Abstract P2-09-07: Elevated Pretreatment Serum CA9 (CAIX) (Carbonic Anhydrase 9) Predicts Reduced Progression-Free and Overall Survival in Trastuzumab-Treated Metastatic Breast Cancer

Background: Approximately one-half of HER2-positive breast cancer patients will respond to first-line trastuzumab-containing therapy. However, in those patients with an initial trastuzumab response, most will progress within a year with acquired resistance. Since trastuzumab treatment is also now used in the HER2-positive adjuvant breast cancer setting, trastuzumab resistance will continue to be a vexing clinical problem, and better predictive and prognostic biomarkers are urgently needed. Methods: Serum HER2, tissue inhibitor of metalloproteinase-1 (TIMP-1), urokinase-type plasminogen activator (uPA), CA9, Insulin-like growth factor-1 receptor (IGF-1R), VEGF-165, and endoglin were measured using ELISA assays in 60 metastatic breast cancer patients before starting first-line trastuzumab-containing therapy. The HER2, TIMP-1, uPA, CA9, IGF-IR, and VEGF-165 ELISAs were from Oncogene Science/Siemens Healthcare Diagnostics, Cambridge, MA; and the endoglin ELISA was from R&D Systems, Minneapolis, MN. Progression-free survival (PFS) and overall survival (OS) were analyzed using the Kaplan-Meier method and Cox modeling with continuous pretreatment serum biomarker variables.

Results: Pretreatment serum HER2 (p= 0.008), TIMP-1 (p< 0.0001), uPA (p= 0.006), endoglin (p= 0.010), and CA9 (p <0.0001) were all significant as univariate continuous biomarkers for predicting PFS to first-line trastuzumab-containing therapy, but VEGF (p=0.94) and IGF-IR (p=0.11) were not. In multivariate analysis for PFS with all 7 biomarkers, only serum CA9 (p= 0.002) was a significant independent covariate. For OS, pretreatment serum HER2 (p= 0.018), TIMP-1 (P<0.0001), uPA (P<0.0001), endoglin (0.006), CA9 (P<0.0001) were all significant as univariate continuous biomarkers for prognosis, but VEGF (p=0.69) and IGF-IR (p=0.098) were not. In multivariate analysis for OS with all 7 biomarkers, only serum CA9 was a significant independent prognostic covariate (p=0.001), and TIMP-1 trended significant (p=0.069). Conclusions: Elevated pretreatment serum CA9 (a marker of hypoxia) predicts reduced progression-free survival and overall survival in metastatic breast cancer patients treated with first-line trastuzumab-containing therapy. These serum biomarkers deserve further study in larger trials of HER2-targeted breast cancer treatment. Supported by a grant from Komen for the Cure.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-09-07.

Examination of TIMP-1 Levels and Relapse-Free Survival for Patients in NCIC CTG MA.14 Who Received Adjuvant Tamoxifen +/- Octreotide LAR

Background: Tissue inhibitor of metalloproteinase-1 (TIMP-1) has been shown to have diverse multifunctional roles in tumorigenesis. AL/KL/SA postulated from first line metastatic endocrine therapy that elevated pre-treatment serum TIMP-1 required additional therapy. NCIC CTG MA.14 adjuvant endocrine trial permitted examination of whether TIMP-1 serum levels post-chemotherapy was associated with RFS. Methods: NCIC CTG MA.14 is a trial where 667 postmenopausal patients were randomized to receive adjuvant tamoxifen +/- octreotide LAR with a stratification factor of no, concurrent or sequential chemotherapy. For the purposes of this work, this was simplified to whether a patient had or had not received adjuvant chemotherapy prior to the serum draw. Serum TIMP-1 was assessed on >90% of the trial patients. We examined the effect of baseline TIMP-1 levels on relapse-free survival (RFS) of 1) all types, 2) bone only, 3) all types of bone, and 4) non-bone, by timing of chemotherapy before the serum draw utilizing continuous TIMP (ng/ml) and categorical TIMP (<454, >454 ng/ml, based on 95% non-parametric cut-point for healthy post-menopausal females). Data were available on patient and tumour characteristics of age (years), pathologic tumour size (cm), pathologic lymph node status (# nodes), IGF-1, C-peptide, IGFBP-3. Step-wise forward Cox multivariate models were used where a factor was added if p<=0.05, and interaction terms were added for TIMP-1 level and timing of chemotherapy. Results: High (categorical) TIMP-1 was significantly associated with longer RFS (p=0.04) in the non-bone RFS multivariate model in the subgroup of patients who had prior chemotherapy, but not in those who did not. The interaction between TIMP-1 and administration of chemotherapy before serum draw was significant (p=0.02). High (continuous) TIMP-1 was significantly associated with longer bone only RFS (p=0.04) in subgroup who had no chemotherapy before the serum draw, but not in those who may or may not have had it after. There was no significant interaction effect. Categorical and continuous TIMP-1 were not associated with any other type of RFS. Conclusions: We found a predictive benefit with the assessment of serum TIMP-1 in hormone receptor positive patients, that high TIMP-1 levels after adjuvant chemotherapy were predictive of a reduction in non-bone RFS.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3022.

