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Simple Summary: HER2-low (IHC 1+ or IHC 2+/ISH-) breast cancer (BC) is an emerging subtype of BC with promising results with antibody drug conjugate (ADC) in the metastatic setting. In the early setting, few data have been reported regarding the predictive and prognostic impact of HER2-low status in triple-negative BC (TNBC). Purpose: Investigates the link between HER2 status and histological response after neoadjuvant chemotherapy in patients with early TNBC. Methods: We retrieved clinical and anatomopathological data retrospectively from 449 patients treated for the first time with standard neoadjuvant chemotherapy for early unilateral BC between 2005 and 2020. The primary endpoint was pathological complete response (pCR, i.e., ypT0 ypN0), according to HER2 status. Secondary endpoints included invasive disease-free survival (I-DFS) and overall survival (OS). Results: 437 patients were included, and 121 (27.7%) patients had HER2-low tumours. The pCR rate was not significantly different between the HER2-low group vs. the HER2-0 group (35.7% versus 41.8%, p = 0.284) in either univariate analysis or multivariate analysis adjusted for TNM classification and grade (odds ratio [OR] = 0.70, confidence interval [CI] 95% 0.45–1.08). With a median follow-up of 72.9 months, no significant survival differences were observed between patients with HER2-low tumours vs. patients with HER2-0 tumours in terms of I-DFS (p = 0.487) and OS (p = 0.329). Conclusions: In our cohort, HER2 status was not significantly associated with pCR in a manner consistent with data published recently on TNBC. However, the prognostic impact of HER2-low expression among TNBC patients warrants further evaluation. [ABSTRACT FROM AUTHOR]

Background: Treatment of patients with residual disease after neoadjuvant chemotherapy for breast cancer is an unmet clinical need. We hypothesised that tumour subclones showing expansion in residual disease after chemotherapy would contain mutations conferring drug resistance.Methods: We studied oestrogen receptor and/or progesterone receptor-positive, HER2-negative tumours from 42 patients in the EORTC 10994/BIG 00-01 trial who failed to achieve a pathological complete response. Genes commonly mutated in breast cancer were sequenced in pre and post-treatment samples.Results: Oncogenic driver mutations were commonest in PIK3CA (38% of tumours), GATA3 (29%), CDH1 (17%), TP53 (17%) and CBFB (12%); and amplification was commonest for CCND1 (26% of tumours) and FGFR1 (26%). The variant allele fraction frequently changed after treatment, indicating that subclones had expanded and contracted, but there were changes in both directions for all of the commonly mutated genes.Conclusions: We found no evidence that expansion of clones containing recurrent oncogenic driver mutations is responsible for resistance to neoadjuvant chemotherapy. The persistence of classic oncogenic mutations in pathways for which targeted therapies are now available highlights their importance as drug targets in patients who have failed chemotherapy but provides no support for a direct role of driver oncogenes in resistance to chemotherapy. CLINICALTRIALS.GOV: EORTC 10994/BIG 1-00 Trial registration number NCT00017095. [ABSTRACT FROM AUTHOR]

Background: CirCe01 trial aimed to assess the clinical utility of circulating tumour cell (CTC)-based monitoring in metastatic breast cancer (MBC) patients beyond the third line of chemotherapy (LC).Methods: CirCe01 was a prospective, multicentre, randomised trial (NCT01349842) that included patients with MBC after two systemic LC. Patients with ≥5 CTC/7.5 mL (CellSearch®) were randomised between the CTC-driven and the standard arm. In the CTC arm, changes in CTC count were assessed at the first cycle of each LC; patients in whom CTC levels predicted early tumour progression had to switch to a subsequent LC.Results: Greater than or equal to 5 CTC/7.5 mL were observed in N = 101/204 patients. In the CTC arm (N = 51), 43 (83%) and 18 (44%) patients completed CTC monitoring in the third and fourth lines, respectively, and 18 (42%) and 11 (61%) of these patients, respectively, had no CTC response. Thirteen (72%) and 5 (46%) of these patients underwent early switch to the next LC. Overall survival was not different between the two arms (hazard ratio = 0.95, 95% confidence interval = [0.6;1.4], p = 0.8). In subgroup analyses, patients with no CTC response who switched chemotherapy experienced longer survival than patients who did not.Conclusions: Due to the limited accrual and compliance, this trial failed to demonstrate the clinical utility of CTC monitoring.Clinical Trial Registration: NCT, NCT01349842, https://clinicaltrials.gov/ct2/show/NCT01349842 , registered 9 May 2011. [ABSTRACT FROM AUTHOR]

