Abiraterone acetate, exemestane or the combination in postmenopausal patients with estrogen receptor-positive metastatic breast cancer

Resistance to nonsteroidal aromatase inhibitors is a major obstacle in the management of estrogen receptor-positive postmenopausal metastatic breast cancer. The addition of abiraterone acetate to exemestane did not improve clinical outcomes compared with exemestane alone in an androgen receptor-enriched population, potentially due to induced serum progesterone as a resistance mechanism.

Background

Androgen receptor (AR) signaling and incomplete inhibition of estrogen signaling may contribute to metastatic breast cancer (MBC) resistance to a nonsteroidal aromatase inhibitor (NSAI; letrozole or anastrozole). We assessed whether combined inhibition of androgen biosynthesis with abiraterone acetate plus prednisone and estradiol synthesis with exemestane (E) may be of clinical benefit to postmenopausal patients with NSAI-pretreated estrogen receptor-positive (ER+) MBC.

Patients and methods

Patients (N = 297) were stratified by the number of prior therapies for metastatic disease (0–1 versus 2) and by prior NSAI use (adjuvant versus metastatic), and randomized (1 : 1 : 1) to receive oral once daily 1000 mg abiraterone acetate plus 5 mg prednisone (AA) versus AA with 25 mg E (AAE) versus 25 mg E alone (E). Each treatment arm was well balanced with regard to the proportion of patients with AR-positive breast cancer. The primary end point was progression-free survival (PFS). Secondary end points included overall survival, clinical benefit rate, duration of response, and overall response rate.

Results

There was no significant difference in PFS with AA versus E (3.7 versus 3.7 months; hazard ratio [HR] = 1.1; 95% confidence interval [CI] 0.82–1.60; P = 0.437) or AAE versus E (4.5 versus 3.7 months; HR = 0.96; 95% CI 0.70–1.32; P = 0.794). Increased serum progesterone concentrations were observed in both arms receiving AA, but not with E. Grade 3 or 4 treatment-emergent adverse events associated with AA, including hypokalemia and hypertension, were less common in patients in the E (2.0% and 2.9%, respectively) and AA arms (3.4% and 1.1%, respectively) than in the AAE arm (5.8% for both).

Conclusions

Adding AA to E in NSAI-pretreated ER+ MBC patients did not improve PFS compared with treatment with E. An AA-induced progesterone increase may have contributed to this lack of clinical activity.

ClinicalTrials.gov

NCT01381874.

Randomized, phase II, placebo-controlled trial of onartuzumab and/or bevacizumab in combination with weekly paclitaxel in patients with metastatic triple-negative breast cancer

BACKGROUND

Increased hepatocyte growth factor/MET signaling is associated with an aggressive phenotype and poor prognosis in triple-negative breast cancer (TNBC). We evaluated the benefit of adding onartuzumab, a monoclonal anti-MET antibody, to paclitaxel with/without bevacizumab in patients with TNBC.

PATIENTS AND METHODS

Women with metastatic TNBC were randomized to receive onartuzumab plus placebo plus weekly paclitaxel (OP; n = 60) or onartuzumab plus bevacizumab plus paclitaxel (OBP; n = 63) or placebo plus bevacizumab plus paclitaxel (BP; n = 62). The primary end point was progression-free survival (PFS); additional end points included overall survival (OS), objective response rate (ORR), and safety. This trial was hypothesis generating and did not have power to detect minimum clinically meaningful differences between treatment arms.

RESULTS

There was no improvement in PFS with the addition of onartuzumab to BP [hazard ratio (HR), 1.08; 95% confidence interval (CI) 0.69-1.70]; the risk of a PFS event was higher with OP than with BP (HR, 1.74; 95% CI 1.13-2.68). Most patients had MET-negative tumors (88%); PAM50 subtype analysis showed basal-like tumors in 68% of samples. ORR was higher in the bevacizumab arms (OBP: 42.2%; 95% CI 28.6-57.1; BP: 54.7%; 95% CI 41.0-68.4) compared with OP (27.5%; 95% CI 15.9-40.6). Median OS was shorter with OBP (HR, 1.36; 95% CI 0.75-2.46) and OP (HR, 1.92; 95% CI 1.03-3.59), than with BP. Peripheral edema was more frequent in the onartuzumab arms (OBP, 51.8%; OP, 58.6%) versus BP (17.7%).

CONCLUSION

This study did not show a clinical benefit of the addition of onartuzumab to paclitaxel with/without bevacizumab in patients with predominantly MET-negative TNBC.

CLINICALTRIALSGOV

NCT01186991.

Everolimus plus exemestane for hormone-receptor-positive, human epidermal growth factor receptor-2-negative advanced breast cancer: overall survival results from BOLERO-2†

BACKGROUND

The BOLERO-2 study previously demonstrated that adding everolimus (EVE) to exemestane (EXE) significantly improved progression-free survival (PFS) by more than twofold in patients with hormone-receptor-positive (HR(+)), HER2-negative advanced breast cancer that recurred or progressed during/after treatment with nonsteroidal aromatase inhibitors (NSAIs). The overall survival (OS) analysis is presented here.

PATIENTS AND METHODS

BOLERO-2 is a phase III, double-blind, randomized international trial comparing EVE 10 mg/day plus EXE 25 mg/day versus placebo (PBO) + EXE 25 mg/day in postmenopausal women with HR(+) advanced breast cancer with prior exposure to NSAIs. The primary end point was PFS by local investigator assessment; OS was a key secondary end point.

RESULTS

At the time of data cutoff (3 October 2013), 410 deaths had occurred and 13 patients remained on treatment. Median OS in patients receiving EVE + EXE was 31.0 months [95% confidence interval (CI) 28.0-34.6 months] compared with 26.6 months (95% CI 22.6-33.1 months) in patients receiving PBO + EXE (hazard ratio = 0.89; 95% CI 0.73-1.10; log-rank P = 0.14). Poststudy treatments were received by 84% of patients in the EVE + EXE arm versus 90% of patients in the PBO + EXE arm. Types of poststudy therapies were balanced across arms, except for chemotherapy (53% EVE + EXE versus 63% PBO + EXE). No new safety concerns were identified.

CONCLUSIONS

In BOLERO-2, adding EVE to EXE did not confer a statistically significant improvement in the secondary end point OS despite producing a clinically meaningful and statistically significant improvement in the primary end point, PFS (4.6-months prolongation in median PFS; P < 0.0001). Ongoing translational research should further refine the benefit of mTOR inhibition and related pathways in this treatment setting.

TRIAL REGISTRATION NUMBER

NCT00863655.

