Abstract P5-03-11: Targeted disruption of transcriptional effector GLI2 attenuates breast tumor growth and metastasis

We reported that transcriptional regulation by the major Hedgehog (HH) pathway effector GLI2 in mammary gland stromal cells coordinates a hormone-responsive niche signaling program that directs epithelial stem cell activity during puberty [Zhao, et al., Science. 2017 Apr 21;356(6335)]. HH signaling is a key growth pathway in human carcinogenesis. The first targeted therapies aimed at G-protein coupled receptor Smoothened (SMO) resulted in rapid acquired resistance, underscoring the need for developing new HH pathway-targeting therapies downstream of SMO. In BC GLI-dependent transcription may involve a non-receptor-based mechanism of GLI2 activation involving cross-talk from other signaling pathways such as TGFß54, PI3K55,56, Wnt, or NF-κB. Accordingly, we investigated the role of HH pathway and its transcriptional effectors using the MMTV-PyMT BC mouse model. Development of mammary tumors arising proceeds through neoplastic lesions ranging from carcinoma in situ (10-12 weeks) to highly invasive ductal carcinoma with high incidence of pulmonary metastasis at 16-18 weeks. Epithelial ablation of GLI2 dramatically reduced tumor progression. Cre recombinase under control of the Ck14 promoter to genetically ablate GLI2 in basal cells of the mammary gland thus dramatically attenuated metastasis despite continued (albeit reduced) formation of primary tumors. In human BC, we applied Bayesian methods to gene expression data to identify metastatic BC with HH pathway activation. Kaplan-Meier analysis demonstrated significantly worse progression-free survival in patients with HH pathway activity (Log-rank p = 0.0013). Next, we analyzed 1294 BC samples, stratified according to HH activity, using the HH probability as a continuous score ranging between 0 and 1, univariate Cox regression analysis supports the hypothesis that HH activity in BC is a risk factor for relapse after surgery, HR = 2.45 (95% CI: 1.67 – 3.61, p = 2.72e-6). There is also a significant difference in survival between HH-actives and HH-inactives (Log-rank p = 3.91e-4), suggesting a pathogenic role of GLI activation in BC progression and metastasis. Arsenic trioxide (ATO), inhibits HH pathway activity by de-stabilizing the GLI transcriptional effectors of HH signaling, likely due to arsenic displacement of zinc within the DNA-binding zinc fingers of GLI proteins. ATO treatment of BC cell lines resulted in dose-dependent cell growth inhibition (Alamar Blue) and induction of apoptosis (PARP cleavage and Annexin V expression) at clinically achievable concentrations. In NSG mice with orthotopic transplant of 3e5 SU151 human BC PDX, with strongly positive GLI-active signature, daily IP injection of 10mg/kg ATO resulted in marked tumor growth inhibition in vivo (2.75-fold smaller tumor diameter vs. PBS vehicle controls, P= 0.006; 55d vs. 17d to reach 1.5 cm criterion for ATO vs. vehicle). We conclude the major HH pathway transcriptional effector GLI2 coordinates a transcriptional program with a central role in BC growth and metastasis in a significant subset of BC, and that systemic treatment with ATO (new oral formulation in commercial development), will reduce metastatic progression and improve clinical outcomes in patients whose tumors harbor a GLI-active transcript signature.

Citation Format: Beachy P, Cai S, Ma Y, Hatakeyama J, Zhao C, Stoffels M, Verhaegh W, van de Stolpe A, Pegram M. Targeted disruption of transcriptional effector GLI2 attenuates breast tumor growth and metastasis [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 P5-03-11.

Abstract P3-03-06: Characterization of HER2-positive breast cancer (BC) cells selected for tolerance to trastuzumab-induced antibody-dependent cell-mediated cytotoxicity (ADCC)

Cellular mechanisms of trastuzumab resistance include alteration(s) in cell signaling pathways (PTEN loss, activation of PI3K/Akt signaling), steric hindrance of antibody binding (by Muc-1/Muc-3), over-activation of alternate receptor kinases (HER3/c-Met/IGF-1R), and proteolysis of HER2 extracellular domain harboring target epitopes for antibody-based therapeutics. Prior studies of trastuzumab resistance have focused largely on cells selected ex vivo with the antibody in absence of human immune effector cells. We developed a selection model, wherein human HER2 positive BC cells (BT474, SKBR3) were subjected to acute ADCC (>90% cell death), trastuzumab concentration 100ug/mL, effector-target ratio 100:1, using human peripheral blood mononuclear cells (PBMCs) as effectors. Surviving cells were allowed to recover to confluence over 8-10 weeks, for 10 total rounds of ADCC selection ex vivo. Mock-treated parent, IgG1 isotype control, trastuzumab, and PBMCs alone were used as controls. ADCC assays based on calcein fluorescent labeling of live target cells, revealed significant reduction (maximum 20%, p<0.005) in cell lysis in immune-selected BT474 cell lines compared to parental controls (immune-selected SKBR3 cells exhibited a non-significant trend towards reduced ADCC). Transcriptome-wide next-generation RNA sequencing (Illumina NextSeq 500, 2 x 75 bp paired-end, median of 46 million paired-end reads/sample), coupled with pathway enrichment analysis (Reactome), followed by q-PCR validation, confirmed significant changes in expression in immune-selected cells (compared to parent control) for genes including: ALDH1, ANK1, TMPRSS3, HINT1, DNM2, TNNC1, COL4A4 in BT474; and ALDH1, ANK1, CAMP1, CPE, IDO1 in SKBR3 cells. Whole-genome sequencing (Illumina HiSeq X, 150 bp paired end, 30x coverage) elucidated 180 genes with single nucleotide variations (SNVs) in immune-selected cells compared to parent in BT474 cells, and 215 genes in SKBR3 cells. Thirty-four SNVs were shared in both cell lines. Further screening and validation confirm genes with SNVs demonstrating significant transcript up-regulation. These include: COL4A3, LEP, SOX-9 in BT474; and HLA-B, TNFRSF10B, HLA-B, PSMA6 in SKBR3. In further phenotypic analysis, ADCC-conditioned BT474 cells exhibit an elongated fibroblast-like morphology with multiple processes, in contrast to control. Immune-selected SKBR3 cells (and not BT474 cells) demonstrate significantly increased motility compared to control in transwell migration assays (p<0.001), and demonstrated increased cell proliferation (MTT assay, 10-15%, 48h; p=0.0242) as compared to parent controls. Our data indicate immune-selection by effector cells contributes to ADCC tolerance in vitro, and is associated with distinct genotypic and phenotypic alterations. Future investigation will determine whether Fc-engineered MAbs (afucosylated), antibody drug conjugates (T-DM1), or potentiation of ADCC by co-stimulatory agonist CD137 antibodies will re-sensitize ADCC-tolerance. This investigation will help to elucidate potentially targetable pathways that emerge from immune-selection with trastuzumab.

Citation Format: Biswas T, Fritzemeier R, Mark A, Meißner T, Young B, Jones BL, Pegram M. Characterization of HER2-positive breast cancer (BC) cells selected for tolerance to trastuzumab-induced antibody-dependent cell-mediated cytotoxicity (ADCC) [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 P3-03-06.

Abstract P4-14-01: Trastuzumab emtansine improves overall survival versus capecitabine plus lapatinib in patients with previously treated HER2-positive advanced breast cancer: Final results from the phase 3 EMILIA study

Introduction

T-DM1 is indicated for the treatment of advanced HER2-positive MBC in patients who previously received trastuzumab and a taxane (separately or in combination) based on data from the phase 3 EMILIA study (BO21977/TDM4370g; NCT00829166). In the primary PFS and second interim OS analyses, respectively, T-DM1 significantly improved PFS (median 9.6 vs 6.4 months; HR=0.65; 95% CI, 0.55–0.77; p<0.0001) and OS (median 30.9 vs 25.1 months; HR=0.68; 95% CI, 0.55–0.85; p<0.0006) compared with capecitabine (X) plus lapatinib (L). T-DM1 treatment was associated with fewer grade ≥3 AEs (41% vs 57%) vs XL. Here we present the final OS analysis from EMILIA.

Methods

EMILIA was a randomized, open-label study of patients with centrally confirmed HER2-positive (IHC3+ and/or FISH amplification ratio ≥2.0), unresectable, locally advanced or MBC, previously treated with trastuzumab and a taxane. Patients were randomized 1:1 to T-DM1 (3.6 mg/kg IV every 3 weeks) or X (1000 mg/m2 PO twice daily, days 1–14 every 3 weeks) plus L (1250 mg PO daily). The final OS analysis was to be conducted following 632 events, and these results are descriptive only. Since the OS efficacy boundary (HR<0.71, p=0.0025) was crossed in the second interim analysis, a protocol amendment allowed crossover from XL to T-DM1.

