Abstract OT1-03-14: SANDPIPER: Phase III study of the PI3-kinase inhibitor taselisib (GDC-0032) plus fulvestrant in patients with estrogen receptor-positive, HER2-negative locally advanced or metastatic breast cancer enriched for patients with PIK3CA-mutant tumors

Background: PIK3CA mutations are one of the most frequent genomic alterations in breast cancer (BC), being present in ∼40% of estrogen receptor (ER)-positive, HER2-negative breast tumors. PIK3CA mutations promote growth and proliferation of tumors and mediate resistance to endocrine therapies in BC. Taselisib is a potent and selective PI3-kinase (PI3K) inhibitor that displays greater selectivity for mutant PI3Kα than wild-type PI3Kα. Taselisib has enhanced activity against PIK3CA-mutant BC cell lines, and clinical data include confirmed partial responses in patients with PIK3CA-mutant BC treated with taselisib either as a single agent or in combination with fulvestrant.

Trial design: SANDPIPER is a double-blind, placebo-controlled, randomized, phase III study, designed to evaluate efficacy and safety of taselisib plus fulvestrant in patients with ER-positive, HER2-negative locally advanced or metastatic BC. Patients will be randomized 2:1 to receive either taselisib (4 mg daily) or placebo in combination with fulvestrant (500 mg intramuscular on Days 1 and 15 of Cycle 1, and on Day 1 of each subsequent 28-day cycle). Randomization will be stratified by visceral disease, endocrine sensitivity, and geographical region. The study enriches for patients with PIK3CA-mutant tumors who will be randomized separately from patients with non-mutant tumors.

Eligibility: Postmenopausal women with ER-positive, HER2-negative, locally advanced or metastatic BC are eligible if they have disease recurrence or progression during or after aromatase inhibitor treatment. A valid PIK3CA-mutation result via central assessment is required prior to enrollment.

Aims: The primary efficacy endpoint is investigator-assessed progression-free survival (PFS) in patients with PIK3CA-mutant tumors. Other endpoints include overall survival (OS), objective response rate (ORR), clinical benefit rate (CBR), duration of objective response, safety, pharmacokinetics, and patient-reported outcomes. Efficacy in patients without PIK3CA-mutant tumors will be an exploratory endpoint.

Statistical methods: The primary efficacy analysis population will include all randomized patients with PIK3CA-mutant tumors. Patients will be grouped according to treatment arm assigned at randomization. Median PFS and OS will be estimated using Kaplan-Meier methodology in each treatment arm. Cox proportional-hazards models will be used to estimate the hazard ratio with 95% confidence intervals (CIs). ORR, CBR, and their 95% CIs will be estimated by treatment arms. Duration of objective response will be estimated by treatment arms using the Kaplan-Meier methodology. Quality of life will be analyzed and summarized by treatment arms. Safety will be analyzed for all treated patients according to actual treatment received.

Accrual: Target enrollment is 600 pts from ∼165 sites and ∼23 countries. The study is open for enrollment and 11 patients have been enrolled as of May 31, 2015. Clinicaltrials.gov ID: NCT02340221.

Contact information: For more information or to refer a patient, email global.rochegenentechtrials@roche.com or call 1-888-662-6728 (USA only).

Citation Format: Baselga J, Cortés J, De Laurentiis M, Diéras V, Harbeck N, Hsu J, Jin H, Schimmoller F, Wilson TR, Im Y-H, Jacot W, Krop IE, Verma S. SANDPIPER: Phase III study of the PI3-kinase inhibitor taselisib (GDC-0032) plus fulvestrant in patients with estrogen receptor-positive, HER2-negative locally advanced or metastatic breast cancer enriched for patients with PIK3CA-mutant tumors. [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 OT1-03-14.

Abstract P6-05-02: Intrinsic subtype and gene expression changes between primary and metastatic breast cancer

Background: A better understanding of the biological changes occurring during metastatic progression of breast cancer is needed to identify new biomarkers, targets and novel treatment strategies. Here, we compared the intrinsic subtype and the expression of a gene panel across a large dataset of paired primary and metastatic tissues.