Bosutinib plus capecitabine for selected advanced solid tumours: results of a phase 1 dose-escalation study

Background:

This phase 1 study evaluated the maximum tolerated dose (MTD), safety, and efficacy of bosutinib (competitive Src/Abl tyrosine kinase inhibitor) plus capecitabine.

Methods:

Patients with locally advanced/metastatic breast, pancreatic, or colorectal cancers; cholangiocarcinoma; or glioblastoma received bosutinib plus capecitabine at eight of nine possible dose combinations using an ‘up-down' design to determine the toxicity contour of the combination.

Results:

Among 32 enrolled patients, none of the 9 patients receiving MTD (bosutinib 300 mg once daily plus capecitabine 1000 mg m⁻² twice daily) experienced dose-limiting toxicities (DLTs). Overall, 2 out of 31 (6%) evaluable patients experienced DLTs (grade 3 neurologic pain (n=1); grade 3 pruritus/rash and increased alanine aminotransferase (n=1)). Most common treatment-related adverse events (AEs) were diarrhoea, nausea, vomiting, palmar-plantar erythrodysesthesia (PPE), fatigue; most frequent grade 3/4 AEs: PPE, fatigue, and increased alanine/aspartate aminotransferase. Although diarrhoea was common, 91% of affected patients experienced maximum grade 1/2 events that resolved. Best overall confirmed partial response or stable disease >24 weeks (all tumour types) was observed in 6 and 13% of patients.

Conclusions:

In this population of patients with advanced solid tumours, bosutinib plus capecitabine demonstrated a safety profile similar to that previously reported for bosutinib or capecitabine monotherapy; limited efficacy was observed.

REBECA: a phase I study of bevacizumab and whole-brain radiation therapy for the treatment of brain metastasis from solid tumours

BACKGROUND

Brain metastases (BMs) are associated with a poor prognosis. Standard treatment comprises whole-brain radiation therapy (WBRT). As neo-angiogenesis is crucial in BM growth, combining angiogenesis inhibitors such as bevacizumab with radiotherapy is of interest. We aimed to identify the optimal regimen of bevacizumab combined with WBRT for BM for phase II evaluation and provide preliminary efficacy data.

PATIENTS AND METHODS

In this multicentre single-arm phase I study with a 3 + 3 dose-escalation design, patients with unresectable BM from solid tumours received three cycles of bevacizumab at escalating doses [5, 10 and 15 mg/kg every 2 weeks at dose levels (DL) 0, 1 and 2, respectively] and WBRT (30 Gy/15 fractions/3 weeks) administered from day 15. DL3 consisted of bevacizumab 15 mg/kg with WBRT from day 15 in 30 Gy/10 fractions/2 weeks. Safety was evaluated using NCI-CTCAE version 3. BM response (RECIST 1.1) was assessed by magnetic resonance imaging at 6 weeks and 3 months after WBRT.

RESULTS

Nineteen patients were treated, of whom 13 had breast cancer. There were no DLTs. Grade 1-2 in-field and out-field toxicities occurred for five and nine patients across all DLs, respectively, including three and six patients (including one patient with both, so eight patients overall) of nine patients in DL3. One patient experienced BM progression during treatment (DL0). At the 3-month post-treatment assessment, 10 patients showed a BM response: one of three treated at DL0, one of three at DL1, two of three at DL2 and six of seven at DL3, including one complete response. BM progression occurred in five patients, resulting in two deaths. The remaining patient died from extracranial disease progression.

CONCLUSION

Bevacizumab combined with WBRT appears to be a tolerable treatment of BM. DL3 warrants further efficacy evaluation based on the favourable safety/efficacy balance. ClinicalTrials.gov Identifier: NCT01332929.

Randomised proof-of-concept phase II trial comparing targeted therapy based on tumour molecular profiling vs conventional therapy in patients with refractory cancer: results of the feasibility part of the SHIVA trial

Background:

The SHIVA trial is a multicentric randomised proof-of-concept phase II trial comparing molecularly targeted therapy based on tumour molecular profiling vs conventional therapy in patients with any type of refractory cancer. Results of the feasibility study on the first 100 enrolled patients are presented.

Methods:

Adult patients with any type of metastatic cancer who failed standard therapy were eligible for the study. The molecular profile was performed on a mandatory biopsy, and included mutations and gene copy number alteration analyses using high-throughput technologies, as well as the determination of oestrogen, progesterone, and androgen receptors by immunohistochemistry (IHC).

Results:

Biopsy was safely performed in 95 of the first 100 included patients. Median time between the biopsy and the therapeutic decision taken during a weekly molecular biology board was 26 days. Mutations, gene copy number alterations, and IHC analyses were successful in 63 (66%), 65 (68%), and 87 (92%) patients, respectively. A druggable molecular abnormality was present in 38 patients (40%).

Conclusions:

The establishment of a comprehensive tumour molecular profile was safe, feasible, and compatible with clinical practice in refractory cancer patients.

Activity of trabectedin in germline BRCA1/2-mutated metastatic breast cancer: results of an international first-in-class phase II study

BACKGROUND

Breast cancer is a heterogeneous disease defined by both germline and somatic abnormalities. In preclinical models, tumors carrying homologous recombination defects are highly sensitive to trabectedin. This phase II trial evaluated the efficacy and safety of trabectedin in BRCA1/2 germline mutation carriers with pretreated metastatic breast cancer (MBC).

PATIENTS AND METHODS

Trabectedin 1.3 mg/m(2) as a 3-h i.v. infusion was administered every 3 weeks until progression or intolerance. The primary efficacy end point was the objective response rate (ORR) as per RECIST. Secondary efficacy end points comprised time-to-event end points, and changes in tumor volume and expression of tumor marker CA15.3. Safety was evaluated using the NCI-CTCAE.

RESULTS

Forty BRCA1/2 germline mutation carriers with MBC were included. Confirmed partial response (PR) occurred in 6 of 35 assessable patients [ORR = 17%; 95% confidence interval (CI) 7% to 34%] and lasted 1.4-6.8 months. Median PFS was 3.9 months (95% CI 1.6-5.5 months). Eight patients (21%) showed changes in tumor volume, and 14 (40%) a clinical benefit. Trabectedin-related adverse events were generally mild/moderate, the most common being fatigue, nausea, constipation and anorexia. Severe laboratory abnormalities (neutropenia, transaminase increases) were mostly transient and noncumulative, and were managed by dose adjustments.

