Raymond Ng

Impact of CYP2D6, CYP3A5, CYP2C9 and CYP2C19 polymorphisms on tamoxifen pharmacokinetics in Asian breast cancer patients

AIM To investigate the impact of genetic polymorphisms in CYP2D6, CYP3A5, CYP2C9 and CYP2C19 on the pharmacokinetics of tamoxifen and its metabolites in Asian breast cancer patients. METHODS A total of 165 Asian breast cancer patients receiving 20 mg tamoxifen daily and 228 healthy Asian subjects (Chinese, Malay and Indian; n= 76 each) were recruited. The steady-state plasma concentrations of tamoxifen and its metabolites were quantified using high-performance liquid chromatography. The CYP2D6 polymorphisms were genotyped using the INFINITI™ CYP450 2D6I assay, while the polymorphisms in CYP3A5, CYP2C9 and CYP2C19 were determined via direct sequencing. RESULTS The polymorphisms, CYP2D6*5 and *10, were significantly associated with lower endoxifen and higher N-desmethyltamoxifen (NDM) concentrations. Patients who were *1/*1 carriers exhibited 2.4- to 2.6-fold higher endoxifen concentrations and 1.9- to 2.1-fold lower NDM concentrations than either *10/*10 or *5/*10 carriers (P < 0.001). Similarly, the endoxifen concentrations were found to be 1.8- to 2.6-times higher in *1/*5 or *1/*10 carriers compared with *10/*10 and *5/*10 carriers (P≤ 0.001). Similar relationships were observed between the CYP2D6 polymorphisms and metabolic ratios of tamoxifen and its metabolites. No significant associations were observed with regards to the polymorphisms in CYP3A5, CYP2C9 and CYP2C19. CONCLUSIONS The present study in Asian breast cancer patients showed that CYP2D6*5/*10 and *10/*10 genotypes are associated with significantly lower concentrations of the active metabolite of tamoxifen, endoxifen. Identifying such patients before the start of treatment may be useful in optimizing therapy with tamoxifen. The role of CYP3A5, CYP2C9 and CYP2C19 seem to be minor.

Association of proinflammatory cytokines and chemotherapy-associated cognitive impairment in breast cancer patients: a multi-centered, prospective, cohort study

This is one of the largest multicentered, cohort studies conducted to evaluate the proinflammatory biomarkers associated with cognitive impairment in breast cancer patients. While elevated interleukin (IL)-6 and IL-1β were observed in patients with poorer response speed performance and perceived cognitive disturbances, IL-4 may be protective against chemotherapy-associated cognitive impairment.

An economic analysis of the INTEREST trial, a randomized trial of docetaxel versus gefitinib as second-/third-line therapy in advanced non-small-cell lung cancer

BACKGROUND The INTEREST (IRESSA NSCLC Trial Evaluating Response and Survival against Taxotere) trial compared gefitinib with docetaxel (Taxotere) in pretreated advanced non-small-cell lung cancer (NSCLC). Noninferiority for overall survival was concluded. Gefitinib had a better toxicity profile and greater improvements in quality of life (QoL). We undertook a cost-consequence analysis to estimate the direct medical costs of gefitinib compared with docetaxel. PATIENTS AND METHODS Summary data from INTEREST were used to derive resource utilization and direct costs from treatment start until drug discontinuation. Costs for treatment, adverse events, outpatient visits and investigations were calculated. Mean total cost-per-patient-per-arm was determined, and incremental cost was calculated. Utility values were generated from Functional Assessment of Cancer Therapy - Lung scores and compared between arms. RESULTS Incremental mean overall cost per patient for gefitinib over docetaxel was CAD

Effects of Chemotherapy and Psychosocial Distress on Perceived Cognitive Disturbances in Asian Breast Cancer Patients

5161. Drug was the major contributor to overall cost in both arms. Longer mean duration of gefitinib therapy (134 versus 91 days) contributed to the incremental cost difference. The cost per 21-day cycle was similar in both arms (

