Effect of lipids on insect cell growth and expression of recombinant proteins in serum-free medium

The lipid emulsion components of a serum-free insect cell medium were varied and evaluated for effects on cell growth and recombinant protein expression. The growth of High-Five(TM) cells was significantly affected by polyol Pluronic F-68 and Tween-80, but not by lipids. Pluronic was essential for cell growth, while Tween-80 was required to achieve maximum cell densities. A dose response effect was observed for Tween-80 with optimal cell growth at a concentration of 25 mg/l. Cholesterol had a minor effect on cell growth, but was essential for the expression of recombinant proteins. The expression of β-galactosidase (β-gal) was directly affected by cholesterol with optimal expression at a concentration of 5.4 mg/l. Vitamin E, important as an antioxidant to stabilize lipids, did not directly affect recombinant protein expression. Although lipids were not required for cell growth, the presence of lipids were required during the cell growth phase in order to achieve efficient infection with baculovirus. These studies help to define the important components, and range of concentrations, for lipid emulsions which can effectively replace serum in insect cell culture.

An unusual case of subclinical diffuse glucagonoma coexisting with two nodules in the pancreas: characteristic features on computed tomography

A lesion was discovered in the tail of the pancreas by ultrasonography performed during a health checkup for a 59-year-old Japanese man. Abdominal contrast-enhanced computed tomography (CE-CT) revealed strong enhancement in a 4-cm tumor in the pancreatic tail and in a 1-cm tumor in the pancreatic body. Serum glucagon levels were elevated to 54,405 pg/mL and a preoperative diagnosis of glucagonoma was made. The pancreatic tail and spleen were resected en bloc, along with a protruding tumor in the pancreatic body. However, histopathological evaluation revealed diffuse glucagonoma throughout the pancreas. When we retrospectively reviewed abdominal CE-CT after the operation, the entire pancreas was seen to be enlarged and diffusely enhanced by strong spots. Immunohistochemical examination using anti-CD31 demonstrated rich microvessels in two solid glucagonomas as well as microglucagonoma throughout the entire pancreas, indicating hypervascularity. Enlarged pancreas and diffuse enhancement of the pancreas by strong spots may be characteristic features of diffuse glucagonoma on abdominal CE-CT.

Tgf-beta-mediated FasL-Fas-Caspase pathway is crucial during palatogenesis

Programmed cell death, or apoptosis, is one of the fates of the medial edge epithelium (MEE) during palatal fusion. Transforming growth factor β (Tgf-β) signaling (such as Tgf-β3) is required for the disappearance of the MEE, but the relationship between Tgf-β3 and apoptosis remains unclear. Here we show that the Fas ligand (FasL)-Fas-Caspase extrinsic apoptosis pathway functions during palatal fusion in wild-type mice, but is not detectable in mice lacking Tgf-β3 (Tgf-β3 (-/-) ) or Tgfβr2 in the MEE (K14-Cre;Tgfbr2 (fl/fl)). Inhibition of the FasL-Fas system results in persistence of the midline epithelial seam (MES) and inhibition of caspase activity during palatal organ culture. Moreover, ectopic FasL protein induces apoptosis in MES of K14-Cre;Tgfbr2 (fl/fl) mice. Thus, we conclude that the FasL-Fas-caspase extrinsic apoptosis pathway is regulated by the Tgf-β3 signaling cascade and is essential for palatal fusion during craniofacial development.

BRAF mutation is a powerful prognostic factor in advanced and recurrent colorectal cancer

Background:

Activating mutation of KRAS and BRAF are focused on as potential prognostic and predictive biomarkers in patients with colorectal cancer (CRC) treated with anti-EGFR therapies. This study investigated the clinicopathological features and prognostic impact of KRAS/BRAF mutation in advanced and recurrent CRC patients.

Method:

Patients with advanced and recurrent CRC treated with systemic chemotherapy (n=229) were analysed for KRAS/BRAF genotypes by cycleave PCR. Prognostic factors associated with survival were identified by univariate and multivariate analyses using the Cox proportional hazards model.

Results:

KRAS and BRAF mutations were present in 34.5% and 6.5% of patients, respectively. BRAF mutated tumours were more likely to develop on the right of the colon, and to be of the poorly differentiated adenocarcinoma or mucinous carcinoma, and peritoneal metastasis. The median overall survival (OS) for BRAF mutation-positive and KRAS 13 mutation-positive patients was 11.0 and 27.7 months, respectively, which was significantly worse than that for patients with wild-type (wt) KRAS and BRAF (40.6 months) (BRAF; HR=4.25, P<0.001, KRAS13; HR=2.03, P=0.024). After adjustment for significant features by multivariate Cox regression analysis, BRAF mutation was associated with poor OS (HR=4.23, P=0.019).

Conclusion:

Presence of mutated BRAF is one of the most powerful prognostic factors for advanced and recurrent CRC. The KRAS13 mutation showed a trend towards poor OS in patients with advanced and recurrent CRC.

