Novel targeted agents for the treatment of advanced breast cancer

The discovery of the molecular processes involved in cancer development has led to the design of an array of targeted agents. These agents, directed to specific proteins in the machinery of cancer cells, interfere with vital cascades involved in cell invasion, metastasis, apoptosis, cell-cycle control and angiogenesis. In breast cancer, the main pathways studied and targeted by drugs are the HER2 pathway, EGFR, VEGF, PI3K/Akt/mammalian target of rapamycin (PI3K-M-Tor), IGF/IGFR, poly(ADP ribose) polymerase 1, HDAC and many others. In this review, we present the most promising studies of these new targeted therapies and novel combination of targeted therapies with cytotoxic agents for the treatment of breast cancer patients.

Soluble KIT correlates with clinical outcome in patients with metastatic breast cancer treated with sunitinib

Background

Sunitinib inhibits vascular endothelial growth factor receptors (VEGFRs), platelet-derived growth factor receptors, and stem cell factor receptor (KIT). The ability of soluble (s)KIT, VEGF-A, sVEGFR-2, and sVEGFR-3 to predict clinical outcome was analyzed in 61 patients with previously treated metastatic breast cancer (MBC) in a phase II study of sunitinib monotherapy (ClinicalTrials.gov NCT00078000).

Methods

Plasma concentrations of soluble proteins were measured at baseline and during treatment with sunitinib 50 mg/day (4 weeks on treatment, 2 weeks off treatment). Baseline concentrations and maximal percent change during the first two treatment cycles were stratified by median values and evaluated for correlation with median time to tumor progression (TTP) and overall survival (OS). This latter fixed time period was chosen to avoid bias accruing from patients who were on study for longer periods of time.

Results

TTP was significantly longer in patients having median or higher maximal percent sKIT change compared with patients with less than the median change (21.7 vs. 7.9 weeks; p < 0.0001). Similarly, OS was significantly longer in patients having median or higher sKIT change versus less than the median change (53.7 vs. 25.7 weeks; p = 0.018). Significant prolongation of OS (62.6 vs. 32.3 weeks; p = 0.032), but not TTP, was observed in patients with a median or higher maximal percent VEGF-A change compared with less than the median change. Maximal percent change of sVEGFR-2 or sVEGFR-3 concentrations and baseline concentrations of all four proteins were not predictive of clinical outcome.

Conclusions

This exploratory analysis suggests that changes in sKIT and possibly VEGF-A early during sunitinib treatment may be predictive of clinical outcome in MBC.

Complete longitudinal analyses of the randomized, placebo-controlled, phase III trial of sunitinib in patients with gastrointestinal stromal tumor following imatinib failure

PURPOSE

To analyze final long-term survival and clinical outcomes from the randomized phase III study of sunitinib in gastrointestinal stromal tumor patients after imatinib failure; to assess correlative angiogenesis biomarkers with patient outcomes.

EXPERIMENTAL DESIGN

Blinded sunitinib or placebo was given daily on a 4-week-on/2-week-off treatment schedule. Placebo-assigned patients could cross over to sunitinib at disease progression/study unblinding. Overall survival (OS) was analyzed using conventional statistical methods and the rank-preserving structural failure time (RPSFT) method to explore cross-over impact. Circulating levels of angiogenesis biomarkers were analyzed.

RESULTS

In total, 243 patients were randomized to receive sunitinib and 118 to placebo, 103 of whom crossed over to open-label sunitinib. Conventional statistical analysis showed that OS converged in the sunitinib and placebo arms (median 72.7 vs. 64.9 weeks; HR, 0.876; P = 0.306) as expected, given the cross-over design. RPSFT analysis estimated median OS for placebo of 39.0 weeks (HR, 0.505, 95% CI, 0.262-1.134; P = 0.306). No new safety concerns emerged with extended sunitinib treatment. No consistent associations were found between the pharmacodynamics of angiogenesis-related plasma proteins during sunitinib treatment and clinical outcome.

CONCLUSIONS

The cross-over design provided evidence of sunitinib clinical benefit based on prolonged time to tumor progression during the double-blind phase of this trial. As expected, following cross-over, there was no statistical difference in OS. RPSFT analysis modeled the absence of cross-over, estimating a substantial sunitinib OS benefit relative to placebo. Long-term sunitinib treatment was tolerated without new adverse events.

A phase II trial of Sunitinib malate in recurrent and refractory ovarian, fallopian tube and peritoneal carcinoma

OBJECTIVE

Ovarian cancer is a highly angiogenic tumor and a model for antiangiogenic research. The tyrosine kinase receptor inhibitors target several receptors allowing for the pharmacological disruption of several independent pathways. Sunitinib malate is a multitargeted tyrosine kinase inhibitor. A phase II study utilizing a modified dosing schedule was conducted to assess the efficacy and safety of Sunitinib in recurrent ovarian, fallopian tube and peritoneal carcinoma.

METHODS

A nonrandomized phase II study was modeled as a two-stage Simon design initially enrolling 17 evaluable participants in stage one and 18 patients in stage two. Patients received the study drug at 37.5mg every day over a 28 day treatment cycle until clinical or radiological evidence of progressive disease. Disease was evaluated radiographically and best overall response was defined using the RECIST 1.0 criteria. The primary objective of this study was to define the response rate (defined as complete response and partial response) while the secondary objectives included both the progression free rate as well as the safety of this agent in this patient population.

RESULTS

The response rate (PR+CR) was 8.3% (95% confidence interval: 1.8%, 22.5%). The 16-week and 24 week progression-free survival estimate was 36% (95% confidence interval and 19.2%), respectively. The median progression-free survival estimate was 9.9 weeks. Hypertension and gastrointestional events were the most common toxicities noted.

CONCLUSIONS

A modest response rate of 8.3% was achieved with Sunitinib malate. This phase II study adds to the body of literature of VEGFR inhibitors and further underscores the need of defining a genetic angiogenic signature.

