Abstract P1-07-09: Retrospective cohort study of patients (pts) diagnosed with breast cancer (BC) <40 yrs: 2000 to 2015⟨

Background

Young women (<40 yrs) with breast cancer (YWBC) account for 7-12% of BC diagnoses. BC is the leading cause of cancer death in this group (G). Age-specific data on outcome and appropriate treatment (Rx) are lacking. YWBC appear to have more biologically aggressive subtypes and a higher risk of relapse and death. We studied the clinico-pathological (ClinPath) characteristics in YWBC, examining how outcomes/Rx have evolved.

Methods

YWBC were identified from pathology databases at 2 tertiary centers. Pts were divided into 2 cohorts: BC diagnoses from 2000-2007 (G1) and 2008-2015 (G2). ClinPath and Rx data were retrieved from clinical, radiology and histology databases. Statistical analysis was performed using SPSS.

Results

We identified 347 pts. Tumor features are shown in Table I. Median age is 36 (23-39). By histology, 90.8% (n=315) had invasive ductal carcinoma, 53.1% (n=181) had Grade III BC and 56.3% (n=171) had lymphovascular invasion. Pregnancy-associated BC occurred in 10.7% (n=34). Mastectomy (MX) was performed in 53% (n=176) and axillary lymph node clearance (ALNC) in 63.8% (n=192 [G1: 84.3% vs. G2: 48.6%, p<0.001]).

Table 1Tumor features Group 1 (n=149)Group 2 (n=198)Total (n=347)p-valueMedian tumor size (mm) 252222.5p=0.115Node positivity 88 (60.3%)100(51.5%)188 (55.3%)p=0.109Median node count 4 (1-44)1 (1-30)2 (1-44)p<0.001StageI  99(29%)  II  148 (43.3%)  III  70 (20.5%)  IV  23(7.3%) Biomarker status*ER+/HER2-76 (53.1%)120 (60.6%)196 (56%)p=0.086 HER2+41 (28.7%)45 (22.8%)86 (27%)p=0.031 Triple negative (TN)26 (18.2%)33 (16.8%)59 (17%)p=0.291* Missing data n=6

Rx characteristics are shown in Table 2. 85 pts received neo-adjuvant therapy (NAT); 48.3% (n=41) ER+/HER2-, 27% (n=23) HER2+ and 24.7% (n=21) TNBC. Pts receiving NAT in G2 trended towards improved pCR rate (G2: 24.6% vs G1: 8.3%, p=0.057). Endocrine Rx alone was received by 9.8% (n=22); 13.6% (n=18) in G2 vs 4.3% (n=4) in G1. OncotypeDx(ODx) was used in 23 pts (14.9%) (median score 17), 1 had a DR (ODx Score = 18).

Table 2Tx characteristics n=347 Chemotherapy Total300(86.4%)  NAT85 (28.3%)Pathological Complete Response (pCR)* pCR (n=16, 19.8%)No pCR (n=65, 80.2%) ER+/HER2-18.8%(n=3)53.9% (n=35) HER2+/ER+18.8%(n=3)13.8% (n=9) HER2+/ER-31.2% (n=5)9.2% (n=6) TNBC31.2%(n=5)23.1%(n=15)Local relapse 1 (6.2%)1(1.5%)Distant relapse (DR) 022(33.8%)*Data incomplete n=4

DR occurred in 50 pts (16%), including 13 (20.3%) HER2+ pts. Of note, 92.3% (n=12) of these were in G1. Relapse rates (RR) in TN and ER+/HER- pts were 19.6% (n=11) and 13.7% (n=26) respectively. There was a higher RR in G1 (34.8% vs 11.4%, p<0.001). Overall survival in pts with stage IV dx was 32 mos in G1 and 48 mos in G2.

Conclusion

In line with existing data, locally advanced dx is more prevalent in YWBC. MX and ALNC rates were high and most received multimodal Rx. The extent of axillary surgery declined. Pts in G2 had lower volume BC at diagnosis suggesting increasing awareness. TN and HER2+ subtypes accounted for a slightly higher proportion of BC cases. Pts with PCR had better outcomes. Only 16% relapsed with metastatic dx. The impact of HER2 Rx is highlighted by reduced RR in HER2+ G2 pts. Outcomes were unchanged in pts with ER+/HER2- and TNBC. These remain a priority for future research.

