Evaluation of neoadjuvant inhibition of aromatase activity and signal transduction in breast cancer

Synthesis and biological evaluation of novel 1,3,4-thiadiazole derivatives as possible anticancer agents

The synthesis of new N-(5-substituted-1,3,4-thiadiazol-2-yl)-2-[(5-(substituted amino)-1,3,4-thiadiazol-2-yl)thio]acetamide derivatives and investigation of their anticancer activities were the aims of this work. All the new compounds' structures were elucidated by elemental analyses, IR, 1H NMR, 13C NMR and MS spectral data. Anticancer activity studies of the compounds were evaluated against MCF-7 and A549 tumor cell lines. In addition, with the purpose of determining the selectivity of cytotoxic activities, the most active compound was screened against a noncancer NIH3T3 cell line (mouse embryonic fibroblast cells). Among the tested compounds, compound 4y (N-(5-ethyl-1,3,4-thiadiazol-2-yl)-2-((5-(p-tolylamino)-1,3,4-thiadiazol-2-yl)thio)acetamide), showed promising cytotoxic activity against MCF7 cancer cell with an IC 50value of 0.084 ± 0.020 mmol L-1 and against A549 cancer cell with IC 50 value of 0.034 ± 0.008 mmol L-1, compared with cisplatin. The aromatase inhibitory activity was evaluated for compound 4y on MCF-7 cell line showing promising activity with IC50 of 0.062 ± 0.004 mmol L-1.

Molecular modeling and synthesis of new 1,5-diphenylpyrazoles as breast cancer cell growth inhibitors

New pyrazoles have been synthesized and evaluated as breast cancer cell growth inhibitors. Condensation of the substituted pyrazole-4-carbaldehyde1with acetophenone and chloroacetophenone afforded α, β-unsaturated ketones2and3, respectively. Compounds2and3were subjected to different reactions using hydrazine hydrate, substituted hydrazine hydrate, hydroxylamine,o-phenylenediamine, malononitrile under different conditions affording 4-substituted pyrazole derivatives4–28. Structure elucidation of these compounds was conducted using IR,1H NMR,13C NMR, mass spectral data and elemental analysis. Antitumor activity of target compounds was tested against MCF-7 cell line (human breast cancer). Compounds4,10and20show significant antitumor activity against breast cancer. Docking was performed with protein 1UYK to study the binding mode of the designed compounds.

Neoadjuvant endocrine treatment in early breast cancer: An overlooked alternative?

During the last decade neoadjuvant endocrine therapy (NET) has moved from being reserved for elderly and frail non-chemotherapy candidates to a primary systemic modality in selected patients with hormone sensitive breast cancer. Neoadjuvant hormonal treatment in patients with hormone receptor positive, HER-2 negative early breast cancer is proven to be an effective and safe option; it is associated with a higher rate of breast conserving surgery (BCS), may reduce the need for adjuvant chemotherapy and enables a delay of surgery for medical or practical reasons. Clinical responses range from 13% to 100% with at least 3 months of NET. Methods of assessing response should include MRI of the breast, particularly in lobular tumours. In studies comparing tamoxifen with aromatase inhibitors (AI), AI proved to be superior in terms of tumour response and rates of BCS. Change in Ki67 is accepted as a validated endpoint for comparing endocrine neoadjuvant agents. Levels of Ki67 during treatment are more closely related to long-term prognosis than pretreatment Ki67. Neoadjuvant endocrine therapy provides a unique opportunity for studies of endocrine responsiveness and the development of new experimental drugs combined with systemic hormonal treatment.

Effect of targeted agents on the endocrine response of breast cancer in the neoadjuvant setting: a systematic review

Inhibition of aberrantly activated pathways cross-talking with hormone receptor (HR) improves response to endocrine therapy in patients with HR-positive advanced breast cancer. We performed a Pubmed database systematic review to ascertain the existence of a better clinical response when combining endocrine therapy with targeted agents in the neoadjuvant setting. Preclinical studies or trials evaluating toxicity were excluded.

We found nine phase II trials that fulfilled the research criteria. The endocrine agents used were third generation aromatase inhibitors (AIs), anastrozole, letrozole or exemestane. The investigated targeted agents were inhibitors of tyrosine kinase receptors such as gefitinib, imatinib or trastuzumab/lapatinib, inhibitors of mTOR, such as everolimus, inhibitors of COX-2, such as celecoxib, and inhibitors of angiogenesis, such as bevacizumab. The response rate (RR) observed combining endocrine and targeted agents ranged between 36% and 90%.

