Triple-negativebreastcancer (TNBC) is a heterogeneous disease in which the tumors do not express estrogen receptor (ER), progesterone receptor (PgR) or human epidermal growth factor receptor 2 (HER2). Classical receptor-targeted therapies such as tamoxifen or trastuzumab are therefore unsuitable and combinations of surgery, chemotherapy and/or radiotherapy are required. Photoimmunotheranostics is a minimally invasive approach in which antibodies deliver nontoxic photosensitizers that emit light to facilitate diagnosis and produce cytotoxic reactive oxygen species to induce apoptosis and/or necrosis in cancer cells. We developed a panel of photoimmunotheranostic agents against three TNBC-associated cell surface antigens. Antibodies against epidermal growth factor receptor (EGFR), epithelial cell adhesion molecule (EpCAM) and chondroitin sulfate proteoglycan 4 (CSPG4) were conjugated to the highly potent near-infrared imaging agent/photosensitizer IRDye ® 700DX phthalocyanine using SNAP-tag technology achieving clear imaging in both breastcancer cell lines and human biopsies and highly potent phototherapeutic activity with IC50 values of 62–165 nM against five different cell lines expressing different levels of EGFR, EpCAM and CSPG4. A combination of all three reagents increased the therapeutic activity against TNBC cells by up to 40%.
Triple-negativebreastcancer (TNBC) comprises a het- erogeneous group of diseases, defined by the absence of an estrogen receptor, progesterone receptor and HER2 expression. TNBC accounts for approximately 15% of breastcancer cases and is now the subtype with the worst prognosis and novel concepts are urgently needed. No targeted treatment beyond anti-VEGF therapy is ap- proved for TNBC so far and cytotoxic agents are the mainstay for the treatment of the advanced disease. Up to 20% of patients with TNBC harbor a germline BRCA mutation [ 3 ]. Recently, the results of the phase III trial OlympiAD comparing olaparib, an oral poly(ADP-ri- bose) polymerase (PARB) inhibitor with standard chemotherapy in pretreated metastatic breastcancer pa- tients harboring a germline BRCA mutation have been published showing favorable efficacy and safety results for the PARP inhibitor [ 4 ]. Therefore, an approved target treatment option for a subset of TNBC patients can be awaited within the next year. Due to a generally aggres- sive course of disease there is an urgent need for the in- vestigation of novel drugs and drug combinations.
Triplenegativebreastcancer (TNBC) was shown to have the poorest prognosis amongst BC subtypes. Not only because of the highest CNS involvement rate in BC subtypes of 18% but most of all due to the lack of effective systemic treatment strategies for the primary metastatic disease (14). Whilst hormone receptor positive tumors bear the option for endocrine therapy and HER2 positive tumors for HER-2 targeted therapy, TNBC is up to now a challenging condition in terms of treatment options. Moreover, it has been shown that brain metastases free survival (BMFS), classified as time from diagnosis of extracranial metastasis to diagnosis of BM was shortest in TNBC with 14 months, compared to HER2-positive tumors with 18 months and luminal tumors with 34 months, reflecting the aggressiveness of this specific BC subtype (15). Furthermore, survival analyses show that among BC patients with BM, the TNBC subtype has the shortest OS with 4.9 months whilst the longest OS with BM was demonstrated in the Luminal/HER2 positive subtype with 19 months (16).
