Benefit from adjuvant tamoxifen therapy in primary breast cancer patients according oestrogen receptor, progesterone receptor, EGF receptor and HER2 status

Biomarkers for the clinical management of breast cancer: international perspective

The higher incidence of breast cancer in developed countries has been tempered by reductions in mortality, largely attributable to mammographic screening programmes and advances in adjuvant therapy. Optimal systemic management requires consideration of clinical, pathological and biological parameters. Oestrogen receptor alpha (ERα), progesterone receptor (PgR) and human epidermal growth factor receptor 2 (HER2) are established biomarkers evaluated at diagnosis, which identify cardinal subtypes of breast cancer. Their prognostic and predictive utility effectively guides systemic treatment with endocrine, anti-HER2 and chemotherapy. Hence, accurate and reliable determination remains of paramount importance. However, the goals of personalized medicine and targeted therapies demand further information regarding residual risk and potential benefit of additional treatments in specific circumstances. The need for biomarkers which are fit for purpose, and the demands placed upon them, is therefore expected to increase. Technological advances, in particular high-throughput global gene expression profiling, have generated multi-gene signatures providing further prognostic and predictive information. The rational integration of routinely evaluated clinico-pathological parameters with key indicators of biological activity, such as proliferation markers, also provides a ready opportunity to improve the information available to guide systemic therapy decisions. The additional value of such information and its proper place in patient management is currently under evaluation in prospective clinical trials. Expanding the utility of biomarkers to lower resource settings requires an emphasis on cost effectiveness, quality assurance and possible international variations in tumor biology; the potential for improved clinical outcomes should be justified against logistical and economic considerations.

Phase II study assessing lapatinib added to letrozole in patients with progressive disease under aromatase inhibitor in metastatic breast cancer-Study BES 06

This trial evaluated the effect of adding lapatinib to letrozole after clinical resistance to aromatase inhibitor (IA) treatment in hormone receptor-positive metastatic breast cancer. Postmenopausal women received daily letrozole plus lapatinib (1,500 mg). The primary end point was objective rate response (ORR) at week 12. Secondary objectives included time to response, duration of response, clinical benefit (CB), progression-free survival (PFS), overall survival, and safety. Twenty-four human epidermal growth factor receptor 2 (HER2)-negative patients were included with secondary resistance to IA. ORR at 12 weeks was 4 % (95 % confidence interval (CI), 0.7-20). Stable and progression diseases were reported in 25 % (95 % CI, 12-45) and 71 % (95 % CI, 51-85) of cases, respectively. At 24 weeks, the ORR increased to 8 %. CB was 21 % (95 % CI, 9-40). At a median follow-up of 27 months, median PFS was 3.4 months (95 % CI, 2.8-5.4). Grade 3 or 4 adverse events were rarely reported. No clinical cardiac toxicity was observed. Lapatinib was discontinued in two patients due to severe diarrhea. This trial was prematurely closed due to low recruitment. These preliminary results suggest that the addition of lapatinib to letrozole has a favorable safety profile and could overcome tumoral resistance to letrozole among HER2-negative tumors.

Molecular pathways and molecular imaging in breast cancer: an update

Breast cancer is a heterogenic cancer being characterized by a variability of somatic mutations and in particular by different receptor expressions, such as estrogen, progesterone and human epidermal receptor. These phenotype characteristics play a crucial role in determining tumour response to various chemotherapies and other treatments and in the development of resistance to therapies. Positron emission tomography (PET) as a nuclear medicine technique, has recently demonstrated the advantages in determining the severity of disease and in evaluating the efficacy of treatments in a variety of neoplasm, including breast cancer. Because this procedure is able to pinpoint molecular activity within the body, it offers the potential to identify disease in its earliest stages as well as a patient's immediate response to therapeutic interventions in a non-invasive way. In this paper we performed an extended view about the correlation between molecular factors of breast cancer and PET tracers; in particular, we focalized our attention on their possible advantages in terms of 1) early detection of primary or recurrent cancer; 2) as a guide for target therapies and 3) for the evaluation of response to specific and now-available molecular treatments.

Immunohistochemical profile and clinical-pathological variables in breast cancer

OBJECTIVE

To describe the main characteristics of women with breast cancer, according to the immunohistochemical profile.

METHODS

The population comprised a hospital cohort, consisting of women diagnosed with breast cancer between 2003 and 2005 (n = 601) and treated at a referral center for cancer care in Juiz de Fora, MG, Brazil. Only 397 women who had complete immunohistochemistry analysis were selected. To define the groups according to the immunohistochemical profile, the assessment of estrogen and progesterone receptors, Ki-67 cell proliferation index, and overexpression of human epidermal growth factor receptor 2 (HER2) was chosen. According to the different phenotypes, five subtypes were defined: luminal A, luminal B HER2 negative, luminal B HER2 positive, triple negative, and HER2 overexpression.

RESULTS

Most patients were white (80.7%) and post-menopausal (64.9%), with a mean age of 57.4 years (± 13.5). At diagnosis, 57.5% had tumor size > 2.0 cm, and 41.7% had lymph node involvement. The most common subtypes were luminal B - HER2 negative (41.8%) and triple negative (24.2%). In the luminal A subtype, 72.1% of patients were post-menopausal, while the highest percentage of premenopausal women were observed in the luminal B - HER2 positive and triple negative subtypes (45.2% and 44.2%, respectively). A higher frequency of tumors > 2.0 cm and lymph node involvement was observed in triple negative and HER2 positive subtypes.

CONCLUSION

This study allowed the distribution assessment of the main clinical and pathological characteristics and those related to health services in a cohort of Brazilian women with breast cancer, according to the immunohistochemical tumor subtypes.

Activation of Akt, mTOR, and the estrogen receptor as a signature to predict tamoxifen treatment benefit

The frequent alterations of the PI3K/Akt/mTOR-growth signaling pathway are proposed mechanisms for resistance to endocrine therapy in breast cancer, partly through regulation of estrogen receptor α (ER) activity. Reliable biomarkers for treatment prediction are required for improved individualized treatment. We performed a retrospective immunohistochemical analysis of primary tumors from 912 postmenopausal patients with node-negative breast cancer, randomized to either tamoxifen or no adjuvant treatment. Phosphorylated (p) Akt-serine (s) 473, p-mTOR-s2448, and ER phosphorylations-s167 and -s305 were evaluated as potential biomarkers of prognosis and tamoxifen treatment efficacy. High expression of p-mTOR indicated a reduced response to tamoxifen, most pronounced in the ER+/progesterone receptor (PgR) + subgroup (tamoxifen vs. no tamoxifen: hazard ratio (HR), 0.86; 95 % confidence interval (CI), 0.31–2.38; P = 0.78), whereas low p-mTOR expression predicted tamoxifen benefit (HR, 0.29; 95 % CI, 0.18–0.49; P = 0.000002). In addition, nuclear p-Akt-s473 as well as p-ER at -s167 and/or -s305 showed interaction with tamoxifen efficacy with borderline statistical significance. A combination score of positive pathway markers including p-Akt, p-mTOR, and p-ER showed significant association with tamoxifen benefit (test for interaction; P = 0.029). Cross-talk between growth signaling pathways and ER-signaling has been proposed to affect tamoxifen response in hormone receptor-positive breast cancer. The results support this hypothesis, as an overactive pathway was significantly associated with reduced response to tamoxifen. A clinical pre-treatment test for cross-talk markers would be a step toward individualized adjuvant endocrine treatment with or without the addition of PI3K/Akt/mTOR pathway inhibitors.

