Iniparib plus chemotherapy in metastatic triple-negative breast cancer

Alternative Splicing in Breast Cancer and the Potential Development of Therapeutic Tools

Alternative splicing is a key molecular mechanism now considered as a hallmark of cancer that has been associated with the expression of distinct isoforms during the onset and progression of the disease. The leading cause of cancer-related deaths in women worldwide is breast cancer, and even when the role of alternative splicing in this type of cancer has been established, the function of this mechanism in breast cancer biology is not completely decoded. In order to gain a comprehensive view of the role of alternative splicing in breast cancer biology and development, we summarize here recent findings regarding alternative splicing events that have been well documented for breast cancer evolution, considering its prognostic and therapeutic value. Moreover, we analyze how the response to endocrine and chemical therapies could be affected due to alternative splicing and differential expression of variant isoforms. With all this knowledge, it becomes clear that targeting alternative splicing represents an innovative approach for breast cancer therapeutics and the information derived from current studies could guide clinical decisions with a direct impact in the clinical advances for breast cancer patients nowadays.

Therapeutic Implications of the Molecular and Immune Landscape of Triple-Negative Breast Cancer

Treatment and management of breast cancer imposes a heavy burden on public health care, and incidence rates continue to increase. Breast cancer is the most common female neoplasia and primary cause of death among women worldwide. The recognition of breast cancer as a complex and heterogeneous disease, comprising different molecular entities, was a landmark in our understanding of this malignancy. Valuing the impact of the molecular characteristics on tumor behavior enabled a better assessment of a patient's prognosis and increased the predictive power to therapeutic response and clinical outcome. Molecular heterogeneity is also prominent in the triple-negative breast cancer subtype, and is reflected by the distinct prognostic and patient's sensitivity to treatment, being chemotherapy the only systemic treatment currently available. From a therapeutic perspective, gene expression profiling of triple-negative tumors has notably contributed to the exploration of new druggable targets and brought to light the need to align these patients to the various therapies according to their triple-negative subtype. Additionally, the higher amount of tumor infiltrating lymphocytes, and the prevalence of an increased expression of PD-1 receptor and its ligand, PD-L1, in triple-negative tumors, created a new treatment opportunity with immune checkpoint inhibitors. This manuscript addresses the current knowledge on the molecular and immune profiles of breast cancer, and its impact on the development of targeted therapies, with a particular emphasis on the triple-negative subtype.

How many diseases is triple negative breast cancer: the protagonism of the immune microenvironment

Triple negative breast cancer (TNBC) is a type of breast cancer (BC) that does not express the oestrogen and the progesterone receptors and the human epidermal growth factor receptor type 2 (HER2). Since there are no positive markers to reliably classify TNBC, these tumours are not yet treated with targeted therapies. Perhaps for this reason they are the most aggressive form of breast carcinomas. However, the clinical observation that these patients do not carry a uniformly dismal prognosis, coupled with data coming from pathology and epidemiology, suggests that this negative definition is not capturing a single clinical entity, but several. We critically evaluate this evidence in this paper, reviewing clinical and epidemiological data and new studies that aim to subclassify TNBC. Moreover, evidence on the role of tumour infiltrating lymphocytes (TILs) on TNBC progression, response to chemotherapy and patient outcome have been published. The heterogeneity, observed even at TILs level, highlights the idea that TNBC is much more than a single disease with a unique treatment. The exploration of the immune environment present at the tumour site could indeed help in answering the question 'How many diseases is TNBC' and will help to define prognosis and eventually develop new therapies, by stimulating the immune effector cells or by inhibiting immunological repressor molecules. In this review, we focus on the prospect of the patient's diverse immune signatures within the tumour as potential biomarkers and how they could be modulated to fight the disease.

Cancer-derived exosomes as a delivery platform of CRISPR/Cas9 confer cancer cell tropism-dependent targeting

An intracellular delivery system for CRISPR/Cas9 is crucial for its application as a therapeutic genome editing technology in a broad range of diseases. Current vehicles carrying CRISPR/Cas9 limit in vivo delivery because of low tolerance and immunogenicity; thus, the in vivo delivery of genome editing remains challenging. Here, we report that cancer-derived exosomes function as natural carriers that can efficiently deliver CRISPR/Cas9 plasmids to cancer. Compared to epithelial cell-derived exosomes, cancer-derived exosomes provide potential vehicles for effective in vivo delivery via selective accumulation in ovarian cancer tumors of SKOV3 xenograft mice, most likely because of their cell tropism. CRISPR/Cas9-loaded exosomes can suppress expression of poly (ADP-ribose) polymerase-1 (PARP-1), resulting in the induction of apoptosis in ovarian cancer. Furthermore, the inhibition of PARP-1 by CRISPR/Cas9-mediated genome editing enhances the chemosensitivity to cisplatin, showing synergistic cytotoxicity. Based on these results, tumor-derived exosomes may be very promising for cancer therapeutics in the future.

Cancer-Associated Fibroblasts Autophagy Enhances Progression of Triple-Negative Breast Cancer Cells

BACKGROUND Cancer-associated fibroblasts (CAFs) are key factors in malignant tumor initiation, progression, and metastasis. However, the effect of CAFs autophagy on triple-negative breast cancer (TNBC) cells is not clear. In this study, the growth effect of TNBC cells regulated by CAFs autophagy was evaluated. MATERIAL AND METHODS CAFs were obtained from invasive TNBC tumors and identified by Western blot and immunofluorescence staining assay. CAFs were co-cultured with TNBC cells, and migration and invasion were evaluated by Matrigel-coated Transwell and Transwell inserts. TNBC cells growth was detected by MTT assay, and epithelial-mesenchymal transition (EMT) regulated by CAFs was evaluated by Western blot assay. RESULTS CAFs were identified by the high expression of α-smooth muscle actin (α-SMA) protein. Autophagy-relevant Beclin 1 and LC3-II/I protein conversion levels in CAFs were higher than those in NFs (P<0.05). TNBC cells migration, invasion, and proliferation levels were significantly improved in the CAFs-conditioned medium (CAFs-CM) group, compared with the other 3 groups (P<0.05). TNBC cells vimentin and N-cadherin protein levels were upregulated and E-cadherin protein level was downregulated in the CAFs-CM group compared with the control group (P<0.05). Further study indicated b-catenin and P-GSK-3β protein levels, which are the key proteins in the Wnt/β-catenin pathway, were upregulated in the CAFs-CM group compared with the control group (P<0.05). CONCLUSIONS Our data demonstrated CAFs autophagy can enhance TNBC cell migration, invasion, and proliferation, and CAFs autophagy can induce TNBC cells to engage in the EMT process through the Wnt/β-catenin pathway.

