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Introduction: Tumor genomic testing (TGT) is standard-of-care for most patients with advanced/metastatic cancer. Despite established guidelines, patient education prior to TGT is frequently omitted. The purpose of this study was to evaluate the impact of a concise 4 min video for patient education prior to TGT., Methods: Based on a quality improvement cycle, an animated video was created to be applicable to any cancer type, incorporating culturally diverse images, available in English and Spanish. Patients undergoing standard-of-care TGT were enrolled at a tertiary academic institution and completed survey instruments prior to video viewing (T1) and immediately post-viewing (T2). Instruments included: (1) 10-question objective genomic knowledge; (2) 10-question video message-specific knowledge; (3) 11-question Trust in Provider; (4) attitudes regarding TGT., Results: A total of 150 participants were enrolled. For the primary objective, there was a significant increase in video message-specific knowledge (median 10 point increase; p < 0.0001) with no significant change in genomic knowledge/understanding (p = 0.89) or trust in physician/provider (p = 0.59). Results for five questions significantly improved, including the likelihood of TGT impact on treatment decision, incidental germline findings, and cost of testing. Improvement in video message-specific knowledge was consistent across demographic groups, including age, income, and education., Conclusions: A concise, 3-4 min, broadly applicable video incorporating culturally diverse images administered prior to TGT significantly improved video message-specific knowledge across all demographic groups. This resource is publicly available at http://www.tumor-testing.com, with a goal to efficiently educate and empower patients regarding TGT while addressing guidelines within the flow of clinical practice., (© 2024 The Author(s). Cancer Medicine published by John Wiley & Sons Ltd.)

Purpose: Neither the United States nor the European oncology guidelines include details for appropriate management of hyperglycemia in cancer patients. The aim was to identify fasting and random blood glucose thresholds, and hemoglobin A1c (HbA1c) targets used by oncologists in clinical practice when managing hyperglycemia in patients with cancer undergoing chemotherapy., Methods: This national, cross sectional study utilized a questionnaire to collect oncologists' perceptions about optimal blood glucose thresholds and HbA1c targets in patients with cancer undergoing chemotherapy. Descriptive statistics were calculated to summarize glucose thresholds, HbA1c targets, and sample characteristics. Responses to an open-ended question about oncologists' approach to hyperglycemia management were analyzed via thematic analysis using an inductive approach., Results: Respondents (n = 229) were on average 52.1 years of age, 67.7% men, and 91.3% White. For patients without diabetes but experiencing hyperglycemia, oncologists targeted lower and upper fasting blood glucose levels between 75-121 mg/dL and 105-135 mg/dL, respectively. For patients with diabetes, the targets for lower and upper fasting blood glucose levels ranged between 100-130 mg/dL and 128-150 mg/dL, respectively. Fasting blood glucose (95.6%) and HbA1c (78.6%) were the most commonly used clinical indicators to consider chemotherapy dose reduction, delay, or discontinuation due to hyperglycemia in patients receiving chemotherapy with curative intent. Among those receiving palliative intent chemotherapy, the preferred clinical parameters were random blood glucose (90.0%), patient-reported blood glucose readings (70.7%), continuous glucose monitoring readings (65.1%), and patient-reported symptoms of hyperglycemia (65.1%). Three main themes emerged about oncologists' approach to hyperglycemia management: 1) identification of high-risk patients; 2) need for early identification, screening, and diagnosis of hyperglycemia; and 3) multiple hyperglycemia management strategies., Conclusion: Oncologists reported a wide variation of target blood glucose ranges considered appropriate in patients undergoing chemotherapy. Lack of clear guidance for hyperglycemia management during chemotherapy in the United States may be contributing to a lack of consistency in clinical practice., (© 2024. The Author(s).)