Results

From Feb 2009 to Oct 2011, 991 patients were randomized to T-DM1 (n=495) or XL (n=496). Patient disposition by the data cutoff (31 Dec 2014) is shown in Table 1. OS was longer with T-DM1 vs XL (median OS 29.9 vs 25.9 months; HR=0.75; 95% CI, 0.64–0.88; p=0.0003). In a sensitivity analysis, which censored crossover patients at the time of switching from XL to T-DM1, the HR was 0.69 (95% CI, 0.59–0.82; p<0.0001). The overall safety profile was similar to previous analyses (Table 2). More grade ≥3 thrombocytopenia occurred with T-DM1 vs XL (14.3% vs 0.4%). Cardiac dysfunction occurred in 2.7% of T-DM1 patients vs 3.5% of XL patients.

Table 1. Patient disposition. T-DM1 (n=495)XL (n=496)Median treatment duration, months7.6X: 5.3  L: 5.5Median duration of follow-up, months47.841.9Discontinued study, n (%)364 (74)404 (82)Crossover, n (%)  Per protocolaNot applicable136 (27)Non-protocol therapybX: 252 (54)X: 53 (11) L: 224 (48)L: 74 (15)aMedian duration of follow-up among per-protocol crossover patients was 24.1 months.bBy investigator choice after study treatment discontinuation; X or L could be given in combination with each other or other agents after progression.

Table 2. Safety summary in patients who received ≥1 dose of study treatment.n (%)T-DM1 (n=490)XL (n=488)Grade ≥3 AEs233 (47.6)291 (59.6)Serious AEs91 (18.6)99 (20.3)AEs leading to dose reduction91 (18.6)X: 205 (42.0)  L: 98 (20.1)

Conclusions

This final analysis of EMILIA shows an OS benefit of T-DM1 compared with XL. While median drug exposure was longer with T-DM1 than XL, T-DM1 was associated with fewer grade ≥3 AEs and AEs leading to dose reduction compared with XL. These final OS results confirm that T-DM1 treatment improved survival, even in the presence of treatment crossover, and reaffirm T-DM1 as the standard of care in patients with previously treated HER2-positive MBC.

Citation Format: Diéras V, Miles D, Verma S, Pegram M, Welslau M, Baselga J, Krop I, Blackwell K, Kang B, Xu J, Green M, Gianni L. Trastuzumab emtansine improves overall survival versus capecitabine plus lapatinib in patients with previously treated HER2-positive advanced breast cancer: Final results from the phase 3 EMILIA study. [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 P4-14-01.

Abstract P4-12-09: Results from a phase 2a study of trastuzumab emtansine, paclitaxel, and pertuzumab in patients with HER2-positive metastatic breast cancer

Introduction

The antibody-drug conjugate trastuzumab emtansine (T-DM1) combines the antitumor properties of trastuzumab (H) with the cytotoxic agent DM1 via a stable linker. T-DM1 prolonged PFS and OS vs standard therapy in a phase 3 study of patients (pts) with HER2-positive metastatic breast cancer (MBC) previously treated with H and a taxane. Preclinical data suggest synergy when T-DM1 is combined with paclitaxel (T) or pertuzumab (P). In the phase 1b study TDM4652g, the maximum tolerated doses of T-DM1 + T ± P were defined. Here we present results from the phase 2a expansion, which further explored feasibility and safety.

Methods

TDM4652g is a phase 1b/2a open-label study of pts with HER2-positive locally advanced or MBC. Pts had no prior T-DM1 or P, no baseline peripheral neuropathy (PN; phase 2a only), and had LVEF ≥50%. Pts in phase 2a were randomized to T-DM1 3.6 mg/kg q3w + T 80 mg/m2 qw ± P 840 mg loading dose [LD], then 420 mg q3w. The primary objective, feasibility, was assessed by the percent of evaluable pts receiving ≥12 doses of T within 15 weeks of cycle 1, day 1, and those receiving 12 consecutive weeks of T.

Results

Forty-four pts were enrolled (T-DM1 + T, n = 22; T-DM1 + T + P, n = 22); the data snapshot date was May 23, 2013. Median age was 52.5 years (range, 35–81); median number of prior agents for MBC was 6 (range, 0–12). 43 (98%) pts had previously received H, and 36 (82%) pts had received taxane therapy. Median dose intensities were T-DM1, 94% (range 54–105); T, 50% (range 9–100) and P, 100% (range 67–100). 2 pts were not evaluable for feasibility (progressive disease [PD] before receiving 12 doses of T). 21/42 (50%) pts received ≥12 doses of T within 15 weeks; 6/42 (14%) pts received 12 consecutive doses by week 12, and 33/42 (79%) pts received ≥8 doses within 12 weeks. Grade 3/4 adverse events (AEs) were reported for 18 (82%) and 17 (77%) pts in the T-DM1 + T and T-DM1 + T + P groups, respectively (see Table for AEs and best responses). Ten pts discontinued early due to PD (n = 6), PD-related death (n = 2), AEs (n = 1), or withdrawal from the study (n = 1). 21 pts discontinued T due to AEs, most commonly PN (n = 12).

Grade 3/4 AEs occurring in >1 patientAE, n (%)All patients (N = 44)TDM1 3.6 mg/kg q3w + T 80 mg/m2 qw (n = 22)TDM1 3.6 mg/kg q3w + T 80 mg/m2 qw + P 840 mg LD, 420 mg q3w (n = 22)Neutropenia10 (23)6 (27)4 (18)Peripheral neuropathy9 (20)3 (14)6 (27)Fatigue6 (14)3 (14)3 (14)Thrombocytopenia6 (14)5 (23)1 (5)Anemia3 (7)2 (9)1 (5)Abdominal pain2 (5)2 (9)0Decreased hemoglobin2 (5)1 (5)1 (5)Muscosal inflammation2 (5)1 (5)1 (5)Muscular weakness2 (5)02 (9)Nausea2 (5)1 (5)1 (5)Best response,* n (%)CR2 (5)1 (5)1 (5)CR confirmed1 (2)1 (5)0PR27 (61)13 (59)14 (64)PR confirmed8 (18)3 (14)5 (23)SD10 (23)6 (27)4 (18)PD3 (7)1 (5)2 (9)*At any time point with responses ordered CR>PR>SD>PD.

Conclusions

Overall, 50% of pts received ≥12 doses of T within 15 weeks. Adding P to the combination of T-DM1 + T did not appear to increase the incidence of grade 3/4 AEs. Data support further investigation of T-DM1 + T ± P in larger studies in early breast cancer. Final data from all phase 2a patients will be available for the full report.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-12-09.

Thalidomide and chemotherapy combination

Angiogenesis has been shown to be important in tumor growth and metastasis. Thalidomide, an oral sedative, has recently been found to inhibit angiogenesis. We therefore set out to ask whether thalidomide can be used as therapy for breast cancer. In a mouse model of breast cancer, we found that thalidomide alone did not suppress tumor growth. However, mice treated with thalidomide in combination with cytoxan and adriamycin had significantly smaller tumors than those given the two chemotherapeutic agents alone (3,432 +/- 303 mm(3) versus 4,643 +/- 203 mm(3), p = 0.0005). We proceeded to administer thalidomide together with chemotherapy to seven breast cancer patients in the context of a Phase I trial. Side effects attributed to thalidomide were minimal, and included constipation and a rash. We concluded that an approach at cancer therapeutics combining an antiangiogenic agent such as thalidomide with conventional chemotherapy may be feasible and deserves further studies.

P1-07-02: Discordance between Central and Local Laboratory HER2 Testing from a Large HER2−Negative Population in VIRGO, a Metastatic Breast Cancer Registry

Background: HER2 overexpression is associated with unfavorable prognosis and is reported in 18–25% of breast cancers (BC). HER2 testing is often performed using immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH). Because of the significant benefit of HER2−directed therapies, it is critical to accurately identify women whose tumors are HER2+. Reports have noted discordance between HER2+ test results from local vs. large reference labs in patients with HER2+ BC evaluated for trastuzumab-based clinical studies. There are little published data on central testing of BC found to be negative locally.

Patients and Methods: VIRGO is an observational cohort of N=1,287 women with primarily HER2−negative metastatic BC. An optional tissue collection substudy was conducted, and 776 patient samples were received and centrally retested. Central testing was performed at 2 reference labs and tumors were deemed HER2+ if IHC 3+ and/or FISH positive (HER2:CEP17 ratio ≥2.0). Tumors with unknown/missing local HER2 status (n=68) were excluded from primary analyses. Number of patients potentially affected based on BC incidences from the American Cancer Society (ACS) 2011 estimates and the World Health Organization (WHO) 2008 report were calculated. Testing on the remainder of the HER2−negative cohort is in process.

Results: Central retesting has been performed on tumor samples from n=373 patients to date: HER2−negative locally evaluable tumors (n=301), n=4 HER2−negative locally with no evaluable tumor, and HER2 unknown (n=68). A total of 301 unique patient samples were included in the primary analysis. Of these, 15 (4.98% [95% CI (2.7%, 7.9%)] were found to be HER2+ by central testing (Table). Based on sensitivity analyses assuming all 68 tumors with unknown HER2 status to be negative locally, 4.07%(15 /369) would be centrally HER2+.