Background: Breast cancer is the most common cancer in women and the first cancer concerning mortality. Metastatic breast cancer remains a disease with a poor prognosis and about 30% of women diagnosed with an early stage will have a secondary progression. Metastatic breast cancer is an incurable disease despite significant therapeutic advances in both supportive cares and targeted specific therapies. In the management of a metastatic patient, each clinician follows a highly complex and strictly personal decision making process. It is based on a number of objective and subjective parameters which guides therapeutic choice in the most individualized or adapted manner.Methods/design: The main objective is to integrate massive and heterogeneous data concerning the patient's environment, personal and familial history, clinical and biological data, imaging, histological results (with multi-omics data), and microbiota analysis. These characteristics are multiple and in dynamic interaction overtime. With the help of mathematical units with biological competences and scientific collaborations, our project is to improve the comprehension of treatment response, based on health clinical and molecular heterogeneous big data investigation.Discussion: Our project is to prove feasibility of creation of a clinico-biological database prospectively by collecting epidemiological, socio-economic, clinical, biological, pathological, multi-omic data and to identify characteristics related to the overall survival status before treatment and within 15 years after treatment start from a cohort of 300 patients with a metastatic breast cancer treated in the institution.Trial Registration: ClinicalTrials.gov identifier (NCT number): NCT03958136 . Registration 21st of May, 2019; retrospectively registered. [ABSTRACT FROM AUTHOR]

Introduction: Onapristone is a type I progesterone receptor (PR) antagonist, which prevents PR- mediated DNA transcription. Onapristone is active in multiple preclinical models and two prior studies demonstrated promising activity in patients with breast cancer. We conducted a study of extended release (ER) Onapristone to determine a recommended dose and explore the role of transcriptionally-activated PR (APR), detected as an aggregated subnuclear distribution pattern, as a predictive biomarker. Methods: An open-label, multicenter, randomized, parallel-group, phase 1 study (target n = 60; NCT02052128) included female patients ≥18 years with PRpos tumors. APR analysis was performed on archival tumor tissue. Patients were randomized to five cohorts of extended release (ER) onapristone tablets 10, 20, 30, 40 or 50 mg BID, or immediate release 100 mg QD until progressive disease or intolerability. Primary endpoint was to identify the recommended phase 2 dose. Secondary endpoints included safety, clinical benefit and pharmacokinetics. Results: The phase 1 dose escalation component of the study is complete (n = 52). Tumor diagnosis included: endometrial carcinoma 12; breast cancer 20; ovarian cancer 13; other 7. Median age was 64 (36–84). No dose limiting toxicity was observed with reported liver function test elevation related only to liver metastases. The RP2D was 50 mg ER BID. Median therapy duration was 8 weeks (range 2–44), and 9 patients had clinical benefit ≥24 weeks, including 2 patients with APRpos endometrial carcinoma. Conclusion: Clinical benefit with excellent tolerance was seen in heavily pretreated patients with endometrial, ovarian and breast cancer. The data support the development of Onapristone in endometrial endometrioid cancer. Onapristone should also be evaluated in ovarian and breast cancers along with APR immunohistochemistry validation. [ABSTRACT FROM AUTHOR]