Prognostic significance of progesterone receptor-positive tumor cells within immunohistochemically defined luminal A breast cancer

PURPOSE

Current immunohistochemical (IHC)-based definitions of luminal A and B breast cancers are imperfect when compared with multigene expression-based assays. In this study, we sought to improve the IHC subtyping by examining the pathologic and gene expression characteristics of genomically defined luminal A and B subtypes.

PATIENTS AND METHODS

Gene expression and pathologic features were collected from primary tumors across five independent cohorts: British Columbia Cancer Agency (BCCA) tamoxifen-treated only, Grupo Español de Investigación en Cáncer de Mama 9906 trial, BCCA no systemic treatment cohort, PAM50 microarray training data set, and a combined publicly available microarray data set. Optimal cutoffs of percentage of progesterone receptor (PR) -positive tumor cells to predict survival were derived and independently tested. Multivariable Cox models were used to test the prognostic significance.

RESULTS

Clinicopathologic comparisons among luminal A and B subtypes consistently identified higher rates of PR positivity, human epidermal growth factor receptor 2 (HER2) negativity, and histologic grade 1 in luminal A tumors. Quantitative PR gene and protein expression were also found to be significantly higher in luminal A tumors. An empiric cutoff of more than 20% of PR-positive tumor cells was statistically chosen and proved significant for predicting survival differences within IHC-defined luminal A tumors independently of endocrine therapy administration. Finally, no additional prognostic value within hormonal receptor (HR) -positive/HER2-negative disease was observed with the use of the IHC4 score when intrinsic IHC-based subtypes were used that included the more than 20% PR-positive tumor cells and vice versa.

CONCLUSION

Semiquantitative IHC expression of PR adds prognostic value within the current IHC-based luminal A definition by improving the identification of good outcome breast cancers. The new proposed IHC-based definition of luminal A tumors is HR positive/HER2 negative/Ki-67 less than 14%, and PR more than 20%.

Clinical and biologic features of triple-negative breast cancers in a large cohort of patients with long-term follow-up

Studies on well characterized, large populations of estrogen receptor (ER)/progesterone receptor (PgR)/HER2-negative [triple-negative (TN)] breast cancer (BC) patients with long-term follow-up are lacking. In this study, we analyze clinical outcomes of TN BC and implications of epidermal growth factor receptor (EGFR) expression. Clinical and biologic features, time to first recurrence (TTFR), and overall survival (OS) were compared in 253 TN versus 1,036 ER positive, PgR positive, HER2-negative [estrogen-driven (ED)] BC. Compared to ED, TN tumors were larger (p = 0.02), more proliferative (high S-phase 54 vs. 17 %, p < 0.0001), more aneuploid (64 vs. 43 %, p < 0.0001) and more likely EGFR positive (≥10 fmol/mg by radioligand-binding assay, 49 vs. 7 %, p < 0.0001). Among TN, EGFR-positive BC were larger (p = 0.0018), more proliferative (p < 0.0001), and more aneuploid, (p < 0.0001) than EGFR-negative BC. Adjuvant-treated TN patients had shorter TTFR (p = 0.0003), and OS (p = 0.0017), than ED patients. However, in untreated patients, no differences in TTFR and OS were observed at 8 years median follow-up. Among TN patients, EGFR expression was not associated with worse outcome. TN tumors have a worse outcome in systemically treated patients but not in untreated patients. EGFR expression, does not predict for worse long-term survival.

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.

Adding hormonal therapy to chemotherapy and trastuzumab improves prognosis in patients with hormone receptor-positive and human epidermal growth factor receptor 2-positive primary breast cancer

Adjuvant hormonal therapy for hormone receptor (HR)-positive primary breast cancer patients and a human epidermal growth factor receptor 2 (HER2)-targeted agent for HER2-positive primary breast cancer patients are standard treatment. However, it is not well known whether adding hormonal therapy to the combination of preoperative or postoperative chemotherapy and HER2-targeted agent contributes any additional clinical benefit in patients with HR-positive/HER2-positive primary breast cancer regardless of cross-talk between HR and HER2. We retrospectively reviewed records from 897 patients with HR-positive/HER2-positive primary breast cancer with clinical stage I-III disease who underwent surgery between 1988 and 2009. We determined the overall survival (OS) and disease-free survival (DFS) rates according to whether they received hormonal therapy or not and according to the type of hormonal therapy, tamoxifen and aromatase inhibitor, they received. The median followup time was 52.8 months (range 1-294.6 months). Patients who received hormonal therapy with chemotherapy and trastuzumab (n = 128) had significantly higher OS and DFS rates than did those who received only chemotherapy and trastuzumab (n = 46) in log-rank analysis (OS 96.1 vs. 87.0 %, p = 0.023, DFS 86.7 vs. 78.3 %, p = 0.029). There was no statistical difference in OS or DFS between those given an aromatase inhibitor and those given tamoxifen. In multivariate analysis, receiving hormonal therapy in addition to the combination of chemotherapy and trastuzumab was the sole independent prognostic factor for DFS (hazard ratio 0.446; 95 % CI 0.200-0.992; p = 0.048), and there was a similar trend in OS. Our study supported that hormonal therapy, whether in the form of an aromatase inhibitor or tamoxifen, confers a survival benefit when added to chemotherapy and trastuzumab in patients with HR-positive/HER2-positive primary breast cancer. Adjuvant treatment without hormonal therapy is inferior for this patient population.

Efficacy and pharmacogenomic biomarkers in breast cancer

In patients with breast cancer, a number of biomarkers, such as estrogen receptor, progesterone receptor and HER2, are part of routine work-up and used to guide endocrine, cytotoxic and HER2-targeted treatment. Interaction among these markers may also impact on treatment response and is being investigated. Multigene assays have reached varying levels of validation and clinical use as predictive biomarkers of cytotoxic therapy in specific clinical situations. A number of pharmacogenomic biomarkers based on germline polymorphisms have reached some degree of validation for predicting variation in treatment response and treatment-associated adverse effects. The challenge of validating biomarkers will be exacerbated as the cost of nucleic acid sequencing rapidly declines and more potential biomarkers emerge. New, carefully designed approaches will be needed to address this issue and realize the potential of biomarkers in breast cancer.

Inhibition of the AKT/mTOR and erbB pathways by gefitinib, perifosine and analogs of gonadotropin-releasing hormone I and II to overcome tamoxifen resistance in breast cancer cells

Endocrine resistance in breast cancer remains a major clinical problem and is caused by crosstalk mechanisms of growth factor receptor cascades, such as the erbB and PI3K/AKT pathways. The possibilities a single breast cancer cell has to achieve resistance are manifold. We developed a model of 4-hydroxy-tamoxifen (OHT)‑resistant human breast cancer cell lines and compared their different expression patterns, activation of growth factor receptor pathways and compared cells by genomic hybridization (CGH). We also tested a panel of selective inhibitors of the erbB and AKT/mTOR pathways to overcome OHT resistance. OHT‑resistant MCF-7-TR and T47D-TR cells showed increased expression of HER2 and activation of AKT. T47D-TR cells showed EGFR expression and activated MAPK (ERK-1/2), whereas in resistant MCF-7-TR cells activated AKT was due to loss of CTMP expression. CGH analyses revealed remarkable aberrations in resistant sublines, which were predominantly depletions. Gefitinib inhibited erbB signalling and restored OHT sensitivity in T47D-TR cells. The AKT inhibitor perifosine restored OHT sensitivity in MCF-7-TR cells. All cell lines showed expression of receptors for gonadotropin-releasing hormone (GnRH) I and II, and analogs of GnRH-I/II restored OHT sensitivity in both resistant cell lines by inhibition of erbB and AKT signalling. In conclusion, mechanisms to escape endocrine treatment in breast cancer share similarities in expression profiling but are based on substantially different genetic aberrations. Evaluation of activated mediators of growth factor receptor cascades is helpful to predict response to specific inhibitors. Expression of GnRH-I/II receptors provides multi-targeting treatment strategies.