Abstract B39: Results of a pilot study: Identification of ethnicspecific gene expression differences in normal breast tissue

Disparities in breast cancer stage of presentation and survival rates exist in patients of different ethnicities. These differences are undoubtedly a result of a combination of factors, including socio-economic, lifestyle, tumor characteristics and inherent factors, such as genetic composition. Our group remains focused on analyzing genetic/genomic contributions to these disparities, with the ultimate goal of increased biological understanding, leading ultimately to individualized, ethnic-specific diagnostic and therapeutic approaches. We have previously reported ethnicspecific expression patterns in matched tumor and adjacent samples from a cohort of triple negative breast cancer (BC) samples. Here we report results from a parallel study focusing on gene expression profiling in a multi-ethnic collection of normal breast tissues. Study samples were cut from FFPE (formalin fixed paraffin-embedded tissue) blocks saved from local reduction mammoplasty cases [5 Caucasians (CAU); 7 African-American (AA); and 4 Hispanics (HIS) women with no personal or family BC history]. These were sent to Almac Diagnostics for RNA isolation, cDNA preparation, and hybridization of cDNAs to a cancer focused gene expression array (Xcel) containing 110,961 probes, representing 19,905 unique known genes. Arrays were quantile normalized and log transformed to the median of all samples. The probes were filtered to remove variation within each ethnic group to ≤ 0.5 SD, while the variation between the three groups was maintained at ≥ 0.2 SD. Samples which had < 90 % similarity based on ‘Pearson correlation’ were removed from subsequent analyses. This removed three AA, 2 CAU and 1 HIS samples. Finally, the filtered subset of 68,145 probes common to the three ethnic groups was then compared on GeneSpring® analytical software. A mean centered Principal Component Analysis (PCA) was performed on the filtered subset of normalized data. In addition, a one way ANOVA between the three ethnic groups identified 1884 significantly differentially expressed probes representing 237 unknown and 1647 known genes (P ≤ 0.05; Benjamin-Hochberg multiple testing corrected). Post-hoc analysis of the 1884 significant probes identified 207 probes significantly differentially expressed between CAU and AA; 1863 probes were found to be differentially expressed between HIS and CAU, and 1873 probes were significantly differentially expressed between HIS and AA. These results suggests that the HIS group/samples have a unique gene signature in comparison to the other ethnic groups analyzed. When the differentially expressed gene list across ethnicities is reduced to those genes with 1.5 fold change, the number of statistically-significant differentially-expressed genes across ethnicities decreases dramatically (7 AA vs. Cau; approx 600 AA vs HIS; 600 CAU vs His), suggesting a much more select group of differentially-expressed genes in normal breast tissue across these ethnic groups. Since the overall sample size is small, we are continuing to validate these data on a larger set of samples. In addition, we are performing laser capture micro-disssection of these samples, to compare gene expression patterns in stroma vs. epithelial. We will present our latest study results, including pathway analysis of statistically-significant differentially-expressed genes across the three ethnic groups.

Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):B39.

Abstract P5-06-03: Truncated ERBB2 Receptors: Diagnostic and Therapeutic Targets

Background:

Patients with ERBB2+ breast cancer have aggressive disease and poor prognoses. It is now apparent that many ERBB2+ tumors also express truncated ERBB2 receptors (t-ERBB2s), namely p110 and p95. Increased expression of t-ERBB2s by breast tumors correlates with increased nodal involvement, distant metastasis, and poor clinical outcome in patients. Because t-ERBB2s lack the epitope bound by trastuzumab, expression of high levels of these isoforms may designate patients who would be better treated with alternative anti-ERBB2 therapy such as lapatinib; unfortunately, there is currently no clinical method to distinguish full-length p185- versus t-ERBB2 in patient tumor samples. Materials and Methods:

Recombinant forms of p185-, p110- and p95-ERBB2 were constructed using standard cloning techniques and expressed in human mammary epithelial cells (HMLE) via retroviral vector. The expression and subcellular localization of constructs were confirmed by western blot analysis and confocal microscopy. The ability of p185- and t-ERBB2 constructs to transform HMLE cells was evaluated using soft agar assays, and the effects on migration and invasion of these cells were investigated by transwell assays. Finally, the in vivo tumor formation by p185- vs. t-ERBB2 expressing cells was evaluated in immunodeficient mice. Additionally, a novel proximity-based antibody-capture method method to discern full-length versus t-ERBB2 in patient tumor samples was assessed (COPIA). Block tumors and fine-needle aspirates from patient tumor samples were used for quantifying total and phosphorylated ERBB2 receptors.

Results and Discussion:

Recombinant p185- and t-ERBB2 constructs were stably expressed in HMLE cells, and were correctly targeted to the cell membrane, as shown by confocal immunofluorescence microscopy and immunoblot. Expression of p110 t-ERBB2 increased migration and invasion of HMLE cells compared to p185 ERBB2 (P<0.0001), while p110, p95m and p185 ERBB2s were equally effective at enhancing anchorage-independent growth. In vivo, expression of p110 t-ERBB2 but not other isoforms led to increased tumor formation in mice compared to controls (P<0.005). No apparent phenotypes were elicited by expression of intracellular t-ERBB2 isoforms. Using COPIA testing, t-ERBB2 isoforms were detected in strongly ERBB2- positive tumors (16 of 31 samples, 52%) and were phosphorylated in 10 of 31 (32%). As expected, t-ERBB2s were not detected in ERBB2-negative tumor samples.

Truncated ERBB2s, particularly p110, may be major pathogenic drivers in ERBB2+ cancers. These isoforms may accelerate disease progression by promoting invasion and metastasis, and likely mediate resistance to trastuzumab and other therapies. Thus, t-ERBB2s represent attractive novel targets for diagnosis and treatment of ERBB2+ breast cancers.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-06-03.

Abstract P5-05-02: Whole Genome In Vivo RNA Interference Screening Identifies the Leukemia Inhibitory Factor Receptor as a Novel Breast Tumor Suppressor

Background: Cancer is caused by mutations in oncogenes and tumor suppressor genes resulting in the deregulation of processes fundamental to the normal behavior of cells. The identification and characterization of oncogenes and tumor suppressors has led to new treatment strategies that have significantly improved cancer outcome. The advent of next generation sequencing has allowed the elucidation of the fine structure of cancer genomes, however, the identification of pathogenic changes is complicated by the inherent genomic instability of cancer cells. Therefore, functional approaches for the identification of novel genes involved in the initiation and development of tumors are critical. Methods: In order to identify functionally important tumor suppressor genes we have conducted the first human whole genome in vivo RNA interference (RNAi) screen. Partially transformed human mammary epithelial cells (HMLEs), which do not form tumors in immunodeficient mice, were infected with the Expression Arrest™ GIPZ lentiviral shRNA library consisting of 62,000 shRNAs targeting the whole human genome, and injected into the mammary fat pad of immunodeficient mice. shRNAs that silenced tumor suppressor genes fully transformed the mammary epithelial cells resulting in tumor formation. Candidate tumor suppressor genes were identified by PCR amplification and sequencing of tumor integrated shRNAs. For validation, candidate tumor suppressor genes were silenced in HMLEs and ectopically expressed in fully transformed breast cancer cells. The effect of modifying gene expression on the transformed phenotype was assessed using soft agar colony formation assays. Clinical significance was determined by comparing expression in normal and cancerous human breast tissue using Oncomine Research. Results and Discussion: Using our novel approach, we identify previously validated tumor suppressor genes including TP53 and MNT, as well as several novel candidate tumor suppressor genes including leukemia inhibitory factor receptor (LIFR). Silencing LIFR expression with multiple shRNA constructs fully transformed human mammary epithelial cells resulting in enhanced colony formation in soft agar (P<0.05). Furthermore, overexpression of LIFR significantly inhibited colony formation in soft agar of fully transformed MDA231 and MCF7 breast cancer cells (P<0.01). In addition, our analysis of clinical data revealed that LIFR expression is significantly decreased in a large percentage of human cancers including breast (P<0.0001), lung (P<0.0001), hepatocellular (P<0.0001) and gastrointestinal tumors (P<0.0001). These results validate LIFR as a previously unidentified highly significant tumor suppressor, and also demonstrate the power of whole genome in vivo RNAi screens as a method for identifying novel genes regulating tumorigenesis.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-05-02.

Abstract P1-11-05: Phase 2 Study of Neoadjuvant Treatment with Cellular Redox Modulator NOV-002 in Combination with Doxorubicin and Cyclophosphamide Followed by Docetaxel (AC→T) in Patients with Stage II-III HER-2 (-) Breast Cancer

Background: NOV-002 (a formulation of disodium glutathione disulfide) modulates signaling pathways involved in tumor cell proliferation and metastasis and enhances anti-tumor immune responsiveness in tumor models. The addition of NOV-002 to a range of cytotoxic chemotherapeutic regimens has been shown to increase their anti-tumor efficacy in several early phase oncology trials and in animal models. Pathological complete response (pCR) has been demonstrated to be associated with favorable overall survival in primary breast cancer, and neoadjuvant treatment of early breast cancer aims at achieving high rates of pCR. In patients with HER-2 (-) breast cancer pCR rates with anthracycline and taxane combinations have been reported to be approximately 10-20% depending on hormone receptor status. We conducted a clinical trial in HER-2 negative patients (pts) combining daily N0V-002 with AC→T. Methods: Women with newly diagnosed stages II-III HER-2 (-) breast cancer received AC x 4 [60/600 mg/m2] followed by T [100 mg/m2] x 4 every 3 weeks in conjunction with daily N0V-002 [60mg IV day 1 and subcutaneously days 2-21 of each cycle]. The primary endpoint is pCR, defined as: (i) ypN0, and (ii) ypT0 or presence of invasive tumor <10mm.

