Abstract P1-03-04: Molecular subtyping of androgen receptor-positive patients using gene expression profiles

Breast cancer is a heterogeneous disease, and unsupervised clustering approaches using gene expression data have identified 3-6 distinct subtypes of triple negative breast cancer (TNBC). A genomically and clinically distinct subtype of TNBC is referred to as LAR (Luminal Androgen Receptor). Tumors with this subtype typically express high levels of the AR and exhibit alterations within genes involved in the PI3K pathway (e.g. PIK3CA mutations). Prospective studies are underway using drugs that target the AR alone or in combination with PI3K and CDK 4/6 inhibitors. Given the importance of accurately identifying this subtype, we sought to develop an online tool that uses submitted gene expression data to confidently characterize LAR samples by corroborating the classification with previously published clustering approaches.

Methods: We have investigated TNBC RNA-Seq data from The Cancer Genome Atlas (TCGA) breast cancer study (N=123 samples) by cluster analysis. Analysis of the average silhouette width in both biased and unbiased K-means clustering approaches demonstrated LAR and basal as two distinct and significant clusters. A shrunken centroid model of 426 differentially expressed genes, named as CABAL (Clustering Among BAsal and Luminal androgen receptor), was constructed by comparing LAR and basal subtypes.

Results: We applied the CABAL model to classify the four TNBC microarray datasets that were previously used in clustering experiments as well as an independent RNA-Seq data cohort. Non-negative matrix factorization (NMF) and fuzzy clustering were applied to the samples (N=1046). Clustering similarity among the methods was assessed with the adjusted rand index, and CABAL demonstrated significant similarity with both fuzzy and NMF clustering methods. Similarly, hierarchical clustering analysis performed on the pooled cohort of 1046 samples recapitulated the CABAL classification with an area under the receiver operating curve of 0.91.

Conclusions: Confident and robust identification of samples with the LAR phenotype is paramount in the assessment of clinical associations and therapeutic efficacy. To facilitate LAR identification, we have provided a web-based prediction tool of the CABAL classification, integrated with the NMF and fuzzy clustering results to identify candidate LAR samples. The end user is provided with the pair-wise adjusted rand indexes, thus reinforcing in the clustering characterizations. Further, our online LAR depiction tool provides a set of graphical and tabular summaries, which will be illustrated, while providing additional molecular characterizations of the PAM50 and Metabric classifications. The availability of this tool could advance the genomic research and treatment of TNBC patients.

Citation Format: Thompson KJ, Alaparthi T, Sinnwell JP, Carlson EE, Tang X, Bockol M, Vedell PT, Ingle JN, Suman V, Weinshilboum RM, Wang L, Boughey JC, Kalari KR, Goetz MP. Molecular subtyping of androgen receptor-positive patients using gene expression profiles [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-03-04.

Abstract PD8-03: ESR1 gene fusions drive endocrine therapy resistance and metastasis in breast cancer

Background. Dysregulation of the estrogen receptor gene (ESR1) is an established mechanism of inducing endocrine therapy resistance. We previously discovered a chromosomal translocation event generating an estrogen receptor gene fused in-frame to C-terminal sequences of YAP1 (ESR1-YAP1) that contributed to endocrine therapy resistance in estrogen receptor positive (ER+) breast cancer models. This study compares functional, transcriptional, and pharmacological properties of additional ESR1 gene fusion events of both early stage (ESR1-NOP2) late stage (ESR1-YAP1 and ESR1-PCDH11x) breast cancers to gain a better understanding of therapeutic resistance and metastasis. Understanding the role of ESR1 fusions in inducing metastasis is critical, since the primary cause of death in breast cancer patients is through metastasis to distant sites.

Methods. RNA-seq screens identified ESR1 fusions from early and late stage, endocrine therapy resistant breast tumor samples. Functional experiments were conducted using ER+ breast cancer cell lines, xenograft, and PDX models to test the ability of ESR1 fusions to induce therapeutic resistance and metastasis. ChIP-seq and RNA-seq were performed to examine transcriptional properties and differential gene expression induced by the fusions which directed subsequent pharmacological experiments with a CDK4/6 inhibitor.

Results. ESR1-YAP1 and ESR1-PCDH11x promoted estrogen-independent and fulvestrant-resistant growth in vitro and induced greater tumor growth and increased metastatic capacity to the lungs of xenografted mice. In contrast, the ESR1-NOP2 fusion was sensitive to low estrogen conditions in vitro, and did not promote tumor growth. RNA-seq profiling revealed E2F targets pathway as the most highly enriched pathway induced by the ESR1 fusions. IHC revealed higher levels of pRb in ESR1-YAP1 and ESR1-PCDH11x xenograft tumors and subsequent CDK4/6 inhibition completely blocked tumor growth in an ESR1-YAP1 PDX model. Integrating RNA-seq with ChIP-seq data, we discovered a set of EMT and metastasis genes bound by all ESR1 fusions and WT-ER, but whose expression was strongly and uniquely up-regulated only by the ESR1-YAP1 and ESR1-PCDH11x fusions. These studies also revealed gained sites bound only by the ESR1-YAP1 and ESR1-PCDH11x fusions, not bound by WT-ER nor ESR1-NOP2. Genes mapping to these sites have a role in metastatic biology and were highly up-regulated by the YAP1 and PCDH11x fusions, potentially mediated by long range transcriptional activation.

Conclusion. ESR1-YAP1 and ESR1-PCDH11x are driver fusions that occur in drug-resistant, advanced stage breast cancer and are a new class of recurrent somatic mutation that can cause acquired endocrine therapy resistance, yet can be treated with CDK4/6 inhibition. These driver fusions also confer increased metastatic ability through their ability to drive expression of genes that contribute to EMT and metastasis. In contrast, ESR1-NOP2 did not produce functional protein and appears to be a passenger event. These studies may provide pre-clinical rationale for targeting ESR1 translocated breast tumors, since the presence of an ESR1 driver fusion places a patient in a therapeutic category where none of the currently available endocrine therapies are likely to be effective.

