Citations

Abstract Aromatase (CYP19) is a critical enzyme in estrogen biosynthesis and aromatase inhibitors (AI) are employed widely for endocrine therapy in postmenopausal women with breast cancer. We hypothesized that single nucleotide polymorphisms (SNPs) in the CYP19 gene may alter the effectiveness of AI therapy in the neoadjuvant setting. Genomic DNA was obtained for sequencing from 52 women pre-AI and post-AI treatment in this setting. Additionally, genomic DNA obtained from 82 samples of breast cancer and 19 samples of normal breast tissue was subjected to resequencing. No differences in CYP19 sequence were observed between tumor and germ-line DNA in the same patient. A total of 48 SNPs were identified including 4 novel SNPs when compared with previous resequencing data. For genotype-phenotype association studies, we determined the levels of aromatase activity, estrone, estradiol, and tumor size in patients pre-AI and post-AI treatment. We defined two tightly linked SNPs (rs6493497 and rs7176005 in the 5'-flanking region of CYP19 exon 1.1) that were significantly associated with a greater change in aromatase activity after AI treatment. In a follow-up study of 200 women with early-stage breast cancer who were treated with adjuvant anastrozole, these same two SNPs were also associated with higher plasma estradiol levels in patients pre-AI and post-AI treatment. Electrophoretic mobility shift and reporter gene assays confirmed likely functional effects of these two SNPs on transcription of CYP19. Our findings indicate that two common genetic polymorphisms in the aromatase gene CYP19 vary the response of breast cancer patients to aromatase inhibitors. Cancer Res; 70(1); 319–28

Sensitivity analysis is an important statistical technique that assesses whether the results of phase III trials are robust and likely to be generalizable. Until recently, sensitivity analyses were rarely included in phase III trials, and they remain poorly understood by many oncologists. Sensitivity analyses are critical to understanding the strength of conclusions made in the primary analysis of a late-stage clinical trial. They examine the influence of protocol design errors, unintended biases, deviations from assumptions underlying statistical models, and any unanticipated treatment delivery or practice patterns on trial results. In trials with complex or subjective end points, they also allow an understanding of the extent to which a positive outcome is driven by a single, possibly subjective, and therefore biased, element of an end point. The purposes of this article are to explain how sensitivity analyses are performed, to discuss areas of a clinical trial where sensitivity analyses should focus, and to illuminate the importance of this technique in the rigorous evaluation of late-stage clinical trial data, using specific examples. This article focuses on late-stage trials that use progression-free survival or time to progression as their primary end point, because sensitivity analyses are particularly important in these cases for which the end point is potentially subject to bias. Three sources of potential bias are explored: assessment time, symptomatic (ie, nonradiologic) disease progression, and missing data. For each source of potential bias, case studies are presented to highlight the role that sensitivity analyses play in determining whether the trial's conclusions are robust.

Purpose For nearly two decades, multiple retrospective reports, small prospective studies, and meta-analyses have arrived at conflicting results regarding the value of timing surgical intervention for breast cancer on the basis of menstrual cycle phase. We present the results of a multi–cooperative group, prospective, observational trial of menstrual cycle phase and outcome after breast cancer surgery, led by the North Central Cancer Treatment Group (NCCTG) in collaboration with the National Surgical Adjuvant Breast and Bowel Project (NSABP) and the International Breast Cancer Study Group (IBCSG). Patients and Methods Premenopausal women age 18 to 55 years, who were interviewed for menstrual history and who were surgically treated for stages I to II breast cancer, had serum drawn within 1 day of surgery for estradiol, progesterone, and luteinizing hormone levels. Menstrual history and hormone levels were used to determine menstrual phase: luteal, follicular, and other. Disease-free survival (DFS) and overall survival (OS) rates were determined by Kaplan-Meier method and were compared by using the log-rank test and Cox proportional hazard modeling. Results Of 1,118 women initially enrolled, 834 women comprised the study cohort: 230 (28%) in luteal phase; 363 (44%) in follicular phase; and 241 grouped as other. During a median follow-up of 6.6 years, and in analysis that accounted for nodal disease, estrogen receptor status, adjuvant radiation therapy or chemotherapy, neither DFS nor OS differed with respect to menstrual phase. The 5-year DFS rates were 82.7%, 82.1%, and 79.2% for follicular, luteal, or other phases, respectively. Corresponding OS survival rates were 91.9%, 92.2%, and 91.8%, respectively. Conclusion When menstrual cycle phases were strictly defined, neither DFS nor OS differed between women who underwent surgery during the follicular phase versus the luteal phase. Nearly 30% of the patients did not meet criteria for either follicular- or luteal-phase categories.