Citation Format: Greally M, Kielty J, Das G, Malouf C, O'Riordan L, Coleman N, Quinn C, McDermott E, Gullo G, Kelly C, Crown J, Prichard R, Walshe J. Retrospective cohort study of patients (pts) diagnosed with breast cancer (BC) <40 yrs: 2000 to 2015⟨. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-07-09.

Abstract P6-03-09: Genetic polymorphism and correlation with treatment induced cardiotoxicity and prognosis in HER2 amplified early breast cancer patients

Introduction: Small studies have indicated a possible correlation between a HER2 gene polymorphism at codon 655 and trastuzumab-associated cardiotoxicity. Association between a synonymous coding variant rs7853758 within the SLC28A3 gene and anthracycline induced cardiotoxicity has also been reported. This study aimed to validate these correlations and assess for any relationship with prognosis.

Methods: Genomic DNA was isolated from 666 patients enrolled in a large trial of adjuvant chemotherapy in HER2 amplified early breast cancer (BCIRG 006). Genotyping was conducted using Sequenom MassARRAY System for HER2 G->A polymorphism at amino acid codon 655 (rs1136201) and variant rs7853758 (L461L) within the SLC28A3 gene.

Results: Of the 666 patients analyzed, 216 patients were treated with anthracycline based therapy, 226 with trastuzumab based therapy, and 224 with regimens containing both an anthracycline and trastuzumab. Compared with the overall results of the BCIRG006 study (N=3,222), in the subset of patients genotyped in this analysis, a less robust improvement in disease free survival (DFS) was observed for the trastuzumab arms than control arm (HR, 0.821). When stratified for prognostic features, the hazard ratio in favor of trastuzumab was consistent with that of the overall study (HR, 0.674). Samples from 662 patients were successfully genotyped for rs1136201. Of these, 424 (64%) were AA, 30 (4.5%) were GG, 208 (31%) were AG genotype. Samples from 665 patients were successfully genotyped for rs7853758. Of these, 19 (3%) were AA, 475 (71%) were GG, and 171 (26%) were AG genotype. There was no correlation seen between mean left ventricular ejection fraction (LVEF) and HER2 genotype at codon 655 in patients treated with trastuzumab. Of patients tested for the HER2 polymorphism, cardiac dysfunction [defined as > 10% decline in LVEF or clinical congestive heart failure (CHF)] developed in 16% of patients with AA, 17% of patients with GG and 20% of patients with AG. There was also no correlation between mean LVEF and variant rs7853758 in patients treated with anthracyclines. The percentage of patients who developed cardiac dysfunction was 13%, 17% and 21% in AA, GG, and AG genotypes respectively. No correlation between disease free survival and any of the genotypes was seen.

Conclusion: In the largest analysis to date to evaluate for relationship between cardiac toxicity and HER2 polymorphism, we did not find a correlation with rs1136201 HER2 polymorphism and trastuzumab induced cardiac toxicity. Our study also did not show a correlation between variant rs7853758 (L461L) and anthracycline induced cardiotoxicity. Neither polymorphism correlated with prognosis.

Citation Format: Peddi PF, Hurvitz SA, Fasching PA, Wang L, Cunningham J, Weinshilboum RM, Liu D, Quinaux E, Fourmanoir H, Robert NJ, Valero V, Crown J, Falkson C, Brufsky A, Pienkowski T, Eiermann W, Martin M, Bee V, Slamon DJ. Genetic polymorphism and correlation with treatment induced cardiotoxicity and prognosis in HER2 amplified early breast cancer patients. [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 P6-03-09.