Citation Format: Lei JT, Shao J, Zhang J, Iglesia M, Chan DW, Cao J, Anurag M, Singh P, Haricharan S, Kavuri SM, Matsunuma R, Schmidt C, Kosaka Y, Crowder R, Hoog J, Phommaly C, Goncalves R, Ramalho S, Rodrigues-Peres RM, Lai W-C, Hampton O, Rogers A, Tobias E, Parikh P, Davies S, Ma C, Suman V, Hunt K, Watson M, Hoadley KA, Thompson A, Perou CM, Creighton CJ, Maher C, Ellis MJ. ESR1 gene fusions drive endocrine therapy resistance and metastasis in breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD8-03.

Abstract PD2-03: Recurrent functionally diverse in-frame ESR1 gene fusions drive endocrine resistance in breast cancer

Background. We previously reported an alternative ESR1 somatic gain-of-function chromosomal translocation event in a patient presenting with aggressive, endocrine therapy resistant estrogen receptor (ER) positive disease, producing an in-frame fusion gene consisting of N-terminal ESR1 and the C-terminus of the Hippo pathway coactivator YAP1 (ESR1-YAP1). We recently identified another ESR1 fusion through RNA sequencing (RNA-seq) in advanced stage ER+ disease from a chest wall recurrence in a male patient that was refractory to multiple lines of treatment. Two examples of fusions discovered in primary breast cancer samples include ESR1 fused in-frame to C-terminal sequences from NOP2 (ESR1-NOP2), identified in a resistant cohort from a RNA-seq screen focused on 81 primary breast cancers from aromatase inhibitor clinical trials, and a second ESR1 fusion, fused in-frame to the entire coding sequence of POLH (ESR1-POLH), that was identified from RNA-seq analysis of 728 Cancer Genome Atlas breast samples. This current study extends our previous characterization of ESR1-YAP1 by comparing functional and pharmacological properties of these three additional ESR1 gene fusion events of both early stage and advanced breast cancers.

Methods. In vitro and in vivo experiments were conducted to test ESR1 fusions to induce therapeutic resistance, and metastasis. The transcriptional and binding properties of each fusion was also examined. Pharmacological inhibition with Palbociclib, a cyclin-dependent kinase 4/6 inhibitor, was utilized to assess drug sensitivity in ESR1 fusion containing breast cancer cells and in a patient derived xenograft (PDX) model expressing ESR1-YAP1 (WHIM18).

Results. The YAP1 and PCDH11x fusions conferred estrogen-independent and fulvestrant-resistant growth. Immunohistochemistry revealed significantly higher numbers of ER+ cells in lungs of mice xenografted with T47D cells expressing the YAP1 and PCDH11x fusions compared to YFP control, NOP2 and POLH fusions. Results from ChIP-seq and microarray studies suggest that these two fusions promote proliferation and metastasis through genomic action by binding estrogen response elements (ERE) and subsequent gene activation. We thereby define these fusions as “canonical” fusions compared to “non-canonical” NOP2 and POLH fusions, which demonstrated dramatically decreased genomic binding ability. The non-canonical fusions induced genes associated with basal-like breast cancer and promoted HER2, EGFR, and MAPK gene expression signatures in contrast to genes associated with cell cycle/proliferation induced by canonical fusions. The proliferative ability of canonical fusion-containing ER+ cells was inhibited by Palbociclib in a dose-dependent manner. In vivo WHIM18 tumors in mice fed with Palbociclib-containing chow demonstrated significantly reduced tumor volume, growth rate, and weight compared to tumors in mice on control chow.

Conclusions. In-frame ERE activating canonical fusions occur in end-stage drug resistant advanced breast cancer and can be added to ESR1 point mutations as a class of recurrent somatic mutation that may cause acquired resistance. Growth induced by these fusions can be antagonized by Palbociclib and is potentially clinically helpful.

Citation Format: Lei JT, Shao J, Zhang J, Iglesia M, Cao J, Chan DW, He X, Kosaka Y, Schmidt C, Matsunuma R, Haricharan S, Crowder R, Hoog J, Phommaly C, Goncalves R, Ramalho S, Lai W-C, Hampton O, Rogers A, Tobias E, Parikh P, Davies S, Ma C, Suman V, Hunt K, Watson M, Hoadley KA, Thompson A, Chen X, Perou CM, Creighton CJ, Maher C, Ellis MJ. Recurrent functionally diverse in-frame ESR1 gene fusions drive endocrine resistance in breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD2-03.

Abstract P2-02-03: Optimized prediction of deleterious missense mutations in BRCA1 and BRCA2 genes

Approximately 15% of genetic screens for mutations in BRCA1 and BRCA2 identify Variants of Uncertain Significance (VUS). Primarily missense mutations, VUS are often difficult to interpret, leading to either uncertainty in how to properly counsel a patient or an unnecessary prophylactic surgery. Given the paucity of data for which missenses are classified as truly pathogenic, computational deleterious missense prediction (DMP) algorithms are used to predict whether a mutation is likely deleterious or neutral. Accuracy of DMPs can vary considerably and have only been calibrated on a relatively small number of missense mutations of demonstrable effect on protein function. In this study, the performance of 41 different DMPs was compared to functional data from 455 functionally characterized missense variants in BRCA1 and BRCA2. New optimized thresholds for classifying missense mutations as deleterious are presented for several existing models as well as a newly derived naïve voting method (NVM). The areas under the curve estimates for the NVM approach are between 0.889-0.922, much higher than previous methods. We estimate that the overall pathogenic potential of missense variants to be 6.8% for BRCA1 and 3.2% of BRCA2, but can be as high as 50% depending on protein location. Overall these results provide key insights into how to predict deleterious missense mutations in BRCA1 and BRCA2.

Citation Format: Hart SN, Hoskin T, Shimelis H, Feng B, Lindor NM, Monteiro A, Iversen E, Goldgar DE, Suman V, Couch FJ. Optimized prediction of deleterious missense mutations in BRCA1 and BRCA2 genes [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-02-03.

