Minkyu Jung

Growth of CdTe epitaxial films on p‐InSb(111) by temperature gradient vapor transport deposition

The growth of high quality CdTe epitaxial films on p‐InSb(111) by a simple method of temperature gradient vapor transport deposition was carried out to investigate the possibility of the existence of a two‐dimensional electron gas with high mobility at CdTe/InSb heterointerfaces. From the x‐ray diffraction analysis, the grown layer was found to be a CdTe epitaxial film. Photoluminescence measurements at 15 K showed that a CdTe film grown on InSb(111) in the temperature range between 180 and 280 °C appeared to have an optimum crystal perfection at a substrate temperature of about 245 °C. These results also indicated that the CdTe films grown above 245 °C contained a significant problem due to interdiffusion from the InSb substrates during the growth.

PTEN Deficiency as a Predictive Biomarker of Resistance to HER2-Targeted Therapy in Advanced Gastric Cancer

Background: To investigate the role of the phosphoinositide 3-kinase (PI3K) pathway activation in human epidermal growth factor receptor 2 (HER2)-targeted therapy. Methods: We evaluated the predictive roles of PI3K, catalytic alpha (PIK3CA), and phosphatase and tensin homolog (PTEN) in HER2-based therapy (either trastuzumab or lapatinib). PTEN expression and PIK3CA mutation were analyzed using immunohistochemistry and pyrosequencing. Results: Forty-eight patients received trastuzumab (n = 39) or lapatinib (n = 9) combination chemotherapy. PTEN loss was found in 47.9% (n = 23), but no PIK3CA mutations were identified. Twenty-six (54.1%) patients responded to HER2-based therapy, without a significant difference between patients with PTEN loss and those without (52.2 vs. 56.0%). Among the patients with responsive disease, time to best response did not differ by PTEN status, but the duration of response was significantly shorter for patients with PTEN loss (median 4.2 vs. 6.1 months, p = 0.04). In addition, patients with PTEN loss had a significantly shorter progression-free survival time (median 4.9 vs. 7.3 months, p = 0.047). Conclusions: PTEN deficiency is an important predictive marker for early resistance to HER2 inhibitor treatment in gastric cancer patients. This finding may be useful for the development of drug combinations and identification of patients who need a modified treatment strategy.

MMP-2 as a putative biomarker for carcinomatosis in gastric cancer

BACKGROUND/AIMS We evaluated matrix metalloproteinase (MMP)-2 and -9 as novel biomarkers in the body fluid of advanced gastric cancer with peritoneal and pulmonary metastasis. METHODOLOGY MMPs activity from zymography was quantified with ELISA to determine the cut-off expression levels of MMPs. The expression of MMPs in patient samples were evaluated with ELISA and compared with clinical parameters. Ascitic CEA (aCEA) and pleural CEA (pCEA) were measured by chemiluminescent enzyme immunoassay. RESULTS MMP-2 and -9 cut-off levels were 8.6ng/mL and 0.14ng/mL, respectively. Ascitic fluid cytology of 93 patients revealed a positivity of 55.9% while for MMP-2 it was 93.3%, for MMP-9 35.2% and for aCEA 86.7%. Combining biomarkers, the positivity increased to 99.1% in patients with MMP-2 or aCEA expression. We found a negative correlation between MMP-2 expression and survival when a new prognostic cut-off of 22.6ng/mL was used. Patients with high MMP-2 expression (≥22.6ng/mL) had a median survival of 45 days and those with low MMP-2 expression (<22.6ng/mL) had a median survival of 69 days (p<0.01). CONCLUSIONS These results suggest that MMPs could be used as diagnostic markers in body fluid and MMP-2 might be a prognostic marker in ascites of advanced gastric patients with disseminated metastasis.

Chemokine growth‐regulated oncogene 1 as a putative biomarker for gastric cancer progression

Gastric cancer (GC) is a heterogeneous disease that is not well detected by current tumor markers. Identifying molecular markers that can predict the potential for tumor progression is important for appropriate individualized therapy. Using the Cancer Metastasis Research Center microarray database (17K cDNA microarray), we identified genes that were differentially expressed between 96 cancer and 98 normal gastric tissues using significant analysis of microarrays. From these, we selected genes that were overexpressed more than twofold in tumor tissues that encode secreted proteins. The selected genes were validated with ELISA using the sera of 96 GC patients and 48 healthy donors. Our first round of selection included 6510 genes that were differentially expressed between 96 cancer and 98 normal gastric tissues with a minimal false discovery rate of 0.005%. Out of those genes, we picked 386 that encoded secreted proteins based on the SOURCE database. Of these genes, we focused on 55 that were overexpressed more than twofold in GC compared to normal tissues. With Ingenuity Pathway Analysis, we found 34 genes related to cancer. One in particular, chemokine growth‐regulated oncogene 1, CXCL1, has been linked to cancer progression in various cancer types, but not yet to GC. Levels of CXCL1 in serum samples of GC patients were significantly higher compared with healthy donors (P < 0.05). Within GC patients, CXCL1 serum levels increased according to tumor stage and lymph node metastasis. The CXCL1 gene appears to be a candidate marker for GC progression. (Cancer Sci 2010)