Background: Tumor genomic testing (TGT) has become standard-of-care for most patients with advanced/metastatic cancer. Despite established guidelines, patient education prior to TGT is variable or frequently omitted. The purpose of this study was to evaluate the impact of a concise (3-4 minute) video for patient education prior to TGT., Methods: Based on a quality improvement cycle, an animated video was created to be applicable to any cancer type, incorporating culturally diverse images, available in English and Spanish. Patients undergoing standard-of care TGT were enrolled at a tertiary academic institution and completed validated survey instruments immediately prior to video viewing (T1) and immediately post-viewing (T2). Instruments included: 1) 10-question objective genomic knowledge/understanding; 2) 10-question video message-specific knowledge/recall; 3) 11-question Trust in Physician/Provider; 4) attitudes regarding TGT. The primary objective was change in outcomes from before to after the video was assessed with Wilcoxon signed rank test., Results: From April 2022 to May 2023, a total of 150 participants were enrolled (MBC n=53, LC n=38, OC n=59). For the primary endpoint, there was a significant increase in video message-specific knowledge (median 10 point increase; p<0.0001) with no significant change in genomic knowledge/understanding (p=0.89) or Trust in Physician/Provider (p=0.59). Results for five questions significantly improved, including the likelihood of TGT impact on treatment decision, incidental germline findings, and cost of testing. Improvement in video message-specific knowledge was consistent across demographic groups, including age, income, and education. Individuals with less educational attainment had had greater improvement from before to after video viewing., Conclusions: A concise, 3-4 minute, broadly applicable video incorporating culturally diverse images administered prior to TGT significantly improved video message-specific knowledge across all demographic groups. This resource is publicly available at http://www.tumor-testing.com, with a goal to efficiently educate and empower patients regarding TGT while addressing guidelines within the flow of clinical practice., Clinical Trial Registration: ClinicalTrials.gov NCT05215769., Competing Interests: Conflict of interest disclosure statement: HH is on the scientific advisory board for Invitae Genetics, Genome Medical, and Promega. She has stock/stock options in Genome Medical and GI OnDemand. LS is a consultant and speaker for AstraZeneca. DS served on an advisory board for Novartis. CJP received payment for patient education material development through Jazz Pharmaceuticals.

