IntroductionEpirubicin is a common adjuvant treatment for breast cancer. It is mainly eliminated after glucuronidation through uridine diphosphate-glucuronosyltransferase 2B7 (UGT2B7). The present study aimed to describe the impact of the UGT2B7His268Tyr polymorphism on invasive disease-free survival in breast cancer patients after epirubicin treatment.MethodsThis is a pharmacogenetic study based on samples collected from 745 breast cancer patients of the Austrian Tumor of breast tissue: Incidence, Genetics, and Environmental Risk factors (TIGER) cohort who did not present metastases at baseline. This cohort included 205 women with epirubicin-based combination chemotherapy, 113 patients having received chemotherapy without epirubicin and 427 patients having received no chemotherapy at all. Of the epirubicin-treated subgroup, 120 were subsequently treated with tamoxifen. For all women UGT2B7His268Tyr was genotyped. Invasive disease-free survival was assessed using Kaplan-Meier and Cox's proportional hazard regression analysis.ResultsAmong the 205 epirubicin-treated patients, carriers of two UGT2B7268Tyr alleles had a mean invasive disease-free survival of 8.6 (95% confidence interval (CI) 7.9 to 9.3) years as compared to 7.5 (95% CI 6.9 to 8.0) years in carriers of at least one UGT2B7268His allele (adjusted hazard ratio (HR) = 2.64 (95% CI 1.22 to 5.71); P = 0.014). In addition, the impact of the UGT2B7His268Tyr polymorphism became even more pronounced in patients subsequently treated with tamoxifen (adjusted HR = 5.22 (95% CI 1.67 to 26.04); P = 0.015) whereas no such difference in invasive disease-free survival was observed in patients not receiving epirubicin.ConclusionsBreast cancer patients carrying the UGT2B7268Tyr/Tyr genotype may benefit most from adjuvant epirubicin-based chemotherapy. These results warrant confirmation in further studies.

While earlier data on CYP2D6 and tamoxifen excluded women with prior chemotherapy, the present analysis suggests that CYP2D6*4 genotype might be particularly crucial in this group of high-risk patients. Key limitations are restriction to the CYP2D6*4 allele and missing data of comedication.

BACKGROUND:Gene expression profiling has the potential to offer consistent, objective diagnostic test results once a standardized protocol has been established. We investigated the robustness, precision, and reproducibility of microarray technology.

Tamoxifen is a mainstay in the treatment of hormone-receptor sensitive breast cancer. To be effective, it needs conversion into 4-hydroxy-tamoxifen and endoxifen. The key enzyme involved is encoded by the gene CYP2D6 of which several, sometimes population-specific alleles are known. Corresponding enzyme variants may result in poor, intermediate, and extensive metabolization and therefore different steady-state plasma levels of active metabolites. Those are hypothesized to be linked to clinical outcomes of tamoxifen therapy. However, a wealth of mostly retrospective cohort studies came up with conflicting results. Appraisal of these studies is difficult and a metaanalysis impossible due to heterogeneity of patient populations, disease factors, treatment modalities, and measured outcomes. As standardization would not overcome intrinsic limitations of retrospective analyses, prospective trials comparing genotype-guided versus unsighted tamoxifen treatment are required to prove whether routine CYP2D6 genotyping is clinically effective and cost-effective.

Gene expression profiling has the potential to offer consistent objective diagnostic test results once a standardized protocol is established. We investigated the robustness, precision, and reproducibility of this technology and present data that complements the Microarray Innovations in LEukemia study (MILE study). In four laboratories, located in Germany (D), Austria (A), and Switzerland (CH) (DACH study), replicates of 112 patient samples were analyzed using the AmpliChip Leukemia research test. Patient samples were centrally collected and diagnosed in daily routine at the Munich Leukemia Laboratory and represented 8 distinct classes of acute and chronic leukemias, with non-leukemia as control group. After purification of the mononuclear cells by Ficoll density centrifugation, 4 × 5 million cells were frozen in lysis buffer and stored at −80°C. Equipped with identical instruments, software, and reagents, study operators were trained on the microarray sample preparation protocol using total RNA from commercially available cell lines. Upon receipt of the frozen lysates each of the four laboratories purified the total RNA from the 112 technical quadruplicates. 99.3% (445/448) of the sample preparations were successfully performed. On average, 8.4 μg, 7.2 μg, 7.4 μg, or 7.5 μg of total RNA, respectively, were isolated from the mononuclear cells from the four laboratories. In three samples less than 1.0 μg of total RNA was obtained and thus the preparation failed. Bland-Altman plots of agreement showed that any two centers were unlikely to have more than an 8.3 μg difference in yield of total RNA from the same sample. On average there was between 0.1 μg to 1.2 μg difference in total RNA yield from the same sample. Further processing of the 445 samples resulted in 437 (98.2%) successfully performed in vitro transcription reactions, i.e. obtained cRNA yield of >8.0 μg. On average there was between 0.4 μg to 7.4 μg difference in cRNA yield from the same sample. After hybridization to microarrays on average, 46.1%, 48.6%, 46.5%, and 47.3% of probe sets were detected as present with mean scaling factors of 4.3, 2.9, 3.9, and 3.7, respectively. The mean values and standard deviations of distributions of the coefficient of variation (CV) within each site over all the probe sets of the quantile normalized signals on the chip were 27.2% (StdDev: 12.3%), 27.0% (StdDev: 12.3%), 27.3% (StdDev: 12.3%), 26.9% (StdDev: 12.4%), respectively. Furthermore, in unsupervised hierarchical cluster and principal component analyses replicates from the same patient always clustered closely together, with no indications of association between gene expression profiles due to different operators or laboratories. In conclusion, we demonstrated that microarray analysis can be performed with remarkably high inter-laboratory reproducibility and with comparable quality and high technical precision across laboratories.