The English and Chinese versions of the five-level EuroQoL Group's five-dimension questionnaire (EQ-5D) were valid and reliable and provided comparable scores in Asian breast cancer patients

1963 docetaxel,

Mapping the Functional Assessment of Cancer Therapy - Breast (FACT-B) to the 5-level EuroQoL group’s 5-dimension questionnaire (EQ-5D-5L) utility index in a Multi-ethnic Asian population

2095 gefitinib). CONCLUSION The modest increase in cost associated with gefitinib supports its use as an alternative to docetaxel as second-line treatment of advanced NSCLC, particularly given the improvements in QoL, patient preference for oral therapy and better toxicity profile with gefitinib.

Association of CYP2C19*2 and associated haplotypes with lower norendoxifen concentrations in tamoxifen-treated Asian breast cancer patients

Background: There is conflicting evidence on the effect of chemotherapy and psychosocial distress on perceived cognitive changes in cancer patients. Objective: To compare the severity of perceived cognitive disturbance in Asian breast cancer patients receiving chemotherapy and those not receiving chemotherapy, and identify clinical characteristics associated with perceived cognitive disturbances. Methods: A cross-sectional, observational study was conducted at the largest cancer center in Singapore. Breast cancer patients receiving chemotherapy and not receiving chemotherapy completed the Functional Assessment of Cancer Therapy–Cognitive Function (FACT-Cog), European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (QLQ-C30), and Beck Anxiety Inventory to assess their perceived cognitive functioning, health-related quality of life, and anxiety, respectively. Multiple regression was conducted to delineate the factors associated with perceived cognitive disturbances. Results: A total of 85 breast cancer patients receiving chemotherapy and 81 not receiving chemotherapy were recruited. Chemotherapy patients experienced more fatigue (QLQ-C30 fatigue scores: 33.3 vs 22.2 points; p = 0.005) and moderate-to-severe anxiety (21.9% vs 8.6%; p = 0.002) compared to non-chemotherapy patients. Non-chemotherapy patients reported better perceived cognitive functioning than those who received chemotherapy (FACT-Cog scores: 124 vs 110 points, respectively; p < 0.001). Chemotherapy and endocrine therapy were strongly associated with perceived cognitive disturbances (p < 0.001 and 0.021, respectively). The interacting effect between anxiety and fatigue was moderately associated with perceived cognitive disturbances (β = -0.29; p = 0.037). Conclusions: Chemotherapy and endocrine treatment were associated with significant cognitive disturbances among Asian breast cancer patients. Psychosocial factors could be used to identify cancer patients who are more susceptible to cognitive disturbances in the clinical setting.

ETV6 disruption does not predict indolent clinical behavior in secretory breast carcinoma.

ObjectiveTo examine the measurement properties of and comparability between the English and Chinese versions of the five-level EuroQoL Group’s five-dimension questionnaire (EQ-5D) in breast cancer patients in Singapore.MethodsThis is an observational study of 269 patients. Known-group validity and responsiveness of the EQ-5D utility index and visual analog scale (VAS) were assessed in relation to various clinical characteristics and longitudinal change in performance status, respectively. Convergent and divergent validity was examined by correlation coefficients between the EQ-5D and a breast cancer-specific instrument. Test–retest reliability was evaluated. The two language versions were compared by multiple regression analyses.ResultsFor both English and Chinese versions, the EQ-5D utility index and VAS demonstrated known-group validity and convergent and divergent validity, and presented sufficient test–retest reliability (intraclass correlation = 0.72 to 0.83). The English version was responsive to changes in performance status. The Chinese version was responsive to decline in performance status, but there was no conclusive evidence about its responsiveness to improvement in performance status. In the comparison analyses of the utility index and VAS between the two language versions, borderline results were obtained, and equivalence cannot be definitely confirmed.ConclusionThe five-level EQ-5D is valid, responsive, and reliable in assessing health outcome of breast cancer patients. The English and Chinese versions provide comparable measurement results.

