Retrospective study to estimate the prevalence and describe the clinicopathological characteristics, treatments received, and outcomes of HER2-low breast cancer

BACKGROUND

Approximately 80% of all breast cancers (BCs) are currently categorized as human epidermal growth factor receptor 2 (HER2)-negative [immunohistochemistry (IHC) 0, 1+, or 2+/in situ hybridization (ISH) negative]; approximately 60% of BCs traditionally categorized as HER2-negative express low levels of HER2. HER2-low (IHC 1+ or IHC 2+/ISH-) status became clinically actionable with approval of trastuzumab deruxtecan to treat unresectable/metastatic HER2-low BC. Greater understanding of patients with HER2-low disease is urgently needed.

PATIENTS AND METHODS

This global, multicenter, retrospective study (NCT04807595) included tissue samples from patients with confirmed HER2-negative unresectable/metastatic BC [any hormone receptor (HR) status] diagnosed from 2014 to 2017. Pathologists rescored HER2 IHC-stained slides as HER2-low (IHC 1+ or IHC 2+/ISH-) or HER2 IHC 0 after training on low-end expression scoring using Ventana 4B5 and other assays at local laboratories (13 sites; 10 countries) blinded to historical scores. HER2-low prevalence and concordance between historical scores and rescores were assessed. Demographics, clinicopathological characteristics, treatments, and outcomes were examined.

RESULTS

In rescored samples from 789 patients with HER2-negative unresectable/metastatic BC, the overall HER2-low prevalence was 67.2% (HR positive, 71.1%; HR negative, 52.8%). Concordance was moderate between historical and rescored HER2 statuses (81.3%; κ = 0.583); positive agreement was numerically higher for HER2-low (87.5%) than HER2 IHC 0 (69.9%). More than 30% of historical IHC 0 cases were rescored as HER2-low overall (all assays) and using Ventana 4B5. There were no notable differences between HER2-low and HER2 IHC 0 in patient characteristics, treatments received, or clinical outcomes.

CONCLUSIONS

Approximately two-thirds of patients with historically HER2-negative unresectable/metastatic BC may benefit from HER2-low-directed treatments. Our data suggest that HER2 reassessment in patients with historical IHC 0 scores may be considered to help optimize selection of patients for treatment. Further, accurate identification of patients with HER2-low BC may be achieved with standardized pathologist training.

Recurrent hyperactive ESR1 fusion proteins in endocrine therapy-resistant breast cancer

Background

Estrogen receptor-positive (ER-positive) metastatic breast cancer is often intractable due to endocrine therapy resistance. Although ESR1 promoter switching events have been associated with endocrine-therapy resistance, recurrent ESR1 fusion proteins have yet to be identified in advanced breast cancer.

Patients and methods

To identify genomic structural rearrangements (REs) including gene fusions in acquired resistance, we undertook a multimodal sequencing effort in three breast cancer patient cohorts: (i) mate-pair and/or RNAseq in 6 patient-matched primary-metastatic tumors and 51 metastases, (ii) high coverage (>500×) comprehensive genomic profiling of 287-395 cancer-related genes across 9542 solid tumors (5216 from metastatic disease), and (iii) ultra-high coverage (>5000×) genomic profiling of 62 cancer-related genes in 254 ctDNA samples. In addition to traditional gene fusion detection methods (i.e. discordant reads, split reads), ESR1 REs were detected from targeted sequencing data by applying a novel algorithm (copyshift) that identifies major copy number shifts at rearrangement hotspots.

Results

We identify 88 ESR1 REs across 83 unique patients with direct confirmation of 9 ESR1 fusion proteins (including 2 via immunoblot). ESR1 REs are highly enriched in ER-positive, metastatic disease and co-occur with known ESR1 missense alterations, suggestive of polyclonal resistance. Importantly, all fusions result from a breakpoint in or near ESR1 intron 6 and therefore lack an intact ligand binding domain (LBD). In vitro characterization of three fusions reveals ligand-independence and hyperactivity dependent upon the 3' partner gene. Our lower-bound estimate of ESR1 fusions is at least 1% of metastatic solid breast cancers, the prevalence in ctDNA is at least 10× enriched. We postulate this enrichment may represent secondary resistance to more aggressive endocrine therapies applied to patients with ESR1 LBD missense alterations.

Conclusions

Collectively, these data indicate that N-terminal ESR1 fusions involving exons 6-7 are a recurrent driver of endocrine therapy resistance and are impervious to ER-targeted therapies.

Abstract OT1-13-01: MammaPrint, BluePrint, and full-genome data linked with clinical data to evaluate new gene expression profiles (FLEX)

BACKGROUND: Genomic signatures are revolutionizing the definition, identification, and treatment of breast cancer subtypes. The ability of genomic signatures to enable fine grained stratification of breast cancers to the granular disease level is still generally untested because of the difficulties in aggregating large clinical data sets. In order to stratify breast cancers into actionable subtypes both the full genome data and clinical data must be collected for patients at scale.

DESIGN & METHODS: FLEX is designed as a novel, large-scale, population based, prospective registry. All patients with stage I-III breast cancer who receive MammaPrint (MP) or BluePrint (BP) testing on a primary breast tumor are eligible. FLEX utilizes an adaptive design which enables additional study arms at low incremental effort and cost by allowing targeted substudies to be added. Patients who are enrolled in the initial study will also be eligible for inclusion in any additional study arm where they meet all criteria. Additional study arms and substudies may be investigator-initiated.

SPECIFIC AIMS:

Primary: Create a big-data registry of full genome expression data and clinical data to investigate new gene associations with prognostic and/or predictive value.

Secondary: Generate hypotheses for targeted subset analyses and trials based on full genome data. To date the following substudies have been proposed:

DR. JENNIFER A. CROZIER, BAPTIST MD ANDERSON CANCER CENTER

(1) MP and BP in male breast cancer TYPE: SUBSTUDY; NO ADDITIONAL CONSENT (ICF) REQUIRED. ARMS: ALL (2) MP BP evaluation in breast cancer patients ≥70. TYPE: SUBSTUDY; NO ADDITIONAL ICF REQUIRED. ARMS: ALL (3) FG evaluation in ILC. TYPE: SUBSTUDY; NO ADDITIONAL ICF REQUIRED. ARMS: ALL (4,5) MP BP relation to PR positivity, Ki67. TYPE: SUBSTUDY; NO ADDITIONAL ICF REQUIRED. ARMS: ALL (6) MP BP in metaplastic breast cancer. TYPE: SUBSTUDY; NO ADDITIONAL ICF REQUIRED. ARMS: ALL

DR. ADAM M. BRUFSKY, UNIVERSITY OF PITTSBURGH MEDICAL CENTER MAGEE WOMENS HOSPITAL

(1) Response to standard chemotherapy regimens in clinically ER+/PR+/HER2+ (triple positive) patients according to BP molecular subtypes. (2) Expression signatures by response to bisphosphonates in ER+ patients receiving adjuvant therapy, or for osteoporosis after primary treatment. (3) Gene expression in breast cancer patients with obesity. TYPE: SUBSTUDY; DUAL ICF UTILIZED. ARMS: NEOADJUVANT AND ADJUVANT

DR. IAN GRADY, NORTH VALLEY BREAST CLINIC

Impact of genomic risk classification on travel time to receive breast cancer care. TYPE: SUBSTUDY; NO ADDITIONAL ICF REQUIRED. ARMS: ALL

DR. THOMAS LOMIS, VALLEY BREAST CARE

Complementary data collection for patients participating in the ODM-201 trial. FLEX provides gene expression for exploratory and signature discovery. TYPE: COMPLEMENTARY; DUAL ICF UTILIZED. ARM: NEOADJUVANT

DR. PAT WHITWORTH, NASHVILLE BREAST CENTER

Genomic reclassification of large tumors eligible to receive NCT therapy. TYPE: SUBSTUDY; NO ADDITIONAL ICF REQUIRED. ARM: NEOADJUVANT

ELIGIBILITY, ACCRUAL

FLEX will enroll a minimum of 10000 patients aged ≥18 with stage I-III breast cancer who sign ICF. Enrollment began April 2017 and 623 patients have been enrolled as of June 2018.

Citation Format: Brufsky AM, Crozier JA, Grady I, Lomis T, Whitworth P, Rehmus E, Srkalovic G, Lee L, Blumencranz P, Baron P, Mavromatis B, Untch S, Blumencranz L, Yoder EB, Audeh W, FLEX Investigators Group. MammaPrint, BluePrint, and full-genome data linked with clinical data to evaluate new gene expression profiles (FLEX) [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 OT1-13-01.

