Multi-site investigation of strategies for the clinical implementation of CYP2D6 genotyping to guide drug prescribing.

PURPOSE: A number of institutions have clinically implemented CYP2D6 genotyping to guide drug prescribing. We compared implementation strategies of early adopters of CYP2D6 testing, barriers faced by both early adopters and institutions in the process of implementing CYP2D6 testing, and approaches taken to overcome these barriers. METHODS: We surveyed eight early adopters of CYP2D6 genotyping and eight institutions in the process of adoption. Data were collected on testing approaches, return of results procedures, applications of genotype results, challenges faced, and lessons learned. RESULTS: Among early adopters, CYP2D6 testing was most commonly ordered to assist with opioid and antidepressant prescribing. Key differences among programs included test ordering and genotyping approaches, result reporting, and clinical decision support. However, all sites tested for copy-number variation and nine common variants, and reported results in the medical record. Most sites provided automatic consultation and had designated personnel to assist with genotype-informed therapy recommendations. Primary challenges were related to stakeholder support, CYP2D6 gene complexity, phenotype assignment, and sustainability. CONCLUSION: There are specific challenges unique to CYP2D6 testing given the complexity of the gene and its relevance to multiple medications. Consensus lessons learned may guide those interested in pursuing similar clinical pharmacogenetic programs.

Patient perspectives on the barriers associated with medication adherence to oral chemotherapy.

Purpose Appropriate use of oral chemotherapy is a challenge for patients and clinicians. The purpose of this study was to analyze cancer patients' use of oral chemotherapies and identify opportunities to improve adherence. Methods We developed a 30-question survey to address frequency and reasons for reducing/skipping doses; sources of information for oral chemotherapy use; perceived importance of food-drug effects; and ease of understanding labeling directions. Results Ninety-three patients taking oral chemotherapies with chronic myeloid leukemia, renal cell carcinoma, breast cancer, and colorectal cancer completed the survey. This was a well-educated population with 69% (n = 62) having completed some college; 51% (n = 47) female and 59% (n = 54) older than 50 years of age. Thirty percent of patients reported forgetting to take their oral chemotherapy at least "sometimes". Younger patients (<50 vs. ≥50, p = 0.002), shorter treatment duration (<6 vs. ≥6 months p = 0.03), or with chronic myeloid leukemia (vs. other diagnoses, p = 0.015) forget to take their oral chemotherapy at higher rates. Twenty-three percent (n = 21) indicated they intentionally skipped their oral chemotherapies and 38% (n = 8) of those did not inform their physicians. Forty-one percent (n = 28) taking drugs with significant food-drug effects did not think about their last meal before taking their oral chemotherapy and 80% (n = 55) did not understand the potential interactions. Additionally, 39% (n = 36/92) never looked at labeling and 15% (n = 14/91) had difficulty understanding label directions. Conclusion There are three main barriers associated with appropriate use of oral chemotherapies: misunderstanding about the timing of drug with food; stopping drug without informing physicians; and difficulty understanding labeling directions. A multipronged approach is needed to optimize communication of directions for optimal oral chemotherapy use.

International network of cancer genome projects.

The International Cancer Genome Consortium (ICGC) was launched to coordinate large-scale cancer genome studies in tumours from 50 different cancer types and/or subtypes that are of clinical and societal importance across the globe. Systematic studies of more than 25,000 cancer genomes at the genomic, epigenomic and transcriptomic levels will reveal the repertoire of oncogenic mutations, uncover traces of the mutagenic influences, define clinically relevant subtypes for prognosis and therapeutic management, and enable the development of new cancer therapies.

Ethical and practical challenges of sharing data from genome-wide association studies: the eMERGE Consortium experience.

