Sae Won Han

Targeted sequencing of cancer-related genes in colorectal cancer using next-generation sequencing.

Recent advance in sequencing technology has enabled comprehensive profiling of genetic alterations in cancer. We have established a targeted sequencing platform using next-generation sequencing (NGS) technology for clinical use, which can provide mutation and copy number variation data. NGS was performed with paired-end library enriched with exons of 183 cancer-related genes. Normal and tumor tissue pairs of 60 colorectal adenocarcinomas were used to test feasibility. Somatic mutation and copy number alteration were analyzed. A total of 526 somatic non-synonymous sequence variations were found in 113 genes. Among these, 278 single nucleotide variations were 232 different somatic point mutations. 216 SNV were 79 known single nucleotide polymorphisms in the dbSNP. 32 indels were 28 different indel mutations. Median number of mutated gene per tumor was 4 (range 0–23). Copy number gain (>X2 fold) was found in 65 genes in 40 patients, whereas copy number loss (<X0.5 fold) was found in 103 genes in 39 patients. The most frequently altered genes (mutation and/or copy number alteration) were APC in 35 patients (58%), TP53 in 34 (57%), and KRAS in 24 (40%). Altered gene list revealed ErbB signaling pathway as the most commonly involved pathway (25 patients, 42%). Targeted sequencing platform using NGS technology is feasible for clinical use and provides comprehensive genetic alteration data.

Phase III, Multicenter, Randomized Trial of Maintenance Chemotherapy Versus Observation in Patients With Metastatic Breast Cancer After Achieving Disease Control With Six Cycles of Gemcitabine Plus Paclitaxel As First-Line Chemotherapy: KCSG-BR07-02

PURPOSE The primary purpose of our study was to evaluate whether maintenance chemotherapy with paclitaxel/gemcitabine (PG) was superior to observation in improving progression-free survival (PFS) in patients with metastatic breast cancer (MBC) who achieved disease control with an initial six cycles of PG as their first-line treatment. PATIENTS AND METHODS The study was a prospective, randomized, multicenter, phase III trial. Patients MBC with who achieved disease control after six cycles of PG chemotherapy were randomly assigned to maintenance chemotherapy or observation until progression. RESULTS Of 324 patients from 10 centers enrolled, 231 patients with MBC exhibited disease control (complete response + partial response + stable disease) with first-line PG and were randomly assigned to maintenance chemotherapy (n = 116) or observation (n = 115). The median age was 48 years (range, 28 to 76 years), median follow-up was 33 months, and median number of chemotherapy cycles in the maintenance group after random assignment was six. The median PFS time after random assignment was longer in the maintenance group than in the observation group (7.5 v 3.8 months, respectively; P = .026). The median overall survival (OS) time was longer in the maintenance group than in the observation group (32.3 v 23.5 months, respectively; P = .047). The rate of grade 3 or higher neutropenia after random assignment was higher in the maintenance group than in the observation group (61% v 0.9%, respectively; P < .001). CONCLUSION In patients with MBC who achieved disease control with an initial six cycles of PG chemotherapy, maintenance PG chemotherapy resulted in better PFS and OS compared with observation.

RNA editing in RHOQ promotes invasion potential in colorectal cancer

Novel A-to-I RNA editing in the coding sequence of RHOQ leads to an amino acid substitution that promotes invasion in colorectal cancer.

Reduced Dose Intensity FOLFOX-4 as First Line Palliative Chemotherapy in Elderly Patients with Advanced Colorectal Cancer

To evaluate the toxicity and efficacy of a reduced dose intensity (mini-) FOLFOX-4 regimen as a first-line palliative chemotherapy in elderly patients (≥70 yr of age) with advanced colorectal cancer, data from prospective databases at Seoul National University Bundang Hospital and Seoul Municipal Boramae Hospital were analyzed. A total of 20 patients were enrolled between January 2001 and August 2004, and were treated with oxaliplatin 65 mg/m2 on day 1, and with 2-hr infusions of leucovorin 150 mg/m2 followed by a 5-FU bolus (300 mg/m2) and 22-hr continuous infusions (450 mg/m2) for 2 consecutive days every 2 weeks until progression, unacceptable toxicity or patient refusal. Sixteen patients were evaluable for response with an overall response rate of 43.8%. Median progression-free survival was 4.8 months (95% CI: 3.0-6.7) and overall survival was 13.5 months (95% CI: 11.1-16.0). The main side effects were anemia and neutropenia, which were observed in 20.8% and 17.7%, respectively, of the total cycles administered. There were no grade 4 toxicities and only one patient suffered from febrile neutropenia. No grade 3 toxicities occurred except for anemia (5.2%) and vomiting (1.0%). In conclusion, the mini-FOLFOX-4 regimen was found to be well tolerated with acceptable toxicity, and to provide a benefit for elderly patients with colorectal cancer.