Abstract GS4-07: Race, ethnicity and clinical outcomes in hormone receptor-positive, HER2-negative, node-negative breast cancer: results from the TAILORx trial

Background: Black race is associated with worse outcomes in localized hormone receptor (HR)-positive breast cancer in population-based and in clinical trial cohorts, whether using self-identified race (Albain et al. JNCI 2009 [PMID: 19584328; Sparano et al. JNCI 2012 [PMID: 22250182) or genetically-identified race (Schneider et al. J Precision Oncol 2017 [PMID: 29333527]). This disparity persists after adjustment for treatment delivery parameters (Hershman et al. JCO 2009 [PMID:19307504]). We evaluated clinicopathologic characteristics, treatment delivered and clinical outcomes in the Trial Assigning Individualized Options for Treatment (TAILORx) by race and ethnicity (Sparano et al. NEJM 2018 [PMID: 29860917]).

Methods: The analysis included 9719 evaluable TAILORx participants. The association between clinical outcomes and race (white, black, Asian, other/unknown) and ethnicity (Hispanic vs. non-Hispanic) was examined, including invasive disease-free survival (iDFS), distant relapse-free interval (DRFI), relapse-free interval (RFI), and overall survival (OS). Proportional hazards models were fit including age (5 categories), tumor size (>2 cm vs. <=2 cm), histologic grade (high vs. medium vs. low vs. unknown), continuous recurrence score (RS), race, and ethnicity in the overall population and randomized treatment arms in the RS 11-25 cohort.

Results: The study population included 8189 (84%) whites, 693 (7%) blacks, 405 (4%) Asians, and 432 (4%) with other/unknown race. Regarding ethnicity, 7635 (79%) were non-Hispanic, 889 (9%) Hispanic, and 1195 (12%) unknown. There was no significant difference in RS distribution (p=0.22) in blacks compared with whites, or in median (17 vs. 17) or mean RS (19.1 vs. 18.2). There was likewise no difference in Hispanic vs. non-Hispanic ethnicity for RS distribution (p=0.72) or median (17 vs. 17) or mean RS (18.5 vs. 18.0). Black race (39% vs. 30%) and Hispanic ethnicity (39% vs. 30%) were both associated with younger age (</=50 years) at diagnosis. The use and type of adjuvant chemotherapy and endocrine therapy, and duration of endocrine therapy, were similar in black (vs. white) and Hispanic (vs. non-Hispanic) populations. In proportional hazards models, black race (compared with white race) was associated with worse clinical outcomes in the entire population and in those with a RS 11-25 (see table). Hispanic ethnicity was generally associated with better outcomes (compared with non-Hispanic ethnicity). For the cohort with a RS of 11-25, there was no evidence for chemotherapy benefit for any racial or ethnic group.

Race (black vs.white) and clinical outcomes in proportional hazards modelsClinical endpointEntire Population (N=693 black) Hazard ratio for eventRS 11-25 (N=471 black) Hazard ratio for eveniDFS1.33 (p=0.005)1.49 (p=0.001)DRFI1.21 (p=0.28)1.60 (p=0.02)RFI1.39 (p=0.02)1.80 (p<0.001)OS1.52 (p=0.005)1.67 (p=0.003

Conclusions: In patients eligible and selected for participation in TAILORx, black women had worse clinical outcomes despite similar 21-gene assay RS results and comparable systemic therapy. This adds to an emerging body of evidence suggesting a biologic basis or other factors contributing to racial disparities in HR-positive breast cancer that requires further evaluation.

Citation Format: Albain K, Gray RJ, Sparano JA, Makower DF, Pritchard KI, Hayes DF, Geyer, Jr. CE, Dees EC, Goetz MP, Olson, Jr. JA, Lively T, Badve SS, Saphner TJ, Wagner LI, Whelan TJ, Ellis MJ, Paik S, Wood WC, Ravdin PM, Keane MM, Gomez HL, Reddy PS, Goggins TF, Mayer IA, Brufsky AM, Toppmeyer DL, Kaklamani VG, Berenberg JL, Abrams J, Sledge, Jr. GW. Race, ethnicity and clinical outcomes in hormone receptor-positive, HER2-negative, node-negative breast cancer: results from the TAILORx trial [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 GS4-07.

Abstract GS2-03: Highly recurrent transcriptional remodeling events in advanced endocrine resistant ER-positive breast cancers

BACKGROUND: Although individual cancers are driven by heterogeneous processes, cancer mortality has a near universal cause—therapy resistance, recurrence and metastasis to vital organs. Characterizing more advanced tumors has borne valuable insight into cancer progression, yet studies of longitudinally collected breast cancer specimens are scarce given lengthy periods of cancer dormancy. In this study, we aimed to create the most comprehensive characterization of gene expression alterations to date between patient-matched pairs of primary and advanced ER-positive breast cancers.

MATERIALS/METHODS: Hybrid-capture RNA-sequencing was performed on 50 patient-matched pairs of primary and advanced ER-positive tumors from various recurrence sites (9 brain, 11 bone, 3 GI, 10 ovary, 17 local). Time to recurrence was up to 14.1 years with a median of 3.4 years. A shared variant analysis confirmed all paired samples were patient-matched. 1,380 cancer-related genes were analyzed for outlier expression fold-changes in matched recurrences versus primary tumors. Pair-specific, outlier fold-change thresholds were defined as Q1/Q3 +/- [1.5 X IQR]; using each pairs' fold-change values across all genes as the distribution. These discrete, longitudinal transcriptional remodeling events (LTREs) were assessed for recurrence across all sites and analyzed for enrichments within specific cohorts (Fisher's exact tests), such as locoregional vs. distant recurrences. To determine if LTREs represent acquired vulnerabilities, ex vivo and in vivo experiments targeting a recurrent, druggable LTRE gain of RET was performed.

RESULTS: The majority of advanced cancers were transcriptionally similar to patient-matched primaries with 23 of 33 distant metastases retaining PAM50 assignments of the matched primary—shifts to HER2 (n=4, 12%) or Luminal B (n=5, 15%) subtypes accounted for most metastatic discordances. Despite this intrinsic conservation, remarkably recurrent gene-level LTRE gains and losses were observed in advanced disease. Recurrent LTRE gains included NCAM1 [42%], FGFR4 [40%], IBSP [36%], ROBO2 [36%] and SPP1 [30%]. Notable LTRE losses included RELN [42%] and ESR1 [26%]. NCAM1 LTREs showed the most significant enrichments (p < 0.001) in distant disease (20 of 33, 61%) versus locoregional disease (1 of 17, 6%). A prominent LTRE enriched in brain metastasis (BrM) was RET (p-value = 0.003), expression of which showed outlier gains in 56% of ER-positive BrM. Marked anti-tumor activity was demonstrated with the RET inhibitor cabozantinib in ex vivo explant cultures of patient resected BrMs (n=3) and a BrM patient-derived xenograft.

CONCLUSIONS: Taken together, these results demonstrate profound, recurrent and metastatic site-specific LTREs in advanced breast cancers, which may be essential to our understanding of endocrine-therapy resistance and metastasis. Although current emphasis for longitudinal clinical profiling of tumors is on DNA-level alterations, these results suggest LTREs as a compelling, shared mechanism of cancer progression. Given remarkably high recurrence rates of specific LTREs across multiple cohorts, further preclinical and clinical investigations of LTREs are demanded, especially considering some (i.e. FGFR4 and RET) are readily druggable.

Citation Format: Priedigkeit N, Vareslija D, Basudan A, Watters RJ, Lucas PC, Davidson NE, Blohmer J-U, Denkert C, Machleidt A, Heppner BI, Brufsky AM, Oesterreich S, Young L, Lee AV. Highly recurrent transcriptional remodeling events in advanced endocrine resistant ER-positive breast cancers [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 GS2-03.

Abstract P2-10-08: A predictive test for neoadjuvant chemotherapy in breast cancer identifies a subset of triple negative patients with resistant disease and the poorest prognosis

Prediction of pathological complete response (pCR) for neoadjuvant treatment is an area of unmet clinical need, especially for triple negative breast cancer (TNBC) as pCR is correlated with better outcomes. Predicting which patients will have residual disease (RD) provides an opportunity to improve treatment planning. We developed a test to predict which patients are likely to achieve pCR or RD to the standard of care (taxane-based) neoadjuvant chemotherapy using gene expression profiling of 325 previously identified novel biomarkers.