Methods: Expression profiling of 105 breast cancer-related genes was performed on 254 (127 pairs) formalin-fixed paraffin-embedded tumor tissues using the nCounter platform. Tumor samples were obtained from 3 independent sources (ConvertHER trial [BCRT 2014] and two in-house datasets). Tumors were classified into each intrinsic subtype using the research-based PAM50 classifier (Parker et al. J Clin Oncol 2009). Chi-square tests were performed to determine the differences in the distribution of variables. Paired two-class Significance of Microarrays (SAM) was performed to determine the genes differentially expressed between paired primary and metastatic tissues. In vitro stable transfection of FGFR4-GFP was performed on Luminal B MCF7 cell line. RNA was purified on control vs. transfected cell lines. 7-AAD cell viability was performed following estrogen deprivation for 6 days.

Results: Subtype distribution in primary vs. metastatic disease was 39.0% vs. 26.8% for Luminal A (p=0.012), 26.0% vs. 35.0% for Luminal B (p=0.322), 11.4% vs. 20.3% for HER2-enriched (p=0.115) and 10.6% vs. 13.0% for Basal-like tumors (p=0.843). The rate of subtype conversion was 7.7% in Basal-like, 23.1% in HER2-enriched, 30.0% in Luminal B and 54.3% in Luminal A disease. The majority of subtype conversions in Luminal A disease were to Luminal B (72.0%) and HER2-enriched (24.0%). Overall, 13.2% of primary Luminal A/B tumors progressed to a HER2-E subtype despite 70% of them being clinically HER2-negative. In a paired analysis using all samples, 10- and 12- genes were found up- and down- regulated in metastatic tissues (False Discovery Rate [FDR] <5%). The up-regulated gene list in metastatic disease was composed of FGFR4 (top gene) and proliferation genes (CDC6, CCNB1, CEP55). The down-regulated gene list in metastatic disease was enriched for luminal-related genes (ESR1, PGR, NAT1 and MAPT). A similar paired analysis within Luminal A, Luminal B, HER2-enriched and Basal-like disease revealed 22, 8, 7 and 0 differentially expressed genes (FDR<5%), respectively. Finally, MCF7 cell line transfected with FGFR4 showed a relative increase in the HER2-enriched profile compared with transfected control. In vitro, MCF7-FGFR4 cells showed estrogen independent growth compared to transfected controls.

Conclusions: Metastatic tissues are relatively more proliferative and less luminal compared to primary tumors. This is especially relevant in primary Luminal A disease. In contrast, metastatic tissues from Basal-like primary disease remain largely unchanged. In luminal disease, a significant increase in the HER2-enriched profile is observed in metastatic disease despite most tumors being clinically HER2-negative. A potential driver of the HER2-enriched profile and estrogen independence in clinically HER2-negative metastatic tissues might be FGFR4.

Citation Format: Prat A, Martínez de Dueñas E, Galván P, Garcia S, Burgués O, Paré L, Antolín S, Martinello R, Blancas I, Adamo B, Guerrero Á, Muñoz M, Nuciforo P, Vidal M, Pérez RM, Chacón JI, Caballero R, Gascón P, Carrasco E, Rojo F, Perou CM, Cortés J, Adamo V, Albanell J, Lluch A. Intrinsic subtype and gene expression changes between primary and metastatic breast cancer. [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 P6-05-02.

Abstract P4-07-04: PARP1/2 inhibition in a subset of triple negative breast cancer (TNBC) patient-derived tumor xenografts (PDX) identifies predictive biomarkers of response

Background: BRCA1/2 mutation carriers (gBRCA) have a higher risk of breast or ovarian cancer, since BRCA1/2 mutation results in impaired high-fidelity DNA repair by homologous recombination (HR) and subsequently genetic instability. In non-gBRCA TNBC, HR deficiency occurs at the somatic level, by means of BRCA1 mutation, BRCA1 epigenetic loss or mutation in other HR-associated genes. Because PARP1/2 inhibitors (PARPi) are well-tolerated and active anti-cancer agents in the advanced setting of gBRCA tumors, we sought to expand their applicability by identifying response biomarkers in TNBC.

Methods: We have assessed the antitumor response of the PARP1/2 inhibitor olaparib as single agent in a panel of 12 primary and advanced TNBC PDX models. On PDXs exhibiting primary sensitivity to olaparib, we have developed models of acquired resistance by continuous exposure to the drug and identifying progression on treatment. We have characterized the models through targeted sequencing and the analysis of the hypermethylation and expression levels of BRCA1 transcript to find potential correlates of drug-sensitivity.