Purpose: To assess oncologists' responsibility, comfort, and knowledge managing hyperglycemia in patients undergoing chemotherapy., Methods: In this cross-sectional study, a questionnaire collected oncologists' perceptions about professionals responsible for managing hyperglycemia during chemotherapy; comfort (score range 12-120); and knowledge (score range 0-16). Descriptive statistics were calculated including Student t-tests and one-way ANOVA for mean score differences. Multivariable linear regression identified predictors of comfort and knowledge scores., Results: Respondents (N = 229) were 67.7% men, 91.3% White and mean age 52.1 years. Oncologists perceived endocrinologists/diabetologists and primary care physicians as those responsible for managing hyperglycemia during chemotherapy, and most frequently referred to these clinicians. Reasons for referral included lack of time to manage hyperglycemia (62.4%), belief that patients would benefit from referral to an alternative provider clinician (54.1%), and not perceiving hyperglycemia management in their scope of practice (52.4%). The top-3 barriers to patient referral were long wait times for primary care (69.9%) and endocrinology (68.1%) visits, and patient's provider outside of the oncologist's institution (52.8%). The top-3 barriers to treating hyperglycemia were lack of knowledge about when to start insulin, how to adjust insulin, and what insulin type works best. Women (ß = 1.67, 95% CI: 0.16, 3.18) and oncologists in suburban areas (ß = 6.98, 95% CI: 2.53, 11.44) had higher comfort scores than their respective counterparts; oncologists working in practices with > 10 oncologists had lower comfort scores (ß = -2.75, 95% CI: -4.96, -0.53) than those in practices with ≤ 10. No significant predictors were identified for knowledge., Conclusion: Oncologists expected endocrinology or primary care clinicians to manage hyperglycemia during chemotherapy, but long wait times were among the top barriers cited when referring patients. New models that provide prompt and coordinated care are needed., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: This guideline updates recommendations of the ASCO guideline on chemotherapy and targeted therapy for patients with human epidermal growth factor receptor 2-negative metastatic breast cancer (MBC) that is either endocrine-pretreated or hormone receptor (HR)-negative., Methods: An Expert Panel conducted a targeted systematic literature review guided by a signals approach to identify new, potentially practice-changing data that might translate into revised guideline recommendations., Results: The Expert Panel reviewed abstracts from the literature review and retained 14 articles., Recommendations: Patients with triple-negative, programmed cell death ligand-1-positive MBC may be offered the addition of immune checkpoint inhibitor to chemotherapy as first-line therapy. Patients with triple-negative, programmed cell death ligand-1-negative MBC should be offered single-agent chemotherapy rather than combination chemotherapy as first-line treatment, although combination regimens may be offered for life-threatening disease. Patients with triple-negative MBC who have received at least two prior therapies for MBC should be offered treatment with sacituzumab govitecan. Patients with triple-negative MBC with germline BRCA mutations previously treated with chemotherapy may be offered a poly (ADP-ribose) polymerase inhibitor rather than chemotherapy. Patients with HR-positive human epidermal growth factor receptor 2-negative MBC for whom chemotherapy is being considered should be offered single-agent chemotherapy rather than combination chemotherapy, although combination regimens may be offered for highly symptomatic or life-threatening disease. Patients with HR-positive MBC with disease progression on an endocrine agent may be offered treatment with either endocrine therapy with or without targeted therapy or single-agent chemotherapy. Patients with HR-positive MBC with germline BRCA mutations no longer benefiting from endocrine therapy may be offered a poly (ADP-ribose) polymerase inhibitor rather than chemotherapy. No recommendation regarding when a patient's care should be transitioned to hospice or best supportive care alone is possible.Additional information is available at www.asco.org/breast-cancer-guidelines., Competing Interests: Beverly MoyConsulting or Advisory Role: MOTUSResearch Funding: Puma Biotechnology Steven E. ComeResearch Funding: AstraZenecaOpen Payments Link: https://openpaymentsdata.cms.gov/physician/163830/summary Angelo Di LeoHonoraria: Roche, Novartis, Pfizer, AstraZeneca, Eisai, Lilly, Celgene, AmgenConsulting or Advisory Role: Roche, Novartis, Pfizer, AstraZeneca, Lilly, Celgene, Puma Biotechnology, Ipsen, Genentech, Amgen, Seattle Genetics, Genomic Health, Athenex, Daiichi SankyoTravel, Accommodations, Expenses: Roche, Pfizer, Celgene, Novartis Julie R. GralowConsulting or Advisory Role: Genentech, AstraZeneca, Hexal, Puma Biotechnology, Roche, Novartis, Seagen, Genomic Health Gabriel N. HortobagyiConsulting or Advisory Role: NovartisResearch Funding: NovartisTravel, Accommodations, Expenses: Novartis Douglas YeeStock and Other Ownership Interests: Apogen BiotechnologiesHonoraria: Puma Biotechnology, Daiichi Sankyo, Boehringer IngelheimConsulting or Advisory Role: Martell diagnosticResearch Funding: Boehringer IngelheimOpen Payments Link: https://openpaymentsdata.cms.gov/physician/636443/summary Ian E. SmithStock and Other Ownership Interests: Perci HealthHonoraria: Eisai, AstraZeneca, Genomic Health, PfizerConsulting or Advisory Role: Roche, AstraZeneca, Eisai, Pfizer, Genomic HealthTravel, Accommodations, Expenses: Genomic Health Mariana Chavez-MacGregorEmployment: MD Anderson Physician's NetworkHonoraria: Pfizer, EisaiConsulting or Advisory Role: Roche/Genentech, AstraZeneca, Novartis, Pfizer, Asofar, Genomic Health, Roche/GenentechResearch Funding: NovartisExpert Testimony: Abbott Laboratories, PfizerTravel, Accommodations, Expenses: PfizerOther Relationship: RocheUncompensated Relationships: Legacy Healthcare Services, The Hope Foundation Rita NandaConsulting or Advisory Role: Merck, Genentech/Roche, Pfizer, Macrogenics, Aduro Biotech, Ionis Pharmaceuticals, Immunomedics, OncoSec, Cardinal Health, Seattle Genetics, Fujifilm, Clovis Oncology, G1 TherapeuticsResearch Funding: Corcept Therapeutics, Celgene, Merck, Seattle Genetics, Genentech/Roche, Odonate Therapeutics, Pfizer, AstraZeneca, Immunomedics, OncoSec, Arvinas, Taiho OncologyOther Relationship: G1 Therapeutics Heather L. McArthurConsulting or Advisory Role: Merck, Lilly, Immunomedics, Pfizer, Genentech, Bristol Myers Squibb, AstraZeneca , Daiichi Sankyo, Seattle Genetics, Genomic Health, Puma BiotechnologyResearch Funding: Bristol Myers Squibb, ZIOPHARM Oncology, Lilly, MerckTravel, Accommodations, Expenses: Merck, Spectrum Pharmaceuticals, Lilly, Amgen, Puma Biotechnology, Immunomedics, Genentech, Pfizer, AstraZeneca, Bristol Myers Squibb, DAVA PharmaceuticalsOther Relationship: Lilly, Genomic Health Laura SpringConsulting or Advisory Role: Novartis, Puma Biotechnology, Lumicell, AvrobioResearch Funding: Tesaro, MerckTravel, Accommodations, Expenses: Merck, Tesaro Katherine E. Reeder-HayesResearch Funding: Pfizer Kathryn J. RuddyResearch Funding: MedtronicPatents, Royalties, Other Intellectual Property: Spouse and Mayo Clinic have filed patents related to the application of artificial intelligence to the electrocardiogram for diagnosis and risk stratification, and Spouse and Mayo Clinic are involved in a potential equity/royalty relationship with AliveCor Shaveta VinayakConsulting or Advisory Role: OncoSecResearch Funding: OncoSec, Seattle Genetics, PfizerTravel, Accommodations, Expenses: OncoSec William J. Irvin JrResearch Funding: Merck, Altor BioScience, Odonate Therapeutics, Boston Biomedical, Novartis, Pfizer, Seattle Genetics, AstraZeneca Michael A. DansoHonoraria: AmgenConsulting or Advisory Role: Novartis, Pfizer, Immunomedics, Seattle Genetics Natalie DicksonEmployment: Tennessee OncologyConsulting or Advisory Role: Via Oncology, AbbVie, CignaResearch Funding: Bristol Myers SquibbTravel, Accommodations, Expenses: Flatiron Health Sophie S. TurnerEmployment: IQVIA Cheryl PerkinsEmployment: Medscape Lisa A. CareyResearch Funding: Syndax, Immunomedics, Novartis, NanoString Technologies, AbbVie, Seattle Genetics, VeracytePatents, Royalties, Other Intellectual Property: Royalty-sharing agreement, investorship interest in licensed IP to startup company, Falcon Therapeutics, that is designing neural stem-cell–based therapy for glioblastoma multiformeUncompensated Relationships: Sanofi, Novartis, G1 Therapeutics, Genentech/Roche, GlaxoSmithKline, AstraZeneca/Daiichi Sankyo, Aptitude Health, Exact Sciences, EisaiOpen Payments Link: https://openpaymentsdata.cms.gov/physician/179671No other potential conflicts of interest were reported.