Abstract P5-04-01: ERβ elicits tumor suppressive effects in triple negative breast cancer through the induction of cystatins and suppression of TGFβ signaling

Background: Triple negative breast cancer (TNBC) accounts for approximately 20% of all breast cancer diagnoses. Clinical management of TNBC is limited to surgery, chemotherapy and radiation due to lack of estrogen receptor alpha and HER2 expression. Recently, we have shown that approximately 40% of TNBCs express estrogen receptor beta (ERβ) and have begun to explore the possibility that this receptor could be utilized as a novel therapeutic target for this disease.

Methods: To examine the biological functions of ERβ in TNBC, novel ERβ expressing TN cell lines (MDA-MB-231 and Hs578T) were developed. In vitro experiments were employed to determine alterations in the global gene expression profiles, biological pathways, proliferation rates, and cell cycle progression following estrogen or ERβ-specific agonist treatment. Cell line xenografts were also established in athymic ovariectomized nude mice to examine tumoral responses to ERβ targeting agents and to investigate gene and protein expression patterns as well as potential serum biomarkers indicative of therapeutic response. Additionally, using the resources of the Mayo Clinic Breast Cancer Genome Guided Therapy Study (BEAUTY), we have identified, and begun to analyze, ERβ+ and ERβ- patient derived xenografts (PDX) established from women with TNBC.

Results: Our studies have revealed that both estrogen and multiple ERβ-specific agonists elicit significant anti-proliferative effects in ERβ+ TNBC cells primarily through a G1/S phase cell cycle arrest. These anti-proliferative effects appear to be mediated by cystatins, a family of small secreted cysteine protease inhibitors which are highly induced following estrogen and ERβ-specific agonist treatment. Conditioned media isolated from estrogen or ERβ-specific agonist treated cells decreased the proliferation rates of multiple non-ERβ expressing cell lines; effects that were completely reversed when cystatins were depleted from the media. In addition, we have shown that activation of ERβ, and the subsequent induction of cystatin gene expression, leads to suppression of canonical TGFβ signaling through multiple mechanisms including suppression of TGFβR2 expression, induction of Smad7 expression and blockade of TGFβ ligand-mediated activation of this pathway both in vitro and in vivo. Finally, ERβ+ TNBC PDXs exhibit significantly decreased tumor growth rates in estrogen-treated mice compared to ERβ- TN breast tumors.

Conclusions: Our in vitro and in vivo data show that estrogen and ERβ-specific agonists elicit anti-cancer effects in ERβ+ TNBC. These effects appear to be mediated, in part, by cystatins through their inhibitory effects on canonical TGFB signaling, a pathway known to drive TNBC progression. Importantly, these data lay the foundation for studies aimed at examining the ability to therapeutically target ERβ in TNBC patients.

Citation Format: Reese J, Bruinsma E, Subramaniam M, Suman V, Pitel K, Kalari K, Yu J, Wang L, Goetz M, Ingle J, Hawse J. ERβ elicits tumor suppressive effects in triple negative breast cancer through the induction of cystatins and suppression of TGFβ signaling. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-04-01.

Analysis of hydrological trend for radioactivity content in bore-hole water samples using wavelet based denoising

A wavelet transform based denoising methodology has been applied to detect the presence of any discernable trend in (137)Cs and (90)Sr activity levels in bore-hole water samples collected four times a year over a period of eight years, from 2002 to 2009, in the vicinity of typical nuclear facilities inside the restricted access zones. The conventional non-parametric methods viz., Mann-Kendall and Spearman rho, along with linear regression when applied for detecting the linear trend in the time series data do not yield results conclusive for trend detection with a confidence of 95% for most of the samples. The stationary wavelet based hard thresholding data pruning method with Haar as the analyzing wavelet was applied to remove the noise present in the same data. Results indicate that confidence interval of the established trend has significantly improved after pre-processing to more than 98% compared to the conventional non-parametric methods when applied to direct measurements.

Abstract PD10-08: Venlafaxine inhibits the CYP2D6 mediated metabolic activation of tamoxifen: Results of a prospective multicenter study: (NCT00667121)

Background: CYP2D6 is the rate limiting enzyme responsible for the metabolic activation of tamoxifen (tam) to endoxifen. Compared to CYP2D6 poor metabolizers (PM), tam-treated CYP2D6 extensive metabolizers (EM) have higher endoxifen concentrations, more vasomotor symptoms (Goetz, MP J Clin Oncol 2005), and are more likely to discontinue tam (Rae, JM 2009. Pharmacogenomics J). Additionally, higher endoxifen concentrations are associated with a stepwise increase in tam side-effects (Lorizio, W Breast Cancer Res Treat 2012). The data regarding CYP2D6 genotype and recurrence is mixed. Venlafaxine is a weak CYP2D6 inhibitor not known to alter tam pharmacokinetics (PK) and commonly recommended for tam induced hot flashes. We conducted a multicenter pharmacological study to determine whether venlafaxine altered the PK of tam and to determine the distribution of CYP2D6 genotypes in this population

Methods: Women taking tam for at least 4 weeks and for whom venlafaxine was recommended for the treatment of hot flashes were eligible. Blood samples were collected prior to and 8–16 weeks following initiation of venlafaxine for steady state tam and metabolites. Genotyping was performed for alleles associated with no (PM; *3, *4, *5,*6); reduced (intermediate, IM; *10, 17 and *41); and ultra-rapid (UM; *1×2) metabolism. Power calculations demonstrated that 17 patients with paired samples were required (two-sided alpha=0.05 t-test, 90% power) to detect a 25% change in endoxifen levels after at least 8 weeks of concurrent treatment.