Use of pretreatment serum CA9 (carbonic anhydrase 9) to predict PFS and survival in trastuzumab-treated metastatic breast cancer

11092

Background: Approximately half of HER2-positive breast cancer patients will respond to first-line trastuzumab-containing therapy. However, in those patients with an initial trastuzumab response, most will progress within a year with acquired resistance. Since trastuzumab treatment is also now used in the HER2-positive adjuvant breast cancer setting, trastuzumab resistance will continue to be a vexing clinical problem, and better predictive and prognostic biomarkers are urgently needed. Methods: Serum HER2, tissue inhibitor of metalloproteinase-1 (TIMP-1), urokinase-type plasminogen activator (uPA), CA9, VEGF-165, and endoglin were measured using ELISA assays in 66 metastatic breast cancer patients before starting first-line trastuzumab-containing therapy. The HER2, TIMP-1, uPA, CA9, and VEGF-165 ELISAs were from Oncogene Science/Siemens Healthcare Diagnostics, Cambridge, MA; and the endoglin ELISA was from R&D Systems, Minneapolis, MN. Progression-free (PFS) and overall survival (OS) were analyzed using the Kaplan-Meier method and Cox modeling with continuous pretreatment serum biomarker variables. Results: Pretreatment serum HER2 (p= 0.005), TIMP-1 (p< 0.0001), uPA (p= 0.006), endoglin (p= 0.008), and CA9 (p <0.0001) were all significant as univariate continuous biomarkers for predicting PFS to first-line trastuzumab-containing therapy, but VEGF was not. In multivariate analysis for PFS with all six biomarkers, only serum CA9 (p= 0.002) was a significant independent covariate. For OS, pretreatment serum HER2 (p= 0.018), TIMP-1 (p< 0.0001), uPA (p< 0.0001), endoglin (p= 0.002), and CA9 (p< 0.0001) were all significant as univariate continuous biomarkers for prognosis, but serum VEGF was not. In multivariate analysis for OS with all six biomarkers, only serum CA9 was a significant independent prognostic covariate (p= 0.001). Conclusions: Elevated pretreatment serum CA9 (a marker of hypoxia) predicts reduced progression-free survival and overall survival in metastatic breast cancer patients treated with first-line trastuzumab-containing therapy. These serum biomarkers deserve further study in larger trials of HER2-targeted breast cancer treatment. Supported by a grant from Komen for the Cure.

[Table: see text]

