Biomedical subjects
Publications and source records attributed to Kenneth R Hess.
This paper reviews some of the more salient recent developments in statistical aspects of clinical trial design methodology and suggests that more emphasis be placed on rigorous assessments of the new methodologies to place them in the context of existing methods, demonstrate their claimed advantages, and fully disclose their remaining limitations.
BACKGROUND: Laboratory and clinical data suggest that the anti-angiogenic agent, thalidomide, if combined with cytotoxic agents, may be effective against recurrent glioblastoma multiforme (GBM). OBJECTIVES: To determine 6-month progression-free survival (6PFS) and toxicity of temozolomide plus thalidomide in adults with recurrent GBM. PATIENTS AND METHODS: Eligible patients had recurrent GBM after surgery, radiotherapy, and/or adjuvant chemotherapy. Temozolomide was given at 150-200 mg/m(2)/day on days 1-5 of each 28-day cycle. Thalidomide was given orally at 400 mg at bedtime (days 1-28) and increased to 1,200 mg as tolerated. Patients were evaluated with magnetic resonance imaging scans every 56 days. The study was designed to detect an increase of the historical 6PFS for GBM from 10 to 30%. RESULTS: Forty-four patients were enrolled, 43 were evaluable for efficacy and safety. The study population included 15 women, 29 men; median age was 53 years (range 32-84); median Karnofsky performance status was 80% (range 60-100%). Thirty-six (82%) patients were chemotherapy-naïve. There were 57 reports of toxicity of grade 3 or greater. Non-fatal grade 3-4 granulocytopenia occurred in 15 patients (34%). The objective response rate was 7%. The estimated probability of being progression-free at 6 months with this therapy is 24% [95% confidence interval (C.I.) 12-38%]. The median time to progression is 15 weeks (95% C.I. 10-20 weeks). There was no observed correlation between serum levels of vascular endothelial growth factor, basic fibroblast growth factor, and IL-8 and the 6PFS outcome. CONCLUSION: This drug combination was reasonably safe, but with little indication of improvement compared to temozolomide alone.
The ability to site-specifically incorporate a diverse set of unnatural amino acids (>30) into proteins and quickly add new structures of interest has recently changed our approach to protein use and study. One important question yet unaddressed with unnatural amino acids (UAAs) is whether they can improve the activity of an enzyme beyond that available from the natural 20 amino acids. Herein, we report the >30-fold improvement of prodrug activator nitroreductase activity with an UAA over that of the native active site and a >2.3-fold improvement over the best possible natural amino acid. Because immense structural and electrostatic diversity at a single location can be sampled very quickly, UAAs can be implemented to improve enzyme active sites and tune a site to multiple substrates.
PURPOSE: To evaluate the cardiac safety of long-term trastuzumab therapy in patients with human epidermal growth receptor 2 (HER2) -overexpressing metastatic breast cancer (MBC) treated at The University of Texas M.D. Anderson Cancer Center (Houston, TX). PATIENTS AND METHODS: Among 218 MBC patients treated with trastuzumab-based therapy for at least 1 year, 173 patients were assessable for cardiac toxicity. Cardiac events (CEs) were defined as follows: asymptomatic decrease of left ventricular ejection fraction (LVEF) below 50%; decrease of 20 percentage points in LVEF compared with the baseline; or signs or symptoms of congestive heart failure (CHF). RESULTS: The median cumulative time for trastuzumab administration was 21.3 months. The median follow-up was 32.6 months (range, 11.8 to 79.0 months). Forty-nine patients (28%) experienced a CE: three patients (1.7%) had an asymptomatic decrease in the LVEF of 20 percentage points, 27 patients (15.6%) experienced grade 2 cardiac toxicity, and 19 patients (10.9%) experienced grade 3 cardiac toxicity. All but three patients had improved LVEF or symptoms of CHF with trastuzumab discontinuation and appropriate therapy. There was one cardiac-related death (0.5%). Baseline LVEF was significantly associated with CE (hazard ratio, 0.94; P = .001). The hazard of a CE among patients taking concomitant taxanes was higher early in the follow-up period but declined during the course of follow-up. CONCLUSION: The risk of cardiac toxicity of long-term trastuzumab-based therapy is acceptable in this population, and this toxicity is reversible in the majority of the patients. In patients who have experienced a CE, additional treatment with trastuzumab can be considered after recovery of cardiac function.