MicroRNA-519a-3p mediates apoptosis resistance in breast cancer cells and their escape from recognition by natural killer cells

Aggressive breast cancer is associated with poor patient outcome and characterized by the development of tumor cell variants that are able to escape from control of the immune system or are resistant to targeted therapies. The complex molecular mechanisms leading to immune escape and therapy resistance are incompletely understood. We have previously shown that high miR-519a-3p levels are associated with poor survival in breast cancer. Here, we demonstrate that miR-519a-3p confers resistance to apoptosis induced by TRAIL, FasL and granzyme B/perforin by interfering with apoptosis signaling in breast cancer cells. MiR-519a-3p diminished the expression of its direct target genes for TRAIL-R2 (TNFRSF10B) and for caspase-8 (CASP8) and its indirect target gene for caspase-7 (CASP7), resulting in reduced sensitivity and tumor cell apoptosis in response to apoptotic stimuli. Furthermore, miR-519a-3p impaired tumor cell killing by natural killer (NK) cells via downregulation of the NKG2D ligands ULBP2 and MICA on the surface of tumor cells that are crucial for the recognition of these tumor cells by NK cells. We determined that miR-519a-3p was overexpressed in more aggressive mutant TP53 breast cancer that was associated with poor survival. Furthermore, low levels of TRAIL-R2, caspase-7 and caspase-8 correlated with poor survival, suggesting that the inhibitory effect of miR-519a-3p on TRAIL-R2 and caspases may have direct clinical relevance in lowering patient’s prognosis. In conclusion, we demonstrate that miR-519a-3p is a critical factor in mediating resistance toward cancer cell apoptosis and impairing tumor cell recognition by NK cells. This joint regulation of apoptosis and immune cell recognition through miR-519a-3p supports the hypothesis that miRNAs are key regulators of cancer cell fate, facilitating cancer progression and evasion from immunosurveillance at multiple and interconnected levels.

A network meta-analysis on the efficacy of targeted agents in combination with chemotherapy for treatment of advanced/metastatic triple-negative breast cancer

OBJECTIVE

Our network meta-analysis aimed to determine the assistant efficacy of targeted therapy in combined with chemotherapy for advanced/metastatic triple-negative breast cancer (TNBC).

RESULTS

A total of 15 randomized controlled trials (RCTs), involving 2,410 patients, met our inclusion criteria. Eight targeted agents involving 11 treatment arms were included. The methodological quality of included RCTs was acceptable. The results of direct comparisons showed that progression-free survival (PFS) was significantly longer with bevacizumab+chemotherapy when compared to chemotherapy alone (hazard ratio [HR] = 0.62, 95% credible intervals [CrI]: 0.41-0.87). However, there were no statistically significant differences for all other direct comparison groups. The results of indirect comparison of different targeted agents revealed no significant differences regarding all outcomes of interest. According to ranking probabilities, all outcomes favored bevacizumab+chemotherapy and veliparib+chemotherapy. Bayesian and Frequentist network meta-analysis showed similar results, and the probability of bias of small-study effects was small.

MATERIALS AND METHODS

A comprehensive literature search in PubMed, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science (via ISI Web of Knowledge), BIOSIS Previews (via ISI Web of Knowledge), and Chemical Abstracts (CA) was conducted to identify RCTs involving targeted agents in the treatment of advanced/metastatic TNBC. Two reviewers independently extracted related data and assessed the risk of bias of included studies. Bayesian network meta-analysis was conducted using R-3.3.2 software.

CONCLUSIONS

Limited evidence showed that targeted agents combined with chemotherapy for advanced/metastatic TNBC were slightly effective. Further investigation of targeted therapies for TNBC is required to improve patient outcomes. The registration number was CRD42014014299.

Novel therapeutic strategies in the treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous subtype of breast cancer that is defined by negative estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status. Treating patients with TNBC remains clinically challenging, as patients are not candidates for endocrine or HER2-directed therapy. As a result, chemotherapy with traditional agents such as anthracyclines and taxanes remains the only available option with moderate success. Recent discoveries have revealed that TNBC is a heterogeneous disease at the clinical, histological and molecular levels. The use of biomarkers to identify distinct subsets of TNBC that derive the greatest benefit from presently approved as well as novel therapeutics has become the main focus of current research. The aim of this review is to explore the clinical and biological complexity of TNBC as well as identify novel therapeutic options that target the various molecular subsets of TNBC.

Repurposing DNA repair factors to eradicate tumor cells upon radiotherapy

Cancer is the leading cause of death worldwide. Almost 50% of all cancer patients undergo radiation therapy (RT) during treatment, with varying success. The main goal of RT is to kill tumor cells by damaging their DNA irreversibly while sparing the surrounding normal tissue. The outcome of RT is often determined by how tumors recognize and repair their damaged DNA. A growing body of evidence suggests that tumors often show abnormal expression of DNA double-strand break (DSB) repair genes that are absent from normal cells. Defects in a specific DNA repair pathway make tumor cells overly dependent on alternative or backup pathways to repair their damaged DNA. These tumor cell-specific abnormalities in the DNA damage response (DDR) machinery can potentially be used as biomarkers for treatment outcomes or as targets for sensitization to ionizing radiation (IR). An improved understanding of genetic or epigenetic alterations in the DNA repair pathways specific to cancer cells has paved the way for new treatments that combine pharmacological exploitation of tumor-specific molecular vulnerabilities with IR. Inhibiting DNA repair pathways has the potential to greatly enhance the therapeutic ratio of RT. In this review, we will discuss DNA repair pathways in active cells and how these pathways are deregulated in tumors. We will also describe the impact of targeting cancer-specific aberrations in the DDR as a treatment strategy to improve the efficacy of RT. Finally, we will address the current roadblocks and future prospects of these approaches.

Dual-targeted hybrid nanoparticles of synergistic drugs for treating lung metastases of triple negative breast cancer in mice

Lung metastasis is the major cause of death in patients with triple negative breast cancer (TNBC), an aggressive subtype of breast cancer with no effective therapy at present. It has been proposed that dual-targeted therapy, ie, targeting chemotherapeutic agents to both tumor vasculature and cancer cells, may offer some advantages. The present work was aimed to develop a dual-targeted synergistic drug combination nanomedicine for the treatment of lung metastases of TNBC. Thus, Arg-Gly-Asp peptide (RGD)-conjugated, doxorubicin (DOX) and mitomycin C (MMC) co-loaded polymer-lipid hybrid nanoparticles (RGD-DMPLN) were prepared and characterized. The synergism between DOX and MMC and the effect of RGD-DMPLN on cell morphology and cell viability were evaluated in human MDA-MB-231 cells in vitro. The optimal RGD density on nanoparticles (NPs) was identified based on the biodistribution and tumor accumulation of the NPs in a murine lung metastatic model of MDA-MB-231 cells. The microscopic distribution of RGD-conjugated NPs in lung metastases was examined using confocal microscopy. The anticancer efficacy of RGD-DMPLN was investigated in the lung metastatic model. A synergistic ratio of DOX and MMC was found in the MDA-MB-231 human TNBC cells. RGD-DMPLN induced morphological changes and enhanced cytotoxicity in vitro. NPs with a median RGD density showed the highest accumulation in lung metastases by targeting both tumor vasculature and cancer cells. Compared to free drugs, RGD-DMPLN exhibited significantly low toxicity to the host, liver and heart. Compared to non-targeted DMPLN or free drugs, administration of RGD-DMPLN (10 mg/kg, iv) resulted in a 4.7-fold and 31-fold reduction in the burden of lung metastases measured by bioluminescence imaging, a 2.4-fold and 4.0-fold reduction in the lung metastasis area index, and a 35% and 57% longer median survival time, respectively. Dual-targeted RGD-DMPLN, with optimal RGD density, significantly inhibited the progression of lung metastasis and extended host survival.