Activated HER-receptors in predicting outcome of ER-positive breast cancer patients treated with adjuvant endocrine therapy

The four human epidermal growth factor receptors (HER1-4) are involved in growth stimulation and may play a role in endocrine resistance. The receptors form dimers, leading to activation by mutual phosphorylation. Our purpose was to explore the role of the activated receptors (pHER1, pHER2, pHER3) in endocrine treated breast cancer in terms of co-expression and association with disease-free survival (DFS) in 1062 patients with ER-positive tumors. Furthermore, HER2 amplification was evaluated. We found positive associations between the phosphorylated receptors. pHER1 and pHER3 were co-expressed with one or two of the other activated receptors in 85% and 89% of tumors, respectively, whereas pHER2 was co-expressed with the other activated receptors in 54% of tumors. Except for HER2, which was associated with poor prognosis, none of the remaining markers were associated with DFS. However, frequent co-expression indicates a role of the other HER-family members in activation of HER2.

Can predictive biomarkers in breast cancer guide adjuvant endocrine therapy?

Personalized medicine for oestrogen receptor-α (ERα)-positive breast cancer requires predictive biomarkers for broad endocrine resistance as well as biomarkers capable of predicting resistance to a specific agent. In addition, biomarkers could be used to select patients that might benefit from the addition of treatments that do not target ERα. However, biomarker identification studies seem to be far from consistent and identified biomarkers seldom face an introduction into clinical practice. Importantly, most of the studies that seek to identify biomarkers have been performed using material from consecutive series of patients treated with tamoxifen (the most commonly prescribed ERα antagonist). Consequently, the predictive value of any biomarker identified is confounded by its prognostic value. Another important issue is the lack of differentiation between premenopausal and postmenopausal patients with breast cancer. The hormonal environment of a tumour in patients who are premenopausal is intrinsically distinct from those arising in postmenopausal women. Biomarkers of different biological mechanisms might enable the prediction of either broad endocrine resistance or resistance to a specific agent in each of these patient subtypes. Ultimately, improvements to study design are needed to establish the clinical validity of the most promising biomarkers to predict benefit from endocrine therapy.

Semi-quantitative immunohistochemical assay versus oncotype DX(®) qRT-PCR assay for estrogen and progesterone receptors: an independent quality assurance study

Estrogen receptor (ER) status is a strong predictor of response to hormonal therapy in breast cancer patients. Presence of ER and level of expression have been shown to correlate with time to recurrence in patients undergoing therapy with tamoxifen or aromatase inhibitors. Risk reduction is also known to occur in ER-negative, progesterone receptor (PR)-positive patients treated with hormonal therapy. Since the 1990s, immunohistochemistry has been the primary method for assessing hormone receptor status. Recently, as a component of its oncotype DX(®) assay, Genomic Health began reporting quantitative estrogen and PR results determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). As part of an ongoing quality assurance program at our institution, we reviewed 464 breast cancer cases evaluated by both immunohistochemistry and oncotype DX(®) assay for estrogen and PR. We found good correlation for ER status between both assays (98.9% concordance), with immunohistochemistry being slightly more sensitive. Concordance for PR was 94.2% between immunohistochemistry and qRT-PCR with immunohistochemistry again more sensitive than RT-PCR. The results also showed linear correlation between immunohistochemistry H-scores and qRT-PCR expression values for ER (correlation coefficient of 0.579), and PR (correlation coefficient of 0.685). Due to the higher sensitivity of hormone receptor immunohistochemistry and additional advantages (ie preservation of morphology, less expensive, faster, more convenient), we conclude immunohistochemistry is preferable to qRT-PCR for determination of estrogen and PR expression.

Preclinical and clinical studies of estrogen deprivation support the PDGF/Abl pathway as a novel therapeutic target for overcoming endocrine resistance in breast cancer

Introduction

The majority of breast tumors at primary diagnosis are estrogen receptor positive (ER+). Estrogen (E) mediates its effects by binding to the ER. Therapies targeting the estrogenic stimulation of tumor growth reduce mortality from ER+ breast cancer. However, resistance remains a major clinical problem.

Methods

To identify molecular mechanisms associated with resistance to E-deprivation, we assessed the temporal changes in global gene expression during adaptation to long-term culture of MCF7 human breast cancer cells in the absence of estradiol (E2), long term estrogen deprived (LTED), that leads to recovery of proliferative status and models resistance to an aromatase inhibitor (AI). The expression levels of proteins were determined by western blotting. Proliferation assays were carried out using the dual platelet derived growth factor receptor (PDGFR)/Abelson tyrosine kinase (Abl) inhibitor nilotinib. Luciferase reporter assays were used to determine effects on ER-mediated transactivation. Changes in recruitment of cofactors to the gene regulated by estrogen in breast cancer 1 (GREB1) promoter were determined by chromatin immunoprecipitation (ChIP). Gene expression data were derived from 81 postmenopausal women with ER+ BC pre-treatment and at two-weeks post-treatment with single agent anastrozole in a neoadjuvant trial.

Results

The PDGF/Abl canonical pathway was significantly elevated as early as one week post E-deprivation (P = 1.94 E-04) and this became the top adaptive pathway at the point of proliferative recovery (P = 1.15 E-07). Both PDGFRβ and Abl protein levels were elevated in the LTED cells compared to wild type (wt)-MCF7 cells. The PDGF/Abl tyrosine kinase inhibitor nilotinib, suppressed proliferation in LTED cells in the presence or absence of E. Nilotinib also suppressed ER-mediated transcription by destabilizing the ER and reducing recruitment of amplified in breast cancer-1 (AIB1) and the CREB binding protein (CBP) to the promoter of the E-responsive gene GREB1. High PDGFRβ in primary ER+ breast cancer of 81 patients prior to neoadjuvant treatment with an AI was associated with poorer antiproliferative response. Additionally PDGFRβ expression increased after two weeks of AI therapy (1.25 fold, P = 0.003).

Conclusions

These preclinical and clinical data indicate that the PDGF/Abl signaling pathway merits clinical evaluation as a therapeutic target with endocrine therapy in ER+ breast cancer.