Kinase inhibitor screening identifies CDK4 as a potential therapeutic target for melanoma

Despite recent advances in targeted therapies and immunotherapies metastatic melanoma remains only rarely curable. The objective of the present study was to identify novel therapeutic targets for metastatic melanoma. A library of 160 well-characterised and potent protein kinase inhibitors was screened in the BRAF mutant cell line Sk-Mel-28, and the NRAS mutant Sk-Mel-2, using proliferation assays. Of the 160 inhibitors tested, 20 achieved >50% growth inhibition in both cell lines. Six of the 20 were cyclin dependent kinase (CDK) inhibitors, including two CDK4 inhibitors. Fascaplysin, a synthetic CDK4 inhibitor, was further tested in 8 melanoma cell lines. The concentration of fascaplysin required to inhibit growth by 50% (IC₅₀ value) ranged from 0.03 to 0.22 μM. Fascaplysin also inhibited clonogenic growth and induced apoptosis. Sensitivity to PD0332991, a therapeutic CDK4/6 inhibitor was also evaluated in the melanoma cell lines. PD0332991 IC₅₀ values ranged from 0.13 to 2.29 μM. Similar to fascaplysin, PD0332991 inhibited clonogenic growth of melanoma cells and induced apoptosis. Higher levels of CDK4 protein correlated with lower sensitivity to PD0332991 in the cell lines. Combined treatment with PD0332991 and the BRAF inhibitor PLX4032, showed additive anti-proliferative effects in the BRAF mutant cell line Malme-3M. In summary, targeting CDK4 inhibits growth and induces apoptosis in melanoma cells in vitro, suggesting that CDK4 may be a rational therapeutic target for metastatic melanoma.

Targeting ADAM-17 with an inhibitory monoclonal antibody has antitumour effects in triple-negative breast cancer cells

Background:

Identification and validation of a targeted therapy for triple-negative breast cancer (TNBC), that is, breast cancers negative for oestrogen receptors, progesterone receptors and HER2 amplification, is currently one of the most urgent problems in breast cancer treatment. EGFR is one of the best-validated driver genes for TNBC. EGFR is normally activated following the release of ligands such as TGFα, mediated by the two MMP-like proteases ADAM (a disintegrin and metalloproteinase)-10 and ADAM-17. The aim of this study was to investigate the antitumour effects of a monoclonal antibody against ADAM-17 on an in vitro model of TNBC.

Methods:

We investigated an inhibitory cross-domain humanised monoclonal antibody targeting both the catalytic domain and the cysteine-rich domain of ADAM17-D1(A12) in the HCC1937 and HCC1143 cell lines.

Results:

D1(A12) was found to significantly inhibit the release of TGFα, and to decrease downstream EGFR-dependent cell signalling. D1(A12) treatment reduced proliferation in two-dimensional clonogenic assays, as well as growth in three-dimensional culture. Furthermore, D1(A12) reduced invasion of HCC1937 cells and decreased migration of HCC1143 cells. Finally, D1(A12) enhanced cell death in HCC1143 cells.

Conclusion:

Our in vitro findings suggest that targeting ADAM-17 with D1(A12) may have anticancer activity in TNBC cells.

Optimally tolerated dose of lapatinib in combination with docetaxel plus trastuzumab in first-line treatment of HER2-positive metastatic breast cancer

BACKGROUND

This phase IB, open-label, dose-escalation study evaluated the safety, tolerability, and optimally tolerated regimen (OTR) of lapatinib in combination with docetaxel and trastuzumab in patients with previously untreated stage IV metastatic breast cancer (MBC) tumors overexpressing human epidermal growth factor receptor 2 (HER2).

PATIENTS AND METHODS

Evaluated dose regimens included lapatinib (500-1500 mg/day), docetaxel (triweekly; 60-100 mg/m²), and trastuzumab (weekly; 2 mg/kg fixed dose); prophylactic granulocyte colony-stimulating factor was included with regimens with ≥750 mg/day lapatinib. End points included OTR and safety/tolerability (primary), overall response rate (ORR), and pharmacokinetics (secondary).

RESULTS

None of the patients (N = 53) experienced dose-limiting toxic effects (DLTs) at the highest dose level; thus, the OTR of lapatinib with 100 mg/m(2) docetaxel was not determined. Common adverse events included diarrhea, nausea, alopecia, fatigue, and rash; grade 3/4 (≥2 patients) were neutropenia, diarrhea, leukopenia, peripheral neuropathy, and rash. Seven patients had DLTs (cycle 1). In 45 patients with measurable disease confirmed by bone scan, investigator-assessed ORR was 31%; without bone scan, confirmation was 64%; 8 patients without measurable disease were evaluated as stable. Lapatinib/docetaxel plasma concentrations were positively associated with complete response.