Development of prostate-specific membrane antigen (PSMA) addressing small molecules initiated applica- tion of their radiolabeled derivatives for theranostics of prostate cancer (PrCa) [ 1 ]. Gene expression analysis revealed PSMA presence in several cancer types lead- ing to increasing acceptance of PSMA as a target for positron emission tomography/computer tomography (PET/CT) imaging in patients [ 2 ]. Due to the enzymatic ac- tivity and its role during neo-angiogenic processes, PSMA becomes an attractive target for numerous solid tumor en- tities including glioma, thyroid, bronchial, hepatocellular, ovarian, and breastcancer. Unlike in prostate cancer, PSMA expression is preferentially presented in endothelial cells of tumor-associated neo-vasculature, with no endothe- lial expression under physiological conditions [ 3 – 6 ]. Thus, addressing PSMA presents now one of the most specific and effective therapeutic approaches, especially for tumor entities lacking targetable cell surface markers. Among them, the triple-negativebreastcancer (TNBC) is standing out because of its extreme aggressive progression and the absence of druggable receptors like the estrogen and pro- gesterone receptors, and of the human epidermal growth factor receptor 2 (Her2). Moreover, TNBC occur frequently in younger women, many of them carrying BRCA-1 muta- tions. Due to the phenotype, the possibilities for treatment are limited, as endocrine therapy with tamoxifen or aromatase-inhibitors and anti-Her2 therapy with trastuzu- mab are ineffective. The low 5-year survival rate of 77% vs. 93% for non-TNBC visualizes the urgent need for the development of more efficient therapy options [ 7 ]. Many therapeutic concepts using, e.g., poly (ADP-ribose) poly- merase (PARP) inhibitors (iniparib, olaparib) or VEGF inhibitors (bevacizumab), have been developed for an im- proved treatment of the TNBC [ 8 – 10 ]. Even though these strategies did not yield an expected increase in cancer cell responsiveness, they proof the potential of targeting neo- angiogenesis and the potential activity of DNA damaging pharmaceuticals.
men with high-risk metastatic castration resistant PCA starting abiraterone acetate or enzalutamide treatment, the detection of AR-V7 in CTCs by two assays was independently associated with shorter PFS and OS, concluding that such men should be offered alternative treatments ( 54 ). Based on the findings in PCA that not the AR itself but AR-V7 has been linked to resistance toward anti-AR drugs and thus, therapeutic failure, we can only speculate that AR inhibitory treatment might not be successful in non-metastatic TNBC since in two thirds of our patients with AR+ CTCs, AR-V7 was also expressed. Nevertheless, although not analyzing CTCs, our findings are supported by Hickey et al., who showed that AR-V7 protein was highly expressed in tumor tissues of a subgroup of HR-negative BCs. Moreover, they observed enzalutamide to induce AR and also AR-V7 transcript expression in MDA-MB-453 cells and primary BCs. This group finally raised caution when exploring AR inhibitory treatment in women with BC and proposed the potential of AR- V7 as a predictive biomarker of anti-AR therapy response ( 38 ). We rarely found CTC-positive patients with regard to prostate cancer related genes after therapy. Thus, a decrease in CTC- positivity after therapy might also be explained by a reduction of CTC numbers under the given therapy. Due to the molecular approach used for this study, we cannot show CTC counts before and after therapy. However, we have already demonstrated that neoadjuvant therapy was able to eliminate most of the CTCs present before therapy in locally advanced BC. Interestingly, most of the residual CTCs after therapy displayed mesenchymal and/or stem cell like features ( 55 ).
reduced anti-cancer activity (121). However, several studies published by our group have previously shown that combining the anti-CD64 antibody fragment H22 with human enzymes including Granzyme B, MAP and angiogenin result in CFPs with comparable activities to ETA’-based IT (125, 149, 153, 155). In this study, in vitro cell viability assays demonstrated that the CFPs resulted in a 5-10 fold lower toxicity than their ETA’ counterparts in TNBC cell lines (Figure 10, Figure 30). The reduced toxicity could be attributed to the lack of translocation domains and endosomal escape mechanism. In order to facilitate and enhance endosomal escape, attempts to incorporate adapters into human CFPs design were done by our group as well as other groups (111, 274). These adapters facilitate endosomal escape, and have been shown to improve the translocation efficiency of the CFPs and increase their cytotoxicity. Such adapters can be inspired from the native translocation domains of bacterial and plant toxins, as well as the native signal peptides present in intracellular human proteins. Furthermore, Cao et al. (274) observed greater cytotoxicity when a pH-sensitive fusogenic peptide was incorporated into an anti HER2/ Granzyme B CFP. However, pH- sensitive adapter must be used with caution due to the possibility of reduced stability and the premature release of the toxins before reaching the target cells.