A five-gene model predicts clinical outcome in ER+/PR+, early-stage breast cancers treated with adjuvant tamoxifen

Primary breast carcinomas expressing both estrogen and progesterone receptors are most likely to respond to tamoxifen therapy, especially in patients with early-stage lesions. However, certain patients exhibit clinicopathologic features suggesting good prognosis relapse within 10 years, justifying a search for biomarkers identifying patients at risk for recurrence. Nine candidate genes associated with estrogen signaling were selected from microarray studies and combined with those for conventional biomarkers (ESR1, PGR, ERBB2). Expression of this 12-gene subset was analyzed by RT-qPCR in frozen tissue specimens from 60 early-stage, estrogen receptor (ER)+/progestin receptor (PR)+ breast cancers from patients treated with adjuvant tamoxifen. A multivariate model was created by Cox regression using a training data set and applied to an independent validation set. A five-gene model was developed from the training set (n = 36) that exhibited significant correlations with both relapse-free and overall survival. Applying this model to Kaplan-Meier regression, patients were separated into low-risk (100% relapse-free at 150 months) and high-risk (60% relapse-free at 150 months) groups (P = 0.03). When this model was applied to the validation set (n = 24), similar risk stratification was achieved for both relapse-free and overall survival (P = 0.01 and 0.04, respectively). We developed a five-gene model composed of PgR, BCL2, ERBB4 JM-a, RERG, and CD34 that identified early-stage, ER+/PR+ breast cancers in patients treated with tamoxifen that relapsed, although they exhibited clinicopathologic features suggesting good prognosis. Within this multivariate model, increased expression of PgR, ERBB4 JM-a, RERG, and CD34 was associated with increased survival, while increased expression of BCL2 was associated with decreased survival.

Assessment of progesterone receptors in breast carcinoma by PET with 21-18F-fluoro-16α,17α-[(R)-(1'-α-furylmethylidene)dioxy]-19-norpregn-4-ene-3,20-dione

This first-in-human study was designed to evaluate the safety and dosimetry of the progesterone analog 21-(18)F-fluoro-16α,17α-[(R)-(1'-α-furylmethylidene)dioxy]-19-norpregn-4-ene-3,20-dione ((18)F-FFNP), as well the feasibility of imaging tumor progesterone receptors (PRs) by PET in breast cancer.

METHODS

Women with breast cancer underwent PET with (18)F-FFNP. Tumor (18)F-FFNP uptake was assessed semiquantitatively by determining maximum standardized uptake value and tumor-to-normal breast (T/N) activity ratio and by Logan graphical analysis. The PET results were correlated with estrogen receptor (ER) and PR status, assessed by in vitro assays of the tumor tissue. The biodistribution of (18)F-FFNP was measured in patients by whole-body PET, and human dosimetry was estimated.

RESULTS

Twenty patients with 22 primary breast cancers (16 PR-positive [PR+] and 6 PR-negative [PR-]) were evaluated. Tumor maximum standardized uptake value was not significantly different in PR+ and PR- cancers (mean ± SD, 2.5 ± 0.9 vs. 2.0 ± 1.3, P = 0.386), but the T/N ratio was significantly greater in the PR+ cancers (2.6 ± 0.9 vs. 1.5 ± 0.3, P = 0.001). In addition, there was a significant correlation between distribution volume ratio and T/N ratio (r = 0.89; P = 0.001) but not between distribution volume ratio and either PR status or standardized uptake value, likely because of small sample size. On the basis of whole-body PET data in 12 patients, the gallbladder appeared to be the dose-limiting organ, with an average radiation dose of 0.113 mGy/MBq. The whole-body dose was 0.015 mGy/MBq, and the effective dose was 0.020 mSv/MBq. No adverse effects of (18)F-FFNP were encountered.

CONCLUSION

(18)F-FFNP PET is a safe, noninvasive means for evaluating tumor PRs in vivo in patients with breast cancer. The relatively small absorbed doses to normal organs allow for the safe injection of up to 440 MBq of (18)F-FFNP.

Observer prediction of HER2 amplification in HercepTest 2+ breast cancers as a potential audit instrument

AIMS

Correct assignment of human epidermal growth factor receptor 2 (HER2) status in breast cancer is important. Indeterminate (2+) HER2 immunohistochemistry (IHC) is usually resolved by FISH for HER2 gene amplification. It was hypothesised that predicting HER2 amplification in IHC 2+ cases could improve audit of HER2 IHC and its interpretation.

METHODS AND RESULTS

One observer (J. J. G.) interpreted 4343 assessable HercepTests on consecutive breast cancers from the West of Scotland over 45 consecutive months during 2007-2010, with 2+ cases classified prospectively as 'probably amplified', 'possibly amplified' or 'probably not amplified' prior to FISH. A HER2 to chromosome 17 FISH ratio >2 was taken to define HER2 amplification. There were 265 3+ cases (6.1%) and 883 2+ cases (20.3%). Of 187 'probably amplified' 2+ cases, 166 (88.8%) were amplified, as were 90 (37.8%) of 238 'possibly amplified' 2+ cases. Of 458 'probably not amplified' but still 2+ cases, 59 (12.8%) were in fact amplified (overall χ2 333.89, df 2, P < 0.0001). In total, 580 of 4343 (13.4%) cancers were HER2-positive (265 3+ by IHC and 315 2+ and HER2 amplified).

CONCLUSIONS

Breast cancers HER2-indeterminate (2+) by HercepTest IHC can be strongly separated into those probably HER2 amplified, a core indeterminate group and those probably not HER2 amplified. The percentage of HER2 amplified cases in each category is proposed as an instrument for comparison of HER2 IHC and its interpretation between laboratories and observers.

GPER mediates the Egr-1 expression induced by 17β-estradiol and 4-hydroxitamoxifen in breast and endometrial cancer cells

Early growth response-1 (Egr-1) is an immediate early gene involved in relevant biological events including the proliferation of diverse types of cell tumors. In a microarray analysis performed in breast cancer cells, 17β-estradiol (E2) and the estrogen receptor antagonist 4-hydroxitamoxifen (OHT) up-regulated Egr-1 through the G protein-coupled receptor named GPR30/GPER. Hence, in this study, we aimed to provide evidence regarding the ability of E2, OHT and the selective GPER ligand G-1 to regulate Egr-1 expression and function through the GPER/EGFR/ERK transduction pathway in both Ishikawa (endometrial) and SkBr3 (breast) cancer cells. Interestingly, we demonstrate that Egr-1 is involved in the transcription of genes regulating cell proliferation like CTGF and cyclin D1 and required for the proliferative effects induced by E2, OHT, and G-1 in both Ishikawa and SkBr3 cells. In addition, we show that GPER mediates the expression of Egr-1 also in carcinoma-associated fibroblasts (CAFs). Our data suggest that Egr-1 may represent an important mediator of the biological effects induced by E2 and OHT through GPER/EGFR/ERK signaling in breast and endometrial cancer cells. The results obtained in CAFs provide further evidence regarding the potential role exerted by the GPER-dependent Egr-1 up-regulation in tumor development and progression. Therefore, Egr-1 may be included among the bio-markers of estrogen and antiestrogen actions and may be considered as a further therapeutic target in both breast and endometrial tumors.

Advantages of adjuvant chemotherapy for patients with triple-negative breast cancer at Stage II: usefulness of prognostic markers E-cadherin and Ki67

Introduction

Triple-negative breast cancer (TNBC), which is characterized by negativity for estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2 (HER2), is a high risk breast cancer that lacks specific targets for treatment selection. Chemotherapy is, therefore, the primary systemic modality used in the treatment of this disease, but reliable parameters to predict the chemosensitivity of TNBC have not been clinically available.

Methods

A total of 190 TNBC patients who had undergone a curative resection of a primary breast cancer were enrolled. The adjuvant chemotherapy was performed for 138 (73%) of 190 TNBC cases; 60 cases had an anthracyclin-based regimen and 78 a 5-fluorouracil-based regimen. The prognostic value of E-cadherin, Ki67 and p53 expression in the outcome of TNBC patients with adjuvant chemotherapy was evaluated by immunohistochemistry.