Objectives: Tamoxifen bioactivation to endoxifen is mediated primarily by CYP2D6; however, considerable variability remains unexplained. Our aim was to perform a comprehensive assessment of the effect of genetic variation in tamoxifen-relevant enzymes and transporters on steady-state endoxifen concentrations., Patients and Methods: Comprehensive genotyping of CYP enzymes and transporters was performed using the iPLEX ADME PGx Pro Panel in 302 tamoxifen-treated breast cancer patients. Predicted activity phenotype for 19 enzymes and transporters were analyzed for univariate association with endoxifen concentration, and then adjusted for CYP2D6 and clinical covariates., Results: In univariate analysis, higher activity of CYP2C8 (regression β=0.22, P=0.020) and CYP2C9 (β=0.20, P=0.04), lower body weight (β=-0.014, P<0.0001), and endoxifen measurement during winter (each β<-0.39, P=0.002) were associated with higher endoxifen concentrations. After adjustment for the CYP2D6 diplotype, weight, and season, CYP2C9 remained significantly associated with higher concentrations (P=0.02), but only increased the overall model R by 1.3%., Conclusion: Our results further support a minor contribution of CYP2C9 genetic variability toward steady-state endoxifen concentrations. Integration of clinician and genetic variables into individualized tamoxifen dosing algorithms would marginally improve their accuracy and potentially enhance tamoxifen treatment outcomes.