Contrasting effects of sunitinib within in vivo models of metastasis

Sunitinib is a potent and clinically approved tyrosine kinase inhibitor that can suppress tumour growth by inhibiting angiogenesis. However, conflicting data exist regarding the effects of this drug on the growth of metastases in preclinical models. Here we use 4T1 and RENCA tumour cells, which both form lung metastases in Balb/c mice, to re-address the effects of sunitinib on the progression of metastatic disease in mice. We show that treatment of mice with sunitinib prior to intravenous injection of tumour cells can promote the seeding and growth of 4T1 lung metastases, but not RENCA lung metastases, showing that this effect is cell line dependent. However, increased metastasis occurred only upon administration of a very high sunitinib dose, but not when lower, clinically relevant doses were used. Mechanistically, high dose sunitinib led to a pericyte depletion effect in the lung vasculature that correlated with increased seeding of metastasis. By administering sunitinib to mice after intravenous injection of tumour cells, we demonstrate that while sunitinib does not inhibit the growth of 4T1 lung tumour nodules, it does block the growth of RENCA lung tumour nodules. This contrasting response was correlated with increased myeloid cell recruitment and persistent vascularisation in 4T1 tumours, whereas RENCA tumours recruited less myeloid cells and were more profoundly devascularised upon sunitinib treatment. Finally, we show that progression of 4T1 tumours in sunitinib treated mice results in increased hypoxia and increased glucose metabolism in these tumours and that this is associated with a poor outcome. Taken together, these data suggest that the effects of sunitinib on tumour progression are dose-dependent and tumour model-dependent. These findings have relevance for understanding how anti-angiogenic agents may influence disease progression when used in the adjuvant or metastatic setting in cancer patients.

Targeting angiogenesis in metastatic breast cancer

Angiogenesis has become an important target in the treatment of several solid tumors, including breast cancer. As monotherapy, antiangiogenic agents have demonstrated limited activity in metastatic breast cancer (MBC); therefore, they have generally been developed for use in combination with chemotherapies. Thus far, the experience with antiangiogenic agents for MBC has been mixed. The results from one study assessing addition of the monoclonal antibody bevacizumab to paclitaxel led to approval of bevacizumab for MBC. However, the modest improvement of progression-free survival rates in subsequent MBC studies has led to reappraisal of bevacizumab. Phase III studies have not produced evidence supporting use of the multikinase inhibitor sunitinib alone or in combination with MBC chemotherapy. Experience with sorafenib in a phase IIb program indicates potential when used in select combinations, particularly with capecitabine; however, phase III confirmatory data are needed. Although antiangiogenic therapies combined with chemotherapy have increased progression-free survival rates for patients with MBC, increases in overall survival times have not been observed. Some studies have tried to combine antiangiogenic agents such as bevacizumab and sunitinib or sorafenib, but that approach has been limited because of toxicity concerns. Sequential use of antiangiogenic agents with differing mechanisms of action may be an effective approach. Despite setbacks, angiogenesis will likely remain an important target of treatment for selected patients with MBC.

Pharmacological strategies to overcome HER2 cross-talk and Trastuzumab resistance

Approximately 20-30% of breast cancers show increased expression of the HER2 receptor tyrosine kinase. Trastuzumab (Herceptin) is a clinically approved anti-HER2 monoclonal antibody. Many patients with HER2-overexpressing metastatic breast cancer respond to trastuzumab; however, a subset display primary drug resistance. In addition, many patients who initially respond to trastuzumab ultimately develop disease progression. Multiple molecular mechanisms contributing to trastuzumab resistance have been proposed in the literature. These mechanisms include cross-signaling from related HER/erbB receptors and compensatory signaling from receptors outside of the HER/erbB family, including receptors for insulin-like growth factor-I, vascular endothelial growth factor, and transforming growth factor beta. The major downstream signaling pathway activated by HER2 cross-talk is PI3K/mTOR, and a potential integrator of receptor cross-talk is Src-focal adhesion kinase (FAK) signaling. PI3K, Src, and FAK have independently been implicated in trastuzumab resistance. In this review, we will discuss pharmacological inhibition of HER2 cross-talk as a strategy to treat trastuzumab-refractory HER2-overexpresssing breast cancer.

Antiangiogenic therapy in the management of breast cancer

An improved understanding of the important role of angiogenesis in tumor biology has led to development of different antiangiogenic therapies. Numerous clinical studies for several antiangiogenic agents have recently been conducted in breast cancer patients and have shown clinically significant improvement in outcomes. This review focuses on current progress in the field of antiangiogenic therapy in the management of breast cancer, also highlighting issues regarding future therapeutic development that result in the greatest clinical benefits and minimizing the adverse effects.

Determination of soluble vascular endothelial growth factor receptor 3 (sVEGFR-3) in plasma as pharmacodynamic biomarker

Soluble VEGFR-3 (sVEGFR-3) is a potential biomarker for the anti-angiogenic activity of tyrosine kinase inhibitors. The aim of this investigation was the validation of an enzyme-linked immunosorbent assay (ELISA) to measure sVEGFR-3 in human plasma and the investigation of its applicability in clinical trials as first step of the biomarker validation process. General validation criteria were assessed based on current guidelines and recommendations for immunoassays. The ELISA was applied in two clinical trials including healthy volunteers and metastatic colorectal cancer (mCRC) patients receiving 50 or 37.5mg sunitinib per day, respectively. SVEGFR-3 was measured at predefined time points. Undiluted, inactivated fetal calf serum was identified as surrogate matrix to substitute for human plasma. Dilutional linearity and parallelism could be successfully confirmed. The analyte was measured in the study matrix with intra- and inter-run precision and accuracy ≤20%. Stability was proven over a period of at least 15 months as well as upon three freeze-thaw cycles. SVEGFR-3 concentrations decreased in response to sunitinib to 57% (IQR 50-88%) and 58% (IQR 47-80%) of the respective baseline concentrations in healthy volunteers and mCRC patients, respectively, with subsequent increase after stop of treatment. The ELISA for the quantification of sVEGFR-3 in human plasma was successfully validated. The applicability of the assay was demonstrated in two clinical trials.

Triple-negative breast cancer: are we making headway at least?

The so-called triple-negative breast cancer, as defined by tumors that lack estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2 (HER2) overexpression, has generated growing interest in recent years despite representing less than 20% of all breast cancers. These tumors constitute an important clinical challenge, as they do not respond to endocrine treatment and other targeted therapies. As a group they harbor an aggressive clinical phenotype with early development of visceral metastases and a poor long-term prognosis. While chemotherapy remains effective in triple-negative disease, research continues to further identify potential new targets based on phenotypical and molecular characteristics of these tumors. In this respect, the presence of a higher expression of different biomarkers including epidermal growth factor receptor, vascular endothelial growth factor receptor, fibroblast growth factor receptor and Akt activation has led to a proliferation of clinical trials assessing the role of inhibitors to these pathways in triple-negative tumors. Moreover, the described overlap between triple-negative and basal-like tumors, and the similarities with tumors arising in the BRCA1 mutation carriers has offered potential therapeutic avenues for patients with these cancers including poly (ADP-ribose) polymerase inhibitors and a focus on a higher sensitivity to alkylating chemotherapy agents. Results from these trials have shown some benefit in small subgroups of patients, even in single-agent therapy, which reflects the heterogeneity of triple-negative breast cancer and highlights the need for a further subclassification of these types of tumors for better prognosis identification and treatment individualization.