Results

The adjuvant therapy group, especially those with Stage II TNBC, had a more favorable prognosis than the surgery only group (P = 0.0043), while there was no significant difference in prognosis between the anthracyclin-based regimen and 5-fluorouracil-based regimen. Patients with E-cadherin-negative and Ki67-positive expression showed significantly worse overall survival time than those with either E-cadherin-positive or Ki67-negative expression (P < 0.001). Multivariate analysis showed that the combination of E-cadherin-negative and Ki67-positive expression was strongly predictive of poor overall survival (P = 0.004) in TNBC patients receiving adjuvant chemotherapy. In contrast, p53 status was not a specific prognostic factor.

Conclusions

Adjuvant therapy is beneficial for Stage II TNBC patients. The combination of E-cadherin and Ki67 status might be a useful prognostic marker indicating the need for adjuvant chemotherapy in Stage II TNBC patients.

Breast cancer stem cells and their role in resistance to endocrine therapy

Developmentally, tumours can be viewed as aberrant versions of normal tissues. For example, tumours often retain differentiation markers of their tissue of origin. In addition, there is evidence that they contain cancer stem-like cells (CSCs) that drive tumourigenesis. In this review, we summarise current evidence that breast CSCs may partially explain endocrine resistance in breast cancer. In normal breast, the stem cells are known to possess a basal phenotype and to be mainly oestrogen receptor-α-negative (ER-). If the hierarchy in breast cancer reflects this, the breast CSC may be endocrine resistant because it expresses very little ER and can only respond to treatment by virtue of paracrine signalling from neighbouring, differentiated ER+ tumour cells. Normal breast epithelial stem cells are regulated by the epidermal growth factor receptor and other growth factor receptor signals. The observed increase in growth factor receptor expression in endocrine-resistant breast cancers may reflect a bigger proportion of CSCs selected by endocrine therapies. There is evidence from a number of studies that breast CSCs are ER- and EGR+/HER2+, which would support this view. It is reported that CSCs express mesenchymal genes, which are suppressed by ER expression, further indicating the mutual exclusion between ER+ cells and the CSCs. As we learn more about CSCs, differentiation and the expression and functional activity of the ER in these cells in diverse breast tumour sub-types, it is hoped that our understanding will lead to new modalities to overcome the problem of endocrine resistance in the clinic.

Predictive and prognostic molecular markers for cancer medicine

Over the last 10 years there has been an explosion of information about the molecular biology of cancer. A challenge in oncology is to translate this information into advances in patient care. While there are well-formed routes for translating new molecular information into drug therapy, the routes for translating new information into sensitive and specific diagnostic, prognostic and predictive tests are still being developed. Similarly, the science of using tumor molecular profiles to select clinical trial participants or to optimize therapy for individual patients is still in its infancy. This review will summarize the current technologies for predicting treatment response and prognosis in cancer medicine, and outline what the future may hold. It will also highlight the potential importance of methods that can integrate molecular, histopathological and clinical information into a synergistic understanding of tumor progression. While these possibilities are without doubt exciting, significant challenges remain if we are to implement them with a strong evidence base in a widely available and cost-effective manner.

UK guidance document: treatment of metastatic breast cancer

Although there have been major improvements in the management of breast cancer, with a rapidly falling death rate despite an increasing incidence of the disease, metastatic breast cancer remains common and the cause of death in nearly 12 000 women annually in the UK. Numerous treatment options are available that either target the tumour or reduce the complications of the disease. Clinical decision making depends on knowledge of the extent and biology of the disease and available drug options, an understanding of the functional status, and also the wishes and expectations of the individual patient. In addition, the organisation of services and support of the patient are essential components of high-quality care. The National Institute for Health and Clinical Excellence (NICE) has produced guidelines for the treatment of advanced breast cancer, which in some areas have perhaps failed to appreciate the complexity of patient management. This guidance document aims to provide succinct practical advice on the treatment of metastatic breast cancer, highlight some limitations of the NICE guidelines, and provide suggestions for management where available data are limited.

In vivo magnetic resonance imaging of the estrogen receptor in an orthotopic model of human breast cancer

Histologic overexpression of the estrogen receptor α (ER) is a well-established prognostic marker in breast cancer. Noninvasive imaging techniques that could detect ER overexpression would be useful in a variety of settings where patients' biopsies are problematic to obtain. This study focused on developing, by in vivo MRI, strategies to measure the level of ER expression in an orthotopic mouse model of human breast cancer. Specifically, novel ER-targeted contrast agents based on pyridine-tetra-acetate-Gd(III) chelate (PTA-Gd) conjugated to 17β-estradiol (EPTA-Gd) or to tamoxifen (TPTA-Gd) were examined in ER-positive or ER-negative tumors. Detection of specific interactions of EPTA-Gd with ER were documented that could differentiate ER-positive and ER-negative tumors. In vivo competition experiments confirmed that the enhanced detection capability of EPTA-Gd was based specifically on ER targeting. In contrast, PTA-Gd acted as an extracellular probe that enhanced ER detection similarly in either tumor type, confirming a similar vascular perfusion efficiency in ER-positive and ER-negative tumors in the model. Finally, TPTA-Gd accumulated selectively in muscle and could not preferentially identify ER-positive tumors. Together, these results define a novel MRI probe that can permit selective noninvasive imaging of ER-positive tumors in vivo.

DHHC-7 and -21 are palmitoylacyltransferases for sex steroid receptors

Extranuclear sex steroid receptors require palmitoylation to traffic to the plasma membrane, where they activate signal transduction cascades. We identify DHHC-7 and -21 palmitoylacyltransferases as conserved enzymes for the three classes of sex steroid receptors.

Classical estrogen, progesterone, and androgen receptors (ERs, PRs, and ARs) localize outside the nucleus at the plasma membrane of target cells. From the membrane, the receptors signal to activate kinase cascades that are essential for the modulation of transcription and nongenomic functions in many target cells. ER, PR, and AR trafficking to the membrane requires receptor palmitoylation by palmitoylacyltransferase (PAT) protein(s). However, the identity of the steroid receptor PAT(s) is unknown. We identified the DHHC-7 and -21 proteins as conserved PATs for the sex steroid receptors. From DHHC-7 and -21 knockdown studies, the PATs are required for endogenous ER, PR, and AR palmitoylation, membrane trafficking, and rapid signal transduction in cancer cells. Thus the DHHC-7 and -21 proteins are novel targets to selectively inhibit membrane sex steroid receptor localization and function.

Estrogen receptor (ESR1) mRNA expression and benefit from tamoxifen in the treatment and prevention of estrogen receptor-positive breast cancer

PURPOSE

Several mechanisms have been proposed to explain tamoxifen resistance of estrogen receptor (ER) -positive tumors, but a clinically useful explanation for such resistance has not been described. Because the ER is the treatment target for tamoxifen, a linear association between ER expression levels and the degree of benefit from tamoxifen might be expected. However, such an association has never been demonstrated with conventional clinical ER assays, and the ER is currently used clinically as a dichotomous marker. We used gene expression profiling and ER protein assays to help elucidate molecular mechanism(s) responsible for tamoxifen resistance in breast tumors.

PATIENTS AND METHODS

We performed gene expression profiling of paraffin-embedded tumors from National Surgical Adjuvant Breast and Bowel Project (NSABP) trials that tested the worth of tamoxifen as an adjuvant systemic therapy (B-14) and as a preventive agent (P-1). This was a retrospective subset analysis based on available materials.

