Abstract P5-21-23: Evaluation of the drug interaction potential of palbociclib and exemestane – Results from the PEARL pharmacokinetic sub-Study

Background: Palbociclib (PAL) is an oral cyclin-dependent kinase (CDK) 4/6 inhibitor that is under investigation in multiple oncologic clinical trials and is currently approved for use in combination with aromatase inhibitors (AIs) or fulvestrant (FUL) in patients with hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2–) advanced breast cancer (BC).

The PEARL Study is an ongoing international, open label, controlled, randomized Phase 3 study comparing the efficacy and safety of PAL in combination with endocrine therapy (exemestane [EXE] or FUL) versus capecitabine in postmenopausal women with HR+/ HER2– metastatic BC whose disease progressed on AIs. A secondary objective of the study was to evaluate the pharmacokinetics (PK) of PAL (125mg QD, 3 weeks on/1 week off) and EXE (25mg QD, continuously) when coadministered. This is the first study to investigate the drug-drug interaction (DDI) potential of the combination of PAL and the AI EXE.

Methods: Patients (pts) randomized to the PAL+EXE arm of the PEARL Study in seven selected sites had the option of participating in the PK sub-study. Those who enrolled in the PK sub-study received EXE alone in a 7-day lead-in period immediately prior to Cycle 1 Day 1, when both drugs were coadministered on their standard dosing regimens. Sub-study pts were to have 2 pre-dose plasma PK samples drawn at steady-state (ss) during the lead-in period ("EXE Alone") for EXE determination, and 2 ss PK samples drawn for EXE and PAL determination (2 per analyte) during coadministration ("PAL+EXE"). Plasma concentrations of PAL and EXE were measured using validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. The withinpatient mean concentration of the PK samples which met ss acceptance criteria (WPM-Ctrough) for each analyte were generated for each treatment period as the input for DDI analyses.

To assess the effect of coadministration of PAL on EXE PK, the WPM-Ctrough of EXE was compared within patients between the "PAL+EXE" (Test) and "EXE Alone" (Reference) treatment periods using a one-way analysis of variance (ANOVA) model with treatment as a fixed effect and patient as a random effect. To assess the effect of coadministration of EXE on PAL PK, the WPM-Ctrough of PAL was compared between the "PAL+EXE" period (Test) and historical data (Reference) using an ANOVA model. Analysis of covariance (ANCOVA) models were used to assess the impact of demographic differences between analysis populations in covariates known to impact PAL PK on the ANOVA model conclusions.

Results: A total of 26 pts randomized to the PAL+EXE arm were enrolled in the PK sub-study and had PK samples analysed, of which 23 meet ss acceptance criteria. The ratio of the adjusted geometric means for EXE WPM-Ctrough was 106.9% (90%CI: 82.4-138.8), when EXE was administered with PAL, compared with its administration alone. Likewise, the models to assess potential for EXE to perpetrate DDI on PAL PK showed ratios of adjusted geometric means of 102.4% (90%CI: 82.0-127.9) and 111.6% (90%CI: 90.3137.8), when adjusted for covariates.

Conclusion: The PK data indicate a lack of a clinically meaningful DDI between PAL and EXE when the 2 drugs are coadministered.

Sponsor: GEICAM

Citation Format: Martín M, Hoffman J, Ruiz-Borrego M, Muñoz M, Calvo L, Crownover P, García-Sáenz JA, Alba E, Wang D, Thallinger C, Stradella A, Montaño Á, Adamo B, Antolín S, Moreno-Antón F, Falo C, Ruiz V, Martín N, Caballero R, Carrasco E, Gil-Gil M. Evaluation of the drug interaction potential of palbociclib and exemestane – Results from the PEARL pharmacokinetic sub-Study [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 P5-21-23.

Abstract OT1-01-04: VENTANA (SOLTI-1501): Oral metronomic vinorelbine combined with endocrine therapy in luminal/HER2-negative early breast cancer: A window of opportunity trial

BACKGROUND

The CDK4/6 inhibitor palbociclib, in combination with endocrine therapy (ET), has been approved for patients (pts) with HR+/HER2- metastatic breast cancer (BC), suggesting that inhibition of the cell cycle in combination with ET is a strategy to keep exploring. In this context, vinorelbine (VNB) inhibits chromosome segregation during mitosis and blocks cells at G2/M. Interestingly, several metronomic schedules of VNB are being used in the clinical setting, a strategy that might not only affect cell-cycle but also aims to target tumor angiogenesis.