Evaluation of prognostic values of clinical and histopathologic characteristics in diffuse large B-cell lymphoma treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone therapy

The relationship between histopathologic characteristics and treatment outcomes in patients with diffuse large B-cell lymphoma (DLBCL) treated with rituximab-based immunochemotherapy needs re-evaluation. Patients with newly diagnosed DLBCL treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) were evaluated with respect to clinical characteristics, treatment efficacy, and survival. Immunohistochemistry of bcl-2, CD10, bcl-6, and MUM-1 was performed and patients were sub-classified as germinal center B-cell-like (GCB) or non-GCB type according to the Hans algorithm. There was no significant difference in overall survival (OS) between patients with GCB and those with non-GCB. Although there was no significant difference in OS between high-intermediate and high risk groups as classified by the standard International Prognostic Index (IPI; p = 0.50), all three groups with the revised IPI had a clear-cut separation for event-free survival and OS. The revised IPI better predicted survival than did the standard IPI in patients with DLBCL treated with R-CHOP. The Hans classification had no prognostic value.

Oncogenic BRAF fusions in mucosal melanomas activate the MAPK pathway and are sensitive to MEK/PI3K inhibition or MEK/CDK4/6 inhibition

Despite remarkable progress in cutaneous melanoma genomic profiling, the mutational landscape of primary mucosal melanomas (PMM) remains unclear. Forty-six PMMs underwent targeted exome sequencing of 111 cancer-associated genes. Seventy-six somatic nonsynonymous mutations in 42 genes were observed, and recurrent mutations were noted on eight genes, including TP53 (13%), NRAS (13%), SNX31 (9%), NF1 (9%), KIT (7%) and APC (7%). Mitogen-activated protein kinase (MAPK; 37%), cell cycle (20%) and phosphatidylinositol 3-kinase (PI3K)-mTOR (15%) pathways were frequently mutated. We biologically characterized a novel ZNF767-BRAF fusion found in a vemurafenib-refractory respiratory tract PMM, from which cell line harboring ZNF767-BRAF fusion were established for further molecular analyses. In an independent data set, NFIC-BRAF fusion was identified in an oral PMM case and TMEM178B-BRAF fusion and DGKI-BRAF fusion were identified in two malignant melanomas with a low mutational burden (number of mutation per megabase, 0.8 and 4, respectively). Subsequent analyses revealed that the ZNF767-BRAF fusion protein promotes RAF dimerization and activation of the MAPK pathway. We next tested the in vitro and in vivo efficacy of vemurafenib, trametinib, BKM120 or LEE011 alone and in combination. Trametinib effectively inhibited tumor cell growth in vitro, but the combination of trametinib and BKM120 or LEE011 yielded more than additive anti-tumor effects both in vitro and in vivo in a melanoma cells harboring the BRAF fusion. In conclusion, BRAF fusions define a new molecular subset of PMM that can be targeted therapeutically by the combination of a MEK inhibitor with PI3K or cyclin-dependent kinase 4/6 inhibitors.

Cumulative Metformin Use and Its Impact on Survival in Gastric Cancer Patients After Gastrectomy.

OBJECTIVE The aim of this study was to evaluate the association between metformin and survival of gastric cancer (GC) patients. BACKGROUND Metformin has recently received attention as a potential anticancer treatment. However, no study has shown the survival benefit of metformin for GC patients. METHODS A total of 1974 GC patients who underwent curative gastrectomy were compared for survival according to groups; 132 diabetic patients treated with metformin, 194 diabetic patients without metformin, and 1648 non-diabetic patients. RESULTS During the median follow-up period of 6.2 years (interquartile range, 4.7-7.8 years), 381 patients (19.3%) died, including 302 (15.3%) who died from GC. The non-diabetic patients had significantly better recurrence-free survival (RFS; P < 0.0001), cancer-specific survival (CSS; P = 0.006), and overall survival (OS; P < 0.0001). However, the diabetic patients treated with metformin had a significantly better prognosis than those who were not (OS: hazard ratio [HR] = 0.584, 95% confidence interval [CI], 0.369-0.926; CSS: HR = 0.57, 95% CI, 0.334-0.975; RFS: HR = 0.633, 95% CI, 0.410-0.977), and metformin treatment prolonged survival in diabetic patients to a rate comparable to that in non-diabetic patients. In multivariable analysis using the Cox proportional hazard model with time-dependent covariates, each cumulative 6 months of metformin use was significantly associated with a decreased risk of recurrence, cancer-specific mortality, and all-cause mortality (RFS: HR = 0.864, 95% CI, 0.797-0.937; CSS: HR = 0.865, 95% CI, 0.782-0.958; OS: HR 0.870, 95% CI, 0.801-0.945). CONCLUSIONS The increased cumulative duration of metformin use decreased the recurrence, all-cause mortality, and cancer-specific mortality rates among GC patients with diabetes who underwent gastrectomy.

