Methylation profiling of rectal cancer identifies novel markers of early-stage disease

BACKGROUND

Radical surgery is the de facto treatment for early rectal cancer. Conservative surgery with transanal endoscopic microsurgery can achieve high rates of cure but the histopathological measures of outcome used to select local treatment lack precision. Biomarkers associated with disease progression, particularly mesorectal nodal metastasis, are urgently required. The aim was to compare patterns of gene-specific hypermethylation in radically excised rectal cancers with histopathological stage.

METHODS

Locus-specific hypermethylation of 24 tumour suppressor genes was measured in 105 rectal specimens (51 radically excised adenocarcinomas, 35 tissues adjacent to tumour and 19 normal controls) using the methylation-specific multiplex ligation-dependent probe assay (MS-MLPA). Methylation values were correlated with histopathological indices of disease progression and validated using bisulphite pyrosequencing.

RESULTS

Five sites (ESR1, CDH13, CHFR, APC and RARB) were significantly hypermethylated in cancer compared with adjacent tissue and normal controls (P < 0·050). Methylation at these sites was higher in Dukes' A than Dukes' 'D' cancers (P = 0·013). Methylation at two sites (GSTP1 and RARB) was individually associated with localized disease (N0 and M0 respectively; P = 0·006 and P = 0·008). Hypermethylation of at least two of APC, RARB, TIMP3, CASP8 and GSTP1 was associated with early (N0 M0) disease (N0, P = 0·002; M0, P = 0·044). Methylation levels detected by MS-MLPA and pyrosequencing were concordant.

CONCLUSION

Locus-specific hypermethylation was more prevalent in early- than late-stage disease. Hypermethylation of two or more of a panel of five tumour suppressor genes was associated with localized disease.

Clinicopathologic and genetic features of Chinese hereditary nonpolyposis colorectal cancer (HNPCC)

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Background: Hereditary non-polyposis colorectal cancer (HNPCC) is the most common hereditary colorectal cancer (CRC). At least five mismatch repair genes, majorly hMLH1and hMSH2 gene mutations, are associated with this syndrome. Given the geographical and racial differences, Chinese HNPCC patients have some special characteristics compared with patients in West countries. Based on our former studies, we developed a criteria, the Fudan Criteria, for clinical diagnosis of Chinese HNPCC. The aim of this study is (1) to understand the relationship between genotype and phenotype in Chinese HNPCC; and (2) to investigate the clinical value of Fudan Criteria.

Methods: 116 unrelated probands of HNPCC or suspected HNPCC families from the Fudan Colorectal Registry were studied. 32 families fulfilled the Amsterdam criteria (AC group), 28 families fulfilled the Fudan Criteria (FD group). 56 families met the revised Bethesda guideline (BG Group). Direct DNA sequencing of all exons of hMSH2 and hMLH1 genes were performed. Mutation and clinicalpathological features were compared between the groups.

Results: 32 pathological germline mutations were identified. 16/32 mutations were located at hMLH1 and 16/32 located at hMSH2. The sensitivity of Amsterdam Criteria was 50%, specificity was 81% and Youden's index was 31%. The sensitivity of Fudan Criteria was 75%, specificity was 58% and Youden's index was 33%. In AC group, there were no significant clinicopathological differences in patients with or without mutation. However, families with hMSH2 mutation had a higher ratio of synchronous and metachronous CRC than families with hMLH1 mutation (33% vs. 6%; P=0.04). Families in AC group share the same clinicopathological features with families in FD group, except multiple relative tumors (21.6% vs.6%; P=0.001).

Conclusions: There seems no close relation between genotype and phenotype, except patients with hMSH2 mutation more frequently harbor synchronous and metachronous CRC. Fudan Criteria had a little higher sensitivity and accuracy than Amsterdam Criteria for identification of Chinese HNPCC.

No significant financial relationships to disclose.