In 2007, the National Human Genome Research Institute (NHGRI) established the Electronic MEdical Records and GEnomics (eMERGE) Consortium (www.gwas.net) to develop, disseminate, and apply approaches to research that combine DNA biorepositories with electronic medical record (EMR) systems for large-scale, high-throughput genetic research. One of the major ethical and administrative challenges for the eMERGE Consortium has been complying with existing data-sharing policies. This paper discusses the challenges of sharing genomic data linked to health information in the electronic medical record (EMR) and explores the issues as they relate to sharing both within a large consortium and in compliance with the National Institutes of Health (NIH) data-sharing policy. We use the eMERGE Consortium experience to explore data-sharing challenges from the perspective of multiple stakeholders (i.e., research participants, investigators, and research institutions), provide recommendations for researchers and institutions, and call for clearer guidance from the NIH regarding ethical implementation of its data-sharing policy.

Integrating personalized genomic medicine into routine clinical care: addressing the social and policy issues of pharmacogenomic testing.

The provision of personalized genomic medicine presents significant policy challenges, such as ensuring equitable patient access to testing, preparing clinicians to manage genomic results, justifying test reimbursement, sharing genomic information for patient care, and protecting patients against misuse of genetic information.

Ethical aspects of participation in the database of genotypes and phenotypes of the National Center for Biotechnology Information: the Cancer and Leukemia Group B Experience.

BACKGROUND: The rapid pace of genetics research, coupled with evolving standards for informed consent, can create ethical challenges regarding future use of tissue or information from completed clinical trials. The Cancer and Leukemia Group B (CALGB) Oncology Cooperative Group was faced with an ethical dilemma regarding sharing genetic data from a completed genome-wide association study (GWAS) that was conducted as part of a large, multicenter breast cancer clinical trial with a national database: the Database of Genotypes and Phenotypes National Center for Biotechnology Information (dbGaP). METHODS: The CALGB Ethics Committee conducted a series of multidisciplinary meetings and teleconferences involving patient advocates, bioethicists, clinical researchers, and clinical oncologists to evaluate the ethical issues raised by this case and to identify lessons for improving informed consent to future genetics research in oncology trials. RESULTS: The Ethics Committee recommended that GWAS data be provided to dbGaP consistent with documented consent for future use of tissue among trial participants. Ethical issues, including adequacy of informed consent to future research, limitations of privacy in modern genetics research, the potential impact of population-based genetics research on health disparities, and recontact of research participants for clinical care or further research, were identified as major ethical considerations in this area. CONCLUSIONS: Although modern standards for informed consent should not prohibit research or sharing of data consistent with participant's intent and the public interest, there is an urgent need for national consensus on the appropriate use of archived tissue and standardized informed consent for future research among cancer clinical trial participants.

Adjuvant chemotherapy in older women with early-stage breast cancer.

BACKGROUND: Older women with breast cancer are underrepresented in clinical trials, and data on the effects of adjuvant chemotherapy in such patients are scant. We tested for the noninferiority of capecitabine as compared with standard chemotherapy in women with breast cancer who were 65 years of age or older. METHODS: We randomly assigned patients with stage I, II, IIIA, or IIIB breast cancer to standard chemotherapy (either cyclophosphamide, methotrexate, and fluorouracil or cyclophosphamide plus doxorubicin) or capecitabine. Endocrine therapy was recommended after chemotherapy in patients with hormone-receptor-positive tumors. A Bayesian statistical design was used with a range in sample size from 600 to 1800 patients. The primary end point was relapse-free survival. RESULTS: When the 600th patient was enrolled, the probability that, with longer follow-up, capecitabine therapy was highly likely to be inferior to standard chemotherapy met a prescribed level, and enrollment was discontinued. After an additional year of follow-up, the hazard ratio for disease recurrence or death in the capecitabine group was 2.09 (95% confidence interval, 1.38 to 3.17; P<0.001). Patients who were randomly assigned to capecitabine were twice as likely to have a relapse and almost twice as likely to die as patients who were randomly assigned to standard chemotherapy (P=0.02). At 3 years, the rate of relapse-free survival was 68% in the capecitabine group versus 85% in the standard-chemotherapy group, and the overall survival rate was 86% versus 91%. Two patients in the capecitabine group died of treatment-related complications; as compared with patients receiving capecitabine, twice as many patients receiving standard chemotherapy had moderate-to-severe toxic effects (64% vs. 33%). CONCLUSIONS: Standard adjuvant chemotherapy is superior to capecitabine in patients with early-stage breast cancer who are 65 years of age or older. (ClinicalTrials.gov number, NCT00024102.)