Purpose To assess whether trastuzumab (H) with radiotherapy (RT) increases adverse events (AEs) after breast-conserving surgery or mastectomy. Patients and Methods Patients with early-stage resected human epidermal growth factor receptor 2 (HER-2) –positive breast cancer (BC) were randomly assigned to doxorubicin (A) and cyclophosphamide (C), followed by weekly paclitaxel (T; AC-T-H or AC-TH-H). RT criteria (with or without nodal RT) were postlumpectomy breast or (optional) postmastectomy chest wall. RT of internal mammary nodes was prohibited. RT commenced within 5 weeks after T, concurrently with H. Analysis included 1,503 irradiated patients for RT-associated AEs across treatment arms. Rates of cardiac events (CEs) with and without RT were compared within arms. Results No significant differences among arms were found in incidence of acute skin reaction, pneumonitis, dyspnea, cough, dysphagia, or neutropenia. A significant difference occurred in incidence of leukopenia, with higher rates for AC-T-H versus AC-T (odds ratio = 1.89; 95% CI, 1.25 to 2.88). At a median follow-up of 3.7 years (range, 0 to 6.5 years), RT with H did not increase relative frequency of CEs regardless of treatment side. The cumulative incidence of CEs with AC-T-H was 2.7% with or without RT. With AC-TH-H, the cumulative incidence was 1.7% v 5.9% with or without RT, respectively. Conclusion Concurrent adjuvant RT and H for early-stage BC was not associated with increased acute AEs. Further follow-up is required to assess late AEs.

Abstract Purpose: Genetic variation in cytochrome P450 2D6 (CYP2D6) and the gene expression ratio of the homeobox 13 (HOXB13) to interleukin-17B receptor (IL17BR) are associated with tamoxifen resistance. We sought to determine the combined effect of inherited (CYP2D6) and somatic (HOXB13/IL17BR) gene variation in tamoxifen-treated breast cancer. Experimental Design: Retrospective analysis of women with node-negative breast cancer randomized to receive 5 years of tamoxifen (North Central Cancer Treatment Group 89-30-52). CYP2D6 metabolism (extensive or decreased) was based on CYP2D6*4 genotype and presence/absence of a CYP2D6 inhibitor. Reverse transcription-PCR profiles for HOXB13 and IL17BR and the cut point separating patients into high- and low-risk categories according to disease-free survival (DFS) were used. A risk factor (CYP2D6:HOXB13/IL17BR) representing the four categories of combining CYP2D6 metabolism (extensive or decreased) and HOXB13/IL17BR (low or high) was created. The association between CYP2D6:HOXB13/IL17BR and DFS and overall survival (OS) was assessed using the log-rank test and proportional hazards modeling. Results: CYP2D6 metabolism and HOXB13/IL17BR gene ratio was available in 110 of 160 (69%) patients. The combined CYP2D6:HOXB13/IL17BR risk factor was significantly associated with DFS (log-rank P = 0.004) and OS (P = 0.009). Relative to women with extensive CYP2D6 metabolism and low HOXB13/IL17BR, those with either decreased metabolism or a high HOXB13/IL17BR ratio had significantly worse OS (adjusted hazard ratio, 2.41; 95% confidence interval, 1.08-5.37; P = 0.031), whereas women with both decreased metabolism and high HOXB13/IL17BR ratio had the shortest survival (adjusted hazard ratio, 3.15; 95% CI, 1.17-8.52; P = 0.024). Conclusions: An index composed of inherited (CYP2D6) and tumor (HOXB13/IL17BR) gene variation identifies patients with varying degrees of resistance to tamoxifen.