CONCLUSIONS

With the caveat of the limited patient number, trabectedin monotherapy showed activity and was well tolerated in heavily pretreated MBC patients selected for germline BRCA mutation. These results prompt further evaluation of trabectedin alone or combined with other specific drugs in this indication.

CLINICALTRIALSGOV

NCT00580112.

Pathological complete response after neoadjuvant chemotherapy is an independent predictive factor irrespective of simplified breast cancer intrinsic subtypes: a landmark and two-step approach analyses from the EORTC 10994/BIG 1-00 phase III trial

BACKGROUND

Pathological complete response (pCR) following chemotherapy is strongly associated with both breast cancer subtype and long-term survival. Within a phase III neoadjuvant chemotherapy trial, we sought to determine whether the prognostic implications of pCR, TP53 status and treatment arm (taxane versus non-taxane) differed between intrinsic subtypes.

PATIENTS AND METHODS

Patients were randomized to receive either six cycles of anthracycline-based chemotherapy or three cycles of docetaxel then three cycles of eprirubicin/docetaxel (T-ET). pCR was defined as no evidence of residual invasive cancer (or very few scattered tumour cells) in primary tumour and lymph nodes. We used a simplified intrinsic subtypes classification, as suggested by the 2011 St Gallen consensus. Interactions between pCR, TP53 status, treatment arm and intrinsic subtype on event-free survival (EFS), distant metastasis-free survival (DMFS) and overall survival (OS) were studied using a landmark and a two-step approach multivariate analyses.

RESULTS

Sufficient data for pCR analyses were available in 1212 (65%) of 1856 patients randomized. pCR occurred in 222 of 1212 (18%) patients: 37 of 496 (7.5%) luminal A, 22 of 147 (15%) luminal B/HER2 negative, 51 of 230 (22%) luminal B/HER2 positive, 43 of 118 (36%) HER2 positive/non-luminal, 69 of 221(31%) triple negative (TN). The prognostic effect of pCR on EFS did not differ between subtypes and was an independent predictor for better EFS [hazard ratio (HR) = 0.40, P < 0.001 in favour of pCR], DMFS (HR = 0.32, P < 0.001) and OS (HR = 0.32, P < 0.001). Chemotherapy arm was an independent predictor only for EFS (HR = 0.73, P = 0.004 in favour of T-ET). The interaction between TP53, intrinsic subtypes and survival outcomes only approached statistical significance for EFS (P = 0.1).

CONCLUSIONS

pCR is an independent predictor of favourable clinical outcomes in all molecular subtypes in a two-step multivariate analysis.

CLINICALTRIALSGOV

EORTC 10994/BIG 1-00 Trial registration number NCT00017095.

Abstract P6-12-08: Serum biomarkers identification using quantitative proteomics in patients with HER2-positive inflammatory breast cancer receiving trastuzumab plus bevacizumab-based chemotherapy (BEVERLY 2 trial)

Background

Inflammatory breast cancer (IBC) is a rare but aggressive form of locally advanced breast cancer, the optimal systemic treatment of which is still discussed. Beverly 2 trial was a phase II study evaluating the efficacy and safety of a preoperative regimen associating bevacizumab, trastuzumab, and chemotherapy in 52 patients with non-metastatic HER2-positive IBC, reporting a promising rate of pathological complete response (pCR, 63.5%, 95% CI 49.4–77.5; Pierga et al, Lancet Oncol, 2012). During the study, serum samples were collected at baseline and subjected to proteomic-based approaches to identify circulating biomarkers predictive of treatment response.

Methods

Baseline serum samples from responsive (pCR, according to Sataloff classification, n = 12) and non-responsive (no pCR, n = 11) patients were subjected to isobaric Tag for Relative and Absolute Quantification (iTRAQ)-based proteomics. Samples were pooled according to pCR and hormone receptor (HR) status, to constitute 4 independent mixes (pCR/HR-positive, pCR/HR-negative, nopCR/HR-positive, nopCR/HR-negative). Each of them underwent immuno-depletion of highly abundant proteins, concentration, reduction, alkylation and tryptic digestion. Then, each mix was fractionated and subjected to iTRAQ identification and quantitation using nano-liquid chromatography (LC) and electrospray ionisation (ESI)-orbitrap tandem mass spectrometry (MS/MS) (LTQ-orbitrap, Thermofisher). Differentially expressed proteins were analysed using IPA (IngenuitySystems) to highlight biological functions and signalling pathways that were most significantly enriched.

Results

iTRAQ-based measurements identified and quantified a total of 302 serum proteins. Among them, 48 proteins displayed a significant (fold-change &gt; 1.5 and p-value &lt; 0.05) differential expression between pCR and noPCR pts (18 proteins down-regultated and 30 proteins up-regulated in pCR patients), some of them previously described to be involved in breast cancer biology and/or angiogenesis, including : Alpha-1-acid glycoprotein 1, von Willebrand factor, Galectin-3-binding protein, serum amyloid A-1, Apolipoprotein E, Pigment epithelium-derived factor, Corticosteroid-binding globulin (down-regulated proteins in pCR patients); serum amyloid P-component, angiotensinogen, plasma serine protease inhibitor, carbonic anhydrase 1, mannose-binding protein C, hyaluronan-binding protein 2, peroxiredoxin-2, properdin, ADAMTS13, tetranectin, biotinidase, lumican (up-regulated proteins in pCR patients). Proteins with differential expression during treatment were involved in various biological processes, including cell-to-cell signaling and interaction, lipid metabolism, small molecule biochemistry, molecular transport, cellular function and maintenance as well as various canonical pathways such as acute phase response signalling, LXR/RXR activation and coagulation system.

Conclusion

iTRAQ-based quantitative proteomics identify serum proteins that could predict the therapeutic response to pre-operative trastuzumab plus bevacizumab-based chemotherapy in HER2-positive IBC.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-12-08.

Abstract P4-01-05: 3’-deoxy-3’-[18F]fluoro-thymidine (18F-FLT) positron emission tomography (PET): An accurate and effective tool for assessing tumor response in breast cancer

Objectives : A French multicenter study was promoted by the national French cancer federation (Unicancer R&D) to assess the potential of [18F]FLT (positron emission tomography (PET) biomarker of proliferation)to manage breast cancer neoadjuvant chemotherapy (NAC). The main objective was to compare changes in tumor [18F]FLT uptake to histopathological changes induced by NAC, assuming an arrest of tumor growth related to the effectiveness of NAC.