Effects of TPX2 gene on radiotherapy sensitization in breast cancer stem cells

The present study explored the link between the targeting protein for Xenopus kinesin-like protein 2 (TPX2) gene and breast tumor stem cells in order to screen novel radiosensitizers. Expression of TPX2 protein and gene in breast cancer cells was analyzed by western blot analysis and RT-PCR. Three kinds of broad-spectrum sensitizers were selected and their effects on radiotherapy were analyzed by immunohistochemistry in breast tumor stem cells. TPX2 gene and protein were expressed in breast tumor cells and increased gradually along with the expression of cancer cell differentiation; 25 mg/l lovastatin showed best radio-sensitizing effects on breast cancer cells. Furthermore, immunohistochemical results showed that the positive rate of breast cancer cells processed by 25 mg/l lovastatin were significantly decreased. In conclusion, TPX2 gene is closely related to the development of breast cancer stem cells. Moreover, the sensitizing effects of lovastatin on breast tumor stem cells are the result of its influence on the TPX2 gene.

Selective Inhibitors of Nuclear Export (SINE) compounds block proliferation and migration of triple negative breast cancer cells by restoring expression of ARRDC3

Arrestin-related domain-containing protein-3 (ARRDC3) is one of 6 mammalian arrestins, which suppresses metastasis by inducing degradation of phosphorylated β2-adrenergic receptor (β2 AR) and integrin β4 (ITG β4). Our previous studies demonstrated that expression of ARRDC3 is epigentically silenced in Triple Negative Breast Cancer (TNBC) cells, and the forced expression of ARRDC3 significantly reduced the invasive potential of TNBC cells. In the current study, we found that Selective Inhibitors of Nuclear Export (SINE) compounds (KPT-185 and selinexor (KPT-330)) restore ARRDC3 expression in TNBC cell lines (MDA-MB-231 and MDA-MB-468) at both the mRNA and protein level in a dose and time course dependent manner. SINE compounds inhibit the proliferation, pro-invasive migration and anchorage independent growth of the TNBC cells by restoring ARRDC3 expression. We found that ARRDC3 expression is lower in TNBC cell lines than those of luminal breast cancer cell lines, and inversely correlated with IC_50s of selinexor. Analysis of tissue microarray confirmed that ARRDC3 expression in patient samples is significantly lower in the majority of TNBC tumors relative to normal tissue. In vivo, selinexor inhibited the tumor growth of MDA-MB-231 xenografts by nearly 100% compared with vehicle treated animals. Furthermore, immunohistochemical analysis of TNBC tumors from selinexor treated mice revealed increased ARRDC3 expression versus vehicle treated animals. Our results suggest that restoration of ARRDC3 expression is an important antineoplastic mechanism of SINE compounds in TNBC, and therefore selinexor could be an effective treatment option for breast tumors with down-regulated ARRDC3.

18F-FDG-PET/CT for systemic staging of patients with newly diagnosed ER-positive and HER2-positive breast cancer

OBJECTIVES

This study assesses ¹⁸F-FDG-PET/CT for patients with newly diagnosed estrogen receptor-positive/human epidermal growth factor receptor-negative (ER+/HER2-) and human epidermal growth factor receptor-positive (HER2+) breast cancer.

METHODS

In this Institutional Review Board-approved retrospective study, our Healthcare Information System was screened for patients with ER+/HER2- and HER2+ breast cancer who underwent ¹⁸F-FDG-PET/CT prior to systemic or radiation therapy. The initial stage was determined from mammography, ultrasound, magnetic resonance imaging, and/or surgery.¹⁸F-FDG-PET/CT was evaluated to identify unsuspected extra-axillary regional nodal and distant metastases. The proportion of patients upstaged overall and stratified by stage and receptor phenotypes was calculated along with confidence intervals (CI).

RESULTS

A total of 238 patients with ER+/HER2- and 245 patients with HER2+ who met inclusion criteria were evaluated. For patients with ER+/HER2-breast cancer, ¹⁸F-FDG-PET/CT revealed unsuspected distant metastases in 3/71 (4%) initial stage IIA, 13/95 (14%) stage IIB, and 15/57 (26%) stage III. For patients with HER2+ breast cancer, ¹⁸F-FDG-PET/CT revealed unsuspected distant metastases in 3/72 (4%) initial stage IIA, 13/93 (14%) stage IIB, and 13/59 (22%) stage III. The overall upstaging rate for IIB was 14% (95% confidence interval (CI): 9-20%).

CONCLUSIONS

¹⁸F-FDG-PET/CT revealed distant metastases in 14% (95% CI: 9-20%) of patients with stage IIB ER+/HER2- and HER2+ breast cancer, which is similar to upstaging rates previously seen in patients with stage IIB triple-negative breast cancer (15%, 95% CI: 9-24%). The detection of unsuspected distant metastases in these patients alters treatment and prognosis. NCCN guidelines should consider adding patients with stage IIB breast cancer for consideration of systemic staging with ¹⁸F-FDG-PET/CT at the time of initial diagnosis.

Targeted therapies in breast cancer: New challenges to fight against resistance

Breast cancer is the most common type of cancer found in women and today represents a significant challenge to public health. With the latest breakthroughs in molecular biology and immunotherapy, very specific targeted therapies have been tailored to the specific pathophysiology of different types of breast cancers. These recent developments have contributed to a more efficient and specific treatment protocol in breast cancer patients. However, the main challenge to be further investigated still remains the emergence of therapeutic resistance mechanisms, which develop soon after the onset of therapy and need urgent attention and further elucidation. What are the recent emerging molecular resistance mechanisms in breast cancer targeted therapy and what are the best strategies to apply in order to circumvent this important obstacle? The main scope of this review is to provide a thorough update of recent developments in the field and discuss future prospects for preventing resistance mechanisms in the quest to increase overall survival of patients suffering from the disease.

PARP inhibitors as precision medicine for cancer treatment

Personalized or precision medicine is an emerging treatment approach tailored to individuals or certain groups of patients based on their unique characteristics. These types of therapies guided by biomarkers tend to be more effective than traditional approaches, especially in cancer. The inhibitor against poly (ADP-ribose) polymerase (PARP), olaparib (Lynparza, AstraZeneca), which was approved by the US Food and Drug Administration (FDA) in 2014, demonstrated efficacy specifically for ovarian cancer patients harboring mutations in BRCA genes, which encode proteins in DNA double-strand break repairs. However, the response to PARP inhibitors has been less encouraging in other cancer types that also carry defects in the BRCA genes. Thus, furthering our understanding of the underlying mechanism of PARP inhibitors and resistance is critical to improve their efficacy. In this review, we summarize the results of preclinical studies and the clinical application of PARP inhibitors, and discuss the future direction of PARP inhibitors as a potential marker-guided personalized medicine for cancer treatment.

