the majority of responders, although the association with response to first-line chemotherapy was not significant. HMFG2 had a sensitivity of 50% specificity of 83%, accuracy of 61%, PVP of 86% and PVN of 45% for disease at second-look laparotomy. Serial levels gave a lead time to clinical relapse in 47% of patients who responded to therapy, including one patient with negative CA125 levels. HMFG, paralleled CA125 in many respects, although it was elevated in fewer patients. In a stepwise discriminant analysis, HMFG2 added to the discrimination of CA125 (r = 0.183, P < 0.005), although additional accurate information was only given in patients with advanced poorly differentiated serous cystadenocarcinoma. Given that HMFG2 is expressed in few patients who are CA125 negative it is unlikely that it will have a significant clinical impact upon patient management.

Studies of a tumor-associated antigen, COX-1, recognized by a monoclonal antibody

Monoclonal antibodies against an ovarian tumor cell line, OC-3-VGH, were generated using modified hybridoma technology. Among the seven that were selected for their high specificity and affinity to ovarian cancer cells and low cross-reactivity to most normal human tissues, RP 215 was shown to react specifically with a tumor-associated antigen, COX-1, from certain ovarian/cervical cancer cell lines. By Western blot assay, COX-1 was shown to have a subunit molecular mass of about 60 kDa and exist as an aggregate in the native state. COX-1 could also be detected in the shed medium of certain cultured tumor cells. A solid-phase sandwich enzyme-immunoassay procedure was designed for quantitative determinations of COX-1 in the shed medium or in patients' sera using RP 215 for both well-coating and the signal detection. Highly purified COX-1 was obtained from the shed medium of cultured OC-3-VGH tumor cells mainly by hydroxyapatite and immunoaffinity chromatography with RP 215 as the affinity ligand. At neutral pH, purified COX-1 also exists as an aggregate and is relatively stable at temperatures below 50 degrees C. Its immunoactivity was found to decrease with time in the presence of trypsin. However, the immunoactivity of COX-1 was not affected upon incubation with carbohydrate-digestive enzymes or concanavalin A and only partially inactivated in the presence of NaIO4 or iodoacetamide. Treatments of COX-1 with dithiothreitol and guanidine thiocyanate resulted in a complete loss of activity. Furthermore, rabbit antisera raised against purified COX-1 exhibited similar immunospecificity to that of RP 215. The results of this study suggest that COX-1 is a glycoprotein consisting of a 60 kDa subunit, which is recognized by RP 215 through its peptide determinant. Preliminary retrospective clinical studies were performed to assess the utility of a COX-1 enzyme immunoassay kit for detection and monitoring of patients with ovarian and cervical cancers.

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.

Carcinomatous meningitis: antibody-guided therapy with I-131 HMFG1

Seven patients with carcinomatous meningitis were administered intrathecal I-131 labelled monoclonal antibody HMFG1. Clinical responses were seen in two patients, with a long term survivor at 32 months. Aseptic meningitis occurred in 4/7 patients, but more serious toxicity was observed in the form of seizures (2/7 patients) and myelosuppression (3/7 patients). Partial obliteration of the subarachnoid space was identified as a potential problem in patients with advanced disease.

Evaluation of two new assays for tumor-associated antigens, CASA and OSA, found in the serum of patients with epithelial ovarian carcinoma--comparison with CA125

Two new assays have been developed to measure tumor-associated antigens designated ovarian serum antigen (OSA) and cancer-associated serum antigen (CASA). Both assays are dual epitope ELISAs using the same capture monoclonal antibody (BC2); the second antibodies in the OSA and CASA assays are OM-1 and BC3, respectively. Using arbitrary cutoffs of 2.5 and 3.0 units/ml, 82 and 76% of 80 serum samples from ovarian cancer patients were positive for OSA and CASA, respectively, compared with 5 and 2.5% of samples from a control population of 40 women. A strong correlation was found between the two assays (r = 0.80, P less than 0.001). CA125 levels were obtained from 49 of the 80 samples; 82% of these samples were positive for CA125 (greater than 35 U/ml), 82% for OSA and 73% for CASA. Of the 9 samples negative for CA125, 3 were positive for OSA and 3 were positive for CASA. Serum OSA, CASA, and CA125 levels were determined in serial samples from 20 ovarian carcinoma patients throughout the course of their treatment. Clinical course was accurately reflected by CA125 levels in 85% of patients, by CASA in 65%, and by OSA in 75%. In 4 patients, a rise in CASA levels and, in 2 patients, a rise in OSA levels significantly predated rising CA125 levels to predict recurrence. Six of 7 serum samples obtained prior to positive second-look laparotomy were negative for CA125, while 4 were positive for OSA and 6 were positive for CASA. These results indicate that the OSA and CASA assays could be superior to CA125 for detection of small volume occult ovarian carcinoma.