Methods : 97 patients (age 48.6 +/- 10.2 y.) were included in 13 nuclear medicine centers. All patients were eligible to anthracycline-based NAC for a de novo unifocal breast cancer (ductal n = 84, lobular = 11, other type = 2; stage II n = 75, stage III n = 21 et stage IV n = 1). 90 patients underwent a baseline PET before the onset of NAC (PET1) and a final PET after the end of NAC and before surgery (PET3). PET acquisitions were performed 60±7min after FLT injection. SUVmax (maximum standardized uptake value), SUVpeak (1 cm3 ROI including pixel max) and SUV41 (isocontour 41% of pixel max) were computed. Changes in SUV on PET3 vs PET1 were analyzed in relation to histopathological findings at the end of NAC (Sataloff criteria).

Results : Tumor FLT uptake decreased markedly between TEP1 and TEP3 (SUVmax = 6.2±4.8 vs 1.3±1.2 respectively; SUVpeak = 4.6±3.2 vs 0.9±0.9; SUV41 = 3.6±2.8 vs 0.8±0.7). Total or near-total therapeutic effect (grade A) were obtained in 20 patients, more than 50% therapeutic effect but less than total or near-total effect (grade B) in 37 patients, less than 50% therapeutic effect but visible effect (grade C) in 22 patients, or no therapeutic effect (grade D) in 11 patients. SUVmax decreased dramatically (87.5%) to background levels in all patients with a complete response (grade A). Overall, changes in SUV differed depending on the type of histological response (p&lt;0.01) i.e. SUVmax changes were more pronounced as pathological responses were good: 61% for grade D; 65.7% grade C and 69.8% grade B. The same results were obtained with the two other SUV types.

Conclusions : Pathologic response to NAC in breast cancer can be assessed accurately by FLT.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-01-05.

Abstract P2-05-05: Canine invasive mammary carcinoma as a spontaneous model for insulin-like growth factor-1 receptor-overexpressing triple negative breast cancer

Background: Dogs spontaneously develop invasive mammary carcinoma with a high prevalence of the triple-negative subtype, making this model relevant for the investigation of new therapeutic pathways. Insulin-like growth factor-1 receptor (IGF-1R) is extensively involved in malignant transformation, proliferation and metastasis in human breast cancer and multiple clinical trials have used IGF-1R inhibitors with encouraging results.

Aims: To quantify IGF-1R expression in canine triple-negative invasive mammary carcinoma (TN-CMC) and assess its prognostic value (overall, specific and disease-free survival). To validate the dog as a spontaneous animal model for preclinical trials targeting IGF-1R in triple-negative breast cancer.

Material and methods: 104 triple-negative canine invasive mammary carcinomas (Estrogen receptor negative, Progesterone receptor negative, not HER2 overexpressing) were included. Bitches were followed for at least 2 years after mastectomy. TN-CMC were classified as basal-like (Cytokeratin-CK 5/6 positive and/or Epidermal Growth Factor Receptor-EGFR positive) and non-basal-like (CK 5/6 and EGFR negative). IGF-1R expression (clone G11) was quantified using the same scoring system as for HER2 in breast cancer.

Results: 68.3% (n = 71/104) of the TN-CMC were classified as basal-like and 31.7% (n = 33/104) as non-basal-like. 45.2% (n = 47/104) of TN-CMC overexpressed IGF-1R (score 3+), of which 70.2% (n = 33/47) were basal-like and 61.7% (n = 29/47) were grade III. Univariate and multivariate analyses revealed that IGF-1R overexpression (score 3+) was associated with significantly shorter overall, specific and disease-free survivals (median: 163, 332 and 278 days respectively) than weak (score 1+) IGF-1R expression (median: 842 days, not achieved and 1011 days respectively).

Conclusion and perspectives: IGF-1R overexpression is common and related to a poor outcome in canine triple-negative invasive mammary carcinoma. Preclinical studies using the dog as a spontaneous animal model for triple-negative breast cancer could be considered to investigate new therapies targeting IGF-1R.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-05-05.

Abstract P2-05-08: Combined neoadjuvant iniparib and carboplatin in locally advanced or metastatic canine mammary tumors (MT) to support human clinical studies

INTRODUCTION

Among breast cancers, the triple negative subtype (negative for hormone receptors and not overexpressing HER2) has the worst prognosis and its response to Iniparib has been investigated in clinical trials. Further investigations are needed to optimize drug schedule and patient selection criteria. Iniparib antitumor mechanism is not completely understood, as well as iniparib diffusion kinetic into tumoral tissues. We address these questions in spontaneous canine invasive mammary carcinomas, which are a good model for this cancer subtype (Ibisch et al., World Veterinary Cancer Congress 2012), in a neoadjuvant setting. To our knowledge, this is the first study of iniparib administration in cancer-bearing dogs.

MATERIAL AND METHODS

Twenty female dogs with spontaneous MT with malignant criteria (tumor size, speed of growth, ulceration, relapse, or metastasis) were included. All tumors were described as rapidly growing. Dogs received a first infusion of iniparib at day 0 and a combination of carboplatin and iniparib at day 7. Biological materials (tumor biopsies and blood) were collected before and 5 minutes after iniparib infusion for pharmacokinetic and metabolism studies. Tumor response was evaluated by caliper measurements and histopathological analysis of mammary tumors and draining lymph nodes. A chain mastectomy was performed 3 or 4 weeks later. Histological records included the subtype of carcinoma (WHO 1999), Elston & Ellis grade, presence of emboli, lymph node metastasis and IHC stainings using ER, PR, Her2 (scored according to Wolff et al.2007), CK5/6, EGF-R and Ki67. Intensity of necrosis and apoptosis was evaluated using PAS coloration and immunohistochemistry for caspase 3, at DO on tumor biopsies and at surgery. Toxicity of the protocol was evaluated and its efficiency on invasive carcinomas was compared to surgery alone (control group of 27 female dogs with invasive mammary carcinomas treated by chain mastectomy alone).

RESULTS

Treated and control groups shared similar features concerning animal breeds, age, neutering status and tumor location. 75% of the treated MT were malignant. Necrosis and apoptosis were significantly increased in respectively 63 and 56% of iniparib treated tumors. Clinical evidence of toxicity was minimal (15% of dogs with nausea, 60% with transient polyuria-polydipsia). Tumor stabilization was observed before surgery in all dogs but one. Median survival has not been reached.

CONCLUSION

Iniparib at 35mg/kg combined with carboplatin at 300 mg/m2 seemed well tolerated in this study and deserves further investigations. The degree of necrosis and apoptosis in the treated tumors can be evaluated with these techniques. Iniparib pharmacokinetic and metabolism studies in cancer-bearing dogs are ongoing.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-05-08.