Three microarray datasets were used (GSE22226, GSE25055, and GSE25065) including a total of 594 stage II-III breast cancer patients of which 125 (21%) achieved pCR, and 469 (79%) RD. ER+ tumors were present in 57% of the patients and 52% were PGR+. Almost 90% of the patients were Her2-. Of 231 TNBC, 78 (33.8%) achieved pCR, while 153 (66.2%) RD. Of 303 ER+Her- patients 26 (8.6%) achieved pCR while 277 (91.4%) RD. The cohort was divided into balanced populations with 476 patients used for training (80%) and test (20%) rounds of model development, while 118 patients were reserved as a validation set. Combining a “winnowing” process to remove genes with least predictive power, and hundreds of thousands of step-wise runs, followed by ranking genes based on conditional probabilities, we developed a 17-gene cassette (BA100) which was locked-down in the validation set with ROC (AUC) = 0.818. With a cut-off of 83% sensitivity and 68% specificity (PPV 0.4; NPV 0.94), BA100 achieved a 16% true positive rate (true pCR) and 55% true negative rate (true RD) identifying 76% of the patients who achieved pCR, and 69% of the patients with RD. In TNBC, BA100 classified 29% as true positives (TP), 36% as false positive (FP), 30% true negative (TN), and 4.8% false negative (FN). Kaplan Meier (KM) curves showed a significant difference in 5-year disease-free survival (5Y DFS) between TP and TN (p=0.00453) or FP (p=2.09E-06). However, FP had even worse outcomes than TN patients. To improve the TP rate, additional genes expressed in TNBC plus the original 325 genes were subjected to a second round of gene selection to discriminate between TP and FP, resulting in a 16-gene cassette (BA100.1). With a cut-off of 95% sensitivity and 73% specificity (PPV 0.7; NPV 0.95), applying BA100.1 reduced the FP rates from 24% to 9%, while correctly identifying 88% of RD in the validation set. KM curves showed no significant difference in 5Y DFS between 124 TNBC (53.7%) classified as TN versus 29 TNBC (12.6%) classified as FP, while a significant difference in survival rate was found between TNBC classified as TN vs TP (Cox Proportional Harzard p=8.42e-05).

Taken together, we developed a predictive test consisting of two gene cassettes that accurately identified 71% (88/104) of pCR, and 88% (417/469) of RD patients. Gene cassettes include several transcriptional repressors, PI3K signal transduction, components of telomerase, DNA repair genes, fatty acid metabolism and estrogen-independent proliferation. The test stratified TNBC with differential response to chemotherapy and survival rates so that novel approaches can be used without delay. Further validation will confirm the test utility.

Citation Format: Fournier MV, Chen J, Obenauer J, Goodwin EC, Tannenbaum SH, Brufsky AM. A predictive test for neoadjuvant chemotherapy in breast cancer identifies a subset of triple negative patients with resistant disease and the poorest prognosis [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 P2-10-08.

Abstract P4-08-04: The clinical utility of oncotype Dx for patients with recurrence scores of 10 or less: A value based pathology study of tumor histopathology and outcomes analysis in an integrated delivery and finance health system

Introduction

The majority of publications regarding breast cancer GEPTs rarely supply detailed breast tumor histopathology in their outcome studies. As a result, the cost effective role of clinical risk assessment with histopathology of breast carcinomas tends to be minimized. The aims of this study are to characterize the details of breast tumor histopathology of patients with Oncotype Dx Recurrence Scores (RS) of 10 or less, and determine if Oncotype Dx offers value and clinical utility for patients with these low grade tumors

Methods

A total of 459 patients (18%) with Oncotype Dx RS of 10 or less were retrieved from a registry of 2558 patients with Oncotype Dx results. Patients had five years of follow-up with tumor registry and were treated with endocrine therapy alone. Tissue slides were available to review on 441/459 patients. Recorded details included (1) histopathologic type of carcinoma (2) mitotic score (MS), tubule formation, nuclear pleomorphism and Notttingham histologc (NG) grade. (3) Estrogen (ER) and progesterone (PgR) semiquantitated by Allred Score and Histologic Score (H Score: strong 200-300, moderate 100-199, weak <100). (4) Lymph node status. (5) overall survival and breast cancer specific survival.

Results

Patient ages were 33-92, with mean/median age of 60, and all had endocrine therapy alone. 148 of 441(34%) patients had carcinomas of “special types”, notable for low grade/good prognosis including tubular 22(15%), cribriform 15 (10.1%), papillary 17 (11.5%), and mucinous 28 (21%), along with 63 (42.5%) low grade classic lobular carcinomas and 3 (2%) low grade mixed ductal and lobular carcinomas. All 148 tumors had a MS of 1, were NG1 and had high ER HScores (280 median/263 mean) (Allred Scores 7-8) and high PR HScores (210 median/201 mean) (Allred Scores 6-8). The remaining 293 tumors were ductal carcinomas of no special type (NST), and 261/293 (89%) of these had a MS of 1/NG2. Of the remaining cases, 10 (3%) had a MS of 2/NG2, 18 (6%) had MS of 2/NG3 and four (1%) were MS3/NG3. Estrogen receptor H Score/Allred Score was strong (Allred Score 7-8) in 395/441 (89.6%), moderate in 45 (10.2%) and weak in 1 patient (0.2%). Progesterone HScores were strong in (Allred Score 6-8) 269/441 (76%) and moderate in the remainder. Strong and moderate ER comprised 99.8% of tumors. Thus, tumors with MS1, and NG1, all with ER HScore >200 (Allred Score of 7-8) were enriched in the RS <10, and these features distinguished this group from other tumors with a MS1.

At 5 years, 433 patients (98%) were alive, 8 were dead, 1 from breast cancer due to distant recurrence. The 5-year breast cancer specific survival for this group was 99.7%. [95%CI 98.5-99.9.] 87 cases were accrued in the ongoing prospective study to date. There were 15/87 (17%) cases, 95% of which were correctly identified by pathologists as having an RS <10 using the criteria defined, with sensitivity 95%, specificity 86%, PPV 63% 95% CI(49.76-75.08), NPV 99% 95% CI(90.7-99.78). No patient had a recurrence score >22.

Conclusions

Pathologists can identify these low risk tumors with high accuracy. Oncotype Dx lacks clinical value and utility in this setting.

Citation Format: Dabbs DJ, Serdy K, Onisko A, Clark BZ, Bhargava R, Smalley S, Perkins S, Brufsky AM. The clinical utility of oncotype Dx for patients with recurrence scores of 10 or less: A value based pathology study of tumor histopathology and outcomes analysis in an integrated delivery and finance health system [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 P4-08-04.

Abstract P6-07-07: ESR1 amplification and 5'-3' exon imbalance in metastatic breast cancer

BACKGROUND: Growing evidence indicates that base pair mutations in ESR1 are relatively uncommon in newly diagnosed, treatment-naive breast cancer, but frequently acquired in hormone-resistant metastatic breast cancer (MBC). We and others have recently identified ESR1 gene fusion and amplification in MBC, with the ESR1 fusions generally encompassing AF1 and the DNA binding domain. The genomic break required for gene fusions often results in an imbalance in the DNA copy number of exons around the break. We examined ESR1 amplification and 5' and 3' exon copy number imbalance in MBC.

MATERIALS and METHODS: We designed NanoString DNA hybridization probes against coding and non-coding exons (n=9) in ESR1 and 15 reference probes. We analyzed 128 samples consisting of 61 ER-positive and 44 ER-negative metastases, and 23 primary breast cancers. DNA copy number (CN) was determined using nSolver, with >2.7CN as copy number gain, and >10 as CN amplification. ESR1 CN was calculated by averaging the DNA copy number obtained from all coding exons. The 5'-3' copy number ratio was the average copy number of the 5' exons (3-6) divided by the 3' exons (7-10).

RESULTS: 8 (13%) ER positive metastatic breast cancers showed ESR1 amplification with 5 (8%) having >2.7CN, and 3 (5%) with >10CN. In contrast, in ER-negative metastases, we did not detect any samples with amplification >10CN, and a gain (>2.7 CN) in one case. Similarly, in ER+ primary cancers we did not detect any samples with >10 CN amplifications and 2 samples with CN gain (>2.7 CN). ESR1 showed 5'-3' CN imbalance in 1 primary (5%) and in 5 metastatic (5%) breast cancers. We are currently confirming and expanding these data in a larger dataset.

CONCLUSIONS: In addition to ESR1 mutations, ESR1 CN amplifications and 5'-3' imbalance are represent frequent occurrences in endocrine resistant breast cancer. Future studies are aimed at understanding whether the observed exon imbalances are associated with generation of fusion proteins, and whether and how ESR1 amplifications cause changes in endocrine treatment response.

Citation Format: Oesterreich S, Basudan A, Preideigkeit N, Hartmaier RJ, Bahreini A, Gyanchandani R, Leone JP, Lucas PC, Hamilton RL, Brufsky AM, Lee AV. ESR1 amplification and 5'-3' exon imbalance in metastatic 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 P6-07-07.

Abstract PD1-05: Breast cancer brain metastases show limited intrinsic subtype switching, yet exhibit acquired ERBB2 amplifications and activating mutations

BACKGROUND: Metastasis is the major cause of mortality in breast cancer (BrCa) patients. Our understanding of brain metastasis (BrM) is limited, reflected by a lack of effective treatments. We aimed to (1) determine BrCa gene signature differences between primary tumors and matched BrM and (2) uncover BrM-specific alterations that may be clinically actionable.