Results: Three out of 12 PDXs (25%) treated with single agent olaparib, exhibit tumor regression or disease stabilization. BRCA1 is hypermethylated in two of these PARPi-sensitive TNBC PDX models and is associated with loss of BRCA1 mRNA expression. The third PARPi-sensitive TNBC PDX harbors a frameshift, heterozygous PALB2 mutation, which is no longer detected in the acquired resistance PDX model. Acquired resistance in the hypermethylated PDXs is under study as well as the duration of response compared to gBRCA PDX models.

Conclusions: Our study highlights that somatic HR-deficiency is frequent in TNBC and provides the basis of sensitivity to PARPi.

Citation Format: Serra V, Cruz C, Bruna A, Ibrahim YH, Vivancos A, Vivancos A, Nuciforo P, Bellet M, Gómez P, Pérez JM, Saura C, Vidal M, Serres X, Rueda OM, Peg V, Caldas C, O'Connor MJ, Baselga J, Cortés J. PARP1/2 inhibition in a subset of triple negative breast cancer (TNBC) patient-derived tumor xenografts (PDX) identifies predictive biomarkers of response. [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 P4-07-04.

Abstract P2-08-13: Integrating multiplex and next generation sequencing (NGS) platforms in routine molecular profiling of metastatic breast cancer (MBC) patients (pts): Trends for enrollment in genotype-directed clinical trials (GDTs)

Background/aims: Multiplex or NGS platforms increase the number of mutations (mut) detected in tumor samples respect to single-gene sequencing techniques. We aimed to assess the actionable molecular alteration (ActMA) detection rate and the enrollment in GDTs derived from the integration of these platforms in routine molecular profiling of MBC pts, in addition to FISH and IHC techniques already in use. Methods: Consecutive MBC pts screened for gene mut by Sequenom (Seq) or AmpliconSeq (ASeq) were identified. Data on FGFR1 amplification (amp), PTEN IHC, and enrollment in GDTs were collected. ActMA: any mut, PTENnull (IHC score=0), or FGFR1/HER2amp for which a matched targeted drug might be available. Targeted therapy: treatment with PI3K/mTOR, novel anti-HER2, FGFR, or AKT inhibitors (inh) irrespective of having ActMA. GDT: treatment matched to ActMA. Results: From Oct2010-Apr2015, 260 pts screened (Seq 207, ASeq 53). IHC subtype: HR+/HER2- (LUM) 65%, HER2+ 13.5%, TN 19.6%, unk 1.9%. 84 samples from a metastatic site (32.3%).

ActMA / n (%)LUMHER2+TNP value (Fisher's exact test)TotalTP53*11 (31.4)1 (50)9 (52.9)0.3421 (38.9)PIK3CA44 (26)10 (28.6)4 (7.8)0.158 (22.7)FGFR1amp21 (17.4)1 (5.3)6 (16.7)0.4728 (15.9)PTENnull12 (9.3)2 (7.7)9 (25)0.0323 (12)AKT110 (5.9)1 (2.9)-0.1511 (4.3)ERBB23 (1.8)---3 (1.2)EGFR1 (0.6)-2 (4.1)-3 (1.2)ESR1*1 (3)---1 (2)KRAS2 (1.2)---2 (0.8)Denominators vary according to platform. *Amplicon only

Proportion of PIK3CAmut was similar irrespective of the site of analysis (primary 25.5%, metastasis 21.4%; P=0.63) and platform (Seq 22.2%, ASeq 24.5%, P=0.72). ASeq detected more mutations in actionable genes than Seq (36% vs. 29%, P=0.01). At least 1 ActMA (range 0-3) was found in 53.5% of pts, with non-significant differences in HER2- subtypes (LUM 48.5% vs. TN 39.2%, P=0.32).

Subtype* / ActMA n (%)≥10123All139 (53.5)121 (46.5)111 (42.7)25 (9.6)3 (1.2)LUM82 (48.5)87 (51.5)71 (42)9 (5.3)2 (1.2)HER2+35 (100)-22 (62.9)12 (34.3)1 (28)TN20 (39.2)31 (60.8)16 (31.4)4 (7.8)-*5 pts with unk subtype not shown

Pts with ≥2 ActMA (excluding HER2amp): 11 LUM (interestingly, 3 pts with PIK3CAmut+FGFR1amp), 1 HER2+, and 4 TN. Overall, 56% of pts received ≥1 targeted therapy (range 0-4). From the 139 pts with ≥1 potential ActMA (including HER2amp if treated with a novel anti-HER2), 61.8% received a targeted therapy and 42.4% were enrolled in a GDT: PI3K/mTOR inhibitor (inh) 54 (64.3%), novel anti-HER2 16 (19.1%), FGFR inh 8 (9.5%), AKT inh 6 (7.1%). Of the 121 pts that did not have potentially ActMA, 50% received a targeted therapy. The OR for receiving targeted therapy if ActMA was present was 1.59 (95%CI 0.94-2.70, P=0.08). Conclusion: Integration of multiplex and NGS platforms in routine molecular profiling of MBC pts yields a detection rate of ActMA >50%, which translates into higher probability of receiving a targeted agent and enrollment in a GDT. This suggests that physicians are pushing towards matched targeted therapies for pts that participate in molecular screening programs and have ActMA. Results on the outcome of these pts will be presented.

