Comparison of percent free PSA, PSA density, and age-specific PSA cutoffs for prostate cancer detection and staging.

OBJECTIVES: Various methods have been proposed to increase the specificity of prostate-specific antigen (PSA), including age-specific PSA reference ranges, PSA density (PSAD), and percent free PSA (%fPSA). In this multicenter study, we compared these methods for their utility in cancer detection and their ability to predict pathologic stage after radical prostatectomy in patients with clinically localized, Stage T1c cancer. METHODS: Seven hundred seventy-three men (379 with prostate cancer, 394 with benign prostatic disease), 50 to 75 years old, from seven medical centers were enrolled in this prospective blinded study. All subjects had a palpably benign prostate, PSA 4.0 to 10.0 ng/mL, and a histologically confirmed diagnosis. Hybritech's Tandem PSA and free PSA assays were used. RESULTS: %fPSA and age-specific PSA cutoffs enhanced PSA specificity for cancer detection, but %fPSA maintained significantly higher sensitivities. Age-specific PSA cutoffs missed 20% to 60% of cancers in men older than 60 years of age. %fPSA and PSAD performed equally well for detection (95% sensitivity) if cutoffs of 25% fPSA or 0.078 PSAD were used. The commonly used PSAD cutoff of 0.15 detected only 59% of cancers. %fPSA and PSAD also produced similar results for prediction of the post-radical prostatectomy pathologic stage. Patients with cancer with higher %fPSA values (greater than 15%) or lower PSAD values (0.15 or less) tended to have less aggressive disease. CONCLUSIONS: The results of this study demonstrated that cancer detection (sensitivity) is significantly higher with %fPSA than with age-specific PSA reference ranges. %fPSA and PSAD provide comparable results, suggesting that %fPSA may be used in place of PSAD for biopsy decisions and in algorithms for prediction of less aggressive tumors since the determination of %fPSA does not require ultrasound.

A new biomarker in monitoring breast cancer: CA 549.

Serum biomarkers are not very reliable in assessing outcome or predicting recurrence of breast cancer. Clinically, carcinoembryonic antigen (CEA) is widely used and is elevated in a majority of patients with metastatic breast cancer. However, it is falsely elevated in a wide range of nonmalignant conditions and correlates poorly with disease progression. We evaluated a newly described monoclonal antibody, CA 549, in an immunoradiometric assay which uses two monoclonal antibodies directed against tumor and milk fat globule membranes. CA 549 and CEA were studied in 682 patients, 331 of whom had breast diseases and 99 of whom were followed with multiple serum samples. Of 69 patients with benign breast diseases, 1.5% had elevated CA 549, 0% of 30 pregnant women had elevated CA 549, and 26% of patients with nonmalignant liver disease had CA 549 elevation. In metastatic cancer of prostate, ovary, endometrium, colon, and lung CA 549 was elevated in 12% to 50% of cases with levels less than 120 U/mL. In breast cancer, CA 549 was elevated in 11% of 88 patients who received adjuvant chemotherapy and had no evidence of metastasis; in 23% of 16 patients in complete remission after chemotherapy; in 63% of 52 patients in partial remission after therapy; and in 83% of 106 patients with progression of breast cancer compared with 63% with elevated CEA (P = .001). In diseases of the breast, CA 549 has a sensitivity In diseases of the breast, CA 549 has a sensitivity and specificity of 77% and 92% v 61% and 92% for CEA. Of 99 patients serially monitored with clinically documented breast cancer progression, regression, or stability of disease, CA 549 was statistically significantly superior to CEA in monitoring a greater than 25% change in those patients with metastatic progression (P = .03). CA 549 is a new serum marker that should be control tested in prospective clinical trials alone or in conjunction with other markers.

Monitoring breast cancer with CA 549.

CA 549, a new marker for breast cancer, was measured in serum of 719 patients by an immunoradiometric assay involving two monoclonal antibodies: BC4E 549, developed against a breast-tumor cell line, and BC4N 154, developed against milk fat-globule membrane. The reference interval for healthy women was 0-11 kilo-units/L. The percentages of patients with CA 549 greater than 11 kilo-units/L for benign conditions are: 0% pregnancy, 1% breast, 26% liver; and for nonbreast metastatic cancers: 12% endometrial, 33% lung, 40% prostatic, and 50% ovarian. In women with breast cancer who were receiving or had completed adjuvant therapy with no evidence of disease there was an 11% increase in CA 549. For patients with metastatic breast cancer, 19% of those in complete remission, 63% of those in partial remission, and 88% of those with systemic progression had increased CA 549. CA 549 is a more specific marker than carcinoembryonic antigen (CEA) in nonmalignant disease, nonbreast malignancies, and adjuvant breast-cancer patients, and it is more sensitive in breast-cancer patients with progressive disease than is CEA. We could show CA 549 to be superior to CEA for detecting active breast cancer in patients with malignant or nonmalignant breast diseases. In monitoring 19 adjuvant-treated patients, CA 549 correlated more closely with the clinical course than did CEA values and, when increased, predicted a clinical recurrence. In 18 breast-cancer patients with metastasis, monitored for two to three years, the change of CA 549 values paralleled disease courses more often than did CEA values.