Abstract P1-08-27: Quantitative analysis of tumor expression of phosphoproteins from PI3-kinase and MAP-kinase signaling pathways as biomarkers of the biological and clinical activity of trastuzumab and everolimus in breast cancer: Unicancer RADHER phase II trial results

Background: PI3-kinase (PI3K) and MAP kinase (MAPK) are the main signaling pathways implicated in molecular oncogenesis. In breast cancer, inhibition of these signaling pathways has been largely envisaged by means of targeted therapy. Unicancer RADHER study aimed at evaluating the efficacy of adding everolimus (E) to trastuzumab (T) as preoperative therapy for primary HER2+ operable breast cancer patients and to evaluate molecular response biomarkers. We report here the investigation of the expression of phosphoproteins from PI3K and MAPK signaling pathways as predictive biomarkers of clinical and pathological response as well as pharmacodynamic markers of treatment activity.

Methods: 82 eligible patients were randomized to receive T alone (loading dose 4 mg/kg, then 2 mg/kg/week), or T+E (10 mg/day) for a 6-week pre-operative treatment. Clinical response rate (cRR) was determined from OMS criteria with complete and partial responses being considered as “ responders “ and stable and progressive diseases as “ non responders “. Pathological response rate was evaluated according to Sataloff classification, with Ta and Tb being considered as “ responders “ and, Tc and Td as “ non responders “. The expression levels of phosphorylated-AKT (p-AKT), p-GSK3b, p-S6 kinase, p-MEK1, p-ERK1/2, p-P90RSK, p-IGF1R as well as p-P38MAPK were quantitatively assessed using multiplex bead immuno-assay. All patients had baseline needle frozen biopsies taken before initiation of the treatment, at cycle 4 as an option and at surgery. Before being submitted to total protein extraction, all biopsies were validated by a senior pathologist after HE slide examination to ensure a tumor content &gt;50%. 36 pairs associating baseline + surgery tumor specimens and 4 pairs of baseline + cycle 4 biopsies were eligible for protein extraction. Results: No statistically significant relationship was observed between the expression level of any of the phosphoproteins in the initial biopsies and neither the clinical nor the pathological response, overall. After treatment, as compared to the level of expression measured in the initial biopsies, a significant increase of p-GSK3β, p-MEK1, p-ERK1/2, p-P38MAPK was observed in T+E arm and a significant decrease in p-S6 kinase expression in the global patient population. No significant variation was observed in T arm. Additional analysis with immunohistochemistry data is planned and will be presented.

Conclusion: In the present study, measuring phosphoproteins expression showed that combining E with T, altered the regulation of signaling proteins from PI3-Kinase and MAP-kinase pathways. No response predictive biomarker could be identified among the phosphoproteins analyzed tending to show that the clinical and pathological response to T and T+E should be driven by additional mechanisms. As a whole, these results validate the use of multiplex bead immuno-analysis for determination of phosphorylated signaling proteins in clinical needle biopsies from breast cancer specimens and its prospective evaluation as biomarker for the activity of targeted therapies.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-27.

Abstract S6-07: Genomic characterisation of metastatic samples from breast cancer patients using next generation sequencing

Background: Although several studies have reported genomic characterisation of primary breast tumors, little is known about the genomic alterations of the metastatic tissues. Breast cancer patients who were prospectively enrolled in a trial (SAFIR01) underwent a biopsy of metastasis. The primary aim of this biopsy was to drive the treatment according to the results of whole genome CGH arrays and sanger sequencing on two genes (PIK3CA and AKT1). The results of the clinical trial were previously reported (André et al ASCO 2013). The secondary goal of the biopsies was to perform genomic characterisation of metastases in breast cancer patients. Here we report the analyses of such metastatic samples using next generation sequencing (NGS) approaches.

Patients and methods: Two approaches were applied. In order to describe the incidence of targetable genomic alterations, we performed in depth targeted sequencing on 100 genes (200x coverage) using Illumina HiSeq 2000 (DNA vision). This analysis was performed on 240 metastatic samples. The second approach was more exploratory and aimed at discovering new genes involved in the metastatic process and/or resistance to therapies. In order to achieve this goal, we performed whole exome sequencing in 100 pairs of metastatic tissue (100x) and normal DNA (Integragen Inc, Hiseq platform). Finally, phosphor-S6K staining was performed in 300 samples in order to explore the activation status of mTOR pathway in metastatic disease, and to correlate with genomic data.

Results: Targeted sequencing was performed on 240 metastatic samples in order to report the prevalence of targetable genomic alterations in metastatic breast cancer. Results are available for the first 159 samples. In addition to the already reported PIK3CA (26%) and AKT1 mutations (4%), NGS identified mutations of PTEN (4%), ERBB2 (2%), K-Ras (1%), ATM (2%), CDH1 (2%), GATA3 (2%), PTPN11 (1%), PTPRD (1%), ROS1 (1%). Results on the 81 samples, together with whole exome sequencing (n = 100) and phosphoproteins are being analysed and results will be available mid-november 2013.

Conclusion: This is the first large study that aims at defining the genomic landscape of metastatic samples. Results will provide insights into the prevalence of targetable genomic alterations in metastatic tissue, together with candidate genes involved in the metastatic process and resistance to therapies.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S6-07.

Circulating tumor cells and brain metastasis outcome in patients with HER2-positive breast cancer: the LANDSCAPE trial

BACKGROUND

Decrease of circulating tumor cells (CTC) during treatment is an independent prognostic factor in metastatic breast cancer (MBC). We specifically evaluated the impact of CTC on brain metastasis outcome.

METHODS

HER2-positive MBC with brain metastasis not previously treated with whole-brain radiotherapy received first-line combination of lapatinib and capecitabine in a phase II study. CTC were detected at baseline and day 21 (CellSearch).

RESULTS

Median follow-up of the 44 analyzed patients was 21.2 months. The central nervous system objective response (CNS-OR) rate was 66%. At baseline, 20 of 41 assessable patients for CTC (49%) had ≥1 CTC (range 1-301, median 3) and 9 (22%) had ≥5 CTC. At day 21, 7 of 38 patients (18%) had ≥1 CTC (P = 0.006, versus baseline), and CTC had disappeared in 11 patients. CNS-OR rate was significantly higher in patients with no CTC at day 21 [25 of 31 (80%) versus 2 of 7 (29%), P = 0.01]. The 1-year overall survival rate was 83.9% in patients with no CTC at day 21 versus 42.9% in patients with ≥1 CTC (P = 0.02).

CONCLUSIONS

This is the first report showing a correlation between CNS metastasis response, outcome and early CTC clearance under targeted treatment of HER2+ MBC.