Background: Overexpression of fibroblast growth factor receptor 1 (FGFR1), found in ≤8% of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer cases, is correlated with decreased overall survival and resistance to endocrine therapy (ET). Dovitinib, a potent FGFR inhibitor, has demonstrated antitumor activity in heavily pretreated patients with FGFR pathway-amplified breast cancer.Methods: In this randomized, placebo-controlled phase II trial, we evaluated whether the addition of dovitinib to fulvestrant would improve outcomes in postmenopausal patients with HR+, HER2- advanced breast cancer that had progressed during or after prior ET. Patients were stratified by FGF pathway amplification and presence of visceral disease, and they were randomized 1:1 to receive fulvestrant plus dovitinib or placebo. The primary endpoint was progression-free survival (PFS).Results: From 15 May 2012 to 26 November 2014, 97 patients from 36 centers were enrolled. The frequency of FGF pathway amplification was lower than anticipated, and the study was terminated early owing to slow accrual of patients with FGF pathway amplification. The median PFS (95% CI) was 5.5 (3.8-14.0) months vs 5.5 (3.5-10.7) months in the dovitinib vs placebo arms, respectively (HR, 0.68; did not meet predefined efficacy criteria). For the FGF pathway-amplified subgroup (n = 31), the median PFS (95% CI) was 10.9 (3.5-16.5) months vs 5.5 (3.5-16.4) months in the dovitinib vs placebo arms, respectively (HR, 0.64; met the predefined superiority criteria). Frequently reported adverse events in the dovitinib (diarrhea, nausea, vomiting, asthenia, and headache) and placebo (diarrhea, fatigue, nausea, and asthenia) arms were mostly low grade.Conclusions: The safety profile of dovitinib plus fulvestrant was consistent with the known safety profile of single-agent dovitinib. Dovitinib in combination with fulvestrant showed promising clinical activity in the FGF pathway-amplified subgroup. However, the data reported herein should be interpreted with caution, given that fewer PFS events occurred in the FGF pathway-amplified patients than was expected and that an effect of dovitinib regardless of FGR pathway amplification status cannot be excluded, because the population was smaller than expected.Trial Registration: ClinicalTrials.gov identifier: NCT01528345 . Registered 31 January 2012. [ABSTRACT FROM AUTHOR]

Background: Major advances have been achieved in the characterization of early breast cancer (eBC) genomic profiles. Metastatic breast cancer (mBC) is associated with poor outcomes, yet limited information is available on the genomic profile of this disease. This study aims to decipher mutational profiles of mBC using next-generation sequencing.Methods and Findings: Whole-exome sequencing was performed on 216 tumor-blood pairs from mBC patients who underwent a biopsy in the context of the SAFIR01, SAFIR02, SHIVA, or Molecular Screening for Cancer Treatment Optimization (MOSCATO) prospective trials. Mutational profiles from 772 primary breast tumors from The Cancer Genome Atlas (TCGA) were used as a reference for comparing primary and mBC mutational profiles. Twelve genes (TP53, PIK3CA, GATA3, ESR1, MAP3K1, CDH1, AKT1, MAP2K4, RB1, PTEN, CBFB, and CDKN2A) were identified as significantly mutated in mBC (false discovery rate [FDR] < 0.1). Eight genes (ESR1, FSIP2, FRAS1, OSBPL3, EDC4, PALB2, IGFN1, and AGRN) were more frequently mutated in mBC as compared to eBC (FDR < 0.01). ESR1 was identified both as a driver and as a metastatic gene (n = 22, odds ratio = 29, 95% CI [9-155], p = 1.2e-12) and also presented with focal amplification (n = 9) for a total of 31 mBCs with either ESR1 mutation or amplification, including 27 hormone receptor positive (HR+) and HER2 negative (HER2-) mBCs (19%). HR+/HER2- mBC presented a high prevalence of mutations on genes located on the mechanistic target of rapamycin (mTOR) pathway (TSC1 and TSC2) as compared to HR+/HER2- eBC (respectively 6% and 0.7%, p = 0.0004). Other actionable genes were more frequently mutated in HR+ mBC, including ERBB4 (n = 8), NOTCH3 (n = 7), and ALK (n = 7). Analysis of mutational signatures revealed a significant increase in APOBEC-mediated mutagenesis in HR+/HER2- metastatic tumors as compared to primary TCGA samples (p < 2e-16). The main limitations of this study include the absence of bone metastases and the size of the cohort, which might not have allowed the identification of rare mutations and their effect on survival.Conclusions: This work reports the results of the analysis of the first large-scale study on mutation profiles of mBC. This study revealed genomic alterations and mutational signatures involved in the resistance to therapies, including actionable mutations. [ABSTRACT FROM AUTHOR]