Triple-negative breast cancer: New therapeutic options via signalling transduction cascades

Triple-negative breast cancer is a highly aggressive type of mammalian carcinoma. It is defined by a rather weak expression of estrogen-, progesterone- and Her2-receptor, and is thus difficult to treat, resulting in low disease-free and overall survival rates of the affected patients. Hence it is important to find new therapeutic options. To this aim we analysed the incidence of some molecules from different signal transduction cascades by immunohistochemistry, which are known to correlate with triple-negative breast cancer, and correlated the expression of these molecules to different tumour traits, such as size, grading, menopausal stage, histology, lymph node affection, remote metastasis formation, and to the incidence of local and lymph node recurrence and metastasis by statistical analysis. Statistically significant correlations were found for a number of tumour characteristics and signalling molecules: HIF1α is correlated to tumour grading, β-catenin to the menopausal state of the patient, and for Notch1 a relation to lymph node affection is seen. In terms of different recurrences, a correlation of β-catenin to metastasis formation and lymph node affection could be shown, as well as coherences between XBP1 and lymph node recurrence, Notch1 and metastasis formation and FOXP3 and the occurrence of local recurrence. The presented results are in accordance with formerly published studies and therefore might comprise opportunities to develop new therapeutical strategies, which could help to handle this aggressive form of breast cancer in a manner, by which side effects would be reduced and therapeutical efficiency is increased.

Development of PARP inhibitors in gynecological malignancies

PARP inhibitors demonstrate synthetic lethality in tumors with BRCA1/2 mutations and other homologous recombination repair deficiencies by interfering with DNA repair and causing direct toxicity to DNA through PARP trapping. PARP inhibitors have been shown to be beneficial in the treatment of BRCA1/2-mutated ovarian cancers, which has led to a shift in the treatment paradigm of this disease. Further studies to establish the role of PARP inhibitors during earlier stages of treatment are ongoing. The use of PARP inhibitors in other cancers with homologous recombination repair deficiencies, such as breast cancer and prostate cancer, is gradually evolving as well, including their use in the neoadjuvant and adjuvant settings. PARP inhibitor combination strategies with chemotherapy, targeted agents, radiotherapy, and immunotherapy are also being explored. The role of predictive biomarkers, including molecular signatures and homologous recombination deficiency scores based on loss of heterozygosity and other structural genomic aberrations, will be crucial to improved patient stratification to enhance the clinical utility of PARP inhibitors. This may also allow the use of PARP inhibitors to be extended beyond tumors with specific homologous recombination DNA repair gene mutations in the future. An improved understanding of the mechanisms underlying PARP inhibitor resistance will also be important to enable the development of new approaches to increase efficacy. This is a field rich in opportunity, and the coming years should see a better understanding of which patients we should be treating with PARP inhibitors and where these agents should come in over the course of treatment.

Intrinsic Subtypes and Gene Expression Profiles in Primary and Metastatic Breast Cancer

Biological changes that occur during metastatic progression of breast cancer are still incompletely characterized. In this study, we compared intrinsic molecular subtypes and gene expression in 123 paired primary and metastatic tissues from breast cancer patients. Intrinsic subtype was identified using a PAM50 classifier and χ² tests determined the differences in variable distribution. The rate of subtype conversion was 0% in basal-like tumors, 23.1% in HER2-enriched (HER2-E) tumors, 30.0% in luminal B tumors, and 55.3% in luminal A tumors. In 40.2% of cases, luminal A tumors converted to luminal B tumors, whereas in 14.3% of cases luminal A and B tumors converted to HER2-E tumors. We identified 47 genes that were expressed differentially in metastatic versus primary disease. Metastatic tumors were enriched for proliferation-related and migration-related genes and diminished for luminal-related genes. Expression of proliferation-related genes were better at predicting overall survival in metastatic disease (OSmet) when analyzed in metastatic tissue rather than primary tissue. In contrast, a basal-like gene expression signature was better at predicting OSmet in primary disease compared with metastatic tissue. We observed correlations between time to tumor relapse and the magnitude of changes of proliferation, luminal B, or HER2-E signatures in metastatic versus primary disease. Although the intrinsic subtype was largely maintained during metastatic progression, luminal/HER2-negative tumors acquired a luminal B or HER2-E profile during metastatic progression, likely reflecting tumor evolution or acquisition of estrogen independence. Overall, our analysis revealed the value of stratifying gene expression by both cancer subtype and tissue type, providing clinicians more refined tools to evaluate prognosis and treatment. Cancer Res; 77(9); 2213-21. ©2017 AACR.

Prognostic and clinicopathological value of poly (adenosine diphosphate-ribose) polymerase expression in breast cancer: A meta-analysis

Background

Previous studies have shown that the poly (adenosine diphosphate-ribose) polymerase (PARP) level is a promising indicator of breast cancer. However, its prognostic value remains controversial. The present meta-analysis evaluated the prognostic value of PARP expression in breast cancer.

Materials and methods

Eligible studies were retrieved from the PubMed, Web of Science, Embase, and Cochrane Library databases through July 20, 2016. Studies investigating PARP expression as well as reporting survival data in breast cancer were included. Two independent reviewers carried out all literature searches. The pooled relative risk (RR) and hazard ratio (HR) with 95% confidence interval (95% CI) were applied to assess the association between PARP expression and the clinicopathological features and survival outcome in breast cancer.

Results

A total of 3506 patients from eight eligible studies were included. We found that higher PARP expression indicated a worse clinical outcome in early stage breast cancer, with a HR of 3.08 (95% CI, 1.14–8.29, P = 0.03) for disease-free survival and a HR of 1.82 (95% CI, 1.20–2.76; P = 0.005) for overall survival. Moreover, increased PARP expression was significantly associated with higher nuclear grade (RR, 1.51; 95% CI, 1.12–2.04; P = 0.008) in breast cancer. A similar correlation was detected in triple-negative breast cancer (TNBC; RR, 1.81; 95% CI, 1.04–3.17; P = 0.04).

Conclusions

Our findings indicated that elevated PARP expression correlated with worse prognosis in early stage breast cancer. Furthermore, high PARP expression was associated with higher nuclear grade and TNBC.

Up-Regulation of RFC3 Promotes Triple Negative Breast Cancer Metastasis and is Associated With Poor Prognosis Via EMT

Triple-negative breast cancer (TNBC) was regarded as the most aggressive and mortal subtype of breast cancer (BC) since the molecular subtype system has been established. Abundant studies have revealed that epithelial-mesenchymal transition (EMT) played a pivotal role during breast cancer metastasis and progression, especially in TNBC. Herein, we showed that inhibition the expression of replication factor C subunit 3 (RFC3) significantly attenuated TNBC metastasis and progression, which was associated with EMT signal pathway. In TNBC cells, knockdown of RFC3 can down-regulate mesenchymal markers and up-regulate epithelial markers, significantly attenuated cell proliferation, migration and invasion. Additionally, silencing RFC3 expression can decrease nude mice tumor volume, weight and relieve lung metastasis in vivo. Furthermore, we also demonstrated that overexpression of RFC3 in TNBC showed increased metastasis, progression and poor prognosis. We confirmed all of these results by immunohistochemistry analysis in 127 human TNBC tissues and found that RFC3 expression was significantly associated with poor prognosis in TNBC. Taken all these findings into consideration, we can conclude that up-regulation of RFC3 promotes TNBC progression through EMT signal pathway. Therefore, RFC3 could be an independent prognostic factor and therapeutic target for TNBC.