[Cardiotoxicity of chemotherapies]

The spectrum of chemotherapy's cardiac side effect of chemotherapy has expanded with the new combinations of cytotoxic and targeted therapies over the past 10 years. Moreover, cancer therapy administrated to "new" populations, especially elderly patients or patients with cardiovascular disease and/or coronary artery disease history, has increased considerably. According to the American College of Cardiology and American Heart Association (ACC/AHA), patients receiving chemotherapy can be considered in the A group of heart failure. Many cardiovascular adverse effects appear with cancer therapy and suspend treatment purchase, or leading to an alteration of quality of life, and increasing mortality risks. The most clinically evident cardiotoxicity and best known is the anthracyclines adverse effect. Other cytotoxic are associated with a significant risk of cardiovascular complications include alkylating agents such as 5-fluorouracil and paclitaxel. Cardiovascular adverse effects are associated with the use of targeted therapies such as tyrosine kinase inhibitors: trastuzumab, bevacizumab. At the same time, drugs used to hematological malignancies, as acid all-trans-retinoic acid and arsenic trioxide are cardiotoxics. The most serious cardiac complications of cancer therapies is heart congestive failure, mainly due to the use of anthracyclines, cyclophosphamide and trastuzumab, usually at high doses. Myocardial ischemia is mainly caused by interferon and antimetabolites. Other side effects may occur such as hypotension, hypertension, arrhythmias and conduction disturbances, pericarditis, and thromboembolic complications.

Targeted therapies in breast cancer: are heart and vessels also being targeted?

The concept of 'targeted' therapies implies that such drugs only act on cells that specifically express the particular target, therefore giving rise to a low incidence of side effects. However, targeted therapies currently approved for the treatment of breast cancer have demonstrated a relatively high incidence of cardiovascular events. The anti-HER2 agents trastuzumab and lapatinib may cause left ventricular dysfunction or even congestive heart failure. Bevacizumab, an antiangiogenic drug, has been shown to increase the risk of hypertension, cardiovascular dysfunction and thromboembolic events. In addition, several anti-human epidermal growth factor receptor 2 (HER2) and antiangiogenic agents plus their combinations are currently being developed and evaluated for the treatment of breast cancer. In this review, we aim to assess the incidence of cardiac adverse events associated with targeted therapies designed to block HER2 and angiogenic pathways.

The BOLERO-2 trial: the addition of everolimus to exemestane in the treatment of postmenopausal hormone receptor-positive advanced breast cancer

The combination of the mTOR inhibitor everolimus with the aromatase inhibitor exemestane was evaluated in the randomized Phase III BOLERO-2 trial. Research has indicated that aberrant signaling through the mTOR pathway is associated with resistance to endocrine therapies. The BOLERO-2 trial examined the effects on progression-free survival of the addition of everolimus to exemestane in a patient population of postmenopausal, hormone receptor-positive, advanced breast cancer. At the interim analysis, the median progression-free survival assessed by local investigators was 6.9 months for everolimus plus exemestane versus 2.8 months for placebo plus exemestane (hazard ratio: 0.43; p < 0.001), and by central assessment was 10.6 versus 4.1 months, respectively (hazard ratio: 0.36; p < 0.001). The everolimus plus exemestane arm showed greater number of grade 3 and 4 adverse events. This study suggests that the addition of everolimus to exemestane is a potential viable treatment option for this patient population.

A multicenter phase II study of TSU-68, a novel oral multiple tyrosine kinase inhibitor, in patients with metastatic breast cancer progressing despite prior treatment with an anthracycline-containing regimen and taxane

PURPOSE

TSU-68 is a novel multiple tyrosine kinase inhibitor that inhibits vascular endothelial growth factor receptor-2, platelet-derived growth factor receptor and fibroblast growth factor receptor. TSU-68 demonstrated a strong anti-tumor effect against established human breast cancer xenografts in nude mice without apparent toxicity. We conducted a phase II study to evaluate the efficacy and safety of TSU-68 monotherapy in patients with metastatic breast cancer progressing despite prior treatment with an anthracycline-containing regimen and taxane.

METHODS

TSU-68 was administered daily at a dose of 400 mg twice a day after meals in 20 patients. The primary endpoint was objective overall response rate according to the Response Evaluation Criteria in Solid Tumors guideline version 1.0. Secondary endpoints included clinical benefit rate (complete response, partial response and stable disease lasting for at least 24 weeks), exploratory assessments of change in mRNA levels of biological markers associated with angiogenesis in tumor tissue at the end of Cycle 1, and safety of TSU-68.

RESULTS

Twenty patients were enrolled into the study from October 2002 through April 2003. TSU-68 monotherapy produced objective overall response in none of the patients; however, clinical benefit was seen in 5 % of the patients. The mRNA levels of CD31, Flt-1 and Flk-1/KDR showed a decreasing trend in all 4 patients who provided additional written informed consent for collection of tumor tissue. However, no significant difference was observed in the change in mRNA level due to the small sample size. The most common adverse drug reaction (ADR) was tumor pain (60 %); hematological ADRs rarely occurred, and they were mild in severity. Only one patient experienced grade 2 rash and no patient experienced hypertension. No patients experienced a grade 4 ADR and no episode of death related to the study treatment occurred in the 20 patients.

CONCLUSIONS

TSU-68 monotherapy produced clinical benefit in only 5 % of the patients and did not produce objective overall response; however, the treatment was well tolerated. Further evaluation of the efficacy of TSU-68 will be worthwhile because the mRNA levels of CD31, Flt-1 and Flk-1/KDR decreased in 4 patients.

