Keun Seok Lee

Clinical Implications of CYP2D6 Genotypes Predictive of Tamoxifen Pharmacokinetics in Metastatic Breast Cancer

PURPOSE The CYP3A and CYP2D6 enzymes play a major role in converting tamoxifen to its active metabolites. CYP3A is a highly inducible enzyme, regulated mainly by pregnane X receptor (PXR). This study assessed the association between genetic polymorphisms of CYP2D6 and PXR, and tamoxifen pharmacokinetics (PK) and clinical outcomes in patients with breast cancer. PATIENTS AND METHODS Plasma concentrations of tamoxifen and its metabolites were measured. Common alleles of CYP2D6 and PXR were identified in 202 patients treated with tamoxifen 20 mg daily for more than 8 weeks. Twelve of the 202 patients and an additional nine patients with metastatic breast cancer receiving tamoxifen were assessed for clinical outcome in correlation with genotypes. RESULTS Patients carrying CYP2D6*10/*10 (n = 49) demonstrated significantly lower steady-state plasma concentrations of 4-hydroxy-N-desmethyltamoxifen and 4-hydroxytamoxifen than did those with other genotypes (n = 153; 4-hydroxy-N-desmethyltamoxifen: 7.9 v 18.9 ng/mL, P < .0001; 4-hydroxytamoxifen: 1.5 v 2.6 ng/mL, P < .0001), whereas no difference by PXR genotypes was found. CYP2D6*10/*10 was significantly more frequent among nonresponders with MBC (100% v 50%, P = .0186). In Cox proportional hazard analysis, CYP2D6 genotype and number of disease sites were significant factors affecting time to progression (TTP). The median TTP for patients receiving tamoxifen was shorter in those carrying CYP2D6*10/*10 than for others (5.0 v 21.8 months, P = .0032) CONCLUSION CYP2D6*10/*10 is associated with lower steady-state plasma concentrations of active tamoxifen metabolites, which could possibly influence the clinical outcome by tamoxifen in Asian breast cancer patients.

Fatty fish and fish omega-3 fatty acid intakes decrease the breast cancer risk: a case-control study

BackgroundAlthough it is believed that fish ω-3 fatty acids may decrease breast cancer risk, epidemiological evidence has been inconclusive. This study examined the association between fish and fish ω-3 fatty acids intake with the risk of breast cancer in a case-control study of Korean women.MethodsWe recruited 358 incident breast cancer patients and 360 controls with no history of malignant neoplasm from the National Cancer Center Hospital between July 2007 and April 2008. The study participants were given a 103-item food intake frequency questionnaire to determine their dietary consumption of fish (fatty and lean fish) and ω-3 fatty acids derived from fish (eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA)).ResultsUsing a multivariate logistic regression model, high intake of fatty fish was associated with a reduced risk for breast cancer in both pre- and postmenopausal women (OR [95% CI] for highest vs. lowest intake quartiles, p for trend: 0.19 [0.08 to 0.45], p < 0.001 for premenopausal women, 0.27 [0.11 to 0.66], p = 0.005 for postmenopausal women). Similarly, reductions in breast cancer risk were observed among postmenopausal subjects who consumed more than 0.101 g of EPA (OR [95% CI]: 0.38 [0.15 to 0.96]) and 0.213 g of DHA (OR [95% CI]: 0.32 [0.13 to 0.82]) from fish per day compared to the reference group who consumed less than 0.014 g of EPA and 0.037 g of DHA per day. Among premenopausal women, there was a significant reduction in breast cancer risk for the highest intake quartiles of ω-3 fatty acids (ORs [95% CI]: 0.46 [0.22 to 0.96]), compared to the reference group who consumed the lowest quartile of intake.ConclusionThese results suggest that high consumption of fatty fish is associated with a reduced risk for breast cancer, and that the intake of ω-3 fatty acids from fish is inversely associated with postmenopausal breast cancer risk.

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.