MATERIALS and METHODS: NanoString expression profiling of 127 genes from 5 major prognostic tests (MammaPrint, EndoPredict, PAM50, OncotypeDX, MGI) was performed on 20 patient-matched primary (10 ER-neg, 10 ER-pos) and metastatic brain tumors. Subtype classification was performed using genefu. Protein changes in ER and HER2 (ERBB2) were confirmed by IHC. BrM-specific ERBB2 gains were corroborated in a publicly available dataset of 18 additional patient-matched cases (dbGAP phs000730.v1.p1). To test whether ERBB2 amplification and base pair mutation is metastasis-site specific, we further analyzed an expanded cohort of 7,884 breast tumors enriched for metastatic samples (52%) including liver (16.7%), lung (4.3%), bone (3.6%), and brain (2.0%) using comprehensive hybrid-capture sequencing of ERBB2.

RESULTS: 17/20 BrM retained the PAM50 subtype of the primary BrCa. Despite this concordance, 17/20 BrM harbored expression changes (< or > 2-fold) in clinically actionable genes including gains of FGFR4 (30%), FLT1 (20%), AURKA (10%) and loss of ESR1 expression (45%). The most recurrently upregulated gene was ERBB2, showing a >2-fold expression increase in 35% of BrM. 3 of 13 (23.3%) cases originally HER2-negative, and thus HER2-therapy naive, in the primary BrCa were IHC-positive (3+) in the paired BrM with an observed metastasis-specific amplification of the ERBB2 locus. In an independent dataset, 2 of 9 (22.2%) HER2-negative BrCa switched to HER2-positive with one BrM acquiring ERBB2 amplification and the other showing metastastic enrichment of the activating V777L ERBB2 mutation. Analysis of a large cohort of breast tumors (n=7,884) showed that across all organs ERBB2 amplification and/or base pair mutation was similar (p=0.18) between primary (13%) and metastatic disease (12%), however, a strong and significant enrichment was seen for BrM (primary 13% vs BrM 24%, p<0.0005).

CONCLUSIONS: Taken together, these results demonstrate that the majority (85%) of patient-matched BrM retain the intrinsic subtype of the primary cancer. However, despite this transcriptional similarity, alterations in clinically actionable genes are common, with BrM acquiring ERBB2 amplifications and/or base pair mutations at a frequency of ∼20%, even in HER2-therapy naive tumors. In a large cohort of primary and metastatic breast cancers, there is also a unique enrichment for ERBB2 alterations in BrM. This study provides a strong rationale to molecularly profile metastatic lesions to both better understand biological mechanisms of metastases and to perhaps refine therapeutic decision-making in advanced cancers.

Citation Format: Priedigkeit N, Hartmaier RJ, Chen Y, Vareslija D, Basudan A, Thomas R, Leone JP, Lucas PC, Bhargava R, Hamilton RL, Chmielecki J, Davidson NE, Oesterreich S, Brufsky AM, Young L, Lee AV. Breast cancer brain metastases show limited intrinsic subtype switching, yet exhibit acquired ERBB2 amplifications and activating mutations [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 PD1-05.

Abstract P6-11-03: A phase 2 open-label study of lucitanib in patients (pts) with FGF aberrant metastatic breast cancer (MBC)

BACKGROUND: Lucitanib is a potent, oral antiangiogenic tyrosine kinase inhibitor of Vascular Endothelial Growth Factor Receptors 1-3 (VEGFR1-3), Platelet-Derived Growth Factor Receptors alpha and beta (PDGFRα/β), and Fibroblast Growth Factor Receptors 1-3 (FGFR1-3). FGF aberrancies (amplification of FGFR1,or 11q[amplicon containing FGF ligands 3, 4, and 19]), are genomic alterations observed in over 20% of breast cancer pts and promote cancer proliferation and survival.

METHODS: MBC pts who had received at least 1 metastatic line of therapy were randomized 1:1 to 10 or 15 mg QD of lucitanib. Stratification was based on local assessment of FGF aberrancy; pts with both FGFR1 and 11q-amplified tumors were stratified as FGFR1 amplified. Central confirmation of FGFR1 or 11q amplification was done using Abbott FISH probes (FGFR1 or 11q copy number ≥ 6 and a ratio of FGFR1 or 11q to centromere ≥ 2). Investigator-assessed progression-free survival (PFS) was the primary endpoint. Secondary endpoints included objective response rate (ORR) per RECIST 1.1, disease control rate (DCR), duration of response (DR), and incidence of treatment-emergent adverse events (TEAE).

RESULTS: Enrollment completed in 3/2016; 178 pts that received at least 1 dose of lucitanib are included in this analysis (baseline characteristics in Table 1). Due to grade 3 hypertension in the 15 mg group (46% vs 37% in 10 mg group), enrollment to the 15 mg group was halted. Overall, most pts (97%) experienced at least 1 TEAE, with the most frequently (≥ 30%) occurring events being hypertension (73%), fatigue (48%), nausea (43%), hypothyroidism (40%), and headache (33%). Grade ≥ 3 TEAEs occurred in 66% of pts, with hypertension as the most frequent event (40%) followed by proteinuria and hyponatremia (both 6%). AEs were manageable with dose interruption or reduction, with approximately 8% of pts ending treatment due to an AE. Current median PFS is 3.5 mos (95% CI 2.8-4.6; range 0.62-12.95) and 2.6 mos (95% CI 1.8-2.9; range 0.82-18.87) respectively for the 10 mg and 15 mg treatment groups. No differences in clinical activity were observed by treatment group, FGF aberrancy, hormone receptor or HER2 status. Of the 168 evaluable pts, confirmed ORR was 3%; overall DCR was 27% (32% for pts in the 10 mg group compared to 20% for the 15 mg group); overall mean (standard deviation) DR of 3.3 (1.8) mos.

Baseline Characteristics 10 mg QD15 mg QD N=109N=69Age (years)Median5653Range27-8227-80SexFemale109 (100%)67 (97%)Male02 (3%)ECOG PSmissing5 (5%)2 (3%)051 (47%)30 (43%)153 (49%)37 (54%)Number of prior anticancer therapies in the metastatic setting> 332 (29%)21 (30%)3-648 (44%)32 (46%)> 629 (27%)16 (23%)Endocrine/HER2 statusmissing7 (6%)1 (1%)ER+ or PR+74 (68%)50 (73%)HER2+12 (11%)7 (10%)TNBC16 (15%)11 (16%)FGFR aberrancyFGFR1 amplified54 (49%)29 (42%)11q amplified31 (28%)24 (35%)FGFR1 and 11q amplified13 (12%)9 (13%)FGFR1 and 11q non-amplified11 (10%)7 (10%)

CONCLUSION: At 10 mg QD, lucitanib has modest activity with manageable toxicity in this heavily pretreated pt population. Future clinical development for lucitanib may focus on alternative biomarkers to identify sensitive tumors and rational combinations with other anti-cancer drugs.

Citation Format: Mayer IA, Arteaga CL, Nanda R, Miller KD, Jhaveri K, Brufsky AM, Rugo H, Yardley DA, Vahdat LT, Sadeghi S, Audeh MW, Rolfe L, Litten J, Knox A, Raponi M, Tankersley C, Isaacson J, Wride K, Morganstern DE, Vogel C, Connolly RM, Gradishar WJ, Patel R, Pusztai L, Abu-Khalaf M. A phase 2 open-label study of lucitanib in patients (pts) with FGF aberrant metastatic breast cancer (MBC) [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 P6-11-03.

Abstract P4-13-05: Safety results of the US expanded access program (EAP) of palbociclib in combination with letrozole as treatment of post-menopausal women with hormone-receptor-positive (HR+), HER2-negative (HER2-) advanced breast cancer (ABC) for whom letrozole therapy is deemed appropriate

Background: In the Phase I/II PALOMA-1 trial, a study in women with estrogen receptor (ER) positive advanced breast cancer (ABC) receiving initial therapy for their metastatic disease, combination of the CDK4/6 inhibitor palbociclib with letrozole improved progression free survival compared to letrozole. The aim of this open-label, single-arm EAP was to provide appropriate patients (pts) with ABC access to palbociclib pending marketing approval in the United States.

Methods: In the EAP, a total of 242 pts with HR+/HER2- ABC were treated at 42 sites in the US. Pts received palbociclib 125 mg/d (3 weeks on, 1 week off) in combination with letrozole 2.5 mg/d (continuous daily dosing) until disease progression, intolerable adverse event (AE), or commercial availability. AEs and serious AEs (SAEs) were assessed every cycle. Complete blood counts were assessed on day 1 and day 14 of the first two cycles and then at the beginning of each cycle thereafter. Tumor assessments were collected by investigators as per routine clinical practice.