Body mass index is not associated with treatment outcomes of breast cancer patients receiving neoadjuvant chemotherapy: korean data.

Purpose The effects of body mass index on pathologic complete response and survival have not been reported in Korean patients with breast cancer. The purpose of this study was to evaluate the predictive or prognostic value of obesity in breast cancer receiving neoadjuvant chemotherapy. Methods A total of 438 stage II or III breast cancer patients treated with neoadjuvant chemotherapy were enrolled and analyzed retrospectively. Results In the study, 319 patients (72.8%) were normal weight, 100 patients (22.8%) were overweight, and 19 patients (4.3%) were obese. Baseline clinicopathologic characteristics were not different among the groups, except for age. There were no differences in pathologic complete response rate between the groups (9.7% in normal weight, 10.0% in overweight, 5.3% in obese; p=0.804). Neither overweight nor obese patients showed a significant difference in relapse-free survival compared to normal weight patients (p=0.523 and p=0.931, respectively). Also, no significant difference in overall survival (p=0.520 and p=0.864, respectively) was observed. Conclusion Obesity or higher body mass index was not significantly associated with pathologic complete response and survival in Korean patients with breast cancer who received neoadjuvant chemotherapy. Our results suggest that the prognostic impact of body mass index is different from that of Western patients.

Association between mutations of critical pathway genes and survival outcomes according to the tumor location in colorectal cancer

Colorectal cancer (CRC) develops through the alteration of several critical pathways. This study was aimed at evaluating the influence of critical pathways on survival outcomes for patients with CRC.

Distinct clinical outcomes of two CIMP-positive colorectal cancer subtypes based on a revised CIMP classification system

Background:Colorectal cancer (CRC) is a heterogeneous disease in terms of molecular carcinogenic pathways. Based on recent findings regarding the multiple serrated neoplasia pathway, we revised an eight-marker panel for a new CIMP classification system.Methods:1370 patients who received surgical resection for CRCs were classified into three CIMP subtypes (CIMP-N: 0–4 methylated markers, CIMP-P1: 5–6 methylated markers and CIMP-P2: 7–8 methylated markers). Our findings were validated in a separate set of high-risk stage II or stage III CRCs receiving adjuvant fluoropyrimidine plus oxaliplatin (n=950).Results:A total of 1287/62/21 CRCs cases were classified as CIMP-N/CIMP-P1/CIMP-P2, respectively. CIMP-N showed male predominance, distal location, lower T, N category and devoid of BRAF mutation, microsatellite instability (MSI) and MLH1 methylation. CIMP-P1 showed female predominance, proximal location, advanced TNM stage, mild decrease of CK20 and CDX2 expression, mild increase of CK7 expression, BRAF mutation, MSI and MLH1 methylation. CIMP-P2 showed older age, female predominance, proximal location, advanced T category, markedly reduced CK20 and CDX2 expression, rare KRAS mutation, high frequency of CK7 expression, BRAF mutation, MSI and MLH1 methylation. CIMP-N showed better 5-year cancer-specific survival (CSS; HR=0.47; 95% CI: 0.28–0.78) in discovery set and better 5-year relapse-free survival (RFS; HR=0.50; 95% CI: 0.29–0.88) in validation set compared with CIMP-P1. CIMP-P2 showed marginally better 5-year CSS (HR=0.28, 95% CI: 0.07–1.22) in discovery set and marginally better 5-year RFS (HR=0.21, 95% CI: 0.05–0.92) in validation set compared with CIMP-P1.Conclusions:CIMP subtypes classified using our revised system showed different clinical outcomes, demonstrating the heterogeneity of multiple serrated precursors of CIMP-positive CRCs.

Safety and antitumor activity of the anti–PD-1 antibody pembrolizumab in patients with advanced colorectal carcinoma

Background Colorectal cancers (CRCs) expressing programmed death ligand 1 (PD-L1) have poor prognosis. In the multicohort KEYNOTE-028 trial, the anti–PD-1 antibody pembrolizumab was evaluated in 20 PD-L1–positive advanced solid tumors. Herein, we report results for the advanced CRC cohort. Methods Patients with advanced, treatment-resistant PD-L1–positive carcinoma of the colon or rectum were enrolled, regardless of microsatellite instability (MSI) status. Pembrolizumab 10 mg/kg was administered every 2 weeks for up to 2 years or until disease progression/unacceptable toxicity. Response was assessed every 8 weeks for the first 6 months and every 12 weeks thereafter. Primary end points were safety and overall response rate by investigator review per Response Evaluation Criteria in Solid Tumors version 1.1. Data cutoff was June 20, 2016. Results Of 137 patients with CRC and samples evaluable for PD-L1 expression, 33 (24%) had PD-L1–positive tumors, of which 23 were enrolled. Median follow-up was 5.3 months, and 8 patients (35%) reported treatment-related adverse events (AEs), most commonly fatigue (n = 3, 13%), stomatitis (n = 2, 9%), and asthenia (n = 2, 9%). One patient (4%) experienced grade 4 treatment-related increased blood bilirubin. No grade 3 AEs, discontinuations, or deaths were attributed to treatment. Most patients (n = 15, 65%) experienced progressive disease. One partial response occurred in a patient (4%) with MSI-high CRC. Conclusion Pembrolizumab demonstrated a favorable safety profile in advanced PD-L1–positive CRC. Antitumor activity was observed in a single patient with MSI-high CRC, warranting further evaluation in this patient population. (Clinicaltrials.gov registration: NCT02054806)