Background: Dogs spontaneously develop invasive mammary carcinoma with a high prevalence of the triple-negative (TN) subtype (lack of ER-Estrogen Receptor and PR-Progesterone Receptor expression, lack of HER2-Human Epidermal Growth Factor Receptor 2 overexpression), making this animal model relevant for investigating new therapeutic pathways. Insulin-like growth factor Type-1 receptor (IGF1R) is frequently overexpressed in primary human breast cancers, with a growing role in the TN phenotype. The purpose of this study was to investigate the Dog as a candidate model for IGF1R-overexpressing mammary carcinoma.Methods: 150 bitches with canine mammary carcinoma (CMC) and a known 2-year follow-up were retrospectively included. IGF1R expression was assessed by immunohistochemistry (IHC) using a similar scoring system as for HER2 in breast cancer. The prognostic value of the IGF1R expression was assessed in terms of overall and specific survival as well as disease-free interval (DFI).Results: 47 CMC (31 %) were classified as luminal and 103 (69 %) as triple-negative (TN-CMC). 41 % of CMC overexpressed IGF1R (IHC score 3+) of which 76 % were TN-CMC and 62 % grade III. IGF1R overexpression was associated with aggressive features including lymphovascular invasion, histological grade III, low ER expression and the TN phenotype. Univariate and multivariate analyses revealed that IGF1R overexpression was associated with shorter overall and specific survivals and shorter DFI in TN-CMC.Conclusions: IGF1R overexpression is common and related to a poor outcome in canine invasive mammary carcinoma, particularly in the triple negative subtype, as in human breast cancer. Preclinical studies using the Dog as a spontaneous animal model could be considered to investigate new therapies targeting IGF1R in triple-negative breast cancer. [ABSTRACT FROM AUTHOR]

Simple Summary: In the recent years, several deep learning methods for medical image segmentation have been developed for different purposes such as diagnosis, radiotherapy planning or to correlate images findings with other clinical data. However, few studies focus on longitudinal images and response assessment. To the best of our knowledge, this is the first study to date evaluating the use of automatic segmentation to obtain imaging biomarkers that can be used to assess treatment response in patients with metastatic breast cancer. Moreover, the statistical analysis of the different biomarkers shows that automatic segmentation can be successfully used for their computation, reaching similar performances compared to manual segmentation. Analysis also demonstrated the potential of the different biomarkers including novel/original ones to determine treatment response. Metastatic breast cancer patients receive lifelong medication and are regularly monitored for disease progression. The aim of this work was to (1) propose networks to segment breast cancer metastatic lesions on longitudinal whole-body PET/CT and (2) extract imaging biomarkers from the segmentations and evaluate their potential to determine treatment response. Baseline and follow-up PET/CT images of 60 patients from the EPICURE s e i n m e t a study were used to train two deep-learning models to segment breast cancer metastatic lesions: One for baseline images and one for follow-up images. From the automatic segmentations, four imaging biomarkers were computed and evaluated: SUL p e a k , Total Lesion Glycolysis (TLG), PET Bone Index (PBI) and PET Liver Index (PLI). The first network obtained a mean Dice score of 0.66 on baseline acquisitions. The second network obtained a mean Dice score of 0.58 on follow-up acquisitions. SUL p e a k , with a 32% decrease between baseline and follow-up, was the biomarker best able to assess patients' response (sensitivity 87%, specificity 87%), followed by TLG (43% decrease, sensitivity 73%, specificity 81%) and PBI (8% decrease, sensitivity 69%, specificity 69%). Our networks constitute promising tools for the automatic segmentation of lesions in patients with metastatic breast cancer allowing treatment response assessment with several biomarkers. [ABSTRACT FROM AUTHOR]

