Citations

Abstract Purpose: Advanced-stage epithelial ovarian cancer has a poor prognosis with long-term survival in less than 30% of patients. When the disease is detected in stage I, more than 90% of patients can be cured by conventional therapy. Screening for early-stage disease with individual serum tumor markers, such as CA125, is limited by the fact that no single marker is up-regulated and shed in adequate amounts by all ovarian cancers. Consequently, use of multiple markers in combination might detect a larger fraction of early-stage ovarian cancers. Experimental Design: To identify potential candidates for novel markers, we have used Affymetrix human genome arrays (U95 series) to analyze differences in gene expression of 41,441 known genes and expressed sequence tags between five pools of normal ovarian surface epithelial cells (OSE) and 42 epithelial ovarian cancers of different stages, grades, and histotypes. Recursive descent partition analysis (RDPA) was performed with 102 probe sets representing 86 genes that were up-regulated at least 3-fold in epithelial ovarian cancers when compared with normal OSE. In addition, a panel of 11 genes known to encode potential tumor markers [mucin 1, transmembrane (MUC1), mucin 16 (CA125), mesothelin, WAP four-disulfide core domain 2 (HE4), kallikrein 6, kallikrein 10, matrix metalloproteinase 2, prostasin, osteopontin, tetranectin, and inhibin] were similarly analyzed. Results: The 3-fold up-regulated genes were examined and four genes [Notch homologue 3 (NOTCH3), E2F transcription factor 3 (E2F3), GTPase activating protein (RACGAP1), and hematological and neurological expressed 1 (HN1)] distinguished all tumor samples from normal OSE. The 3-fold up-regulated genes were analyzed using RDPA, and the combination of elevated claudin 3 (CLDN3) and elevated vascular endothelial growth factor (VEGF) distinguished the cancers from normal OSE. The 11 known markers were analyzed using RDPA, and a combination of HE4, CA125, and MUC1 expression could distinguish tumor from normal specimens. Expression at the mRNA level in the candidate markers was examined via semiquantitative reverse transcription-PCR and was found to correlate well with the array data. Immunohistochemistry was performed to identify expression of the genes at the protein level in 158 ovarian cancers of different histotypes. A combination of CLDN3, CA125, and MUC1 stained 157 (99.4%) of 158 cancers, and all of the tumors were detected with a combination of CLDN3, CA125, MUC1, and VEGF. Conclusions: Our data are consistent with the possibility that a limited number of markers in combination might identify >99% of epithelial ovarian cancers despite the heterogeneity of the disease.

Abstract Purpose: We sought to test the hypothesis that the presence of telomerase activity in peritoneal washings of patients treated for ovarian carcinoma is a sensitive and specific indicator of the presence of residual disease. We hypothesized that this test, if added to second-look procedure protocols, could help determine whether residual disease is present or not in patients who have completed their adjuvant chemotherapy for ovarian carcinoma. Experimental Design: Peritoneal washings were obtained from 100 consecutive patients undergoing a second-look procedure after treatment for ovarian carcinoma (cases) and from 100 patients undergoing surgery for benign gynecological conditions (controls). The washings were assayed for telomerase activity using the telomerase repeat amplification protocol. The results were compared to the histological and cytological findings. Results: Among our 100 cases, 82 (82%) had either positive second-look procedures or expressed telomerase in their peritoneal washings. Fifty-three (53%) had positive second-look procedures, whereas 66 (66%) tested positive for telomerase. Twenty-nine of the 47 patients (62%) with negative second-look procedures tested positive for telomerase. Of the 53 patients with positive second-look procedures, 37 (70%) tested positive for telomerase. None of the 100 controls (0%) expressed telomerase in their peritoneal washings. Conclusions: Telomerase activity in peritoneal washings of patients treated for ovarian carcinoma and undergoing a second-look procedure may provide a means of increasing the sensitivity of such procedures for the detection of residual disease while maintaining a high level of specificity.

Abstract Purpose: The purpose of this research was to identify promiscuous T-helper cell determinants (THd) from carcinoembryonic antigen (CEA) to be used to prime T-cell help for cancer therapy. CEA was selected because this antigen is expressed in an important variety of carcinomas. Experimental Design: Potential promiscuous THd from CEA were predicted using available computer algorithms. Predicted peptides were synthesized and tested in binding experiments to different HLA-DR molecules. Binder peptides were then used to prime T-cell responses both in vitro and in vivo. Results: Twenty 15-mer peptides from CEA were predicted to bind to different HLA-DR molecules. The promiscuous character of these peptides was demonstrated in binding experiments. Fifteen of 20 peptides tested were able to bind to HLA-DR4, but only CEA (625–639) was shown to be presented after processing of recombinant CEA. CEA (625–639) was also found to be presented by HLA-DR53. Moreover, immunization of HLA-DR4 transgenic mice with CEA (625–639) in conjunction with class I epitope OVA (257–264), induced a CTL response specific of OVA (257–264). Conclusions: CEA (625–639) might be a relevant promiscuous THd peptide for cancer therapy.