Distributions of FcγRIIa-131 and FcγRIIIa-158 polymorphisms and clinical response to cetuximab in Japanese patients with metastatic colorectal cancer (mCRC)

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Background: Polymorphisms in fragment C receptor (FcγR) are expected as a predictive biomarker of cetuximab (Cmab). Previous studies have convincingly confirmed the distributions (dists) of FcγR polymorphisms in Western population and shown the existence of linkage disequilibrium (LD) between FcγRIIa and FcγRIIIa polymorphisms. Meanwhile, the dists in Asian population have been unknown but a few studies for non-cancer patients have suggested the difference in dists between Asian and Western populations. We investigated the dists of FcγR polymorphisms and their association with clinical response to Cmab in Japanese mCRC patients.

Methods: Ninety-three patients with irinotecan/oxaliplatin/5-FU-refractory mCRC and treated by Cmab plus irinotecan or Cmab monotherapy were retrospectively registered from 8 centers in Japan. FcγR polymorphisms were determined from genomic DNA extracted from peripheral blood samples based on the Multiplex allele-specific PCR method. Comparisons according to FcγR polymorphisms were evaluated using Fisher's exact test for response rate (RR) and log-rank test for progression-free survival curves (PFS).

Results: The dists of FcγRIIa HH/HR/RR and FcγRIIIa VV/VF/FF were 68/30/2% and 4/40/56%, respectively (Table). The absence of LD between FcγRIIa and FcγRIIIa polymorphisms was confirmed (GENEPOP, p=0.526; Linkdis, p=0.146). Of 74 patients with KRAS wild-type and treated by Cmab plus irinotecan, no difference according to FcγR polymorphisms was observed in either RR (IIa: HH 37% vs. HR/RR 36%, p=1.00; IIIa: VV/VF 39% vs. FF 35%, p= 0.81) or PFS curves (IIa: HH vs. HR/RR, p=0.84; IIIa: VV/VF vs. FF, p=0.09). Similar results were seen in patients treated by cetuximab monotherapy.

Conclusions: This study clarified an ethnic difference in the frequencies of FcγR polymorphisms. Associations between the polymorphisms and clinical response to Cmab did not reach a statistical significance.

[Table: see text]

No significant financial relationships to disclose.

Evaluation of the seventh TNM classification system in patients with esophageal cancer receiving chemoradiotherapy

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Background: The new 7th edition of the TNM classification system is based on pathologic data of esophageal cancer underwent surgery alone. No report is available on the prognostic evaluation of the new staging system in patients treated with chemoradiotherapy (CRT). The objective of this study was to evaluate the prognostic impact of the 7th edition of the TNM staging system in esophageal cancer patients treated with CRT.

Methods: A retrospective review was performed of 301 consecutive patients who met the following inclusion criteria: (1) squamous cell carcinoma of thoracic esophagus; (2) total radiation dose ≥ 50 Gy; (3) concomitant chemotherapy consisting of 5-fluolouracil and platinum; (4) no previous thoracic radiotherapy or surgery. We compared the prognostic impact of the 6th and 7th editions of the TNM staging systems. Also, we compared the prognostic impact of stage group and prognostic group, which was newly defined in the 7th edition. Survival analysis was performed by using log-rank and Cox regression testing.

Results: Patients with stage I/II/III/IV were 52/42/54/153 and 57/46/128/70 according to 6th and 7th edition, respectively. Eighty-four patients were shifted to a lower stage in 7th edition compared with 6th edition, and most of these were from stage IV to III (n = 74). There were significant differences among stages I to III (p < 0.01, respectively) according to each edition. However, 7th edition poorly distinguishes between stages III and IV (p = 0.43). The survival curve of stage IV (lymph) almost completely overlapped with stage III (p = 0.69), although there were significant differences between stages IV (lymph) and IV (organ) (p = 0.04). Among the factors included in prognostic group in 7th edition, the histological grade and cancer site had no significant influence on patient survival, and T factor was only independent prognostic factors in multivariate analysis (p < 0.01).

Conclusions: Our study suggested several pitfalls in 7th TNM classification as prognostic factor in patients who received CRT.

No significant financial relationships to disclose.

Progression-free survival and time to progression as surrogate markers of overall survival in patients with advanced gastric cancer: Literature-based analysis of 36 randomized trials

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Background: We evaluated the potential of progression-free survival (PFS) and time to progression (TTP) to act as surrogates of overall survival (OS) in clinical trial settings by a comprehensive literature-based analysis.

Methods: Randomized trials of systemic chemotherapy for advanced gastric cancer were identified by comprehensive electronic and manual search. Correlations between PFS/TTP and OS were evaluated.