Overall the studies failed to show a remarkable advantage in RR in the combination group compared to historical control subjects receiving AIs alone.

Investigational platelet-derived growth factor receptor kinase inhibitors in breast cancer therapy

INTRODUCTION

Aberrant regulation of platelet-derived growth factors (PDGFs) and their receptors (PDGFR) has been shown to be involved in many solid tumors, including breast cancer. PDGFR-α and PDGFR-β expressions were documented in breast cancer and are correlated with tumor aggressiveness and metastasis. Preclinical evidence further suggests tumor stimulatory roles of PDGFRs expressed by tumor stroma cells and indicates a deleterious effect of stromal PDGFRs on intratumoral drug uptake.

AREAS COVERED

This review summarizes the present understanding of PDGF signaling in breast cancer based on experimental studies and available clinical trials. It also provides a critical discussion of selected ongoing clinical trials in patients with breast cancer involving PDGFR inhibition with tyrosine kinase inhibitors, specifically in endocrine responsive breast cancer.

EXPERT OPINION

An increased molecular understanding of response and resistance mechanisms to endocrine therapy will be essential for therapeutic advances in PDGFR-directed cancer therapy. Future developments in the field will rely on clinical studies where prospective analyses of target expression in breast cancer cells and in the tumor stroma are included. More selective PDGFR inhibitors with reduced side effects will be crucial for combinatorial therapies. Development of sensitive diagnostics is of critical importance for patient selection and monitoring of therapeutic effects.

The clinical trials of the Organisation for Oncology and Translational Research (OOTR)

The Organisation for Oncology and Translational Research (OOTR) was established in 2002 by Dr Louis WC Chow and Dr Masakazu Toi to gather medical professionals from different countries to work together in translational research as one of the missions of the organisation. Therefore, we seek to create networking among oncologists and develop effective interaction among the most advanced academic institutions throughout the world in order to conduct clinical trials and translational research together. Several clinical trials evaluating the use of neoadjuvant therapy for breast cancer have been designed and conducted for the past 10 years in the OOTR. The design of these studies has shifted from evaluating the efficacy and safety of new anticancer therapies and exploring new predictive and prognostic biomarkers to overcoming and unveiling the mechanism of tumor resistance as well as compiling predictive models for treatment response. This article briefly summarizes the concept and development of the OOTR clinical trial designs.

Enhanced expression of the PDGFR/Abl signaling pathway in aromatase inhibitor-resistant breast cancer

BACKGROUND

We have found that the platelet-derived growth factor receptor (PDGFR)/Abl signaling pathway is up-regulated as a determinant of the acquisition of resistance to estrogen deprivation in vitro. We aimed to determine its clinical relevance in aromatase inhibitor (AI)-resistant breast cancer.

PATIENTS AND METHODS

We identified a cohort of 45 patients with estrogen receptor-positive breast cancer who had been treated with an AI, subsequently relapsed and had biopsy material available from both the presentation and post-AI recurrent lesion. PDGFRα, PDGFRβ and Abl expression was assessed in formalin-fixed paraffin-embedded sections.

RESULTS

Tumor protein expression of PDGFRα (1.39-fold, P=0.0065), PDGFRβ (4.32-fold, P=0.006) and Abl (1.8-fold, P=0.001) was increased at the point of relapse. Tumor and stromal expression of PDGFRα as well as PDGFRβ was significantly correlated in pre-treatment and relapse samples. High post-treatment tumor and stromal PDGFRβ levels were associated with a short time to treatment failure (TTF). Expression of PDGFRα in relapsing tumor specimens was correlated with Abl expression and Ki67 levels. Furthermore, changes in Abl correlated significantly with changes in ER expression.

CONCLUSIONS

These clinical data support a role for enhanced PDGF/Abl signaling in AI-resistant disease and provide a rationale for targeting the pathway in endocrine-resistant breast cancer.

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.

RET in breast cancer: functional and therapeutic implications

Recent studies demonstrate that the receptor tyrosine kinase RET is overexpressed in a subset of ER-positive breast cancers and that crosstalk between RET and ER is important in responses to endocrine therapy. The development of small molecular inhibitors that target RET allows the opportunity to consider combination therapies as a strategy to improve response to treatment and to prevent and combat endocrine resistance. This review discusses: (i) the current knowledge about RET, its co-receptors and ligands in breast cancer; (ii) the breast cancer clinical trials involving agents that target RET; and (iii) the challenges that remain in terms of specificity of available inhibitors and in understanding the complex molecular mechanisms that underlie the resistance to endocrine therapy.