Abstract P3-05-01: “VISA” Nanopaticles to Breast Cancer In Vitro and in Living Imaging Animal Models

Development of cancer gene therapy has been hampered by the fact that there are no effective cancer-specific expression vectors available, which is critical for improving therapeutic efficacy and reducing toxicity in clinics. To overcome this problem, we recently developed a safe and effective strategy fro targeting a potent pro-apoptotic gene (BikDD) to the pancreatic tumors (Xie et al. Cancer Cell, 2007), lung cancer (Sher et al. Oncogene, 2009) and ovarian cancer (Xie et al. Molecular Cancer Therapeutics, 2009). A VISA system (VP16-Gal4-WPRE integrated systemic amplifier) was engineered by using the two-step transcriptional amplification (TSTA) system and the posttranscriptional regulatory element of the woodchuck hepatitis virus (WPRE). The VISA system can boost the activity of cancer-specific promoters by an average of 600-800-folds compared to their basal levels. C-VISA (CCKAR-VISA) nanoparticles transcriptionally targets transgene expression effectively to pancreatic tumors in vivo. C-VISA-BikDD nanoparticles was shown to be highly effective in reducing tumor burden and increasing animal survival rate in orthotopic pancreatic cancer models which is moving into clinical trials at University of Texas M.D. Anderson Cancer Center, USA. In the current study, we identified hTERT(human telomerase reverse transcriptase), survivin, β-cateinin, claudin-4, and FASN (fatty acid synthase) promoters as breast cancer-selective promoters, and amplified their activity to hundreds of folds greater by the “VISA” system(called x-VISA) without loss of their specificity. Very importantly, the x-VISA promoters were also robust in the primary cultured breast cancer cells, with 42.5 %-65% of the CMV promoter, while retaining stringent pancreatic cancer specificity. x-VISA was also shown to target expression of firefly luciferase to MDA-MB-468 xenografts in an orthotopic mouse model, confirmed by noninvasive imaging with an Xenogen IVIS™ imaging system and measuring with a luminometer. The cancer-specific index was 35-60 for x-VISA-Luc and 0.01 for CMV-Luc in vivo. We further demonstrated significant antitumor activity of targeted BikDD expression driven by nanoparticles of the hTERT-VISA-BikDD vectors in Her-2-negative and-positive and triple-negative breast cancer cell lines in vitro, and in multiple breast cancer models of living imaging by the Xenogen IVIS imaging system with limited toxicity. In addition, treatment with hTERT-VISA-BikDD nanoparticles plus lapatinib or produces evident combinational therapeutic efficacy, which is likely due to the ability of lapatinib to promote apoptosis of Her-2-overexpressing breast cancer cells. Thus, our newly developed hTERT-VISA-BikDD nanoparticles are an innovative strategy for targeted antitumor effects of Her-2-negative, Her-2-positive and triple-negative breast cancer.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-05-01.

Abstract P1-09-08: Survival, Health Care Cost and Utilization of Patients with Triple Negative Breast Cancer in a U.S. Managed Care Setting

Objectives: Triple negative breast cancer (TNBC), a subtype of breast cancer characterized by its unique molecular profile and aggressive clinical behavior, lacks satisfactory standard therapies. Little is known about survival and economic cost of patients with TNBC. This study was conducted to compare the survival, health care cost and utilization of patients with TNBC versus patients with breast cancer that is not triple negative.

Methods: Analyses were conducted using Impact Intelligence Oncology Management (IIOM) (2002-2009) linked with United Health administrative claims. Patients were followed from the time of initial breast cancer diagnosis until death, disenrollment or end of the observation period. Continuous enrollment was required during the observation period. Staging and estrogen and progesterone receptors (ER/PR) and HER2 status were obtained at time of initial diagnosis. Patients’ age, region, cancer stage, comorbid conditions, health care costs and utilization prior to the initial diagnosis were controlled for risk-adjusted comparison. Cox regression was used for survival analysis. Health care resource use during the follow-up after initial diagnosis, such as number of hospitalizations, emergency room (ER) visits, office visits, outpatient visits and oncologist visits, were modeled with negative binomial regression. Since variable length of follow-up is allowed in the study design, we used inverse probability weight adjusted generalized linear models to estimate risk-adjusted annual total health care costs. Using a similar approach, we compared adjusted inpatient, pharmacy, office, outpatient, emergency and other costs between both groups.