CLINICAL TRIALS NUMBER

NCT00967031.

Abstract P2-01-13: Prognostic value of Circulating Tumor Cells count at progressive disease after first line chemotherapy metastatic breast patients in a large prospective multicenter trial including serum tumor markers (IC 2006–04 study)

Background: The IC 2006–04 study included prospectively 267 metastatic breast cancer patients before the start of first line chemotherapy. We previously reported and confirmed the prognostic and predictive of CTC counts before the start of treatment and after 3–4 & 6–9 weeks of treatment (Pierga, JY SABCS 2010, Ann Oncol 2012). We report here the results of the last CTC count performed at tumor progression (i.e. end of first line chemotherapy).

Methods: Patients were included in the study from 06/07 to 9/09. CTC were counted by the CellSearch® system at tumor progression (clinical and/or radiological progression).

Results: 211 patients experienced a tumor progression at time of final data analysis and the planned CTC count has been performed in 61 patients. High CTC count (≥5 CTC/7.5ml) at progression was observed in 22 patients (36%) and was associated with elevated Cyfra 21–1 and ALP and was not associated with elevated CEA, CA 15–3, LDH, the elapsed progression-free survival, the onset of new metastasis. No CTC was detected at tumor progression in the 5 patients with HER2+ disease, in line with our previous results. The prognostic markers for overall survival at tumor progression were high CTC count (median overall survival 8 vs 19 months, p = .0006) and elevated Cyfra 21–1 (p = .001). Other serum markers (CEA, CA15-3, ALP, LDH) and tumor subtypes had no prognostic value at univariate analysis. At multivariate analysis, the two prognostic factors for overall survival were high CTC count (RR = 2.3 p = 0.03) and elevated Cyfra 21–1 (RR = 3.6 p = 0.02).

Conclusion: In the prospective IC 2006–04 study, among the different markers tested at tumor progression during the first line chemotherapy for metastatic breast cancer, high CTC count and elevated Cyfra 21–1 levels were the only two independent prognostic markers for overall survival.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-01-13.

Abstract P6-11-08: A multicenter, open-label Ph IB/II study of BEZ235, an oral dual PI3K/mTOR inhibitor, in combination with paclitaxel in patients with HER2-negative, locally advanced or metastatic breast cancer

Background: The PI3K/AKT/mTOR pathway is frequently altered in breast cancer (BC). Alterations in PIK3CA or inactivation of PTEN are observed in 10–40% and in up to 50% of breast tumors, respectively. The PI3K/AKT/mTOR pathway can be further activated through various receptor classes or cross-talk with other pathways, making it a rational target for therapeutic intervention in BC. BEZ235 is an oral dual inhibitor of mTOR and PI3K. It has demonstrated anti-proliferative activity, substantial growth inhibition, and induction of apoptosis in preclinical studies. In a Ph I study, single-agent BEZ235 (600 mg BID) was shown to have less toxicity than the equivalent once-daily dosing, and have preliminary evidence of activity in advanced solid tumors (Arkenau, et al. ASCO 2012:#3097).

Methods: This is a multicenter, open-label Ph IB/II study of continuous, oral BEZ235 twice daily (BID) in combination with paclitaxel (80 mg/m2; IV weekly [QW]) in women with HER2-negative (HER2–), metastatic or inoperable locally advanced BC (NCT01495247).

For the Ph IB part, women with HER2–, metastatic or inoperable locally advanced BC, who are suitable for treatment with paclitaxel, are eligible for enrollment. The primary objective is to determine the maximum tolerated dose (MTD)/recommended Ph II dose (RP2D) of BEZ235 in combination with paclitaxel based on dose-limiting toxicities (DLTs) using an adaptive 5-parameter Bayesian logistic regression model with overdose control. The MTD is defined as the highest drug dosage not causing medically unacceptable DLTs in more than 35% of the treated patients during Cycle 1 (1 cycle = 28 days). Secondary objectives include safety (CTCAE), preliminary activity (RECIST), and pharmacokinetics (PK). Estimated enrollment is 15–30 patients into the Ph IB part.

Results: As of June 2012, 13 pts have been enrolled into the Ph IB part of the trial. The first cohort (n = 7 pts) received BEZ235 200 mg BID + 80 mg/m2 QW paclitaxel. Of these 7 pts, 3 are ongoing, with 2 pts having received treatment for more than 12 weeks so far, and 4 pts have discontinued (2 due to an adverse event [AE]; 1 due to an AE/pt's decision; and 1 due to disease progression). Of the 6 evaluable pts in the first cohort, 2 experienced DLTs: Grade 3 stomatitis (1 pt) and Grade 2/3 neutropenia (1 pt). Most common AEs included stomatitis and GI toxicity (e.g. diarrhea, nausea/vomiting). To date, reported Grade 3 AEs related to study drug were stomatitis (2 pts), neutropenia (1 pt), and skin rash (1 pt). Among the 3 pts with at least one tumor evaluation, 1 pt with a triple-negative metastatic BC, who had previously been treated with paclitaxel, experienced a RECIST partial response which was confirmed on second tumor evaluation. PK analysis is ongoing.

Conclusions: Additional patients have been enrolled at BEZ235 200 mg BID/paclitaxel 80 mg/m2 QW to provide further information on the safety and activity profile of this combination. Updated safety and efficacy results will be presented. Upon determination of the MTD/RP2D, the randomized Ph II part will begin to compare weekly paclitaxel given with or without BEZ235 BID as the first-line treatment of HER2– metastatic BC.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-11-08.

Abstract P3-05-07: Poor prognosis early breast cancer: pathological characteristics of the Unicancer-PACS08 trial including patients treated with docetaxel or ixabepilone in adjuvant setting

Background: The PACS08 trial aimed to compare adjuvant FEC100-Docetaxel regimen to FEC100-Ixabepilone (Ixa) in poor prognosis early breast cancer (BC). The study population included BC patients presenting with triple-negative (TN) [i.e. estrogen receptor (ER)−/progesterone receptor (PR)−/HER2−] or ER+/PR−/HER2− tumor, which are subgroups significantly associated with worse prognosis. Central review was performed and detailed pathological characteristics of the cohort are reported herein.