HMFG1 antigen: a new marker for carcinomatous meningitis

Carcinomatous meningitis is a devastating metastatic complication of systemic carcinoma, which may occur insidiously, accompanied by a confusing spectrum of clinical symptoms and signs. In the absence of reliable diagnostic tumour markers, the diagnosis is established by the demonstration of malignant cells within the cerebrospinal fluid (CSF). Cytological techniques requiring skillful interpretation are occasionally negative in the presence of established disease, and when positive may indicate leptomeningeal malignancy of such advanced nature that effective palliation is difficult. Biochemical tumour marker technology offers the potential of reliable diagnosis in early disease states, prior to the appearance of exfoliated malignant cells. In a series of 100 patients, we assayed for an epithelial associated glycoprotein (HMFGI antigen) in CSF obtained at lumbar puncture. In 18 of 20 patients with carcinomatous meningitis, this high-molecular-weight glycoprotein was detectable in the CSF. The antigen was also present in 2 patients with neoplastic meningitis complicating lymphoma and medulloblastoma, but was not detected in the CSF of the remaining 78 patients.

Expression of multiple tumour markers in serum from patients with ovarian carcinoma and healthy women

Serum samples from 70 patients with bulky ovarian carcinomas, 46 patients with surgically extirpated Stage I ovarian carcinomas, and 108 aged-matched healthy control subjects were assayed for 10 tumour-associated antigens. Levels of expression of each antigen were progressively increased in treated Stage I and bulky disease patients over healthy controls. Levels of expression in treated Stage I patients inversely reflected the interval between surgery and collection of the sample. For patients with bulky disease, determination of correlation coefficients of expression of each antigen against each other antigen showed that in 9 of 45 such relationships, the coefficients were greater than 0.30, suggesting significant coexpression. The best correlation was found for CA125 and MSA, HMFG2 and MSA, DCA and MSA, and DCA and HMFG2. By multivariate discriminant function analysis, the combination of 2 assays (CA125 and NB/70K) was found to increase specificity of detection of ovarian carcinoma over one assay alone (CA125). Use of more than these 2 assays increased sensitivity only marginally. The attained specificity is insufficient for use as a screening assay for ovarian cancer alone, given the low prevalence in the community of this disease.

Biological properties of ten human ovarian carcinoma cell lines: calibration in vitro against four platinum complexes

Ten human ovarian carcinoma cell lines have been studied as a potential in vitro screen for the development of novel anticancer platinum complexes. Lines have been established and developed both from solid and ascitic tumours, from pretreated and untreated patients, and are available at a range of in vitro passage numbers. The biological properties of the lines were consistent with them being human, epithelial and of ovarian carcinoma origin. Using a tritiated thymidine or leucine uptake method, and a 96 hour continuous drug exposure, the lines have been calibrated against four platinum-containing chemotherapeutic agents: cisplatin, iproplatin, carboplatin and tetraplatin. Striking differences in cytotoxicity were observed across the lines for each agent. Some lines were consistently resistant, others generally sensitive, whereas some showed clear evidence of differential sensitivity to a particular agent. Statistical analysis (Spearman rank correlation) involving the six possible pairings of drugs showed that cisplatin, iproplatin and carboplatin elicit a very similar pattern of response in these lines whereas tetraplatin elicits a completely different response pattern. Similar cytotoxicity values were obtained using a soft agar cloning assay. Results using a tetrazolium dye reduction assay, however, gave somewhat higher and more variable values, particularly with tetraplatin. The thymidine uptake assay will be adopted in further studies on a selected panel of six lines. This panel encompasses the spectra of sensitivities identified for each of the four agents against the original ten lines and may provide a useful screening facility for the development of novel platinum drugs, in that it detects both cell line-determined and structure-determined differences in cytotoxicity.