Background: Polymorphic CYP2D6 is primarily responsible for metabolic activation of tamoxifen to endoxifen. We previously reported that by increasing the daily tamoxifen dose to 40 mg/day in CYP2D6 intermediate metabolizer (IM), but not poor metabolizer (PM), patients achieve endoxifen concentrations similar to those of extensive metabolizer patients on 20 mg/day. We expanded enrollment to assess the safety of CYP2D6 genotype-guided dose escalation and investigate concentration differences between races., Methods: PM and IM breast cancer patients currently receiving tamoxifen at 20 mg/day were enrolled for genotype-guided escalation to 40 mg/day. Endoxifen was measured at baseline and after 4 months. Quality-of-life data were collected using the Functional Assessment of Cancer Therapy-Breast (FACT-B) and Breast Cancer Prevention Trial Menopausal Symptom Scale at baseline and after 4 months., Results: In 353 newly enrolled patients, genotype-guided dose escalation eliminated baseline concentration differences in IM (p = .08), but not PM (p = .009), patients. Endoxifen concentrations were similar in black and white patients overall (p = .63) and within CYP2D6 phenotype groups (p > .05). In the quality-of-life analysis of 480 patients, dose escalation did not meaningfully diminish quality of life; in fact, improvements were seen in several measures including the FACT Breast Cancer subscale (p = .004) and limitations in range of motion (p < .0001) in IM patients., Conclusion: Differences in endoxifen concentration during treatment can be eliminated by doubling the tamoxifen dose in IM patients, without an appreciable effect on quality of life. Validation of the association between endoxifen concentration and efficacy or prospective demonstration of improved efficacy is necessary to warrant clinical uptake of this personalized treatment strategy., Implications for Practice: This secondary analysis of a prospective CYP2D6 genotype-guided tamoxifen dose escalation study confirms that escalation to 40 mg/day in patients with low-activity CYP2D6 phenotypes (poor or intermediate metabolizers) increases endoxifen concentrations without any obvious increases in treatment-related toxicity. It remains unknown whether endoxifen concentration is a useful predictor of tamoxifen efficacy, and thus, there is no current role in clinical practice for CYP2D6 genotype-guided tamoxifen dose adjustment. If future studies confirm the importance of endoxifen concentrations for tamoxifen efficacy and report a target concentration, this study provides guidance for a dose-adjustment approach that could maximize efficacy while maintaining patient quality of life., (©AlphaMed Press.)

Aims: A prospectively enrolled patient cohort was used to assess whether the prediction of CYP2D6 phenotype activity from genotype data could be improved by reclassification of diplotypes or alleles., Methods: Three hundred and fifty-five patients receiving tamoxifen 20 mg were genotyped for CYP2D6 and tamoxifen metabolite concentrations were measured. The endoxifen : N-desmethly-tamoxifen metabolic ratio, as a surrogate of CYP2D6 activity, was compared across four diplotypes (EM/IM, EM/PM, IM/IM, IM/PM) that are typically collapsed into an intermediate metabolizer (IM) phenotype. The relative metabolic activity of each allele type (UM, EM, IM, and PM) and each EM and IM allele was estimated for comparison with the activity scores typically assigned, 2, 1, 0.5 and 0, respectively., Results: Each of the four IM diplotypes have distinct CYP2D6 activity from each other and from the EM and PM phenotype groups (each P < 0.05). Setting the activity of an EM allele at 1.0, the relative activities of a UM, IM and PM allele were 0.85, 0.67 and 0.52, respectively. The activity of the EM alleles were statistically different (P < 0.0001), with the CYP2D6*2 allele (scaled activity = 0.63) closer in activity to an IM than an EM allele. The activity of the IM alleles were also statistically different (P = 0.014)., Conclusion: The current systems for translating CYP2D6 genotype into phenotype are not optimally calibrated, particularly in regards to IM diplotypes and the *2 allele. Additional research is needed to improve the prediction of CYP2D6 activity from genetic data for individualized dosing of CYP2D6 dependent drugs., (© 2015 The British Pharmacological Society.)

Purpose: Circulating tumor cells (CTC) are prognostic in metastatic breast cancer (MBC). We tested whether EpCAM-based capture system (CellSearch) is effective in patients with triple-negative (TN) MBC, and whether CTC apoptosis and clustering enhances the prognostic role of CTC., Experimental Design: CTC enumeration and apoptosis were determined using the CXC CellSearch kit at baseline and days 15 and 29 in blood drawn from TN MBC patients who participated in a prospective randomized phase II trial of nanoparticle albumin-bound paclitaxel (nab-paclitaxel) with or without tigatuzumab. Association between levels of CTC and patient outcomes was assessed using logistic regression, Kaplan-Meier curves, and Cox proportional hazards modeling., Results: Nineteen of 52 (36.5%), 14 of 52 (26.9%), and 13 of 49 (26.5%) patients who were evaluable had elevated CTC (≥5 CTC/7.5 mL whole blood) at baseline and at days 15 and 29, respectively. Patients with elevated versus not elevated CTC at each time point had worse progression-free survival (PFS; P = 0.005, 0.0003, 0.0002, respectively). The odds of clinical benefit response for those who had elevated versus low CTC at baseline and days 15 and 29 were 0.25 (95% CI: 0.08-0.84; P = 0.024), 0.19 (95% CI: 0.05-0.17; P = 0.014), and 0.06 (95% CI: 0.01-0.33; P = 0.001), respectively. There was no apparent prognostic effect comparing CTC apoptosis versus non-apoptosis. Presence of CTC cluster at day 15 and day 29 was associated with shorter PFS., Conclusions: CTC were detected using CellSearch assay in approximately one-third of TN MBC patients. Elevated CTC at baseline and days 15 and 29 were prognostic, and reductions in CTC levels reflected response., (©2015 American Association for Cancer Research.)

