Significance of serum CA125 and TPS antigen levels for determination of overall survival after three chemotherapy courses in ovarian cancer patients during long-term follow-up.

PURPOSE OF INVESTIGATION: To evaluate the prognostic significance for overall survival rate for the marker combination TPS and CA125 in ovarian cancer patients after three chemotherapy courses during long-term clinical follow-up. METHODS: The overall survival of 212 (out of 213) ovarian cancer patients (FIGO Stages I-IV) was analyzed in a prospective multicenter study during a 10-year clinical follow-up by univariate and multivariate analysis. RESULTS: In patients with ovarian cancer FIGO Stage I (34 patients) or FIGO Stage II (30 patients) disease, the univariate and multivariate analysis of the 10-year overall survival data showed that CA125 and TPS serum levels were not independent prognostic factors. In the FIGO Stage III group (112 patients), the 10-year overall survival was 15.2%; while in the FIGO Stage IV group (36 patients) a 10-year overall survival of 5.6% was seen. Here, the tumor markers CA125 and TPS levels were significant prognostic factors in both univariate and multivariate analysis (p < 0.0001). In a combined FIGO Stage III + FIGO Stage IV group (60 patients with optimal debulking surgery), multivariate analysis demonstrated that CA125 and TPS levels were independent prognostic factors. For patients in this combined FIGO Stage III + IV group having both markers below respective discrimination level, 35.3% survived for more than ten years, as opposed to patients having one marker above the discrimination level where the 10-year survival was reduced to 10% of the patients. For patients showing both markers above the respective discrimination level, none of the patients survived for the 10-year follow-up time. CONCLUSION: In FIGO III and IV ovarian cancer patients, only patients with CA 125 and TPS markers below the discrimination level after three chemotherapy courses indicated a favorable prognosis. Patients with an elevated level of CA 125 or TPS or both markers after three chemotherapy courses showed unfavorable prognosis.

Characterization of monoclonal antibodies directed against squamous cell carcinoma antigens: report of the TD-10 Workshop.

Thirteen monoclonal antibodies directed against squamous cell carcinoma antigens (SCCA1 and SCCA2) were obtained from five international collaborating laboratories participating in the ISOBM TD-10 Workshop. Native and recombinant forms of SCCA were used in a wide variety of approaches to determine the reactivity and specificity of these antibodies. Based on reactivity, the antibodies could be divided into three groups: the SCCA1-reactive group containing those that reacted only with recombinant SCCA1 (rSCCA1) and native SCCA1 (nSCCA1) antigens, the SCCA2-reactive group containing those that reacted only with recombinant SCCA2 (rSCCA2), and the pan-reactive group containing those antibodies that reacted with rSCCA1, nSCCA1, and rSCCA2. Binding to radioiodinated rSCCA1 showed that all reactive antibodies were of a high affinity (K(d) <2 x 10(-9) mol/l). Binding to labelled rSCCA2 demonstrated that five antibodies were of a high affinity (K(d) <2 x 10(-9) mol/l). Antibody reactivity on Western blots was tested with nonreduced and reduced native and recombinant SCCA1 and SCCA2. In general, these findings showed that reduction had little effect on binding to SCCA1, but often a strong effect on the binding to SCCA2. Binding of antibodies to rSCCA1 and rSCCA2 in complexes with cathepsin L and G, respectively, was used to assist in the localization of epitope regions in enzyme-complexed SCCA. Cross-inhibition experiments showed that SCCA1-reactive antibodies represent two different epitope groups, and this is supported by their ability to make SCCA1-specific assays by combining antibodies from the two epitope groups. The SCCA2-reactive group represents two related antibodies and one unique as seen in cross-inhibition, but they do not form successful assay combinations. Classification of the pan-reactive antibodies is more difficult, as some epitope groups differ when results from rSCCA1 are compared with rSCCA2 as the target. However, two antibodies are outstanding, SCC107 and SCC113, as they are high-affinity antibodies which react equally well with free and protease complexes of SCCA1 and SCCA2. The precise location of epitopes was further studied using sequential overlapping peptides and homology modelling. The findings from this workshop strongly indicate that the recombinant antigens (rSCCA1 and rSCCA2) are very similar in epitope structure to the native counterparts in saliva, and squamous epithelium from normal and cancer tissues. Therefore, it is reasonable to conclude that the specificities found are reliable and have application for antibody measurement of all forms of squamous cell carcinoma in serum except SCCA2 in complex with its protease.

