Ruth O'Regan

Bioconjugated quantum dots for multiplexed and quantitative immunohistochemistry

Bioconjugated quantum dots (QDs) provide a new class of biological labels for evaluating biomolecular signatures (biomarkers) on intact cells and tissue specimens. In particular, the use of multicolor QD probes in immunohistochemistry is considered one of the most important and clinically relevant applications. At present, however, clinical applications of QD-based immunohistochemistry have achieved only limited success. A major bottleneck is the lack of robust protocols to define the key parameters and steps. Here, we describe our recent experience, preliminary results and detailed protocols for QD–antibody conjugation, tissue specimen preparation, multicolor QD staining, image processing and biomarker quantification. The results demonstrate that bioconjugated QDs can be used for multiplexed profiling of molecular biomarkers, and ultimately for correlation with disease progression and response to therapy. In general, QD bioconjugation is completed within 1 day, and multiplexed molecular profiling takes 1–3 days depending on the number of biomarkers and QD probes used.

Emerging use of nanoparticles in diagnosis and treatment of breast cancer

The biological application of nanoparticles is a rapidly developing area of nanotechnology that raises new possibilities in the diagnosis and treatment of human cancers. In cancer diagnostics, fluorescent nanoparticles can be used for multiplex simultaneous profiling of tumour biomarkers and for detection of multiple genes and matrix RNA with fluorescent in-situ hybridisation. In breast cancer, three crucial biomarkers can be detected and accurately quantified in single tumour sections by use of nanoparticles conjugated to antibodies. In the near future, the use of conjugated nanoparticles will allow at least ten cancer-related proteins to be detected on tiny tumour sections, providing a new method of analysing the proteome of an individual tumour. Supermagnetic nanoparticles have exciting possibilities as contrast agents for cancer detection in vivo, and for monitoring the response to treatment. Several chemotherapy agents are available as nanoparticle formulations, and have at least equivalent efficacy and fewer toxic effects compared with conventional formulations. Ultimately, the use of nanoparticles will allow simultaneous tumour targeting and drug delivery in a unique manner. In this review, we give an overview of the use of clinically applicable nanoparticles in oncology, with particular focus on the diagnosis and treatment of breast cancer.

Proton-Sponge Coated Quantum Dots for siRNA Delivery and Intracellular Imaging

We report the rational design of multifunctional nanoparticles for short-interfering RNA (siRNA) delivery and imaging based on the use of semiconductor quantum dots (QDs) and proton-absorbing polymeric coatings (proton sponges). With a balanced composition of tertiary amine and carboxylic acid groups, these nanoparticles are specifically designed to address longstanding barriers in siRNA delivery such as cellular penetration, endosomal release, carrier unpacking, and intracellular transport. The results demonstrate dramatic improvement in gene silencing efficiency by 10-20-fold and simultaneous reduction in cellular toxicity by 5-6-fold, when compared directly with existing transfection agents for MDA-MB-231 cells. The QD-siRNA nanoparticles are also dual-modality optical and electron-microscopy probes, allowing real-time tracking and ultrastructural localization of QDs during delivery and transfection. These new insights and capabilities represent a major step toward nanoparticle engineering for imaging and therapeutic applications.

Everolimus for women with trastuzumab-resistant, HER2-positive, advanced breast cancer (BOLERO-3): a randomised, double-blind, placebo-controlled phase 3 trial