Effective personalized therapy for breast cancer based on predictions of cell signaling pathway activation from gene expression analysis

Current therapeutic outcomes for breast cancer underscore the complexity of treating a heterogeneous disease. Indeed, studies have shown that differences in gene expression among patients with the same subtype of breast cancer are correlated with the response to treatment. This strongly suggests that there is an urgent need to treat breast cancer with a personalized approach. Here we employed cell signaling pathway signatures to predict pathway activity in subtypes of MMTV-Myc mammary tumors. We then split tumors into subsets and developed individualized combinatorial treatments for two subtypes with distinct pathway activation patterns. Elevation of the EGFR, RAS and TGFβ pathways was observed in one subtype whereas these pathways were not predicted to be active in the other subtype that had high predicted activity of the Myc, Stat3 and Akt pathways. In a proof-of-principle experiment, treatment of these two subtypes with targeted therapies inhibited tumor growth only in the subtype of tumor where the therapy was designed to be active. We then analyzed gene expression profiles of human breast cancer patients and patient-derived xenograft (PDX) samples to predict pathway activity, and validated our approach of developing individualized treatments in mice with PDX tumors. Importantly, our combinatorial therapy resulted in tumor regression, including regression in PDX samples from triple-negative breast cancer. Together our data is a proof-of-principle experiment that demonstrates that cell signaling pathway signature-guided treatment for breast cancer is viable.

STAT3/NF-κB-Regulated Lentiviral TK/GCV Suicide Gene Therapy for Cisplatin-Resistant Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) represents approximately 20% of all breast cancers and appears resistance to conventional cytotoxic chemotherapy, demonstrating a particularly poor prognosis and a significantly worse clinical outcome than other types of cancer. Suicide gene therapy has been used for the in vivo treatment of various solid tumors in recent clinical trials. In tumor microenvironment, STAT3/NF-κB pathways are constitutively activated in stromal cells as well as in cancer stem cells (CSCs). In this study, we have cloned a novel STAT3/NF-κB-based reporter system to drive the expression of herpes simplex virus thymidine kinase (HSV-TK) against breast cancer. Lentiviral vector expressing HSV-TK under the regulation of STAT3/NF-κB fused response element was developed. In this setting, we exploited the constitutive STAT3/NF-κB activation in tumors to achieve higher transgene expression than that driven by a constitutively active CMV promotor in vivo. An orthotropic MDA-MB-231 triple negative breast cancer mouse model was used for evaluating the feasibility of STAT3-NF-κB-TK/GCV suicide gene therapy system.

The basal promoter activity of Lenti-CMV-TK and Lenti-STAT3-NF-κB-TK in MDA-MB-231 cells was compared by ³H-FEAU uptake assay. The Lenti-CMV-TK showed ~5 fold higher ³H-FEAU uptake then Lenti -STAT3-NF-κB-TK. In clonogenic assay, cells expressing Lenti-CMV-TK were 2-fold more sensitive to GCV than Lenti-STAT3-NF-κB-TK transduced cells. In vitro effect of STAT3-NF-κB-induced transgene expression was determined by 10ng/mL TNF-α induction and confirmed by western blot analysis and DsRedm fluorescent microscopy. In vivo evaluation of therapeutic effect by bioluminescence and [¹⁸F]FHBG microPET imaging indicated that Lenti-STAT3-NF-κB-TK showed more tumor growth retardation than Lenti-CMV-TK when GCV (20 mg/kg) was administered. The invasiveness and expression of cancer stem cell markers were both decreased after STAT3/NF-κB-regulated HSV-TK/GCV therapy. Moreover, STAT3/NF-κB signaling targeting could further sensitize tumor cells to cisplatin. This study successfully established a theranositic approach to treat triple-negative breast cancer via STAT3-NF-κB responsive element-driven suicide gene therapy. This platform may also be an alternative strategy to handle with drug-resistant cancer cells.

Predicting and Overcoming Chemotherapeutic Resistance in Breast Cancer

Our understanding of breast cancer and its therapeutic approach has improved greatly due to the advancement of molecular biology in recent years. Clinically, breast cancers are characterized into three basic types based on their immunohistochemical properties. They are triple-negative breast cancer, estrogen receptor (ER) and progesterone receptor (PR)-positive-HR positive breast cancer, and human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Even though these subtypes have been characterized, assessment of a breast cancer's receptor status is still widely used to determine whether or not a targeted therapy could be applied. Moreover, drug resistance is common in all breast cancer types despite the different treatment modalities applied. The development of resistance to different therapeutics is not mutually exclusive. It seems that tumor could be resistant to multiple treatment strategies, such as being both chemoresistant and monoclonal antibody resistant. However, the underlying mechanisms are complicated and need further investigation. In this chapter, we aim to provide a brief review of the different types of breast cancer and their respective treatment strategies. We also review the possible mechanisms of potential drug resistance associated with each treatment type. We believe that a better understanding of the drug resistance mechanisms can lead to a more effective and efficient therapeutic success.

Effectiveness and safety of poly (ADP-ribose) polymerase inhibitors in cancer therapy: A systematic review and meta-analysis

Poly (ADP-ribose) polymerase (PARP) inhibitors are a class of small-molecule drugs suppressing PARP enzymes activity, inducing the death of cells deficient in homologous recombination repair (HRR). HRR deficiency is common in tumor cells with BRCA gene mutation. Since their first clinical trial in 2003, PARP inhibitors have shown benefit in the treatment of HRR-deficient tumors. Recently, several randomized clinical trials (RCTs) have been conducted to investigate the potential benefit of administration of PARP inhibitors in cancer patients. However, the results remain controversial. To evaluate the efficiency and safety of PARP inhibitors in patients with cancer, we performed a comprehensive meta-analysis of RCTs. According to our study, PARP inhibitors could clearly improve progression-free survival (PFS), especially in patients with BRCA mutation. However, our study showed no significant difference in overall survival (OS) between the PARP inhibitors and controls, even in the BRCA mutation group. Little toxicity was reported in the rate of treatment correlated adverse events (AEs) in PARP inhibitor group compared with controls. In conclusion, PARP inhibitors do well in improving PFS with little toxicity, especially in patients with BRCA deficiency.