Results: In this early analysis, we describe an initial cohort of 97 pts, with data collected during the first 3 months of study. Median duration of therapy was 31 days. Mean age was 62 yr (range 29-89). Baseline ECOG PS was 0, 1 or 2 in 36%, 49%, and 14% of pts, respectively. Common prior treatments (≥40% in any setting) included fulvestrant (59%), anastrozole (50%), paclitaxel (50%), exemestane (48%), cyclophosphamide (46%), tamoxifen (45%), doxorubicin (44%), and capecitabine (40%). Treatment-emergent AEs (TEAE; all grades) that occurred in greater than 10% of patients included neutropenia (28%), fatigue (19%), neutrophil count decreased (12%). Other hematologic TEAE rates included: anemia 9%, white blood cell count decreased 9% and thrombocytopenia 5%. All causality SAEs occurred in 6% of pts at the rate of 1 patient each for ankle fracture, constipation, disease progression, febrile neutropenia, lung infection, and pancytopenia. The rate of palbociclib dose reduction due to a TEAE was 4%. The rate of temporary delay of palbociclib due to TEAE was 36%. TEAEs leading to permanent discontinuation occurred in 1% of pts (Grade 3 nausea & vomiting). Grade 3 or 4 TEAEs were reported in 42% of pts, including neutropenia (Grade 3: 24%, Grade 4: 2%). There were no fatal outcomes due to TEAEs. This early data will be updated for final conference presentation to include the complete patient cohort and updated duration of therapy on study drug.

Conclusions: In this population of pts with HR+/HER2- ABC, palbociclib in combination with letrozole was well tolerated. Analysis of this early cohort indicates that the safety profile was consistent with that seen in the PALOMA-1 trial.

Clinical trial information: NCT02142868

Funding Source: Pfizer.

Citation Format: Stearns V, Smith II JW, Patel R, Lu D, Perkins JJ, Cotter MJ, Brufsky AM. Safety results of the US expanded access program (EAP) of palbociclib in combination with letrozole as treatment of post-menopausal women with hormone-receptor-positive (HR+), HER2-negative (HER2-) advanced breast cancer (ABC) for whom letrozole therapy is deemed appropriate. [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 P4-13-05.

Abstract P6-08-02: Developing in vitro models of ductal carcinoma in situ from primary tissue

BACKGROUND: Because there are currently no reliable predictors for progression of ductal carcinoma in situ (DCIS) to invasive disease, nearly all patients receive aggressive therapy, leading to over-treatment in many cases. Few in vitro models for studying DCIS progression have been developed. We report here the successful culture and expansion of primary DCIS from surgical specimens using a conditional reprogramming protocol.

MATERIALS AND METHODS: From 2/2014 to 4/2015, patients with percutaneous core needle biopsy demonstrating DCIS were enrolled in a tissue banking protocol after informed consent was received. Under supervision of the surgical pathologist, fresh tissue measuring between 5-15 mm in length was taken from lumpectomy or mastectomy specimens. Tissue was divided such that half was mechanically and enzymatically dissociated and then cultured in medium conditioned by irradiated mouse fibroblasts and supplemented with rho-associated protein kinase (ROCK) inhibitor, and the second half, known as the "mirror image" remained as part of the clinical specimen.

RESULTS: Of 49 consented patients, mean age was 59 ± 10 years. 7 were excluded due to final pathology not consistent with DCIS: 4 upstaged to invasive ductal cancer, 2 had microinvasion and 1 showed pleomorphic lobular carcinoma in situ. Of the remaining 42, 9 were failures: 5 tissues were not received in lab and 4 cases were received, but no cells grew in culture. Of the remaining 33 cases of DCIS, 70% (n=23) and 27% (n=9) were nuclear grade 2 and 3 respectively. 91% (n=30) were ER-positive, with H-score ranging between 4 and 300. 19 (58%) were expanded in cell culture for up to two months in culture, and 14 were frozen immediately after mechanical dissociation for future growth. The 19 cell cultures could be cryopreserved and expanded. The cultures are almost exclusively composed of cytokeratin 8- and EpCAM-positive luminal cells and cytokeratin 14-, cytokeratin 5-, and p63-positive basal mammary epithelial cells, suggesting maintenance of heterogeneity in vitro. Furthermore, as assessed by luminal and basal marker expression, these cells retain their cellular identities both in the "conditionally reprogrammed" proliferative state and when conditioned media and ROCK inhibitor were withdrawn. When grown to 100% confluency, the cultures appear to organize into luminal and basal layers as well as luminal compartments surrounded by basal cells.

CONCLUSION: Primary cultures of DCIS derived directly from patient tissues may serve as in vitro models for the study of DCIS.

Citation Format: McAuliffe PF, Brown DD, Oesterreich S, Lee AV, Johnson RR, McGuire KP, Davidson NE, Brufsky AM, Dabbs DJ. Developing in vitro models of ductal carcinoma in situ from primary tissue. [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 P6-08-02.

Abstract P1-11-06: The experience of caregivers of women with metastatic breast cancer: Insights from the Make Your Dialogue Count survey

Introduction: Caregivers of patients with breast cancer have demonstrated persistent unmet needs, including reduced physical and psychosocial well-being. This may be particularly acute in caregivers of patients with metastatic breast cancer (MBC), whose ongoing treatments and increasing disability with disease progression offer particular challenges. While prevalence of MBC is currently unknown, caregivers of women with MBC represent a sizable group.

Objective: To explore the emotional, psychological, and social impact on caregivers of patients with MBC and to identify gaps in communications between patients and their caregivers and oncologists.

Methods: The "Make Your Dialogue Count" survey was conducted online, by paper, and by telephone (June-August 2014) among caregivers in the United States (age ≥18 y) who attended ≥50% of doctor visits of women with MBC (age ≥21 y). Survey responses were single- or multiple-response, numeric text, or rated on a 4-point Likert scale. Caregiver data were unweighted and representative only of those responding. Statistically significant differences between groups were determined by standard t-test of column proportions and means at the 95% confidence level.

Results: 234 caregivers responded; 73% were men, 44% were the patient's spouse/partner, and 27% were nonwhite. Median age was 44 y. The caregivers' loved ones had a median time from initial breast cancer diagnosis of 44 months prior, and 51% had recurred after early breast cancer. Most caregivers (76%) considered themselves to be extremely or very involved in treatment decisions, but a sizable fraction of caregivers were unaware of the HR (20%) or HER2 (29%) status of the patient's cancer, indicating a lack of basic information needed for informed decision-making. While most (93%) said they felt comfortable speaking with the treatment team about MBC treatment, 41% reported communication barriers. Over half of caregivers (53%) felt that nobody understands what they're going through, and most (86%) reported that their lives had been negatively affected in some way (such as sleep habits, relationships and social life, hobbies and personal time, and financial stability and employment). Most caregivers considered caregiving to be an emotional (77%) and physical (56%) burden and 36% felt unappreciated. At the time of initial MBC diagnosis, 69% of caregivers felt it was important/very important for their loved one's doctor to refer them to support services, but only 25% of caregivers reported receiving such a referral. Subgroup analysis of caregiver's gender revealed some differences in responses relating to communications with oncologists, treatment experience, and emotional impact.

Conclusions: While committed to their roles, these caregivers often found their role to be a physical and emotional burden, and many reported feeling isolated and unappreciated for their caregiving. Our findings indicate a strong need for support services specifically tailored to caregivers, including outreach to address emotional, financial, and practical needs stemming from caring for a loved one with MBC. They also indicate a need for improved disease and treatment information exchange between caregivers, patients, and healthcare providers.

Citation Format: Mayer M, Sampayo I, Bell Dickson R, Citron ML, Brufsky AM. The experience of caregivers of women with metastatic breast cancer: Insights from the Make Your Dialogue Count survey. [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 P1-11-06.

Abstract P6-11-08: Risk of CNS relapse following adjuvant trastuzumab therapy – Updated literature-based meta-analysis

Background: Randomized trials of adjuvant trastuzumab in HER2-positive early breast cancer observed an increased risk for central nervous system (CNS) as site of first relapse. A meta-analysis of three trials with a total of 6752 patients followed up for a median of 2 years found an 82% increased risk for CNS relapse as first disease free survival (DFS) event with adjuvant trastuzumab use. It is thought that the greater risk for CNS as first relapse site is due to the lack of penetration of trastuzumab through the blood-brain barrier combined with better disease control in other visceral sites rather than the drug itself predisposing patients to CNS disease. Therefore, we hypothesize that the effect size of this association will decrease with increasing duration of follow-up.

Methods: A comprehensive literature search was performed. Updated results from the three randomized trials of adjuvant trastuzumab were identified. The NSABP B-31 and the NCCTG N9831 trials compared four cycles of doxorubicin and cyclophosphamide (AC) followed by four cycles of Paclitaxel (T) with the same regimen combined with trastuzumab for a year. The HERA trial compared one or two years of adjuvant trastuzumab with observation. We abstracted the number of CNS relapse events in these trials and performed a meta-analysis with fixed-effect model using Mantel-Haenzel method.

