Rapid 5-fluorouracil plasma quantification by immunoassay: Validation with FOLFOX6 clinical samples

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Background: 5-fluorouracil (5-FU) is one of the most widely used chemotherapy agents in the treatment of colorectal cancer. Studies over the last 30 years have demonstrated wide pharmacokinetic variability of 5-FU which can lead to undue toxicity and suboptimal treatment. Recent clinical studies have demonstrated that managing plasma 5-FU levels and adjusting doses to target steady state concentrations effectively minimizes toxicity and improves outcome.

Methods: An existing immunoassay using a novel antibody to 5-FU was modified to directly quantify 5-FU in patient plasma samples without any sample pretreatment. The assay was adapted to Beckman Coulter AU analyzers and to Roche COBAS c 111 analyzer. Method comparison to LC-MS/MS, limit of detection (LoD), lower limit of quantitation (LLoQ), precision, and linearity of the assay were evaluated. The assay was also validated by testing samples of patients being treated by modified FOLFOX6 from an on-going clinical trial ( NCT00943137 ).

Results: The modified immunoassay was confirmed to have a linear reportable range from 85 to 18,000ng/mL and a LoD of 52ng/mL. The immunoassay was established to have good precision (CV<6%) around the medical decision points for FOLFOX and FOLFIRI regimens. Method comparison of the immunoassay obtained by testing 58 clinical samples from patients under 5-FU treatment provides excellent correlation to LC- MS/MS: Deming slope 1 ± 0.05, R > 0.98. Another 82 samples of patients on modified FOLFOX6 regimen from clinical trial (( NCT00943137 ) were tested using the immunoassay and range of these sample were reported to be from 95 to 2,970 ng/mL.

Conclusions: The assay provided the performance required to rapidly quantify 5-FU plasma concentrations. It was fast (time to 1st result < 10 minutes), precise, correlated well to a physical method, required only 100uL sample on the analyzer and 7ul for actual testing per assay, and was easily adapted to a variety of clinical analyzers. Clinical and pharmacokinetic laboratories could use this assay to introduce an evidence-based approach to optimize 5-FU dosing that would have higher throughput, simpler methodology, and require less labor, space or expense than the physical methods.

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Primary malignant melanoma of the esophagus: a study of clinical features, pathology, management and prognosis

Primary malignant melanoma of the esophagus (PMME) is a rare disease that is characterized by aggressive invasion, early metastasis, and poor prognosis. Treatment protocols are not well-established. To understand this condition more precisely, we performed a retrospective review of eight cases of PMME diagnosed at the Thoracic Department of the Cancer Center at Sun Yat-Sen University between 1985 and 2009. Eight PMME patients (five men and three women) with a mean age of 58 years (range: 48 to 72 years) were included. Dysphagia was the most common presenting symptom. All patients underwent an Ivor-Lewis esophagogastrectomy and lymph node dissection with postoperative adjuvant chemotherapy. One patient with stage III/pT4N0M0 underwent postoperative chemotherapy plus radiotherapy. Four patients died of distant metastases. The median survival time was 28 months (range: 11 months to 6 years). Our data confirm that PMME is a highly aggressive disease with a poor prognosis. If the diagnosis is suspected or confirmed as PMME, and the patients have no distal metastases or extensive lymph node enlargement, we suggest that surgery should be the first choice of treatment. With regard to adjuvant therapy, we recommend the addition of chemotherapy. The role of radiotherapy remains questionable and requires further investigation.

Phase II trial of irinotecan and cisplatin combination as first-line chemotherapy in patients with advanced esophageal squamous-cell carcinoma: An interim report

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Background: Although the irinotecan and cisplatin combination has been used in esophageal cancer treatment, we tested the combination specifically in unresectable or metastatic esophageal squamous cell carcinoma with different doses to decrease the toxicity and keep the efficacy.