Combination drug delivery approaches in metastatic breast cancer

Disseminated metastatic breast cancer needs aggressive treatment due to its reduced response to anticancer treatment and hence low survival and quality of life. Although in theory a combination drug therapy has advantages over single-agent therapy, no appreciable survival enhancement is generally reported whereas increased toxicity is frequently seen in combination treatment especially in chemotherapy. Currently used combination treatments in metastatic breast cancer will be discussed with their challenges leading to the introduction of novel combination anticancer drug delivery systems that aim to overcome these challenges. Widely studied drug delivery systems such as liposomes, dendrimers, polymeric nanoparticles, and water-soluble polymers can concurrently carry multiple anticancer drugs in one platform. These carriers can provide improved target specificity achieved by passive and/or active targeting mechanisms.

Consequence of dose scheduling of sunitinib on host immune response elements and vaccine combination therapy

Our study investigated the immunomodulatory effects of sunitinib to rationally design combinational platforms with immunotherapies for the treatment of solid tumors. Using a mouse model, we studied the effects of sunitinib given for 4 weeks at concentrations comparable to 37.5-50 mg/day in humans, followed by 2 weeks off the drug (sunitinib 4/2). We assessed the effect of differently timed combinations of sunitinib and a poxvirus-based vaccine encoding carcinoembryonic antigen (CEA) plus 3 costimulatory molecules on immune responses in CEA-transgenic (CEA-Tg) mice. Antitumor studies were performed in CEA-Tg mice bearing CEA-transfected MC38 murine colon carcinomas (MC38-CEA), treated either concurrently or sequentially with sunitinib and vaccine. In vitro, sunitinib inhibited PDGFR phosphorylation on MC38-CEA cells at concentrations similar to those biologically available during human treatment. In vivo, one cycle of sunitinib 4/2 caused bimodal immune effects: (a) decreased regulatory cells during the 4 weeks of treatment and (b) an immune-suppression rebound during the 2 weeks of treatment interruption. In a model using CEA-Tg mice bearing CEA(+) tumors, continuous sunitinib followed by vaccine increased intratumoral infiltration of antigen-specific T lymphocytes, decreased immunosuppressant T regulatory cells and myeloid-derived suppressor cells, reduced tumor volumes and increased survival. The immunomodulatory activity of continuous sunitinib administration can create a more immune-permissive environment. In combination with immunotherapies, sunitinib treatment should precede vaccine, to precondition the immune system, to maximize the response to vaccine-mediated immune enhancement.

Circulating levels of VEGFR-1 and VEGFR-2 in patients with metastatic melanoma treated with chemoimmunotherapy alone or combined with bevacizumab

There are no identified biomarkers that could predict response to antiangiogenic or traditional chemoimmunotherapy in metastatic melanoma. We hypothesized that soluble angiogenic factor receptors might help us to identify patients responsive to treatment. A series of 48 patients with stage IV melanoma participating in two phase II clinical trials were included. The trials included treatment with carboplatin, vinorelbine, and subcutaneous interleukin-2 (n=22) or treatment with bevacizumab, dacarbazine, and low-dose interferon-α2a (n=26).Serum samples were prospectively collected and soluble vascular endothelial growth factor receptor 1 (s-VEGFR-1) and 2 (s-VEGFR-2) were measured before starting the trial treatment and during response evaluation.There was a trend toward longer overall survival among patients with higher-than-median serum VEGFR-1 levels (21.3 months) compared with 12.3 months in patients with low pretreatment s-VEGFR-1 levels (P=0.146). Pretreatment s-VEGFR-2 levels did not correlate to survival. Serum VEGFR-2 levels decreased during therapy in 44% of the patients and increased in 56% of the patients. VEGFR-2 increased in 78% (14 of 18) of the patients who progressed during therapy (P=0.017). VEGFR-2 decrease was associated with clinical benefit in 65% of the patients (11 of 17) and with progression in only four patients (P=0.016).High pretreatment levels of s-VEGFR-1 are associated with improved prognosis among patients with metastatic melanoma independently on therapy, whereas increased VEGFR-2 levels during therapy are associated with disease progression. These markers might be useful in selecting patients responsive to antiangiogenic therapy.

The triple-negative subtype: new ideas for the poorest prognosis breast cancer

Triple-negative breast cancer accounts for about 15%-20% of all breast cancers. Patients with triple-negative subtype have a significantly increased risk of relapse and death. A panel of specific molecular alterations like high rate of p53 mutations, frequent loss of function of BRCA1, and several tyrosine kinase activations has been shown in this specific phenotype. An optimal chemotherapy regimen for these cancers remains to be determined, representing a major challenge for patient management. DNA alkylating agents, as cisplatin, were shown to be particularly effective in the neoadjuvant setting for patients with the disease. Targeted therapies are being successfully developed. Poly (ADP-ribose) polymerase-1 inhibitors induce tumor response as a single agent in BRCA1-mutated breast cancer and might sensitize cancer cells to cisplatin in the triple-negative subpopulation. Chemotherapy is a cornerstone of current clinical practice for this type of disease. Progress might derive from refined biology-driven phase II trials that will also integrate targeted agents with chemotherapy.

How do I treat "triple-negative" disease

OPINION STATEMENT

Over the recent years, there has been an increasing recognition that triple-negative breast cancer constitutes a separate, albeit heterogeneous, entity arising from distinct oncogenic pathways. Despite its aggressive clinical behavior, triple-negative disease responds favorably to cytotoxic chemotherapy resulting in high response rates. Nonetheless, the relapse rates are high and, in the absence of targeted therapies to significantly alter its natural history, the prognosis can be poor. Most of the trials conducted in the past that led to the formulation of the current guidelines have indiscriminately lumped triple-negative disease with receptor-positive subtypes. Therefore, there are relatively scant data regarding how standard approaches specifically apply for triple-negative disease. By virtue of its chemosensitive nature and high probability of achieving a complete pathologic response, neoadjuvant chemotherapy in early-stage/operable and locally-advanced/inoperable triple-negative disease is highly recommended. The indications for adjuvant chemotherapy are the same as in receptor-positive tumors, although endocrine therapies or agents targeting Her2 signaling have no established role in triple-negative disease. The optimal chemotherapy is not entirely clear; however, by virtue of their efficacy in breast cancer in general, anthracycline-containing regimens are the most widely used. The incorporation of taxanes in the regimen is supported by retrospective analyses. There is scant evidence to recommend any particular agent in the metastatic setting, although the combination of ixabepilone with capecitabine was shown to be active specifically in triple-negative disease. Given the uncertainty in the optimal management of triple-negative disease, the shortcomings of contemporary regimens, and the strong rationale of novel therapies, participation in clinical trials should be strongly considered at any stage of the disease.