The Correlation Between PARP1 and BRCA1 in AR Positive Triple-negative Breast Cancer

Triple-negative breast cancer (TNBC) lacks estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER-2) expression and thus cannot benefit from conventional hormonal or anti-HER2 targeted therapies. Anti-androgen therapy has shown a certain effect on androgen receptor (AR) positive TNBC. The emerging researches have proved that poly (ADP-ribose) polymerase (PARP) inhibitor is effective in BRCA1-deficient breast cancers. We demonstrated that combination of AR antagonist (bicalutamide) and PARP inhibitor (ABT-888) could inhibit cell viability and induce cell apoptosis significantly whatever in vitro or in vivo setting in AR-positive TNBC. Previous studies have proved that both BRCA1 and PARP1 have close connections with AR in prostate cancer. We explored the correlation among AR, PARP1 and BRCA1 in TNBC for the first time. After BRCA1 overexpression, the expression of AR and PARP1 were decreased in mRNA and protein levels. Additionally, AR positively regulated PARP1 while PARP1 also up-regulated AR expression in vitro. We also confirmed BRCA1 expression was negatively correlated with AR and PARP1 in TNBC patients using a tissue microarray with TNBC patient samples. These results suggest that the combination of bicalutamide and PARP inhibitor may be a potential strategy for TNBC patients and merits further evaluation.

Use of poly ADP-ribose polymerase [PARP] inhibitors in cancer cells bearing DDR defects: the rationale for their inclusion in the clinic

BACKGROUND

DNA damage response (DDR) defects imply genomic instability and favor tumor progression but make the cells vulnerable to the pharmacological inhibition of the DNA repairing enzymes. Targeting cellular proteins like PARPs, which cooperate and complement molecular defects of the DDR process, induces a specific lethality in DDR defective cancer cells and represents an anti-cancer strategy. Normal cells can tolerate the DNA damage generated by PARP inhibition because of an efficient homologous recombination mechanism (HR); in contrast, cancer cells with a deficient HR are unable to manage the DSBs and appear especially sensitive to the PARP inhibitors (PARPi) effects.

MAIN BODY

In this review we discuss the proof of concept for the use of PARPi in different cancer types and the success and failure of their inclusion in clinical trials. The PARP inhibitor Olaparib [AZD2281] has been approved by the FDA for use in pretreated ovarian cancer patients with defective BRCA1/2 genes, and by the EMEA for maintenance therapy in platinum sensitive ovarian cancer patients with defective BRCA1/2 genes. BRCA mutations are now recognised as the molecular targets for PARPi sensitivity in several tumors. However, it is noteworthy that the use of PARPi has shown its efficacy also in non-BRCA related tumors. Several trials are ongoing to test different PARPi in different cancer types. Here we review the concept of BRCAness and the functional loss of proteins involved in DDR/HR mechanisms in cancer, including additional molecules that can influence the cancer cells sensitivity to PARPi. Given the complexity of the existing crosstalk between different DNA repair pathways, it is likely that a single biomarker may not be sufficient to predict the benefit of PARP inhibitors therapies. Novel general assays able to predict the DDR/HR proficiency in cancer cells and the PARPi sensitivity represent a challenge for a personalized therapy.

CONCLUSIONS

PARP inhibition is a potentially important strategy for managing a significant subset of tumors. The discovery of both germline and somatic DNA repair deficiencies in different cancer patients, together with the development of new PARP inhibitors that can kill selectively cancer cells is a potent example of targeting therapy to molecularly defined tumor subtypes.

Factors associated with failure of oncology drugs in late-stage clinical development: A systematic review

BACKGROUND

We aimed to describe the reasons for failure of experimental anticancer drugs in late-stage clinical development.

MATERIAL AND METHODS

We searched the PharmaProjects database (https://citeline.com/products/pharmaprojects/) for anticancer drugs discontinued between 01/01/2009 and 06/30/2014. Drug programs that reached phase III trials, but never gained Food and Drug Administration (FDA) approval were compared to 37 anti-cancer drugs achieving FDA approval in this time period.

RESULTS

Forty-two drugs fit our criteria for development failures. These failed drugs (49% targeted, 23% cytotoxics, and 28% other) were tested in 43 cancer indications (drug programs). Only 16% (7/43) of failed drug programs adopted a biomarker-driven rationale for patient selection versus 57% (21/37) of successful drug programs (P<0.001). Phase II trial information was available in 32 of 43 failed drug programs and in 32 of 37 successful programs. Nine of the 32 trials (28%) of failed drugs versus 28 of 32 trials (87%) of successful drugs (P<0.001) achieved proof of concept (single agent response rate (RR) ⩾20% or combination therapy showing a ⩾20% RR increase above the median historical RR without the experimental agent (with a minimal absolute increase of 5%) or a randomized phase II trial showing significance (P⩽0.05) for its primary outcome). No pattern of study sites, trial design or funding characteristics emerged from the failed drug analysis.

CONCLUSION

For drugs that reached Phase III, lack of a biomarker-driven strategy and failure to attain proof of concept in phase II are potential risk factors for later discontinuation, especially for targeted agents.

Novel therapeutic strategies for patients with triple-negative breast cancer

Triple-negative breast cancer (TNBC) represents a very heterogeneous group of breast diseases. Currently, the backbone of therapy for TNBC is mainly chemotherapy as there are no effective specific targeted agents approved to treat TNBC. Despite initial responses to chemotherapy, resistance frequently and rapidly develops and metastatic TNBC has a poor prognosis. Therefore, new targeted strategies are, accordingly, urgently needed. This article discusses the recent developments in targeted agents explored for TNBC, aiming to offer novel therapeutic strategies that can potentially assist in designing personalized therapeutics in the future as well as provide the basis for further research in an attempt to target TNBC.

High PARP-1 expression is associated with tumor invasion and poor prognosis in gastric cancer

Poly (adenosine diphosphate-ribose) polymerase 1 (PARP-1) was previously demonstrated to be overexpressed in numerous malignant tumors and associated with invasiveness and poor prognosis. However, the expression of the PARP-1 protein in gastric cancer and its association with clinical outcomes requires further investigation. In the present study, the expression of PARP-1 in 564 gastric cancer tissues and 335 tumor-adjacent control tissues is investigated, using tissue microarray-based immunohistochemistry. PARP-1 expression levels were demonstrated to be significantly higher in gastric cancer tissue samples, as compared with control tissue samples. In gastric cancer, high PARP-1 expression levels were significantly associated with Helicobacter pylori (H. pylori) infection (P=0.032), decreased differentiation (P<0.001), increased depth of invasion (P=0.037), presence of lymphatic invasion (P<0.001), presence of lymph node metastasis (P<0.001), and advanced tumor-node-metastasis (TNM) stage (P=0.015). High PARP-1 expression levels were associated with a significantly shorter overall survival rate (P<0.001) and disease-free survival rate (P=0.001) in patients with gastric cancer, particularly a subset of patients with H. pylori infection or an advanced TNM stage. In addition, univariate analysis indicated that PARP-1 high expression levels were significantly associated with a poor prognosis in gastric cancer. These results suggest that PARP-1 expression may be involved in the progression and prognosis of gastric cancer, particularly H. pylori-positive or advanced-stage gastric cancer.