Pretreatment serum TIMP-1 levels and survival in advanced pancreatic cancer

e15568

Background: Tissue inhibitor of metalloproteinase-1 (TIMP-1) has been shown to have diverse multifunctional roles in tumorigenesis such as inhibition of the catalytic activity of MMPs, growth promotion, inhibition of apoptosis and regulation of angiogenesis. Elevated TIMP-1 has been associated with an unfavorable prognosis in many cancers including breast, colorectal, gastric, head and neck, lung, and lymphoma. VEGF is also intimately associated with angiogenesis. Methods: This study determined serum TIMP-1 and VEGF levels in a phase III clinical trial of 157 patients with advanced pancreatic cancer. ELISAs for TIMP-1 and VEGF (Oncogene Science / Siemens HealthCare Diagnostics, Cambridge, MA) were employed to measure pretreatment serum TIMP-1 levels in 157 pancreatic cancer patients enrolled in a randomized, double-blind, placebo-controlled phase III trial. Statistical analysis was performed with TIMP-1 and VEGF on a continuous and cutpoint basis. Serum biomarker levels were then correlated with patient survival using Kaplan -Meier life table analysis. Results: Serum TIMP-1 levels in 157 pancreatic patients had a median of 409.9 ng/mL, and ranged from 144 to 1078 ng/mL. Patients with higher serum TIMP-1 had significantly shorter survival on a continuous basis (p = 0.001), on quartile analysis (p = 0.004), and on a dichotomous cutpoint analysis of upper 25 % vs lower 75 % (median survival 101 days vs. 197 days)(p< 0.001). Serum VEGF level was not associated with survival on a continuous (p = 0.57) or cutpoint analysis (p= 0.93). Conclusions: Pancreatic cancer patients with higher serum TIMP-1 levels had significantly shorter overall survival. Serum TIMP-1 level should be evaluated as a predictive factor for response to novel treatment regimens.

[Table: see text]

Serum biomarker analysis in a phase II study of irinotecan in refractory metastatic breast cancer (MBC)

Abstract #6074

Objective: To analyze blood-serum biomarkers (HER2, EGFR, uPA, and TIMP-1) for prediction of response to treatment in conjunction with Study 96-32-55, a multicenter phase II trial assessing the efficacy and tolerability of two irinotecan schedules in anthracycline- or taxane-refractory MBC patients.&#x2028; Methods: MBC patients who experienced disease progression after one to three chemotherapy regimens, including at least one anthracycline- or taxane-based regimen, were randomly assigned to irinotecan in 6-week cycles comprising 100 mg/m2 weekly for 4 weeks, then a 2-week rest or 240 mg/m2 every 3 weeks. During this study the serum samples from each patient were collected at a possibility of three time points; prior to treatment, at the first occurrence of response, and at completion of or withdrawal from treatment. Response prediction was analyzed using predetermined elevated/non-elevated serum biomarker cutoffs. Percentage changes from baseline to first response and disease progression were analyzed.&#x2028; Results: In the weekly arm, the objective response (CR+PR) rate was 23% (95% CI, 13% to 37%), and in the every-3-weeks arm, the objective response rate was 14% (95% CI, 6% to 26%). Serum biomarker levels were determined for HER2, EGFR, uPA, and TIMP-1 prior to treatment for 91 patients. Of these 91 patients, 17 had serum measurements at first response, and 38 had serum measurements at their completion of study due to disease progression. Only 7 patients had serum-levels collected at all three event-points. The baseline levels of sHER2, EGFR, uPA, and TIMP-1 were not different among responders and non-responders (Fisher's Exact p=0.41, 0.26, 0.68, 0.75). sHER2 level increased by 20.6% from baseline to disease progression (p=0.01). TIMP-1 level was 15.2% lower than baseline at first response (p=0.03), 16.5% higher than baseline at disease progression (p=0.01), and for 7 patients with all three event-point measures, TIMP-1 was 21.8% lower than baseline at first response and was 22.3% higher than baseline at disease progression (p=0.02, 0.04).&#x2028; Conclusions: In this study, serum levels of HER2, EGFR, uPA, and TIMP-1 do not appear to be predictive of response. However, interpretation of the data is compromised due to limited availability of serum at all 3 points. Serum HER2 appears higher at disease progression than at baseline. Serum TIMP-1 appears to decrease from baseline to first response, and then appears to increase at disease progression.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6074.