Background. This randomized phase II trial was designed to compare the rate of pathologic complete response (pCR) induced by neoadjuvant cyclophosphamide plus doxorubicin (AC) followed by ixabepilone or paclitaxel in women with early stage breast cancer (BC). Expression of βIII-tubulin as a predictive marker was also evaluated. Patients and Methods. Women with untreated, histologically confirmed primary invasive breast adenocarcinoma received four cycles of AC followed by 1:1 randomization to either ixabepilone 40 mg/m2 (3-hour infusion) every 3 weeks for four cycles (n = 148) or weekly paclitaxel 80 mg/m2 (1-hour infusion) for 12 weeks (n = 147). All patients underwent a core needle biopsy of the primary cancer for molecular marker analysis prior to chemotherapy. βIII-Tubulin expression was assessed using immunohistochemistry. Results. There was no significant difference in the rate of pCR in the ixabepilone treatment arm (24.3%; 90% confidence interval [CI],18.6-30.8)and the paclitaxel treatment arm (25.2%;90%CI, 19.4-31.7). βIII-Tubulin-positive patients obtained higher pCR Rates compared with βIII-tubulin-negative patients in both treatment arms; however, βIII-tubulin expression was not significantly associated with a differential response to ixabepilone or paclitaxel. The safety profiles of both regimens were generally similar, although neutropenia occurred more frequently in the ixabepilone arm (grade 3/4: 41.3% vs. 8.4%). The most common nonhematologic toxicity was peripheral neuropathy. Conclusions. Neoadjuvant treatment of early stage BC with AC followed by ixabepilone every 3 weeks or weekly paclitaxel was well tolerated with no significant difference in efficacy. Higher response rates were observed among βIII-tubulin-positive patients. [ABSTRACT FROM AUTHOR]

Owing to the increased number of patients treated with anthracycline-based adjuvant chemotherapy, there is a need for new effective and tolerable nonanthracycline regimens in metastatic breast cancer. Patients with HER2-negative metastatic breast cancer previously treated with anthracyclines in (neo)adjuvant setting were randomized to fully oral 3 weekly cycles of the combination of oral vinorelbine with capecitabine (V + C), to the same drugs alternating every three cycles (V↔C), or to the combination of docetaxel and capecitabine (D + C). V was given at 80 mg/m2 (after the first cycle at 60 mg/m2) on days 1 and 8 in the V + C arm and weekly in the V↔C arm, C at 1,000 mg/m2 bid from days 1 to 14, and D on day 1 at 75 mg/m2. The primary end point was disease control rate ( CR + PR + NC ≥ 3 months). A total of 139 patients were randomly assigned to V + C (44 patients), V↔C (47 patients), and D + C (48 patients). After an independent review, the disease control rate in the intent-to-treat population in the V + C, V↔C, and D + C arms [95% CI] was 70.5% [54.8-83.2], 37.0% [23.2-52.5], and 70.8% [55.9-83.1], and the median overall survival 22.2, 19.4, and 24.2 months, respectively. When taken into account the disease control rate, the alternating V↔C regimen seems to be less effective compared with V + C or D + C combinations. Combinations of V + C or D + C showed similar efficacy and a different toxicity profile; V + C induced less neutropenia, infection, hand-foot syndrome, fatigue/asthenia, and alopecia, whereas D + C - less gastrointestinal toxicity. V + C combination constitutes a valuable fully oral alternative option to D + C in patients with metastatic breast cancer previously treated with anthracyclines in (neo)adjuvant setting, while offering the advantages of an all-oral treatment. [ABSTRACT FROM AUTHOR]