VENTANA is a “window-of-opportunity” trial designed to explore whether, similarly to CDK4/6 and mTOR inhibitors, oral metronomic VNB in combination with endocrine therapy induces a superior anti-proliferative effect than ET alone, as suggested by preclinical and clinical studies. We believe that a biological synergy of the combined treatment could open the door to include this treatment strategy in pts with BC as an alternative to CDK4/6 inhibitors.

METHODS

VENTANA is a phase 0 multicenter, three-arm, randomized clinical trial of oral metronomic VNB and letrozole (LET) versus either treatment alone in postmenopausal women with newly diagnosed, untreated HR+ and HER2-, stage I-III operable BC. Other eligibility criteria include primary tumor size ≥1 cm (cT1-3) and N0-1, ECOG PS 0-1 and evaluable diagnostic tumor sample. Pts are randomized (1:1:1) to receive LET 2.5mg daily, oral VNB 50mg 3 days a week, or LET 2.5mg daily and oral VNB 50mg 3 times a week. After 3 weeks of treatment, pts will undergo surgery, and both pre-treatment and post-treatment surgical samples will be analyzed for gene expression. Primary objective is to test if oral metronomic VNB and LET induce a superior anti-proliferative effect than either drug alone in pts with early BC defined as Luminal by PAM50. This will be evaluated by the expression of 11 proliferative genes contained in the PAM50 subtype predictor (BIRC5, CCNB1, CDC20, CDCA1, CEP55, KNTC2, MKI67, PTTG1, RRM2, TYMS and UBE2C) as surrogate signature biomarker of its anticancer activity.

VENTANA is a proof-of-concept study to describe the change in the expression of a proliferation-related gene signature in all 3 treatment arms. Changes in the proliferation signature will be determined by following formula: Mean suppression of proliferation signature score = 100 − [geometric mean (post treatment proliferation score / pre-treatment proliferation score · 100)]. By evaluating other BC-related gene signatures (560 genes), the antiangiogenic and immunogenic potential of the treatment arms will also be compared and genes regulated in a treatment-specific manner identified. All analyses will be performed within the different PAM50-defined subtypes (Luminal, Luminal A or Luminal B).

As the primary endpoint is continuous and there are no previous data to make assumptions about the degree of suppression of these genes, the sample size has not been determined by statistical calculations. A sample size of 20 pts per arm is considered appropriate to support our hypothesis. The targeted accrual of 60 pts will be enrolled in 10 sites across Spain (EudraCT Number 2015-004714-24).

Citation Format: Adamo B, Vidal M, Gomez Pardo P, Zaragoza K, Ciruelos E, Virizuela JA, Blanch Tormo S, Pérez-Fidalgo JA, Murillo L, Lopez-Gonzalez A, Amillano Parraga K, Martinez Jañez N, Gonzàlez Farré X, Prat A. VENTANA (SOLTI-1501): Oral metronomic vinorelbine combined with endocrine therapy in luminal/HER2-negative early breast cancer: A window of opportunity trial [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 OT1-01-04.

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 P2-08-16: Prognostic and predictive abilities of intrinsic subtype in hormone receptor-positive metastatic breast cancer from the EGF30008 phase III clinical trial

Background

Combination of letrozole and lapatinib improved progression-free survival (PFS) compared with letrozole and placebo in patients with hormone receptor-positive (HR+)/HER2+ metastatic breast cancer (MBC), but not HR+/HER2-negative (HER2-) disease (JCO 2009). However, HR+ disease is clinically and biologically heterogeneous with all intrinsic molecular subtypes (Luminal A, Luminal B, HER2-enriched [HER2E] and Basal-like) identified. Here, we tested retrospectively the prognostic and predictive ability of intrinsic subtype in tumor samples of the EGF30008 trial.