RESULTS

In B-14, ESR1 was the strongest linear predictor of tamoxifen benefit among 16 genes examined, including PGR and ERBB2. On the basis of these data, we hypothesized that, in the P-1 trial, a lower level of ESR1 mRNA in the tamoxifen arm was the main difference between the two study arms. Only ESR1 was downregulated by more than two-fold in ER-positive cancer events in the tamoxifen arm (P < .001). Tamoxifen did not prevent ER-positive tumors with low levels of ESR1 expression.

CONCLUSION

These data suggest that low-level expression of ESR1 is a determinant of tamoxifen resistance in ER-positive breast cancer. Strategies should be developed to identify, treat, and prevent such tumors.

Estrogen receptor positive operable breast cancer: does menopausal status impact on HER2 and progesterone receptor status?

PURPOSE

The objective of the present study was to determine whether progesterone receptor (PgR) and human epidermal growth factor receptor 2 (HER2) status differs by menopausal status in estrogen receptor (ER)-positive breast cancers.

PATIENTS AND METHODS

We retrospectively analyzed the clinicopathological data of 588 with operable ER(+) breast cancers patients. ER, HER2 and PgR expression in the tumor specimens were examined by immunohistochemistry. The relationship between different variables was assessed by Pearson's χ(2) and Fisher's exact probability tests in univariate analyses. Logistic regression was used for multivariate analyses of relationship between HER2 expression and selected clinicopathological characteristics. Maximum likelihood estimates of the odds ratio (OR) were obtained and 95% confidence intervals (CI) were calculated.

RESULTS

In the postmenopausal women with ER(+) tumors, HER2 was independently inversely associated with PgR expression (P = 0.017; OR 3.02; 95% CI 1.22-7.49). An ER(+)/PgR(-) tumor was 3.02 times more likely to express HER2 than an ER(+)/PgR(+) tumor in the postmenopausal women. However, an ER(+) tumor in the premenopausal patients failed to show an independent relationship between HER2 and PgR.

CONCLUSION

Menopausal status played a very important role in determining HER2 and PgR status in ER(+) breast cancer patients. HER2 was independently inversely associated with PgR only in the postmenopausal women with ER(+) breast cancers but not in the premenopausal ones.

The changing role of pathology in breast cancer diagnosis and treatment

Pathological examination has been the gold standard for diagnosis in cancer and its role has also included the elucidation of etiology, pathogenesis, clinicopathological correlation, and prognostication. The advent of newer technologies and the realization that breast cancer is heterogeneous has shifted the focus to prognostication, with increased attention being paid to the identification of morphological features and immunohistochemical markers of prognostic relevance. However, despite the massive efforts invested in the identification of immunohistochemical biomarkers in breast cancer the majority have not proven to be of value in multivariate analyses and only estrogen receptor, progesterone receptor, and Her2/neu expression have remained essential components of pathological examination. These 3 markers were initially employed for prognostication but their role in treatment also rendered them of predictive value. Newer molecular methods, especially high-throughput technologies, have shown that even morphologically similar subtypes of breast cancer can show molecular heterogeneity; moreover, infiltrating ductal carcinoma can be separated into at least 4 molecular subtypes designated luminal (ER+, PR+, and Her2/neu-), Her2 overexpressing (ER-, PR-, and Her2/neu+), basal-like (ER-, PR-, Her2/neu-, and CK5/6+, EGFR+), and normal breast-like (ER-, PR-, and Her2/neu-), each with different clinical outcomes. The importance of proliferative gene expression in these subtypes has been demonstrated and surrogate immunohistochemical markers include ER, PR, Her2/neu, and Ki67 for the more expensive molecular tests. Molecular technologies, importantly, have not only provided further insights into the heterogeneity of breast cancer but have also opened new avenues for treatment through the identification of signaling molecules important in the proliferation and survival of the neoplastic cells. The treatment of cancer thus shifts from the conventional approach of 'one size fits all' to one of personalized treatment tailored to the specific characteristics of the tumor. Pathologists continue to play their traditional role in diagnosis but, as purveyors of the excised tissue, pathologists now have the additional role of identifying biomarkers responsive to therapeutic manipulation, thus playing an inextricable role as diagnostic oncologists in the management of breast cancer.

Molecular assays in breast cancer pathology

Recent advances in understanding the molecular pathology of breast cancer offer significant potential to identify patients who may benefit from adjuvant therapies. To date, few of these advances are utilised in a routine setting. We review molecular assays that are currently in use or are in the advanced stages of development, which may be used as predictive or prognostic biomarkers in breast cancer.The only widely used breast cancer molecular assay is in situ hybridisation (ISH) for human epidermal growth factor receptor 2 (HER2) gene amplification and we highlight key issues with the interpretation of this assay, with particular attention to the difficulties of the equivocal category. New molecular assays such as ISH for the topoisomerase II alpha (TOP2A) gene and for the aberrations in the copy number of the centromeric region of chromosome 17 are readily performed in a standard histopathology laboratory, but to date there are insufficient data to support their routine use. We also review the current data on two commercially available multigene expression assays, Oncotype DX and MammaPrint and discuss their potential use. Overall, while new molecular assays have significant potential to improve patient selection for therapy, well-performed histopathology with reliable interpretation of standard hormone and HER2 assays provides the most important predictive and prognostic information in early breast cancer.

Markers of sensitivity, dependence and resistance to endocrine therapy for breast cancer

Owing to its efficacy and relative lack of toxicities, endocrine therapy is a major treatment modality for breast cancer. However, resistance and the inability to accurately predict response are obstacles to optimal management. There is a need to identify markers of clinical response and elucidate mechanisms of resistance. In this article, evidence will be presented demonstrating that: discovery of predictive markers is dependent upon the approach employed and the application required; and mechanisms of resistance are diverse and not simply mirror images of response. Different information may be obtained according to assessment read outs and type of analysis. Tumors respond to endocrine therapy in a variety of ways and a range of end points can be used to monitor hormone dependence, sensitivity and resistance to treatment. Different forms of endocrine therapies may have differing mechanisms of action - hence, markers of sensitivity/response can vary between treatments and there may be correspondingly differing mechanisms of resistance.

Estrogen receptor (ER) and progesterone receptor (PgR) in breast cancer of Indian women

OBJECTIVE

To determine the expressions and relationship between estrogen receptors (ERs) and progesterone receptors (PgRs) in breast cancer in Indian women.

PARTICIPANTS

Surgically removed breast cancer tissues were collected from Grant Medical College and Sir JJ Group of Hospitals, Mumbai, India, taking (n = 300) cases of infiltrating duct cancer of Indian women after radical mastectomy and lumpectomy; the age- and menopausal-related subgroups satisfied this requirement.

MEASUREMENTS

Statistical significance was calculated by the likelihood ratio test; relative risk served to check for significant differences. Relapse-free interval probabilities were calculated according to Kaplan and Meier, with Cox-Mantel test comparing survival functions and P values.

RESULTS

We observed that only in middle-aged postmenopausal patients bearing pT2 tumors were ER and PgR receptors shown to have a prognostic significance with the lowest tested cutoff value being 5 fmol/mg.

CONCLUSION

Immunohistochemistry analysis has been shown to be a prognostic factor for patients with breast cancer; the major aim of determining the ER receptor status is to assess predictive response to hormonal therapy.

Relationship between estrogen receptor, progesterone receptor, HER-2 and Ki67 expression and efficacy of aromatase inhibitors in advanced breast cancer

BACKGROUND

Surprisingly few data are published on the relevance of even commonly used biomarkers of response to aromatase inhibitors (AIs) in advanced breast cancer. Here, we aim to determine the effectiveness of AIs in that setting according to quantitative levels of estrogen receptor (ER), progesterone receptor (PgR) and Ki67 or human epithelial growth factor receptor-2 (HER-2) status.