Results: 30 women (median age 48.5) initiated venlafaxine. CYP2D6 genotypes were within Hardy Weinberg Equilibrium (HWE). CYP2D6 UM allele frequency (6.7%) was higher while CYP2D6 *4 (13.3%) was lower than expected compared to an unselected population (0.5 and 21% respectively; Sachse Am. J. Hum. Genet. 1997), resulting in the absence of CYP2D6 PM/PM. Mean (min/max) baseline endoxifen concentrations (8.73; 1.5–20.5 ng/ml) were correlated with CYP2D6 phenotype as follows: intermediate (EM/PM, PM/IM): 6.8 (1.5–11.2); extensive (EM/EM, EM/IM): 9.4 (1.5–20.5) and ultra-rapid (UM/EM: 11.0; 7.8–14) (r2 = 0.35 p = 0.05). In patients with paired samples (n = 20), venlafaxine resulted in a 23% decrease in endoxifen (−2.06 ng/ml; 95% CI −0.69 to −3.04; p = 0.004), but not tam, NDMT, or 4HT concentrations. Following initiation of venlafaxine, CYP2D6 genotype was no longer associated with endoxifen concentrations (r2 = 0.28 p = 0.23). For women with reduced CYP2D6 metabolism [EM/PM (n = 9) or PM/IM (n = 1)], venlafaxine lowered endoxifen concentrations (−2.98 ng/ml) to a level (5.41 ng/ml) reported to be associated with a higher risk of recurrence in adjuvant tam treated patients (Madlensky, L Clin Pharmacol Ther 2011).

Conclusions: In this study, women with tam-induced vasomotor symptoms requiring venlafaxine were comprised predominantly of CYP2D6 EM and UM metabolizers. Venlafaxine significantly decreased endoxifen concentrations. Although the optimal concentration of endoxifen is unknown, given prior data linking low endoxifen concentrations with recurrence, venlafaxine should be used with caution in tam treated patients. (Supported by R01CA133049)

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD10-08.

PD01-06: Endoxifen Exhibits Potent Anti-Tumor Activity and Regulates Different Genes Than Tamoxifen in an Aromatase Expressing MCF7 Model Resistant to Letrozole

Background: First in human studies of Z-endoxifen hydrochloride (E), the active metabolite of tamoxifen (T), are underway in metastatic breast cancer (BC). Previous data have demonstrated the superiority of aromatase inhibitors (AI's) over T in estrogen receptor (ER) + BC. Using an in vivo aromatase expressing model (MCF7/AC1), we compared the antitumor activity of E with T and Letrozole (L), as well as the antitumor activity and global gene expression changes of E with T in an L-resistant model.

Methods: MCF7/AC1 tumors were stimulated with androstenedione. Once tumor size reached 300 mm3, mice (30/group) were randomly assigned to one of five treatment groups: control (daily, po), T (500 μg/day, sc), endoxifen 25 mg/kg/day p.o.(LDE) endoxifen 75 mg/kg/day p.o. (HDE) or letrozole, 10 μg/day s.c for 4 weeks. Tumors were harvested from control, T, and E groups while the L group continued treatment until the development of resistance defined as an increase in tumor volume of at least 300% from day 1. Mice with L-resistant tumors were randomly assigned to T (n=4) or E (n=5) for 4 weeks and then sacrificed. Gene expression in L-resistant tumors was quantified using Affymetrix U133+2 and changes in gene expression profiles [comparing T and E with L-resistant (n=3)] were analyzed. Genes identified as significantly different were confirmed by real-time RT-PCR assays.

Results: At the 4 week time point, both doses of E and L resulted in greater anti-tumor activity than control (Wilcoxon rank sum test: all p < 0.0001); however, tumor burden did not differ between T and control (p=0.095). HDE resulted in significantly less tumor burden than T (p=0.002) but was similar to L. In mice that continued on L, resistance developed at 24 weeks in 9/25 mice. These mice were randomly assigned to either T (n=4) or E (n=5) for 4 weeks. Tumor volume (expressed as a% of its size prior to randomization) was significantly different comparing E (73.3%; range: 69.3 to 80.75%) versus T (148.39%; range: 114.07 to 165.99%) (Wilcoxon rank sum test p=0.016). Compared to control, microarray studies identified 1518 unique probe sets regulated by E (p<0.001) compared to 441 for T including estrogen-regulated genes such as progesterone receptor (PGR) and amphiregulin (AREG) that were significantly down-regulated in the E group [PGR (−6.2 fold, p=0.000008) and AREG (−3.2 fold, p=.0006) but unchanged or up-regulated in the T group (PGR unchanged and AREG +9.2 fold p=0.00002). These findings were confirmed by RT-PCR.

Conclusions: Using the MCF7/AC1 model previously used to show the superiority of AI's over T, HDE demonstrated similar antitumor activity to L and was superior to T. In cells resistant to L, E was superior to T and gene expression changes demonstrate that E down-regulates while T activates estrogen regulated genes. These findings support the ongoing development of E for the treatment of ER+ BC.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD01-06.

ACOSOG Z1031: A randomized phase II trial comparing exemestane, letrozole, and anastrozole in postmenopausal women with clinical stage II/III estrogen receptor-positive breast cancer

LBA513

Background: Neoadjuvant aromatase inhibitor (AI) therapy is a rational and effective approach to improving the breast conservation surgery (BCS) rate for postmenopausal patients with large, estrogen receptor (ER) rich breast cancers. Barriers to adopting this strategy include lack of experience in this management approach in the US and uncertainty regarding the comparative effectiveness of the three approved aromatase inhibitors for this indication.

Methods: ACOSOG Z1031 is a multicenter, open-label, neoadjuvant phase III screening study that randomized postmenopausal women with clinical stage II/III ER rich (Allred score 6-8) breast cancer to 16 weeks of either exemestane (EXE) 25 mg daily, letrozole (LET) 2.5 mg daily, or anastrozole (ANA) 1 mg daily. At baseline study participants were either marginal for BCS (MBCS), candidates for mastectomy only (MO), or inoperable (IO). Planned enrolment was 125 patients per arm in order that the likelihood of the treatment with the “best” 16-week clinical response rate (based on caliper measurements) by WHO criteria (cRR) was included among the subset of treatments with “similar” cRR (90% power). Secondary endpoints included: extent of surgery, radiologic and pathologic response rates.