Elevated plasma TIMP-1 levels predict reduced survival in metastatic hormone-refractory prostate cancer patients

5143

Background: Tissue inhibitor of metalloproteinase-1 (TIMP-1) has been shown to have parodoxical multifunctional roles in tumorigenesis: inhibition of the catalytic activity of MMPs, growth promotion, inhibition of apoptosis, and regulation of angiogenesis. Increased TIMP-1 has been associated with an unfavorable prognosis in many cancers including breast, colorectal, gastric, head and neck, lung cancer, and lymphomas. Methods: EDTA plasma TIMP-1 was determined from 60 hormone-refractory prostate cancer (HRCaP) patients using the TIMP-1 ELISA from Oncogene Science / Bayer HealthCare, Cambridge, MA. Patients were identified from an institutional database and had metastatic, HRCaP at the time of blood collection, which ranged from <1 month to 14 yrs. after the start of androgen-deprivation therapy (ADT); some patients had also received several chemotherapy regimens by the time of blood collection. Median follow-up was 17 mo. after blood collection and 27/60 patients had died. Overall survival was analyzed using Kaplan-Meier method and Cox modeling on tertiles of the TIMP-1 distribution. Results: The median EDTA plasma TIMP-1 level from the 60 HRCaP patients was 335 ng/ml (range 21 - 1391 ng/ml). Median survival since time of blood collection was 14 mo. Survival differed across TIMP-1 levels (P<0.01, logrank test), in particular the upper tertile of plasma TIMP-1 had a significantly reduced overall survival from the time of blood collection compared to the lowest tertile: A larger confirmatory study which will include a multivariate analysis of known prognostic factors is planned. Conclusions: Elevated plasma TIMP-1 tertile level predicted reduced survival in HRCaP patients. Soluble TIMP-1 deserves further study to determine its predictive and prognostic biomarker potential in a larger cohort of prostate cancer patients.

[Table: see text]

[Table: see text]

BCIRG 007: Serum HER2 levels in women with metastatic HER2-amplified breast cancer

1020

Background: BCIRG 007 is a multicenter, phase 3 randomized trial comparing docetaxel and trastuzumab (TH) with docetaxel, platinum salt (cisplatin or carboplatin) and trastuzumab (TCH) as first line chemotherapy in women with metastatic breast cancer (MBC). Women enrolled in the study had to have primary breast tumors with HER2 amplification as determined by centralized FISH analysis. Methods: We determined the percentage of subjects with HER2 amplification who had elevated (>15ng/mL) baseline levels of serum HER2 prior to the initiation of trastuzumab-based therapies. Baseline was considered to be the last available determination within 21 days prior to first treatment. Results: The median baseline serum HER2 levels was 75.8 ng/mL (range=8–3,280 ng/mL) for all subjects (n=123), with no statistical difference between subjects randomized to receive TH (median=65.9 ng/mL, n=64) and those randomized to receive TCH (median=89.9 ng/mL, n=59). Overall, 89% of the 123 subjects with HER2-amplified primary tumors had serum HER2 levels >15 ng/mL at the time of metastatic disease (86% in TH vs 92% in TCH). Conclusions: There was no statistical impact of baseline serum HER2 levels on any important clinical event: response to treatment, clinical benefit (response or stable disease for more than 24 weeks), disease progression or death. Conversely, when serum HER2 was measured over time, subjects with higher levels had an elevated risk of experiencing progressive disease (p=.003), even after adjustment for extent of disease (1 or 2 vs 3 or more organs involved) and presence of visceral disease. These analyses suggest that monitoring serum HER2 levels over the course of disease may be a means for detecting progressive disease in women with HER2 amplified breast cancer. Given the long intervals between the serum HER2 measurement and progression (up to 9 months), caution is required in interpreting these results.

No significant financial relationships to disclose.

Tissue expression and serum levels of the oncoprotein HER-2/neu in 157 primary breast tumours

BACKGROUND

We studied HER-2 expression in paired serum and tissue samples, in 157 selected cases from 701 consecutive primary breast cancer patients with pre-treatment HER-2 extracellular domain (ECD) > or = 10 ng/ml, or < 10 ng/ml but showing a HER-2 ECD lead time before first metastasis.

PATIENTS AND METHODS

HER-2 ECD was measured by the Immuno 1 automated ELISA (Bayer). Tumour tissue was analysed by immunohistochemistry (IHC) with Dako A 0485 and CB 11 antibodies and scored with the Dako scoring system.