Results: Thirty-six trials with a total of 83 treatment arms and 10,484 patients were selected for analysis. The nonparametric Spearman rank correlation coefficient (p) between median PFS/TTP and OS was 0.70 (95% CI, 0.59 to 0.82) and the correlation coefficient between hazard ratios in PFS/TTP and OS was 0.80 (95% CI, 0.68 to 0.92). Correlation tended to be higher in non-Asian (p = 0.80; 0.61-0.98) than Asian trials (p = 0.67; 0.39-0.94), higher in trials reporting PFS (p = 0.85; 0.72-0.97) than in those reporting TTP (p = 0.60; 0.24-0.97), and higher in trials in patients with measurable lesions only (p = 0.91; 0.77-1.00) than in those including non-measurable lesions (p = 0.71; 0.50-0.93), albeit that none of these differences was significant.

Conclusions: Our results indicate that improvements in PFS/TTP in advanced gastric cancer strongly correlate with improvements in OS. PFS/TTP may be an appropriate surrogate for OS in clinical trials for advanced gastric cancer.

No significant financial relationships to disclose.

Evaluation of BRAF mutation as a powerful prognostic factor in advanced and recurrent colorectal cancer

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Background: Alterations in the RAS/RAF/ERK signaling pathways frequently occur in colorectal cancer (CRC). KRAS mutations preclude responsiveness to EGFR-targeted therapies for CRC patients. However, prognostic significance of KRAS mutation is still controversial. The aim of this study is to investigate clinicopathological features of KRAS mutation in codon 12 and 13 as well as of BRAF mutation, and to validate prognostic impact of KRAS/BRAF mutation in advanced and recurrent CRC.

Methods: The population consisted of 230 unselected patients who had undergone first-line chemotherapy for advanced and recurrent CRC between November 2002 and June 2010. Cycleave PCR was performed to detect a point mutation at codon 12, 13 or 61 in KRAS, and the V600E mutation in BRAF. Prognostic factors associated with survival were identified using univariate and multivariate logistic and/or Cox proportional hazards analyses.

Results: KRAS mutations were present in 34.8% (n= 80) of patients, including 23.5% (n = 54) in codon 12, 11.3% (n = 26) in codon 13, and 0% in codon 61. 6.5% (n = 15) of patients had BRAF mutation. None of the CRC patients carried both KRAS and BRAF mutations. The primary tumor lesions were located on the right side of the colon in 60% of the BRAF mutant patients (p=0.0371). Furthermore, BRAF mutant was significantly associated with the pathological subtypes of poorly differentiated adenocarcinoma/mucinous carcinoma (p<0.0001) and peritoneal metastasis (p=0.0059). The median overall survival for BRAF mutant and KRAS 13 mutant patients was 11.0 and 27.7 months, respectively, which was significantly worse than that for KRAS wild-type (wt)/BRAF wt (40.6 months) (BRAF; HR=3.89, 95% CI 1.83-8.24, p<0.001, KRAS13; HR=2.03, 95% CI 1.10-3.74, p=0.024). After adjustment for significant features by multivariate Cox regression analysis, BRAF mutation was associated with poor overall survival (HR, 3.70, 95% CI, 1.48-9.28; p=0.005), together with performance status 2.

Conclusions: This retrospective analysis shows that clinicopathological features of CRC patients with BRAF mutations seem to be distinct from those with wild type BRAF. BRAF mutation is one of the most powerful prognostic factors in advanced and recurrent CRC.

No significant financial relationships to disclose.

Phase II study of combination chemotherapy with biweekly cetuximab and irinotecan for wild-type KRAS metastatic colorectal cancer refractory to irinotecan, oxaliplatin, and fluoropyrimidines

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Background: Weekly cetuximab and irinotecan is a standard regimen in heavily pretreated patients with metastatic colorectal cancer (MCRC). The aim of this study was to prospectively evaluate the efficacy of combination chemotherapy with biweekly cetuximab and irinotecan in patients with pretreated MCRC harboring wild-type KRAS.

Methods: Patients with wild- type KRAS MCRC that had progressed after chemotherapy with irinotecan, oxaliplatin, and fluoropyrimidine were included in this study. Cetuximab was administered at 500 mg/m2 biweekly with irinotecan. The primary endpoint was response rate. The secondary endpoints included adverse events, progression-free survival, and overall survival. The pharmacokinetics of cetuximab was also evaluated in five patients.

Results: From May, 2009 to February, 2010, a total of 31 patients were enrolled from five institutions. One patient was not eligible. Among the 30 assessable patients, ECOG PS was 0 in 12, 1 in 16, and 2 in two patients. The objective response rate was 30.0% (95% confidence interval [CI], 14.7-49.4), and the disease control rate (complete response, partial response, or stable disease) was 76.7% (95%CI, 61.4-92.3). The median progression-free survival was 5.3 months (95%CI, 3.4-7.3). Grade 3 skin toxicity was observed in 3 patients (10%), and treatment related death due to pneumonia occurred in one patient.

Conclusions: The efficacy data are similar to those of standard dose of cetuximab plus irinotecan. Combination chemotherapy with biweekly cetuximab and irinotecan is effective for pretreated metastatic wild-type KRAS MCRC.

No significant financial relationships to disclose.