Results: From 4/1/2006 to 10/1/2009, 377 postmenopausal women with clinical stage II or III ER rich breast cancer were enrolled. 374 women began treatment and were included in an intent-to-treat analysis. Median age was 66 yrs (range: 43-90 yrs), Median tumor size was 4.0 cm (range: 2-13 cm). The 16-week cRR was 60.5% (95%CI: 51.3-69.1%) for EXE; 70.9% (95% CI: 62.2-78.6%) for LET, and 66.7% (95% CI: 57.6-74.9%) for ANA. Seventeen patients did not have surgery due to refusal (12 pts), progression (3 pts) or other medical conditions (2 pts). The BCS rate was 78% (163/207) in MBCS group; 42% (77/163) in MO group; and 75% in IO group (3/4). Surgeons made the decisions regarding procedure choice 75% of the time in both the MBCS and the MO categories.

Conclusions: This large multicenter screening trial selected non-steroidal AIs for further development due to their higher observed cRR. The study demonstrates that high response and breast conservation rates and low rates of disease progression can be achieved through patient selection based on high ER expression. We are currently refining our approach for early detection of poor response to AIs through an assessment of the tumor Ki67 proliferation index at 2 to 4 weeks (Z1031 Cohort B).

[Table: see text]

Examination of Immune Competence in Breast Cancer Patients at Six Months Post Surgery and Adjuvant Therapy through Assessment of T Cell and Dendritic Cell Functionality

It has long been known that immune suppression is induced by the presence of a tumor, resulting in compromised T cell and dendritic cell (DC) functionality. What is not well understood is how soon the immune system recovers normal functionality following surgical removal of tumors and adjuvant therapy. This timing is of critical importance, as the effectiveness of therapeutic immune strategies relies on optimal presentation of antigens and activation of T cells. Blood from breast cancer patients was collected prior to surgery and at 3 and 6 months post adjuvant therapy. Patients were treated with surgery (breast conservation or mastectomy) and chemotherapy (CT) (n=22) or surgery without chemotherapy (n=38). Most patients had radiation therapy (RT). Blood from 22 healthy woman of similar age served as controls. T cell functionality (TCF) was determined following stimulation with plate-bound anti-CD3 (1 µg/ml) and anti-CD28 (0.5 µg/ml) and proliferation was measured by 3H-thymidine uptake. DC functionality (DCF) was determined by ability to present allo-antigens in a mixed lymphocyte reaction. Values for the normal samples determined the normal ranges (NR). Responses were grouped into 4 categories based on their status at 6 months: Group 1 - remained in NR; Group 2 - climbed into NR; Group 3 - remained below NR; Group 4 - fell below NR. Analysis of immunosuppression will be based on lymphocyte subsets, cytokine, COX-2, and PGE2 metabolite levels.T Cell Proliferation AllWith CTNo CT N=60N=22N=38Group 120%14%24%Group 223%23%24%Group 338%41%37%Group 418%23%16% DC Function AllWith CTNo CT N=58N=20N=38Group 143%35%47%Group 219%25%16%Group 317%15%18%Group 421%25%18% Forty-three percent of patients had normal levels (Groups 1 and 2) for TCF and 62% for DCF by 6 months post adjuvant therapy, suggesting that breast cancer patients are potentially amenable to vaccine therapy. 28% of patients had both TCF and DCF in NR; 50% had either TCF or DCF in NR; and 22% had neither in NR. The percentage of patients who had TCF in NR by adjuvant therapy was: 35% CT+RT (6/17); 33% CT (1/3); 52% (17/33) RT; and 20% (1/5) neither. The percentage of patients who had DCF in NR by adjuvant therapy was: 67% (10/15) CT+RT; 33% (1/3) CT; 67% (22/33) RT; and 40% (2/5) neither. Proper understanding of the effects of tumor, chemotherapy and radiation therapy on immune function, especially the effects on T cells and DCs, may enable us to identify the appropriate patients in whom to study immunotherapy approaches in women with early breast cancer and to examine strategies to counteract cancer-related defects in immune function. (supported by P50CA116201)

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4131.

Tamoxifen, HER2, and Endoxifen: The Role of CYP2D6 as a Predictor of Tamoxifen Resistance in ER+/HER2+ Breast Cancer

Background: Endoxifen, the active metabolite of tamoxifen (Tam), is currently being developed as a drug for the treatment of estrogen receptor (ER) + breast cancer (BC). HER2 expression in ER+ BC is associated with Tam resistance, and in vivo Tam administration to mice bearing ER+/HER2+ xenografts stimulates BC growth (Shou, JNCI 2004). In humans, endoxifen is the most important Tam metabolite responsible for inhibiting estrogen induced BC growth (Wu, Cancer Research 2009). CYP2D6 metabolism affects the concentrations (conc) of endoxifen (Stearns, JNCI, 2003) and associated with worse disease free survival (DFS) in Tam treated BC (Goetz, JCO, 2005). We sought to determine the activity of Tam and its metabolites in ER+/HER2+ BC cell lines and to evaluate the role of CYP2D6 metabolism in Tam-treated patients (pts) with ER+/HER2+ BC. Additionally, we sought to determine endoxifen conc in mice administered oral Tam.Methods: MCF7 (parental and HER2-expressing) and BT474 (ER+/HER2+) cells were used to compare the activity of Tam, 4HT, and endoxifen on estrogen- stimulated growth. Oral tam PK were characterized in mice treated with standard dose of Tam (4 mg/kg; 100 μg). Clinical data were obtained via a retrospective analysis of Tam-treated pts with ER+/ HER2+ BC randomized to receive 5 years of Tam (NCCTG 89-30-52). CYP2D6 metabolism (extensive or decreased) was based on CYP2D6 genotype (*3, 4, 6, 10, 17, 41) and co-administration of a CYP2D6 inhibitor (yes/no). HER2 was determined by immunohistochemistry (IHC) or FISH (tumors 0, 1, or 2+ by IHC). The association between CYP2D6 and DFS was assessed using the log-rank test and proportional hazards modeling.Results: Compared to Tam, endoxifen potently inhibited the growth of estrogen- stimulated BT474 cells. In MCF7 cells, expression of HER2 shifted the conc of endoxifen required for 50% inhibition of growth (IC50) from 54 nM (parental) to 131 nM (HER2 expressing). Using the range of conc of Tam and its metabolites observed in humans (Tam, 300-500 nM; 4HT, 5-10 nM; and endoxifen, 10-200 nM), only endoxifen potently inhibited estrogen- stimulated growth of MCF7HER2+ cells and only at conc achievable in CYP2D6 extensive metabolizers (>50nM). In mice, conc of 4HT and endoxifen were below 15 nM following an oral dose of 4 mg/kg. In NCCTG 89-30-52, both CYP2D6 phenotype and HER2 status was determined in 201/256 randomized pts. HER2 was expressed in 23/215 (11%) but not associated with DFS overall (p=0.62). In the HER2+ subset, pts with decreased CYP2D6 metabolism (n=10) had significantly shorter DFS compared to extensive metabolizers (n=9) (HR 9.5, p=0.03; 95% CI 1.16-76.9).Conclusions: Our in vitro and clinical data provide a simple pharmacological model for understanding HER2 resistance in Tam-treated breast cancer. Mice, which lack the CYP2D6 enzyme, may not be an appropriate model for understanding tam resistance given low conc of both 4HT and endoxifen. Given that the in vitro conc of endoxifen needed to inhibit the growth of ER+/HER-2+ BC are achievable in only a subset of humans (CYP2D6 extensive metabolizers), the primary administration of endoxifen could overcome de novo Tam resistance in ER+/HER2+ BC.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2006.