Methods: Patients were eligible if they had histologic proof of unresectable or metastatic squamous cell carcinoma of the esophagus, between 18-75 years of age with a Karnofsky performance status ≥ 80. No prior chemotherapy was allowed. Patients were treated with irinotecan 130 mg/m2 and cisplatin 60 mg/m2 repeated 3 weeks. Response was evaluated every two cycles of treatment by using RECIST criteria. The sample size was calculated using Simon's 2-stage design. The primary end point of the study was objective response rate. The second end points are PFS and toxicity. Accrual was planned to a total of 46 patients with the targeted response rate of 50%. The first stage requires at least 7 or more out of 16 patients to have a confirmed partial or complete response before proceeding to the second stage.

Results: Twenty one patients have been enrolled so far, of which 16 patients were assessable for response. The overall response rate was 43.8%(7/16), including one complete response (6.3%) and six partial response (37.5%). Among 13 patients who presented with dysphagia at baseline, 10 (62.5%) had the symptom either completely resolved or significantly improved. The most common toxicities were neutropenia, diarrhea and alopecia. Seven patients (33.3%) developed grade 3 neutropenia and one had (4.8%) with febrile neutropenia. One patient (4.8%) had grade 3 diarrhea. There were no treatment-related deaths.

Conclusions: The combination of irinotecan plus cisplatin with lower doses showed equivalent efficacy and less toxicity in patients with unresectable or metastatic squamous-cell carcinoma of the esophagus. The study is ongoing.

No significant financial relationships to disclose.

Study of genotypic variations and protein expression of the xCT subunit of cystine/glutamate transporter in pancreatic cancer

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Background: The plasma membrane xCT cystine-specific subunit of the cystine/glutamate transporter contributes to chemotherapy resistance in pancreatic cancer by regulating intracellular glutathione levels and protecting cancer cells against oxidative stress. We previously noted that the rs7674870 single nucleotide polymorphism (SNP) of xCT correlated with overall survival in pancreatic cancer and may be predictive of platinum resistance. There are no data regarding xCT protein expression in pancreatic cancer or the functional significance of this SNP.

Methods: Paraffin-embedded core and surgical biopsy tumor specimens from 49 patients with metastatic pancreatic adenocarcinoma were analyzed by immunohistochemistry (IHC) using an xCT specific antibody (Novus Biologicals). xCT protein IHC expression scores (product of intensity and percentage of staining cells) were analyzed in relation to overall survival and genotype of the patients using the one factor ANOVA test, Kaplan-Meier plot, log-rank test, and Cox regression analysis. Overall survival was measured from the date of diagnosis to the date of death or last follow-up.

Results: Positive xCT expression was detected in 38 (78%) of the 49 samples, and 9 (18%) patients had high levels of expression. High xCT expression was associated with lower overall survival as compared with low expression (5.1 months versus 8.8 months; p = 0.119). In a multivariate Cox regression model with adjustment for prognostic parameters of age, sex, performance status and CA19-9 level, high xCT expression was associated with a 2.1-fold increased risk of death (p = 0.096). Performance status also correlated with overall survival (p = 0.027). Preliminary analysis on the genotype-phenotype association (n = 12) indicated that xCT expression was higher with the TT genotype than the TC/CC genotype (p = 0.115), which is consistent with the previous observation that the TT genotype was associated with reduced survival.

Conclusions: These data provide supporting evidence for a possible role of cystine/glutamate transporter xCT subunit in pancreatic cancer progression and survival. Further pharmacogenomic and clinicopathologic studies are ongoing.

No significant financial relationships to disclose.

Differential expression of small ubiquitin-like modifier family of proteins in patients with colorectal adenocarcinoma

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Background: The cytotoxic effects of radiation and chemotherapy are mediated in part by DNA damage. The small ubiquitin-like modifier (SUMO) family of proteins regulates DNA repair pathways by activating factors involved in homologous recombination (HR) or non- homologous end joining (NHEJ). Our objective was to determine the potential role of SUMO proteins in patients with colorectal cancer.