CONCLUSIONS

Lapatinib/docetaxel/trastuzumab is a feasible and well-tolerated treatment of untreated HER2-positive stage IV MBC. Two lapatinib/docetaxel OTR doses were recommended (1250 mg/75 mg/m²; 1000 mg/100 mg/m²).

CLINICAL TRIAL NUMBER

NCT00251433.

Abstract P4-12-25: Randomized phase II study of pre-operative docetaxel, carboplatin with trastuzumab (TCH) and/or/lapatinib (L) in HER-2 positive (H+) breast cancer patients (BC pts). ICORG 10-05

Background: The addition of trastuzumab (H) to pre-operative chemotherapy in H+BC increases the rate of pathological complete remission (pCR). H causes cardiac toxicity, especially when given with anthracyclines (Anth). TCH is a widely used adjuvant regimen with decreased cardiac toxiciy. We reported that TCH produces pCR in 40% of non-randomised pts with H+BC. Lapatinib is an alternative HER2 antagonist, which produces responses following trastuzumab failure, and which has been reported to augment H activity in combination. We studied the non-Anth regimens TCH v TCL v TCHL in pts with H+BC. The primary objective of this study was pCR. Secondary endpoints were toxicity and translational.

Methods: Eligibility criteria included: primary BC, HER-2 +, node + disease (histologically or cytologically confirmed) or node-negative with >T1, normal left ventricle ejection fraction, no active/uncontrolled cardiovascular disease, normal organ and marrow function. Treatment consisted of 6 cycles of D (75mg/m2) + C (AUC 6) q3 weekly and H (8 mg/kg on cycle 1 day 1 and 6 mg/kg q3weekly thereafter for one year) ± L (1000mg OD) for up to 1 week before surgery. A sample size of 36 evaluable pts is required to detect an absolute 25% difference in the pCR rate between the hypothesised 65% pCR rate vs the historical-control pCR rate of 40%.

Results: Following presentation of NCIC MA31 we decided to suspend accrual on our TCL arm.78 female pts were accrued to TCH/TCHL in 11 ICORG sites between 12/2010- 06/2013. Of 40 patients accrued to TCHL, only 18 pts completed 6 cycles. 17pts came off study early due to toxicity, 3 pts after cycle 3, 2 pts after cycle 2, 12pts after cycle 1. (1 patient was also registered but never started). Of 38 pts accrued to the TCH arm,33 pts completed 6 cycles,2 pts completed 5 cycles and 2 pts w/d after cycle 1. 3 TCHL & 1 TCH pt still remain on Rx. 2 pts have not yet had surgery. 52 SAEs occurred on study, 49 involving hospital admission, & 3 of medical significance. The most frequent SAEs were diarrhoea (10), febrile neutropenia (4), nausea (4), neutropenic sepsis (3), dehydration (2), wound infection (2), vomiting (2) neutropenia (2) decreased haemoglobin (2), GI perforation (1). There was 1 fatality on the TCH arm due to Neutropenic sepsis and typhlitis. One TCHL pt suffered GI perforation at cycle 1. pCR rates were 48% (16/33) for the TCH arm and 44% (7/16) for the TCHL arm. Translational studies are underway.

Conclusions: TCH containing treatment produces a high rate of pCR. TCHL will not produce a statistically higher rate of pCR in this sample. The addition of lapatinib to TCH results in substantial GI toxicity. TCHL appears to be less tolerable than other active chemotherapy +H+L regimens such as that used in Neo-ALLTO. ICORG is currently leading an international study of paclitaxel+H +/- L in metastatic BC.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-12-25.