Methods

Expression profiling from FFPE tumor tissues was performed on the nCounter platform. Tumors were classified into each intrinsic subtype using the research-based PAM50 classifier (JCO 2009). Cox proportional hazard models for PFS and overall survival (OS) were used to generate point estimates of hazard ratios (HR) and corresponding 95% confidence intervals (CIs). Changes in likelihood ratio χ2 values were used to measure and compare the relative amount of information of each variable. Variables evaluated were: age, prior endocrine therapy, presence of visceral disease, number of metastatic sites, performance status, clinical HER2 status, and treatment. To determine whether the intrinsic subtypes were predictive of lapatinib benefit, we tested the interaction term of subtype by treatment arm in a Cox model that also included the main effects. Kaplan-Meier plots were used to depict the proportion of patients free from progression as a function of time.

Results

Tumor samples from 821 patients (63.8%) were profiled (85.7% primary and 14.3% metastatic tumor samples). Clinical-pathological features of this patient subset were well balanced compared with the original set. Within the entire cohort, all subtypes were identified: Luminal A (46.5%); Luminal B (29.7%); HER2E (7.4%); Basal-like (3.4%) and normal-like (12.9%). Within HER2+ disease, 28.6% of samples were HER2E. Intrinsic subtype was found the strongest prognostic factor independently associated with PFS and OS in all patients, and in patientswith HER2-negative or HER2+ disease (P<0.0001). Median PFS and OS for each subtype within clinically HER2-negative disease were: Luminal A (16.85 and 45.0 months), Luminal B (10.97 and 37.0 months), HER2E (4.67 and 16.0 months) and Basal-like (4.14 and 23.0 months). Within clinically HER2-negative disease (n=644), 16 patients (2.5%) had HER2E disease. Patients with HER2-/HER2E disease benefited from lapatinib (6.5 vs 2.6 months; PFS HR =0.24, 95% CI: 0.07-0.86; P=0.019; HER2E vs not treatment interaction P=0.016). Finally, intrinsic subtype was not predictive of benefit from lapatinib within HER2+ disease.

Conclusions

HR-positive disease is biologically heterogeneous and intrinsic subtypes are strongly prognostic in a first-line MBC setting. HR+/HER2- disease with a HER2E profile may benefit from lapatinib. The clinical value of intrinsic subtyping in HR+ MBC warrants further investigation, but patients with Luminal A/HER2-negative MBC disease might be good candidates for letrozole monotherapy in the first-line setting regardless of visceral disease and number of metastases.

Citation Format: Prat A, Cheang MCU, Galván P, Nuciforo P, Paré L, Adamo B, Viladot M, Press MF, Gagnon R, Ellis C, Johnston S. Prognostic and predictive abilities of intrinsic subtype in hormone receptor-positive metastatic breast cancer from the EGF30008 phase III clinical trial. [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 P2-08-16.

Predicting response and survival in chemotherapy-treated triple-negative breast cancer

BACKGROUND

In this study, we evaluated the ability of gene expression profiles to predict chemotherapy response and survival in triple-negative breast cancer (TNBC).

METHODS

Gene expression and clinical-pathological data were evaluated in five independent cohorts, including three randomised clinical trials for a total of 1055 patients with TNBC, basal-like disease (BLBC) or both. Previously defined intrinsic molecular subtype and a proliferation signature were determined and tested. Each signature was tested using multivariable logistic regression models (for pCR (pathological complete response)) and Cox models (for survival). Within TNBC, interactions between each signature and the basal-like subtype (vs other subtypes) for predicting either pCR or survival were investigated.

RESULTS

Within TNBC, all intrinsic subtypes were identified but BLBC predominated (55-81%). Significant associations between genomic signatures and response and survival after chemotherapy were only identified within BLBC and not within TNBC as a whole. In particular, high expression of a previously identified proliferation signature, or low expression of the luminal A signature, was found independently associated with pCR and improved survival following chemotherapy across different cohorts. Significant interaction tests were only obtained between each signature and the BLBC subtype for prediction of chemotherapy response or survival.

CONCLUSIONS

The proliferation signature predicts response and improved survival after chemotherapy, but only within BLBC. This highlights the clinical implications of TNBC heterogeneity, and suggests that future clinical trials focused on this phenotypic subtype should consider stratifying patients as having BLBC or not.