Methods: We first assessed two established colorectal cancer cell lines (HCT116 and HT29) and two normal colonic mucosa cell populations utilizing ultra high-throughput expression analysis (Solexa) to examine differential expression of genes involved in SUMOylation (SAE1, SAE2, PIAS-1, and DNAPKcs). To verify the clinical relevance of SUMOylation in colorectal cancer, we obtained archived specimens from patients with colorectal cancer (n=51) and examined the expression of these proteins in both benign and malignant tissue by immunohistochemistry (IHC).

Results: Ultra high-throughput expression analysis of cancer and normal cells revealed a 10 to 15-fold upregulation of SAE2 (heterodimer of the E1 activation enzyme in SUMOylation), a 10 to 11-fold upregulation of DNAPKcs (catalytic subunit in NHEJ repair pathway), and a 6-fold upregulation of SAE1 in cancer cells. In contrast, PIAS-1 showed similar expression levels between cancer and normal colonic cells. By IHC, SAE1 and SAE2 were highly expressed in 65% and 53% of tumor specimens, respectively; but only in 7% and 0% of normal tissues, respectively. DNAPKcs was also highly expressed in tumor tissues (63%) with corresponding low expression (0%) in normal tissues. Corroborating the cell line results, PIAS-1 was infrequently expressed in both tumor (10%) and normal tissues (0%).

Conclusions: We are the first to demonstrate the differential expression of SUMO proteins in colorectal cancer cell lines and in clinical specimens. SUMO proteins have a role in DNA repair and their expression in colorectal cancer may modify tumor response to chemoradiotherapy.

No significant financial relationships to disclose.

High dose human insulin and insulin glargine promote T24 bladder cancer cell proliferation via PI3K-independent activation of Akt

BACKGROUND

This study was to investigate the effects of human insulin and insulin glargine on proliferation of T24 human bladder cancer cells and the implication of the PI3K/Akt and MEK/ERK1/2 pathways.

METHODS

After exposure to insulin or glargine at the indicated concentrations for certain time courses, in the absence or presence of inhibitor for MEK (PD98059) or PI3K (LY294002), T24 cell proliferation was evaluated by CCK-8 assay. Phosphorylation of Akt and ERK1/2 was analyzed by Western blot.

RESULTS

Insulin and glargine similarly induced phosphorylation of Akt and slight increases in T24 cell proliferation at 10-100IU/L. LY294002 remarkably reduced T24 cell proliferation in all groups. However, in the presence of LY294002, cell growth was still promoted by insulin and glargine relative to LY294002-treated group. Accordingly, LY294002 profoundly reduced protein levels of pAkt, while insulin and glargine increased pAkt in T24 cells pretreated with LY294002 as compared with cells treated with LY294002 alone. PD98059 reduced pERK while enhanced T24 cell proliferation. Insulin and glargine increased pERK at 15, 30, 60 min, not at 24h.

CONCLUSIONS

High dose human insulin and insulin glargine similarly promoted T24 bladder cancer cell proliferation via PI3K-independent activation of Akt.

First Report of Bacterial Wilt Caused by Ralstonia solanacearum on Mesona chinensis in China