Purpose: Tigatuzumab (TIG), an agonistic anti-DR5 antibody, triggers apoptosis in DR5(+) human tumor cells without crosslinking. TIG has strong in vitro/in vivo activity against basal-like breast cancer cells enhanced by chemotherapy agents. This study evaluates activity of TIG and chemotherapy in patients with metastatic triple-negative breast cancer (TNBC)., Experimental Design: Randomized 2:1 phase II trial of albumin-bound paclitaxel (nab-PAC) ± TIG in patients with TNBC stratified by prior chemotherapy. Patients received nab-PAC weekly × 3 ± TIG every other week, every 28 days. Primary objective was within-arm objective response rate (ORR). Secondary objectives were safety, progression-free survival (PFS), clinical benefit, and TIG immunogenicity. Metastatic research biopsies were required., Results: Among 64 patients (60 treated; TIG/nab-PAC n = 39 and nab-PAC n = 21), there were 3 complete remissions (CR), 8 partial remissions (PR; 1 almost CR), 11 stable diseases (SD), and 17 progressive diseases (PD) in the TIG/nab-PAC arm (ORR, 28%), and no CRs, 8 PRs, 4 SDs, and 9 PDs in the nab-PAC arm (ORR, 38%). There was a numerical increase in CRs and several patients had prolonged PFS (1,025+, 781, 672, 460, 334) in the TIG/nab-PAC arm. Grade 3 toxicities were 28% and 29%, respectively, with no grade 4-5. Exploratory analysis suggests an association of ROCK1 gene pathway activation with efficacy in the TIG/nab-PAC arm., Conclusions: ORR and PFS were similar in both. Preclinical activity of TIG in basal-like breast cancer and prolonged PFS in few patients in the combination arm support further investigation of anti-DR5 agents. ROCK pathway activation merits further evaluation., (©2015 American Association for Cancer Research.)

Background: CYP2D6 is a critical enzyme in the metabolism of tamoxifen and potentially a key determinant in breast cancer outcomes. Our study examined patients' beliefs about how the CYP2D6 genotype would affect their prognoses., Methods: Women enrolled in a pharmacogenomic clinical trial and on tamoxifen for prevention or treatment of breast cancer underwent CYP2D6 genotyping (EM = extensive, IM = intermediate, PM = poor metabolizing alleles). The informed consent said that the purpose of the trial was to examine effects of dose adjustment based on genotype, but that clinical benefits were uncertain. Our embedded sub-study surveyed 320 patients prior to receiving their genotypes. We experimentally manipulated 6 vignettes to describe hypothetical tamoxifen treatment (no or yes) and hypothetical genotype (EM, IM or PM). For each vignette, women gave their perceived recurrence risk (RR; 0-100%)., Results: Women believed that genotype would not affect their RR if they did not take tamoxifen (p = 0.06). However, women believed that if prescribed tamoxifen, genotype would affect their RR (22% if EM, 30% if IM and 40% if PM, p < 0.001)., Conclusion: Women believed that extensive tamoxifen metabolizers had better prognoses, despite study materials stating uncertainty about any benefit. The rapidly changing nature of genomic science calls for caution when communicating clinical utility.