BACKGROUND Disease progression in patients with HER2-positive breast cancer receiving trastuzumab might be associated with activation of the PI3K/Akt/mTOR intracellular signalling pathway. We aimed to assess whether the addition of the mTOR inhibitor everolimus to trastuzumab might restore sensitivity to trastuzumab. METHODS In this randomised, double-blind, placebo-controlled, phase 3 trial, we recruited women with HER2-positive, trastuzumab-resistant, advanced breast carcinoma who had previously received taxane therapy. Eligible patients were randomly assigned (1:1) using a central patient screening and randomisation system to daily everolimus (5 mg/day) plus weekly trastuzumab (2 mg/kg) and vinorelbine (25 mg/m(2)) or to placebo plus trastuzumab plus vinorelbine, in 3-week cycles, stratified by previous lapatinib use. The primary endpoint was progression-free survival (PFS) by local assessment in the intention-to-treat population. We report the final analysis for PFS; overall survival follow-up is still in progress. This trial is registered with ClinicalTrials.gov, number NCT01007942. FINDINGS Between Oct 26, 2009, and May 23, 2012, 569 patients were randomly assigned to everolimus (n=284) or placebo (n=285). Median follow-up at the time of analysis was 20.2 months (IQR 15.0-27.1). Median PFS was 7.00 months (95% CI 6.74-8.18) with everolimus and 5.78 months (5.49-6.90) with placebo (hazard ratio 0.78 [95% CI 0.65-0.95]; p=0.0067). The most common grade 3-4 adverse events were neutropenia (204 [73%] of 280 patients in the everolimus group vs 175 [62%] of 282 patients in the placebo group), leucopenia (106 [38%] vs 82 [29%]), anaemia (53 [19%] vs 17 [6%]), febrile neutropenia (44 [16%] vs ten [4%]), stomatitis (37 [13%] vs four [1%]), and fatigue (34 [12%] vs 11 [4%]). Serious adverse events were reported in 117 (42%) patients in the everolimus group and 55 (20%) in the placebo group; two on-treatment deaths due to adverse events occurred in each group. INTERPRETATION The addition of everolimus to trastuzumab plus vinorelbine significantly prolongs PFS in patients with trastuzumab-resistant and taxane-pretreated, HER2-positive, advanced breast cancer. The clinical benefit should be considered in the context of the adverse event profile in this population.

Insulin-like Growth Factor-I–Dependent Up-regulation of ZEB1 Drives Epithelial-to-Mesenchymal Transition in Human Prostate Cancer Cells

The epithelial-to-mesenchymal transition (EMT) is crucial for the migration and invasion of many epithelial tumors, including prostate cancer. Although it is known that ZEB1 overexpression promotes EMT primarily through down-regulation of E-cadherin in a variety of cancers, the soluble ligands responsible for the activation of ZEB1 have yet to be identified. In the present study, we investigated the role of insulin-like growth factor-I (IGF-I) in the regulation of ZEB1 during EMT associated with prostate tumor cell migration. We found that ZEB1 is expressed in highly aggressive prostate cancer cells and that its expression correlates directly with Gleason grade in human prostate tumors (P < 0.001). IGF-I up-regulates ZEB1 expression in prostate cancer cells exhibiting an epithelial phenotype. In prostate cancer cells displaying a mesenchymal phenotype, ZEB1 inhibition reverses the suppression of E-cadherin protein and down-regulates the expression of the mesenchymal markers N-cadherin and fibronectin. Furthermore, ZEB1 blockade decreases migratory and invasive potential in ARCaP(M) compared with the control. These results identify ZEB1 as a key transcriptional regulator of EMT in prostate cancer and suggest that the aberrant expression of ZEB1 in prostate cancer cells occurs in part in response to IGF-I stimulation.

Phase I Study of Everolimus Plus Weekly Paclitaxel and Trastuzumab in Patients With Metastatic Breast Cancer Pretreated With Trastuzumab

PURPOSE To determine the recommended dose of everolimus, a mammalian target of rapamycin inhibitor, combined with paclitaxel and trastuzumab in patients with human epidermal growth factor receptor 2 (HER2)-overexpressing metastatic breast cancer pretreated with trastuzumab. METHODS In this phase Ib, multicenter, dose-escalation study, patients were treated with everolimus 5 mg/d, 10 mg/d, or 30 mg/wk in combination with paclitaxel (80 mg/m(2) days 1, 8, and 15 every 4 weeks) and trastuzumab (2 mg/kg weekly). End points included end-of-cycle 1 dose-limiting toxicity (DLT) rate (primary end point), safety, relative dose intensity of study drugs, overall response rate (ORR), and pharmacokinetics. RESULTS Of 33 patients enrolled, 31 were pretreated with taxanes, and 32 were resistant to trastuzumab. Patients received a median of two lines of chemotherapy in the metastatic setting (range, 0 to 17 lines). Three patients experienced cycle 1 DLTs: febrile neutropenia (5 mg/d), stomatitis (10 mg/d), and confusion (30 mg/wk). Grade 3 to 4 neutropenia was the most common toxicity observed (n = 17 patients [52%]). On the basis of observed DLTs and overall safety, 10 mg/d was recommended for additional development. Twenty-seven patients had measurable disease and were evaluable for efficacy. Among these patients, ORR was 44%. Overall disease was controlled for 6 months or more in 74%. Median progression-free survival was 34 weeks (95% CI, 29.1 to 40.7 weeks). Among 11 patients who were resistant to both trastuzumab and taxane, a similar level of antitumor activity was observed (ORR, 55%). CONCLUSION Everolimus combined with weekly paclitaxel and trastuzumab was generally well tolerated and had encouraging antitumor activity in patients with trastuzumab-pretreated and -resistant metastatic HER2-overexpressing breast cancer.