Sample preparation of human serum for the analysis of tumor markers. Comparison of different approaches for albumin and gamma-globulin depletion.

LC-MS is a powerful method for the sensitive detection of proteins and peptides in biological fluids. However, the presence of highly abundant proteins often masks those of lower abundance and thus generally prevents their detection and identification in proteomic studies. In human serum the most abundant proteins are albumin and gamma-globulins. We tested several approaches to specifically reduce the level of these proteins based on either specific antibodies, dye ligands (for albumin) and protein A or G (for gamma-globulins). The resulting, depleted serum was analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis and LC-MS for the residual presence of these abundant proteins as well as for other serum proteins that should remain after depletion. To test the applicability of this method to real-life samples, depleted serum of a cervical cancer patient was analyzed for the presence of a specific tumor marker protein SCCA1 (squamous cell carcinoma antigen 1; P29508), which is present at ng/ml concentrations. The results demonstrate that SCCA1 can be detected by LC-MS in patient serum following depletion of albumin and gamma-globulins thus opening the possibility of screening patient sera for other, so far unknown, tumor markers.

Epitopes on CA 125 from cervical mucus and ascites fluid and characterization of six new antibodies. Third report from the ISOBM TD-1 workshop.

CA 125 is found in body fluids in a variety of molecular weight forms. The largest species are found in normal abdominal fluid and cervical mucus. The present study therefore incorporated CA 125 derived from these sources as well as ascites fluid to investigate if the source of CA 125 influenced epitope characterization. Ascites-derived CA 125 varied in size from about 190 to about 2,700 kD. Cervical mucus-derived CA 125 treated with ultrasound changed its apparent size from more than 20,000 to 700 kD. Epitope mapping of antibodies was not grossly influenced by the size or source of CA 125 used as target. However, low-molecular-weight CA 125, i.e. ascites fractions CA 17/E, CA 17/F and CA 10/7, did show differences in certain assay combinations and cross-inhibition patterns which probably can be explained by steric effects due to the smaller size compared with the most abundant forms of CA 125 present in serum and other body fluids. The specificity of six new monoclonal antibodies to CA 125 was tested by cross-inhibition and immunometric assay combinations and compared to reference antibodies. One antibody, X306, belonged to the OC125-like antibodies. Four antibodies, X52, X75, X325 and VK8, were M11-like. The sixth antibody, 7C12, reacted with an epitope which was difficult to define. This antibody was inhibited by M11-like antibodies and OV197. However, used as an inhibitor, 7C12 inhibited only itself. We grouped it as an OV197-like antibody, but clearly different from OV197. The topography of epitopes was studied by analyzing all antibody pairs in immunoradiometric assays. These results confirmed the grouping of antibodies described above and are in accordance with previous findings that the highest signal is obtained using an OC125-like antibody or OV197 on the solid phase and an M11-like antibody as tracer. The composition of the sample in terms of high- and low-molecular-weight species of CA 125 was measured, with different responses depending on the antibody pair used. This might be one reason for discrepancies between assay results for CA 125 using different assays.

CA 125 in serum and tumor from patients with uterine sarcoma.

Serial serum samples of 33 patients with primary sarcoma of the uterus were analyzed for CA 125 and frozen tissue sections of tumor from 23 patients were tested for this antigen. Before treatment, 12 of 30 evaluable patients showed serum CA 125 levels> 16 Uml-1 (40%). There was no relationship between serum CA 125 level and the histologic subtype. Patients with serum CA 125> 16 Uml-1 showed extrauterine tumor sites in 67% of the cases versus 33% in patients with normal CA 125 determinations (P = 0.026). In (FIGO) stages I and II, elevated serum CA 125 levels prior to surgery were associated with a poor prognosis (P = 0.043). Patients with recurrent or progressive disease demonstrated serum CA 125 levels> 16 Uml-1 in 14 of the 20 cases (70%). Sarcoma cells were completely negative for CA 125, whereas positivity was observed in the epithelial component of mixed Müllerian tumors. The source of the elevated serum CA 125 levels in patients with uterine sarcoma may be stimulated mesothelial cells.