Phase I/IIa study evaluating the safety, efficacy, pharmacokinetics, and pharmacodynamics of lucitanib in advanced solid tumors

BACKGROUND

Lucitanib is a potent, oral inhibitor fibroblast growth factor receptor types 1 and 2 (FGFR), vascular endothelial growth factor receptor types 1, 2, and 3 (VEGFR), platelet-derived growth factor receptor types α and β (PGFRα/β), which are essential kinases for tumor growth, survival, migration, and angiogenesis. Several tumor types, including breast carcinoma, demonstrate amplification of fibroblast growth factor (FGF)-related genes. There are no approved drugs for molecularly defined FGF-aberrant (FGFR1- or FGF3/4/19-amplified) tumors.

METHODS

This open-label phase I/IIa study involved a dose-escalation phase to determine maximum tolerated dose (MTD), recommended dose (RD), and pharmacokinetics of lucitanib in patients with advanced solid tumors, followed by a dose-expansion phase to obtain preliminary evidence of efficacy in patients who could potentially benefit from treatment (i.e. with tumors harboring FGF-aberrant pathway or considered angiogenesis-sensitive).

RESULTS

Doses from 5 to 30 mg were evaluated with dose-limiting toxic effects dominated by vascular endothelial growth factor (VEGF) inhibition-related toxic effects at the 30 mg dose level (one case of grade 4 depressed level of consciousness and two cases of grade 3 thrombotic microangiopathy). The most common adverse events (all grades, all cohorts) were hypertension (91%), asthenia (42%), and proteinuria (57%). Exposure increased with dose and t½ was 31-40 h, suitable for once daily administration. Seventy-six patients were included. All but one had stage IV; 42% had >3 lines of previous chemotherapy. Sixty-four patients were assessable for response; 58 had measurable disease. Clinical activity was observed at all doses tested with durable Response Evaluation Criteria In Solid Tumors (RECIST) partial responses in a variety of tumor types. In the angiogenesis-sensitive group, objective RECIST response rate (complete response + partial response) was 26% (7 of 27) and progression-free survival (PFS) was 25 weeks. In assessable FGF-aberrant breast cancer patients, 50% (6 of 12) achieved RECIST partial response with a median PFS of 40.4 weeks for all treated patients.

CONCLUSION

Lucitanib has promising efficacy and a manageable side-effect profile. The spectrum of activity observed demonstrates clinical benefit in both FGF-aberrant and angiogenesis-sensitive populations. A comprehensive phase II program is planned.

Proton pump inhibitors and functional decline in older adults discharged from acute care hospitals

OBJECTIVES

To investigate the relationship between use of proton pump inhibitors (PPIs) and incident dependency in older adults discharged from acute care hospitals.

DESIGN

Prospective observational study.

SETTING

Eleven geriatric and internal medicine acute care wards located throughout Italy.

PARTICIPANTS

Individuals (mean age 79.2 ± 5.5) who were not completely dependent at the time of discharge from participating wards (N = 401).

MEASUREMENTS

The outcome of interest was the loss of at least one basic activity of daily living (ADL) from discharge to the end of follow-up (12 months). The relationship between PPI use and functional decline was investigated using logistic regression analysis before and after propensity score matching.

RESULTS

Use of PPIs was significantly associated with functional decline before (odds ratio (OR) = 1.75, 95% confidence interval (CI) = 1.17-2.60) and after propensity score matching (OR = 2.44; 95% CI = 1.36-4.41). Other predictors of functional decline were hypoalbuminemia (OR = 3.10, 95% CI = 1.36-7.10 before matching, OR = 2.81, 95% CI = 1.09-7.77 after matching) and cognitive impairment (OR = 4.08, 95% CI = 1.63-10.2 before matching, OR = 6.35, 95% CI = 1.70-24.0 after matching).

CONCLUSION

Use of PPIs is associated with functional decline during 12 months of follow-up in older adults discharged from acute care hospitals.