Abstract Metaplastic breast carcinoma, a rare tumor composed of adenocarcinomatous and nonglandular growth patterns, is characterized by a propensity for distant metastases and resistance to standard anticancer therapies. We sought confirmation that this tumor is a basal-like breast cancer, expressing epidermal growth factor receptor (EGFR) and stem cell factor receptor (KIT). EGFR activating mutations and high copy number (associated with response to tyrosine kinase inhibitor gefitinib) and KIT activating mutations (associated with imatinib sensitivity) were then investigated. Seventy-seven metaplastic cases were identified (1976-2006); 38 with tumor blocks available underwent pathologic confirmation before EGFR and KIT immunohistochemical analyses. A tissue microarray of malignant glandular and metaplastic elements was constructed and analyzed immunohistochemically for cytokeratin 5/6, estrogen receptor, progesterone receptor, and p63, and by fluorescence in situ hybridization for EGFR and HER-2/neu. DNA isolated from individual elements was assessed for EGFR and KIT activating mutations. All assessable cases were negative for estrogen receptor, progesterone receptor, and (except one) HER2. The majority were positive for cytokeratin 5/6 (58%), p63 (59%), and EGFR overexpression (66%); 24% were KIT positive. No EGFR or KIT activating mutations were present; 26% of the primary metaplastic breast carcinomas were fluorescence in situ hybridization-positive, displaying high EGFR copy number secondary to aneusomy (22%) and amplification (4%). We report here that metaplastic breast carcinoma is a basal-like breast cancer lacking EGFR and KIT activating mutations but exhibiting high EGFR copy number (primarily via aneusomy), suggesting that EGFR tyrosine kinase inhibitors should be evaluated in this molecular subset of breast carcinomas. [Mol Cancer Ther 2008;7(4):944–51]

Purpose To assess cardiac safety and potential cardiac risk factors associated with trastuzumab in the NCCTG N9831 Intergroup adjuvant breast cancer trial. Patients and Methods Patients with HER2-positive operable breast cancer were randomly assigned to doxorubicin plus cyclophosphamide (AC) followed by either weekly paclitaxel (arm A); paclitaxel then trastuzumab (arm B); or paclitaxel plus trastuzumab then trastuzumab alone (arm C). Left ventricular ejection fraction (LVEF) was evaluated at registration and 3, 6, 9, and 18 to 21 months. Results Of 2,992 patients completing AC, 5.0% had LVEF decreases disallowing trastuzumab (decrease below normal: 2.4%, decrease > 15%: 2.6%). There were 1,944 patients with satisfactory or no LVEF evaluation who proceeded to post-AC therapy. Cardiac events (congestive heart failure [CHF] or cardiac death [CD]): arm A, n = 3 (2 CHF, 1 CD); arm B, n = 19 (18 CHF, 1 CD); arm C, n = 19 (all CHF); 3-year cumulative incidence: 0.3%, 2.8%, and 3.3%, respectively. Cardiac function improved in most CHF cases following trastuzumab discontinuation and cardiac medication. Factors associated with increased risk of a cardiac event in arms B and C: older age (P < .003), prior/current antihypertensive agents (P = .005), and lower registration LVEF (P = .033). Incidence of asymptomatic LVEF decreases requiring holding trastuzumab was 8% to 10%; LVEF recovered and trastuzumab was restarted in approximately 50%. Conclusion The cumulative incidence of post-AC cardiac events at 3 years was higher in the trastuzumab-containing arms versus the control arm, but by less than 4%. Older age, lower registration LVEF, and antihypertensive medications are associated with increased risk of cardiac dysfunction in patients receiving trastuzumab following AC.

Purpose Objective tumor response rates observed in phase II trials for metastatic melanoma have historically not provided a reliable indicator of meaningful survival benefits. To facilitate using overall survival (OS) or progression-free survival (PFS) as an endpoint for future phase II trials, we evaluated historical data from cooperative group phase II trials to attempt to develop benchmarks for OS and PFS as reference points for future phase II trials. Patients and Methods Individual-level and trial-level data were obtained for patients enrolled onto 42 phase II trials (70 trial arms) that completed accrual in the years 1975 through 2005 and conducted by Southwest Oncology Group, Eastern Cooperative Oncology Group, Cancer and Leukemia Group B, North Central Cancer Treatment Group, and the Clinical Trials Group of the National Cancer Institute of Canada. Univariate and multivariate analyses were performed to identify prognostic variables, and between-trial(-arm) variability in 1-year OS rates and 6-month PFS rates were examined. Results Statistically significant individual-level and trial-level prognostic factors found in a multivariate survival analysis for OS were performance status, presence of visceral disease, sex, and whether the trial excluded patients with brain metastases. Performance status, sex, and age were statistically significant prognostic factors for PFS. Controlling for these prognostic variables essentially eliminated between-trial variability in 1-year OS rates but not in 6-month PFS rates. Conclusion Benchmarks are provided for 1-year OS or OS curves that make use of the distribution of prognostic factors of the patients in the phase II trial. A similar benchmark for 6-month PFS is provided, but its use is more problematic because of residual between-trial variation in this endpoint.