Effects of microsatellite instability on recurrence patterns and outcomes in colorectal cancers

Background:Among colorectal cancers (CRCs), high-frequency microsatellite instability (MSI-H) is associated with a better prognosis, compared with low-frequency MSI or microsatellite stability (MSI-L/MSS). However, it is unclear whether MSI affects the prognosis of recurrent CRCs.Methods:This study included 2940 patients with stage I–III CRC who underwent complete resection. The associations of MSI status with recurrence patterns, disease-free survival (DFS), overall survival from diagnosis to death (OS1), and overall survival from recurrence to death (OS2) were analysed.Results:A total of 261 patients (8.9%) had MSI-H CRC. Patients with MSI-H CRC had better DFS, compared to patients with MSI-L/MSS CRC (hazard ratio (HR): 0.619, P<0.001). High-frequency microsatellite instability CRC was associated with more frequent local recurrence (30.0% vs 12.0%, P=0.032) or peritoneal metastasis (40.0% vs 12.3%, P=0.003), and less frequent lung (10.0% vs 42.5%, P=0.004) or liver metastases (15.0% vs 44.7%, P=0.01). Recurrent MSI-H CRC was associated with worse OS1 (HR: 1.363, P=0.035) and OS2 (HR: 2.667, P<0.001). An analysis of patients with colon cancer yielded similar results.Conclusions:Recurrence patterns differed between MSI-H CRC and MSI-L/MSS CRC, and recurrent MSI-H CRCs had a worse prognosis.

Prognostic and Predictive Value of Carcinoembryonic Antigen and Cytokeratin-19 Fragments Levels in Advanced Non-Small Cell Lung Cancer Patients Treated with Gefitinib or Erlotinib

Purpose The prognostic and predictive value of pretreatment serum levels of carcinoembryonic antigen (CEA) and cytokeratin-19 fragments (CYFRA 21-1) were assessed in advanced non-small cell lung cancer (NSCLC) patients treated with gefitinib or erlotinib. Materials and Methods Pretreatment CEA and CYFRA 21-1 were measured in 123 advanced NSCLC patients receiving gefitinib or erlotinib. High CEA levels (h-CEA) were significantly associated with females, patients with adenocarcinoma, and non-smokers. Results Low CYFRA 21-1 levels (l-CYFRA) were significantly associated with a good performance status (ECOG PS 0-1). The overall response rate (RR) was 27.6%, and higher RR was associated with adenocarcinoma, h-CEA, and epidermal growth factor receptor (EGFR) mutation. Patients with h-CEA had significantly longer progression-free survival (PFS) (p=0.021). Patients with l-CYFRA had significantly longer PFS and overall survival (p=0.006 and p<0.001, respectively). Of note, h-CEA and l-CYFRA had good prognosis in patients with unknown EGFR mutation status or patients with squamous cell carcinoma (p=0.021 and p=0.015, respectively). A good ECOG PS (HR=0.45, p=0.017), h-CEA (HR=0.41, p=0.007), l-CYFRA 21-1 (HR=0.52, p=0.025), and an EGFR mutation (HR=0.22, p<0.001) were independently predictive of a longer PFS. Conclusion h-CEA and l-CYFRA 21-1 may be prognostic and predictive serum markers for higher response and longer survival in patients with advanced NSCLC receiving gefitinib or erlotinib, especially in patients with unknown EGFR mutation status or patients with squamous cell carcinoma.

Overexpression of Class III Beta Tubulin and Amplified HER2 Gene Predict Good Response to Paclitaxel and Trastuzumab Therapy

Through this study, we aimed to validate several biomarkers that have been known to possibly predict the outcomes of the trastuzumab and paclitaxel (TP). Human epidermal growth factor 2 (HER2) positive metastatic breast cancer (MBC) patients who had been treated with TP in single institute from 2006 to 2009 were included in this study. For procured formalin fixed paraffin embedded tumor tissues, HER2 amplification index (AI) and polymorphisms of the immunoglobulin G fragment C receptors (FCGR) were assessed as biomarkers to the trastuzumab and expression of class III beta tubulin (bTubIII) was evaluated as a predictive factor to the paclitaxel. Of 46 patients treated with TP, 27 patients could be evaluated for HER2 AI, 31 for bTubIII, and 26 for FCGR gene polymorphism. The median of the HER2 AI was 5.0 (range, 1.4−15.5) and a higher HER2 AI (≥5.0) was significantly correlated with better response rate (RR) (80% vs. 42%, P = 0.049) and longer progression-free survival (PFS) (13.6 vs. 6.9 months, P = 0.023). High bTubIII expression showed higher RRs than did low expression (81% vs. 40%, P = 0.040) in addition to longer PFS (16.2 months vs. 8.8 months, P = 0.04). However, polymorphisms in FCGR 2A-H131R or FCGR 3A-V158F were not predictive of RR or PFS. Our results suggest that a high HER2 AI and high bTubIII expression could be predictive of the outcomes to TP therapy but no evidence was found in terms of FCGR polymorphisms.