Abstract Pyrazoloacridine (PZA) is an experimental antitumor agent presently under investigation for treatment of solid tumors on the basis of its unique mechanism of action and selectivity for human solid tumor xenograft in mice. Using capillary electrophoresis coupled with electrospray ionization mass spectrometry, we have identified three oxidative PZA metabolites, 9-desmethyl-PZA, N-demethyl-PZA, and PZA N-oxide. The cytochrome P450 (CYP) isoforms involved in PZA metabolism were characterized by studies with CYP chemical inhibitors, correlation of marker activities for selected CYPs with formation of the metabolites using a human liver panel, and PZA metabolism by cDNA-expressed CYPs. 9-Desmethyl-PZA formation was catalyzed by CYP1A2, whereas N-demethyl-PZA formation was catalyzed by CYP3A4. PZA N-oxide formation was catalyzed by flavin monooxygenase (FMO) rather than CYP, as determined by studies with chemical inhibitors of FMO and metabolism by cDNA-expressed human flavin monooxygenase. After administration of [10b-14C]PZA to mice, six urinary metabolites were detected by high-performance liquid chromatography UV and radiochromatograms including 9-desmethyl-PZA, N-demethyl-PZA, and PZA N-oxide. Trace concentrations of 9-desmethyl-PZA and PZA N-oxide were detected in mouse plasma. PZA N-oxide and N-demethyl-PZA were detected in urine from patients after PZA administration. PZA, 9-desmethyl-PZA, and PZA N-oxide inhibited growth of A375 human melanoma cells. IC50 values were 0.17, 0.11, and 7.0 μm, respectively, for the three molecules.

Abstract Purpose: Tumor markers ideally allow monitoring and prediction of disease progression. In Ewing’s sarcoma, a devastating childhood cancer, only a few reliable prognostic markers have been identified. To this end, we analyzed the expression of four tumor-promoting proteins, cyclin D1, HER2/Neu, Mdm2, and vascular endothelial growth factor (VEGF), in Ewing’s sarcoma. Experimental Design and Results: Thirty-one tissue samples from patients with Ewing’s sarcoma were stained with antibodies against cyclin D1, HER2/Neu, Mdm2, or VEGF. Whereas no significant expression of HER2/Neu and Mdm2 was detected, positive cyclin D1 and VEGF staining was observed in 42% and 55% of all tumors, respectively. Importantly, VEGF expression was found to be an independent negative predictor of survival in Ewing’s sarcoma patients, whereas cyclin D1 expression did not correlate with survival in these patients. Consistently, the Ewing’s sarcoma-specific EWS-ETS oncoproteins were capable of activating both the cyclin D1 and VEGF promoters in transient transfections of tissue culture cells. Furthermore, this activation was enhanced by coexpression of the Sp1 transcription factor. Using a mammalian two-hybrid system, some evidence was obtained that this may involve a physical interaction between EWS-ETS and Sp1 proteins. Conclusions: Our data reveal that VEGF may serve as a prognostic marker in Ewing’s sarcoma patients and provide a molecular mechanism by which VEGF and cyclin D1 expression is up-regulated in approximately half of all Ewing’s sarcomas.

Abstract The introduction of the nonsteroidal aromatase inhibitor (NS-AI) anastrozole as an alternative to tamoxifen for adjuvant therapy of women with resected hormone receptor-positive breast cancer has added a management category into which patients presenting with metastatic disease can be placed. There are now essentially three such categories: (a) tamoxifen sensitive (no prior AI); (b) tamoxifen resistant (no prior AI); and (c) NS-AI resistant (no prior tamoxifen). Well-conducted Phase III trials provide evidence for choosing first-line therapy for advanced disease in categories a and b. In tamoxifen-sensitive patients, one can choose either NS-AI, anastrozole, or letrozole. In tamoxifen-resistant patients, one can choose either of the NS-AIs, the steroidal AI exemestane, or the estrogen receptor down-regulator fulvestrant. The situation is quite different for patients in category c. There are no Phase III trials of agents in patients who have experienced disease progression on a NS-AI. Phase II data are available for exemestane and high-dose estrogens, and retrospective data are available for tamoxifen and fulvestrant. Additional clinical trials are needed to determine an optimal sequencing strategy.