Controlling angiogenesis in breast cancer: a systematic review of anti-angiogenic trials

PURPOSE

Angiogenesis is critical for tumor growth and a promising therapeutic target. This review will summarize and analyze data from clinical trials of anti-angiogenic agents in the treatment of breast cancer (BC).

DESIGN

A systematic search of PubMed and conference databases was performed to identify reports of randomized clinical trials investigating specific anti-angiogenic agents in the treatment of BC.

RESULTS AND DISCUSSION

Phase III trials in advanced BC have demonstrated a reduction in the risk of disease progression (22-52%), improved response rates and net improvements in progression-free survival of 1.2 to 5.5 months, but no significant improvements in overall survival with the addition of bevacizumab to chemotherapy. Results of phase III trials in early breast cancer have been inconsistent. Bevacizumab-containing regimens have also been associated with higher overall adverse event rates compared to chemotherapy alone. Phase III trials of the tyrosine kinase inhibitor sunitinib were negative, while randomized phase II trials of sorafenib and pazopanib have improved some outcomes when combined with chemotherapy or targeted therapy compared to controls. In addition to expected vascular class safety signals, tyrosine kinase inhibitors show "off-target" side effects. Ongoing clinical trials evaluating combinatorial strategies based on biological synergies and translational studies identifying biological predictors of response will be crucial to establish meaningful clinical benefits in selected BC populations.

CONCLUSION

Most trials of anti-angiogenic agents in BC have reported improved response rate and progression-free survival but no increase in overall survival compared to chemotherapy alone. Optimizing the therapeutic indices of these agents is a focus of ongoing research and will be critical to their future development.

Novel targets for VEGF-independent anti-angiogenic drugs

INTRODUCTION

In the last decades, the active research in the field of tumor angiogenesis led to the development of a class of agents providing an effective inhibition of neovessels formation through the blockade of VEGF-related pathways. More recently, the identification of several non-VEGF factors such as PDGF, FGF, HGF, angiopoietins, ALK1/endoglin, endothelis and ephrins involved in tumor angiogenesis have emphasized the need to develop agents targeting multiple pro-angiogenic pathways.

AREAS COVERED

This review aimed at summarizing the role of non-VEGF molecular pathways in targeting tumor angiogenesis. Preclinical and clinical data for investigational agents against non-VEGF targets have been reviewed emphasizing the role of combined inhibition strategies.

EXPERT OPINION

Besides the successful development of drugs providing a specific VEGF blockade, novel agents targeting alternative angiogenesis-related pathways are being tested. Although it seems that the potential clinical usefulness of these novel compounds have been not yet fully investigated, sunitinib, sorafenib, pazopanib and other multikinase inhibitors have certainly displayed encouraging results. A more in-depth clarification of anti-angiogenic agents is still needed, in order to design the best clinical setting and schedule for target-based agents and possibly anticipate potential tools to overcome the emerging issue of anti-angiogenic drug resistance.

Beyond trastuzumab: novel therapeutic strategies in HER2-positive metastatic breast cancer

The use of trastuzumab, a monoclonal antibody that targets the human epidermal growth factor receptor 2 (HER2) alteration present in 25 to 30% of breast cancers, has been associated with improved survival outcomes in both the adjuvant and metastatic settings. However, despite the robust clinical efficacy of trastuzumab in HER2-positive metastatic breast cancer (MBC), primary and secondary resistance remains a clinical challenge. Although lapatinib has demonstrated modest activity in this setting, trials reported to date have yet to demonstrate improvements in overall survival with its use. Novel therapeutic strategies to circumvent trastuzumab resistance are warranted, and agents targeting the HER, vascular endothelial growth factor, heat shock protein 90, phosphoinositide 3 kinase/Akt/mammalian target of rapamycin, and insulin-like growth factor-1 receptor pathways represent rational approaches in the management of HER2-positive disease. In this review, early-phase and emerging trial data surrounding the use of these promising agents in HER2-positive MBC will be discussed.

First-line treatment of advanced breast cancer with sunitinib in combination with docetaxel versus docetaxel alone: results of a prospective, randomized phase III study

PURPOSE

To investigate whether sunitinib plus docetaxel improves clinical outcomes for patients with human epidermal growth factor receptor 2 (HER2)/neu-negative advanced breast cancer (ABC) versus docetaxel alone.

PATIENTS AND METHODS

In this phase III study, patients were randomly assigned to open-label combination therapy (sunitinib 37.5 mg/d, days 2 to 15 every 3 weeks; and docetaxel 75 mg/m(2), day 1 every 3 weeks) or monotherapy (docetaxel 100 mg/m(2) every 3 weeks). Progression-free survival (PFS) was the primary end point.

RESULTS

Two hundred ninety-six patients were randomly assigned to combination therapy, and 297 patients were assigned to monotherapy. Median PFS times were 8.6 and 8.3 months with combination therapy and monotherapy, respectively (hazard ratio, 0.92; one-sided P = .265). The objective response rate (ORR) was significantly higher with the combination (55%) than with monotherapy (42%; one-sided P = .001). Duration of response was similar in both arms (7.5 months with the combination v 7.2 months with monotherapy). Median overall survival (OS) times were 24.8 and 25.5 months with combination therapy and monotherapy, respectively (one-sided P = .904). There were 107 deaths with the combination and 91 deaths with monotherapy. The frequency of common adverse events (AEs) was higher with the combination, as were treatment discontinuations caused by AEs.

CONCLUSION

The combination of sunitinib plus docetaxel improved ORR but did not prolong either PFS or OS compared with docetaxel alone when given to an unselected HER2/neu-negative cohort as first-line treatment for ABC. Sunitinib combination therapy may also have resulted in AEs that yield an unfavorable risk-benefit ratio. The sunitinib-docetaxel regimen evaluated in this study is not recommended for further use in ABC.