Individual and Combined Expression of DNA Damage Response Molecules PARP1, γH2AX, BRCA1, and BRCA2 Predict Shorter Survival of Soft Tissue Sarcoma Patients

DNA damage response (DDR) molecules are protective against genotoxic stresses. DDR molecules are also involved in the survival of cancer cells in patients undergoing anti-cancer therapies. Therefore, DDR molecules are potential markers of cancer progression in addition to being potential therapeutic targets. In this study, we evaluated the immunohistochemical expression of PARP1, γH2AX, BRCA1, and BRCA2 and their prognostic significance in 112 cases of soft tissue sarcoma (STS). The expression of PARP1, γH2AX, BRCA1, and BRCA2 were significantly associated with each other and were associated with higher tumor stage and presence of distant metastasis. The expression of PARP1, γH2AX, and BRCA2 were significantly associated with shorter disease-specific survival (DSS) and event-free survival (EFS) by univariate analysis. BRCA1 expression was associated with shorter DSS. Multivariate analysis revealed the expression of PARP1 and γH2AX to be independent indicators of poor prognosis of DSS and EFS. BRCA2 expression was an independent indicator of poor prognosis of DSS. In addition, the combined expressional patterns of PARP1, γH2AX, BRCA1, and BRCA2 (CSddrm) were independent prognostic predictors of DSS (P < 0.001) and EFS (P = 0.016). The ten-year DSS rate of the CSddrm-low, CSddrm-intermediate, and CSddrm-high subgroups were 81%, 26%, and 0%, respectively. In conclusion, this study demonstrates that the individual and combined expression patterns of the DDR molecules PARP1, γH2AX, BRCA1, and BRCA2 could be predictive of the prognosis of STS patients and suggests that controlling the activity of these DDR molecules could be employed in new therapeutic stratagems for the treatment of STS.

Update on Poly-ADP-ribose polymerase inhibition for ovarian cancer treatment

BACKGROUND

Despite standard treatment for epithelial ovarian cancer (EOC), that involves cytoreductive surgery followed by platinum-based chemotherapy, and initial high response rates to these, up to 80 % of patients experience relapses with a median progression-free survival of 12-18 months. There remains an urgent need for novel targeted therapies to improve clinical outcomes in ovarian cancer. Of the many targeted therapies currently under evaluation, the most promising strategies developed thus far are antiangiogenic agents and Poly(ADP-ribose) polymerase (PARP) inhibitors. Particularly, PARP inhibitors are active in cells that have impaired repair of DNA by the homologous recombination (HR) pathway. Cells with mutated breast related cancer antigens (BRCA) function have HR deficiency, which is also present in a significant proportion of non-BRCA-mutated ovarian cancer ("BRCAness" ovarian cancer). The prevalence of germline BRCA mutations in EOC has historically been estimated to be around 10-15 %. However, recent reports suggest that this may be a gross underestimate, especially in women with high-grade serous ovarian cancer (HGSOC). The emergence of the DNA repair pathway as a rational target in various cancers led to the development of the PARP inhibitors. The concept of tumor-selective synthetic lethality heralded the beginning of an eventful decade, culminating in the approval by regulatory authorities both in Europe as a maintenance therapy and in the United States treatment for advanced recurrent disease of the first oral PARP inhibitor, olaparib, for the treatment of BRCA-mutated ovarian cancer patients. Other PARP inhibitors are clearly effective in this disease and, within the next years, the results of ongoing randomized trials will clarify their respective roles.

CONCLUSION

This review will discuss the different PARP inhibitors in development and the potential use of this class of agents in the future. Moreover, combination strategies involving PARP inhibitors are likely to receive increasing attention. The utility of PARP inhibitors combined with cytotoxic chemotherapy is of doubtful value, because of enhanced toxicity of this combination; while, more promising strategies include the combination with antiangiogenic agents, or with inhibitors of the P13K/AKT pathway and new generation of immunotherapy.

Breast Cancer: A Molecular and Redox Snapshot

SIGNIFICANCE

Breast cancer is a unique disease characterized by heterogeneous cell populations causing roadblocks in therapeutic medicine, owing to its complex etiology and primeval understanding of the biology behind its genesis, progression, and sustenance. Globocan statistics indicate over 1.7 million new breast cancer diagnoses in 2012, accounting for 25% of all cancer morbidities.

RECENT ADVANCES

Despite these dismal statistics, the introduction of molecular gene signature platforms, progressive therapeutic approaches in diagnosis, and management of breast cancer has led to more effective treatment strategies and control measures concurrent with an equally reassuring decline in the mortality rate.

CRITICAL ISSUES

However, an enormous body of research in this area is requisite as high mortality associated with metastatic and/or drug refractory tumors continues to present a therapeutic challenge. Despite advances in systemic chemotherapy, the median survival of patients harboring metastatic breast cancers continues to be below 2 years.

FUTURE DIRECTIONS

Hence, a massive effort to scrutinize and evaluate chemotherapeutics on the basis of the molecular classification of these cancers is undertaken with the objective to devise more attractive and feasible approaches to treat breast cancers and improve patients' quality of life. This review aims to summarize the current understanding of the biology of breast cancer as well as challenges faced in combating breast cancer, with special emphasis on the current battery of treatment strategies. We will also try and gain perspective from recent encounters on novel findings responsible for the progression and metastatic transformation of breast cancer cells in an endeavor to develop more targeted treatment options. Antioxid. Redox Signal. 25, 337-370.

Salivary duct carcinomas can be classified into luminal androgen receptor-positive, HER2 and basal-like phenotypes

AIMS

The aim of this study was to devise a molecular classification for salivary duct carcinomas (SDCs) based on the similarities between SDCs and breast carcinomas and on characteristics of the microarray-based gene expression profiling-defined molecular subtypes of breast cancer.

METHODS AND RESULTS

Forty-two pure salivary duct carcinomas, 35 of which contained an in-situ component as defined by histological review and/or immunohistochemical analysis, were stained with antibodies for oestrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR), human epidermal growth factor receptor 2 (HER2), epidermal growth factor receptor (EGFR) and cytokeratin (CK) 5/6. Based on these markers, tumours were classified into HER2, luminal androgen receptor-positive, basal-like, luminal and indeterminate phenotype. Analysis revealed that 16.7%, 69%, 4.8%, 9.5% and 0% were of HER2, luminal androgen receptor-positive, basal-like, indeterminate and luminal phenotype, respectively. The in-situ and invasive components displayed the same molecular subtype in all but one case.

CONCLUSION

Salivary duct carcinomas can be classified into molecular subgroups approximately equivalent to those in the breast. We also report on the existence of a subgroup of bona fide pure salivary duct carcinomas that have a 'basal-like' phenotype. Understanding the phenotypic complexity of SDCs may help to expedite the identification of novel therapeutic targets for these aggressive tumours.