Genomic aberrations in the FGFR pathway: opportunities for targeted therapies in solid tumors

The fibroblast growth factor receptor (FGFR) cascade plays crucial roles in tumor cell proliferation, angiogenesis, migration and survival. Accumulating evidence suggests that in some tumor types, FGFRs are bona fide oncogenes to which cancer cells are addicted. Because FGFR inhibition can reduce proliferation and induce cell death in a variety of in vitro and in vivo tumor models harboring FGFR aberrations, a growing number of research groups have selected FGFRs as targets for anticancer drug development. Multikinase FGFR/vascular endothelial growth factor receptor (VEGFR) inhibitors have shown promising activity in breast cancer patients with FGFR1 and/or FGF3 amplification. Early clinical trials with selective FGFR inhibitors, which may overcome the toxicity constraints raised by multitarget kinase inhibition, are recruiting patients with known FGFR(1-4) status based on genomic screens. Preliminary signs of antitumor activity have been demonstrated in some tumor types, including squamous cell lung carcinomas. Rational combination of targeted therapies is expected to further increase the efficacy of selective FGFR inhibitors. Herein, we discuss unsolved questions in the clinical development of these agents and suggest guidelines for management of hyperphosphatemia, a class-specific mechanism-based toxicity. In addition, we propose standardized definitions for FGFR1 and FGFR2 gene amplification based on in situ hybridization methods. Extended access to next-generation sequencing platforms will facilitate the identification of diseases in which somatic FGFR(1-4) mutations, amplifications and fusions are potentially driving cancer cell viability, further strengthening the role of FGFR signaling in cancer biology and providing more possibilities for the therapeutic application of FGFR inhibitors.

Abstract P6-11-06: Efficacy of carboplatin alone or with ABT888 in an intracranial murine model of BRCA-mutated, basal-like, triple negative breast cancer (TNBC)

Background: TNBC frequently spreads to the central nervous system and is associated with poor outcome. Twenty percent of women with TNBC harbor a BRCA mutation(mut). BRCA dysfunction impairs repair of DNA double-strand breaks by homologous recombination(HR) and sensitizes tumor cells to DNA-damaging cytotoxic agents. Emerging evidence suggests that TNBC responds to platinums(Pt) and drugs potentiating efficiency of DNA damage, such as PARP inhibitors; combination therapy may enhance DNA damage and induce additional cytotoxicity. Recognizing that Pt and many PARP inhibitors penetrate the blood brain barrier(BBB), we evaluated the efficacy of carboplatin(Carbo) alone and with the PARP inhibitor, ABT888(ABT), in murine intracranial(IC) TNBC models characterized by BRCA status.

Methods: Athymic (nu/nu) mice(10wks) were inoculated intracerebrally with 2×105 SUM149(BRCA1mut, pTEN-; basal) cells expressing luciferase. On day14, tumor-bearing mice began treatment with Control(PBS IP weekly), Carbo(50mg/kg IP weekly) and ABT(25mg/kg OG daily) as single agents, or in combination. Survival and IC tumor growth via bioluminescence were compared by treatment. Net PAR levels(PARpg/ml/100ug total protein) were measured in IC tumor tissue(ELISA pharmacodynamic assay) 14days post ABT. Presence of Pt DNA adducts was measured in IC tumor tissue following Carbo+/-ABT by ICP-MS. Survival and IC tumor growth via bioluminescence of the MDA-MB468(BRCAnon-mut, pTEN-; basal) IC model treated with the same regimens were assessed.

Results: In the SUM149 TNBC IC model, Carbo+/-ABT resulted in improved survival compared to control (Table). Single agent ABT did not yield a survival benefit over control. Combination Carbo/ABT showed a modest advantage in survival compared to Carbo alone (p = 0.28). IC tumor mean net PAR levels ± SEM were significantly lower in ABT-treated animals compared to control (182.1 ± 91.3 vs 825.7 ± 174.7, p = 0.0043). Addition of ABT did not impair Carbo BBB penetration; Mean ± SEM Pt-DNA adducts were detected in IC tumor after administration of Carbo and Carbo/ABT (0.91±0.13 and 1.46±0.03 pgPt/ugDNA). In contrast to the SUM149 IC model, there was no survival improvement for the MDA-MB468 IC model treated with Carbo+/-ABT compared to control(p = 0.81).