Cancer therapy modulates VEGF signaling and viability in adult rat cardiac microvascular endothelial cells and cardiomyocytes

This work was motivated by the incomplete characterization of the role of vascular endothelial growth factor-A (VEGF-A) in the stressed heart in consideration of upcoming cancer treatment options challenging the natural VEGF balance in the myocardium. We tested, if the cytotoxic cancer therapy doxorubicin (Doxo) or the anti-angiogenic therapy sunitinib alters viability and VEGF signaling in primary cardiac microvascular endothelial cells (CMEC) and adult rat ventricular myocytes (ARVM). ARVM were isolated and cultured in serum-free medium. CMEC were isolated from the left ventricle and used in the second passage. Viability was measured by LDH-release and by MTT-assay, cellular respiration by high-resolution oxymetry. VEGF-A release was measured using a rat specific VEGF-A ELISA-kit. CMEC were characterized by marker proteins including CD31, von Willebrand factor, smooth muscle actin and desmin. Both Doxo and sunitinib led to a dose-dependent reduction of cell viability. Sunitinib treatment caused a significant reduction of complex I and II-dependent respiration in cardiomyocytes and the loss of mitochondrial membrane potential in CMEC. Endothelial cells up-regulated VEGF-A release after peroxide or Doxo treatment. Doxo induced HIF-1α stabilization and upregulation at clinically relevant concentrations of the cancer therapy. VEGF-A release was abrogated by the inhibition of the Erk1/2 or the MAPKp38 pathway. ARVM did not answer to Doxo-induced stress conditions by the release of VEGF-A as observed in CMEC. VEGF receptor 2 amounts were reduced by Doxo and by sunitinib in a dose-dependent manner in both CMEC and ARVM. In conclusion, these data suggest that cancer therapy with anthracyclines modulates VEGF-A release and its cellular receptors in CMEC and ARVM, and therefore alters paracrine signaling in the myocardium.

Antiangiogenic agents increase breast cancer stem cells via the generation of tumor hypoxia

Antiangiogenic therapy has been thought to hold significant potential for the treatment of cancer. However, the efficacy of such treatments, especially in breast cancer patients, has been called into question, as recent clinical trials reveal only limited effectiveness of antiangiogenic agents in prolonging patient survival. New research using preclinical models further suggests that antiangiogenic agents actually increase invasive and metastatic properties of breast cancer cells. We demonstrate that by generating intratumoral hypoxia in human breast cancer xenografts, the antiangiogenic agents sunitinib and bevacizumab increase the population of cancer stem cells. In vitro studies revealed that hypoxia-driven stem/progenitor cell enrichment is primarily mediated by hypoxia-inducible factor 1α. We further show that the Akt/β-catenin cancer stem cell regulatory pathway is activated in breast cancer cells under hypoxic conditions in vitro and in sunitinib-treated mouse xenografts. These studies demonstrate that hypoxia-driven cancer stem cell stimulation limits the effectiveness of antiangiogenic agents, and suggest that to improve patient outcome, these agents might have to be combined with cancer stem cell-targeting drugs.

A phase I study of sunitinib in combination with FOLFIRI in patients with untreated metastatic colorectal cancer

BACKGROUND

This study evaluated the maximum tolerated dose (MTD) of sunitinib, a multitargeted tyrosine kinase inhibitor, combined with FOLFIRI (irinotecan 180 mg/m2 given over 90 min i.v. and l-leucovorin 200 mg/m2 given over 120 min on day 1, followed by 5-FU 400 mg/m2 bolus and then 2400 mg/m2 infused over 46 h) in untreated metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

In this multicentre, phase I, open-label, dose-finding trial, FOLFIRI was administered every 2 weeks. Two sunitinib regimens were explored: Schedule 4/2 (4 weeks on, 2 weeks off; 37.5 and 50 mg/day) and continuous daily dosing (CDD; 37.5 and 25 mg/day). Dose-limiting toxic toxicities (DLTs) were evaluated during weeks 1-6. Efficacy was a secondary objective.

RESULTS

Thirty-seven patients were enrolled. The 37.5 mg/day Schedule 4/2 cohort had zero of six DLTs, was expanded by 15 patients and declared the MTD. The MTD was exceeded at all other sunitinib doses and schedules; DLTs included febrile neutropenia (n=1), grade 4 neutropenia (n=4) and grade 3 deep vein thrombosis with grade 4 neutropenia (n=1). At the MTD, non-haematologic grade 3/4 adverse events with a frequency of >10% were diarrhoea, vomiting and lethargy, and the objective response rate was 57.9% (95% confidence interval 33.5-79.7).

CONCLUSIONS

The MTD of sunitinib combined with FOLFIRI in chemotherapy-naive mCRC was 37.5 mg/day on Schedule 4/2. CDD of sunitinib at 37.5 or 25 mg/day plus FOLFIRI was not feasible.

Triple Negative Breast Cancer - An Overview

Triple Negative Breast Cancer (TNBC) is a heterogeneous disease that based on immunohistochemistry (IHC) is estrogen receptor (ER) negative, progesterone receptor (PR) negative and human epidermal growth factor receptor 2 (HER2) negative. TNBC is typically observed in young AA women and Hispanic women who carry a mutation in the BRCA1 gene. TNBC is characterized by a distinct molecular profile, aggressive nature and lack of targeted therapies. The purpose of this article is to review the current and future novel signalling pathways as therapeutic approaches to TNBC. Recent Identification of a new BRCA1 trafficking pathway holds promise in the future for the development of targeted therapies for TNBC.

Basal breast cancer: a complex and deadly molecular subtype

During the last decade, gene expression profiling of breast cancer has revealed the existence of five molecular subtypes and allowed the establishment of a new classification. The basal subtype, which represents 15-25% of cases, is characterized by an expression profile similar to that of myoepithelial normal mammary cells. Basal tumors are frequently assimilated to triple-negative (TN) breast cancers. They display epidemiological and clinico-pathological features distinct from other subtypes. Their pattern of relapse is characterized by frequent and early relapses and visceral locations. Despite a relative sensitivity to chemotherapy, the prognosis is poor. Recent characterization of their molecular features, such as the dysfunction of the BRCA1 pathway or the frequent expression of EGFR, provides opportunities for optimizing the systemic treatment. Several clinical trials dedicated to basal or TN tumors are testing cytotoxic agents and/or molecularly targeted therapies. This review summarizes the current state of knowledge of this aggressive and hard-to-treat subtype of breast cancer.