Serum levels and biochemical characteristics of cancer-associated antigen CA-549, a circulating breast cancer marker.

CA-549 is a circulating breast cancer-associated antigen that reacts with monoclonal antibody BC4E 549. Biochemical characterization of CA-549 revealed that it is an acidic (isoelectric point 5.2) glycoprotein that exhibits two bands by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions of apparent molecular weights of 400,000 and 512,000. Immunohistochemical staining of unfixed frozen tissue sections of human breast tumors and a variety of benign tissues with BC4E 549 revealed no preferential staining of tumor over benign breast tissue and cross-reactivity with a wide range of other benign tissues including kidney, liver, lung, colon, pancreas, ovary, and spleen. Serum levels of CA-549 were initially tested by an enzyme-linked immunosorbent assay inhibition using BC4E 549. This assay showed that CA-549 concentrations were elevated in 19 of 27 sera from patients with advanced breast cancer compared to 0 of 22 and 0 of 129 sera from benign breast disease patients and healthy females, respectively. These preliminary data suggested that CA-549 was a useful breast tumor marker; thus BC4E 549 was adapted to a sandwich immunoradiometric assay format suitable for routine use in the clinical laboratory and its performance was evaluated on a panel of 668 serum samples. The test detected significant concentrations of CA-549 in the sera of 40 of 80 patients with advanced breast cancer, 1 of 30 with early breast cancer, 4 of 19 with advanced lung cancer, 2 of 40 with advanced colon cancer, and 5 of 29 with advanced prostate cancer. The test showed a high degree of specificity, producing false-positives in only 3 of 79 benign breast patients, 2 of 25 benign liver patients, 2 of 70 benign colon patients, 2 of 19 benign lung patients, 0 of 20 benign prostate patients, and 3 of 257 healthy individuals. These data represent an overall 50% sensitivity and 98% specificity as a test for advanced breast cancer. These data indicate that this immunoradiometric assay is a useful test for the detection of circulating CA-549 in advanced breast cancer patients and suggest that it may prove useful as a monitor in the management of that disease.

Tissue localization and biochemical characteristics of a new thymic antigen recognized by a monoclonal thymocytotoxic autoantibody from New Zealand black mice.

Naturally occurring thymocytotoxic autoantibodies (NTA) have been described in both humans and mice with SLE. To define further the role of anti-thymic autoantibodies in murine lupus, we studied the cellular and molecular specificity of a spontaneous monoclonal NTA, designated TC-17, derived from a 4-mo-old New Zealand Black mouse. TC-17, an IgM autoantibody, has been shown previously to be unreactive with Lyt-1, Lyt-2, and L3T4 (T helper) antigens. We have shown further that it is also unreactive with Thy-1. TC-17 recognizes a new thymic antigen that appears to mark a distinct subpopulation of cortisol-sensitive cortical thymocytes. The antigen consists of a single glycoprotein chain with an apparent m.w. of 88,000. TC-17 shows reduced binding to thymocytes treated with tunicamycin, indicating either that glycosylation of TC-17 antigen is necessary for TC-17 to bind to it or that glycosylation is required for expression of the antigen on the cell surface. TC-17 uniquely reacts with two of 17 murine lymphoid tumor cell lines of intermediate cellular maturity. The thymocytotoxic activity of TC-17 is absorbed by single cell suspensions of murine stomach, small intestine, large intestine, kidney, and thymus. Moreover, the specific binding of TC-17 to gut tissue of normal and germfree mice can be demonstrated by indirect immunofluorescence, suggesting antigenic cross-reactions between thymic and gut tissue. TC-17 reacts with rat thymocytes as well as it does with murine cells, indicating moderate evolutionary conservation of the TC-17 antigen. The expression of this glycoprotein by a discrete thymocyte subset may prove to be a valuable probe for the study of murine T cell differentiation.

Characteristics of a spontaneous monoclonal thymocytotoxic antibody from New Zealand Black mice: recognition of a specific NTA determinant.

Naturally occurring thymocytotoxic autoantibodies (NTA) have been described both in humans and in mice with SLE, and have been reported to be preferentially reactive with T suppressor as compared to T helper cells. However, although NTA has been shown by some groups of investigators to induce autoantibodies in normal strains of mice, other researchers have suggested that NTA has only a minor, if any, role in murine lupus. We have been studying the characteristics of a monoclonal antibody (TC-17) derived from the fusion of 4-mo-old NZB spleen cells with P3-X63-AG8.653 plasmacytoma cells. This monoclonal IgM reagent is cytotoxic for approximately 40% of total thymocytes, 50% of cortical thymocytes, less than 1% of cortisol-resistant thymocytes, 10% of splenocytes and lymph node cells, and less than 3% of bone marrow and fetal liver cells. The thymocytotoxicity can be absorbed by thymocytes but not by brain cells. Although NZB, NZW, NFS, and BALB/c thymocytes all manifest reactivity with TC-17, there was considerable difference between strains with respect to antigen density; NZB thymocytes have the highest density. By FACS analysis, TC-17 occurs independently of Lyt-1, Lyt-2, and T helper cell-specific antigens, and is more prevalent on larger proliferating thymocytes. TC-17 augments the response to SRBC but does not influence responses to TI-1 (TNP-BA) or TI-2 (DNP-Ficoll) antigen and production of LPS-induced B cell colonies. We believe that TC-17 recognizes a new T cell antigen, probably one involved in T cell differentiation. Because this monoclonal NTA reacts with only 40% of thymocytes, and is not absorbed with brain, it would not have been detected in mouse sera by using previously published methods. NTA are a heterogeneous group of autoantibodies; some specificities such as TC-17 went unrecognized in the past, and may be important either for disease pathogenesis or for secondary immunologic abnormalities.