Sample size (n=46 total patients) was calculated using a Simon 2-stage optimal design assuming a doubling of the historical pCR rate with the addition of NOV-002 to AC→T from a p0 of 0.16 to a p1 of 0.32. If a total of 12 or more patients experience a pCR by the end of the trial, then the treatment regimen will be declared active. The calculation assumes an alpha of 0.05 and 80% power.

Results: A total of 39 pts have been enrolled to date across three study sites, with 31 patients having completed chemotherapy and undergone surgery. One patient dropped out during cycle 1 and was not assessable for response; 5 are currently receiving chemotherapy; and 2 patients have completed all chemotherapy, but have not yet undergone surgery. A total of 292 chemotherapy cycles have been administered, with 92% of all patients being able to complete all 8 cycles of planned chemotherapy. Of the 31 evaluable patients, 12 achieved a pCR (39%), meeting the primary endpoint of the trial. In patients with residual invasive primary breast tumor <10mm and ypN0 (19%) mean residual tumor size was 4.4 mm. Interestingly, of the 17 patients with biopsy-proven axillary involvement, 4 (23%) had no residual invasive tumor in axillary nodes at time of surgery. In 26 patients with estrogen positive breast cancer, which is least sensitive to chemotherapy, 42% achieved a pCR. The most common toxicities included: nausea, sensory neuropathy, emesis, fatigue, and hand-foot syndrome. Conclusions: The addition of NOV-002 has to date resulted in a doubling of previously published pCR rates with AC→T in HER-2 (-) breast cancer patients. Subsequent investigation of NOV-002 in conjunction with neoadjuvant chemotherapy in breast cancer is warranted. Updated clinical data on all 39 patients as well as immunologic correlative markers will be presented.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-11-05.

Abstract P4-01-05: Lapatinib Resistance Confers Cross-Resistance to Microtubule Inhibitors in ErbB2-Overexpressing Breast Cancer Cells

ErbB2 gene amplification occurs in approximately 20% of all breast cancers and is associated with an aggressive subtype with poor clinical prognosis. Acquired resistance to erbB2-targeted therapies is a common occurance even in patients who show an initial clinical response to trastuzumab or lapatinib-based regimens. Optimal treatment for relapsed disease following erbB2 targeted therapies has not been defined. Therefore, we sought to evaluate whether cytotoxic agents have cross-resistance to lapatinib in cell lines that have acquired resistance to lapatinib. Here we established a model of acquired lapatinib resistance derived from erbB2 overexpressing breast cancer cell lines, BT474 and SKBR3. Lapatinib resistant cell lines, BTLapR and SKLapR, were generated by growth in the continuous presence of 2.6 uM lapatinib (peak plasma concentration in human subjects) resulting in IC50 of 4.72 uM (BTLapR) and 0.083 uM (BT474) (P<0.0001). IC50 of SKLapR and SKBR3 were 17.72 uM and 0.1637 uM (P<0.0001), respectively. Next, resulting cells were treated with different classes of chemotherapeutics (2 taxanes, 2 vinca-alkaloids, 1 epothilone, 1 anthracycline, 1 antimetabolite, 2 platinums, and 1 alkylating agent) in order to address cross-resistance to lapatinib. BT474 and BTLapR as well as SKBR3 and SKLapR were exposed to each chemotherapeutic agent and cell viability was evaluated at 72h using a cell proliferation assay (AlamarBlue®). We found that BTLapR was significantly cross-resistant to 5 microtubule inhibitors (paclitaxel, docetaxel, vinorelbine, vinblastine, and ixabepilone), but SKLapR was not (shown in table below).

IC 50 of Significant Drugs on Lapatinib Resistant BT474 cells

Previous studies have shown that resistance to lapatinib can switch cell survival signaling from the erbB2 to ER pathway, and that ER signaling can stimulate beta III tubulin expression. We therefore hypothesize the differential responses to microtubule inhibitors in BTLapR and SKLapR might be explained by the fact that BT474 has both estrogen (ER) and progesterone receptor (PR), but SKBR3 express neither. Moreover, beta-III tubulin is known to be a key resistance mechanism of microtubule inhibition. Western blot analysis of baseline protein expression in both acquired lapatinib-resistant and parental cells indicates that ER signaling is involved in stimulating beta III tubulin and is linked to the development of resistance to microtubule inhibitors. These findings point to a potential mechanism to address cross resistance between lapatinib and microtubule-interacting agents, which could have potential clinical implications when considering salvage therapies following lapatinib treatment.

Abstract P2-19-03: Src Kinase Inhibition with AZD0530 Plus Anastrozole in Postmenopausal Hormone Receptor Positive (HR+) Metastatic Breast Cancer (MBC)

Background: p27 is a negative regulator of cell cycle that is frequently decreased in primary human breast cancer (BC) due to accelerated proteolysis. In HR+ BC, p27 function is required to promote G1 arrest following anti-estrogen treatment. cSrc is overexpressed/activated in up to 70% of BC. Src kinase phosphorylates p27 reducing its inhibitory function toward cyclin E-Cdk2, thereby facilitating p27 degradation. AZD0530 is a potent, orally available dual inhibitor of Abl and Src family kinases. Preclinical data indicate AZD0530 cooperates with anastrozole to inhibit BC cell growth in vitro and in vivo (Chen, et al., Clin Cancer Res 2009). We hypothesized that Src inhibition would augment p27 to promote antiproliferative effects of anastrozole in HR+ BC. Methods: This is an NCI funded investigator-initiated, open label phase IB clinical trial conducted under an investigator IND. Target population: postmenopausal HR+ relapsed or MBC who are candidates for aromatase inhibitor therapy. Key Inclusion: postmenopausal females, age ≥18, advanced or locally relapsed unresectable HR+ measurable/evaluable (RECIST) disease, ECOG 0-2, informed consent. Cohorts of 3 patients were initiated with AZD0530 175mg PO/day in combination with anastrozole 1mg PO daily in a planned dose de-escalation study design with subsequent cohort expansion to 12 subjects for PK assessment (both AZD0530 and anastrozole) performed at 6, 12, 24, 48, and 72 hours, 8, 15 and 22 days.

Results: Among 12 patients enrolled, AZD0530 plus anastrozole was well tolerated (no dose limiting toxicities) without need for dose de-escalation. Drug related adverse events: grade 3 lymphopenia (N=3), neutropenia (N=2), anemia (N=1) and reversible grade 1/2 transaminase elevation (N=9). Serious adverse events were observed in 2 patients (urosepsis and CNS hemorrhage due to CNS metastasis), neither considered drug-related. Interstitial pneumonitis was not observed. PK assessment: mean day 21 serum concentration = 298±38.4 ng/ml for AZD0530 and 51±5.6 ng/ml for anastrozole, indicating no evidence for drug-drug interaction between the 2 agents. Clinical efficacy: There were no RECIST clinical responses in this heavily pretreated population. However, notably patients with bone metastasis reported improvement in bone pain, and 2 patients had prolonged disease stability (>7 and 10 months with improvement of PET and bone scans) despite prior hormone refractory disease. Conclusions: Src kinase inhibition with AZD0530 combined with anastrozole was well tolerated without significant PK interaction. The recommended phase II dose is AZD0530 175mg PO plus anastrozole 1mg PO daily. A randomized phase II study of this combination is currently underway in the neoadjuvant setting including complete PK/PD assessment and molecular correlative studies to evaluate predictors of response. Supported by NIH 1R21CA133884-01A1

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-19-03.

Abstract P4-08-12: Gene Expression Profiling of Formalin-Fixed, Paraffin-Embedded (FFPE) Breast Cancer Samples and Analysis of Intrinsic Subtypes

Background: The advent of microarray technology has enabled robust, high throughput analysis of breast cancer (BC) transcriptomes. Indeed, molecular classification of BC has been revolutionized by the advent of Gene Expression Profiling (GEP). FFPE tumor samples have presented a technical challenge for GEP studies due to degradation of extracted RNA. Newer technologies have overcome this challenge, and have lead to generation of quality GEP data and thus, new insights using archived tissues. Of particular interest to our group has been application of these techniques to the study of triple negative breast cancer (TNBC). TNBC is a BC sub-type characterized by a lack of erbB2 gene amplification and estrogen and progesterone receptor expression. This clinically-defined BC sub-type carries a poor prognosis, is insensitive to hormonal or HER-2 targeted therapies, and displays different incidences among ethnic groups. A better understanding of the genetic and molecular mechanisms underlying TNBC is critical to improving clinic outcomes and developing tailorized therapies.

Study Objective: We demonstrate utility of FFPE BC samples in obtaining consistent, reproducible GEP data, and apply this technology to validate the ability to identify intrinsic BC subtypes in unselected specimens, as well to identify differentially expressed genes in TNBC.