RESULTS

Mean HER-2 ECD was 12.48+/-7.08 ng/ml and 21/157 (13.4%) sera were > or = 15 ng/ml (cut-off). Forty tumours (25.48%) showed both invasive and intraductal components, 3 (1.91%) were pure in situ carcinomas and 114 (72.61%) were pure invasive tumours. Elevated HER-2 ECD concentration was related only to pT (p=0.0008), histological grade (p=0.0465), presence of comedonecrosis (p=0.0123) or comedo-type carcinoma (p=0.041) and was unrelated to the presence of an intraductal component. HER-2 ECD was > or = 15 ng/ml in 48% of Dako 3+ and 60% of CB 11 2+ and 3+ tumours. By logistic regression analysis, the significant parameters associated with HER-2 ECD concentration were pT (p=0.0038) and Dako 3+ scores (p=0.0005). In Dako 3+ or CB 11 2+3+ tumours, elevated mean HER-2 ECD concentrations were observed only when pT exceeded 28-30 mm (p=0.0062 and p=0.0036, respectively).

CONCLUSION

In breast tumours, a threshold in size and HER-2 overexpression is necessary to observe elevated concentrations of HER-2 ECD at diagnosis. This information may be useful when the primary tumour is not available for IHC.

Serum HER-2/neu and response to the aromatase inhibitor letrozole versus tamoxifen

PURPOSE

To determine the effect of elevated serum HER-2/neu on the response of metastatic breast cancer patients to an aromatase inhibitor versus an antiestrogen.

PATIENTS AND METHODS

Five hundred sixty-two estrogen receptor-positive metastatic breast cancer patients were randomized to first-line hormone therapy with either letrozole or tamoxifen. An automated enzyme-linked immunosorbent assay was used to detect serum HER-2/neu.

RESULTS

For patients with normal serum HER-2/neu (70.5%), objective response rate (ORR; 39% in letrozole-treated patients v 26% in tamoxifen-treated patients; P =.008), clinical benefit (CB; 57% v 45%; P =.016), time to progression (TTP; median, 12.2 v 8.5 months; P =.0019), and time to treatment failure (TTF; median, 11.6 v 6.2 months; P =.0066) were significantly better in patients treated with letrozole. In the elevated HER-2/neu group (29.5%), there was no significant difference in ORR (17% in letrozole-treated patients v 13% in tamoxifen-treated patients; P =.45) or CB (33% v 26%; P =.31), but there was a strong trend in favor of a longer TTP with letrozole (median, 6.1 v 3.3 months; P =.0596) and a significantly longer TTF with letrozole (median, 6.0 v 3.2 months; P =.0418). Multivariate analysis revealed that elevated serum HER-2/neu was a negative predictor for ORR and TTP.

CONCLUSION

Patients with normal serum HER-2/neu receiving letrozole demonstrated a significantly greater ORR and CB and longer TTP and TTF than patients receiving tamoxifen. Although in patients with elevated serum HER-2/neu there was no significant difference between letrozole and tamoxifen in ORR or CB, there was a strong trend favoring longer TTP and significantly longer TTF with letrozole.

Elevated serum Her-2/neu level predicts decreased response to hormone therapy in metastatic breast cancer

PURPOSE

To determine the effect of elevation of serum HER-2/neu on response to hormone therapy.

PATIENTS AND METHODS

Seven hundred nineteen metastatic patients with estrogen receptor-positive (ER(+)), progesterone receptor-positive, or both or ER status unknown breast cancer were randomized in three independent clinical trials to receive second-line hormone therapy with either megestrol acetate or an aromatase inhibitor (fadrozole or letrozole). An automated enzyme-linked immunosorbent assay specific for the extracellular domain of the HER-2/neu (c-erbB-2) oncoprotein product was used to detect serum levels.

RESULTS

Two hundred nineteen patients (30%) had elevated serum HER-2/neu protein levels, using the mean + 2 SD (15 ng/mL) from the serum of healthy women as an upper limit. Response to treatment was available for 711 patients. The response rate (complete responses plus partial responses plus stable disease) to endocrine therapy was 45% in 494 patients with non-elevated and 23% in 217 patients with elevated serum HER-2/neu levels (P <.0001). Median duration of treatment response (using the time to progression [TTP] variable for patients who responded) was shorter in the group with elevated serum HER-2/neu levels (11.7 months) compared with the patient group with non-elevated levels (17.4 months). TTP, time to treatment failure, and median survival (17.2 months v 29.6 months) were also significantly shorter in the patients with elevated serum HER-2/neu levels (P <.0001).