Studies of congenitally immunologically mutant New Zealand mice. IX. Age-related microenvironmental effects on autoantibody production in NZB and NZB.Xid mice studied by transplantation.

The mechanism of polyclonal expansion of B cells and subsequent autoantibody production in New Zealand mice remains a critical question. We have been studying the requirements for autoantibody production both in NZB mice as well as NZB mice congenic with the Xid gene of CBA/N mice. In this study, we have attempted to alter the immunologic phenotype of NZB.Xid mice by transfer of cells from young and old NZB mice. There was little difficulty in restoring normal levels of serum IgM, IgG3, splenic Lyb-5 cells, and response to DNP-Ficoll in young NZB.Xid mice that were injected with young NZB bone marrow cells. Although such animals had an almost immediate change in their immune profile to values characteristic of NZB mice, they required, much like unmanipulated NZB mice, a latency period of an additional 6 mo before autoantibodies were detected. In contrast, adult NZB.Xid mice, who likewise developed an immune profile similar to NZB after transfer of bone marrow cells from young NZB mice, began to express autoantibodies immediately without any latency period. NZB.Xid mice who were recipients of adult NZB bone marrow cells did not show sustained autoantibody production, reflecting the limited state of B cell precursors in adult NZB mice. Thus, the age of both donor cells and the age of recipient mice are critical factors for determining the latency period and the age at which autoantibodies will appear. Similarly we attempted to alter the production of autoantibodies in NZB mice that were irradiated and injected with bone marrow cells from NZB.Xid animals. NZB mice had a major amelioration of disease when they received cell transfers from young NZB.Xid mice. This amelioration, which included the acquisition of the immune profile of NZB.Xid animals, was not seen in adult NZB mice that were recipient of young NZB cells. We suggest that although Lyb-5 cells may be the effective mechanism for autoantibody production, there are other interacting influences that may selectively turn on or turn off autoantibodies and that are required and are responsible for the latency period.

Induction of erythrocyte autoantibodies in NZB mice: spectrotype and relationship with the Xid gene.

The production of autoantibodies to erythrocytes by immunization with rat red blood cells (RRBC) is significantly retarded in X-linked immune deficient (Xid) mice. We have attempted to further explore this relationship by characterizing RRBC-induced erythrocyte autoantibodies in high responder New Zealand Black (NZB) and congenic NZB.Xid mice. NZB.Xid animals, immunized with RRBC, readily produce anti-RRBC antibodies and cross-reactive antiautologous erythrocyte antibody (CR anti-MRBC) as well as anti-HB antibodies. The autoantibody response of NZB.Xid mice to RRBC appears similar to NZB controls with respect to both the time of onset and subclass diversity; the anti-HB antibody cannot be absorbed with RRBC. Moreover, there are no alterations in the spectrotype of antierythrocyte antibodies found in NZB.Xid mice. Nonetheless, NZB.Xid, but not NZB mice, fail to produce splenic plaque-forming responses against bromelase-treated mouse red blood cells. Lyb 5+ cells are not required for the production of RRBC-induced antierythrocyte autoantibodies. These results, when discussed in light of the low but significant incidence of spontaneous DAT in NZB.Xid mice, suggest that given the appropriate genetic repertoire, the influence of the Xid gene on autoantibody production can be bypassed.

Studies of congenitally immunologically mutant New Zealand mice. VIII. Cell-surface phenotype of spleen cells of Xid and nude mice.

Surface immunoglobulin on spleen cells from NZB and NZB/W mice and congenic mice bearing the nude or X-linked immune defective (Xid) gene was examined by flow microfluorometry with regard to both the frequency of positive cells and density expressed on the cell. These data indicate that although the frequency of unseparated sIg+ B lymphocytes is equivalent among all of these groups of mice, the densities of sIgM and sIgD are different. Spleen cells from these mice were also separated by free-flow electrophoresis and analyzed in a similar manner. This analysis demonstrated the absence of a subpopulation of B lymphocytes with a low electrophoretic mobility and low expression of sIgM. These studies suggest that maturational and/or activation states of the B cells in mice bearing the Xid or nude genes are different from those seen in the parent strains of mice. Such alterations in cell-surface antigens correlate with the differences in the natural history of immunopathology of the autoimmune disease in these congenic colonies of New Zealand mice.