PURPOSE: We developed a multigene predictor of pathologic complete response (pCR) to preoperative weekly paclitaxel and fluorouracil-doxorubicin-cyclophosphamide (T/FAC) chemotherapy and assessed its predictive accuracy on independent cases. PATIENTS AND METHODS: One hundred thirty-three patients with stage I-III breast cancer were included. Pretreatment gene expression profiling was performed with oligonecleotide microarrays on fine-needle aspiration specimens. We developed predictors of pCR from 82 cases and assessed accuracy on 51 independent cases. RESULTS: Overall pCR rate was 26% in both cohorts. In the training set, 56 probes were identified as differentially expressed between pCR versus residual disease, at a false discovery rate of 1%. We examined the performance of 780 distinct classifiers (set of genes + prediction algorithm) in full cross-validation. Many predictors performed equally well. A nominally best 30-probe set Diagonal Linear Discriminant Analysis classifier was selected for independent validation. It showed significantly higher sensitivity (92% v 61%) than a clinical predictor including age, grade, and estrogen receptor status. The negative predictive value (96% v 86%) and area under the curve (0.877 v 0.811) were nominally better but not statistically significant. The combination of genomic and clinical information yielded a predictor not significantly different from the genomic predictor alone. In 31 samples, RNA was hybridized in replicate with resulting predictions that were 97% concordant. CONCLUSION: A 30-probe set pharmacogenomic predictor predicted pCR to T/FAC chemotherapy with high sensitivity and negative predictive value. This test correctly identified all but one of the patients who achieved pCR (12 of 13 patients) and all but one of those who were predicted to have residual disease had residual cancer (27 of 28 patients).
BACKGROUND: Conditionally replicating adenoviruses (CRAds) can be engineered to replicate selectively in cancer cells and cause cancer-specific cell lysis; thus they are considered a promising cancer therapy. METHODS: To elucidate the mechanisms by which CRAds induce cancer-specific cell death, we infected normal human fibroblasts (MRC5, telomerase negative), human malignant glioma (U373-MG and U87-MG), human cervical cancer (HeLa), and human prostate cancer (PC3) cells (all telomerase positive) with CRAds regulated by the human telomerase reverse transcriptase promoter (hTERT-Ad) or control nonreplicating adenoviruses (Ad-GFP). Nonapoptotic autophagy was assessed in Ad-GFP- and hTERT-Ad-infected cells by examining cell morphology, the development of acidic vesicular organelles, and the conversion of microtubule-associated protein 1 light chain 3 from the cytoplasmic form to the autophagosome membrane form; signaling via mammalian target of rapamycin (mTOR), an autophagy-associated molecule, was monitored by western blot analysis. We also compared the growth of subcutaneous gliomas in nude mice that were treated by intratumoral injection with Ad-GFP or hTERT-Ad. Survival of athymic mice carrying intracranial gliomas treated by intratumoral injection with Ad-GFP or hTERT-Ad was compared by using the Kaplan-Meier method and the Cox-Mantel log-rank analysis. All statistical tests were two-sided. RESULTS: hTERT-Ad induced tumor-specific autophagic cell death in tumor cells and in subcutaneous gliomas. hTERT-Ad-induced autophagy was associated with hTERT-Ad infection kinetics. The mTOR signaling pathway was suppressed in tumor cells and in subcutaneous gliomas treated with hTERT-Ad compared with GFP-Ad or no treatment as shown by reduced phosphorylation of mTOR's downstream target p70S6 kinase (p70S6K). hTERT-Ad treatment of mice (n = 7) slowed growth of subcutaneous gliomas (mean tumor volume = 39 mm3, 95% confidence interval [CI] = 23 to 54 mm3) compared with GFP-Ad treatment (n = 7) (mean tumor volume = 200 mm3, 95% CI = 149 to 251 mm3) at day 7 (volume difference = 161 mm3, 95% CI = 126 to 197 mm3; P < .001). Mice carrying intracranial tumors that were treated with three intratumoral injections of hTERT-Ad survived longer (53 days) than after treatment with GFP-Ad (29 days) (seven mice per group, difference = 24 days, 95% CI = 20 to 28 days; P < .001). CONCLUSIONS: hTERT-Ad may kill telomerase-positive cancer cells by inducing autophagic cell death.
