Daniela Dornelles Rosa

Endoxifen levels and its association with CYP2D6 genotype and phenotype: evaluation of a southern Brazilian population under tamoxifen pharmacotherapy.

Background: An association between CYP2D6 variation and clinical outcomes among women with breast cancer treated with tamoxifen (TAM) has been demonstrated, such that the presence of 2 functional CYP2D6 alleles was associated with better clinical outcomes. This association is mainly due to the CYP2D6-mediated hydroxylation of N-desmethyltamoxifen (NDT) to yield endoxifen (EDF), which because of its high antiestrogenic potency, is mainly responsible for the therapeutic efficacy of TAM. The aim of this study was to evaluate the relation of CYP2D6 genotyping and phenotyping with EDF levels and [NDT]/[EDF] metabolic ratio in breast cancer patients from South of Brazil under TAM therapy. Methods: Trough blood samples were collected from 97 patients. CYP2D6 genotyping was performed with a luminex assay and calculation of genotypic activity scores. Tamoxifen and metabolites EDF, NDT, and 4-hydroxy-TAM were measured in plasma by high performance liquid chromatography with photo diode array detector. CYP2D6 phenotyping was performed by the determination of dextromethorphan (DMT) and dextrorphan (DTF) by high-performance liquid chromatography with fluorescence detection at plasma collected 3 hours after oral administration of 33 mg of DMF. Phenotypes were given according to [DMT]/[DTF] metabolic ratio. Results: CYP2D6 genotyping indicated a prevalence of 4.1% poor metabolizer, 4.1% intermediate metabolizer, 49.5% extensive metabolizer slow activity, 39.2% extensive metabolizer fast activity, and 3.1% ultrarapid metabolizer. Genotype (genotypic activity scores) was significantly correlated with phenotype ([DMT]/[DTF]), with a moderate association (rs = −0.463; P < 0.001). Median plasma concentrations (nanograms per milliliter; N = 97) were TAM 57.17; 4-hydroxy-TAM 1.01; EDF 6.21; NDT 125.50. EDF levels were lower in poor metabolizers than that in extensive metabolizers (P < 0.05). Phenotype showed stronger, but still moderate, association with EDF and [NDT]/[EDF] than genotype (r = −0.507, r = 0.625, P < 0.001 versus r = 0.356, r = 0.516, P < 0.01). Phenotype accounted for 26% of the variability in EDF levels and 38% of [NDT]/[EDF], whereas genotype accounted for 12% and 27%, respectively. Conclusions: CYP2D6 genotyping and/or phenotyping could not fully predict EDF concentrations. Monitoring EDF itself could be considered during TAM therapy.

Sensitive HPLC–PDA determination of tamoxifen and its metabolites N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in human plasma

A highly sensitive HPLC-UV method for the simultaneous determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in human plasma samples was developed and validated. The method employs a two step liquid-liquid extraction and a reversed phase separation on a Hypersil Gold(®) C18 column (150mm×4.6mm, 5μm) with isocratic elution. Mobile phase was a mixture of triethylammonium phosphate buffer 5mM pH 3.3 and acetonitrile (57:43, v/v). Total analytical run time was 16min. Precision assays showed CV % lower than 10.53% and accuracy in the range of 93.0-104.2%. The lower limits of quantification (0.75-8.5ngml(-1)) are adequate to measure clinically relevant concentrations in plasma samples. The method was successfully applied to 110 clinical plasma samples. Median plasma levels and interquartile range were: tamoxifen 55.77ngml(-1) (38.42-83.69ngml(-1)), N-desmethyltamoxifen 124.83ngml(-1) (86.81-204.80ngml(-1)), 4-hydroxytamoxifen 1.09ngml(-1) (0.76-1.53ngml(-1)) and endoxifen 6.18ngml(-1) (4.17-8.22ngml(-1)). The procedure has adequate analytical performance and can be employed in therapeutic drug monitoring of tamoxifen or pharmacokinetics studies.