Pharmacokinetics, distribution, and metabolism of [14C]sunitinib in rats, monkeys, and humans

Sunitinib is an oral multitargeted tyrosine kinase inhibitor approved for the treatment of advanced renal cell carcinoma, imatinib-refractory gastrointestinal stromal tumor, and advanced pancreatic neuroendocrine tumors. The current studies were conducted to characterize the pharmacokinetics, distribution, and metabolism of sunitinib after intravenous and/or oral administrations of [(14)C]sunitinib in rats (5 mg/kg i.v., 15 mg/kg p.o.), monkeys (6 mg/kg p.o.), and humans (50 mg p.o.). After oral administration, plasma concentration of sunitinib and total radioactivity peaked from 3 to 8 h. Plasma terminal elimination half-lives of sunitinib were 8 h in rats, 17 h in monkeys, and 51 h in humans. The majority of radioactivity was excreted to the feces with a smaller fraction of radioactivity excreted to urine in all three species. The bioavailability in female rats was close to 100%, suggesting complete absorption of sunitinib. Whole-body autoradioluminography suggested radioactivity was distributed throughout rat tissues, with the majority of radioactivity cleared within 72 h. Radioactivity was eliminated more slowly from pigmented tissues. Sunitinib was extensively metabolized in all species. Many metabolites were detected both in urine and fecal extracts. The main metabolic pathways were N-de-ethylation and hydroxylation of indolylidene/dimethylpyrrole. N-Oxidation/hydroxylation/desaturation/deamination of N,N'-diethylamine and oxidative defluorination were the minor metabolic pathways. Des-ethyl metabolite M1 was the major circulating metabolite in all three species.

A phase II study of sunitinib as a second-line treatment in advanced biliary tract carcinoma: a multicentre, multinational study

BACKGROUND

Biliary tract carcinoma (BTC) is rare in the West, but not uncommon in Asia and is a highly fatal malignancy. VEGF expression is related with poor outcome in patients with BTC. Therefore, we conducted a phase II study to evaluate the efficacy and safety of sunitinib as second-line treatment.

METHODS

This was a prospective, single-arm, multicentre, multinational study. Patients with unresectable, metastatic BTC who progressed after first-line chemotherapy were eligible. Sunitinib was administered at 37.5mg once daily continuously with 4-week cycle. The primary end point was the time to progression (TTP).

RESULTS

Between May 2009 and October 2010, a total of 56 patients were enrolled from three countries. The median age was 55 years (range 38-75) and male to female ratio was 37:19. Median TTP was 1.7 months (95% confidence interval (CI) 1.0-2.4). The objective response rate was 8.9% (5 partial response) and disease control rate was 50.0%. (23 stable disease) Grade 3-4 toxicities were observed in 46.4% of the patients with neutropenia and thrombocytopenia being the most frequent (21.4%).

CONCLUSIONS

This phase II study suggests that sunitinib monotherapy demonstrated marginal efficacy in metastatic BTC patients although toxicity should be concerned in Asian population.

Treatment of HER2-positive breast cancer: current status and future perspectives

The advent of HER2-directed therapies has significantly improved the outlook for patients with HER2-positive early stage breast cancer. However, a significant proportion of these patients still relapse and die of breast cancer. Trials to define, refine and optimize the use of the two approved HER2-targeted agents (trastuzumab and lapatinib) in patients with HER2-positive early stage breast cancer are ongoing. In addition, promising new approaches are being developed including monoclonal antibodies and small-molecule tyrosine kinase inhibitors targeting HER2 or other HER family members, antibodies linked to cytotoxic moieties or modified to improve their immunological function, immunostimulatory peptides, and targeting the PI3K and IGF-1R pathways. Improved understanding of the HER2 signaling pathway, its relationship with other signaling pathways and mechanisms of resistance has also led to the development of rational combination therapies and to a greater insight into treatment response in patients with HER2-positive breast cancer. Based on promising results with new agents in HER2-positive advanced-stage disease, a series of large trials in the adjuvant and neoadjuvant settings are planned or ongoing. This Review focuses on current treatment for patients with HER2-positive breast cancer and aims to update practicing clinicians on likely future developments in the treatment for this disease according to ongoing clinical trials and translational research.

Emerging drugs in metastatic breast cancer: an update

INTRODUCTION

The incidence of breast cancer at an advanced stage has decreased in the modern world due to screening programs and usage of novel chemotherapy agents at an adjuvant setting. Recurrence is the major problem seen in > 50% of breast cancer patients diagnosed at an early stage. Developing new drugs for metastatic breast cancer is a huge and challenging research area.

AREAS COVERED

Emerging drugs showed positive results in clinical studies and agents in routine clinical usage are updated. Current treatment strategies as a combination of biologic agents and overcoming drug resistance are discussed. Literature search is made from PubMed, ASCO and San Antonio Breast Cancer Symposium Meeting abstracts.

EXPERT OPINION

A number of drugs caused survival benefit for advanced breast cancer. Hundreds of new studies with tens of agents are conducted for treatment of metastatic breast cancer. Tumor resistance and treatment related toxicities are unavoidable which are two main search areas for improving metastatic breast cancer management. Understanding the pathways of genesis and progression yielded many targets for treatment. However, cure in metastatic breast cancer is still a far aim and new agents and treatment strategies are needed.

The paradox of triple negative breast cancer: novel approaches to treatment

Breast cancer that lacks expression of estrogen/progesterone receptors and overexpression of the human epidermal growth factor receptor2 (HER2), i.e. triple-negative breast cancer (TNBC), is not amenable to current targeted therapies and carries a poor prognosis. This review discusses the natural history of TNBC and published literature in the relevant treatment landscape, with a focus on newer therapies. Compared with other subtypes of breast cancer, TN tumors have higher response rates to neoadjuvant chemotherapy; however, this advantage is not clearly translated into the metastatic setting and has not improved these patients' overall survival. Numerous cytotoxic and targeted strategies have demonstrated efficacy or are under investigation. Strategies showing promise in this difficult-to-treat group of patients include cytotoxic therapy with platinum-containing agents, ixabepilone, and novel targeted approaches such as poly(ADP-ribose) polymerase inhibitors.

Acalypha wilkesiana extracts induce apoptosis by causing single strand and double strand DNA breaks

ETHNOPHARMACOLOGICAL RELEVANCE

The seeds of Acalypha wilkesiana have been used empirically by traditional healers in Southwest Nigeria together with other plants as a powder mixture to treat patients with breast tumours and inflammation.

AIM OF THE STUDY

There is an increasing interest among researchers in searching for new anticancer drugs from natural resources, particularly plants. This study aimed to investigate the anticancer properties of Acalypha wilkesiana extracts and the characteristics of DNA damage against brain and lung cancer cells.