Citation Format: Oliveira M, Dienstmann R, Bellet M, Pérez-Garcia JM, Gómez P, Muñoz-Couselo E, Vidal M, Ortega V, Zamora E, Soberino J, Meire A, Nuciforo P, Vivancos A, Cortés J, Saura C. Integrating multiplex and next generation sequencing (NGS) platforms in routine molecular profiling of metastatic breast cancer (MBC) patients (pts): Trends for enrollment in genotype-directed clinical trials (GDTs). [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 P2-08-13.

The expanding role of pertuzumab in the treatment of HER2-positive breast cancer

Breast cancer tumors that demonstrate gene amplification or overexpression of human epidermal growth factor receptor 2 (HER2) are classified as HER2-positive. They account for approximately 15% of all breast cancers and represent an adverse prognostic factor. Over the past years, many new therapies have become available for the treatment of breast cancer. Particularly, the treatment of patients with HER2-positive breast cancer has developed with the arrival of anti-HER2 targeted therapies that have been proven to increase survival in both the metastatic and early-stage settings of the disease. Trastuzumab, a monoclonal antibody targeting HER2, significantly improves survival in HER2-positive breast cancer. Nevertheless, it is still a challenge to evolve anti-HER2 therapies, as the disease may progress. Pertuzumab inhibits HER2 by binding to a different HER2 epitope than trastuzumab and represents a complementary mechanism of action to trastuzumab. The efficacy and safety of pertuzumab in combination with trastuzumab with or without chemotherapy have been demonstrated in both advanced and early stages of HER2-positive breast cancer. Herein, we review the available data on the use of pertuzumab for the treatment of patients with HER2-positive breast cancer.

MUC1/SEC and MUC1/Y overexpression is associated with inflammation in Sjögren's syndrome

OBJECTIVES

To evaluate the expression and localization of MUC1/SEC and MUC1/Y isoforms in labial salivary glands (LSG) from Sjögren's syndrome patients (SS patients), as well as their in vitro expression induced by cytokines.

SUBJECTS AND METHODS

Labial salivary gland from 27 primary SS patients and 22 non-SS sicca subjects were studied. Relative MUC1/SEC and MUC1/Y mRNA levels were determined by qPCR and protein levels by Western blotting. Induction of mucin mRNAs was assayed in vitro. Immunohistochemistry was used for localization.

RESULTS

Relative MUC1/SEC and MUC1/Y mRNA and protein levels were significantly higher in LSG from SS patients. These mRNAs were induced by cytokines. MUC1/SEC and MUC1/Y were detected in acini apical region of control LSGs, and significant cytoplasmic accumulation was observed in acini of SS patients. MUC1/Y localized in acinar nuclei and cytoplasm of inflammatory cells of LSG from SS patients. A strong positive correlation was observed between cellular MUC1/SEC levels and glandular function determined by scintigraphy.

CONCLUSIONS

We show for the first time that MUC1/SEC and MUC1/Y are expressed in LSG of both SS patients and non-SS sicca subjects. The observed overexpression and aberrant localization of MUC1/SEC and MUC1/Y and their induction by pro-inflammatory cytokines may favor the perpetuation of the inflammatory environment that disrupts the salivary glandular homeostasis in SS patients.