Tumor Ki67 Proliferation Index within 4 Weeks of Initiating Neoadjuvant Endocrine Therapy for Early Identification of Non-Responders

Background: The Preoperative Endocrine Prognostic Index (PEPI) scores the independent prognostic effects of tumor pathologic staging and expression levels of ER and the “proliferation” marker Ki67 in the surgical sample to predict long term outcomes after completion of neoadjuvant endocrine treatment (Ellis et al JNCI 100:1380, 2008). A limitation of the PEPI is that the prognostic information becomes available only after 4 months of treatment. We therefore evaluated the value of an early assessment of the Ki67 level in a tumor biopsy sample taken two to four weeks after initiating treatment in two neoadjuvant endocrine therapy trials for the purposes of the early identification of non- respondersMethods: A Ki67 cut point of greater than 10% for poor outcome in ER+ breast cancer was derived by comparing the PAM50 intrinsic subtype profile using a qRT-PCR assay with Ki67 data in a 700+ sample data set. A baseline level of 10% or less correlated most closely with a PAM50-based definition of LumA breast cancer and above 10% LumB breast cancer. We subsequently applied the 10% cut point to the baseline and early on-treatment Ki67 data in two trials, POL (Olson et al JACS 208:906, 2009) and IMPACT (Smith et al JCO: 23, 5108, 2005).Results: At baseline the dichotomized Ki67 definition was not significantly predictive for surgical Ki67 level, PEPI score or RFS in this modest size sample set. In contrast, in a result that emphasizes the enhaced prognostic properties of the on-treatment Ki67 approach, the one month POL sample Ki67 values (62 patients) predicted a higher level of Ki67 in the surgical samples at four months after treatment initiation (P=.01), a poorer PEPI score (P=0.01), a smaller number of patients in the PEPI risk point zero group (P=0.08) and worse relapse free survival (P=0.003). The IMPACT data (153 patients) confirmed that a two week Ki67 >10% predicted higher Ki67 in the surgical specimen (P=0.001), a poorer PEPI score (P=0.001), smaller numbers of patients in the PEPI 0 risk point group (P= 0.004) and worse relapse free survival (P=0.008).Ki67 and OutcomePOL 4W Ki67% PEPI 0RFS (events)10%>1/19 (5%)5/21 (23%)10%≤10/36 (28%)1/41 (2.4%)P ValueP=0.08 (Fisher)P=0.003 (log rank)IMPACT 2W Ki67% PEPI 0RFS (events)10%>0/32 (0%)9/35 (26%)10%≤21/101 (21%)13/118 (11%)P ValueP=0.004 (Fisher)P=0.008 (log rank) Conclusions: A tumor Ki67 assessment taken a short time (2 to 4 week window) after the initiation of neoadjuvant AI identifies patients with poor outcome ER+ disease. Amendment 6 of the neoadjuvant endocrine therapy protocol ACOSOG Z1031 will triage patients with an “on treatment” Ki67 value above 10% to chemotherapy in order to assess the pathological response rate to cytotoxic therapy in this important tumor subset.Supported by R01 CA095614, Avon PFP award 3P50 CA68438-07S2, U01 CA114722, ACOSOG U10 CA 76001, Breakthrough Cancer UK and AstraZenica (IMPACT trial).

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 78.

Progression-free and overall survival analysis in patients with metastatic melanoma undergoing first- versus second-line therapy

9078

Background: A frequently discussed topic at meetings of oncologists is the question of expected clinical outcomes for patients with metastatic melanoma undergoing 1st vs 2nd line systemic therapy. Differing outcomes in these two patient populations could affect interpretation of non-randomized clinical trials involving both patient populations. Some have suggested superior clinical outcome in patients undergoing 2nd line therapy. As there is little data addressing this issue, we sought to answer the question by comparing the clinical outcomes of patients with metastatic melanoma treated on 1st vs 2nd line therapy across clinical trials conducted at our institution. Methods: Data were collected from 10 phase II clinical trials for patients with stage IV melanoma for which Mayo Clinic was the data center. The 10 trials included three categories of treatments: cytotoxic chemotherapy (4), cancer vaccines (4), and biologic agents (2). In all studies, eligibility criteria required: stage IV melanoma, life expectancy >3 months, reasonable hematology and serum chemistry laboratory results, and an ECOG performance status of ≤2. Cox proportional hazards models were fit to assess the relationship between patients' “therapy” status (1st vs 2nd line) and time to events, both overall survival (OS) and progression free survival (PFS), for each treatment category. Results: We identified 318 unique eligible patients across 10 trials. Removed from the analysis were 55 patients (ocular melanoma and/or metastases involving the central nervous system) leaving 263. Cox proportional hazards results demonstrated no differences in PFS or OS for 1st vs 2nd line patients for either “chemotherapy” or “vaccine” treatment regimens. However, patient treated on “biologic” trials as 1st line therapy appeared to demonstrate a PFS advantage over 2nd line treatments (HR=1.98, p-value=0.02). There was a suggestion of an OS benefit for 1st line patients in this category, however, the relationship was not significant (HR=1.77, p=0.07). Conclusions: The presented data suggest that there is no PFS/OS difference in stage IV melanoma patients receiving 1st vs 2nd line therapy (no PFS/OS advantage to patients treated in 2nd line vs. 1st line).