Results: The study included 450 patients with TNBC and 1,807 patients without TNBC. At time of diagnosis, TNBC patients were younger (54 vs. 57, P&lt;0.001) than patients with no TNBC. After controlling with baseline differences, overall mortality risk rate for TNBC patients were over two times higher (HR: 2.15, P&lt;0.002). Stratified Kaplan-Meier (KM) analysis showed that the best survival rates were for stage I-III non-TNBC patients, followed by stage IV non-TNBC patients and stage I-III TNBC patients. The highest death rates occurred for stage IV TNBC patients. Adjusted comparison showed that patients with TNBC had significantly more annual number of hospitalizations, hospitalization days and number of ER visits relative to non-TNBC patients (1.28 vs. 0.95 P&lt;0.001, 10.20 vs. 6.07 P&lt;0.001, 1.30 vs. 0.93, P&lt;0.003). Although similar in annual total health cost, total adjusted inpatient costs for TNBC patients were almost 50% higher ($9,581 vs. $6,506, P&lt;0.001).

Conclusions: The economic and clinical burden of patients with TNBC is significant versus patients with breast cancer that are not triple negative.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-09-08.

Abstract P1-09-07: Survival, Health Care Utilization and Cost after Recurrence among Patients with Triple Negative Breast Cancer in a U.S. Managed Care Setting

Background: Triple negative breast cancer (TNBC) is characterized by the lack of expression of the genes for estrogen receptor, progesterone receptor or human epidermal growth factor recepter-2 and therefore it has a shorter recurrence-free interval. We compared the survival rates, health care costs and utilization of breast cancer recurrent patients who have triple negative versus no triple negative breast cancer.

Methods: Analyses were conducted using Impact Intelligence Oncology Management (IIOM) (2002-2009) linked with United Health administrative claims. Patients were followed from the time of initial breast cancer diagnosis until death, disenrollment or end of the observation period. Continuous enrollment was required during the observation period. Staging and estrogen and progesterone receptors (ER/PR) and HER2 status were obtained at time of initial diagnosis. Patients’ age, region, cancer stage, and comorbid conditions were controlled for risk-adjusted comparison. A stratified log-rank test was used to determine the equality of survival functions. Cox regression was used for the risk-adjusted survival analysis. Health care resource use during the follow-up period after recurrence was modeled with negative binomial regression. Inverse probability weight adjusted generalized linear models were used to estimate risk-adjusted total health care costs.

Results: The study included 289 recurrent breast cancer patients, out of which 87 (30%) had triple negative breast cancer. At time of recurrence, TNBC patients had similar age, plan, region, and cancer stage distribution relative to non-TNBC patients. During follow-up, TNBC patients had significantly lower survival rate (log-rank test P&lt;0.001). After controlling for baseline differences, the overall mortality risk rates for TNBC recurrent patients were almost three times higher than non-TNBC recurrent patients (HR:2.84, p=0.056). The risk-adjusted annual number of hospitalizations was also higher for TNBC patients with a recurrent event (1.65 vs. 1.13, p=0.05). There were no differences in health care costs after recurrence between TNBC and non-TNBC patients.

Conclusion: Although similar in health care costs, triple negative breast cancer is associated with higher mortality and number of hospitalizations after the recurrence of breast cancer.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-09-07.