PURPOSE: Since anaplastic gliomas (AG) depend on matrix metalloproteinases for tumor cell invasion and angiogenesis, we undertook this phase II study to evaluate the matrix metalloproteinase inhibitor marimastat (MT), combined with the alkylator temozolomide (TMZ) in patients with recurrent AG, looking for improved outcomes. PATIENTS AND METHODS: Patients were treated every 28 days with TMZ at 150-200 mg/m2 once daily on days 1-5 and MT at 25 mg twice daily on days 8-28. Results were compared to our database of anaplastic glioma patients treated at recurrence. A subanalysis of the relationship between MT-induced joint-related toxicity and anticonvulsant status was carried out. RESULTS: Forty-nine patients were enrolled; all were assessable for toxicity, and 46 were included in the efficacy analysis. Joint and muscle complaints occurred in 32 patients (65%); 1 patient was removed from the study due to toxicity. The best protocol response was a complete response in 1 patient and a partial response in 2 patients (3/46=7%, 95% confidence interval (CI)=1, 18). Median time to progression was 24 weeks (95% CI=16, 56), and the progression-free survival (PFS) rate was 48% at 6 months (95% CI=35%, 65%), which surpassed the protocol objective of 40%. Sub-analysis showed a positive impact of joint-related toxicity due to MT on PFS whether or not patients were taking CYP450 enzyme-inducing anticonvulsants. CONCLUSIONS: Even though this regimen is more efficacious than our comparator of historical controls in recurrent AG, the regimen was roughly equivalent to single-agent TMZ and was associated with additional toxicity. The sub-analysis suggests pharmacokinetic and drug-drug interactions which may positively impact responses to MT.
BACKGROUND: Unique metastatic patterns cited in the literature often arise from anecdotal clinical observations and autopsy reports. The authors analyzed clinical data from a large number of patients with histologically confirmed, distant-stage adenocarcinoma to evaluate metastatic patterns. METHODS: Tumor registry data were collected between 1994-1996 on 11 primary tumor sites and 15 metastatic sites from 4399 patients. The primary and metastatic sites were cross-tabulated in various ways to identify patterns, and the authors developed algorithms by using multinomial logistic regression analysis to predict the locations of primary tumors based on metastatic patterns. RESULTS: Three primary tumors had single, dominant metastatic sites: ovary to abdominal cavity (91%), prostate to bone (90%), and pancreas to liver (85%). The liver was the dominant metastatic site for gastrointestinal (GI) primary tumors (71% of patients), whereas bone and lung metastases were noted most frequently in non-GI primary tumors (43% and 29%, respectively). In a study of combinations of liver, abdominal cavity, and bone metastases, 86% of prostate primary tumors had only bone metastases, 80% of ovarian primary tumors had only abdominal cavity metastases, and 74% of pancreas primary tumors had only liver metastases. A single organ was the dominant source of metastases in 7 sites: axillary lymph node from the breast (97%), intestinal lymph node from the colon (84%), thoracic lymph node from the lung (66%), brain from the lung (64%), mediastinal lymph node from the lung (62%), supraclavicular lymph node from the breast (51%), and adrenal gland from the lung (51%). CONCLUSIONS: The algorithms that the authors developed achieved a cross-validated accuracy of 64% and an accuracy of 64% on an 1851-patient independent test set, compared with 9% accuracy when a random classifier was used.