Efficacy of Exemestane in Korean Patients with Metastatic Breast Cancer after Failure of Nonsteroidal Aromatase Inhibitors

Purpose Exemestane has shown good efficacy and tolerability in postmenopausal women with hormone receptor-positive metastatic breast cancer. However, clinical outcomes in Korean patients have not yet been reported. Methods Data on 112 postmenopausal women with metastatic breast cancer were obtained retrospectively. Clinicopathological characteristics and treatment history were extracted from medical records. All patients received 25 mg exemestane daily until objective disease progression. Progression-free survival (PFS) was the primary endpoint, and secondary endpoints were overall survival (OS), objective response rate (ORR), and clinical benefit rate (CBR=complete response+partial response+stable disease for 6 months). Results The median age of the subjects was 55 years (range, 28-76 years). Exemestane treatment resulted in a median PFS of 5.7 months (95% confidence interval [CI], 4.4-7.0 months) and median OS of 21.9 months (95% CI, 13.6-30.3 months). ORR was 6.4% and CBR was 46.4% for the 110 patients with evaluable lesions. Symptomatic visceral disease was independently associated with shorter PFS (hazard ratio, 3.611; 95% CI, 1.904-6.848; p<0.001), compared with bone-dominant disease in a multivariate analysis of PFS after adjusting for age, hormone receptor, human epidermal growth factor receptor 2, Ki-67 status, dominant metastasis site, and sensitivity to nonsteroidal aromatase inhibitor (AI) treatment. Sensitivity to previous nonsteroidal AI treatment was not associated with PFS, suggesting no cross-resistance between exemestane and nonsteroidal AIs. Conclusion Exemestane was effective in postmenopausal Korean women with hormone receptor-positive metastatic breast cancer who failed previous nonsteroidal AI treatment.

Abstract 2427: Overexpression of insulin/IGF hybrid receptor as predictive biomarker of response to a humanized anti-insulin like growth factor-I receptor monoclonal antibody (CP751,871) in gastric and hepatocellular carcinoma cells

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Insulin-like Growth factor I receptor (IGF-IR) is highly expressed in many human cancers and plays a major role in proliferation, survival, and metastasis. Accordingly, abundant IGF-1R targeting drugs, especially monoclonal antibody drugs, have been focused and developed due to their safety and efficacy. In order to define biomarkers correlating with the drug sensitivity, we screened 10 gastric and 10 hepatocellular cancer cell lines, for in vitro response to CP-751,871, anti-insulin like growth factor type 1 receptor antibody. Our results show that CP-751,871 inhibits IGF-1 ligand-dependent IGF-1R phosphorylation and downstream signaling of the two major IGF-1R pathways, mitogen-activated protein kinase and phosphatidylinositol 3′-kinase/AKt. Moreover, long-term exposure to CP-751,871 also caused to decrease phospho-stat 3 as well as phospho-Akt level and induced G1 phase cell cycle arrest in dose-dependent manner preferentially in the sensitive cells. Surprisingly, among these 20 cell lines, cells with IGF-IR and insulin receptor (IR) were significantly inhibited by CP-751,871 compared to cells with IGF-IR or IR overexpression only. Considering their highly homologous structure, we thereby determined if the effect of CP-751,871 had relevance to the level of IR/IGF1R hybrid receptors through co-immunoprecipitation with either CP-751,871 or IGF1R antibody. Its immunoblot analysis revealed that not only did sensitive cell lines, such as SNU719, SNU368, and HepG2, show relatively higher levels of IR/IGF1R hybrid, but also superior ability of CP-751,871 to recognize their IR/IGF1R heterodimer complexes. Furthermore, we could observe that the hybrid forms were recruited by IGF1 ligands but this IGF-I ligand dependent formation was blockaded by CP-751,871. Lastly, the treatment of these sensitive cell lines with CP-751,871 caused dimer dissociation. Therefore, our data suggest that the antiproliferative effect by CP-751,871 requires the co-expression of IGF-1R and IR and may be related with the expression level of hybrid Insulin/IGF-1 receptors in gastric and hepatocellular carcinoma cell lines. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2427.