Emerging targeted therapies in triple-negative breast cancer

Standard chemotherapy regimens can prove effective for patients with early triple-negative breast cancer (TNBC); however, patients with advanced disease typically respond poorly and rapidly progress, and the outcome is poor. New targeted therapies are therefore an urgent unmet medical need for this patient population. Translational and clinical studies into new TNBC treatments have been facilitated by the increased understanding of the aberrant signal transduction pathways regulating growth and survival and the development of chemoresistance in TNBC. Some of the established targeted agents that have been approved in other indications may prove beneficial to patients with TNBC; however, in the absence of approved targeted agents for the treatment of TNBC, most new agents remain experimental. Increased understanding of molecular profiles of TNBC subtypes is likely to improve therapeutic strategies with targeted agents. Novel strategies have reached clinical evaluation in patients with TNBC, including targeting angiogenesis vascular endothelial growth factor and proliferation signalling (receptor tyrosine kinases and mammalian target of rapamycin). Aggressive TNBCs have been found to associate closely with BRCA1 mutation or dysregulation. The recent development of new investigational agents targeting DNA repair, either directly with poly(adenosine disphosphate-ribose) polymerase inhibitors or indirectly through DNA-binding or DNA-damage potentiation, is a major focus of current clinical studies. These and other targeted therapies represent a new approach to TNBC therapy.

ADAM-17: a novel therapeutic target for triple negative breast cancer

BACKGROUND

Validated targeted therapy is currently unavailable for patients with invasive breast cancer negative for oestrogen receptors, progesterone receptors and HER2 [i.e., those with triple-negative (TN) disease]. ADAM-17 is a protease involved in the activations of several ligands that bind to and promotes intracellular signalling from the EGFR/HER family of receptors.

PATIENTS AND METHODS

Expression of ADAM-17 was measured in 86 triple-negative and 96 non-triple-negative breast cancers. The ADAM-17 specific inhibitor, PF-5480090 (TMI-002, Pfizer) was tested in a panel of breast cancer cell lines for effects on functional outputs.

RESULTS

In this study we show using both Western blotting and immunohistochemistry that ADAM-17 is expressed at significantly higher levels in TN than non-TN breast cancers. Using a panel of breast cancer cell lines in culture, PF-5480090 was found to decrease release of the EGFR ligand, TGF-alpha, decrease levels of phosphorylated EGFR and block cell proliferation in a cell-type-dependent manner. Potentially important was the finding of a significant and moderately strong correlation between ADAM-17 activity and extent of proliferation inhibition by PF-5480090 (r = 0.809; p = 0.003; n = 11). Pretreatment of cell lines with PF-5480090 enhanced response to several different cytotoxic and anti-EGFR/HER agents.

CONCLUSION

It is concluded that inhibition of ADAM-17, especially in combination with chemotherapy or anti-EGFR/HER inhibitors, may be a new approach for treating breast cancer, including patients with TN disease.

Overall survival benefit for sequential doxorubicin-docetaxel compared with concurrent doxorubicin and docetaxel in node-positive breast cancer--8-year results of the Breast International Group 02-98 phase III trial

Background In women with node-positive breast cancer, the Breast International Group (BIG) 02-98 tested the incorporation of docetaxel (Taxotere) into doxorubicin (Adriamycin)-based chemotherapy, and compared sequential and concurrent docetaxel. At 5 years, there was a trend for improved disease-free survival (DFS) with docetaxel. We present results at 8-year median follow-up and exploratory analyses within biologically defined subtypes. Methods Patients were randomly assigned to one of four treatments: (i) sequential control: doxorubicin (A) (75 mg/m(2)) × 4 →classical cyclophosphamide, methotrexate, 5-fluorouracil (CMF); (ii) concurrent control: doxorubicin, cyclophosphamide (AC)(60/600 mg/m(2)) × 4 →CMF; (iii) sequential docetaxel: A (75 mg/m(2)) × 3 → docetaxel (T) (100 mg/m(2)) × 3 → CMF and (iv) concurrent docetaxel: AT(50/75 mg/m(2)) × 4 →CMF. The primary comparison evaluated docetaxel efficacy regardless of the schedule. Exploratory analyses were undertaken within biologically defined subtypes. Results Two thousand eight hundred and eighty-seven patients were enrolled. After 93.4 months of median follow-up, there were 916 DFS events. For the primary comparison, there was no significant improvement in DFS from docetaxel [hazard ratio (HR) = 0.91, 95% confidence interval (CI) = 0.80-1.05, P = 0.187]. In secondary comparisons, sequential docetaxel significantly improved DFS compared with sequential control (HR = 0.81, 95% CI = 0.67-0.99, P = 0.036), and significantly improved DFS (HR = 0.84, 95% CI = 0.72-0.99, P = 0.035) and overall survival (OS) (HR = 0.79, 95% CI = 0.65-0.98, P = 0.028) compared with concurrent doxorubicin-docetaxel. Luminal-A disease had the best prognosis. HRs favored addition of sequential docetaxel in all subtypes, except luminal-A; but this observation was not statistically supported because of limited numbers. Conclusion With further follow-up, the sequential docetaxel schedule resulted in significantly better OS than concurrent doxorubicin-docetaxel, and continued to show better DFS than sequential doxorubicin-based control.