Abstract Purpose: To assess the maximum tolerated dose, toxicities, pharmacokinetics, and antileukemic activity of topotecan and carboplatin in adults with recurrent or refractory acute leukemias. Experimental Design: Patients received topotecan and carboplatin by 5-day continuous infusion at nine dose levels. Patients achieving a complete remission received up to two additional courses for consolidation. Plasma topotecan and ultrafilterable platinum were assayed on days 1 to 5. In addition, pretreatment levels of various polypeptides in leukemic cells were examined by immunoblotting to assess possible correlations with response. Results: Fifty-one patients received a total of 69 courses of therapy. Dose-limiting toxicity consisted of grade 4/5 typhlitis and grade 3/4 mucositis after one course of therapy or grade 4 neutropenia and thrombocytopenia lasting >50 days when a second course was administered on day 21. Among 45 evaluable patients, there were 7 complete remissions, 2 partial remissions, 1 incomplete complete remission, and 1 reversion to chronic-phase chronic myelogenous leukemia. Topotecan steady-state plasma concentrations increased with dose. No accumulation of topotecan or ultrafilterable platinum occurred between days 1 and 5 of therapy. Leukemic cell levels of topoisomerase I, checkpoint kinase 1, checkpoint kinase 2, and Mcl-1 correlated with proliferating cell nuclear antigen but not with response. In contrast, low Bcl-2 expression correlated with response (P = 0.014, Mann-Whitney U test). Conclusions: The maximum tolerated dose was 1.6 mg/m2/d topotecan plus 150 mg/m2/d carboplatin. The complete remission rate in a heavily pretreated population was 16% (33% at the highest three dose levels). Responses seem to correlate with low pretreatment blast cell Bcl-2 expression.

Abstract Purpose: Most colorectal cancers that have high levels of microsatellite instability (MSI-H) show loss of immunohistochemical expression of proteins that participate in the DNA mismatch repair process, most often involving MLH1 and MSH2. Less commonly, a third DNA mismatch repair protein, MSH6, may also be lost as the primary event. Rarely, tumors with MSI-H show normal expression of these three proteins. The genetic deficiency leading to the MSI-H phenotype in such cases is unknown. PMS2 is another member of the DNA mismatch repair complex. Its expression is generally lost in tumors with MLH1 loss of expression. Rarely, there is selective loss of PMS2 expression. We sought to describe the frequency and clinical correlates of selective loss of expression of PMS2 with the MSI-H tumor phenotype. Experimental Design: Two thousand seven hundred nineteen colorectal cancers from both clinic- and research-based ascertainment were studied. Tumor MSI testing and immunohistochemistry for MLH1, MSH2, MSH6, and PMS2 were conducted. Medical records were abstracted for age at diagnosis, gender, colorectal cancer site, and family history. Results: Five hundred thirty-five of the 2,719 tumors were MSI-H. Of these, 93% showed loss of expression of MLH1, MSH2, and/or MSH6. Thirty-eight showed normal expression for these proteins. PMS2 immunohistochemical staining was successful in 32 of 38 of these tumors. Of the 32, 23 showed selective loss of expression of PMS2. This was associated with young age of diagnosis and right-sided location but not with a striking family history of cancer. Conclusions: Overall, 97% of the MSI-H tumors showed loss of expression for one or more of these four mismatch repair proteins. Selective loss of expression of PMS2 was present in 72% of cases in which colorectal cancers had an MSI-H phenotype but no alteration of expression of MLH1, MSH2, and MSH6. The underlying mechanism involved cannot be determined from this study but could involve point mutations in other DNA mismatch repair genes with retention of immunohistochemical expression, somatic inactivation of PMS2, or germ line mutation of PMS2.

Abstract Purpose: Epithelial ovarian cancers are thought to arise from flattened epithelial cells that cover the ovarian surface or that line inclusion cysts. During malignant transformation, different histotypes arise that resemble epithelial cells from normal fallopian tube, endometrium, and intestine. This study compares gene expression in serous, endometrioid, clear cell, and mucinous ovarian cancers with that in the normal tissues that they resemble. Experimental Design: Expression of 63,000 probe sets was measured in 50 ovarian cancers, in 5 pools of normal ovarian epithelial brushings, and in mucosal scrapings from 4 normal fallopian tube, 5 endometrium, and 4 colon specimens. Using rank-sum analysis, genes whose expressions best differentiated the ovarian cancer histotypes and normal ovarian epithelium were used to determine whether a correlation based on gene expression existed between ovarian cancer histotypes and the normal tissues they resemble. Results: When compared with normal ovarian epithelial brushings, alterations in serous tumors correlated with those in normal fallopian tube (P = 0.0042) but not in other normal tissues. Similarly, mucinous cancers correlated with those in normal colonic mucosa (P = 0.0003), and both endometrioid and clear cell histotypes correlated with changes in normal endometrium (P = 0.0172 and 0.0002, respectively). Mucinous cancers displayed the greatest number of alterations in gene expression when compared with normal ovarian epithelial cells. Conclusion: Studies at a molecular level show distinct expression profiles of different histologies of ovarian cancer and support the long-held belief that histotypes of ovarian cancers come to resemble normal fallopian tube, endometrial, and colonic epithelium. Several potential molecular markers for mucinous ovarian cancers have been identified.