Methods: RNA isolation and labelled cDNA preparation were performed from freshly cut FFPE sections. Samples were hybridized to a breast cancer focused gene expression array (Breast Cancer DSA Research Tool, Almac Diagnostics Inc). DSA chip quality was assessed on parameters selected automatically from GCOS report files per chip using MATLAB script based web application developed by Almac. Data pre-processing used the Resolver Error Model. All parameters including Raw Q, Background, Scaling Factor and all controls met quality criteria set by Affymetrix and Almac Dx SOPs. Hybridization results were assessed with Principal Component Analysis and Cluster Analysis in a Rosetta Resolver Gene Expression Data Analysis System to identify potential outliers, contamination, or intra-tumor heterogeneity. In total, 47 FFPE breast cancer samples covering a range of hormonal receptor status and sub-types were profiled, as were 28 TNBC FFPE tumor samples.

Results: Cluster analysis demonstrated that the Almac Breast Cancer DSA was able to clearly separate the 47 tumor samples of the mixed subtype group into the previously described intrinsic subgroups. Moreover, the DSA array contains 167 probesets which correspond to the 40 of the PAM-50 gene set used as a subtype predictor (Parker et al 2009). Analysis of the TNBC samples using the 167 probeset (based on mean intensity for probes representing each of the 40 genes) showed 100% consistency with published results demonstrating a basal-like gene expression signature. Summary: We have shown that our study methodology used can reliably measure gene expression in FFPE BC samples, and that the Breast Cancer DSA can be used to evaluate intrinsic subtypes of BC specimens. Analysis of the TNBC cases showed complete concordance between the PAM-50 gene set and the corresponding genes in the DSA. These study results are being validated in a larger data set.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-08-12.

Gene Expression Profiling of Formalin-Fixed, Pariffin-Embedded (FFPE) Tissues from Triple-Negative (TN) Breast Cancer (BC) Patients

Background: FFPE tumor samples present a technical challenge for gene expression profiling studies. Newer technologies are resulting in quality data and new insights from these archived tissues. TNBC is a sub-type of BC characterized by a lack of erbB2 gene amplification and estrogen and progesterone receptor expression. This clinically-defined BC sub-type carries a poor prognosis, is insensitive to hormonal or HER-2 targeted therapeutic agents, and has different incidence among ethnic groups. A better understanding of the genetic and molecular mechanisms underlying TNBC is critical to improving clinic outcomes and developing individualized therapies.Study Objective: We demonstrate the utility of FFPE samples in obtaining consistent, reproducible data from gene expression arrays, and apply this technology to the identification of differentially expressed genes between TNBC and normal breast tissue that are common or unique among selected ethnic groups.Methods: RNA isolation and labeled cDNA preparation from freshly cut FFPE blocks (marked by a pathologist as to normal vs. tumor tissue) was performed using the NuGEN™ WT-Ovation™ FFPE RNA Amplification System. Hybridization of tumor and normal cDNAs occurred to a breast cancer focused gene expression array (Breast Cancer DSA Research Tool, Almac Diagnostics Inc). Each patient' sample served as it's own control (tumor vs. normal). In total, 75 FFPE samples were profiled. The quality of each DSA chip was assessed on parameters selected automatically from GCOS report files per chip using MATLAB script based web application developed by Almac Dx. Data pre-processing used the Resolver Error Model. All parameters including Raw Q, Background, Scaling Factor and all controls met quality criteria set by Affymetrix and Almac Dx SOPs. Hybridization results were assessed using Principal Component Analysis and Clustering Analysis in Rosetta Resolver Gene Expression Data Analysis System 7.1 to identify potential outliers, contamination, or intra-tumor heterogeneity.Results: A Sign Agreement Matrix of FFPE and fresh frozen tissue samples during validation of the Breast Cancer DSA demonstrated that 98% of the probesets showed the same direction of fold change [p Spearman(FC)=0.84]. The FFPE samples had an average present call ∼ 43%, and more than 90% of the FFPE samples had present call rates greater than 25%. QC analysis demonstrated that the Almac Breast Cancer DSA was able to clearly and consistently separate tumor samples from normal in FFPE tissues and to identify samples of quality or integrity issues. Application of this methodology to analyses of differentially expressed transcripts between cancer and normal tissue samples across ethnicities in the TNBC samples, detected 1350 differentially expressed genes in the African-American group, 1220 genes in the Caucasian group and 1226 genes in the White Hispanic group. We also observed certain subtle ethnic-specific expression patterns across these three ethnic groups.Summary: The above-described methodology can be used to reliably measure gene expression in FFPE breast samples. Our study results are being validated in a larger data set.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6125.

Truncated p95erbB2 Isoforms Are Capable of Transforming Human Mammary Epithelial Cells

Background:Objective clinical response to trastuzumab monotherapy in erbB2-amplified first line metastatic breast cancer is 34% (Vogel, et al., JCO 20: 719-26, 2002). Amongst patients who respond, most develop resistance (defined by disease progression on trastuzumab). One proposed mechanism of trastuzumab resistance is proteolytic cleavage of erbB2 receptor from its full-length (p185) form into truncated, constitutively active p95. Increased expression of p95erbB2 correlates with increased nodal involvement and poor clinical outcome. Because p95erbB2 lacks the trastuzumab binding epitope, expression may designate patients who would be suitable for treatment with erbB2 kinase inhibitors.Materials and Methods:Recombinant p185erbB2 and p95erbB2 constructs were stably expressed in several cell types via retroviral vector. Additionally, an intracellular form of p95erbB2 that arises via alternative translation and an intracellular p95erbB2 construct containing two copies of a nuclear localization sequence were also expressed. Expression and proper subcellular localization of constructs were confirmed by cell fractionation, western blot analysis and confocal microscopy. Transformation of human mammary epithelial (HMEC) and NIH3T3 cells by p185erbB2 and p95erbB2 isoforms was evaluated by anchorage independent growth using a quantitative fluorescent soft agar assay, and effects on migration and invasion of these cells were investigated by wound-healing and transwell assays. Cells transfected with oncogenic Ras or empty vector were used as positive and negative controls in these experiments.Results and Discussion:Recombinant p185erbB2 and p95erbB2 constructs were stably expressed in HMEC and NIH3T3 cells, and were correctly directed to the cell membrane; nuclear targeted intracellular p95erbB2 was correctly localized to the cell nucleus. Both p185 erbB2 and membrane-bound truncated p95erbB2 were sufficient to transform HMEC cells as compared to empty vector control transfected cells [mean fluorescence intensity empty vector control 2480 ± 464 (1 standard deviation); mean fluorescence intensity p185erbB2 9208 ± 2528, p= 0.0106; mean fluorescence intensity p95erbB2 6615 ± 1588, p= 0.0124)] as was the positive control oncogenic Ras (mean fluorescence intensity 4350 ± 433, p=0.0069). Interestingly, nuclear-targeted p95erbB2 was also sufficient to transform HMEC cells (mean fluorescence intensity 6492 ± 818, p=0.0018). These data support the hypothesis that truncated p95erbB2 species may be major pathogenic drivers in erbB2-amplified cancers. P95erbB2 therefore represents an attractive target for diagnosis and treatment of erbB2+ breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3136.

First-line lapatinib combined with letrozole versus letrozole alone for hormone receptor positive (HR+) metastatic breast cancer (MBC): Subgroup analyses of borderline FISH+, IHC 2+, HER2 unknown (UNK), and treatment-naive (TN) populations from EGF30008

1062

Background: This double-blind, placebo-controlled, phase III trial assessed the benefit of adding lapatinib, an oral EGFR/HER2 tyrosine-kinase inhibitor, to letrozole alone in patients (pts) with HR+ MBC. The previously reported primary endpoint, investigator (INV) assessed PFS in HER2+ tumors, showed a significant benefit from dual therapy. Median PFS in the HR+ HER2+ population increased from 3 months (mo) in the letrozole/placebo group to 8.2 mo in the letrozole/lapatinib group [Hazard Ratio (95% CI)=0.71 (0.53,0.96), stratified log rank p = 0.019]. The HER-2-ve population did not derive benefit from the combination. Benefit from combined treatment was evaluated in a number of pre-planned exploratory subsets, including a noted trend in the HER2-ve population who progressed within 6 mo of receiving prior tamoxifen. Methods: 1286 pts were randomized to letrozole/lapatinib or letrozole/placebo. HER2 positivity was defined by a positive FISH ratio or by immunohistochemistry (IHC) 3+ in a central laboratory. INV assessed PFS in the sub-populations were analyzed using Kaplan-Meier with stratified log rank to compare treatment arms. These included tumor samples that were FISH borderline1.8–2.2 (n = 52), IHC 2+ (n = 215), HER2 status UNK (n = 115), and neo/adjuvant TN (n = 656). Results: INV assessed PFS demonstrated no significant prolongation for dual therapy for any of the exploratory populations [Hazard Ratio: (95%CI), p-value]; FISH 1.8–2.2 [1.03 (0.55, 1.95), p = 0.918]; IHC 2+ [1.13 (0.82, 1.57), p = 0.441]; HER2 UNK [0.71 (0.45,1.11), p = 0.126]; TN [0.88 (0.73, 1.07), [p = 0.199]. Conclusions: The combination of letrozole and lapatinib did not significantly improve PFS in any of the pts with lower levels of HER2 expression (borderline FISH, IHC 2+, or HER2 UNK) or in TN pts. These data confirm the HER2-ve result previously reported and substantiate that only tumors with the target benefit from the addition of a targeted therapy.