Results: Out of a total of 7456 patients included in the analysis, CNS DFS events occurred in 98 patients receiving trastuzumab compared to 68 patients in the control group over a median follow-up period of 4 years. We found a 43% increased risk for CNS relapse as first DFS event in patients who received adjuvant trastuzumab compared to the group that did not receive the drug (RR 1.43; 95% confidence interval 1.06, 1.95). We found no inconsistency in risk ratio estimates between the three trials (I2 = 0%).

Discussion: Adjuvant trastuzumab is associated with a higher risk for CNS as first relapse site despite an increase in duration of follow-up. The reduction in effect size from the previously reported 82% increased risk observed with a 2 year follow-up period, to 43% with 4 years of follow-up adds to the body of evidence that the drug itself does not predispose a patient to CNS recurrence. On the contrary, the reduction in effect size could also be attributed to the crossover study design in HERA trial, where nearly 50% of patients in the control group eventually received trastuzumab. In summary, we propose that the adjuvant trials of the newer HER2 targeted therapy should be designed to look into CNS disease as not only first site of recurrence but also gather additional data on all CNS recurrences to further elucidate the mechanism of CNS disease with HER2 directed therapy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-11-08.

Abstract P6-07-02: Prediction of oncotype DX® recurrence score using pathology generated equations

BACKGROUND: Oncotype DX® is a quantitative reverse transcription polymerase chain reaction based assay that has been shown to have prognostic and predictive value in estrogen receptor (ER) positive breast cancers. The result is reported as a recurrence score (RS) ranging from 0–100, divided into low risk (<18), intermediate risk (18–30), and high risk (≥31) categories. Prior studies have shown that RS is influenced by ER and progesterone receptor (PR) expression, HER2 status, proliferation index, and tumor grade. Our pilot study showed that RS can be predicted by an equation incorporating standard morpho-immunohistologic variables (referred to as Original Magee Equation; Mod Pathol. 2008;21:1255–1261).

METHODS: Using a dataset of 817 cases, we formulated three additional equations to predict the RS category for an independent set of 255 cases. Three models were built based on different hypotheses and data availability and are represented below.

New Magee Equation 1 (nME1): RS = 15.31385 + Nottingham score*1.4055+ ER H-score*(−0.01924) + PR H-score*(−0.02925) + (0 for HER2 negative, 0.77681 for equivocal, 11.58134 for HER2 positive) + Tumor size*0.78677 + KI67 index*0.13269.

New Magee Equation 2 (nME2): RS = 18.8042+ Nottingham score*2.34123 + ER H-score*(−0.03749) + PR H-score*(−0.03065) + (0 for HER2 negative, 1.82921 for equivocal, 11.51378 for HER2 positive) + Tumor size*0.04267.

New Magee Equation 3 (nME3): RS = 24.30812+ ER H-score*(−0.02177) + PR H-score*(−0.02884) + (0 for HER2 negative, 1.46495 for equivocal, 12.75525 for HER2 positive) + KI-67*0.18649.

RESULTS: The concordance between the risk category of oncotype DX® and our equations was 55.8%, 59.4%, and 54.4% for nME1, nME2, and nME3 respectively. With exclusion of the intermediate risk categories for both the actual RS and estimated RS, the concordance for each equation increased to more than 95%, reflecting the very low two step discordance (100% {76/76}, 98.6% {75/76}, and 98.7% {79/80} for nME1, nME2, and nME3 respectively). Even when the estimated RS fell in the intermediate category with any of the equations, the actual RS was either intermediate or low in more than 85% of the cases. The Pearson correlation coefficient between estimated and actual RS was similar for each of the equations (0.61661, 0.60386 and 0.59407 for nME1, nME2 and nME3, respectively).

CONCLUSIONS: Any of the 3 equations can be used to estimate the RS depending on available data. If the estimated RS is clearly high or low, the oncologists should not expect a dramatically different result from oncotype DX®, and the oncotype DX® test may not be needed. Conversely, an oncotype DX® result that is dramatically different from what is expected based on standard morpho-immunohistologic variables should be thoroughly investigated.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-07-02.

P1-08-22: Treatment Patterns and Clinical Outcomes in Elderly Patients with HER2−Positive Metastatic Breast Cancer from the registHER Observational Study

Background: Data are lacking regarding treatment patterns and outcomes in elderly patients (pts) with HER2−positive (HER2+) metastatic breast cancer (MBC).

Methods: registHER is a large, observational cohort of pts with HER2+ MBC diagnosed within 6 months of enrollment. Pts (N=1,001) were followed until death, disenrollment, or June 2009 (median follow-up 27 months). In these analyses, pts were stratified into three groups based on age at MBC diagnosis: younger (<65 years), older (65-74 years), elderly (≥75 years). For Progression Free Survival (PFS) and Overall Survival (OS) analyses of 1st-line trastuzumab (T) vs. no T, older and elderly pts were combined due to small number of events in elderly. Hierarchical multivariate analyses were adjusted for baseline characteristics and treatments.

Results: ER/PR status was similar across age groups (Table 1). Elderly pts with HER2+ MBC had higher rates of underlying cardiovascular disease (CVD) than younger or older pts. In pts receiving T-based 1st-line treatment, elderly pts were less likely to receive chemotherapy (C), and more likely to receive T alone or combined with hormone therapy (HT). Central nervous system (CNS) events decreased with increasing age. In T-treated pts, incidence of left ventricular dysfunction (grade ≥3) was higher in elderly pts (3/63 [4.8%]) than in younger (21/746 [2.8%]) or older pts (2/134 [1.5%]). Across age groups, unadjusted median PFS (months) was significantly higher for pts treated with T in 1st-line than those who were not (<65 years T: 11.0; <65 years no T: 3.4; ≥65 years T: 11.7; ≥65 years no T: 4.8). In pts <65 years, unadjusted median OS (months) was significantly higher in T-treated pts; in pts ≥65 years, median OS was similar (<65 years T: 40.4, <65 years no T: 25.9; ≥65 years T: 31.2, ≥65 years no T: 28.5). In multivariate analyses, T in 1st-line was associated with significant improvement in PFS across age (Table 2). In OS, significant improvement was observed for pts <65 years; results were suggestive for pts ≥65 years.

Conclusions: Elderly pts (≥75 years) with HER2+ MBC in registHER had higher rates of underlying CVD than younger counterparts and received less aggressive treatment, including less 1st-line T. These population-based, real-world data suggest improved PFS with T as 1st-line therapy across all age groups.

P4-11-05: Association between Bisphosphonate Use in Metastatic Breast Cancer (MBC) and Overall Survival

Background

Pre-clinical studies on bisphosphonates in breast cancer have suggested an anti-tumor effect in addition to its bone protective role. However, randomized controlled trials of bisphosphonates versus placebo have found little evidence of increased overall survival (OS) in MBC. We conducted a retrospective single institution cohort study of MBC patients to evaluate the association between bisphosphonate use and overall survival.

Methods: Baseline demographic and tumor specific data were collected on newly diagnosed MBC patients between January 1998 and December 2009. Other variables included the number and sites of each metastasis, use of baseline neoadjuvant and adjuvant chemotherapy, and use of hormonal therapy. Bisphosphonate use was defined as present if it was administered for a period of at least 3 months in the metastatic setting. Overall survival was determined from the date of diagnosis of first metastatic disease. Survival analysis was performed using the Kaplan-Meier method and Cox proportional-hazards model.

Results: Data were available on 737 patients with MBC, of whom 434 died during a median follow-up of 2 years; median age was 50.3 years. 92% of patients were Caucasian; 32% were both ER and PR-negative; and 31% were HER2−positive. Over 67% of MBC patients had bone metastasis and nearly 80% received bisphosphonates. Multivariate analysis found an overall survival benefit for bisphosphonate use, with a hazard ratio of 0.63 (95% confidence interval: 0.48−0.84; p<0.002), when adjusted for variables with significant effect on survival on univariate analysis and other known prognostic variables. These variables include age, stage at diagnosis, race, hormone receptor status, HER2 status, and number of metastatic sites, presence of bone metastasis and the use of adjuvant therapy. The administration of adjuvant therapy did not yield a significant survival advantage in the analyses.

Conclusion: This retrospective cohort study provides evidence for an OS benefit with the use of bisphosphonates in MBC even after controlling for other significant prognostic factors.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-11-05.

P4-17-06: Prognostic Role of Triple Negative Subtype in Breast Cancer Patients with Brain Metastases

Background

Metastatic breast cancer (MBC) patients with brain metastases (BM) have a poorer prognosis compared to patients with metastases to sites such as bone or other visceral organs. The role of breast cancer subtypes such as triple negative (TN) status and its relationship with other known prognostic factors have not been well delineated in the context of metastatic disease to the brain. We conducted a retrospective single institution cohort study of MBC patients with BM to evaluate the association between TN subtype and overall survival from the diagnosis of BM.