Therapeutic effects of TACI-Ig on rat with adjuvant arthritis

Transmembrane activator and calcium modulator and cyclophilin ligand interactor-immunoglobulin (TACI-Ig) is a human fusion protein that binds and neutralizes both B lymphocyte stimulator (BLyS), a cytokine shown to be a key regulator of B cell maturation, proliferation and survival, and a proliferation-inducing ligand (APRIL). Rat adjuvant arthritis (AA) is an experimental animal model of rheumatoid arthritis (RA), which is mainly dependent on T cells and neutrophil-mediated cytokine production. The purpose of the present study was to investigate the effects of TACI-Ig on rat AA. Rat AA was induced by intradermal injection of 0·1 ml complete Freund's adjuvant (CFA). TACI-Ig (0·7, 2·1 and 6·3 mg/kg), recombinant human tumour necrosis factor-α receptor (rhTNFR) : Fc (2·8 mg/kg) and IgG-Fc (6·3 mg/kg) were administered subcutaneously every other day from days 16 to 34 after immunization. Arthritis was evaluated by arthritis global assessment and swollen joint count (SJC). The ankle joint and spleen were harvested for histopathological examination. Spleen index and thymus index were calculated. The levels of BLyS, interleukin (IL)-17, interferon (IFN)-γ, IgG1, IgG2a and IgM in AA rat spleen were measured by enzyme-linked immunosorbent assay. Administration of TACI-Ig significantly reduced the arthritis global assessment and SJC, decreased spleen index and ameliorated histopathological manifestations of rat AA. Suppressing the levels of BLyS, IL-17, IFN-γ and Ig in AA rat spleen were observed after administration of TACI-Ig. These results showed that TACI-Ig significantly inhibited the degree of rat AA, and the inhibitory effects might be associated with its ability to reduce BLyS, proinflammatory cytokines and Ig levels in spleen.

Backcrosses to Brassica napus of hybrids between B. juncea and B. napus as a source of herbicide-resistant volunteer-like feral populations

Introgression between genetically modified (GM) crops and wild relatives is considered to potentially modify the genetic background of the wild species. The emergence of volunteer-like feral populations through backcross of hybrids to the crop is also a concern. The progeny of spontaneous hybrids between mutant herbicide-resistant oilseed rape (Brassica napus) and wild B. juncea was obtained. Parents, F(2) and BC(1) to B. napus were planted together in the field so as to study their performance. The chromosome number of BC(1) followed a Normal distribution. Mendelian ratio of the herbicide-resistance gene was found. The F(2) produced less seeds than B. napus, and BC(1) had intermediate production. Herbicide-resistant BC(1) were not different of their susceptible counterparts for plant weight, seed weight and seed number, but most of them exhibited B. napus morphology and larger flowers than the susceptible BC(1). They displayed an important genetic variability allowing further adaptation and propagation of the herbicide-resistance gene. Pollen flow to susceptible plants within the mixed stand was observed. As a consequence, the resistant BC(1) produced with B. napus pollen could frequently occur and easily establish as a false feral crop population within fields and along roadsides.

Superiority of visipaque (iodixanol)-controlled density gradient over Ficoll-400 in adult porcine islet purification

OBJECTIVE

Sufficient and favorable biological functions of islets are major problems hindering xenotransplantation. The aim of the present study was to evaluate the effects on harvesting, purity, viability, and function of using improved Visipaque (iodixanol) and Ficoll-400 for adult porcine islet purification.

METHODS

Twelve adult porcine pancreata were randomly divided into an Iodixanol-University of Wisconsin (UW) group and a Ficoll-400-UW group according to the purification method. Porcine pancreata were isolated by collagenase digestion. After isolation and purification, the islet yield and purity were evaluated by dithizone staining, and islet function assessed by in vitro insulin release assays and in vivo islet xenotransplantation.

RESULTS

There were no marked differences in the islet yield before purification (5254.67 +/- 189.44 IEQ/g vs 5092.67 +/- 178.94 IEQ/g, P > .05). After purification, there were significantly more islets harvested in Iodixanol-UW group than in the Ficoll-400-UW group: 4222.00 +/- 228.84 IEQ/g vs 3036.83 +/- 79.60 IEQ/g (P < .05). Islets from the two groups showed satisfactory insulin secretory ability. There were no significant differences in islet survival times between the two groups in diabetic rats: 8.2 +/- 1.619 days vs 6.9 +/- 1.197 days (P > .05).

CONCLUSION

The improved iodixanol-UW density gradient method was superior to Ficoll-400 method to improve the number, viability, and insulin secret of purified adult porcine islets although the benefits did not improve in vivo survival.