CONCLUSION

Patients with ER(+) and serum HER-2/neu-positive metastatic breast cancer are less likely to respond to hormone treatment and have a shorter duration of response than ER(+) and serum HER-2/neu-negative patients. Their survival duration is also shorter.

Bcl-2 expression and DNA fragmentation in breast carcinoma, pathologic and steroid hormone receptors correlates

B-cell leukemia/lymphoma (bcl-2) expression can override the apoptosis development in lymphoid and hormonally regulated tissue-like breast. The presence of estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR) have revealed in breast carcinomas, but they have not been correlated to the bcl-2 protein expression and DNA fragmentation markers. We evaluated the immunohistochemical expression of bcl-2 protein and hormonal receptors (ER, PR, AR) and differentiation grade in 37 infiltrating ductal carcinomas of the breast for which frozen tissues were available for DNA extraction. The immunohistochemical reaction for bcl-2 was considered positive if more than 50% of neoplastic cells had intense cytoplasmic staining, whereas for steroid receptor evaluation Battifora's criteria were used. The DNA was extracted according to the phenol-chloroform procedure and used for bcl-2 gene rearrangement study of the major breakpoint region (Southern blot) and for membrane-based end-labeling using digoxigenin-labeled nucleotides and E. coli DNA polymerase I (Klenow fragment). The results were quantified by three different observers. Low-grade carcinomas were positive for bcl-2 protein (27/28, 96.4%) and ER (15/28, 53.6%), whereas the remaining neoplasms were negative for bcl-2 (9/9, 100.0%) and ER (8/9, 53.6%) (p < 0.001). No statistically significant differences were revealed at the bcl-2, PR and AR comparisons. The Southern blot analysis for bcl-2 major breakpoint region showed neither rearrangement nor genetic amplification (densitometric study). Only the membrane-based end-labeling of DNA fragments showed correlation with bcl-2 protein and ER expressions: all except one bcl-2-negative tumor and two bcl-2-positive tumors had positive labeling using 7 pg of DNA at dot blot analysis (p < 0.002). The bcl-2 protein expression would allow both proliferation and cell progression by blocking apoptosis in well-differentiated, ER-positive breast carcinomas. In these neoplasms, DNA fragmentation as a molecular marker of apoptosis was prevented by bcl-2 expression.

Prediction of response to antiestrogen therapy in advanced breast cancer patients by pretreatment circulating levels of extracellular domain of the HER-2/c-neu protein

PURPOSE

Overexpression of the HER-2/c-neu/c-erbB2 proto-oncogene is associated with a worse prognosis in patients with breast cancer, perhaps due to an association of the HER-2 proto-oncogene protein with resistance to hormone and/or chemotherapy. Circulating levels of the extracellular domain (ECD) of the HER-2/c-neu-related protein (NRP) are elevated in 20% to 40% of patients with metastatic breast cancer. We investigated whether pretreatment levels of NRP predict response to hormone therapy (HT).

MATERIALS AND METHODS

Circulating NRP levels were determined in 94 patients who participated in a randomized trial of three different doses of the antiestrogen, droloxifene (DRO), as first-line HT for metastatic breast cancer.

RESULTS

NRP levels were elevated (> or = 5,000 U/mL) in 32 of 94 patients (34%). Only three of 32 patients (9%) with elevated NRP levels responded to DRO, compared with 35 of 62 (56%) with nonelevated NRP levels (P = .00001). Low pretreatment NRP level was the most powerful predictor of response to DRO (odds ratio of response, 22.4; P = .0001). Elevated pretreatment NRP levels were also associated with a shorter time to progression (TTP) and survival duration.

CONCLUSION

Pretreatment circulating NRP levels predict a low likelihood of benefit from HT, specifically DRO, in patients with estrogen receptor (ER)-positive and/or progesterone receptor (PgR)-positive or receptor-unknown metastatic breast cancer, even when adjusted for other known predictive factors, such as ER and/or PgR levels, site of disease, disease-free interval from primary treatment to recurrence, and prior adjuvant chemotherapy. These data suggest that pretreatment NRP levels may be useful in deciding whether to treat a patient who otherwise appears to be likely to respond to HT.