Pembrolizumab in triple-negativebreastcancer In early stage triple-negativebreastcancer (TNBC), neoadjuvant chemotherapy consisting of anthracy- clines, cyclophosphamide, taxanes and carboplatin is regarded as a potential treatment standard based upon results of the phase III BrighTNess trial, where the quadruple combination achieved pathologic com- plete response (pCR) rates in excess of 50% [ 1 ]. The KEYNOTE-522 study evaluated the potential role of adding pembrolizumab to this regimen [ 2 ]. A total of 1174 patients were randomized to receive four cycles of paclitaxel plus carboplatin followed by dox- orubicine/cyclophosphamide (AC) or epirubicine/ cyclophosphamide (EC) in combination with pem- brolizumab or placebo; placebo or immunotherapy were continued in the postneoadjvant part of the trial for another 27 weeks. Addition of pembrolizumab to neoadjuvant chemotherapy increased pCR rates from 51.2 to 64.8% (Δ13.6%; p = 0.00055). This effect was independent of PD-L1 expression as defined by CPS (combined positive score; 22C3 pharmDx assay). Patients with PD-L1 positive tumours had a higher pCR rate independent of treatment arm; of note, the additional benefit was most pronounced in patients with node-positive disease and those receiving weekly carboplatin as opposed to those receiving carboplatin once every three weeks. Event-free survival (EFS) was defined as co-primary endpoint; at the 18-month median follow-up, there was a nonsignificant 6% absolute difference in favour of the pembrolizumab group (EFS 91.3% vs. 85.3%; hazard ratio [HR] 0.63; 95% confidence interval [CI] 0.43–0.93). No new safety signals were observed. In summary, the pCR rate with quadruple chemotherapy combined with pembrolizumab is the highest reported in TNBC hith- erto; in addition, early EFS data are intriguing and the size of the EFS difference suggests a benefit of im-
Gerdes for the recruitment and genetic counseling of participants; Alicia Barroso, Rosario Alonso and Guillermo Pita; all the individuals and the researchers who took part in CONSIT TEAM (Consorzio Italiano Tumori Ereditari Alla Mammella), thanks in particular: Giulia Cagnoli, Roberta Villa, Irene Feroce, Mariarosaria Calvello, Riccardo Dolcetti, Giuseppe Giannini, Laura Papi, Gabriele Lorenzo Capone, Liliana Varesco, Viviana Gismondi, Maria Grazia Tibiletti, Daniela Furlan, Antonella Savarese, Aline Martayan, Stefania Tommasi, Brunella Pilato, Isabella Marchi, Elena Bandieri, Antonio Russo, Daniele Calistri and the personnel of the Cogentech Cancer Genetic Test Laboratory, Milan, Italy. FPGMX: members of the Cancer Genetics group (IDIS): Ana Blanco, Miguel Aguado, Uxía Esperón and Belinda Rodríguez. We thank all participants, clinicians, family doctors, researchers, and technicians for their contributions and commitment to the DKFZ study and the collaborating groups in Lahore, Pakistan (Noor Muhammad, Sidra Gull, Seerat Bajwa, Faiz Ali Khan, Humaira Naeemi, Saima Faisal, Asif Loya, Mohammed Aasim Yusuf) and Bogota, Colombia (Diana Torres, Ignacio Briceno, Fabian Gil). Genetic Modiﬁers of Cancer Risk in BRCA1/ 2 Mutation Carriers (GEMO) study is a study from the National Cancer Genetics Network UNICANCER Genetic Group, France. We wish to pay a tribute to Olga M. Sinilnikova, who with Dominique Stoppa-Lyonnet initiated and coordinated GEMO until she sadly passed away on the 30th June 2014. The team in Lyon (Olga Sinilnikova, Mélanie Léoné, Laure Barjhoux, Carole Verny-Pierre, Sylvie Mazoyer, Francesca Damiola, Valérie Sornin) managed the GEMO samples until the biological resource centre was transferred to Paris in December 2015 (Noura Mebirouk, Fabienne Lesueur, Dominique Stoppa-Lyonnet). We want to thank all the GEMO collaborating groups for their contribution to this study. Drs.Soﬁa Khan, Irja Erkkilä and Virpi Palola; The Hereditary Breast and Ovarian Cancer
In the neoadjuvant treatment of triple-negativebreastcancer (TNBC), the exact role of carboplatin is still debated; two important trials in this field were pre- sented at this year’s ASCO Annual Meeting. The phase III GeparOcto study [ 1 ] randomized 961 pa- tients (43% TNBC; 46% N+) to a GeparSixto [ 2 ] style regimen of weekly non-pegylated liposomal doxoru- bicin, paclitaxel and carboplatin (P[Cb]) or an intensi- fied dose-dense (idd) regimen of sequential epirubicin (150 mg/m 2 ), paclitaxel (225 mg/m 2 ) and cyclophos- phamide (2000 mg/m 2 ) each given for three cycles (EPC); trastuzumab plus pertuzumab were added in the HER2-positive population. Pathologic complete remission rates (pCR) were high and similar in be- tween both groups (PM[Cb] 47.6%; EPC 48.3%) in the entire population as well as in the subset of patients with TNBC (51.7% vs. 48.5%). On the other hand, a high rate of treatment discontinuations was seen in both arms with numbers favouring EPC (PM[Cb] 33.8%; EPC 16.4%); in addition, two toxicity-related deaths were recorded.