Phase II Parallel Group Study Showing Comparable Efficacy Between Premenopausal Metastatic Breast Cancer Patients Treated With Letrozole Plus Goserelin and Postmenopausal Patients Treated With Letrozole Alone As First-Line Hormone Therapy

PURPOSE Goserelin and letrozole in premenopausal patients can result in clinical outcomes comparable to those obtained by letrozole alone in postmenopausal patients with metastatic breast cancer (MBC). PATIENTS AND METHODS A total of 73 patients with hormone-responsive MBC were included. Of those, 35 premenopausal patients received goserelin (3.6 mg subcutaneously every 28 days) plus letrozole (2.5 mg orally daily), and 38 postmenopausal patients received letrozole alone as their first-line endocrine therapy in a metastatic setting. RESULTS Baseline characteristics were similar in the two groups, except for a younger age (median, 41 v 53.5 years; P < .001) and a shorter disease-free interval (median, 1.8 v 3.3 years; P = .03) in the premenopausal group. Clinical benefit rates were comparable between the two groups (77% v 74%; P = .77). With the median follow-up of 27.4 months, there was no statistical difference in the median time to progression between the two groups (9.5 months [95% CI, 6.4 to 12.1 months] v 8.9 months [95% CI, 6.4 to 13.3 months]). In patients who did not receive bisphosphonate, letrozole +/- goserelin caused a greater loss of bone mineral density at 6 months compared with that of patients receiving bisphosphonate treatment (premenopausal group, -16.7% v 53.9%; P = .002 and postmenopausal group, -13.3% v 17.4%; P = .04 at the lumbar spine). CONCLUSION Clinical efficacies in premenopausal MBC patients with combined letrozole and goserelin therapy were comparable to those in postmenopausal patients treated with letrozole alone. Although letrozole +/- goserelin resulted in a modest increase in bone resorption, concurrent treatment with bisphosphonate could prevent bone loss at 6 months.

The invasive lobular carcinoma as a prototype luminal A breast cancer: A retrospective cohort study

BackgroundAlthough the invasive lobular carcinoma (ILC) is the second most frequent histologic subtype in Western countries, its incidence is much lower in Asia, and its characteristics are less well known.MethodsWe assessed the clinical characteristics and outcomes of 83 Korean patients (2.8%) with ILC for comparison with 2,833 (97.2%) with the invasive ductal carcinoma (IDC), including 1,088 (37.3%) with the luminal A subtype (LA-IDC).ResultsThe mean age of all patients was 48.2 years, with no significant differences among the groups. Compared to IDC, ILC showed a larger tumor size (≥T2, 59.8% vs. 38.8%, P = 0.001), a lower histologic grade (HG 1/2, 90.4% vs. 64.4%, P < 0.001), more frequent estrogen receptor positive (90.4% vs. 64.4%, P < 0.001), progesterone receptor positive (71.1% vs. 50.1%, P < 0.001) and HER2 negative (97.5% vs. 74.6%, P < 0.001) status, and lower Ki-67 expression (10.3% ± 10.6% vs. 20.6% ± 19.8%, P < 0.001), as well as being more likely to be of the luminal A subtype (91.4% vs. 51.2%, P < 0.001). Six (7.2%) ILC and 359 (12.7%) IDC patients developed disease recurrence, with a median follow-up of 56.4 (range 4.9-136.6) months. The outcome of ILC was close to LA-IDC (HR 0.77 for recurrence, 95% CI 0.31-1.90, P = 0.57; HR 0.75 for death, 95% CI 0.18-3.09, P = 0.70) and significantly better than for the non-LA-IDC (HR 1.69 for recurrence, 95% CI 1.23-2.33, P = 0.001; HR 1.50 for death, 95% CI 0.97-2.33, P = 0.07).ConclusionsILC, a rare histologic type of breast cancer in Korea, has distinctive clinicopathological characteristics similar to those of LA-IDC.

Prognostic Implications of Tumor-Infiltrating Lymphocytes in Association With Programmed Death Ligand 1 Expression in Early-Stage Breast Cancer.