Methods: Baseline demographic and tumor specific data including ER, PR and HER2 status were collected on newly diagnosed MBC patients between January 1998 and December 2009. Overall survival was determined from the date of diagnosis of BM. Survival analyses were performed using the Kaplan-Meier method and Cox proportional-hazards model.

Results: Data were available on 186 MBC patients with BM, of whom 156 died during a median follow-up of 10.2 months from the diagnosis of BM; median age was 47.9 years. 91% of patients were Caucasian; 25.3% had triple negative disease. Median survival from the period of diagnosis of BM in patients with triple negative disease was 7 months (Interquartile range, IQR: 3–13) as compared to 11 months (IQR: 5–22) in patients who were HER2−positive or ER/PR-positive. Multivariate analysis found a higher risk of death after BM for TN disease subtype, with a hazard ratio for death of 2.89 (95% confidence interval: 1.89−4.44; p<0.001), when adjusted for variables such as age and stage at initial diagnosis of breast cancer, race, the number of metastatic sites, and the use of metastatic chemotherapy. The administration of metastatic chemotherapy had a significant survival benefit in the analyses, with a hazard ratio for death of 0.52 (95% CI: 0.27−0.99; p=0.048).

Conclusion: This retrospective cohort study in MBC patients with BM provides evidence for a greater risk of death in those with TN disease as compared to HER2−positive or ER/PR-positive subtypes even after adjusting for other prognostic factors.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-17-06.

Long-term treatment with intravenous bisphosphonates in metastatic breast cancer (MBC)

1035

Background: Intravenous bisphosphonates (IV BPs) are safe and effective in reducing skeletal related events in MBC. The effects of IV BPs after 24 months of therapy are unknown. The incidence of osteonecrosis of the jaw (ONJ) and renal insufficiency (RI) among women with MBC receiving >= 24 months of IV BPs is also poorly defined. We studied the long term effect of IV BPs in a cohort of women with MBC. Methods: We maintain an ongoing prospective database of >600 women with MBC diagnosed and treated at our institution from January 1999. A long-term cohort (LTC) of 159 women with metastatic breast cancer to bone treated for >= 24 months with pamidronate (n = 9), zoledronic acid (n = 110), or both (n = 40) was identified. A control cohort (CC) of 62 women with MBC to bone treated with IV BPs for 12–23 months was also identified. RI was defined as an increase in serum creatinine (scr) of > 0.5 mg/dl or an absolute level of scr >1.5mg/dl; ONJ was diagnosed by dental consultation. Results: Median follow-up of the LTC was 39 months (range 24–99) months. Median overall survival in this cohort was 43 months (range 24–114). The vast majority of women in the LTC (140/159, 88.1%) continued to receive IV BPs at standard dose every 3–4 weeks. The incidence of ONJ in the LTC was 6/159 (3.8%), after a mean 42.2 treatment cycles, with a median time to ONJ of 44 months. Three of six patients with ONJ (50%) underwent surgical resection, and 3/6 (50%) were managed conservatively, and 3/6 (50%) resumed IV BPs after a mean 12 month hold. The incidence of RI (all pts had baseline scr < 1.4 mg/dl) in the LTC was 19/159 (11.9%), occurring after a mean 43.4 treatment cycles, with a median time to RI of 43 months. Eleven of 19 patients (57.9%) recovered to baseline scr and 7/19 (36.7%) patients showed partial recovery. Seventeen of 19 patients (89.4%) were able to resume therapy after temporary discontinuation, decreasing the dose, or increasing the interval of the IV BP. Incidence of ONJ in the CC was 1/62 (1.6%) and RI in the CC was 6/62 (9.7%). Conclusions: Long term (>=24 month) IV BP use in MBC is well tolerated and safe, with relatively low incidence of ONJ and RI. Most patients were able to resume IV BP therapy after a therapy hold without further complication.

No significant financial relationships to disclose.

Breast cancer molecular classification using immunohistochemical surrogate markers predicts response to neoadjuvant chemotherapy

Abstract #6071

Complete pathologic response (pCR) to neo-adjuvant chemotherapy (NACT) is seen in 45% of "ERBB2" and "basal-like" group of tumors using gene expression profiling (Rouzier et al. Clin Cancer Res. 2005;11:5678-5685).&#x2028; We hypothesized that a similar response could be predicted using the immunohistochemical (IHC) surrogate markers estrogen receptors (ER), progesterone receptors (PR) and HER2. ER and PR were scored using a semi-quantitative scoring method (modified "H-score") with a dynamic range of 0-300. HER2 was considered positive only if 3+ by IHC or amplified (HER2 to chromosome 17 ratio of &gt;2.2) by FISH. These markers were used to classify 358 tumors treated with NACT into the following 6 groups: luminal A (LUMA; ER score 200 or higher, HER2 negative); ERBB2 (ER and PR score 10 or less, HER2+); triple negative (TN; ER and PR score 10 or less, HER2 negative); luminal A-HER2 hybrid (LAHH; ER score 200 or higher, HER2+); luminal unclassified HER2 negative (LUHN; ER or PR score 11-199, HER2 negative); luminal unclassified HER2 positive (LUHP; ER or PR score 11-199, HER2+). pCR was defined as absence of invasive carcinoma in the post therapy resection specimen along with lack of carcinoma within regional lymph nodes.&#x2028; pCR and average tumor size reduction was much higher in ERBB2 and TN group of tumors compared to the other classes (p&lt;0.05).&#x2028; &#x2028; Trastuzumab was part of NACT regimen in 6 ERBB2 tumors of which 5 (83%) showed pCR. In contrast, 10 patients with LUHP and LAHH tumors (ER/PR+ and HER2+ tumors) received trastuzumab, of which none showed pCR.&#x2028; Conclusions: pCR to NACT is generally limited to "ERBB2" and "TN" tumors. This response can be predicted with similar (to expression profiling) accuracy using IHC surrogate markers. Sub-division of ER+ tumors into LUMA, LUHN, LAHH, and LUHP demonstrates subtle differences between these groups with respect to pCR and tumor size reduction and confirms that NACT is less effective in all ER+ tumors. Among all HER2+ tumors, trastuzumab treatment is much more effective in ERBB2 tumors.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6071.

registHER: Patient characteristics, treatment patterns, and preliminary outcomes in patients with HER2-positive (HER2+), hormone receptor-positive (HR+) metastatic breast cancer (MBC)

21007

Background: Approximately 50% of HER2+ breast cancers are HR+, however, the interaction between HER2 and HR is not completely understood. Patients with HR+/HER2+ or HR-/HER2+ tumors treated with trastuzumab + chemotherapy (CT) achieve similar clinical benefit. Retrospective analyses suggest that HER2+ tumors are resistant to hormone therapy (HT), particularly anti-estrogens, possibly due to estrogen receptor /HER2 interactions and quantitatively lower HR expression in HER2+/HR+ tumors. Conducting randomized clinical trials in HER2+/HR+ MBC is challenging given the small patient population. Methods: registHER is a prospective observational study of approximately 1000 patients with newly diagnosed (<6 months) HER2+ MBC treated in community or academic settings. Baseline characteristics and treatment patterns in patients with HR+ vs HR-, HER2+ MBC receiving first-line therapy were studied in this analysis. The influence of adjuvant HT on disease-free intervals (DFI) from time of diagnosis and MBC treatment selection in patients with HR+/HER2+ tumors was examined. Results: Of 976 patients with HER2+ MBC and recorded tumor HR status, those with HR+ MBC (54.9%) tended to be white (81.7% vs 77.0%), were more likely to have bone only metastases (18.1% vs 6.4%), less likely to have CNS metastases (2.8% vs 8.2%), and have fewer metastatic sites at diagnosis (49.1% vs 43.2%) than those with HR- MBC. Of patients with HR+ MBC, who were stage I- III at initial diagnosis, 51.3% received adjuvant HT, of which 73.2% received tamoxifen. Median DFI was 48.8 vs 29.4 mo for patients receiving tamoxifen vs an aromatase inhibitor. First-line MBC treatment regimens included: HT only (13.8%); HT + trastuzumab (8.4%); HT + trastuzumab + CT (6.2%); trastuzumab only (6.0%); CT only (11.0%); trastuzumab + CT (53.5%). Analyses of progression-free survival by HR status and first-line treatments (HT only, trastuzumab ± HT or ± CT), are ongoing and will be described. Conclusions: registHER represents the largest dataset of patients with HER2+/HR+ MBC and provides a unique opportunity to characterize treatment patterns, efficacy and safety, and the natural history of this subset of breast cancer patients.