Summary While immunotherapy (IOT) with mono- clonal antibodies has long been present in HER2- positive breastcancer, the development of modern IOT concepts such as PD-1/PD-L1 targeting immune checkpoint inhibitors has been slow compared with other malignancies such a melanoma or lung can- cer. Recent clinical trials of IOT have focused on triple-negativebreastcancer (TNBC) as no specific treatment options beyond chemotherapy have been available in this subtype; in addition, TNBC appar- ently harbours the largest immunogenic potential. Meanwhile, initial results from the phase III IMpas- sion130 trial have been presented; here, the addition of atezolizumab to nab–paclitaxel led to a clinically meaningful prolongation of overall survival in the PD-L1 positive subset, potentially defining a novel standard-of-care in the first-line treatment of TNBC. Further evaluation of checkpoint inhibitors alone or in combination with chemotherapy or targeted drugs are currently ongoing in TNBC as well as in other breastcancer subtypes and clinical development is also ongoing in the adjuvant and neoadjuvant set- tings. This short review summarizes results of recent trials with a focus on clinical outcome data and dis- cusses the ongoing development of IOT in breastcancer.
About one third of patients with triple-negativebreastcancer (TNBC) treated with standard NACT achieve pCR. Preclinical trials stated TNBC to be more sensi- tive to interstrand crosslinking agents such as plat- inum salts due to deficiencies in the BRCA-associ- ated DNA repair mechanism . Especially in BRCA1- mutated patients treated with carboplatin as part of NACT, pCR rates of up to 75% could be reached . So far, five randomized phase II and one phase III trial addressed the use of carboplatin as part of NACT for patients with TNBC (Table 1):
Martin et al. [ 26 ] reported that miR-335 may also act in an oncogenic way in BC, to repress genes involved in the ERα signaling pathway, and consequently, to enhance re- sistance to the growth inhibitory effects of tamoxifen. Contrary to our findings that show significantly upregu- lated levels of exosomal miR-365 in the subgroup of HER2-positive (but not in TNBC), miR-365 was reported to be downregulated and act as a tumor suppressor in BC. Kodahl et al. [ 27 ] showed that its expression levels were lower in serum of ER-positive BC patients than healthy controls, whereas we show that its levels in HER2-positive patients who do not express ER were increased. In addition, miR-365 was also described to be oncogenic. Overexpression of miR-365 promoted cell proliferation and invasion through targeting ADAMTS-1 (a disintegrin and metalloproteinase with thrombospondin motifs) in BC cells [ 28 ]. In our study, significantly higher levels of exosomal miR-376c and miR-382 were observed in TNBC patients, but not in HER2-positive BC patients. Upregu- lated levels of miR-376c [ 29 ] and miR-382 [ 30 ] were also detected in plasma and serum of BC patients (regardless of the subtypes), respectively, by two previous studies. In BC, miR-382 targeted and repressed the Ras GTPase superfamily member RERG (Ras-related and estrogen- regulated growth inhibitor), to attenuate the inhibitory effects of RERG on the oncogenic Ras/ERK pathway. Thereby, miR-382 promoted BC cell viability, clonogeni- city, survival, migration, invasion and in vivo tumori- genesis/metastasis [ 31 ]. Contrary, for example in oral squamous cancer, miR-376c seems to have tumor sup- pressive functions. Its overexpression in these cancer cells suppressed fission, proliferation, migration and invasion and induced cell apoptosis via targeting the transcription factor HOXB7 [ 32 ]. Finally, we found that the levels of exosomal miR-422a were downregulated in HER2-positive BC patients, whereas the levels of exosomal miR-433 were upregulated in TNBC patients, but till now, quantitative data on these miRNAs have not been published for BC pa- tients. It was reported that in BC stem cells, upregulation of miR-422a attenuated microsphere formation, prolifera- tion, and tumor formation via suppressing the PLP2 (Pro- teolipid protein 2) expression [ 33 ]. Moreover, miR-433 repressed Rap1a, a small G protein of the Ras guanosine triphosphatase (GTPase) superfamily that activates the MAPK signaling pathway, and thus repressed cell migra- tion and proliferation and induced apoptosis in BC [ 34 ]. In addition, miR-433 targeted AKT3 in BC [ 35 ]. These findings highlight miR-422a and miR-433 as tumor sup- pressor genes.