Chemotherapy response and recurrence-free survival in neoadjuvant breast cancer depends on biomarker profiles: results from the I-SPY 1 TRIAL (CALGB 150007/150012; ACRIN 6657).

Neoadjuvant chemotherapy for breast cancer allows individual tumor response to be assessed depending on molecular subtype, and to judge the impact of response to therapy on recurrence-free survival (RFS). The multicenter I-SPY 1 TRIAL evaluated patients with ≥ 3 cm tumors by using early imaging and molecular signatures, with outcomes of pathologic complete response (pCR) and RFS. The current analysis was performed using data from patients who had molecular profiles and did not receive trastuzumab. The various molecular classifiers tested were highly correlated. Categorization of breast cancer by molecular signatures enhanced the ability of pCR to predict improvement in RFS compared to the population as a whole. In multivariate analysis, the molecular signatures that added to the ability of HR and HER2 receptors, clinical stage, and pCR in predicting RFS included 70-gene signature, wound healing signature, p53 mutation signature, and PAM50 risk of recurrence. The low risk signatures were associated with significantly better prognosis, and also identified additional patients with a good prognosis within the no pCR group, primarily in the hormone receptor positive, HER-2 negative subgroup. The I-SPY 1 population is enriched for tumors with a poor prognosis but is still heterogeneous in terms of rates of pCR and RFS. The ability of pCR to predict RFS is better by subset than it is for the whole group. Molecular markers improve prediction of RFS by identifying additional patients with excellent prognosis within the no pCR group.

IRB perspectives on the return of individual results from genomic research.

PURPOSE: Return of individual research results from genomic studies is a hotly debated ethical issue in genomic research. However, the perspective of key stakeholders-institutional review board (IRB) professionals-has been missing from this dialogue. This study explores the positions and experiences of IRB members and staff regarding this issue. METHODS: In-depth interviews with 31 IRB professionals at six sites across the United States. RESULTS: IRB professionals agreed that research results should be returned to research participants when results are medically actionable but only if the participants want to know the results. Many respondents expected researchers to address the issue of return of results (ROR) in the IRB application and informed-consent document. Many respondents were not comfortable with their expertise in genomics research and only a few described actual experiences in addressing ROR. Although participants agreed that guidelines would be helpful, most were reticent to develop them in isolation. Even where IRB guidance exists (e.g., Clinical Laboratory Improvement Act (CLIA) lab certification required for return), in practice, the guidance has been overruled to allow ROR (e.g., no CLIA lab performs the assay). CONCLUSION: An IRB-researcher partnership is needed to help inform responsible and feasible institutional approaches to returning research results.

Molecular classification of head and neck squamous cell carcinomas using patterns of gene expression.

The prognostication of head and neck squamous cell carcinoma (HNSCC) is largely based upon the tumor size and location and the presence of lymph node metastases. Here we show that gene expression patterns from 60 HNSCC samples assayed on cDNA microarrays allowed categorization of these tumors into four distinct subtypes. These subtypes showed statistically significant differences in recurrence-free survival and included a subtype with a possible EGFR-pathway signature, a mesenchymal-enriched subtype, a normal epithelium-like subtype, and a subtype with high levels of antioxidant enzymes. Supervised analyses to predict lymph node metastasis status were approximately 80% accurate when tumor subsite and pathological node status were considered simultaneously. This work represents an important step toward the identification of clinically significant biomarkers for HNSCC.

HER2 and response to paclitaxel in node-positive breast cancer.