PURPOSE: Glioblastoma multiforme (GBM) is the most common and aggressive glioma with the poorest survival. Use of biomarkers for screening patients with GBM may be used to modify treatments and improve outcomes. The level of human telomerase (hTERT) expression is an independent predictor of outcome of many cancers, and a functional variant of hTERT MNS16A (shorter tandem repeats or short [S] allele) is associated with increased hTERT mRNA expression. We investigated whether hTERT MNS16A variant genotype predicted survival in GBM patients. PATIENTS AND METHODS: We genotyped hTERT MNS16A in 299 GBM patients using polymerase chain reaction and determined hTERT genotype by classifying the DNA band of 243 or 272 base pairs (bp) as S allele and 302 or 333 bp as long (L) allele. We compared overall survival using Kaplan-Meier estimates and equality of survival distributions using the log-rank test, and we computed univariate and multivariate Cox proportional hazards models to estimate the effects of selected variables. RESULTS: Overall survival differed significantly by hTERT MNS16A genotype, with median survivals of 25.1, 14.7, and 14.6 months for the SS, SL, and LL genotypes, respectively. Compared with the SS genotype, the hazard ratios for the SL and LL genotypes were 1.69 and 1.87, respectively, after adjustment for other factors. Multivariate Cox regression analysis showed an independent statistically significant association between the hTERT MNS16A variant genotype and outcome. CONCLUSION: A functional hTERT MNS16A genotype is a potential biomarker for assessment of survival outcome of GBM. Larger studies are needed to verify these findings.
PURPOSE: The goals of this analysis were to (a) determine concordance of gene expression results from replicate experiments, (b) examine prediction agreement of multigene predictors on replicate data, and (c) assess the robustness of prediction results in the face of noise. PATIENTS AND METHODS: Affymetrix U133A gene chips were used for gene expression profiling of 97 fine-needle aspiration biopsies from breast cancer. Thirty-five cases were profiled in replicates: 17 within the same laboratory, 11 in two different laboratories, and 15 to assess manual and robotic labeling. We used data from 62 cases to develop 111 distinct pharmacogenomic predictors of response to therapy. These were tested on cases profiled in duplicates to determine prediction agreement and accuracy. To evaluate the robustness of the pharmacogenomic predictors, we also introduced random noise into the informative genes in one half of the replicates. RESULTS: The average concordance correlation coefficient was 0.978 (range, 0.96-0.99) for intralaboratory replicates, 0.962 (range, 0.94-0.98) for between-laboratory replicates, and 0.971 (range, 0.93-0.99) for manual versus robotic labeling. The mean % prediction agreement on replicate data was 97% (95% CI, 0.96-0.98; SD, 0.006), 92% (95% CI, 0.90-0.93; SD, 0.009), and 94% (95% CI, 0.92-0.95; SD, 0.008) for support vector machines, diagonal linear discriminant analysis, and k-nearest neighbor prediction methods, respectively. Mean accuracy in the test set was 77% (95% CI, 0.74-0.79; SD, 0.014), 66% (95% CI, 0.63-0.73; SD, 0.015), and 64% (95% CI, 0.60-0.67; SD, 0.016), respectively. CONCLUSION: Gene expression results obtained with Affymetrix U133A chips are highly reproducible within and across two high-volume laboratories. Pharmacogenomic predictions yielded >90% agreement in replicate data.