Tamoxifen is an effective antiestrogen used in the treatment of hormone receptor-positive breast cancer. Bioconversion of tamoxifen to endoxifen, its most abundant active metabolite, is primarily dependent on the activity of cytochrome P450 2D6 (CYP2D6), which is highly polymorphic. Over 20 published studies have reported on the potential association between CYP2D6 polymorphism and tamoxifen treatment outcome, with highly inconsistent results. The purpose of this review is to explore differences among 17 independent studies to identify factors that may have contributed to the discrepant findings. This report discusses six putative factors that are grouped into two categories: (a) clinical management criteria: hormone receptor classification, menopausal status, and tamoxifen combination therapy; (b) pharmacologic criteria: genotyping comprehensiveness, CYP2D6 inhibitor coadministration, and tamoxifen adherence. Comparison of these factors between the positive and negative studies suggests that tamoxifen combination therapy, genotyping comprehensiveness, and CYP2D6 inhibitor coadministration may account for some of the contradictory results. Future association studies on the link between CYP2D6 genotype and tamoxifen treatment efficacy should account for combination therapy and CYP2D6 inhibition, and interrogate as many CYP2D6 alleles as possible.

Purpose: We examined the feasibility of using CYP2D6 genotyping to determine optimal tamoxifen dose and investigated whether the key active tamoxifen metabolite, endoxifen, could be increased by genotype-guided tamoxifen dosing in patients with intermediate CYP2D6 metabolism., Patients and Methods: One hundred nineteen patients on tamoxifen 20 mg daily ≥ 4 months and not on any strong CYP2D6 inhibiting medications were assayed for CYP2D6 genotype and plasma tamoxifen metabolite concentrations. Patients found to be CYP2D6 extensive metabolizers (EM) remained on 20 mg and those found to be intermediate (IM) or poor (PM) metabolizers were increased to 40 mg daily. Eighty-nine evaluable patients had tamoxifen metabolite measurements repeated 4 months later., Results: As expected, the median baseline endoxifen concentration was higher in EM (34.3 ng/mL) compared with either IM (18.5 ng/mL; P = .0045) or PM (4.2 ng/mL; P < .001). When the dose was increased from 20 mg to 40 mg in IM and PM patients, the endoxifen concentration rose significantly; in IM there was a median intrapatient change from baseline of +7.6 ng/mL (-0.6 to 23.9; P < .001), and in PM there was a change of +6.1 ng/mL (2.6 to 12.5; P = .020). After the dose increase, there was no longer a significant difference in endoxifen concentrations between EM and IM patients (P = .84); however, the PM endoxifen concentration was still significantly lower., Conclusion: This study demonstrates the feasibility of genotype-driven tamoxifen dosing and demonstrates that doubling the tamoxifen dose can increase endoxifen concentrations in IM and PM patients.

Background: Based on preclinical studies and a phase I trial of the combination of bortezomib and pegylated liposomal doxorubicin (PLD), which both showed activity in breast cancer, we conducted a phase II study of this regimen in patients with metastatic breast cancer., Patients and Methods: Patients received bortezomib 1.3 mg/m2 on days 1, 4, 8, and 11 of an every-21-day cycle, along with PLD 30 mg/m2 on day 4. The primary objective was to evaluate the response rate of this combination, while secondary objectives were to obtain further safety data about this combination, to evaluate the time to disease progression (TTP), and to evaluate response by the breast cancer subtype., Results: One of 12 evaluable patients had a partial response (8%), while 3 (25%) had stable disease. At 26 months follow-up, the median overall survival was 4.3 months (95% CI, 1.2-26.2) and the median TTP was 1.3 months (95% CI, 0.8-14.0 months). The combination was well tolerated, with the most common events including low-grade nausea and vomiting, neutropenia, and neuropathy, and no cardiac toxicity was seen. Of the 7 tumors subtyped, no association was seen between intrinsic subtype or receptor status and response., Conclusion: The combination of PLD and bortezomib was well tolerated but has minimal activity in heavily pretreated unselected metastatic breast cancer.

Triple-negative (ER-negative, PR-negative, HER2/neu not overexpressed) breast cancer has distinct clinical and pathologic features, and is a clinical problem because of its relatively poor prognosis, aggressive behaviour and lack of targeted therapies, leaving chemotherapy as the mainstay of treatment. Most triple-negative tumours fall into the basal-like molecular subtype of breast cancer, but the terms are not completely synonymous. Among the intriguing characteristics of triple-negative breast cancer is its association with cancers arising in BRCA1 mutation carriers, in young women and in African-American women. The reasons for these associations are unclear but may ultimately provide avenues for prevention and targeted therapy. This review discusses the definitions and characteristics of as well as current and evolving therapies for triple-negative and basal-like breast cancer.