BACKGROUND: The status of human epidermal growth factor receptor type 2 (HER2) in breast-cancer cells predicts clinical outcomes in women who receive adjuvant anthracycline-based chemotherapy. We hypothesized that HER2 positivity predicts a benefit from adjuvant doxorubicin doses above standard levels, from the addition of paclitaxel after adjuvant chemotherapy with doxorubicin plus cyclophosphamide, or from both. METHODS: We randomly selected 1500 women from 3121 women with node-positive breast cancer who had been randomly assigned to receive doxorubicin (60, 75, or 90 mg per square meter of body-surface area) plus cyclophosphamide (600 mg per square meter) for four cycles, followed by four cycles of paclitaxel (175 mg per square meter) or observation. Tissue blocks from 1322 of these 1500 women were available. Immunohistochemical analyses of these tissue specimens for HER2 with the CB11 monoclonal antibody against HER2 or with a polyclonal-antibody assay kit and fluorescence in situ hybridization for HER2 amplification were performed. RESULTS: No interaction was observed between HER2 positivity and doxorubicin doses above 60 mg per square meter. HER2 positivity was, however, associated with a significant benefit from paclitaxel. The interaction between HER2 positivity and the addition of paclitaxel to the treatment was associated with a hazard ratio for recurrence of 0.59 (P=0.01). Patients with a HER2-positive breast cancer benefited from paclitaxel, regardless of estrogen-receptor status, but paclitaxel did not benefit patients with HER2-negative, estrogen-receptor-positive cancers. CONCLUSIONS: The expression or amplification, or both, of HER2 by a breast cancer is associated with a benefit from the addition of paclitaxel after adjuvant treatment with doxorubicin (<60 mg per square meter) plus cyclophosphamide in node-positive breast cancer, regardless of estrogen-receptor status. Patients with HER2-negative, estrogen-receptor-positive, node-positive breast cancer may gain little benefit from the administration of paclitaxel after adjuvant chemotherapy with doxorubicin plus cyclophosphamide.

Implementing pharmacogenetic testing in rural primary care practices: a pilot feasibility study.

Aim: Assess feasibility and perspectives of pharmacogenetic testing/PGx in rural, primary care physician (PCP) practices when PCPs are trained to interpret/apply results and testing costs are covered. Methods: Participants included PCPs who agreed to training, surveys and interviews and eligible patients who agreed to surveys and testing. 51 patients from three practices participated. Results: Prestudy, no PCP had ever ordered a PGx test. Test results demonstrated gene variations in 30% of patients, related to current medications, with PCPs reporting changes to drug management. Poststudy, test cost was still a concern, but now PCPs reported practical barriers, including the utilization of PGx results over time. PCPs and patients had favorable responses to testing. Summary: PGx testing is feasible in rural PCP practices.

Randomized Trial of Standard Adjuvant Chemotherapy Regimens Versus Capecitabine in Older Women With Early Breast Cancer: 10-Year Update of the CALGB 49907 Trial.

PURPOSE: Older women with breast cancer remain under-represented in clinical trials. The Cancer and Leukemia Group B 49907 trial focused on women age 65 years and older. We previously reported the primary analysis after a median follow-up of 2.4 years. Standard adjuvant chemotherapy showed significant improvements in recurrence-free survival (RFS) and overall survival compared with capecitabine. We now update results at a median follow-up of 11.4 years. PATIENTS AND METHODS: Patients age 65 years or older with early breast cancer were randomly assigned to either standard adjuvant chemotherapy (physician's choice of either cyclophosphamide, methotrexate, and fluorouracil or cyclophosphamide and doxorubicin) or capecitabine. An adaptive Bayesian design was used to determine sample size and test noninferiority of capecitabine. The primary end point was RFS. RESULTS: The design stopped accrual with 633 patients at its first sample size assessment. RFS remains significantly longer for patients treated with standard chemotherapy. At 10 years, in patients treated with standard chemotherapy versus capecitabine, the RFS rates were 56% and 50%, respectively (hazard ratio [HR], 0.80; P = .03); breast cancer-specific survival rates were 88% and 82%, respectively (HR, 0.62; P = .03); and overall survival rates were 62% and 56%, respectively (HR, 0.84; P = .16). With longer follow-up, standard chemotherapy remains superior to capecitabine among hormone receptor-negative patients (HR, 0.66; P = .02), but not among hormone receptor-positive patients (HR, 0.89; P = .43). Overall, 43.9% of patients have died (13.1% from breast cancer, 16.4% from causes other than breast cancer, and 14.1% from unknown causes). Second nonbreast cancers occurred in 14.1% of patients. CONCLUSION: With longer follow-up, RFS remains superior for standard adjuvant chemotherapy versus capecitabine, especially in patients with hormone receptor-negative disease. Competing risks in this older population dilute overall survival benefits.