Association of adipokines and adhesion molecules with indicators of obesity in women undergoing mammography screening

BackgroundThe soluble cell adhesion molecules and adipokines are elevated in patients with obesity, hypertension, type 2 diabetes mellitus, breast cancer and atherosclerosis.ObjectiveTo investigate the relationship between anthropometric profile, dietary intake, lipid profile and fasting glycemia with serum levels of adipokines (adiponectin and PAI-1) and adhesion molecules (ICAM-1 and VCAM-1) in women without breast cancer undergoing routine mammographic screening.DesignTransversal study.SubjectsOne hundred and forty-five women over 40-years old participated in this study.ResultsIn 39.3% of cases the BMI was above 30 kg/m2; 46.9% had hypertension, 14.5% had type 2 Diabetes Mellitus, 31.7% had dyslipidemia and 88.3% presented a waist-to-hip ratio ≥ 0.8. A linear correlation was found between serum levels of PAI-1 and triglycerides, between serum levels of PAI-1 and WHR and between serum levels of VCAM-1 and BMI.ConclusionWe found a high prevalence of obesity and metabolic syndrome. PAI-1 and VCAM-1 levels were correlated with clinical indicators of obesity and overweight.

CYP3A4*22 is related to increased plasma levels of 4-hydroxytamoxifen and partially compensates for reduced CYP2D6 activation of tamoxifen.

AIM To evaluate the impact of CYP3A4*22 in the formation of endoxifen (EDF) and hydroxytamoxifen (HTF), under different CYP2D6 genotypic backgrounds. MATERIALS & METHODS 178 patients were enrolled in the study. CYP2D6 and CYP3A4 genotyping and tamoxifen (TAM) and metabolites quantification were performed. RESULTS EDF concentrations were lower in poor (2.77 ng ml(-1)) and CYP2D6 intermediate metabolizers (5.84 ng ml(-1)), comparing to functional group (EM-F) (10.67 ng ml(-1), p < 0.001). HTF and TAM levels were respectively 47 and 53% higher in CYP3A4*22 carriers compared with *1/*1 patients in the whole group. Patients with impaired CYP2D6 metabolism and carriers of CYP3A4*22 had EDF levels comparable to CYP2D6 EM-F group (9.06 and 10.67 ng ml(-1), p = 0.247). CONCLUSION The presence of CYP3A4*22 might compensate the reduction of EDF concentrations related to CYP2D6 inactivity, especially due to increased HTF concentrations.

Accuracy of telomerase in estimating breast cancer risk: A systematic review and meta-analysis

OBJECTIVE To determine the accuracy of telomerase activity in predicting a higher risk for breast cancer. STUDY DESIGN A quantitative systematic review was performed. Studies that detected telomerase activities in breast tissue were included. RESULTS Twenty-five primary studies were analyzed, which included 2395 breast lesions. The proportion of breast cancer was 60.8%. Eighty-two percent (1193/1455) of breast cancer cases and 18% (169/940) of benign lesions cases were positive for telomerase activity. For breast cancer vs benign or normal breast tissue, the pooled likelihood ratio for the presence of telomerase activity was 4.5 (95% confidence interval [CI], 3.1-6.5) and the post-test probability was 88% (95% CI, 83-91). For breast cancer vs benign or normal tissue, the area under the summary receiver operating characteristic (SROC) curve was 0.89 with the Q* point value of 0.82. CONCLUSION Our systematic review showed that telomerase activity was significantly present in breast cancer when compared with normal breast tissue or benign breast lesions.

Effects of lifestyle modification after breast cancer treatment: a systematic review protocol

BackgroundThere is no consensus in the literature regarding the effectiveness of lifestyle modification interventions, including recommendations about specific diet or exercise program for patients with breast cancer. Diet interventions and regular physical activity may reduce the risk of breast cancer and its recurrence. The primary aim of our study is to evaluate the effects of different lifestyle modification interventions (diet and physical activity) in the survival of patients with stages I to III breast cancer after treatment.Methods/designThis review will be conducted according to the Cochrane Handbook for Systematic Reviews of Intervention and will be reported following the PRISMA statement recommendations. CENTRAL, MEDLINE and EMBASE databases will be searched for peer-reviewed literature. Randomized controlled trials of diet, exercise, or both, compared with usual care, after treatment of breast cancer stage I to III will be included in the systematic review. Two authors will independently screen titles and abstracts of studies for potential eligibility. Data will be combined using random-effect meta-analysis models with restricted maximum-likelihood as variance estimator, and will be presented as relative risk or standardized mean difference with 95% CI. The quality of evidence will be assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework and summary of findings tables will be presented for patient important outcomes.DiscussionOur study may improve the current understanding of the role that lifestyle-modifiable factors can play in saving or prolonging the lives of women who have been treated for breast cancer, and also on modifying their quality of life.Systematic review registrationThe review has been registered with PROSPERO (registration number CRD42014008743).