MATERIALS AND METHODS

The antiproliferative activity of Acalypha wilkesiana extracts (ethyl acetate, hexane, and ethanol) was examined on human glioma (U87MG), human lung carcinoma (A549), and human lung fibroblast (MRC5) cells.

RESULTS

Cell viability MTT assay revealed that ethyl acetate extract of the plant possessed significant antiproliferative effects against both U87MG (GI(50)=28.03 ± 6.44 μg/ml) and A549 (GI(50)=89.63 ± 2.12 μg/ml) cells (p value<0.0001). The hexane extract was found to exhibit crucial antiproliferative effects on U87MG (GI(50)=166.30 ± 30.50 μg/ml) (p value<0.0001) but not on A549 cells. Neither plant extract possessed noticeable antiproliferative effects on the non-cancerous MRC5 cells (GI(50)>300 μg/ml). The ethanol extract showed no antiproliferative effects on any cell line examined. Haematoxylin & Eosin (H & E) staining and single cell gel electrophoresis (SCGE) comet assay confirmed that plant extract-treated cells underwent apoptosis and not necrosis. SCGE comet assays confirmed that plant extracts caused both single strand (SSB) and double strand (DSB) DNA breaks that led to the execution of apoptosis.

CONCLUSION

The extracts (especially ethyl acetate and hexane) of Acalypha wilkesiana possess valuable cytotoxic effects that trigger apoptosis in U87MG and A549 cancer cells through induction of DNA SSBs and DSBs.

Treatment of triple-negative metastatic breast cancer: toward individualized targeted treatments or chemosensitization?

Triple-negative [estrogen receptor (ER)-/progesterone receptor (PR)-/HER2-] breast cancers account for ~15% of overall breast cancers. Triple-negative breast cancers demonstrate a panel of specific molecular alterations including a high rate of p53 mutations, frequent loss of function of BRCA1, phosphatase and tensin homolog (PTEN) loss and a specific panel of tyrosine kinase activation [fibroblast growth factor receptor 2 (FGFR2)]. This molecular entity is considered as sensitive to chemotherapy in the adjuvant setting. When metastatic, the disease is usually aggressive and drug resistant, leading to cancer death within 18 months for the majority of patients. There is no evidence from randomized trials that triple-negative breast cancers have a different sensitivity to specific chemotherapy compared with other molecular classes. Similar findings have been reported for bevacizumab. Several recent research efforts have focused on this entity in the last few years. DNA alkylating agents have shown promising activity in the neoadjuvant setting, but no evidence from a phase III trial currently supports its use. Several targeted therapies are also being successfully developed. Poly(ADP ribose) polymerase 1 (PARP1) inhibitors induce tumor response as a single agent in BRCA1-mutated breast cancer, and could sensitize cisplatin in the whole triple negative population. Several other targeted agents are being developed in this setting, including epidermal growth factor receptor (EGFR), FGFR2, mammalian target of rapamycin (mTOR) and NOTCH inhibitors.

A nation-wide multicenter 10-year (1999-2008) retrospective clinical epidemiological study of female breast cancer in China

BACKGROUND

According to the very limited cancer registry, incidence and mortality rates for female breast cancer in China are regarded to be increasing especially in the metropolitan areas. Representative data on the breast cancer profile of Chinese women and its time trend over years are relatively rare. The aims of the current study are to illustrate the breast cancer profile of Chinese women in time span and to explore the current treatment approaches to female breast cancer.

METHODS

This was a hospital-based nation-wide and multi-center retrospective study of female primary breast cancer cases. China was divided into 7 regions according to the geographic distribution; from each region, one tertiary hospital was selected. With the exception of January and February, one month was randomly selected to represent each year from year 1999 to 2008 at every hospital. All inpatient cases within the selected month were reviewed and related information was collected based on the designed case report form (CRF). The Cancer Hospital/Institute, Chinese Academy of Medical Sciences (CICAMS) was the leading hospital in this study.

RESULTS

Four-thousand two-hundred and eleven cases were randomly selected from the total pool of 45,200 patients and were included in the analysis. The mean age at diagnosis was 48.7 years (s.d. = 10.5 yrs) and breast cancer peaked in age group 40-49 yrs (38.6%). The most common subtype was infiltrating ductal carcinoma (86.5%). Clinical stage I & II accounted for 60.6% of 4,211 patients. Three-thousand five-hundred and thirty-four cases had estrogen receptor (ER) and progestin receptor (PR) tests, among them, 47.9% were positive for both. Two-thousand eight-hundred and forty-nine cases had human epidermal growth factor receptor 2(HER-2) tests, 25.8% of them were HER-2 positive. Among all treatment options, surgery (96.9% (4,078/4,211)) was predominant, followed by chemotherapy (81.4% (3,428/4,211). Much less patients underwent radiotherapy (22.6% (952/4,211)) and endocrine therapy (38.0% (1,599/4,211)).

CONCLUSIONS

The younger age of breast cancer onset among Chinese women and more advanced tumor stages pose a great challenge. Adjuvant therapy, especially radiotherapy and endocrine therapy are of great unmet needs.

Basal phenotype breast cancer: implications for treatment and prognosis

Breast cancer is the most common malignancy in females. The origins and biology of breast carcinomas remain unclear. Cellular and molecular heterogeneity results in different distinct groups of tumors with different clinical behavior and prognosis. Gene expression profiling has delineated five molecular subtypes based on similarities in gene expression: luminal A, luminal B, HER2 overexpressing, normal-like and basal-like. Basal-like breast cancer (BLBC) lacks estrogen receptor, progesterone receptor and HER2 expression, and comprises myoepithelial cells. Specific features include high proliferative rate, rapid growth, early recurrence and decreased overall survival. BLBC is associated with ductal carcinoma in situ, BRCA1 mutation, brain and lung metastasis, and negative axillary lymph nodes. Currently, chemotherapy is the only therapeutic choice, but demonstrates poor outcomes. There is an overlap in definition between triple-negative breast cancer and BLBC due to the triple-negative profile of BLBC. Despite the molecular and clinical similarities, the two subtypes respond differently to neoadjuvant therapy. Although particular morphologic, genetic and clinical features of BLBC have been identified, a variety of definitions among studies accounts for the contradictory results reported. In this article the molecular morphological and histopathological profile, the clinical behavior and the therapeutic options of BLBC are presented, with emphasis on the discordant findings among studies.