Predictors of Hand-Foot Syndrome and Pyridoxine for Prevention of Capecitabine–Induced Hand-Foot Syndrome: A Randomized Clinical Trial

PurposeTo develop an algorithm for mapping the Functional Assessment of Cancer Therapy – Breast (FACT-B) to the 5-level EuroQoL Group’s 5-dimension questionnaire (EQ-5D-5L) utility index.MethodsA survey of 238 breast cancer patients in Singapore was conducted. Models using various regression methods with or without recognizing the upper boundary of utility values at 1 were fitted to predict the EQ-5D-5L utility index based on the five subscale scores of the FACT-B. Data from a follow-up survey of these patients were used to validate the results.ResultsA model that maps the physical, emotional, functional well-being and the breast cancer concerns subscales of the FACT-B to the EQ-5D-5L utility index was derived. The social well-being subscale was not associated to the utility index. Although theoretical assumptions may not be valid, ordinary least square outperformed other regression methods. The mean predicted utility index within each performance status level at follow-up deviated from the observed mean less than the minimally important difference of EQ-5D for cancer patients.ConclusionsThe mapping algorithm converts the FACT-B to the EQ-5D utility index. This enables oncologists, clinical researchers and policy makers to obtain a quantitative utility summary of a patient’s health status when only the FACT-B is assessed.

Measurement Properties of the Eight-Item Abbreviated Functional Assessment of Cancer Therapy—Breast Symptom Index and Comparison With Its 37-Item Parent Measure

AIM The aim was to examine the influence of CYP2C19 variants and associated haplotypes on the disposition of tamoxifen and its metabolites, particularly norendoxifen (NorEND), in Asian patients with breast cancer. METHODS Sixty-six CYP2C19 polymorphisms were identified in healthy Asians (n = 240), of which 14 were found to be tightly linked with CYP2C19*2, CYP2C19*3 and CYP2C19*17. These 17 SNPs were further genotyped in Asian breast cancer patients receiving tamoxifen (n = 201). Steady-state concentrations of tamoxifen and its metabolites were quantified using liquid chromatography–mass spectrometry. Non-parametric tests and regression methods were implemented to evaluate genotypic–phenotypic associations and haplotypic effects of the SNPs. RESULTS CYP2C19 functional polymorphisms and their linked SNPs were not significantly associated with plasma concentrations of tamoxifen and its main metabolites N-desmethyltamoxifen, (Z)-4-hydroxytamoxifen and (Z)-Endoxifen. However, CYP2C19*2 and its seven linked SNPs were significantly associated with lower NorEND concentrations, MRNorEND/NDDM and MRNorEND/(Z)-END. Specifically, patients carrying the CYP2C19*2 variant allele A had significantly lower NorEND concentrations [median (range), GG vs. GA vs. AA: 1.51 (0.38–3.28) vs. 1.28 (0.30–3.36) vs. 1.15 ng ml−1 (0.26–2.45, P = 0.010)] as well as significantly lower MRNorEND/(Z)-END [GG vs. GA vs. AA: 9.40 (3.27–28.35) vs. 8.15 (2.67–18.9) vs. 6.06 (4.47–14.6), P < 0.0001] and MRNorEND/NDDM [GG vs. GA vs. AA: 2.75 (0.62–6.26) vs. 2.43 (0.96–4.18) vs. 1.75 (1.10–2.49), P < 0.00001]. CYP2C19 H2 haplotype, which included CYP2C19*2, was also significantly associated with lower NorEND concentrations (P = 0.0020), MRNorEND/NDDM (P < 0.0001) and MRNorEND/(Z)-END (P < 0.0001), indicating significantly lower formation rates of NorEND. CONCLUSION These data highlight the potential relevance of CYP2C19 pharmacogenetics in influencing NorEND concentrations in tamoxifen-treated patients, which may influence treatment outcomes.