Patients and method: Between 2007 and 2010, 762 patients with unilateral TNBC (n = 592, 78%) or ER+/PR−/HER2− BC (n = 170, 22%) were enrolled. Recruitment was interrupted due to BMS decision to stop Ixa development in adjuvant setting. As defined by inclusion criteria, TNBC were either node+ or node-, and ER+/PR−/HER2− BC only node+. Following the validation of ER, PR and HER2 status on whole sections prior to inclusion, paraffin blocks (n = 754) were sent for central pathology review, tissue microarray (TMA) construction and constitution of the trial collection for translational research studies. Review of the cases (n = 754) was performed by a board of expert breast pathologists on a one-week working session with discussion of the difficult cases under a multihead microscope. Tumor characteristics were assessed on whole tissue sections. Immunohistochemical detection of Ki67, EGFR, cytokeratins (CK)5/6 and 14, was performed on TMAs.

Results: TNBC were significantly associated with younger age at diagnosis (median age 51yr vs 57.5yr in the ER+/PR- subgroup, p &lt; 0.001). Most tumors were invasive ductal carcinomas (72%). Distribution of special histological subtypes was significantly different in the TNBC and ER+/PR−/HER2− subgroups, with the former comprising medullary (n = 16/17) and metaplastic (n = 34/34) subtypes while the latter was enriched in invasive lobular carcinomas (n = 27/35, p &lt; 0.0001). TNBC were significantly associated with higher histological grade as compared to ER+/PR−/HER2− subgroup (Table 1). Accordingly, TNBC displayed significantly higher proliferative activity as shown by mitotic count and Ki67 index (p &lt; 0.001). As compared to ER+/PR−/HER2− subgroup, TNBC showed distinct characteristics, and displayed a so-called basal-like phenotype in 80%. Among the ER+/PR−/HER2− subgroup, most tumors were classified as luminal B (64%). Interestingly, the presence of tumor lymphocytic infiltrate was more frequently observed in luminal B (59%) as compared to luminal A (30%) subtype (p &lt; 0.001).

Abstract P3-04-04: Identification of a “BRCAness” signature in triple negative breast cancer by Comparative Genomic Hybridization

Background: Triple Negative Breast Cancers (TNBC) represent 12% to 20% of total Breast Cancers (BC) and have a worse outcome compared with other breast cancer subtypes. TNBC often show a deficiency in DNA double strand break repair mechanisms. This deficiency is generally related to inactivation of a repair enzymatic complex involving BRCA1 caused either by genetic mutations, epigenetic modifications, or by post-transcriptional regulations. The identification of BC presenting a BRCA1 deficiency could be useful to select patients that could benefit from PARP inhibitors, alkylant agents or platinum-based chemotherapy.

In this study, we have identified by Comparative Genomic Hybridization array (CGH-array) a recurrent gain in 17q25.3 characteristic of BRCA1 mutated or methylated TNBC.

Methods: 130 formalin-fixed paraffin embedded (FFPE) tumours including TNBC (unknown-BRCA1-status, BRCA1 mutated and non-mutated), Luminal A, Luminal B, Her2-neu amplified (Her2+) BC and BRCA1-mutated non-TNBC (mutated-Luminal A, Luminal B, Her2+) were obtained from our local tumour collection. DNA was extracted and genomic copy-number alterations were analysed by CGH-array (Agilent, SuperPrint G3 Human CGH 8×60K Oligo Microarrays). FISH analyses were performed on section from FFPE samples to validate some chromosomal aberrations belonging to the 17q25.3 amplified region evidenced by CGH-array. The study of BRCA1 promoter methylation status in all tumours was carried out by MDxHealth (Liege, Belgium).

Results: In this study, we have identified by CGH-array a genomic region (17q25.3) amplified in 90% of the BRCA1 mutated tumours (29/32). This chromosomal gain was studied in other subtypes of BC by CGH-array and it was only evidenced in 30% (6/20) of BRCA1 non-mutated TNBC, 26.67% (4/15) of unknown-BRCA1-status TNBC, 13.64% (3/22) of Luminal B, 19.05% (4/21) of Her2+ and 0% (0/20) of Luminal A breast cancers. FISH assays confirmed these chromosomal amplifications and evidenced like CGH array analyses a significant difference between BRCA1 mutated and non-mutated BC for the 17q25.3 gain.

BRCA1 methylation was found only in TNBC (11/58) and was not found in the BRCA1-mutated BC cohort, nor in the Luninal A, Luminal B and Her2+ samples. In BRCA1 non-mutated TNBC, the methylation was found in 8 cases including 4 with 17q25.3 amplification. In the unknown-BRCA1-status TNBC, 3 methylated samples were found with 1 case with co-amplification of the 17q25.3 region.

Recurrence of 17q25.3 amplification in BRCA1 mutated tumours as well as its detection in BC having a methylation in BRCA1 promoter suggests that the 17q25.3 gain could be a marker of the BRCA1 deficiency. Identification of relevant genes whose expression is up-regulated within the recurrently gained region is underway.

Conclusions: The CGH signature observed in 17q25.3 chromosomal region and FISH assay developed in this study could allow the identification of “BRCAness” breast tumours, improving the diagnostic performance and orienting the selection of the appropriate therapy. The up-regulated genes themselves might also represent potential therapeutic targets.

Acknowledgements: This work was financed through the “Plan National Cancer-Action 29” (Belgium) and supported by the UNICANCER-PACS08 trial (France).

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

Abstract OT2-2-03: Dovitinib (TKI258) or placebo in combination with fulvestrant in postmenopausal, endocrine-resistant HER2–/HR+ breast cancer: a phase II study

Background: Overcoming endocrine resistance is a critical goal in the treatment of hormone receptor-positive (HR+) breast cancer. Molecular mechanisms associated with endocrine resistance include adaptive cross-talk between the estrogen receptor and the fibroblast growth factor receptor (FGFR). Up to 8% of HR+/ human epidermal growth factor receptor 2 negative (HER2–) breast cancer patients have amplification of the FGFR1 gene, which is associated with resistance to endocrine therapy. In preclinical models, resistance to endocrine therapy can be overcome via FGFR1 inhibition. Dovitinib is a potent oral inhibitor of receptor tyrosine kinases, including FGFR, vascular endothelial growth factor receptor (VEGFR), and platelet derived growth factor receptor (PDGFR), that demonstrated antitumor activity in heavily pretreated breast cancer patients with FGF-pathway amplification (FGFR1, FGFR2, or ligand FGF3; Andre et al, ASCO 2011). Dovitinib may reverse resistance to endocrine therapy related to FGF-pathway amplification and may also inhibit angiogenesis, which plays an essential role in breast cancer development. Dovitinib is studied here in combination with fulvestrant to determine if it can improve outcomes in postmenopausal patients with endocrine resistant HER2−/HR+ breast cancer.