 SUM149(BRCA1mut)MDA-MB468(BRCA1non-mut)TreatmentNMedian Survival (95%CI), dayspValueNMedian Survival (95%CI), daysControl1736(34-40)N/A535(29-57)ABT1039(30-46)p = 0.22544(33-57)Carbo1658(47-67)p<.0001537(33-54)Carbo/ABT1764(59-75)p<.0001537(33-50)

Conclusions: This study shows Pt analogues, specifically Carbo, represent a promising treatment strategy for TNBC brain metastases with BRCA dysfunction. Improved survival relies on the ability of Pt analogues to penetrate the BBB and higher cytotoxicity may be due to compromised HR in TNBC as compared to models with functional BRCA. Although inhibitory activity of ABT was detected in IC tumors, we did not observe a significant additive effect of ABT to Carbo when used in combination. Confirmatory studies in additional IC TNBC models, including claudin-low subtype, as well as mechanistic studies evaluating DNA damage via γH2AX foci and differential gene expression in response to treatment are ongoing.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-11-06.

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.

Hematopoietic progenitor cells (HPCs) in node-negative invasive breast carcinomas: Immunohistochemical analysis and clinico-pathological correlations

Using immunohistochemistry, we investigated 603 negative lymph nodes from 51 patients affected by invasive breast cancer (BC) to recognize bone marrow-derived hematopoietic progenitor cells (HPCs). HPC aggregates, revealed by CD34, CD133, VEGFR1, and CD117 antisera, were determined by an intensity-distribution score (ID). Cases with an ID-score >3 at least for one marker were considered to strongly express HPCs. Twenty-five of 51 (49%) high expressor patients were identified by CD34 antiserum, while 24/51 (47.1%), 17/51 (33.3%), and 15/51 (29.4%) were identified by CD117, CD133, and VEGFR1, respectively. No significant relationships were found between HPCs status and histotype, tumor grade, stage, and hormone receptors, as determined at the moment of the first diagnosis. A significant correlation was recorded for Ki-67 values, as well as for death from invasive BC. No statistical significance was achieved regarding HER2 status, although a tendency toward a statistically significant P value was obtained. A significant relationship (P<0.001) was found between high expressors of HPC and progression of disease, documented by the development of distant metastases. An equivalent P value was ascertained for osseous localizations, with a lesser value in other metastatic sites. Regarding the appearance of distant metastases, the greatest efficiency value was obtained by CD133 (85.7%). Overall survival (OS) and distant metastases-free survival (DMFS) revealed a high statistical significance for HPC expression, Ki-67 values, and HER2 status. By multivariate analysis, HPC expression and Ki-67 values emerged as the higher independent prognostic variables in the analysis of DMFS and OS, respectively.

Abstract P1-14-01: Phosphatidylinositol 3-Kinase (PI3K) Pathway Activation in Breast Cancer Brain Metastases

Background:

Brain metastases (BM) are a devastating consequence of advanced breast cancer (BC) for which novel, targeted therapies are urgently needed. The PI3K pathway plays a critical role in the initiation and progression of BC. Alterations in this pathway are implicated in approximately 50% of BC. The role of PI3K activation in BCBM has yet to be explored. Material and Methods:

Under IRB approval (UNC and Duke), we established a clinically-annotated tumor bank including 54 BCBM and 15 matched primary BC. Activation of the PI3K pathway including pAKT, pS6K, and PTEN was assessed via immunohistochemistry (IHC, score 0-3+). BC subtype was assigned by IHC: HR+ (hormone receptor, ER+ and/or PR+)/HER2-, triple-negative (TN; ER-/PR-/HER2-), and HR +or-/HER2+. Overall survival (OS), recurrence patterns and survival following BM was evaluated by the Kaplan-Meier method and compared by the log-rank test.