Conformational effects in the p53 protein of mutations induced during chemical carcinogenesis: molecular dynamic and immunologic analyses

The tumor suppressor gene p53 has been identified as the most frequent target of genetic alterations in human cancers. Vinyl chloride, a known human carcinogen that induces the rare sentinel neoplasm angiosarcoma of the liver, has been associated with specific A-->T transversions at the first base of codons 249 and 255 of the p53 gene. These mutations result in an Arg-->Trp amino acid substitution at residue 249 and an Ile-->Phe amino acid substitution at residue 255 in a highly conserved region in the DNA-binding core domain of the p53 protein. To determine the effects of these substitutions on the three-dimensional structure of the p53 protein, we have performed molecular dynamics calculations on this core domain of the wild-type and the Trp-249 and Phe-255 mutants to compute the average structures of each of the three forms. Comparisons of the computed average structures show that both mutants differ substantially from the wild-type structure in certain common, discrete regions. One of these regions (residues 204-217) contains the epitope for the monoclonal antibody PAb240, which is concealed in the wild-type structure but accessible in both mutant structures. In order to confirm this conformational shift, tumor tissue and serum from vinyl chloride-exposed individuals with angiosarcomas of the liver were examined by immunohistochemistry and enzyme-linked immunosorbent assay. Individuals with tumors that contained the p53 mutations were found to have detectable mutant p53 protein in their tumor tissue and serum, whereas individuals with tumors without mutations and normal controls did not.

Serum oncoproteins in asbestosis patients

Using ELISAs, we determined the concentrations of transforming growth factor alpha (TGF-alpha), the extracellular domain of the erbB-2 receptor (erbB-2 ECD), and mutant p53 protein in stored serum samples of asbestosis patients with and without cancer and control subjects (without asbestosis or cancer). The percentage of individuals in these three groups with increased serum concentrations of TGF-alpha, erbB-2 ECD, and mutant p53, respectively, were: asbestosis patients with cancer, 36%, 16%, 19%; asbestosis patients without cancer, 38%, 19%, 6%; control subjects, 0%, 5%, 10%. Although differences in serum positivity for these oncoproteins were apparent among these groups, the differences did not achieve statistical significance (P > 0.05). In several of the cancer cases, increased concentrations of TGF-alpha, erbB-2 ECD, and mutant p53 were also detected in the stored serum samples collected years before the clinical diagnosis of disease.

Serum oncoproteins in asbestosis patients

Using ELISAs, we determined the concentrations of transforming growth factor alpha (TGF-alpha), the extracellular domain of the erbB-2 receptor (erbB-2 ECD), and mutant p53 protein in stored serum samples of asbestosis patients with and without cancer and control subjects (without asbestosis or cancer). The percentage of individuals in these three groups with increased serum concentrations of TGF-alpha, erbB-2 ECD, and mutant p53, respectively, were: asbestosis patients with cancer, 36%, 16%, 19%; asbestosis patients without cancer, 38%, 19%, 6%; control subjects, 0%, 5%, 10%. Although differences in serum positivity for these oncoproteins were apparent among these groups, the differences did not achieve statistical significance (P &gt; 0.05). In several of the cancer cases, increased concentrations of TGF-alpha, erbB-2 ECD, and mutant p53 were also detected in the stored serum samples collected years before the clinical diagnosis of disease.

Detection of serum p53 protein in lung cancer patients

Serum levels of p53 protein were examined in 23 cases of lung cancer (many with potential asbestos exposure), 23 unexposed matched hospital control subjects, 58 unmatched general population control subjects, and 4 people with nonmalignant lung disease using an enzyme-linked immunosorbent assay and Western immunoblotting. Average levels of serum p53 in the lung cancer patients (0.55 ng/mL) were higher than in the cases of nonmalignant lung disease (0.42 ng/mL) or in the matched (0.32 ng/mL) or unmatched (0.31 ng/mL) control subjects, but the differences were not statistically significant. However, three of the cases of lung cancer (13%) were found to have serum p53 levels much greater than those of the control subjects (> 2 SD above the mean) and to have confirmatory positive Western blots for p53. The tumors from these subjects demonstrated increased levels of p53 in the tissue by immunohistochemistry and/or the presence of mutations in the p53 gene. These results suggest that p53 protein can be detected in serum in a portion of lung cancer cases with p53 alterations in the tumor tissue.