PCDD/PCDF and dl-PCB in the ambient air of a tropical Andean city: passive and active sampling measurements near industrial and vehicular pollution sources

Concentration gradients were observed in gas and particulate phases of PCDD/F originating from industrial and vehicular sources in the densely populated tropical Andean city of Manizales, using passive and active air samplers. Preliminary results suggest greater concentrations of dl-PCB in the mostly gaseous fraction (using quarterly passive samplers) and greater concentrations of PCDD/F in the mostly particle fraction (using daily active samplers). Dioxin-like PCB predominance was associated with the semi-volatility property, which depends on ambient temperature. Slight variations of ambient temperature in Manizales during the sampling period (15°C-27°C) may have triggered higher concentrations in all passive samples. This was the first passive air sampling monitoring of PCDD/F conducted in an urban area of Colombia. Passive sampling revealed that PCDD/F in combination with dioxin-like PCB ranged from 16 WHO-TEQ2005/m(3) near industrial sources to 7 WHO-TEQ2005/m(3) in an intermediate zone-a reduction of 56% over 2.8 km. Active sampling of particulate phase PCDD/F and dl-PCB were analyzed in PM10 samples. PCDD/F combined with dl-PCB ranged from 46 WHO-TEQ2005/m(3) near vehicular sources to 8 WHO-TEQ2005/m(3) in the same intermediate zone, a reduction of 83% over 2.6 km. Toxic equivalent quantities in both PCDD/F and dl-PCB decreased toward an intermediate zone of the city. Variations in congener profiles were consistent with variations expected from nearby sources, such as a secondary metallurgy plant, areas of concentrated vehicular emissions and a municipal solid waste incinerator (MSWI). These variations in congener profile measurements of dioxins and dl-PCBs in passive and active samples can be partly explained by congener variations expected from the various sources.

Expert perspectives on biosimilar monoclonal antibodies in breast cancer

While biosimilars of low molecular-weight biologics such as G-CSF have been available in Europe since 2006, biosimilars of monoclonal antibodies (mAbs) have only become available in the last year. Unlike G-CSF, mAbs are large and complex and often play a direct role in the survival of patients with life-threatening illnesses such as breast cancer. Several biosimilars are currently under development for the treatment of breast cancer, and the use of biosimilars in a setting that directly impacts patient survival raises a number of questions. In this review, we discuss the biosimilar mAbs currently in development for the treatment of breast cancer. We provide an overview of the European Medicine Agency guidelines and historic data on the development of biosimilars in order to discuss the development of biosimilar mAbs for breast cancer. Biosimilars offer a highly attractive path toward reducing the cost of medical care and should be pursued with great interest. However, for agents used to treat life-threatening diseases such as cancer, a cautious approach must be taken to ensure that there is no negative impact on patient care. Clinical trials for biosimilar mAbs must be carried out in an appropriately sensitive patient population using endpoints that can accurately demonstrate both the similarity of the biosimilar and its efficacy in the indication. Due to the abbreviated approval pathway, rigorous pharmacovigilance must be in place once a biosimilar mAb is approved in order to ensure its long-term safety and efficacy.

Incidence of central nervous system metastases in patients with HER2-positive metastatic breast cancer treated with pertuzumab, trastuzumab, and docetaxel: results from the randomized phase III study CLEOPATRA

BACKGROUND

Results from the phase III trial CLEOPATRA in human epidermal growth factor receptor 2-positive first-line metastatic breast cancer demonstrated significant improvements in progression-free and overall survival with pertuzumab, trastuzumab, and docetaxel over placebo, trastuzumab, and docetaxel. We carried out exploratory analyses of the incidence and time to development of central nervous system (CNS) metastases in patients from CLEOPATRA.

PATIENTS AND METHODS

Patients received pertuzumab/placebo: 840 mg in cycle 1, then 420 mg; trastuzumab: 8 mg/kg in cycle 1, then 6 mg/kg; docetaxel: initiated at 75 mg/m(2). Study drugs were administered i.v. every 3 weeks. The log-rank test was used for between-arm comparisons of time to CNS metastases as first site of disease progression and overall survival in patients with CNS metastases as first site of disease progression. The Kaplan-Meier approach was used to estimate median time to CNS metastases as first site of disease progression and median overall survival.

RESULTS

The incidence of CNS metastases as first site of disease progression was similar between arms; placebo arm: 51 of 406 (12.6%), pertuzumab arm: 55 of 402 (13.7%). Median time to development of CNS metastases as first site of disease progression was 11.9 months in the placebo arm and 15.0 months in the pertuzumab arm; hazard ratio (HR) = 0.58, 95% confidence interval (CI) 0.39-0.85, P = 0.0049. Overall survival in patients who developed CNS metastases as first site of disease progression showed a trend in favor of pertuzumab, trastuzumab, and docetaxel; HR = 0.66, 95% CI 0.39-1.11. Median overall survival was 26.3 versus 34.4 months in the placebo and pertuzumab arms, respectively. Treatment comparison of the survival curves was not statistically significant for the log-rank test (P = 0.1139), but significant for the Wilcoxon test (P = 0.0449).