Among women, breastcancer is the most frequent type of cancer, with an estimated 1.67 million new cancer cases diagnosed in 2012, and accounts for approximately 25% of all can- cers in women. But despite the fact that therapy prognoses are relatively good, breastcancer is still the second leading cause of cancer mortality in women (522,000 deaths in 2012) (World Health Organization). Like other cancers, breastcancer is a heterogeneous disease with diverse morphological and molecular features. Among parameters such as tumor size, histological grade, lymph node involvement, hormone receptor status and metastases for- mation it is currently classified into five main molecular classes: luminal A, luminal B, basal- like, ErbB2-positive and unclassified breastcancer subtypes. The basal-like subtype consti- tutes approximately 20% of all breast cancers and is also referred to as triple-negativebreastcancer because it frequently lacks expression of estrogen, progesterone and ErbB2/HER2 receptors. While the presence of estrogen and progesterone receptors allows a better clinical prognosis, as those cancers respond to hormone therapy, the basal-like and ErbB2-positive subtypes are more aggressive and are characterized by a higher risk of early relapse and a higher metastatic potential (Patel et al., 2007; Sørlie, 2007; Nishimura and Arima, 2008). De- pendent on the cancer subtype and the state of disease progression, cancer treatment com- prises one or the combination of the following options: surgery, radiation, chemotherapy, im- munotherapy, hormone therapy and gene therapy. Nevertheless the prerequisite for suc- cessful treatment is the detection of cancer in early stages and furthermore a profound un- derstanding of the underlying molecular mechanisms to refine therapeutic strategies. In this context, the field of miRNAs is of increasing interest as miRNAs function as key regulators of gene expression and are frequently subject to change during the development of human dis- eases, including cancer. Consequently, they have led to the discovery of a completely new repertoire of promising tools for diagnostic and therapeutic purposes.
Insulin-like growth factor-I receptor (IGF-IR) is integral to cancer cell proliferation, survival, migration, and invasion, and resistance to anti-cancer therapies in many human malignancies including breastcancer. Within the last few years several drugs targeting IGF-IR have entered clinical trials and are showing promising early results. One of the integral goals of my thesis is to identify patients who are most likely to benefit from therapy. The Lee Laboratory previously reported an IGF gene expression signature, based upon genes induced or repressed by IGF-I, which correlated with poor prognosis in breastcancer. Confirming that this signature can measure IGF activity, I report here that the signature is reversed in three different cancer models (cell lines or xenografts) treated with three different anti-IGF-IR therapies. The Lee laboratory originally reported that the IGF signature was present in triple- negative human breast cancers (TNBC), and I found here that the signature is similarly present in TNBC cell lines. Supporting a role for IGF-IR signaling in this subtype of breastcancer, I found that TNBC cell lines were especially sensitive to an IGF-IR tyrosine kinase inhibitor (BMS-754807), and that sensitivity was significantly correlated to expression of the IGF gene signature. Consistent with this, comparative gene expression analysis among the most resistant and sensitive cell lines identified 114 differentially expressed genes which identified TNBC as being sensitive. To examine this association further we determined levels and activity of the IGF-IR in several recently developed primary human TNBC tumorgraft models. I found high activity in many models, and chose the TNBC model MC1, which had the highest levels of both IGF signature score and IGF-IR expression and activity, for testing an anti-IGF-IR tyrosine kinase inhibitor (BMS-754807) in vivo. MC1 tumorgrafts treated with BMS-754807 as a single agent showed growth inhibition, and in combination with chemotherapy tumor regression occurred until no tumor was palpable. This regression was associated with reduced proliferation, increased apoptosis, and mitotic catastrophe. These data provide a clear biological rationale to test anti-IGF-IR therapy in combination with chemotherapy in patients with TNBC.