BACKGROUND The immune system might influence breast cancer (BC) prognosis. However, the relationship between programmed death ligand 1 (PD-L1) and tumor-infiltrating lymphocyte (TIL) profiles remains unclear with respect to BC subtypes. PATIENTS AND METHODS We investigated the relationship between TIL profiles for CD8+ and forkhead box P3-positive (FOXP3+) and PD-L1 expression in primary tumor tissue using immunohistochemistry and the clinical outcomes in 2 patient cohorts at the National Cancer Center: 256 patients diagnosed with early-stage BC from January 2001 to December 2005 and 77 hormone receptor (HR)-negative BC patients diagnosed from January 2006 to December 2008. Clinical data were collected, including HR status, human epidermal growth factor receptor 2 expression, disease-free survival, and overall survival (OS). RESULTS The median patient age was 47 years (range, 28-78), and the median follow-up period was 9.8 years. Of the 333 patients, 186 (55.9%) had HR-positive and 125 (37.5%) had node-positive BC. We found a strong positive correlation between CD8+ TILs and FOXP3+ TILs (P < .001). CD8+ TILs were more abundant in tumors with low PD-L1 expression (P < .001), although no association was found between FOXP3+ TILs and PD-L1 expression. More CD8+ TILs were present in HR-negative than in HR-positive BC (P < .001), and PD-L1 expression was more frequent in HR-positive BC (P < .001). A greater number of CD8+ TILs (increase in quartile) was strongly associated with OS (hazard ratio, 0.61; 95% confidence interval, 0.39-0.95; P = .03) only in HR-negative BC when adjusted for various clinical factors. PD-L1 expression and FOXP3+ TILs did not exhibit such associations. CONCLUSION Higher CD8+ lymphocyte infiltration was related to lower PD-L1 expression and higher FOXP3+ TIL infiltration in BC. Higher CD8+ TIL expression was associated with prolonged survival only in those with HR-negative BC.

Methylation patterns of genes coding for drug-metabolizing enzymes in tamoxifen-resistant breast cancer tissues.

The biological mechanisms underlying resistance to tamoxifen are of considerable clinical significance. However, little is known about the correlation between tamoxifen resistance and methylation of genes related to drug-metabolizing enzymes. To address this issue, we examined the methylation pattern and expression of the selected genes coding for drug-metabolizing enzymes, including COMT, CYP1A1, CYP2D6, NAT1, and SULT1A1 in tamoxifen-resistant and control breast cancers. Bisulfite genomic sequencing and methylation-specific PCR were carried out to evaluate the methylation patterns of the five genes from control (n = 74) and tamoxifen-resistant tissues (n = 37) chosen by an age-matched sampling method. Also, end-point reverse transcriptase polymerase chain reaction (RT-PCR) and real-time RT-PCR were performed to determine RNA expression of the genes. Bisulfite genomic sequencing revealed methylation of the NAT1 gene in 25 of the control cancers (33.8%) and 23 of the resistant tumors (62.2%). Of the five genes, only NAT1 showed a significant lower methylation rate in the control group than in the resistant group (p = 0.004). No significant difference of the methylation rate was found in the other four genes including COMT, CYP1A1, CYP2D6, and SULT1A1 (p > 0.05). Furthermore, the expression rate of NAT1 mRNA was lower in the tumors from the resistant group than in control tumors (28.6% vs. 65.2%, p = 0.031). Real-time RT-PCR analysis demonstrated that the NAT1 gene was more down-regulated in resistant tissues than in control group (p = 0.023). Moreover, malignant cells from the resistant cases demonstrated a higher percentage of positive staining for Ki67 (p = 0.001) and cyclin D1 (p = 0.043) than those from the control group. Taken together, the higher methylation rate of the NAT1 gene is related to tamoxifen resistance, and this fact supports the hypothesis that hypermethylation of the NAT1 gene might affect the initiation of tamoxifen resistance.