Proliferative potential and resistance to immune checkpoint blockade in lung cancer patients.

BACKGROUND: Resistance to immune checkpoint inhibitors (ICIs) has been linked to local immunosuppression independent of major ICI targets (e.g., PD-1). Clinical experience with response prediction based on PD-L1 expression suggests that other factors influence sensitivity to ICIs in non-small cell lung cancer (NSCLC) patients. METHODS: Tumor specimens from 120 NSCLC patients from 10 institutions were evaluated for PD-L1 expression by immunohistochemistry, and global proliferative profile by targeted RNA-seq. RESULTS: Cell proliferation, derived from the mean expression of 10 proliferation-associated genes (namely BUB1, CCNB2, CDK1, CDKN3, FOXM1, KIAA0101, MAD2L1, MELK, MKI67, and TOP2A), was identified as a marker of response to ICIs in NSCLC. Poorly, moderately, and highly proliferative tumors were somewhat equally represented in NSCLC, with tumors with the highest PD-L1 expression being more frequently moderately proliferative as compared to lesser levels of PD-L1 expression. Proliferation status had an impact on survival in patients with both PD-L1 positive and negative tumors. There was a significant survival advantage for moderately proliferative tumors compared to their combined highly/poorly counterparts (p = 0.021). Moderately proliferative PD-L1 positive tumors had a median survival of 14.6 months that was almost twice that of PD-L1 negative highly/poorly proliferative at 7.6 months (p = 0.028). Median survival in moderately proliferative PD-L1 negative tumors at 12.6 months was comparable to that of highly/poorly proliferative PD-L1 positive tumors at 11.5 months, but in both instances less than that of moderately proliferative PD-L1 positive tumors. Similar to survival, proliferation status has impact on disease control (DC) in patients with both PD-L1 positive and negative tumors. Patients with moderately versus those with poorly or highly proliferative tumors have a superior DC rate when combined with any classification schema used to score PD-L1 as a positive result (i.e., TPS ≥ 50% or ≥ 1%), and best displayed by a DC rate for moderately proliferative tumors of no less than 40% for any classification of PD-L1 as a negative result. While there is an over representation of moderately proliferative tumors as PD-L1 expression increases this does not account for the improved survival or higher disease control rates seen in PD-L1 negative tumors. CONCLUSIONS: Cell proliferation is potentially a new biomarker of response to ICIs in NSCLC and is applicable to PD-L1 negative tumors.

Implementing a personalized medicine program in a community health system.

The implementation of a de novo personalized medicine program in a rural community health system serving an underserved population is described. Focusing on the safe use of drugs impacted by genetic variations in the non-oncology setting, we first addressed drug-gene pairs designated by the US FDA in black-box warnings (codeine, clopidogrel, abacavir, carbamazepine). The program's first success was a policy change to remove codeine from the pediatric formulary, rather than a testing recommendation. Pilot studies were then conducted with primary care providers to get them familiar with pharmacogenetic testing, and a consultative outpatient clinic for patients was developed. The assessment, planning, implementation, challenges, successes and lessons learned are described.