No significant financial relationships to disclose.

Phase II trial of carboplatin, weekly paclitaxel, and biweekly bevacizumab in patients with unresectable stage IV melanoma

8560

Background: In patients with metastatic melanoma, the combination of chemotherapy with an agent that specifically targets vascular endothelial growth factor (VEGF) might be able to control tumor growth and progression much more effectively than chemotherapy alone. Methods: A two-stage phase II clinical trial was conducted in patients with unresectable stage IV melanoma to assess the anti-tumor activity and toxicity profile of the combination of paclitaxel (80 mg/m2 IV on days 1, 8 and 15 of a 28-day cycle), carboplatin (AUC = 6 IV on day 1) and bevacizumab (10 mg/kg IV on days 1 and 15). The primary end point of the study was the 8-week progression-free survival rate (PFS). Enrollment to the second stage of the study was opened if 8 or more of the first 20 patients enrolled remained progression-free at 8 weeks. Eligible patients had measurable disease by RECIST criteria, a performance status (PS) of 0–2 and acceptable pre-registration organ function. Exclusion criteria included: brain metastases, significant recent bleeding, uncontrolled hypertension and ongoing anticoagulation. The study opened in February 2006 and completed full study accrual in August 2006. Data from the 20 patients enrolled in the first stage are presented here. Results: Patients (60% male) had a median age of 63 and had a good performance status (85% had PS of 0). M1c disease was present in 45% of patients and 35% had undergone previous chemotherapy for stage IV melanoma (50% prior immunotherapy). Only 6 patients did not complete more than 2 cycles of chemotherapy due to refusal (3), desire for alternative treatment (1) or progression (2). Median follow-up among the 15 patients still alive was 5.5 months (range: 6 weeks - 9 months). The 8-week PFS rate was 70% (14/20). The median time to progression was 163 days. One partial response was observed. There were 3 disease-related deaths at 65, 120 and 190 days post-registration. The most common toxicities were neutropenia (95%; 45% = grade 3), anemia (95%; 15% = grade 3), fatigue (90%; 5% = grade 3), leukopenia (85%; 25% = grade 3), and thrombocytopenia (75%; 5% = grade 3). Conclusions: The combination of paclitaxel, carboplatin and bevacizumab appears to be well tolerated and clinically active in patients with stage IV melanoma.

No significant financial relationships to disclose.

A phase II study of ABT-510 for the treatment of metastatic melanoma

8041

Background: ABT-510 is a synthetic peptide analog of thrombospondin-1 demonstrating inhibition of VEGF/bFGF mediated human endothelial cell migration, proliferation, tube formation, cornea-neovascularization as well as inhibition of tumor growth in vivo (B16F10 melanoma). Having been found to be safe in phase I testing, ABT-510 has entered phase II trials. Presented are the results of a phase II study using ABT-510 for the treatment of stage IV melanoma. Methods: A two stage phase II clinical trial was conducted to assess the anti-tumor activity, safety profile and pharmacodynamics of ABT510 in patients with stage IV melanoma. Patients self-administered 100mg of ABT-510 subcutaneously twice/day. Therapy was continued in the absence of excessive toxicity or tumor progression. Primary endpoint was 18 week progression free survival rate. Enrolled were patients at least 18 years of age with measurable (RECIST) metastatic melanoma, ECOG performance status of 0–2 and normal pre-registration blood tests. Exclusion criteria included: cancer therapy less than 4 weeks prior to registration; failure to recover from prior therapy; brain metastases; significant recent bleeding; uncontrolled hypertension; and ongoing anti-coagulation. Pregnant or nursing women were not eligible. Results: Twenty-one patients (67% male) were enrolled with a median age of 55 years. Most patients had M1c disease (80%) and 62% had prior chemotherapy for stage IV melanoma. None of the patients were ineligible/canceled participation. After the first stage of the trial was complete, only 3 of the first 20 patients enrolled were progression-free at 18 weeks. Having not met the minimal clinical efficacy requirement (at least 7 of the first 20 patients progression-free at 18 weeks) the trial was closed to further accrual. Correlative laboratory studies suggested decreases in some of the measured parameters of angiogenesis (VEGFC, circulating endothelial cells) with no impact on immune homeostasis. Conclusions: Single agent ABT-510 therapy administered at 100mg twice/day to patients with previously treated metastatic melanoma did not demonstrate significant clinical efficacy. However, changes in measured parameters of angiogenesis suggest possible clinical efficacy with higher dosing or in combination with cytotoxic therapy.

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Blood transfusion and risk of non-Hodgkin's lymphoma

A few epidemiologic studies have suggested that blood transfusion may be a risk factor for non-Hodgkin's lymphoma. The authors tested this hypothesis in a population-based, case-control study, using pathologically verified non-Hodgkin's lymphoma cases and transfusion documented via medical records. In 221 age- and sex-matched case-control pairs from Olmsted County, Minnesota, in 1975-1993, the authors observed an odds ratio of 0.84 (95% confidence interval 0.50-1.41) for history of transfusion and non-Hodgkin's lymphoma. There also was no apparent association between transfusion and non-Hodgkin's lymphoma in any subgroup analysis. Results do not support the hypothesis that blood transfusion contributes to the occurrence of non-Hodgkin's lymphoma.

Brain metastases from colorectal carcinoma. The long term survivors

BACKGROUND

Brain metastases occur in 25% to 35% of all cancer patients, with colorectal carcinoma accounting for approximately 8% of these. Information about patients with brain metastases from colorectal carcinoma is limited, with the largest previous series reporting only 40 patients. To date there have been no reports describing the subgroup of patients with long term survival ( > 1 yr).