Association of Polymorphisms and Haplotypes in the Insulin-Like Growth Factor 1 Receptor (IGF1R) Gene with the Risk of Breast Cancer in Korean Women

The insulin-like growth factor (IGF) signaling pathway plays an important role in cancer biology. The IGF 1 receptor (IGF1R) overexpression has been associated with a number of hematological neoplasias and solid tumors including breast cancer. However, molecular mechanism involving IGF1R in carcinogenic developments is clearly not known. We investigated the genetic variations across the IGF1R polymorphism and the risk of breast cancer risk in Korean women. A total of 1418 individuals comprising 1026 breast cancer cases and 392 age-matched controls of Korean were included for the analysis. Genomic DNA was extracted from whole blood and single nucleotide polymorphisms (SNPs) were analyzed on the GoldenGate Assay system by Illumina’s Custom Genetic Analysis service. SNPs were selected for linkage disequilibrium (LD) analysis by Haploview. We genotyped total 51 SNPs in the IGF1R gene and examined for association with breast cancer. All the SNPs investigated were in Hardy-Weinberg equilibrium. These SNPs tested were significantly associated with breast cancer risk, after correction for multiple comparisons by adjusting for age at diagnosis, BMI, age at menarche, and age at first parturition. Among 51 IGF1R SNPs, five intron located SNPs (rs8032477, rs7175052, rs12439557, rs11635251 and rs12916884) with homozygous genotype (variant genotype) were associated with decreased risk of breast cancer. Fisher’s combined p-value for the five SNPs was 0.00032. Three intron located SNPs with heterozygous genotypes also had decreased risk of breast cancer. Seven of the 51 IGF1R SNPs were in LD and in one haplotype block, and were likely to be associated with breast cancer risk. Overall, this case-control study demonstrates statistically significant associations between breast cancer risk and polymorphisms in IGF1R gene.

Concordant HER2 status between metastatic breast cancer cells in CSF and primary breast cancer tissue

It is not known whether the HER2 status of malignant CSF cells coincides with that of the original breast carcinoma cells. We investigated whether CSF cytology specimens were suitable to evaluate HER2 status by fluorescence in situ hybridization (FISH) in patient with leptomeningeal metastasis (LM). Both formalin-fixed paraffin-embedded (FFPE) breast cancer tissue and liquid based CSF cytology specimens were evaluated for HER2 status in 16 patients with LM. We evaluated HER2 gene amplification using FISH on destained CSF cytology slides containing a minimum of 20 malignant cells per slide, and compared these with the HER2 status by immunohistochemistry (IHC) or FISH in FFPE tissues. HER2 was considered positive when the HER2:CEP17 ratio was ≥2.0 or IHC 3+. Of 16 cases, four were HER2 positive and 12 were HER2 negative by FISH analysis in CSF cytology. All CSF-positive cases were HER2 positive by IHC in FFPE tissue. Of 12 HER2 FISH-negative cases in CSF cytology, 10 were HER2 negative (IHC 0 or 1+) and two were IHC 2+ in FFPE tissue. Two IHC 2+ cases had HER2:CEP17 ratios of 1.27 and 2.1, respectively, by FISH in FFPE tissue. As a result, the HER2 status concordance rate between metastatic breast cancer cells in CSF and FFPE primary tissue by IHC and FISH was very high. When CSF cytology specimens were appropriately prepared and had adequate cellularity without dry artifacts, the CSF cytology was suitable to evaluate HER2 status by FISH analysis in patients with LM.

Serum HER2 as a response indicator to various chemotherapeutic agents in tissue HER2 positive metastatic breast cancer.

PURPOSE The aim of study was to evaluate the usefulness of serum HER2 as a therapeutic response indicator in patients with HER2 positive metastatic breast cancer (MBC). MATERIALS AND METHODS The levels of serum HER2 and CA15.3 were assayed in 148 serial serum samples from 50 HER2 positive MBC patients at both the baseline and follow-ups. The changes in the levels of serum HER2 and CA15.3 in relation to the tumor responses to the various chemotherapy regimens were monitored. RESULTS The levels of serum HER2 and CA15.3 were elevated in 82% and 62% of tissue HER2 positive patients, respectively, prior to therapies, with the changes in both tumor markers showing statistical significance in relation to the tumor responses (p<0.01) in patients with elevated baseline serum markers. CONCLUSION The level of serum HER2 could be a valuable response indicator, not only for trastuzumab containing therapy, but also for other common MBC chemotherapeutic agents. Also, as it is more frequently elevated, the serum level of HER2 may also be a more useful tumor marker than CA15.3 in HER2 positive MBC.