Aminoterminal propeptide of type-III procollagen in serum--an indicator of clinical behavior of advanced ovarian carcinoma?

In ovarian carcinoma, elevated serum concentrations of the aminoterminal propeptide of type-III procollagen are related to the clinical stage of the disease and to the presence of ascites, which contains very high concentrations of the propeptide. In a follow-up of patients with advanced disease, favorable clinical course was associated with normalizing propeptide values, whereas in progressing disease the values increased several weeks before clinical progression. In stable disease the concentrations were constantly above the reference range. Laminin and type-IV-collagen-related serum antigens were mostly within the reference range.

A 72 kD trophoblast glycoprotein defined by a monoclonal antibody

A novel trophoblast cell surface antigen has been defined by a monoclonal antibody 5T4, raised following immunisation with wheat germ agglutinin (WGA) purified glycoproteins from deoxycholate (DOC) solubilised human syncytiotrophoblast plasma membrane (StMPM). The distribution of the antigen was determined by indirect immunoperoxidase staining of sections of normal organ and placental tissues as well as immunofluorescence and radiobinding assays with a wide variety of cell lines representing differing normal and tumour cell types. In frozen sections of normal full term placenta, 5T4 is strongly expressed only by the syncytiotrophoblast, some extravillous cytotrophoblast and the amniotic epithelium. The 5T4 antigen is apparently not expressed by any maternal component of the placenta nor is it detected in adult liver, lung, bronchus, heart, testis, ovary, brain, or muscle. The antigen is apparently expressed by several specialised epithelia. Immunoprecipitation of radiolabelled StMPM indicated that 5T4 molecules are glycoproteins of mol. wt of approximately 72 kD on SDS-PAGE. 5T4 antigen is selectively expressed by diverse tumour cell lines, including those of developmental origin. The molecular characteristics, relatively restricted normal tissue distribution and expression by certain tumour cell types make this antigen worthy of future study for use as a diagnostic marker of malignancy.

Elevated serum HMFG antigen levels in breast and ovarian cancer patients measured with a sandwich ELISA

HMFG antigen is a tumour associated glycoprotein that has been immunohistochemically shown to be expressed by malignant cells in breast and ovarian and to a lesser degree in gastro-intestinal carcinomas. We have developed a non-isotopic sandwich ELISA for secretory HMFG antigen utilizing a polyclonal catcher and a tracer monoclonal antibody (MAb). 52/52 of healthy medical students (controls) had a serum value under 400 U/ml whereas 15/30 patients (50%) with evident ovarian cancer and 13/37 (35%) with advanced breast cancer had a value exceeding 400 U/ml. From other patients with malignant tumours 2/14 (14%) with endometrial carcinoma, 0/5 with cervical carcinoma, 0/5 with vulvar carcinoma, 1/33 with gastro-intestinal carcinoma, 0/4 with oesophageal carcinoma and 2/45 of patients with leukemia or lymphoma had an elevated serum HMFG value. Four cases of Crohn disease, 3 cases of ulcerative colitis and 2 cases of pelvic inflammatory disease all showed a serum value below 400 U/ml. Progression of ovarian cancer was accompanied by increasing serum HMFG antigen levels. The antigen detected by our assay is different from CA 125 but may be related with the tumour associated antigen CA 15-3.

Patterns of expression of a tumor associated antigen, defined by the monoclonal antibody HMFG2, in human epithelial ovarian carcinoma. Comparison with expression of the HMFG1, AUA1 and F36/22 antigens

Binding to the antigen defined by the monoclonal antibody HMFG2 was demonstrated in more than 94% of human epithelial ovarian carcinomas by the indirect immunoperoxidase technique. The extent of the expression of this antigen related to tumor differentiation; well-differentiated tumors expressed more antigen than poorly differentiated tumors. Marked variation of tumor grade and antigen expression was demonstrated in individual tumors and this may be a limiting factor in the use of radioisotope linked HMFG2 for tumor therapy. A similar prevalence was found in the expression of the antigens defined by the monoclonal antibodies HMFG1 and F36/22; whereas the AUA1 antigen was demonstrated in 68% of cases. The patterns of expression of the HMFG1, HMFG2, and F36/22 antigens suggest that they may be related antigens.