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Immunity to MUC1 in pancreatic and breast cancer

21166

Background: A cancer vaccine composed of MUC1 loaded DCs was effective at inducing tumor rejection in MUC1 transgenic mice. We present data from a phase IB clinical trial of the same vaccine in patients with pancreatic cancer. Preliminary analysis of this trial was reported at ASCO 2004,# 2578. Our current studies based on the results of this trial explore the importance of anti-MUC1 immunity in patients with early breast cancer, aiming to create a strong rationale for boosting these responses with vaccination in adjuvant settings. Data from both studies will be presented. Methods: The objectives of the vaccine trial were to evaluate toxicity of the vaccine, its ability to boost immunity and clinical outcome. Patients received autologous DC loaded with MUC1 100mer peptide every 3 weeks for a total of 3 doses and a booster dose 6 months later. Blood samples were obtained prior to each dose and at various times post vaccination. For the current study, 100 preoperative/pretreatment peripheral blood samples have been collected prospectively from patients with early breast cancer. Multiple immune parameters are being assessed in each group. Results: Data from extensive immune response analyses of the pancreatic cancer vaccine will be presented in detail at AACR 2007, and summarized here to provide the basis and comparison for our ongoing studies in early breast cancer. 4/12 patients in the vaccine study are alive without recurrence at three years. Even though effector and regulatory T cell responses were detected in several patients, none could be correlated with long-term survival. Several patients had anti-MUC1 antibody responses that remained stable following vaccination, which also did not correlate with survival. Ongoing studies in early breast cancer are assessing the potential differences in the quality of anti-MUC1 responses between early and late stage disease. Conclusions: In the setting of advanced disease, such as pancreatic cancer, the vaccine appears to have an effect on keeping regulatory T cells low and cellular and humoral immunity stable, without causing any significant toxicity. Ongoing studies in early breast cancer are aiming to define the immune parameters that might predict increased survival.

No significant financial relationships to disclose.

Phase II study of gemcitabine (Gem) and trastuzumab (T) combination therapy in first line metastatic breast cancer (MBC) patients (pts) with HER2 overexpression

10591

Background: Phase III studies have demonstrated that the addition of T to chemo is associated with higher response rates (RR), improved time-to-progression (TTP) and improved overall survival in pts with metastatic HER2+ tumors. The greatest benefit from T-based therapy is found in women with pronounced HER2 overexpression (FISH+ or IHC 3+). Preclinical models suggest that Gem+T appear to be additive or synergistic. The present study was designed to determine overall RR (primary endpoint), TTP, OS and the toxicity profile of the combination of Gem+T as first-line therapy for MBC pts. Methods: Pts with measurable HER2-overexpressing (IHC 3+ or FISH+) MBC, no prior chemo in the metastatic setting (adjuvant was allowed), adequate end-organ function and PS 0–2, received Gem 1,250 mg/m2 on days 1 and 8 and T on day 1 (8 mg/kg over 90 min on cycle 1, then 6 mg/kg over 30 min on subsequent cycles) of a 21-day cycle, until progressive disease or undue toxicity. A Simon’s optimal two-stage design was used with a total sample size of 66 (25 patients treated in the first stage and 41 additional patients in the second stage). Results: Sixty-six patients have been treated and results are available for sixty-four patients. Median age: 53 years (range 34–83); Race: Caucasian/Other 88%/12%. ER status positive/negative: 53%/47%. HER2 status IHC 3+/FISH+: 58/20 pts.; ECOG PS 0/1/2: 66%/30%/3%; Prior adjuvant therapy: Chemo 39 pts (prior anthra 31, prior taxane 21), Hormonal 32 pts (6 adj, 18 met, 8 both). Total number of cycles = 396; median = 6 (range 1–21). Toxicity was generally modest. Grade 3/4 neutropenia occurred in 11 pts (17%)/7 pts (11%); thrombocytopenia 3pts (5%)/1pt (2%), anemia 3 pts (4.7%)/ 0 pts, and 2 pts with grade 4 transaminase elevation, grade 3 elevated ALT 6 pts (9.4%); no other grade 4 toxicities were recorded. One pt with prior anthra exposure had a grade 2 decrease in left ventricular ejection fraction; no symptomatic cardiac toxicity was recorded. Best Overall RR assessment (N = 64): CR 8 (12.5%), PR 26 (40.6%) for an overall RR of 53.1% (95% CI: 40%-66%). TTP median 6 mo (95% CI: 4.4 -9.7 mo). Survival data not mature at this time. Conclusions: The combination of Gem+T in front-line MBC shows a high response rate with modest toxicity.

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Symptom distress, quality of life and challenges of illness according to race and income in women with metastatic breast cancer

8609

Background: Response to a diagnosis of metastatic breast cancer (MBC) may vary according to race and income. The aims of this study were: 1) to identify quality of life, symptom distress and challenges of illness during MBC treatment and 2) to determine if these variables differ according to race and income. Methods: The study was a 2×2 prospective design conducted at an urban breast cancer center. Women with MBC were categorized into four groups based on race and income: white low (WL), white high (WH), African American high (AAH) and African American low (AAL). Instruments were 1) Symptom Distress Scale (SDS), (higher scores /worse distress) 2) Functional Assessment of Cancer Therapy (FACT), (higher scores/better QOL) and a 3) semi structured interview assessing patient perspectives of MBC. Interview analysis utilized grounded theory. Results: Preliminary results are for 51 women. Mean age was 58.2 years, with mean 24 months since MBC diagnosis. Quantitative data indicated worse quality of life in AA than white women. (P=0.06), with AALI women exhibiting worse symptom distress (P=0.03) as compared to white women. Qualitative data (n=48) corroborated quantitative data. The most prevalent themes among all sociodemographic groups were of hope (33/48 - 69%), faith (28/48 - 58%) and progressive loss (29/48, 60%). Each racial/economic delineation expressed unique themes: AALI talked about physical (7/7,100%)and social distress (6/7, 86%) as well as uncertainty regarding “whether treatment was worth it” (6/7 - 86%). WLI women verbalized an overall optimism, describing themselves as “lucky” (6/14 - 43%), with minimization of symptoms (10/14 - 71%). WHI women articulated a sense of betrayal at their progressive illness (9/20 - 45%) and fear of physical and economic dependence. Conclusion: Race and economic delineation brings unique symptom experience, quality of life and patient perspective to the metastatic breast cancer experience. These findings will advise tailored intervention.

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No significant financial relationships to disclose.

registHER: Baseline characteristics of a cohort of HER2-positive metastatic breast cancer (MBC) patients

20095

Background: HER2 is amplified in 25% of breast cancers and is associated with poor survival. registHER captures the natural history, treatment patterns and outcomes in 1000 newly-diagnosed HER2-positive MBC patients (pts) throughout the U.S. This observational study recruits pts in both academic and community centers. Methods: This ongoing prospective cohort study collects clinical, pathologic and treatment data at enrollment, quarterly until death, loss to follow-up or 3 years after the last enrollment. We describe baseline pt and clinical characteristics in registHER compared with HER2-positive MBC pts in the phase III pivotal trial (Slamon DJ, et al. N Engl J Med. 2001;344:783–792). Results: Between December 2003 and September 2005, 813 eligible pts were enrolled at 280 study sites. Most pts were seen at community-based (76%) vs academic (18%) clinics; a few pts did not fall into either category (6%). A comparison of baseline characteristics is shown below. Conclusions: registHER pts tended to have a shorter disease-free interval and more estrogen receptor positive disease than pts in the pivotal trial. Reasons for these differences could reflect trial referral and/or diagnostic testing differences. Fewer registHER patients were white, but other characteristics were similar between the two groups. These findings support the hypothesis that observational studies describe a broad patient population which may not exactly duplicate clinical trials. Within registHER, there was some variation between academic vs community clinics (eg. nodal status and adjuvant therapy). Treatment pattern analyses are ongoing.

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Comprehensive transcript analysis in small quantities of mRNA by SAGE-lite

Serial analysis of gene expression (SAGE) is a powerful technique that can be used for global analysis of gene expression. Its chief advantage over other methods is that SAGE does not require prior knowledge of the genes of interest and provides quantitative and qualitative data of potentially every transcribed sequence in a particular tissue or cell type. Furthermore, SAGE can quantify low-abundance transcripts and reliably detect relatively small differences in transcript abundance between cell populations. However, SAGE demands high input levels of mRNA which are often unavailable, particularly when studying human disease. To overcome this limitation, we have developed a modification of SAGE that allows detailed global analysis of gene expression in extremely small quantities of tissue or cultured cells. We have called this approach 'SAGE-Lite'. This technique was used for the global analysis of transcription in samples of normal and pathological human cerebrovasculature to study the molecular pathology of intracranial aneurysms. These samples, which are obtained during operative surgical repair, are typically no bigger than 1 or 2 mm and yield <100 ng of total RNA. In addition, we show that SAGE-Lite allows simple and rapid isolation of long cDNAs from short (15 bp) SAGE sequence tags.