CONCLUSIONS

While the incidence of CNS metastases was similar between arms, our results suggest that pertuzumab, trastuzumab, and docetaxel delays the onset of CNS disease compared with placebo, trastuzumab, and docetaxel.

CLINICALTRIALSGOV

NCT00567190.

Phase III trial of nonpegylated liposomal doxorubicin in combination with trastuzumab and paclitaxel in HER2-positive metastatic breast cancer

BACKGROUND

Nonpegylated liposomal doxorubicin liposomal doxorubicin, (Myocet™; Sopherion Therapeutics, Inc Canada, and Cephalon, Europe) (NPLD; Myocet(®)) in combination with trastuzumabHerceptin(®) (Hoffmann-La Roche) has shown promising activity and cardiac safety. We conducted a randomized phase III trial of first-line NPLD plus trastuzumab and paclitaxel (Pharmachemie B.V.) (MTP) versus trastuzumab plus paclitaxel (TP) in patients with human epidermal growth factor 2 receptor (HER2)-positive metastatic breast cancer.

PATIENTS AND METHODS

Patients were randomly assigned to NPLD (M, 50 mg/m(2) every 3 weeks for six cycles), trastuzumab (T, 4 mg/kg loading dose followed by 2 mg/kg weekly), and paclitaxel (P, 80 mg/m(2) weekly) or T + P at the same doses until progression or toxicity. The primary efficacy outcome was progression-free survival (PFS).

RESULTS

One hundred and eighty-one patients were allocated to receive MTP, and 183 to TP. Median PFS was 16.1 and 14.5 months with MTP and TP, respectively [hazard ratio (HR) 0.84; two-sided P = 0.174]. In patients with estrogen receptor (ER)- and progesterone receptor (PR)-negative tumors, PFS was 20.7 and 14.0 months, respectively [HR 0.68; 95% confidence interval (CI) 0.47-0.99]. Median overall survival (OS) was 33.6 and 28.9 months with MTP and TP, respectively (HR 0.79; two-sided P = 0.083). In ER- and PR-negative tumors, OS was 38.2 and 27.9 months, respectively (HR 0.63; 95% CI 0.42-0.93). The frequency of adverse events was higher with MTP, but there was no significant difference in cardiac toxicity between treatment arms.

CONCLUSION(S)

The trial failed to demonstrate a significant clinical improvement with the addition of M to TP regimen. The clinical benefit observed in an exploratory analysis in the ER- and PR-negative population deserves consideration for further clinical trials.

CLINICAL TRIAL NUMBER

NCT00294996.

Abstract P5-08-06: PI3K blockade enhances the antitumor activity of eribulin in PIK3CA-mutant eribulin-resistant tumor xenografts

Eribulin is a recently approved microtubule-targeting agent (MTA) for the management of heavily pretreated metastatic breast cancer (BC) patients. Constitutive PI3K/Akt/mTOR survival pathway activation, either via mutational activation of the PI3K catalytic subunit (PIK3CA) or via inactivation of the tumor suppressor PTEN, may confer resistance to MTAs. Hence, we hypothesized that PI3K-pathway activation limits the antitumor activity of eribulin in HER2-negative BC and that PI3K inhibition enhances the efficacy of this chemotherapeutic agent.

The predictive value of PIK3CA mutation or PTEN loss towards eribulin response was interrogated in vitro, using a panel of fourteen HER2-negative BC cell lines, and in vivo using six tumor models from cell-line or patient-derived tumors. While PIK3CA mutation did not seem to be predictive in vitro, the PIK3CA-mutated xenograft models underwent tumor progression upon single-agent eribulin therapy (Table 1). In the absence of concomitant PIK3CA mutation, PTEN loss was neither predictive in vitro nor in vivo. Moreover, eribulin induced PI3K-pathway activation in tumor xenografts, a potential escape mechanism to MTA-therapy. To validate the negative predictive value of PIK3CA mutation, BC tumors from patients treated with eribulin in the neoadjuvant and in the metastatic setting are being queried, as the pharmacodynamic activation of the PI3K-pathway upon eribulin treatment.