Methods: This is a multicenter, randomized, double-blind, placebo-controlled, phase II trial that will enroll postmenopausal HER2–/HR+ locally advanced or metastatic breast cancer patients (N ≈ 150) progressing within 12 months of completion of adjuvant endocrine therapy or after ≤ 1 prior endocrine therapy in the advanced setting. Patients prospectively undergo molecular screening to enrich for FGF amplification (FGFR1, FGFR2, or FGF3 amplification by qualitative polymerase chain reaction (qPCR); 45 amplified and 30 nonamplified patients per arm). Patients are randomized 1:1 (stratified by FGF-amplification and presence of visceral disease) to receive fulvestrant intramuscularly (500 mg q4w [with an additional dose 2 weeks after the initial dose]) in combination with oral dovitinib (500 mg, 5 days on/2 days off) or placebo until disease progression, unacceptable toxicity, death or discontinuation due to any reason (eg, withdrawal). Crossover is not permitted. The primary endpoint is progression-free survival, with tumor assessments performed q8w. Secondary endpoints include overall response rate per RECIST v1.1, duration of response, overall survival, Eastern Cooperative Oncology Group performance status and patient-reported outcome scores over time, and safety. Additionally, the pharmacodynamic effect of dovitinib on FGFR-associated angiogenic pathways in tumor specimens and potential predictive biomarkers of response to dovitinib will be explored.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr OT2-2-03.

Abstract P1-13-04: Optimal duration of adjuvant chemotherapy for high risk node negative breast cancer patients: 6-year results of the prospective randomized phase III trial PACS 05

BACKGROUND: In 2000, the NIH Consensus meeting concluded that 4 to 6 cycles of adjuvant chemotherapy appeared to provide an optimal benefit; So, we underwent a prospective randomized trial comparing 4 and 6 cycles of FEC 100 (JCO 2005; 23: 2686–2693) for high risk node negative breast cancer patients.

METHODS: This study enrolled 18–65 y women with operable breast cancer, without axillary lymph node involvement, or presence of isolated tumor cells, with size superior to 1 cm and another poor prognostic factor: T &gt; 2 cm, HR –, SBR grade II or III, age &lt; 35 y.

After adequate breast surgery and axillary lymph node dissection or sentinel node technique, they were randomized between arm A, 6 cycles of FEC 100, and arm B, 4 cycles, every three weeks. The local regional treatment was completed following usual recommendations. All HR+ patients received hormonal therapy for 5 years. After August 2005, patients with HER2+ tumors were excluded from this study.

The primary end point was PFS at 5 years. This study was powered to detect a 6% difference in favour of 6 cycles.

Between August 2002 and September 2006, 1516 patients were randomized; 1515 are analysed in ITT. Three patients in the B group did not receive any chemotherapy. There is no significant difference between the two arms for tumor and patient characteristics.

RESULTS At a median follow-up of 73 months we observed regarding PFS a low event rate, 197 for the entire population (13%) 91 in arm A median PFS, vs. 106 in arm B median PFS, without any difference between the two groups for DFS, DDFS, local relapse, overall survival. There was no unexpected toxicity. In the arm A we observed more grade III and IV neutropenia, without congestive heart failure.

CONCLUSION At a follow-up of 73 months, we observed a low relapse rate, with no significant difference between the two arms. Duration of FEC100 does not induce different outcomes in this population. Question of length of adjuvant treatment is still open with and without taxanes.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-13-04.

Abstract P3-12-01: Serum biomarkers identification using quantitative proteomics in patients (pts) with untreated brain metastases from HER2-positive breast cancer receiving capecitabine (C) and lapatinib (L) (UNICANCER LANDsCAPE trial)

Background: The LANDsCAPE phase II study showed that C+L had a significant antitumor activity in previously untreated brain metastases (BM) from HER2-positive breast cancer (BC), with a central nervous system-objective response rate (CNS-ORR) of 67% and a median time to whole-brain radiotherapy (WBRT) of 8.3 months (43 analysed pts). Thus initial C+L combination might be a viable alternative to immediate WBRT in this setting. In this study, serum samples were collected before and during treatment for proteomic-based approaches to identify predictive biomarkers of treatment response.

Methods: Baseline (BL) and day 21 (D21) serum samples from highly responsive (R, CNS lesions -volumetric response ≥ 75%, n=6) and non-responsive (NR, CNS-stable or progressive disease, n=6) pts were subjected to isobaric Tag for Relative and Absolute Quantification (iTRAQ)-based proteomics. Samples from each condition were pooled to constitute 4 independent mixes ((BL-R, D21-R, BL-NR and D21-NR). Each of them underwent immuno-depletion of highly abundant proteins, concentration, reduction, alkylation and tryptic digestion. Then, each mix was fractionated and subjected to iTRAQ identification and quantitation using nano-liquid chromatography (LC) and electrospray ionisation (ESI)-orbitrap tandem mass spectrometry (MS/MS) (LTQ-orbitrap, Thermofisher). Differentially expressed proteins were analysed using IPA (Ingenuity® Systems) to highlight biological functions and signalling pathways that were most significantly enriched.

Results: iTRAQ-based measurements identified serum proteins with significant (fold-change &gt; 1.5 and p-value &lt; 0.05) differential expression between BL and D21, in R- (n = 38 proteins) and NR- pts (n = 18 proteins). At baseline, 30 proteins were differentially expressed between R-and NR-pts. Among the most differentially expressed proteins, some had been previously described as involved in cancer metastases (between BL and D21: tenascin C, neuropilin-1, Serpin A1, Cathepsin S, prostaglandin D2 synthase, melanoma cell adhesion molecules, procollagen C-endopeptidase enhancer; between R and NR: carnosine dipeptidase 1, endothelial protein C receptor, matrix metallopeptidase 9, cystatin C, lumican, plexin B2, Insulin-like growth factor binding protein acid labile subunit, pro-platelet basic protein, cadherin 5, Protein S). Proteins with differential expression during treatment were involved in various biological processes, including lipid metabolism, small molecule biochemistry, molecular transport, gene expression, cellular growth and proliferation, cellular movement and cancer, as well as various canonical pathways such as acute phase response signalling, LXR/RXR activation and complement system. Interestingly, and as opposed to NR-pts, R-pts specifically showed an overall increase in proteins of acute phase response, with a significant decrease in C-reactive protein (CRP).

Conclusion: iTRAQ-based quantitative proteomics identify serum proteins that could predict the therapeutic response to C+L combination in untreated BM from HER2-positive BC. If validated, such biomarkers may help to select the best therapeutic strategy in this setting.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-12-01.