PATIENTS AND METHODS

ER, PgR, HER-2 and Ki67 protein expressions were centrally assessed in 177 archival formalin-fixed paraffin-embedded primary or locally recurrent breast tumours from women who subsequently received AI treatment of advanced disease.

RESULTS

Among ER-positive patients (n = 146), higher PgR, but not ER, levels were associated with increased time to AI treatment failure (TTF). Higher Ki67 staining was associated with decreased TTF. ER-positive/HER-2-positive patients showed a non-significant trend for decreased TTF compared with ER-positive/HER-2-negative patients. PgR level, but not Ki67, remained a significant predictor of TTF in multivariate analysis of ER-positive patients.

CONCLUSIONS

Higher PgR and Ki67 levels are significantly associated with increased and decreased TTF, respectively, in ER-positive patients receiving AI treatment of advanced disease. The higher proliferation seen in PgR-negative tumours does not explain the poorer clinical responsiveness of this subgroup.

Long-term cultures of stem/progenitor cells from lobular and ductal breast carcinomas under non-adherent conditions

A small subpopulation of stem/progenitor cells can give rise to the diversity of differentiated cells that comprise the bulk of the tumor. Are proliferating cells, within the bulk of tumor, few cells with uncommon features? The cell biological approach provides a limitless model for studying the hierarchical organization of progenitor subpopulation and identifying potential therapeutic targets. Aim of the study was to expand patients' breast cancer cells for evaluating functional cell properties, and to characterize the protein expression profile of selected cells to be compared with that of primary tumors. Breast cancer cells from estrogen receptor (ERα) positive, HER2 negative lobular (LoBS cells) and ductal (DuBS cells) histotype were cultured under non-adherent conditions to form mammospheres. Sorting of the cells by their surface expression of CD24 and CD44 gave rise to subpopulations which were propagated, enriched and characterized for the expression of epithelial and stromal markers. We found that non-adherent culture conditions generate mammospheres of slowly proliferating cells; single cells, dissociated from mammospheres, grow in soft agar; long-term cultured LoBS and DuBS cells, CD44+/CD24low, express cytokeratin 5 (CK5), α-smooth muscle actin (α-sma) and vimentin, known as markers of basal/myoepithelial cells; and ERα (only DuBS cells), HER1 (EGF-Receptor), activated HER2, and cyclinD1 as markers of luminal epithelial cell. Isolates of cells from breast cancer patients may be a tool for a marker-driven testing of targeted therapies.

Using image analysis as a tool for assessment of prognostic and predictive biomarkers for breast cancer: How reliable is it?

BACKGROUND

Estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2) are important and well-established prognostic and predictive biomarkers for breast cancers and routinely tested on patient's tumor samples by immunohistochemical (IHC) study. The accuracy of these test results has substantial impact on patient management. A critical factor that contributes to the result is the interpretation (scoring) of IHC. This study investigates how computerized image analysis can play a role in a reliable scoring, and identifies potential pitfalls with common methods.

MATERIALS AND METHODS

Whole slide images of 33 invasive ductal carcinoma (IDC) (10 ER and 23 HER2) were scored by pathologist under the light microscope and confirmed by another pathologist. The HER2 results were additionally confirmed by fluorescence in situ hybridization (FISH). The scoring criteria were adherent to the guidelines recommended by the American Society of Clinical Oncology/College of American Pathologists. Whole slide stains were then scored by commercially available image analysis algorithms from Definiens (Munich, Germany) and Aperio Technologies (Vista, CA, USA). Each algorithm was modified specifically for each marker and tissue. The results were compared with the semi-quantitative manual scoring, which was considered the gold standard in this study.

RESULTS

For HER2 positive group, each algorithm scored 23/23 cases within the range established by the pathologist. For ER, both algorithms scored 10/10 cases within range. The performance of each algorithm varies somewhat from the percentage of staining as compared to the pathologist's reading.

CONCLUSIONS

Commercially available computerized image analysis can be useful in the evaluation of ER and HER2 IHC results. In order to achieve accurate results either manual pathologist region selection is necessary, or an automated region selection tool must be employed. Specificity can also be gained when strict quality assurance by a pathologist is invested. Quality assurance of image analysis by pathologists is always warranted. Automated image analysis should only be used as adjunct to pathologist's evaluation.

Aromatase inhibitors: prediction of response and nature of resistance

IMPORTANCE OF THE FIELD

Aromatase inhibitors (AIs) are recommended for and central to endocrine management of breast cancer patients. Response rates can be high, but resistance is a major obstacle. Optimal management therefore requires accurate prediction of response and an understanding of the nature by which resistance occurs. These are the subjects of this review.

AREAS COVERED IN THIS REVIEW

The complications of assessing response in different clinical settings and the types of response in terms of clinical, pathological, proliferative and molecular endpoints are reviewed. The current status of predictors of response such as estrogen receptors (ERs), progesterone receptors, other markers of estrogen action, ER phosphorylation, ER coregulators and multigene signatures are assessed. Different types of resistance to AIs, their heterogeneity, diversity in mechanisms of resistance and their identification are also considered.

WHAT THE READER WILL GAIN

The review provides fundamental information on response and predictors of response to AIs as well as an understanding of the diversity of resistance mechanisms to such endocrine agents.

TAKE HOME MESSAGES

ER status is the only factor used routinely for treatment selection, but additional markers are needed to predict response. Other markers have some predictive powers, but are of limited utility. The hope is, therefore, that discovery strategies based on genome-wide searches will identify new markers. Assessments may be required both before and after a short period of treatment so that early changes can be used to predict subsequent clinical response. Mechanisms of resistance to AIs are diverse. Knowledge of specific resistance mechanisms in individual cases will be necessary if strategies to circumvent resistance are to be developed rationally. A future can be envisaged in which molecular phenotyping of individual tumors is used to decide not only which patients should be treated with AIs but also whether AIs should be used alone or in combination/sequence with other drug regimes.

Targeting the receptor tyrosine kinase RET sensitizes breast cancer cells to tamoxifen treatment and reveals a role for RET in endocrine resistance

Endocrine therapy is the main therapeutic option for patients with estrogen receptor (ERalpha)-positive breast cancer. Resistance to this treatment is often associated with estrogen-independent activation of ERalpha. In this study, we show that in ERalpha-positive breast cancer cells, activation of the receptor tyrosine kinase RET (REarranged during Transfection) by its ligand GDNF results in increased ERalpha phosphorylation on Ser118 and Ser167 and estrogen-independent activation of ERalpha transcriptional activity. Further, we identify mTOR as a key component in this downstream signaling pathway. In tamoxifen response experiments, RET downregulation resulted in 6.2-fold increase in sensitivity of MCF7 cells to antiproliferative effects of tamoxifen, whereas GDNF stimulation had a protective effect against the drug. In tamoxifen-resistant (TAM(R)-1) MCF7 cells, targeting RET restored tamoxifen sensitivity. Finally, examination of two independent tissue microarrays of primary human breast cancers revealed that expression of RET protein was significantly associated with ERalpha-positive tumors and that in primary tumors from patients who subsequently developed invasive recurrence after adjuvant tamoxifen treatment, there was a twofold increase in the number of RET-positive tumors. Together these findings identify RET as a potentially important therapeutic target in ERalpha-positive breast cancers and in particular in tamoxifen-resistant tumors.