Jellywort (Mesona chinensis Benth) is an herbaceous plant in the Lamiaceae (mint) family. The plant is referred to as 'Xiancao' (weed from angels) in Chinese and primarily used to make grass jelly, a popular refreshing drink. Currently, Xiancao cultivation is a fast-growing industry with a high profit margin in southern China. An estimated 7,000 ha is grown with a value of more than $50 million USD. In June, 2009, a wilting disease of Xiancao was observed in Guangdong and the neighboring Guangxi and Fujian provinces with incidence up to 50% in the severest case. Affected plants initially show withering symptoms on apical leaves during the daytime with recovery at night. As the disease develops, withering leaves spread downward, eventually encompassing the whole plant. Leaves lose vigor but remain green. After 3 to 4 days, wilting becomes irreversible. Roots and basal stem tissues blacken and rot, leading to plant death. Longitudinal sectioning of the basal stem shows browning of vascular tissues with whitish ooze visible when compressed. To investigate the disease etiology, 12 Xiancao plants from three cultivars showing typical wilting symptoms were collected from a production field in Zengcheng City of Guangdong Province in June 2010. A total of 27 bacterial isolates showing large, elevated, and fluidal colonies with a pale red center were isolated from vascular tissue on tripheny tetrazolium chloride medium (3) after incubation at 30° for 2 days. Fifteen 45-day-old Xiancao plants (cv. Zhengcheng 1) were inoculated by injection of 20 μl of bacterial suspension (1 × 10⁸ CFU/ml) into the middle stem. Sterile water was used as a negative control. After 4 to 6 days of incubation in a greenhouse (28 to 30°), all (15 of 15) inoculated plants developed wilting symptoms as described above. The same bacterium was reisolated from inoculated plants. The five negative control plants did not show any wilting symptoms. With the same artificial inoculation procedure, this bacterium also caused similar wilting disease in tobacco, potato, tomato, pepper, and eggplant. An inoculation test with a tomato strain of Ralstonia solanacearum resulted in similar symptoms. On the basis of symptomatology and bacterial culture characteristics, R. solanacearum (formerly Pseudomonas solanacearum) was suspected as the causal agent. For confirmation, the universal bacterial 16S rDNA primer set E8F/E1115R (1) was used to amplify DNA from pure culture. A 1,027-bp DNA sequence was obtained and deposited in GenBank with Accession No. HQ159392. BLAST search against the current version of GenBank database showed 100% similarity with the 16S rDNA sequences of 26 R. solanacearum strains. Furthermore, primer set 759/760 (4) amplified a specific 280-bp fragment. Along with the result from multiplex PCR (2), the bacterium was identified as R. solanacearum Phylotype I. To our knowledge, this is the first report of a disease caused by R. solanacearum on M. chinensis. References: (1) G. Baker et al. J. Microbiol. Methods 55:541, 2003. (2) M. Fegan and P. Prior. Page 449 in Bacterial Wilt Disease and the Ralstonia solanacearum Species Complex. C. Allen et al., eds. The American Phytopathological Society. St. Paul, MN, 2005. (3) A. Kelman, Phytopathology 44:693, 1954. (4) N. Opina et al. Asia Pac. J. Mol. Biol. Biotechnol. 5:19, 1997.

Marek's disease resistant/susceptible MHC haplotypes in Xiayan chickens identified on the basis of BLB2 PCR-RFLP and BLB2/BF2 sequence analyses

1. The aim was to analyse the variability of the BLB2/BF2 genes of Xiayan chickens to identify homozygous birds with resistance or susceptibility to Marek's disease (MD). 2. The experiment used two lines: birds from a common line were divided into Group A (unvaccinated) and Group B (vaccinated with herpesvirus of turkeys (HVT)); and birds from an MD-resistant line were divided into Group C (unvaccinated) and Group D (vaccinated with HVT). They were challenged intra-abdominally with Marek's disease virus (MDV) and genomic DNA extracted from peripheral blood lymphocytes so that polymorphism of the BLB2/BF2 genes could be analysed using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) and nucleotide sequence analysis. 3. A 374-bp fragment of the BLB2 gene was amplified from the samples and, after digesting with restriction enzymes Alu I, Cai I, Cfr I, Hin1 I, Hinf I and Rsa I for RFLP analysis, the 6 electrophoretic patterns were analysed. Seven homozygous genotypes were found and used tentatively to identify alleles of the BLB2 gene. 4. A 765-bp fragment of the BF2 gene was amplified from the 7 samples for cloning and sequencing. 5. Six homozygous birds were confirmed from the sequenced BLB2/BF2 gene. Four birds were resistant to MD. Three birds had identical nucleotide sequences and were highly homologous with MHC haplotype B⁶, which is MD resistant. One bird had high homology with the highly MD-resistant B²¹ haplotype, and two birds were susceptible and highly homologous to the B¹⁹ haplotype, which is highly MD susceptible.