Abstract We aimed to analyse the impact of breastcancer (BC) subtypes on the clinical course of disease with special emphasis on the occurrence of brain metastases (BM) and outcome in an elderly BC population. A total number of 706 patients C65 years receiving treatment for BC from 2007 to 2011 were identified from a BC database. 62 patients diagnosed with DCIS and 73 patients with incomplete datasets were excluded, leaving 571 patients for this analysis. Patient characteristics, biological tumour subtypes, and clinical outcome including overall survival (OS) were obtained by retrospective chart review. 380/571 (66, 5 %) patients aged 65–74 years were grouped among the young-old, 182/571 (31.9 %) patients aged 75–84 years among the old–old, and 29/571 (5.1 %) patients aged C85 years among the oldest-old. 392/571 (68.8 %) patients presented with luminal BC, 119/571 (20.8 %) with HER2- positive, and 59/571 (10.3 %) with triple-negative BC (TNBC). At 38 months median follow-up, 115/571 (20.1 %) patients presented with distant recurrence. A higher recurrence rate was observed in the HER2-positive subtype (43/119 (36.1 %)), as compared to TNBC (15/59
Another interesting ADC is SYD985, a combina- tion of trastuzumab and the alkylating agent duocar- mazine . Again, the drug was tested in a phase I dose-escalation study with expansion cohorts in- cluding HER2-positive MBC, HER2-low expressing/ hormone-receptor (HR) positive MBC, triple-negative MBC (mTNBC) and other solid cancers with a HER2 expression of a least IHC 1+. Patients were heavily pretreated with a median of six prior treatment lines in all breastcancer subtypes. Of note, 92% of HER2- positive patients had prior exposure to trastuzumab, 80% to T-DM1, 46% lapatinib and 30% to pertuzumab. ORR in HER2-postive subjects (n = 48) was 33% (ORR prior T-DM1 treatment 29%); progression-free sur- vival (PFS) was 9.4 months (95% CI 4.5–12.5) and 8.3 months (95% CI 4.1–15), respectively. Of note, rel- evant clinical activity was also observed in HER2-low expressing/HR-positive and mTNBC patients as well (ORR 27% and 40%, respectively), although the PFS in these cohorts was shorter. While treatment was overall well-tolerated, 28 patients (safety population
Growing evidence supports the increased clinical effi- cacy of DNA-targeting therapies in breast cancers har- boring BRCA1 and/or BRCA2 mutations as BRCA func- tion is pivotal to DNA-damage response [ 1 ]. BRCA mutations are observed in approximately 5–10% of unselected breast cancers and 20–40% of all triple- negativebreast cancers (TNBCs). Up to 15% more have been hypothesized to express non-BRCA-related alterations in the DNA repair pathway of homologous recombination (HR) repair [ 2 – 4 ]. TNBCs typically ex- press few therapeutic targets; defining a predictive marker to identify patients that will most likely bene- fit from DNA targeting agents, such as platinum salts and poly-ADP-ribose polymerase (PARP) inhibitors, may therefore expand the therapeutic armamentar- ium for a clinically highly relevant subset of patients with breastcancer.