Development, validation and clinical application of a HPLC-FL method for CYP2D6 phenotyping in South Brazilian breast cancer patients

OBJECTIVE To develop and validate a method for determination of dextromethorphan (DMT) and dextrorphan (DTP) in plasma samples using HPLC-FL and to apply it to CYP2D6 phenotyping of a population from the South of Brazil. METHODS Samples were prepared by hydrolysis and liquid-liquid extraction. Analysis was conducted in a reversed phase column, with isocratic elution and fluorescence detection. One hundred and forty patients being treated with tamoxifen were given 30 mg of dextromethorphan and their CYP2D6 phenotypes were determined on the basis of [DMT]/[DTP] metabolic ratios in plasma samples collected after 3h. RESULTS Total chromatography running time was 12 min. Precision (CV%) was below 9.7% and accuracy was between 92.1 and 106.9%. The lower limits of quantification were 1 ng mL(-1) for DMT and 10 ng mL(-1) for DTP. Mean extraction yield of analytes was 86.6%. Mean age of patients was 55.7 years. Phenotype frequencies were as follows: 7.1% poor metabolizers, 13.6% intermediate metabolizers, 77.1% extensive metabolizers and 2.1 ultra-rapid metabolizers. Metabolic ratios for patients on strong (n=11) and weak (n=16) CYP2D6 activity inhibitors were different from each other and also different from ratios for patients not taking enzyme inhibitors (n=113). CONCLUSIONS A sensitive method for determination of dextromethorphan and its metabolite in plasma samples was developed and successfully applied, providing evidence of the impact that CYP2D6 inhibitors have on the enzymes metabolic capacity.

Association of Axillarty Web Syndrome and Body Mass Index

INTRODUCTION: Breast cancer incidence has been increasing in Brazil and is now the leading cause of cancer death among women. Axillary web syndrome (AWS) is may occur in patients who underwent surgery for breast cancer with an axillary approach, either sentinel lymph node (SLN) biopsy or axillary dissection (AD). It usually appears 8 to 15 days after axillary surgery and is characterized by cords of subcutaneous tissue that extend from the axilla to the medial arm, sometimes reaching also the thumb. Few reports have been published describing this entity, that may cause pain and limitation of homolateral movements, especially shoulder abduction. Patients with a body mass index (BMI) greater than 25 seems to have a trend not to form cords, probably because cushions of fat may favor the reabsorption of lymph. MATERIALS AND METHODS: We evaluated patients with breast cancer treated in a referral center in Porto Alegre - RS from November 2010 to May 2012. Data from patients with the diagnosis of AWS were extracted from a large database. We compared shoulder range motion with BMI in these patients. RESULTS: We evaluated 54 patients with AWS. The mean age was 50. 7 years and the mean BMI was 23. 9kg/m2. Patients had stage IA to IIIC breast cancer. The web syndrome appeared to be a major cause of limitation in shoulder range of motion. Shoulder abduction was limited to 90 degrees or less in 21 (38%) of all the AWS patients. Mean BMI of patients who lost 50% or more of shoulder abduction was similar to those who lost less than 50% (23. 9kg/m2 versus 24. 3kg/m2 respectively). Mean BMI of patients who who lost 50% or more of shoulder flexion was similar to those who lost less than 50% (24. 9kg/m2 versus 23. 7kg/m2 respectively). DISCUSSION AND CONCLUSION: Axillary web syndrome is a definite clinical entity that tends to develop after axillary surgery for breast cancer. It is associated with pain and limitation of shoulder movement. We did not find any association between limitations in shoulder range motion according with BMI.