[Table: see text]

Relevance of serum HER2 extracellular domain (sECD) in EGF30008, a study of letrozole ± lapatinib in patients (pts) with hormone-receptor positive (HR+) metastatic breast cancer (MBC)

1019

Background: Elevated baseline sECD (BsECD) correlates weakly with HER2 overexpression (HER2+). HR+ MBC. Lapatinib benefit was reported in pts with HER2+ tumors irrespective of BsECD status; BsECD status did not predict benefit for HER2- negative (HER2-ve) tumors. sECD levels and their predictive and prognostic value for progression-free survival (PFS) were further examined in a randomized, phase III trial of letrozole ± lapatinib. Methods: Pts (n=1286) with HR+ MBC were randomized to letrozole with placebo (P) or lapatinib (L). HER2 status was evaluated by FISH or IHC in archived tissue. sECD was measured by ELISA at baseline (n=1102 available samples), and every 4 wk. Pts were considered sECD+ if serum sECD was >15 ng/ml. Results: BsECD was positive in 14% (125/894) and 42% (87/208) of pts with HER2-ve and HER2+ tumors, respectively. Correlation between BsECD and FISH was weak but significant in HER2+ pts (R=0.35, p<0.0001) but not in HER2-ve pts (R=0.03, p=0.362). Unlike for HER2+ tumors, BsECD+ did not predict benefit in PFS from L in pts with HER2-ve tumors. HR: Hazard Ratio In pts with HER2- ve tumors, median ECD levels were stable in the P arm but increased slightly (4 ng/mL) in the L arm. In the HER2+ group, median levels in the P arm declined (3.5 ng/mL) but increased at 4 wk in L arm (3.4 ng/mL) and were stable thereafter. Conversion from sECD-ve to sECD+ was observed in both arms but did not correlate with outcome or provide predictive value. Data related to ECD status conversion will be reported. Conclusions: BsECD+ status correlates with HER2+ tumor status and may predict L benefit but BsECD+ status did not predict benefit in pts with HER2-ve tumors. On therapy changes in median sECD were small. Conversion from BsECD-ve to sECD+ did not predict L benefit and we could not confirm that evaluation of on treatment ECD status may help treatment decision.

[Table: see text]

[Table: see text]

Neoadjuvant dose-dense docetaxel, carboplatinum, and trastuzumab (ddTCH) chemotherapy for HER2 overexpressing breast cancer

e11557

Background: Neoadjuvant chemotherapy for locally advanced breast cancer was shown to improve the complete pathologic (pCR) and clinical response (cCR) as well as the disease free survival (DFS). Docetaxel, cisplatin, and trastuzumab given every 21 days in her2-positive breast cancer demonstrated a pCR rate of 23%. The concept of dose dense chemotherapy regimens has attracted much attention and we hypothesized that dose-dense regimen would further improve pCR, cCR and would maintain the safety profile while being a suitable regimen for outpatient administration. Methods: 48 patients with stage II/III HER2-positive breast cancer were prospectively enrolled on a clinical trial of a neoadjuvant regimen consisting of docetaxel 70 mg/m2 on days 1, 15, 29, and 43; carboplatinum at an AUC of 6 on days 1, 15, 29, and 43; trastuzumab 4 mg/kg on day 1 and 2 mg/kg weekly x 10 starting on day 8; peg-filgastrim 6 mg on days 2, 16, 30, and 44. Results: The median age was 50 years (range 30–78). 52% of patients were premenopausal, 63% and 22% were of Hispanic and African descent, respectively. Estrogen receptor was positive in 52% patients and median tumor size was 5 cm at the time of diagnosis. TNM stage distribution at presentation: T1 2%, T2 25%, T3 57%, T4 16%; N0 29%, N1 46%, N2 16%, N3 7%; M0 100%. pCR in breast; axilla; and both breast and axilla was observed in 19 of 44 patients (43.2%; 95% CI 28.3% - 59.0%); in 29 of 44 patients (65.9%; 95% CI 50.1% - 79.5%); and in 16 of 44 patients (36.4%; 95% CI 22.4% - 52.2%), respectively. No grade 4 or 5 toxicity occurred. The most frequent grade 3 toxicities were hand-foot syndrome (7%), neutropenia (4%), nausea/vomiting (2%), and bone pain (2%). Grade 2 cardiotoxicity was seen in 8% of patients and no grade 3 cardiotoxicity was observed. Conclusions: This neoadjuvant regimen was well tolerated and yielded a good pCR rate for this high risk group of patients.

No significant financial relationships to disclose.

Distinct multiethnic genome-wide alterations in breast cancer using paraffin embedded samples: preliminary analysis

Abstract #2024

Background and Rational: Ethnic-specific disparities in breast cancer (BC) stage of presentation and survival rates are well documented. To further investigate possible ethnic-specific genetic contributions to these disparities, we are completing gene expression profiling studies in a multi-ethnic cohort consisting of thirty “Triple Negative” BC patients [10 each African-American (AA), Hispanic (His) and non-Hispanic white (Cauc) women] matched for age of diagnosis and hormone receptor status. The overall study aim is an increased understanding of the biological basis of ethnic-specific BC disparities, leading ultimately to individualized, ethnic-specific diagnostic and therapeutic approaches. Two immediate study goals are to demonstrate the utility of FFPE samples in obtaining consistent, reproducible data from gene expression arrays, and secondly, to identify differentially expressed genes between tumor and normal tissue that are common or unique among the three ethnic groups. Methods: Pathology specimens were freshly cut from FFPE blocks and marked by a pathologist as to normal vs. tumor tissue. RNA isolation, labeled cDNA preparation, and hybridization of tumor and normal cDNAs to a breast cancer focused gene expression microarray (Breast Cancer DSA Research Tool) was performed by Almac Diagnostics. Each patient was self-matched (tumor vs. normal tissue) for gene expression studies. Results: Using 36 matched tumor and normal FFPE samples from 18 patients, approximately 17516 transcripts were detected on the Breast Cancer DSA with intensity significantly greater than background. For normal and tumor tissue samples, 9399 and 10,296 transcripts respectively, were detected in all three ethnic groups. Importantly, a subset of transcripts (hundreds to one thousand) was detected in only one or two ethnic groups. Using two-way ANOVA (disease state and ethnicity), a subset of 6479 transcripts was identified with p-value less than 0.01 in the statistical test and was selected and further used in data quality control. Data QC indicated that patient samples clustered well with respect to both ethnicity and normal versus tumor tissue. Additional analytical methods included K-means 2-Dimensional clustering and Principal Component Analysis. From these analyses, we identified ethnic-specific expression patterns in the matched normal and tumor tissue samples. We are completing these studies by increasing sample size and matching for stage of diagnosis, mapping clusters of differentially-expressed genes in pathway analysis, and validation by real-time PCR. In the longer term, DNA copy number variation (CNV) and chromosomal alterations will be investigated by high density arrays. Summary: These preliminary analyses shows that high quality gene expression data can be generated from FFPE samples, and that ethnic specific gene expression differences can be detected in tumor and matched normal breast tissue samples across ethnic groups.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2024.

Baseline serum extracellular domain HER2 expression in hormone receptor-positive metastatic breast cancer: correlation with known tissue HER2 status

Abstract #3147

Background: The extracellular domain (ECD) of the HER2 protein is cleaved by metalloproteases and shed into the serum. Serum ECD (sECD) HER2 can be detected by ELISA and may have prognostic/predictive associations in patients (pts) with breast cancer. Although use of sECD HER2 as a surrogate for HER2 overexpression in hormone receptor-positive (HR+) metastatic breast cancer (MBC) is controversial, seroconversion can occur at disease relapse and may reflect a change in tumor HER2 status that is associated with a poorer prognosis. EGF30008 is a double-blind, placebo-controlled, first-line, phase III trial of letrozole with/without lapatinib in 1,286 postmenopausal women with HR+ MBC. We report baseline sECD HER2 at study entry on all pts and the association with original tumor HER2 status.&#x2028; Methods: Serum samples were collected at study entry and every 4 weeks on study, including at disease progression. Patients were defined as sECD HER2+ if baseline sECD HER2 was ≥15 ng/mL. HER2 status was evaluated in tumor tissue by both immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH), using conventional cutoffs. To assess the correlation between baseline sECD HER2 and tumor tissue HER2 status, odds ratios (OR) with 95% confidence intervals (CI) and sensitivity/specificity (tumor tissue HER2 status as standard) were calculated. Data were from a blinded cutoff on 12May08. These analyses will be repeated after the database is finalized and unblinded.&#x2028; Results: Mean age was 63 ± 9.8 years. All pts had a HR+ original tumor, and 217 (17%) pts were confirmed as HER2+ by IHC or FISH. Median time from primary diagnosis to MBC was&#x2028; 3.3 years (range 0 - 33.9 yrs). Baseline sECD HER2 levels ranged from 2.5 to &gt; 560 ng/mL (mean 21 ± 60 ng/mL) with a bimodal distribution consistent with previously published data. The mean was 62 ng/mL (range 2.8 to &gt; 560 ng/mL) for HER2+ pts and 12 ng/mL (range 2.5 to 113.1 ng/mL) for HER2-negative pts. The OR between sECD HER2 at study entry and HER2 status of the original tumor was 4.5 (95% CI: 3.2, 6.2) with 42% sensitivity and 86% specificity.&#x2028; Conclusions: This OR suggests some correlation exists between baseline sECD HER2 and original tumor HER2 status. We cannot assess the rate of seroconversion that may have occurred from primary diagnosis until MBC at study entry. The bimodal distribution suggests that a clear cohort of pts exists at the time of relapse/study entry who are positive for sECD HER2. Analyses are evaluating whether subsequent changes in sECD HER2 levels occur over time during therapy, whether seroconversion predicts for a shorter time to relapse during letrozole monotherapy, and whether any differences exist in sECD HER2 levels over time for pts treated with letrozole plus lapatinib are ongoing.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3147.