The extracellular domain of p185/neu is released from the surface of human breast carcinoma cells, SK-BR-3

The human breast carcinoma cell line SK-BR-3, expresses the neu oncogene product, p185, which is a receptor tyrosine kinase. Using a double monoclonal antibody capture enzyme-linked immunosorbent assay for p185, activity was detected in conditioned media from cultures of SK-BR-3 cells. Two monoclonal antibodies specific for the extracellular domain of p185/neu immunoprecipitated a protein with a molecular mass of approximately 105 kDa. p105 was further shown to compete with p185 for binding to monoclonal antibodies and pulse-chase experiments indicate that it was generated by post-translational processing. Peptide maps showed that p105 and p185 are related polypeptides. Since p105 is close to the predicted size for the extracellular domain of p185/neu, we propose that SK-BR-3 cells specifically process and release this portion of the receptor into the medium. The release of the extracellular domain may have implications in oncogenesis and its detection could prove useful as a cancer diagnostic.

Distribution and immunochemical characterization of a keratin-like antigen in epithelial tumors using mouse and human monoclonal antibodies

Using conventional murine hybridoma technology, we have produced a monoclonal antibody (MAb), 89E5, which recognizes two keratin-like polypeptides (Mr 53,000 and 45,000), which are preferentially expressed by epithelial tumors. In addition to detection of tumor cells by immunohistochemistry, MAb 89E5 was able to localize to tumor xenografts in nude mice after iodination of its F(ab')2 fragments. To develop potentially less immunogenic antibodies to antigens defined by MAb 89E5, studies were performed to produce a human counterpart to the mouse MAb. The mouse 89E5 MAb was used to purify the 89E5 polypeptides from tumor cell lines. The partially purified 89E5 antigen was then used to sensitize human splenic lymphocytes in vitro. Immortalization of the sensitized cells by cell fusion resulted in a human IgM MAb, PA1, which showed the same reactivity pattern on a panel of cell lines as did the mouse MAb 89E5. Immunofluorescent studies showed that both 89E5 and PA1 had staining patterns on epithelial cells indicative of antibodies to cytokeratin. Furthermore, PA1 immunoprecipitated two polypeptides (Mr 53,000 and 45,000) which comigrated with the 89E5 polypeptides. Competitive binding assays showed that the PA1 MAb and 89E5 MAb recognized closely associated epitopes. As with the 89E5 MAb, PA1 was reactive with tumor tissues in immunohistochemical studies. These studies indicate that the PA1 MAb is a human counterpart of the mouse 89E5 MAb. Direct comparison of human MAb and mouse MAb against the same antigen could yield valuable information on the efficacy of using human MAb in vivo.

Virus-specific IgG and IgM antibodies in normal and immunocompromised subjects infected with cytomegalovirus

Levels of IgG and IgM antibodies t human cytomegalovirus (CMV) were measured using a solid-phase radioimmunoassay. Individuals positive by complement-fixation test consistently had detectable IgG titers by radioimmunoassay, but no quantitative relationship was apparent. An elevated IgM titer was considered specific for CMV infection because sera from individuals with other herpesvirus infections did not cross-react. In patients with mononucleosis, elevated titers of IgM antibody to CMV correlated (P less than 0.001) with active infection and were highest during viremia. Titers of IgG antibody to CMV during and after symptomatic infection were similar to those of asymptomatic positive individuals. Increases in CMV-specific IGM were observed in both primary and reactivated infections in cardiac transplant recipients. In a small group of cardiac transplant recipients with recurrent symptomatic disease, IgM titers were low at the time of viruria and did not increase with CMV tissue involvement, a result which suggests that quantitative deficiencies in IgM may be related to the severity of CMV infections.