In recent decades, global gene expression profiling (GEP) studies of BC have provided a more established molecular classification system and identified distinct clusters or intrinsic subtypes based on the quantitative expression of several genes (transcriptome profiles). By using the expression of a subset (n = 496) of differentially expressed genes in GEP study, Perou and colleagues were able to identify two main clusters appeared to be related to ER expression, which allows to classify BC in 4 main classifications: luminal (with further differentiation in A and B), basal-like, HER2-positive and normal breast-like type [11, 12, 41]. The ER positive cluster was enriched with ER, ER-related genes and other genes characteristic of the luminal epithelial cells, herein this class was termed as ‘luminal’. The luminal cluster was further stratified into subclasses with at least two distinct subclasses reported in following studies: luminal A and luminal B subtypes. Compared with luminal B tumors, luminal A tumors express higher levels of ER and GATA3 that regulates luminal epithelial cell differentiation in the mammary gland , whereas luminal B tumors more often express HER1, HER2, and/or cyclin E1. Most studies indicated that luminal B tumors were associated with a worse prognosis than tumors of the luminal A class [12, 35]. The other major cluster with ER negative shows three distinct subclasses termed ‘HER2 positive’, ‘basal-like’ and ‘normal breast-like’. The HER2 subgroup is characterized by overexpression of HER2 and other genes concerning to the HER2 amplicon. The basal-like class is dominated by TNBCs, characterized by positive expression of genes typical of myoepithelial/basal epithelial cells, such as basal cytokeratin. The normal breast-like class displays a triple-negative phenotype but has gene expression similar to patterns found in normal breast tissue samples. These so-called “intrinsic BC subtypes” provide the basis of a molecular taxonomy of BC and they exhibit special molecular characteristics as well as different prognostic impact [43, 44].
54 microenvironment, the exosome shuttle of miR-93 could contribute to increase cell invasion (97). By the way, it was reported that upregulation of miR-93 promoted cell migration, invasion and proliferation in BC, as well as participated in regulating angiogenesis in cancers (98-100). Moreover, PTEN (Phosphatase Tensin Homolog) seems to be a target of miR-93, and consequently, miR-93 may regulate the activity of PI3K/Akt (Phosphoinositide 3-kinase/ Protein Kinase B) pathway (98). Previously, we observed higher transcript concentrations of circulating miR-93 in primary BC patients than in healthy women, but not in BC patient with metastasis (90). However, in the present study the enrichment of miR-93 in exosomes from BC patients was only of borderline significance. To date, I only found one article that quantified miR-93 in exosomes from BC patients. This study by Sueta et al. showed that the levels of miR-93 in tumor tissues was upregulated, but downregulated in exosomes from serum of patients with recurrence compared with those with no recurrence (101). I did not observe such an association of exosomal miR-93 with recurrence. This discrepancy could be explained by the small cohort used in that study that quantified exosomal miR-93, in only 16 recurrent and 16 non-recurrent BC patients. Furthermore, Kolacinska et al. found that the levels of miR-93 were higher in biopsy cells from ER- and PR-negative BC patients than from ER- and PR-positive BC (102). In contrast, I observed lower levels of exosomal miR-93 in PR-negative BC patients than in PR-positive BC. The different results may be explained by the specific packaging of miRNAs in exosomes. I also detected that the levels of exosomal miR-93 were lower in ER-, PR- and triple-negative BC patients than in DCIS patients, whereas ER- and PR-positive BC patients had higher levels of this miRNA than healthy women. Nonetheless, these data demonstrate differently deregulated levels of miRNAs between exosomes and tumor tissues, and a selective packaging process of miRNAs into exosomes that is not related to their expression levels in the primary tumor.
Comparing the results obtained from tissue-derived spheroids according to hormone receptor status showed that a higher treatment efficacy to anthracycline-taxan combination treatment was found for hormone recep- tor negative tissue samples. This difference in response confirm results published by Kaufmann et al. [ 59 ] which also showed a similar in vitro resistance to Adriamycin for HR− primary breast cell culture. Interestingly, tis- sue spheroids recapitulate clinical findings that a triplenegative tumor biology is associated with a high rate of pCR after chemotherapy [ 60 ]. An implicated mecha- nism for these observations was published recently by Lahsaee et al. [ 61 ]. Here, a reduced PRP4 K expres- sion of the estrogen signaling pathway correlated with a reduced response to paclitaxel treatment. Similarly, high grade tissue spheroids consistently responded better to the anthracycline treatment. Surprisingly, treatment with 5-FU-based single- or combination treatment was found to be more effective for high-grade tissue samples, as well as to smaller tumors and node- negative patients. As mentioned above the use of 5-FU is under discussion, however distinct patient subgroups may profit from the application of this drug as an alter- native to a taxane.