Bidirectional Crosstalk between Leptin and Insulin-like Growth Factor-I Signaling Promotes Invasion and Migration of Breast Cancer Cells via Transactivation of Epidermal Growth Factor Receptor

Obesity is an independent risk factor for breast cancer, and obese breast cancer patients exhibit a higher risk for larger tumor burden and increased metastasis. Obesity, as associated with metabolic syndrome, results in an increase in circulating insulin-like growth factor (IGF), which acts as a mitogen. In addition, higher plasma level of adipocytokine leptin is associated with obesity. In the present study, we show that cotreatment with leptin and IGF-I significantly increases proliferation as well as invasion and migration of breast cancer cells. We found a novel bidirectional crosstalk between leptin and IGF-I signaling; IGF-I induced phosphorylation of leptin receptor (Ob-Rb) and leptin induced phosphorylation of IGF-I receptor (IGF-IR), whereas cotreatment induced synergistic phosphorylation and association of Ob-Rb and IGF-IR along with activation of downstream effectors, Akt and extracellular signal-regulated kinase. Leptin increased phosphorylation of IGF signaling molecules insulin-receptor substrate (IRS)-1 and IRS-2. Interestingly, we found that leptin and IGF-I cotreatment synergistically transactivated epidermal growth factor receptor (EGFR), depending on the proteolytic release of EGFR ligands, as the broad-spectrum matrix metalloproteinase inhibitor GM6001 could inhibit this effect. Using clinically relevant EGFR inhibitors, erlotinib and lapatinib, we found that inhibition of EGFR activation effectively inhibited leptin- and IGF-I-induced invasion and migration of breast cancer cells. Taken together, these data suggest a novel bidirectional crosstalk between leptin and IGF-I signaling that transactivates EGFR and promotes the metastatic properties as well as invasion and migration of breast cancer cells. Our findings indicate the possibility of using EGFR inhibitors erlotinib and lapatinib to counter the procancerous effects of leptin and IGF-I in breast cancers.

The PI3K/AKT/mTOR pathway in breast cancer: targets, trials and biomarkers

The phosphoinositide 3 kinase (PI3K)/Akt/mammalian (or mechanistic) target of rapamycin (mTOR) pathway is a complicated intracellular pathway, which leads to cell growth and tumor proliferation and plays a significant role in endocrine resistance in breast cancer. Multiple compounds targeting this pathway are being evaluated in clinical trials. These agents are generally well tolerated and can be used in combination with targeted therapies, endocrine therapy or cytotoxic agents. The identification of subtypes of tumors more likely to respond to these therapeutics cannot be overemphasized, since breast cancer is a very heterogeneous malignancy. Activation of pathways such as KRAS and MEK can act as escape mechanisms that lead to resistance, thus a combination of agents targeting multiple steps of the intracellular machinery is promising. There is evidence that tumors with PIK3CA mutations are more sensitive to inhibitors of the PI3K pathway but this has yet to be validated. Large clinical trials with correlative studies are necessary to identify reliable biomarkers of efficacy.

Age/race differences in HER2 testing and in incidence rates for breast cancer triple subtypes: a population-based study and first report.

Although US year 2000 guidelines recommended characterizing breast cancers by human epidermal growth factor receptor 2 (HER2), national cancer registries do not collect HER2, rendering a population‐based understanding of HER2 and clinical “triple subtypes” (estrogen receptor [ER] / progesterone receptor [PR] / HER2) largely unknown. We document the population‐based prevalence of HER2 testing / status, triple subtypes and present the first report of subtype incidence rates.

Triple-negative breast cancer in African-American women: disparities versus biology

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype that disproportionately affects BRCA1 mutation carriers and young women of African origin. There is evidence that African-American women with TNBC have worse clinical outcomes than women of European descent. However, it is unclear whether survival differences persist after adjusting for disparities in access to health-care treatment, co-morbid disease and income. It remains controversial whether TNBC in African-American women is a molecularly distinct disease or whether African-American women have a higher incidence of aggressive biology driven by disparities: there is evidence in support of both. Understanding the relative contributions of biology and disparities is essential for improving the poor survival rate of African-American women with TNBC.