Results:

Median age was 48 years (range 26-72). Sixty-eight percent of patients (pts) were Caucasian, 30% African-American, and 2% other ethnicities. At median follow-up of 5.9 years (yrs), 70% (38/54) of pts had died. BC subtype was confirmed among 47 pts: 30% (14/47) HR+/HER2-, 45% (21/47) TN and 25% (12/47) HR +or-/HER2+. Subtype concordance between primary BC and BM was 89% (8/9). High expression (IHC score 2-3+) of pAKT and pS6K was observed in 50% (27/54) and 72% (38/54) of the BCBM, respectively. Low expression of PTEN (IHC score 0-1) was observed in 31% (17/54) of BCBM. Concordance of PI3K biomarkers between primary BC and matched BCBM was 47% (7/15), 40% (6/15) and 80% (12/15) for pAKT, pS6K and PTEN, respectively. Both gain and loss of protein expression between primary BC and BCBM was observed in each biomarker evaluated. No significant correlation between BC subtypes and activation status of the PI3K pathway (IHC score 0-1 vs. 2-3+) was observed for pAKT, pS6K or PTEN. Median OS was 7.09 yrs (3.52, 9.21), 4.27 yrs (95% CI 1.84, 5.18), and not reached (NR) for HR+/HER2-, TN and HR +or-/HER2+, respectively (p=0.009). Median OS after BCBM diagnosis was 1.54 yrs (0.27, 2.45), 0.91 yrs (0.51, 1.49) and NR for HR+/HER2-, TN and HR +or-/HER2+, respectively (p=0.0003). Expression (0-1+ vs. 2-3+) of pAKT and pS6K in BCBM was not predictive of OS, time to BCBM recurrence or survival after BCBM (all P&gt;0.1). Although not predictive of inferior survival following BCBM (1.2 vs. 1.5 yrs, p=0.7), low expression (0-1+ vs. 2-3+) of PTEN in BCBM predicted for inferior OS from primary BC diagnosis (5.1 vs. 6.3 yrs, p=0.03) and shorter time to BCBM (2.5 vs. 3.4 yrs, p=0.008). Conclusions:

The PI3K pathway is active in most BCBM regardless of subtype. Considerable discordance exists between PI3K pathway biomarkers in the primary BC and BCBM from the same patient. Low expression of PTEN in BCBM may be prognostic. Given that small molecule inhibitors of the PI3K pathway in clinical development cross the blood brain barrier, inhibition of the PI3K pathway represents a promising therapeutic strategy for a group of patients whose prognosis is poor and for whom systemic therapies are limited.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-14-01.

Preliminary Study of Pre-Metastatic Niche (PMN) in Nonmetastatic Nodes for the Assessment of Metastasis Risk in Breast Cancer (BC)

Bone marrow-derived hematopoietic progenitor cells (HPCs) seem to participate in early spread of cancer cells by forming a peculiar and highly organized micro-environment called PMN. Identifying such HPCs in the PMNs is emerging as a key step in assessing risk of metastasis.In this preliminary study we analysed 294 axillar nodes (271 pN0 and 23 pN1a) obtained from 30 pts undergone surgery for breast ductal invasive carcinoma in the period 1998-2000.Pts mean age was 61.2 years (range 45-79); 9 pts (30%) were premenopausal and 21 (70%) postmenopausal; 13 pts (43.3%) had ER+, 10 (33.3%) PR+; MIB1 was ≤ 25% in 22 pts (73.3%), &gt;25% in 6 (20%), unknown in 2 pts. After a median follow-up of 81.27 mos (range 12–136), 14 pts are disease-free, 9 pts dead of metastatic disease. Involved sites were: 1 loco-regional, 7 bone, 3 lung, 4 liver, 1 brain.Samples were fixed in 10% neutral buffered formalin for 12-72 hrs and included in paraffin at 56°C; 4 mm thick sections were pre-treated in microwave owen in 10 mM citric acid, pH 6.0 and incubated overnight with the following poly/mono-clonal antisera: VEGF-R1 (Santa Cruz Biothechnology 1:400),CD 133(Abgent 1:80),CD 117 (DAKO 1:500),CD-34 (DAKO 1:50).Clusters of immunoreactive cells were evident with CD 117 and CD 34 in all nodes.A different degree of immunopositivity was found with VEGR-R1 and CD 133 antibodies for different sites of metastasis; in particular, the cases spread in lungs, liver and central nervous system were more immunoreactive, compared to those with bone localization. All nodes classified as pN1a showed no immunoreactivity.The prognostic significance of HPCs in PMN needs to be further investigated, especially in node-negative BCs. The immunomorphologic aspect of the lymph node microenvironment could have significant clinical implications, in order to optimize BC therapeutic strategies.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6024.