Use of molecular markers for predicting therapy response in cancer patients

Predictive markers are factors that are associated with upfront response or resistance to a particular therapy. Predictive markers are important in oncology as tumors of the same tissue of origin vary widely in their response to most available systemic therapies. Currently recommended oncological predictive markers include both estrogen and progesterone receptors for identifying patients with breast cancers likely to benefit from hormone therapy, HER-2 for the identification of breast cancer patients likely to benefit from trastuzumab, specific K-RAS mutations for the identification of patients with advanced colorectal cancer unlikely to benefit from either cetuximab or panitumumab and specific EGFR mutations for selecting patients with advanced non-small-cell lung cancer for treatment with tyrosine kinase inhibitors such as gefitinib and erlotinib. The availability of predictive markers should increase drug efficacy and decrease toxicity, thus leading to a more personalized approach to cancer treatment.

American Society of Clinical Oncology/College of American Pathologists guideline recommendations for immunohistochemical testing of estrogen and progesterone receptors in breast cancer (unabridged version)

PURPOSE

To develop a guideline to improve the accuracy of immunohistochemical (IHC) estrogen receptor (ER) and progesterone receptor (PgR) testing in breast cancer and the utility of these receptors as predictive markers.

METHODS

The American Society of Clinical Oncology and the College of American Pathologists convened an international Expert Panel that conducted a systematic review and evaluation of the literature in partnership with Cancer Care Ontario and developed recommendations for optimal IHC ER/PgR testing performance.

RESULTS

Up to 20% of current IHC determinations of ER and PgR testing worldwide may be inaccurate (false negative or false positive). Most of the issues with testing have occurred because of variation in pre-analytic variables, thresholds for positivity, and interpretation criteria.

RECOMMENDATIONS

The Panel recommends that ER and PgR status be determined on all invasive breast cancers and breast cancer recurrences. A testing algorithm that relies on accurate, reproducible assay performance is proposed. Elements to reliably reduce assay variation are specified. It is recommended that ER and PgR assays be considered positive if there are at least 1% positive tumor nuclei in the sample on testing in the presence of expected reactivity of internal (normal epithelial elements) and external controls. The absence of benefit from endocrine therapy for women with ER-negative invasive breast cancers has been confirmed in large overviews of randomized clinical trials.

Combined inhibitory effect of formestane and herceptin on a subpopulation of CD44+/CD24low breast cancer cells

In breast cancer, stromal cells surrounding cancer epithelial cells can influence phenotype by producing paracrine factors. Among many mediators of epithelial-stromal interactions, aromatase activity is perhaps one of the best studied. Clinical data suggest that estrogen-independent signaling leads to increased proliferation even during therapy with aromatase inhibitors (AIs). Molecular mechanism of crosstalk between the estrogen receptor (ER) and the epidermal growth factor receptor (HER) family have been implicated in resistance to endocrine therapy, but this interaction is unclear. The ability of aromatase to induce estradiol biosynthesis provides a molecular rationale to combine agents that target aromatase activity and the HER pathway. We targeted stromal-epithelial interactions using formestane, which exerts antiaromatase activity, combined with the monoclonal anti-HER2 antibody herceptin, in a subpopulation of CD44+/CD24low cells sorted from epithelial-mesenchymal co-cultures of breast cancer tissues. The growth inhibition was respectively 16% (P < 0.01) in the response to herceptin, 25% to formestane (P < 0.01), and 50% (P < 0.001) with the combination of the two drugs, suggesting that herceptin cooperates with formestane-induced inhibition of aromatase and this effect could be mediated through HER family receptors. In cells which expressed ERalpha, formestane/herceptin combination suppressed the mRNA expression of aromatase and HER2 and decreased cyclin D1 expression. These results show that combination therapies involving AIs and anti-HER2 can be efficacious for the treatment of cancer in experimental models and suggest that subtyping breast tumors gives useful information about response to treatment.

Protein expression profile and prevalence pattern of the molecular classes of breast cancer--a Saudi population based study

BACKGROUND

Breast cancer is not a single entity but a diverse group of entities. Advances in gene expression profiling and immunohistochemistry as its surrogate marker have led to the unmasking of new breast cancer molecular subtypes, resulting in the emergence of more elaborate classification systems that are therapeutically and prognostically more predictive. Molecular class distribution across various ethnic groups may also reveal variations that can lead to different clinical outcomes in different populations.

METHODS

We aimed to analyze the spectrum of molecular subtypes present in the Saudi population. ER, PR, HER2, EGFR and CK5/6 were used as surrogate markers for gene expression profiling to classify 231 breast cancer specimens. Correlation of each molecular class with Ki-67 proliferation index, p53 mutation status, histologic type and grade of the tumor was also carried out.

RESULTS

Out of 231 cases 9 (3.9%) were classified as luminal A (strong ER +ve, PR +ve or -ve), 37 (16%) as luminal B (weak to moderate ER +ve, and/or PR +ve), 40 (17.3%) as HER2+ (strong or moderately positive HER 2 with confirmation by silver enhanced in-situ hybridization) and 23 (10%) as basal (CK5/6 or EGFR +ve). Co-positivity of different markers in varied patterns was seen in 23 (10%) of cases which were grouped into a hybrid category comprising luminal B-HER2, HER2-basal and luminal-basal hybrids. Ninety nine (42.8%) of the tumors were negative for all five immunohistochemical markers and were labelled as unclassified (penta negative). A high Ki-67 proliferation index was seen in basal (p=0.007) followed by HER2+ class. Overexpression of p53 was predominantly seen in HER2+(p=0.001) followed by the basal group of tumors. A strong correlation was noted between invasive lobular carcinoma and hormone receptor expression with 8 out of 9 lobular carcinoma cases (88.9%) classifiable as luminal cancers. Otherwise, there was no association between the molecular class and the histologic type or grade of the tumor.

CONCLUSIONS

Subtyping by use of this immunohistochemical panel revealed a prevalence pattern that is unique to our population; luminal tumors comprised only 19.9%, and the unclassified group (penta negative) 42.8%, a distribution which is distinctive to our population and in contrast with all Western studies. The presence of a predominant unclassified group also suggests that the currently used molecular analytic spectrum may not completely encompass all molecular classes and there is a need to further refine and develop the existing classification systems.

Estimation of an evidence-based benchmark for the optimal endocrine therapy utilization rate in breast cancer

BACKGROUND

There are no evidence-based benchmarks to establish optimal rates of use of endocrine therapy in the whole breast cancer population. Reported utilization rates vary widely. The aim of the study was to estimate the optimal proportion of breast cancer patients who should receive endocrine therapy based on treatment guideline recommendations and to compare this with actual treatment rates.

METHODS

An optimal endocrine therapy utilization tree was constructed based on indications from evidence-based treatment guidelines. Frequency data on patient and tumour attributes were obtained from Australian cancer registries where possible and merged with the guideline recommendations to calculate the optimal utilization rate. These were compared with actual proportions obtained from published reports.

RESULTS

According to the best available evidence, the proportion of invasive breast cancer patients in whom endocrine therapy is indicated at diagnosis is 67%. Endocrine therapy is under-utilized in Australia (actual utilization rate 41%), and USA (35%), but approximate the benchmark rate in the UK (75%) and Italy (63%).

CONCLUSION

This evidence-based model provides a benchmark for optimal endocrine therapy utilization rates in the breast cancer population, and comparison of best practice evidence and actual treatment. The results show an underutilization of endocrine therapy in Australia and the USA, with more appropriate utilization in the UK and Italy.