Class I pan-PI3K (BKM120) or PI3K-a-specific (BYL719) inhibitors were used in vitro to block the PI3K-pathway concomitantly with eribulin treatment, resulting in enhanced antiproliferative and proapoptotic activity. Strikingly, in PIK3CA mutant xenograft models, while eribulin alone exhibited limited antitumor activity compared to PIK3CA-wild type models, co-administration of a PI3K inhibitor induced marked tumor regression (BKM120 data in Table 1, BYL719 data will be reported). Moreover, addition of the PI3K inhibitor at progression with eribulin single-agent also resulted in tumor regression. Of note, PIK3CA-wild type models also exhibited increased antitumor activity with the combined therapy compared to single-agent treatments. The precise mechanism by which the combination of eribulin and a PI3K-targeting agent results in tumor regression is currently under investigation, embracing both the induction of mitotic catastrophe in tumor cells and the regularization of the tumor vasculature.

These results support the clinical development of therapeutic regimens combining PI3K-inhibitors to the approved MTA eribulin and might be predictive of clinical benefit both in the PIK3CA-mutant and -wild type breast cancer population.

Table 1. Percentage change in tumor volume.StatusPIK3CA mutantPIK3CA mutant and PTEN-lowPTEN-lowWTModel/ TreatmentMCF7LPDX44CAL51MDA-MB-468PDX88PDX98Eribulin39 ± 9683 ± 51364 ± 127-47 ± 14-26 ± 34-36 ± 33BKM120501 ± 169116 ± 111119 ± 73-9 ± 23128 ± 3787 ± 112Eribulin + BKM120-70 ± 27-80 ± 1051 ± 46-75 ± 12-94 ± 5-65 ± 13Patient- (PDX) and cell line-derived tumor xenografts were treated with eribulin mesylate (0.1mg/kg, 3IW) and/or BKM120 (27.5 mg/kg, 6IW) for 26-31 days.. IW, in week.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-08-06.

Abstract P4-12-01: Molecular features and survival outcomes of the intrinsic subtypes of breast cancer based on HER2 gene amplification

Background: HER2-amplified (HER2+) breast cancer is biologically heterogeneous and all the intrinsic molecular subtypes (Luminal A, Luminal B, HER2-enriched and Basal-like) can be identified. However, the molecular and outcome differences of the intrinsic subtypes based on HER2 status have not been thoroughly studied. This is important since HER2 is considered an oncogene involved in the activation of various signal transduction pathways, as well as a biomarker of poor prognosis (in the absence of anti-HER2 targeting).

Methods: To compare molecular features between clinically HER2+ and HER2-negative tumors, we interrogated The Cancer Genome Atlas (TCGA) publicly available dataset of 825 primary breast cancers with at least one of following data types: mRNA expression (17,784 genes), protein expression (171 proteins and phospho-proteins), DNA methylation status (574 probes), miRNA expression (306 transcripts) and whole exome somatic mutations. Two-class unpaired Significant Analyses of Microarrays were used to identify significant biomarker associations with a False Discovery Rate of 0%. For survival associations, we interrogated the METABRIC DNA copy number/gene expression-based dataset (Curtis et al. Nature) composed of 1,971 primary breast tumors with long-term clinical follow-up (and no adjuvant anti-HER2 therapy). Multivariable Cox models were used to test the prognostic significance of each variable. The research based 50-gene PAM50 model was used to classify tumors into the different intrinsic subtypes.

Results: In both datasets combined (n = 2,225), HER2+ disease showed an enrichment for HER2-enriched tumors (47.0% vs. 7.1%) and a decrease in Luminal A tumors (7.3% vs. 39.0%) compared to HER2-negative disease (p<0.001). In the TCGA dataset, the percentage of HER2+ tumors within HER2-enriched (n = 55), Luminal B (n = 122), Luminal A (n = 223) and Basal-like (n = 95) subtypes were 70.9%, 16.4%, 6.3% and 2.7%, respectively. Within each intrinsic subtype, only between 13 to 44 genes (0.07% to 0.25% of all genes evaluated) were found more expressed in HER2+ tumors compared to HER2-negative tumors. The vast majority (77.5%) of these significant genes are located on the 17q12 chromosomal amplicon, such as HER2 and GRB7. Interestingly, luminal- or proliferation-related genes were not found differentially expressed when all HER2+ tumors were compared against all HER2-negative tumors within a given subtype. Similarly, only 6 to 7 proteins (ERBB2, pERBB2, EGFR, EGFR_pY1068, EGFR_pY992, RPS6KB1 and ACACA), mostly located in the 17q12 amplicon (except EGFR), were found differentially expressed between HER2+ and HER2-negative tumors within a given subtype. Minimal changes were also noted when DNA methylation patterns, miRNA gene expression and somatic mutations were evaluated. Finally, no additional prognostic value was observed with the addition of HER2 status to intrinsic subtype.