PURPOSE: Our goal was to determine whether single nucleotide polymorphisms (SNPs) in DNA repair genes influence the clinical outcome of pancreatic cancer. PATIENTS AND METHODS: We evaluated 13 SNPs of eight DNA damage response and repair genes in 92 patients with potentially resectable pancreatic adenocarcinoma. All patients were treated with neoadjuvant concurrent gemcitabine and radiotherapy with or without a component of induction gemcitabine/cisplatin at The University of Texas M.D. Anderson Cancer Center (Houston, TX) from February 1999 to August 2004 and observed through August 2005. Response to the pretreatment was assessed by evaluating time to tumor progression and overall survival. Kaplan-Meier plot, log-rank test, and Cox regression were used to compare survival of patients according to genotype. RESULTS: The RecQ1 A159C, RAD54L C157T, XRCC1 R194W, and ATM T77C genotypes had a significant effect on the overall survival with log-rank P values of .001, .004, .001, and .02, respectively. A strong combined effect of the four genotypes was observed. Patients with none of the adverse genotypes had a mean survival time of 62.1 months, and those with one, two, or three or more at-risk alleles had median survival times of 27.5, 14.4, and 9.9 months, respectively (log-rank P < .001). There is a significant interaction between the RecQ1 gene and other genotypes. All four genes except XRCC1 remained as independent predictors of survival in multivariate Cox regression models adjusted for other clinical predictors. CONCLUSION: These observations support the hypothesis that polymorphic variants of DNA repair genes affect clinical prognosis of patients with pancreatic cancer.
This study explored the use of complementary and alternative medicine (CAM) approaches and their relationship with demographic and disease characteristics and quality of life (QOL) in the primary brain tumor (PBT) population. One hundred one PBT patients were enrolled in this study. The results showed that 34% of patients reported using CAM. Forty-one percent reported using more than one type of CAM. The average cost of each CAM used per month was 69 dollars, with 20% of patients spending more than 100 dollars per month. The majority (74%) reported that their physicians were unaware of their use of CAM. Data analysis found a higher performance status to be the only factor significantly related to use of CAM therapy (P < 0.005). There was no difference in patient report of QOL between users and nonusers of CAM therapies. The high number of patients who do not report CAM use has potential implications for evaluation of symptoms and response to therapy in this population. This may be especially relevant in those patients with higher functional status participating in clinical trials.
PURPOSE: To combine clinical variables associated with pathologic complete response (pCR) and distant metastasis-free survival (DMFS) after preoperative chemotherapy (PC) into a prediction nomogram. PATIENTS AND METHODS: Data from 496 patients treated with anthracycline PC at the Institut Gustave Roussy were used to develop and calibrate a nomogram for pCR based on multivariate logistic regression. This nomogram was tested on two independent cohorts of patients treated at the M.D. Anderson Cancer Center. The first cohort (n = 337) received anthracycline; the second cohort (n = 237) received a combination of paclitaxel and anthracycline PC. A separate nomogram to predict DMFS was developed using Cox proportional hazards regression model. RESULTS: The pCR nomogram based on clinical stage, estrogen receptor status, histologic grade, and number of preoperative chemotherapy cycles had good discrimination and calibration in the training and the anthracycline-treated validation sets (concordance indices, 0.77, 0.79). In the paclitaxel plus anthracycline group, when the predicted pCR rate was less than 14%, the observed rate was 7.5%; for a predicted rate of > or = 38%, the actual rate was 85%. For a predicted rate between 14% to 38%, the observed rates were 50% with weekly and 27% with 3-weekly paclitaxel. This indicates that patients with intermediate chemotherapy sensitivity benefit the most from the optimized schedule of paclitaxel. Patients unlikely to achieve pCR to anthracylines remain at low probability for pCR, even after inclusion of paclitaxel. The nomogram for DMFS had a concordance index of 0.72 in the validation set and outperformed other prediction tools (P = .02). CONCLUSION: Our nomograms predict pCR accurately and can serve as a basis to integrate future molecular markers into a clinical prediction model.