Abstract P4-09-06: miR-187 is an independent prognostic factor in lymph node-positive breast cancer patients

Purpose: MicroRNAs (miRNAs) involved in cancer progression have now become the focus of much attention as they represent a new class of biomarkers and potential drug targets. Here, we describe an integrated bioinformatics, functional analysis and translational pathology approach for the identification of novel miRNAs involved in breast cancer progression.

Experimental Design

Differential gene expression can, in part, be attributed to the activity of specific miRNAs. Given a database of miRNA binding site motifs and gene expression levels determined by transcriptomic profiling, correspondence analysis, between group analysis and co-inertia analysis can be combined to produce a ranked list of miRNAs associated with a specific gene signature and phenotype. Here, using two independent breast cancer cohorts, this approach was employed to produce a ranked list of miRNAs associated with disease progression. Functional studies were subsequently carried out in MCF7 cells assessing for alterations in growth, tumorigenicity and agressiveness and miRNA expression was evaluated in two cohorts of breast cancer patients by locked nucleic acid in situ hybridisation on tissue microarrays.

Results: CIA identified miR-187 as a key miRNA associated with poor outcome in breast cancer.

Ectopic expression of miR-187 in MCF7 cells resulted in a more aggressive phenotype (evidenced by increased anchorage-independent growth, migratory and invasive potential).

In a test cohort (n = 117) breast cancer patients, high expression of miR-187 was associated with a trend towards reduced breast cancer-specific survival (BCSS) (p = 0.058), and a significant association with reduced BCSS in lymph node-positive patients (p = 0.036). In a validation cohort (n = 470), high miR-187 was significantly associated with reduced BCSS in the entire cohort (p = 0.021) and, again, in lymph node-positive patients (p = 0.012).

Multivariate cox regression analysis revealed that miR-187 is an independent prognostic factor in both TMA cohorts (Cohort 1 HR-7.369 (95% CI 2.048–26.509, p = 0.002); Cohort 2 HR-2.798 (95% CI 1.518–5.157, p = 0.001).

Conclusions: miR-187 expression in breast cancer leads to the formation of a more aggressive, invasive phenotype and acts as an independent predictor of outcome.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-09-06.

Abstract OT1-1-06: A phase III randomized study of Paclitaxel and Trastuzumab versus Paclitaxel, Trastuzumab and Lapatinib in first line treatment of HER2 positive metastatic breast cancer

Background: Preclinical studies have shown that dual targeting of the extracellular domain and the kinase domain of HER2 using trastuzumab (H) and lapatinib (L) produces greater growth inhibition than single agent treatment. The combination of trastuzumab and lapatinib has shown improved clinical outcome compared to lapatinib alone in the pre-treated metastatic setting (EGF104900), and compared to trastuzumab in the neo-adjuvant setting (Neo-Altto). This international phase III randomised trial will compare the efficacy of trastuzumab and paclitaxel (T) with trastuzumab, paclitaxel and lapatinib in first line treatment of HER2 positive metastatic breast cancer, and will examine potential predictive biomarkers of response to trastuzumab and/or lapatinib.