Research Directions in the Clinical Implementation of Pharmacogenomics: An Overview of US Programs and Projects.

Response to a drug often differs widely among individual patients. This variability is frequently observed not only with respect to effective responses but also with adverse drug reactions. Matching patients to the drugs that are most likely to be effective and least likely to cause harm is the goal of effective therapeutics. Pharmacogenomics (PGx) holds the promise of precision medicine through elucidating the genetic determinants responsible for pharmacological outcomes and using them to guide drug selection and dosing. Here we survey the US landscape of research programs in PGx implementation, review current advances and clinical applications of PGx, summarize the obstacles that have hindered PGx implementation, and identify the critical knowledge gaps and possible studies needed to help to address them.

Comparison of HER2 status by fluorescence in situ hybridization and immunohistochemistry to predict benefit from dose escalation of adjuvant doxorubicin-based therapy in node-positive breast cancer patients.

PURPOSE: HER2 is a clinically important tumor marker in breast cancer; however, there is controversy regarding which method reliably measures HER2 status. We compared three HER2 laboratory methods: immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR), to predict disease-free survival (DFS) and overall survival (OS) after adjuvant doxorubicin-based therapy in node-positive breast cancer patients. METHODS: This is a Cancer and Leukemia Group B (CALGB) study, using 524 tumor blocks collected from breast cancer patients registered to clinical trial CALGB 8541. IHC employed CB11 and AO-11-854 monoclonal antibodies; FISH used PathVysion HER2 DNA Probe kit; PCR utilized differential PCR (D-PCR) methodology. RESULTS: Cases HER2 positive by IHC, FISH and D-PCR were 24%, 17%, and 18%, respectively. FISH and IHC were clearly related (kappa = 64.8%). All three methods demonstrated a similar relationship for DFS and OS. By any method, for patients with HER2-negative tumors, there was little or no effect of dose of adjuvant doxorubicin-based therapy. For patients with HER2-positive tumors, all three methods predicted a benefit from dose-intense (high-dose) compared with low- or moderate-dose adjuvant doxorubicin-based therapy. CONCLUSION: FISH is a reliable method to predict clinical outcome following adjuvant doxorubicin-based therapy for stage II breast cancer patients. There is a moderate level of concordance among the three methods (IHC, FISH, PCR). None of the methods is clearly superior. Although IHC-positive/FISH-positive tumors yielded the greatest interaction with dose of therapy in predicting outcome, no combination of assays tested was statistically superior.

The molecular portraits of breast tumors are conserved across microarray platforms.

BACKGROUND: Validation of a novel gene expression signature in independent data sets is a critical step in the development of a clinically useful test for cancer patient risk-stratification. However, validation is often unconvincing because the size of the test set is typically small. To overcome this problem we used publicly available breast cancer gene expression data sets and a novel approach to data fusion, in order to validate a new breast tumor intrinsic list. RESULTS: A 105-tumor training set containing 26 sample pairs was used to derive a new breast tumor intrinsic gene list. This intrinsic list contained 1300 genes and a proliferation signature that was not present in previous breast intrinsic gene sets. We tested this list as a survival predictor on a data set of 311 tumors compiled from three independent microarray studies that were fused into a single data set using Distance Weighted Discrimination. When the new intrinsic gene set was used to hierarchically cluster this combined test set, tumors were grouped into LumA, LumB, Basal-like, HER2+/ER-, and Normal Breast-like tumor subtypes that we demonstrated in previous datasets. These subtypes were associated with significant differences in Relapse-Free and Overall Survival. Multivariate Cox analysis of the combined test set showed that the intrinsic subtype classifications added significant prognostic information that was independent of standard clinical predictors. From the combined test set, we developed an objective and unchanging classifier based upon five intrinsic subtype mean expression profiles (i.e. centroids), which is designed for single sample predictions (SSP). The SSP approach was applied to two additional independent data sets and consistently predicted survival in both systemically treated and untreated patient groups. CONCLUSION: This study validates the "breast tumor intrinsic" subtype classification as an objective means of tumor classification that should be translated into a clinical assay for further retrospective and prospective validation. In addition, our method of combining existing data sets can be used to robustly validate the potential clinical value of any new gene expression profile.