BCIRG 007: First overall survival analysis of randomized phase III trial of trastuzumab plus docetaxel with or without carboplatin as first line therapy in HER2 amplified metastatic breast cancer (MBC)

LBA1008

Background: Based on preclinical synergism between docetaxel (T), carboplatin (C) and trastuzumab (H), BCIRG conducted a phase III trial in HER2-positive MBC to evaluate efficacy and safety of H in combination with T or TC. Methods: 263 patients (pts) with HER2 FISH+ MBC were randomized to TH (H with T 100mg/m2) or TCH (H with T 75mg/m2 and C AUC=6). Chemotherapy was given every 3 weeks (q3w) for 8 cycles with weekly H at 2mg/kg (loading dose of 4 mg/kg) followed by H q3w at 6 mg/kg until progression. Pts were stratified by centre and prior (neo) adjuvant taxane chemotherapy. Primary endpoint was Time To disease Progression (TTP). Secondary endpoints include overall survival, response rate, duration of response (DR), clinical benefit (CB) and safety. Results: 131 pts were treated in each arm Pt characteristics were well balanced in both groups. A first efficacy analysis was conducted at 204 events. There was no significant difference between TH and TCH in median TTP (11.1 vs 10.4 mos, p=0.57), ORR (73% in both arms), DR (10.7 vs 9.4 mos) and CB (67% in both arms). At 39 months of median follow-up, median overall survival was 36.40 and 36.57 months in TH and TCH arms respectively. More patients on TCH received the max number of chemotherapy cycles, and numerically fewer patients on TCH discontinued treatment as a result of non hematological toxicity. The most common gr 3/4 toxicities were: Neutropenic infection that was 16.8% vs 9.2% respectively for TH and TCH, thrombocytopenia (2% vs 15%), asthenia (5% vs 12%), anemia (5% vs 11%), and diarrhea (2% vs 10%). Two pts died (1.5%) due to sepsis in TCH. Absolute LVEF decline > 15 % were seen in 5.5 % vs 6.7 % of pts. One pt (0.8%) had a symptomatic CHF in TH arm. Conclusion: Both TH (T 100) and TCH (T 75) were highly effective treatment regimens in women having HER2-positive MBC, demonstrating high response rates, median TTP > 10 months, and median overall survival > 36 months in both TH and TCH. Cardiac toxicity was no significant problem with either treatment.

[Table: see text]

A phase I pharmacokinetic study of PR-104, a hypoxia-targeting agent, in patients with solid tumors

3516

Background: PR-104 is a novel pre-prodrug (precursor of a prodrug) designed to form a cytotoxic nitrogen mustard (alkylating agent) in hypoxic regions of tumors. Following IV administration, PR-104 is converted by systemic phosphatases to the alcohol intermediate PR-104A, which, under hypoxic conditions, is reduced to form the active DNA-crosslinking mustard species PR-104H. This phase I trial defines a Maximally Tolerated Dose (MTD) and pharmacokinetics (PK) for this schedule. Methods: Patients (pts) with relapsed/recurrent solid tumors received PR-104 as a 1-hour IV infusion every 3 weeks with PK sampling on days 1–2 of cycle 1. Cohorts of ≥3 pts were treated starting at 135 mg/m2. Results: 23 pts have been enrolled: median age 51 years (range 29–72); 13 (57%) male. Most pts had received prior radiation or chemotherapy and had metastatic disease. Six dose levels (135, 216, 354, 550, 770, and 1,100 mg/m2) have been evaluated. Dose-limiting toxicity (DLT) was observed in one patient at 1,100 mg/m2 (grade 3 fatigue) and this dose level was expanded to 6 pts. In the first 4 cohorts, 54 adverse events (AEs) were considered drug-related by the investigator including nausea (26% of all AEs), fatigue (19%), vomiting (11%) and anorexia (6%); remaining AEs each constituted < 3% of the total. Of 16 grade 3 AEs, 3 were considered drug-related by the investigator (anemia, dehydration and vomiting). Prophylactic anti-emetics largely prevented nausea and vomiting at higher doses, at which dose-related decreases in neutrophils and platelets were seen. Conclusions: PR-104 has shown manageable toxicities similar to other cytotoxic agents, with no serious mucositis, diarrhea or alopecia. DLT is likely to be myelosuppression based on preclinical and current clinical data, with the MTD close to 1,100 mg/m2. The preclinical PK target for the alcohol intermediate has been exceeded at higher doses and, while no objective responses have been documented, reductions in tumor volume have been seen at these doses.

[Table: see text]

No significant financial relationships to disclose.

Insulin-like growth factor I receptor (IGF-IR) inhibition in trastuzumab (T) resistant HER2+ breast cancer (BrCa) cells

14049

Background: IGF-IR signaling interferes with the growth inhibitory action of T in BrCa cell lines and may play a role in clinical resistance to T. We studied the effect of IGF-IR inhibition on T resistance. Methods: HER2 and IGF-IR protein levels were determined by ELISA. T growth inhibition of HER2+ BrCa cell lines was measured by cell counting. HER2 and IGF-IR activity were determined by immunoprecipitation with HER2 and IGF-IR antibodies, followed by western blotting with phospho-tyrosine antibody. The effects of IGF- I/IGF-IR inhibition on proliferation and response to T were investigated. Results: No significant correlation was found between HER2, phospho-HER2 or IGF-IR levels and response to T in 12 HER+ BrCa lines. However, two T-conditioned cell lines show resistance to T (BT474 - 2.6 fold; SKBR3 - 1.8 fold) and have higher levels of phospho-IGF-IR compared to parental cell lines. Neither IGFBP3 nor IGF-IR antibody aIR3 significantly inhibited the growth of T-conditioned cell lines or enhanced the anti-proliferative effects of T. IGF-IR siRNA decreased IGF-IR protein levels and inhibited proliferation (29.8 ± 9.3 %) of T-conditioned SKBR3 cells. IGF-IR siRNA also enhanced T growth inhibition of T-conditioned SKBR3 cells (47.7 ± 13.7 % compared to 17.7 ± 14.8 % for T alone). The small molecule IGF-IR tyrosine kinase inhibitor (TKI), NVP-AEW541, inhibited growth of parental and T-conditioned SKBR3 cells and enhanced response to T (Table). Conclusions: Increased activation of IGF-IR may play a role in resistance to T. Inhibition of IGF-I ligand binding does not appear to alter IGF-IR mediated T-resistance. However, reducing IGF-IR protein levels or blocking IGF-IR TK activity improves response to T in resistant cells. Thus, the combination of IGF-IR TKIs, such as NVP-AEW541, with T may be beneficial for T-resistant HER2+ BrCa.

[Table: see text]

[Table: see text]

BCIRG 007: Randomized phase III trial of trastuzumab plus docetaxel with or without carboplatin first line in HER2 positive metastatic breast cancer (MBC)

LBA516

Background: Based on preclinical synergism between docetaxel (T), carboplatin (C) and trastuzumab (H), BCIRG conducted a phase III trial for women with HER2+ MBC to evaluate efficacy and safety of H in combination with T or TC. Methods: 263 patients (pts) with HER2 FISH+ MBC were randomized to TH, (H with T 100 mg/m2) or TCH, (H with T 75 mg/m2 and C AUC=6). Chemo was given q3 wks for 8 cycles with wkly H at 2 mg/kg (loading dose of 4 mg/kg), followed by H q3 wks at 6 mg/kg until progression. Pts were stratified by centre and prior (neo) adjuvant taxane chemotherapy. Primary endpoint was TTP with 80% power (0.05 significance) to detect a 50% improvement in median TTP between the 2 arms. Secondary endpoints include overall survival, response rate, duration of response (DR), clinical benefit (CB) and safety. Results: 131 pts were treated in each arm. Pt characteristics were well balanced in both groups. Importantly, only 52% of pts received C at the protocol specified dose (RDI > 0.9). Efficacy analysis was conducted at 204 events. There was no significant difference between TH and TCH in median TTP (11.1 vs 10.4 mos, p = 0.57), ORR (73% in both arms), DR (10.7 vs 9.4 mos) and CB (67% in both arms). The most common gr 3/4 toxicities were: infection (44% vs 30%), neutropenic infection (22% vs 12%), thrombocytopenia (2% vs 15%), febrile neutropenia (12% vs 13%) asthenia (5% vs 12%), anemia (5% vs 11%), and diarrhea (2% vs 9%). Two pts died (1.5%) due to sepsis in TCH. Absolute LVEF decline > 15% were seen in 5.5% vs 6.7% of pts. One pt (0.8%) had a symptomatic CHF in TH arm Conclusions: The already effective TH regimen does not benefit from the addition of C, when the T dose in TH is 100 mg/m2 and 75 mg/m2 in TCH, in women with HER2+ MBC.