Differential Potential of Pharmacological PARP Inhibitors for Inhibiting Cell Proliferation and Inducing Apoptosis in Human Breast Cancer Cells

BRCA1/2-mutant cells are hypersensitive to inactivation of poly(ADP-ribose) polymerase 1 (PARP-1). We recently showed that inhibition of PARP-1 by NU1025 is strongly cytotoxic for BRCA1-positive BT-20 cells, but not BRCA1-deficient SKBr-3 cells. These results raised the possibility that other PARP-1 inhibitors, particularly those tested in clinical trials, may be more efficacious against BRCA1-deficient SKBr-3 breast cancer cells than NU1025. Thus, in the presented study the cytotoxicity of four PARP inhibitors under clinical evaluation (olaparib, rucaparib, iniparib and AZD2461) was examined and compared to that of NU1025. The sensitivity of breast cancer cells to the PARP-1 inhibition strongly varied. Remarkably, BRCA-1-deficient SKBr-3 cells were almost completely insensitive to NU1025, olaparib and rucaparib, whereas BRCA1-expressing BT-20 cells were strongly affected by NU1025 even at low doses. In contrast, iniparib and AZD2461 were cytotoxic for both BT-20 and SKBr-3 cells. Of the four tested PARP-1 inhibitors only AZD2461 strongly affected cell cycle progression. Interestingly, the anti-proliferative and pro-apoptotic potential of the tested PARP-1 inhibitors clearly correlated with their capacity to damage DNA. Further analyses revealed that proteomic signatures of the two studied breast cancer cell lines strongly differ, and a set of 197 proteins was differentially expressed in NU1025-treated BT-20 cancer cells. These results indicate that BT-20 cells may harbor an unknown defect in DNA repair pathway(s) rendering them sensitive to PARP-1 inhibition. They also imply that therapeutic applicability of PARP-1 inhibitors is not limited to BRCA mutation carriers but can be extended to patients harboring deficiencies in other components of the pathway(s).

Genomic instability in pancreatic adenocarcinoma: a new step towards precision medicine and novel therapeutic approaches

Pancreatic cancer is one of the most challenging cancers. Whole genome sequencing studies have been conducted to elucidate the underlying fundamentals underscoring disease behavior. Studies have identified a subgroup of pancreatic cancer patients with distinct molecular and clinical features. Genetic fingerprinting of these tumors is consistent with an unstable genome and defective DNA repair pathways, which creates unique susceptibility to agents inducing DNA damage. BRCA1/2 mutations, both germline and somatic, which lead to impaired DNA repair, are found to be important biomarkers of genomic instability as well as of response to DNA damaging agents. Recent studies have elucidated that PARP inhibitors and platinum agents may be effective to induce tumor regression in solid tumors bearing an unstable genome including pancreatic cancer. In this review we discuss the characteristics of genomic instability in pancreatic cancer along with its clinical implications and the utility of DNA targeting agents particularly PARP inhibitors as a novel treatment approach.

Advancing Clinical Trials to Streamline Drug Development

The last decade in oncology has been marked by the identification of numerous new potential cancer targets and even more agents designed to inhibit them. The matrix of new targets, new agents, and the companion diagnostics required to identify the right patient for the right drug has created a major challenge for the clinical trial process. This has been compounded by the addition of new immunomodulators targeting the host immune system rather than the tumor. Recognizing the need for new approaches, industry, investigators, and regulators have responded to this challenge. New clinical trial designs are being evaluated to incorporate the genomic sequence data being obtained almost routinely after cancer diagnosis. New dose-finding approaches are being proposed to identify the maximum effective dose rather than the maximum tolerated dose. The FDA is involved in the drug approval process from points early in development and has accepted registration quality data from expansion cohorts in support of drug approval. Despite progress on several fronts, many challenges remain, including the lack of predictability of preclinical data for clinical results and phase II data for phase III results, an infrastructure that can be an obstacle to clinical trial development and implementation, and the increasing use of contracted clinical research organizations that limit a fit-for-purpose approach to clinical trial execution. Perhaps most challenging and important of all are the difficulties with clinical trial accrual that can prevent study completion. Both the innovations and the challenges highlight the important role of process in progress in clinical oncology.

Failures in Phase III: Causes and Consequences

Phase III randomized controlled trials (RCT) in oncology fail to lead to registration of new therapies more often than RCTs in other medical disciplines. Most RCTs are sponsored by the pharmaceutical industry, which reflects industry's increasing responsibility in cancer drug development. Many preclinical models are unreliable for evaluation of new anticancer agents, and stronger evidence of biologic effect should be required before a new agent enters the clinical development pathway. Whenever possible, early-phase clinical trials should include pharmacodynamic studies to demonstrate that new agents inhibit their molecular targets and demonstrate substantial antitumor activity at tolerated doses in an enriched population of patients. Here, we review recent RCTs and found that these conditions were not met for most of the targeted anticancer agents, which failed in recent RCTs. Many recent phase III RCTs were initiated without sufficient evidence of activity from early-phase clinical trials. Because patients treated within such trials can be harmed, they should not be undertaken. The bar should also be raised when making decisions to proceed from phase II to III and from phase III to marketing approval. Many approved agents showed only better progression-free survival than standard treatment in phase III trials and were not shown to improve survival or its quality. Introduction of value-based pricing of new anticancer agents would dissuade the continued development of agents with borderline activity in early-phase clinical trials. When collaborating with industry, oncologists should be more critical and better advocates for cancer patients.

[Non-metastatic triple-negative breast cancer in 2016: Definitions and management]

Triple-negative breast cancer (TN), as defined by the triple negativity in immunohistochemistry: the absence of estrogen receptor, progesterone receptor and the absence of overexpression or amplification of HER2, corresponds to 15 % of invasive breast cancers. This is a very heterogeneous group of tumors both at the genomic and transcriptomic level and at morphological, clinical and prognostic level. Although there are some good prognosis forms, the majority of TN tumors is characterized by a poor prognosis with a greater frequency of visceral metastases and a maximum risk of relapse in the first two years after diagnosis. Systemic adjuvant treatment with chemotherapy is almost always indicated. The surgical treatment and radiotherapy treatment should be comparable to the other subtypes and obey the same rules of oncologic surgery. TN tumors are not associated with a higher risk of locoregional relapse after conservative treatment and adjuvant radiotherapy. Optimization of systemic therapies is currently and for the last decade a challenge. A number of targeted therapies and efficiency biomarkers identification of these targeted therapies is essential to allow significant progress in optimizing systemic therapy for these tumors.

An Update on Poly(ADP-ribose)polymerase-1 (PARP-1) Inhibitors: Opportunities and Challenges in Cancer Therapy

Poly(ADP-ribose)polymerase-1 (PARP-1) is a critical DNA repair enzyme in the base excision repair pathway. Inhibitors of this enzyme comprise a new type of anticancer drug that selectively kills cancer cells by targeting homologous recombination repair defects. Since 2010, important advances have been achieved in PARP-1 inhibitors. Specifically, the approval of olaparib in 2014 for the treatment of ovarian cancer with BRCA mutations validated PARP-1 as an anticancer target and established its clinical importance in cancer therapy. Here, we provide an update on PARP-1 inhibitors, focusing on breakthroughs in their clinical applications and investigations into relevant mechanisms of action, biomarkers, and drug resistance. We also provide an update on the design strategies and the structural types of PARP-1 inhibitors. Opportunities and challenges in PARP-1 inhibitors for cancer therapy will be discussed based on the above advances.