Molecular subtypes of breast cancer in relation to paclitaxel response and outcomes in women with metastatic disease: results from CALGB 9342.

INTRODUCTION: The response to paclitaxel varies widely in metastatic breast cancer. We analyzed data from CALGB 9342, which tested three doses of paclitaxel in women with advanced disease, to determine whether response and outcomes differed according to HER2, hormone receptor, and p53 status. METHODS: Among 474 women randomly assigned to paclitaxel at a dose of 175, 210, or 250 mg/m2, adequate primary tumor tissue was available from 175. Immunohistochemistry with two antibodies and fluorescence in situ hybridization were performed to evaluate HER2 status; p53 status was determined by immunohistochemistry and sequencing. Hormone receptor status was obtained from pathology reports. RESULTS: Objective response rate was not associated with HER2 or p53 status. There was a trend toward a shorter median time to treatment failure among women with HER2-positive tumors (2.3 versus 4.2 months; P = 0.067). HER2 status was not related to overall survival (OS). Hormone receptor expression was not associated with differences in response but was associated with longer OS (P = 0.003). In contrast, women with p53 over-expression had significantly shorter OS than those without p53 over-expression (11.5 versus 14.4 months; P = 0.002). In addition, triple negative tumors were more frequent in African-American than in Caucasian patients, and were associated with a significant reduction in OS (8.7 versus 12.9 months; P = 0.008). CONCLUSION: None of the biomarkers was predictive of treatment response in women with metastatic breast cancer; however, survival differed according to hormone receptor and p53 status. Triple negative tumors were more frequent in African-American patients and were associated with a shorter survival.

Response and cardiac toxicity of trastuzumab given in conjunction with weekly paclitaxel after doxorubicin/cyclophosphamide.

BACKGROUND: Adjuvant trastuzumab improves relapse-free survival in HER2-overexpressing breast cancer but is associated with cardiac toxicity. This phase II study was undertaken to determine the neoadjuvant clinical and pathologic response rate and the acute and chronic cardiac toxicity of trastuzumab given with weekly paclitaxel after AC (doxorubicin/cyclophosphamide). PATIENTS AND METHODS: Fifty-two women with newly diagnosed, stage II-IV, HER2-overexpressing breast cancer received AC for 4 cycles, followed by weekly TP (paclitaxel/trastuzumab) for 12 weeks, neoadjuvantly or adjuvantly, followed by 40 weeks of adjuvant trastuzumab. RESULTS: Congestive heart failure occurred in 4% of patients (95% confidence interval [CI], 0.5%-13.2%). Asymptomatic left ventricular ejection fraction (LVEF) decreases to < 50% occurred in 21% of patients (95% CI, 11.1%-34.7%); all but 1 recovered by 1.5 years. Median LVEF decreased progressively during therapy from 65% before therapy (95% CI, 63%-66%) to 62% after AC (95% CI, 59%-64%) and 58% after AC-TP (95% CI, 56%-64%; P < 0.01 for each decrease). The decrease in LVEF persisted 1.5 years after study entry at 57% (95% CI, 54%-60%), although all but 1 of the most severe decreases to < 50% recovered to normal. Clinical response rate among 37 patients treated neoadjuvantly was 86%, and the pathologic complete response rate was 19% (95% CI, 8%-35.2%). Because of withdrawals for toxicity, refractory disease, and patient preference, only 35% of patients completed the entire regimen. CONCLUSION: In this study, the AC-TP regimen resulted in a high clinical but moderate pathologic response rate, and although asymptomatic cardiac systolic dysfunction was common, most of the severe decreases recovered over time.