PURPOSE: Molecular classification of breast cancer has been proposed based on gene expression profiles of human tumors. Luminal, basal-like, normal-like, and erbB2+ subgroups were identified and were shown to have different prognoses. The goal of this research was to determine if these different molecular subtypes of breast cancer also respond differently to preoperative chemotherapy. EXPERIMENTAL DESIGN: Fine needle aspirations of 82 breast cancers were obtained before starting preoperative paclitaxel followed by 5-fluorouracil, doxorubicin, and cyclophosphamide chemotherapy. Gene expression profiling was done with Affymetrix U133A microarrays and the previously reported "breast intrinsic" gene set was used for hierarchical clustering and multidimensional scaling to assign molecular class. RESULTS: The basal-like and erbB2+ subgroups were associated with the highest rates of pathologic complete response (CR), 45% [95% confidence interval (95% CI), 24-68] and 45% (95% CI, 23-68), respectively, whereas the luminal tumors had a pathologic CR rate of 6% (95% CI, 1-21). No pathologic CR was observed among the normal-like cancers (95% CI, 0-31). Molecular class was not independent of conventional cliniocopathologic predictors of response such as estrogen receptor status and nuclear grade. None of the 61 genes associated with pathologic CR in the basal-like group were associated with pathologic CR in the erbB2+ group, suggesting that the molecular mechanisms of chemotherapy sensitivity may vary between these two estrogen receptor-negative subtypes. CONCLUSIONS: The basal-like and erbB2+ subtypes of breast cancer are more sensitive to paclitaxel- and doxorubicin-containing preoperative chemotherapy than the luminal and normal-like cancers.
BACKGROUND: Pancreatic carcinoma exhibits a unique genetic profile of mutations that may play key roles in its progression to malignant phenotypes. Constitutive activation of transcription factor nuclear factor kappa B (NF-kappaB) is a frequent molecular alteration in pancreatic carcinoma, suggesting a possible link between inflammation and cancer. The aims of the current study were to determine the effects of aspirin on pancreatic carcinoma prevention and to reveal a possible mechanism of aspirin-mediated cancer chemoprevention. METHODS: An orthotopic mouse model with human pancreatic carcinoma cell lines PANC-1, PANC-1/Puro, and PANC-1/IkappaBalphaM was used to study the inhibitory effects of aspirin on pancreatic tumor formation. RESULTS: Aspirin inhibited constitutive NF-kappaB activity in culture and, in turn, decreased the expression of the NF-kappaB downstream target gene, Cox-2, in PANC-1 or PANC-1/Puro cells, without significantly inhibiting the in vitro growth of PANC-1/Puro cells. All animals inoculated with either PANC-1 or PANC-1/Puro cells, and not given aspirin, developed pancreatic tumors, whereas none of the mice injected with PANC-1/IkappaBalphaM cells showed any evidence of pancreatic tumor formation. Animals given aspirin for 6 days before, or at the time of, orthotopic tumor cell injection showed a significantly lower incidence of tumor formation compared with those receiving aspirin 2 weeks after inoculation and controls receiving no aspirin. CONCLUSIONS: Aspirin repressed tumor formation by PANC-1 cells in vivo in a prophylactic setting, suggesting a possible mechanism for aspirin's preventive effect in pancreatic carcinoma through inhibition of NF-kappaB activation and a mechanistic link between inflammation and tumorigenesis. Aspirin-mediated antiinflammatory approaches might be an effective strategy to prevent pancreatic carcinoma.
Breast cancers show variable sensitivity to paclitaxel. There is no diagnostic test to identify tumors that are sensitive to this drug. We used U133A chips to identify genes that are associated with pathologic complete response (pCR) to preoperative paclitaxel-containing chemotherapy in stage I-III breast cancer (n = 82). Tau was the most differentially expressed gene. Tumors with pCR had significantly lower (P < 0.3 x 10(-5)) mRNA expression. Tissue arrays from 122 independent but similarly treated patients were used for validation by immunohistochemistry. Seventy-four percent of pCR cases were tau protein negative; the odds ratio for pCR was 3.7 (95% confidence interval, 1.6-8.6; P = 0.0013). In multivariate analysis, nuclear grade (P < 0.01), age <50 (P = 0.03), and tau-negative status (P = 0.04) were independent predictors of pCR. Small interfering RNA experiments were performed to examine whether down-regulation of tau increases sensitivity to chemotherapy in vitro. Down-regulation of tau increased sensitivity of breast cancer cells to paclitaxel but not to epirubicin. Tubulin polymerization assay was used to assess whether tau modulates binding of paclitaxel to tubulin. Preincubation of tubulin with tau resulted in decreased paclitaxel binding and reduced paclitaxel-induced microtubule polymerization. These data suggest that low tau expression renders microtubules more vulnerable to paclitaxel and makes breast cancer cells hypersensitive to this drug. Low tau expression may be used as a marker to select patients for paclitaxel therapy. Inhibition of tau function might be exploited as a therapeutic strategy to increase sensitivity to paclitaxel.