METHODS

A retrospective review of 150 patients seen at the Mayo Clinic between 1976 and 1993 with pathologic (56) and/or radiographic (94) confirmation of brain metastases from colorectal carcinoma is presented.

RESULTS

The majority of patients (82%) with brain metastases from colorectal carcinoma have concomitant extracerebral metastases, especially in the lungs. Only 16% of the patients survived > 1 year after diagnosis (4 > 4 yrs., 2 > 10 yrs). Of these, 92% had single cerebral metastases and 38% had no systemic metastases. In addition, young age and the absence of bony metastases or memory loss were associated with increased survival. Median survival for all of the patients receiving surgery and radiotherapy (39), surgery alone (11), radiotherapy alone (79) and supportive care (17) are 42, 45, 16, and 8 weeks, respectively. Thirty percent of the patients treated with radiotherapy showed regression of their tumors on follow-up head scans; three had complete regression.

CONCLUSIONS

One-year survivors of brain metastases from colorectal carcinoma were uncommon, accounting for 16% of the patients and most of these (92%) had solitary lesions. Nineteen of 24 long term survivors had surgical resection as part of their treatment. Given the similar results in patients treated with surgery plus radiotherapy and those treated with surgery alone, as well as the potential long term side effects of radiotherapy, withholding radiotherapy for those patients with the possibility of long term survival should be considered.

Brain metastases from colorectal carcinoma. The long term survivors

BACKGROUND

Brain metastases occur in 25% to 35% of all cancer patients, with colorectal carcinoma accounting for approximately 8% of these. Information about patients with brain metastases from colorectal carcinoma is limited, with the largest previous series reporting only 40 patients. To date there have been no reports describing the subgroup of patients with long term survival ( > 1 yr).

METHODS

A retrospective review of 150 patients seen at the Mayo Clinic between 1976 and 1993 with pathologic (56) and/or radiographic (94) confirmation of brain metastases from colorectal carcinoma is presented.

RESULTS

The majority of patients (82%) with brain metastases from colorectal carcinoma have concomitant extracerebral metastases, especially in the lungs. Only 16% of the patients survived > 1 year after diagnosis (4 > 4 yrs., 2 > 10 yrs). Of these, 92% had single cerebral metastases and 38% had no systemic metastases. In addition, young age and the absence of bony metastases or memory loss were associated with increased survival. Median survival for all of the patients receiving surgery and radiotherapy (39), surgery alone (11), radiotherapy alone (79) and supportive care (17) are 42, 45, 16, and 8 weeks, respectively. Thirty percent of the patients treated with radiotherapy showed regression of their tumors on follow-up head scans; three had complete regression.

CONCLUSIONS

One-year survivors of brain metastases from colorectal carcinoma were uncommon, accounting for 16% of the patients and most of these (92%) had solitary lesions. Nineteen of 24 long term survivors had surgical resection as part of their treatment. Given the similar results in patients treated with surgery plus radiotherapy and those treated with surgery alone, as well as the potential long term side effects of radiotherapy, withholding radiotherapy for those patients with the possibility of long term survival should be considered.

Randomized Trial of the Canalith Repositioning Procedure

Thirty-six subjects with confirmed, unilateral benign paroxysmal positioning vertigo of at least 2 months' duration were randomly assigned to one of two treatment groups. After complete informational counseling and explanation of the posttreatment instructions, subjects were randomly assigned to receive either Epley's canalith repositioning procedure or a placebo maneuver. All subjects completed a daily diary for 1 month to document any dizzy spells and their adherence to the posttreatment instructions. Follow-up Dix-Hallpike testing was performed after 1 month by an audiologist who was blinded to the patient's treatment group status. Analysis of Dix-Hallpike results confirmed that those who received the canalith repositioning procedure had significantly more negative responses (88.9%) than did those in the placebo group (26.7%).

Randomized trial of the canalith repositioning procedure

Thirty-six subjects with confirmed, unilateral benign paroxysmal positioning vertigo of at least 2 months' duration were randomly assigned to one of two treatment groups. After complete informational counseling and explanation of the posttreatment instructions, subjects were randomly assigned to receive either Epley's canalith repositioning procedure or a placebo maneuver. All subjects completed a daily diary for 1 month to document any dizzy spells and their adherence to the posttreatment instructions. Follow-up Dix-Hallpike testing was performed after 1 month by an audiologist who was blinded to the patient's treatment group status. Analysis of Dix-Hallpike results confirmed that those who received the canalith repositioning procedure had significantly more negative responses (88.9%) than did those in the placebo group (26.7%).

Prostate-specific antigen detected prostate cancer: pathological characteristics of ultrasound visible versus ultrasound invisible tumors

Most studies examining the issue of 'early detection of prostate cancer' advocate the combined use of serum prostate-specific antigen (PSA) and digital rectal examination (DRE). As a result, a significant number of new prostate cancers are diagnosed on the basis of an elevated serum PSA when the DRE is unremarkable. The purpose of this study is to determine if the PSA-detected tumors that are visible on transrectal ultrasound (TRUS) have the same pathological characteristics as PSA-detected tumors that are invisible on TRUS. One hundred and ninety-four patients with an elevated serum PSA concentration and nonpalpable prostate cancer who underwent radical retropubic prostatectomy (RRP) at our institution between March 1988 and December 1991 were reviewed. The patients were divided into two groups: 97 (50%) had no identifiable lesion on TRUS, and 97 (50%) had at least one hypoechoic area consistent with adenocarcinoma of the prostate. The pathological characteristics of the RRP specimens from the two groups were compared. There was no significant difference in the age (p = 0.14) or the preoperative serum PSA values (p = 0.18) between the groups. Also, there was no significant difference between the groups with regard to tumor volume (p = 0.89), focality of the cancer (p = 0.43), Gleason score (p = 0.81), DNA ploidy status (p = 0.96), pathological stage (p = 0.92), surgical margin involvement (p = 0.27), and tumor location (p = 0.64). These findings suggest that the clinical TNM staging system for prostate cancer may be simplified by eliminating the distinction between PSA-detected cancers visible on TRUS and PSA detected cancers not visible on TRUS.(ABSTRACT TRUNCATED AT 250 WORDS)