Gene expression profiles as an additional tool to conventional predictive factors to assist in management of early endocrine responsive breast cancer

Cancer treatment has revolutionized from a "one size fits all" approach to a more individualized approach with the advancement of medicine and molecular biology. Several predictive and prognostic factors have been studied and applied to clinical practice to assist clinicians in cancer management. In breast cancer therapeutics, the appearance of biomarkers such as expressions of hormone receptor and human epidermal growth factor (HER) receptors has modified treatment strategies from chemotherapy to molecular-targeted therapy including endocrine therapy and anti-HER therapy. With better understanding of the molecular level of tumorigenesis, cancer pathogenesis and metastases, several novel biomarkers such as cyclo-oxygennase-2 enzyme and tyrosine kinases have been discovered and new anti-cancer agents have been introduced into the currently available treatments. The change has also modified pre-operative treatment for locally advanced and early breast cancers. The neo-adjuvant treatment indeed provides an excellent platform for translational research which is a widely used research method in clinical research. The study of gene and protein expressions from tissue and blood samples collected before, during and after neo-adjuvant treatment provides a lot of keys to decipher the signaling pathways and discover novel biomarkers which are essential for development of new drugs and prediction of the clinical outcome of therapy. The addition of gene expression profiling to conventional predictive factors will give more prognostic information to clinicians for better management of the disease.

Aromatase inhibitors in breast cancer

Estrogens play important roles in breast cancer development and progression. In postmenopausal women, traditional endocrine therapies such as tamoxifen have sought to inhibit estrogen action by targeting the estrogen receptor itself. However, newer treatments are evolving that target estrogen production in postmenopausal tissues through inhibition of the aromatase enzyme. Clinical data demonstrate that these aromatase inhibitors are superior to tamoxifen as adjuvant therapy for breast cancer and have now replaced tamoxifen as first line therapy in a number of treatment regimens for postmenopausal breast cancer patients.

Quantitative immunohistochemical expression of c Kit in breast carcinomas is predictive of patients' outcome

Background:

c Kit (CD117) expression in tissues has been reported as a relevant target for specific therapy in some human malignancies, but has been poorly documented in breast carcinomas

Methods:

The prognostic significance of c Kit in a series of 924 breast carcinomas (mean follow-up, 79 months) was investigated using standardised high-throughput quantitative densitometry of immunohistochemical precipitates in tissue microarrays.

Results:

c Kit was expressed in 14.7% breast carcinomas (and in 42 out of 586 node-negative tumours). In univariate analysis, (log-rank test) the score of c Kit expression correlated with poor patient outcome P=0.02 and particularly in node-negative cases (P=0.002). In multivariate Cox analysis, c Kit was an indicator of metastasis independent of 25 other concomitantly evaluated markers of prognosis. Logistic regression showed that c Kit ranked 10 out of 25 (P=0.041), and was included in a 10-marker signature that allowed 79.2% of the patients to be correctly classified in the metastatic or metastasis-free categories independently of hormone receptors and HER-2 status. Interestingly, c Kit was also a significant predictor of metastasis in node-negative tumours (2 out of 25 ranking, P<0.0001) and included in a six-marker signature of prognosis, correctly classifying 88.6% of the patients (P<0.0001).

Conclusion:

We concluded that, as assessed by quantitative immunohistochemistry, c Kit is an independent prognostic indicator that could also potentially serve as a target for specific therapy in breast carcinomas.

Triple-negative breast cancer

PURPOSE OF REVIEW

Triple-negative breast cancer has been of great interest to oncologists because these cancers do not benefit from hormonal therapies or treatments targeted against human epidermal growth factor receptor 2 receptors. The only systemic therapy currently available is chemotherapy, and prognosis remains poor. We would like to describe recent pathological and genetic advancements and their possible implications on the development of new treatment strategies.

RECENT FINDINGS

Increasing pathological and molecular knowledge has led to a better understanding of breast cancer in general. Triple-negative breast cancer, however, remains a heterogeneous subgroup with difficult-to-define subtypes. New targeted therapies are currently being developed and researched.

SUMMARY

The recent advances in pathological and molecular knowledge have changed the landscape of breast cancer, with triple-negative breast cancer emerging as a pathological and clinical heterogeneous group. The main challenge lies in the development of new tailored treatment strategies for the various subgroups, with receptor kinase inhibition as the most promising new evolution to date. Further trials are needed to validate these new treatment options.