PURPOSE: To determine the clinicopathologic behavior of gastric adenocarcinoma in Hispanics by comparing Hispanic and non-Hispanic patients treated at a single cancer center. PATIENTS AND METHODS: Medical records of patients with invasive gastric cancer treated from 1985 to 1999 were reviewed. Diagnoses were pathologically confirmed. Differences in categorical variables were assessed using the chi(2) test. Logistic regression was used for multivariate analyses. Median survival was estimated using the Kaplan-Meier method. Cox proportional hazards modeling was used to assess the impact of covariates. RESULTS: Of 1,897 patients, 301 (15.9%) were Hispanic. Hispanics were significantly younger at diagnosis than non-Hispanic whites (53.1 +/- 14.4 years v 59.4 +/- 12.7 years, respectively; P < .005) or African Americans (57.6 +/- 15.3 years, P < .005). Hispanics were less likely to have proximal gastric cancers compared with whites (38.9% v 59.5%, respectively; P < .005). Hispanics were more likely to have mucinous/signet-ring type histology (42.5%) than whites (27.4%) and African Americans (32.5%; P < .005). Hispanics were more likely to require total gastrectomy (51%) compared with whites (38%), African Americans (38%), and Asians (36%; P = .039). Among patients with metastases at diagnosis, Hispanics were less likely to have liver metastasis than whites (30% v 44%, respectively; P = .009) but more likely to have peritoneal metastasis than whites and African Americans (54% v 41% and 47%, respectively; P = .002). In Cox analyses, Asian race, earlier stage, papillary/tubular histology, distal location, and younger age were favorable predictors of survival. CONCLUSION: Hispanic ethnicity does not impact survival in gastric adenocarcinoma. However, histology, metastasis pattern, tumor localization, and other clinical parameters differ sufficiently to warrant further investigation into the epidemiology, pathogenesis, and molecular biology of gastric cancer in this population.
PURPOSE: Pancreatic adenocarcinoma is currently the fourth leading cause of cancer death in the United States, and most pancreatic cancers develop locally advanced disease or metastasis at the time of diagnosis. The mechanisms by which it invades and metastasizes are not known. EXPERIMENTAL DESIGN: To identify the genes involved in pancreatic cancer metastasis, we analyzed the gene expression profiles between highly metastatic Colo357L3.6pl and parental Colo357FG pancreatic cancer cell lines using cDNA microarrays and confirmed differential gene expression by reverse transcription-PCR, Western blotting, and immunologic analysis of 54 samples from pancreatic cancer patients. The correlation with clinical outcome was also examined. The possible signaling pathways involved with tropomyosin-related kinase B (TrkB) were analyzed. RESULTS: Our findings showed that TrkB was overexpressed in the highly metastatic Colo357L3.6pl cells, which correlated with perineural invasion (P = 0.026), positive retroperitoneal margin (P = 0.0005), and shorter latency to development of liver metastasis (Cox proportional hazard ratio, 0.3; 95% confidence interval, 0.1-0.8; P = 0.01) in patient samples. Extracellular signal-regulated kinases 1 and 2 were activated and Elk-1 and AP-1 DNA binding activity was induced in Colo357L3.6pl cells. Furthermore, interleukin 8 and vascular endothelial growth factor were more strongly expressed in Colo357L3.6pl than Colo357FG cells, and these findings were confirmed in Colo357L3.6pl and Colo357FG orthotopic tumors. CONCLUSION: These results suggest that overexpression of TrkB and activation of mitogen-activated protein kinase and AP-1, which may in turn induce the expression of vascular endothelial growth factor and interleukin 8, may mediate the cardinal clinical features of locally aggressive growth and metastasis of pancreatic cancer. Our results also imply that TrkB receptor may be a novel therapeutic target for pancreatic cancer.