Conclusions: When the intrinsic subtypes are taken into account, HER2 amplification does not translate into large changes in the activation of downstream signaling pathways or worse patient survival outcomes. These results also suggest that the potential responses to anti-HER2 therapy on HER2-amplified tumor cells depend in part upon their intrinsic tumor profile.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-12-01.

Abstract OT1-2-04: PAM50 HER2-enriched (HER2E) phenotype as a predictor of early-response to neoadjuvant lapatinib plus trastuzumab in stage I to IIIA HER2-positive breast cancer

Background: The efficacy of trastuzumab in different regimens and settings has been well established, including its benefit as neoadjuvant therapy for early HER2-positive disease. Combinations of two different anti-HER2 therapies without chemotherapy have generated great expectations. However, it is unclear which group of patients benefits the most from this strategy. Within HER2-positive breast cancer, the PAM50 assay identifies a HER2-Enriched (HER2-E) intrinsic subtype characterized by high activation of the EGFR/HER2 pathway and low expression of luminal-related genes, and therefore should obtain the greatest benefit from anti-HER2 therapy.

Trial Design: This non-randomized, open-label, multicentric phase II translational research study will evaluate the ability of the PAM50 HER2-E subtype to predict pathological complete response (pCR) to dual HER2 blockade with lapatinib and trastuzumab for a total of 18 weeks. Patients with hormone receptor (HR)-positive disease will also receive endocrine therapy (letrozol or tamoxifen).

Eligibility Criteria: Untreated, histologically confirmed invasive breast carcinoma eligible for definitive surgery (stage I-IIIA), HER2-positive invasive breast cancer by central assessment, premenopausal or postmenopausal, ECOG performance status of 0 or 1, adequate organ function and baseline LVEF >50% measured by echocardiography or MUGA scan.

Specific Aims: The primary objective is to evaluate the ability of the PAM50 assay to predict pCR in the breast at the time of surgery. Secondary objectives are to (1) assess the correlation of HER2-E with pCR in the breast and axilla, (2) assess the correlation of HER2-E with Residual Cancer Burden (RCB) (3) evaluate the gene expression changes from Day 0 to Day 14 and the correlations with Ki67-IHC at Day 14, (4), identify additional gene expression signatures predictive of pCR, and (5) evaluate safety and tolerability.

Statistical Methods: The statistical plan is based on the assumption that breast pCR rate will be 35.0% for HER2-E tumors and 8.0% for non-HER2E. The study will have a 95% power with a significance level of 5% (two-sided) and an assumed drop-out rate of 15%. Biomarker Analyses: Baseline, 14-day treated and post-treatment (surgical) formalin–fixed, paraffin–embedded tissues will be obtained. The expression of 547 genes will be explored with the nCounter platform. Subtype will be identified using the PAM50 predictor (Parker et al. J Clin Oncol 2009). Ki-67-IHC will also be evaluated on pre-treatment and Day-14 samples.

Target Accrual: 150 patients with a maximum of 75 HR-positive patients across Spain and Portugal. Patient enrollment will begin in July 2013.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT1-2-04.

Removal of groundwater arsenic using a household filter with iron spikes and stainless steel

Arsenic (As) in groundwater for domestic use poses a worldwide threat to public health, most notably in rural areas. The aims of this study were: first, determine groundwater composition in a mining area in central Mexico (Huautla); second, assess As exposure through human groundwater consumption and; third, develop and test a household filter to obtain drinking water for these rural communities. From the 17th century through the 1990s, mines in the area produced Ag-galena and sphalerite from volcanic rock. Groundwater flooded the mines when they were abandoned due to low silver prices. Local households now use the water to meet domestic needs. Water from the mines was found to have high As content (0.04-0.26 mg L(-1)) and Fe, Mn, Pb and Cd were also above Mexican drinking water standards and WHO guidelines. All the population in the Huautla community was exposed to the metalloid through water used in food preparation. The best As removal was obtained with a filter using oxidized commercial fiber (HCl 2N as oxidant). Concentrations in the effluent were below Mexican drinking water standards (0.025 mg As L(-1) water) during the 105-day (2520 h) filter operation, with a maximum As removal efficiency of 95.4%. The household filter was simple, low-cost and may be very attractive for As removal in rural areas in developing countries.