No significant financial relationships to disclose.

Anti-VEGF antibody bevacizumab (Avastin) with 5FU/LV as third line treatment for colorectal cancer

BACKGROUND

To evaluate the activity and safety of bevacizumab when given with standard 5FU/leukovorin (LV) regimens in patients with metastatic colorectal cancer who have failed irinotecan and oxaliplatin-based treatments.

METHODS

Bevacizumab was given at 5 mg/kg as an IV infusion every 2 weeks. Patients received 5FU according to Roswell Park or the de Gramont regimen.

RESULTS

Nineteen patients enrolled, median age 60, median PS: 1. Most common toxicity attributable to bevacizumab was mild hypertension, epistaxis and mild proteinuria; 1 patient had a CNS haemorrhage. The median number of cycles was 1 (8 weeks). Clinical benefit as disease stabilisation lasting 2-6 months was noted in 9 patients, whereas 10 progressed (median f/u: 5 months). TTP was 16 weeks, and the overall survival has not been reached (24+ weeks).

CONCLUSIONS

Bevacizumab may result in growth arrest and clinical benefit in a substantial proportion of patients with colorectal cancer and no alternative treatment.

HER-2/neu overexpression and in vitro chemosensitivity to CMF and FEC in primary breast cancer

Available clinical and experimental data on the effect of HER-2/neu overexpression on chemosensitivity are controversial. It was the purpose of this in vitro study to define the association between HER-2/neu overexpression and the sensitivity to the chemotherapeutic drug combinations of cyclophosphamide, methotrexate and 5-fluorouracil (CMF) and 5-fluorouracil, epirubicin and cyclophosphamide (FEC) of breast cancer cells derived from 140 chemotherapy-naïve patients at the time of primary surgery. Both drug combinations were tested at six different concentrations ranging from 6.25-200% peak plasma concentration (PPC). Immunohistochemical detection of HER-2/neu overexpression was performed with the HER-2/neu antibodies, CB11, TAB250 and AO485, in the same tumor specimens. Immunoreactions were determined as negative (0/1+), weakly positive (2+) and strongly positive (3+). However, the antibodies varied in their degrees of sensitivity. Breast cancer samples with strong (3+) HER-2/neu overexpression demonstrated 90% growth inhibition (IC90) at significantly lower PPC values, using the CB11 (p = 0.048), TAB250 (p = 0.007) and AO485 (p < or =0.01) antibodies, and showed 50% growth inhibition (IC50) at significantly lower PPC values, using the CB11 antibody (p = 0.01) compared to their counterparts with lower levels of HER-2/neu expression. When analyzing the group of patients with intermediate and strong HER-2/neu overexpression (2+ and 3+), an association between HER-2/neu overexpression and increased chemosensitivity was seen with the TAB250 (p = 0.044) and AO485 (p = 0.032) antibodies, but not with the CB11 antibody (p =0.8) at the IC90 level. Differences in chemosensitivity between samples with strong HER-2/neu overexpression and those with lower levels were then analyzed separately for CMF and FEC. Both regimens achieved 90% tumor growth inhibition at lower PPC values in samples with strong HER-2/neu overexpression (3+) compared to their counterparts with lower expression levels (AO485 p = 0.011 for CMF, and p = 0.09 for FEC). Cumulative concentration-response plots of tumors responding in vitro with 90% tumor cell inhibition showed a stronger dose dependence for both CMF and FEC among tumor samples with strong HER-2/neu overexpression compared to those with lower levels of expression. In conclusion, the data show that HER-2/neu overexpression was not associated with in vitro drug resistance to CMF or FEC. In contrast, tumors with strong HER-2/neu overexpression demonstrated increased dose-dependent in vitro sensitivity to both the FEC and CMF regimens.

Her-2/neu and urokinase-type plasminogen activator and its inhibitor in breast cancer

PURPOSE

Recent studies suggest that HER-2/neu specifically promotes the invasive capacity of tumor cells by up-regulating secretion of the proteolytic enzyme, urokinase-type plasminogen activator (uPA), or its inhibitor, plasminogen activator inhibitor-1 (PAI-1), in colon and gastric cancer. It was the purpose of this study to: (a) evaluate the association between HER-2/neu and uPA and PAI-1 expression in a large primary breast cancer cohort; (b) perform the first multivariate analysis, including HER-2/neu, uPA, and PAI-1 in breast cancer; and (c) define the effect of HER-2/neu overexpression on uPA and PAI-1 expression in breast cancer cells.

EXPERIMENTAL DESIGN

HER-2/neu, uPA, and PAI-1 were measured as continuous variables by ELISA in primary breast cancer tissue extracts from 587 patients with clinical follow-up and analyzed for correlations with clinical outcome. Furthermore, a full-length human HER-2/neu cDNA was introduced into five human breast cancer cell lines to define the effects of HER-2/neu overexpression on uPA and PAI-1 expression. In addition, we tested whether HER-2/neu antibodies could reverse any given alteration of uPA and PAI-1 levels.

RESULTS

Our findings indicate a weak positive association between HER-2/neu and uPA (r = 0.147; P < 0.001) and no association between HER-2/neu and PAI-1 (r = 0.07; P = 0.085). HER-2/neu overexpression (> or =400 fmol/mg) and high levels of uPA/PAI-1 (> or =5.5 ng/mg and/or > or =14 ng/mg, respectively) were significantly associated with shorter disease-free survival (DFS; P < 0.001 and P = 0.003) and metastasis-free survival (MFS; P = 0.015 and P < 0.001). Multivariate analysis revealed prognostic independence between HER-2/neu and the uPA/PAI-1 axis for DFS and MFS. Both uPA and PAI-1 had no significant discriminatory effect among HER-2/neu-positive patients for DFS. The prognostic value of HER-2/neu overexpression for MFS, however, was significantly enhanced by elevated uPA expression (P = 0.053). Stable transfection of the HER-2/neu gene into multiple human breast cancer cell lines resulted in consistent down-regulation of uPA or PAI-1 expression. In addition, anti-HER-2/neu antibodies did not significantly affect uPA or PAI-1 expression in human cancer cell lines naturally overexpressing HER-2/neu.

CONCLUSIONS

The present findings suggest that the invasive phenotype elicited by HER-2/neu overexpression in breast cancer is not a direct effect of uPA or PAI-1 expression. HER-2/neu and the uPA/PAI-1 axis have been shown to affect the invasive capacity of breast cancer independently. Determination of uPA can provide significant additional prognostic information for MFS in HER-2/neu-positive and -negative patients.

Association of urokinase-type plasminogen activator and its inhibitor with disease progression and prognosis in ovarian cancer

PURPOSE

Urokinase-type plasminogen activator (uPA) and its inhibitor, plasminogen activator inhibitor (PAI)-1, have been shown to be related to poor prognosis in a variety of malignant solid tumors. Studies on the prognostic relevance of uPA and PAI-1 in ovarian cancer, however, have been inconclusive. The current study tests the hypothesis that elevated expression of uPA and PAI-1 is associated with prognosis and disease progression.

EXPERIMENTAL DESIGN

uPA and PAI-1 were prospectively measured by quantitative ELISA in tumor samples from 103 ovarian cancer patients (82 primary invasive epithelial carcinomas, 9 low malignant potential tumors, and 12 recurrent ovarian carcinomas).

RESULTS

uPA but not PAI-1 levels were consistently associated with malignant progression, with levels increased from low malignant potential tumors to primary tumors (uPA, P = 0.04; PAI-1, P = 0.019), from early to advanced disease stages (uPA, P = 0.014; PAI-1, P = 0.23), and from primary to intra-abdominal metastatic tumors (uPA, P = 0.001; PAI-1, P = 0.16). High uPA and PAI-1 levels were associated with residual tumor volumes of >1 cm (P = 0.001 and P = 0.016, respectively). Among invasive International Federation of Gynecologists and Obstetrician stages I-IV tumors, elevated levels of uPA (>5.5 ng/mg) and PAI-I (>18.8 ng/ml) were associated with a shortened progression-free survival (uPA, P = 0.003; PAI-1, P = 0.039) and overall survival (uPA, P = 0.0002; PAI-1, P = 0.007). In multivariate analysis, uPA retained prognostic independence for progression-free survival (P = 0.037) and overall survival (P = 0.006).

CONCLUSIONS

These data suggest that the uPA/PAI-1 axis may play an important role in the intra-abdominal spread and reimplantation of ovarian cancer cells. The prognostic relevance of uPA and PAI-1 supports their possible role in the malignant progression of ovarian cancer.