Study Design and Eligibility: Six hundred patients with invasive HER2 positive (3+ or FISH positive) metastatic breast cancer (measurable disease per RECIST 1.1), who have not received prior systemic therapy for metastatic disease, will be randomised to receive (A) weekly paclitaxel (80 mg/m2, for 3 weeks of a 4 week cycle) plus trastuzumab (8 mg/kg loading dose day 1 and 4mg/kg every 2 weeks) or (B) weekly paclitaxel (80 mg/m2, for 3 weeks of a 4 week cycle) plus trastuzumab (8 mg/kg loading dose day 1 and 4 mg/kg every 2 weeks) plus lapatinib (1,000 mg daily), until disease progression, unacceptable toxicity or consent withdrawal.

Objectives: The primary objective of the study is to compare the efficacy of THL versus TH in first line treatment of metastatic HER2 positive breast cancer. Secondary objectives include: (i) examining the objective tumour response rate and overall survival; (ii) assessing the safety and tolerability of lapatinib when administrated with both paclitaxel and trastuzumab; (iii) examining the effects of the TH regimen versus the THL regimen on health-related quality of life (FACT-B); (iv) examining potential biomarkers in tumour tissue and serum samples; (v) determining if prophylactic loperamide significantly reduces the number of diarrhoea-related adverse events.

Statistical Methods: The expected median progression free survival time for the control arm is 6.9 months based on the trastuzumab plus paclitaxel arm of the phase III trastuzumab plus chemotherapy trial. A total of 600 evaluable patients (and 485 observed events) would be sufficient to detect an increase to 8.9 months in median PFS time for the THL combination, with 80% power and a two sided significance level of 0.05. Progression-free survival will be analysed at nine months after enrolment ends and overall survival will be analysed at 30 months after the end of enrolment. Objective response will be defined as the proportion of patients who receive a complete or partial response as defined by RECIST 1.1.

Accrual: This study will accrue six hundred patients across forty International centres. Countries signed up to participate include Finland, France, Germany, Greece, Iceland, Ireland, Israel, Italy, Netherlands, Norway, Poland, Portugal, Switzerland and Spain. The study opened to accrual in Ireland Feb 12 and six patients have been accrued to date.

Funding: Trial supported by GlaxoSmithKline. Lapatinib kindly supplied by GlaxoSmithKline.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr OT1-1-06.

Abstract P3-04-12: BreastMark: An integrated approach to mining publically available Transcriptomic Datasets relating to Breast Cancer Outcome

Background: Breast cancer is a complex heterogeneous disease for which a substantial resource of transcriptomic data is available. Indeed, gene expression data have facilitated the division of breast cancer into, at least, five molecular subtypes, Luminal A, Luminal B, Her2, Normal-like and Basal. Once identified, breast cancer subtypes can inform clinical decisions surrounding patient treatment and prognosis. It is important to identify patients at risk of developing aggressive disease so as to tailor the level of clinical intervention.

Methods: We have developed a user-friendly web-based system to allow the identification and evaluation of genes that are significantly associated with disease progression and survival for breast cancer in general and also with respect to molecular subtype. The underlying algorithm combines gene expression data from multiple DNA microarray experiments and detailed clinical data to correlate outcome with gene expression levels. This algorithm integrates gene expression and survival data from 21 datasets on 10 different microarray platforms corresponding to 20,017 gene sequences across 3,519 samples.

Results: We demonstrate the robustness of our approach in comparison to two commercially available prognostic tests in breast cancer. Our algorithm complements these prognostic tests and is consistent with their findings. In addition, BreastMark can act as a powerful reductionist approach to these more complex gene signatures, eliminating superfluous genes, potentially reducing the complexity and cost of these multi-index assays. We also applied the algorithm to examine expression of 58 receptor tyrosine kinases in the basal-like subtype of breast cancer, identifying seven receptor tyrosine kinases associated with poor disease-free survival and/or overall survival in this subtype (EPHA5, FGFR1, FGFR3, VEGFR1, PDGFRβ, ROS, TIE1). A web application for using this algorithm is currently available at http://glados.ucd.ie/BreastMark/index.html.

Conclusions: BreastMark is a useful tool for examining putative prognostic markers at the RNA level in breast cancer. The value of this tool will be in the preliminary assessment of putative biomarkers in breast cancer as a whole and within its molecular subtypes. It will be of particular use to clinical and academic research groups with limited bioinformatics facilities.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-04-12.

Abstract S1-6: Results of a randomized phase 2 study of PD 0332991, a cyclin-dependent kinase (CDK) 4/6 inhibitor, in combination with letrozole vs letrozole alone for first-line treatment of ER+/HER2− advanced breast cancer (BC)

Background: PD 0332991, a selective inhibitor of CDK 4/6, prevents cellular DNA synthesis by blocking cell cycle progression. Preclinical studies in a BC cell line panel identified the luminal ER subtype, elevated expression of cyclin D1 and Rb protein, and reduced p16 expression as being associated with sensitivity to PD 0332991 (Finn et al. 2009). Synergistic activity was also observed in vitro when combined with tamoxifen. After determination of the recommended phase 2 dose in combination with letrozole (letrozole 2.5 mg QD plus PD 0332991 125 mg QD on Schedule 3/1), a randomized phase 2 study comparing letrozole alone (L) to letrozole plus PD 0332991 (L+P) was initiated.

Methods: The phase 2 portion of the study was designed as a two-part study; Part 1 enrolled post- menopausal women with ER+/HER2− advanced BC; Part 2 in addition to ER+/HER2− as eligibility criteria, screened for CCND1 amplification and/or loss of p16 by FISH. The primary endpoint is progression-free survival (PFS); secondary endpoints include response rate, overall survival, safety, and correlative biomarker studies. In both parts, post-menopausal women with ER+/HER2− advanced BC were randomized 1:1 to receive letrozole either with or without PD 0332991. Pts continue on assigned study treatment until disease progression, unacceptable toxicity, or consent withdrawal, and are followed for tumor assessments every 2 months.

Results: 66 pts were randomized in Part 1 and 99 pts in Part 2. Preliminary results from Part 1 of this study have been previously reported (IMPAKT Breast Cancer Conference, Abstract #292, Finn et al. May 2012) demonstrating a significant improvement in median PFS in the L+P vs. L arm (HR = 0.35; 95% CI, 0.17 to 0.72; p = 0.006). With the additional 99 pts randomized in Part 2 (N = 165), the statistically significant improvement in median PFS (26.2 vs. 7.5 months, respectively) continues to be observed with a HR=0.32 (95% CI, 0.19 to 0.56) with p <0.001. The response rate for the L+P arm (n = 84) was 31% vs. 26% for the L arm (n = 81) and the clinical benefit rate was 68% vs. 44%, respectively. The most commonly reported treatment-related AEs in the combination arm were neutropenia, leukopenia, anemia, and fatigue. The updated results from the combined Part 1 and Part 2 group will be presented in December 2012.

Conclusions: The combination of PD 0332991 and letrozole is well tolerated and shows encouraging clinical benefit, confirming the sensitivity of ER+ BC to PD 0332991 observed in preclinical models. A phase 3 trial in this setting will commence in 2013.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr S1-6.

Overcoming resistance and restoring sensitivity to HER2-targeted therapies in breast cancer

BACKGROUND

Approximately 15%-23% of breast cancers overexpress human epidermal growth factor receptor 2 (HER2), which leads to the activation of signaling pathways that stimulate cell proliferation and survival. HER2-targeted therapy has substantially improved outcomes in patients with HER2-positive breast cancer. However, both de novo and acquired resistance are observed.

DESIGN

A literature search was performed to identify proposed mechanisms of resistance to HER2-targeted therapy and identified novel targets in clinical development for treating HER2-resistant disease.

RESULTS

Proposed HER2-resistance mechanisms include impediments to HER2-inhibitor binding, signaling through alternative pathways, upregulation of signaling pathways downstream of HER2, and failure to elicit an appropriate immune response. Although continuing HER2 inhibition beyond progression may provide an additional clinical benefit, the availability of novel therapies targeting different mechanisms of action could improve outcomes. The developmental strategy with the most available data is targeting the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) pathway. The oral mTOR inhibitor everolimus has shown promising activity in combination with chemotherapy and trastuzumab in trastuzumab-refractory, advanced breast cancer.

CONCLUSIONS

Non-HER2-targeted therapy is a promising means of overcoming resistance to HER2-targeted treatment. Ongoing clinical studies will provide additional information on the efficacy and safety of novel targeted therapies in HER2-resistant advanced breast cancer.