Patients and Methods. Between June 1997 and March 2000, a total of 1,999 patients (age <65) with localized, resectable, non-pretreated, unilateral breast cancer were randomly assigned to receive either standard FEC100 for 6 cycles or 3 cycles of FEC100 followed by 3 cycles of 100 mg/m2 docetaxel (FEC-D), both given every 21 days. Radiotherapy was mandatory after conservative surgery and tamoxifen was given for 5 years to hormone receptor (HR)- positive patients. Five-year DFS was the trial's main endpoint. Updated 8-year survival data are presented. Results. With a median follow-up of 92.8 months, 639 patients experienced at least one event. A total number of 383 deaths were registered. Eight-year DFS rates were 65.8% with FEC alone and 70.2% with FEC-D. OS rates at 8 years were 78% with FEC alone and 83.2% with FEC-D. Cox regression analysis adjusted for age and number of positive nodes showed a 15% reduction in the relative risk of relapse and a 25% reduction in the relative risk of death in favor of FEC-D. Significant relative risk reductions were observed in the HR-positive, HER2-positive, and Ki67≥20% subpopulations. [ABSTRACT FROM AUTHOR]

Background. The Hermine study observed the use of trastuzumab for metastatic breast cancer (MBC) in routine practice, including patients who received trastuzumab treatment beyond progression (TBP). Patients and Methods. The study observed 623 patients for ≥2 years. Treatment was given according to oncologists' normal clinical practices. Endpoints included duration of treatment, efficacy, and cardiac safety. The TBP subanalysis compared overall survival (OS) in 177 patients who received first-line trastuzumab and either continued trastuzumab for ≥30 days following progression or stopped at or before progression. Results. The median treatment duration was 13.3 months. In the first-, second-, and third-line or beyond treatment groups, the median time to progression (TTP) were 10.3 months, 9.0 months, and 6.3 months, and the median OS times were 30.3 months, 27.1 months, and 23.2 months, respectively. Heart failure was observed in 2.6% of patients, although no cardiac-associated deaths occurred. In the TBP subanalysis, the median OS duration from treatment initiation and time of disease progression were longer in patients who continued receiving trastuzumab TBP (>27.8 months and 21.3 months, respectively) than in those who stopped (16.8 months and 4.6 months, respectively). However, the groups were not completely comparable, because patients who continued trastuzumab TBP had better prognoses at treatment initiation. The median TTP was longer in patients who continued trastuzumab TBP (10.2 months) than in those who stopped (7.1 months). Conclusion. The Hermine findings confirm that the pivotal trials of first-line trastuzumab treatment in MBC patients are applicable in clinical practice. The subanalysis suggests that trastuzumab TBP offers a survival benefit to MBC patients treated with first-line trastuzumab. [ABSTRACT FROM AUTHOR]

Simple Summary: Anthracyclines are among the most active chemotherapies in breast cancer (BC). However, they can cause structural and cumulative dose-related cardiac damage; hence, they require careful administration after preliminary functional cardiac assessment and subsequent monitoring, along with a limitation in the cumulative dose delivered. Non-pegylated liposomal doxorubicin (NPLD) has been precisely developed to optimize the doxorubicin toxicity profile, while retaining its therapeutic efficacy, thanks to a reduced diffusion in normal tissues with preserved drug penetrance into cancer sites. This has allowed administration of NPLD beyond a conventional doxorubicin maximum cumulative dose, as well as in patients with cardiac comorbilities or anthracycline pretreatment. At present, NPLD is approved in Europe and Canada in combination with cyclophosphamide as the first line of metastatic HER2-negative BC. However, given the increasing complexity of the therapeutic scenario in this setting, we have carefully revised the most updated literature on the topic and dissected the potential role of NPLD in the evolving therapeutic algorithms. Anthracyclines are among the most active chemotherapies (CT) in breast cancer (BC). However, cardiotoxicity is a risk and peculiar side effect that has been limiting their use in clinical practice, especially after the introduction of taxanes. Non-pegylated liposomal doxorubicin (NPLD) has been developed to optimize the toxicity profile induced by anthracyclines, while maintaining its unquestionable therapeutic index, thanks to its delivering characteristics that increase its diffusion in tumor tissues and reduce it in normal tissues. This feature allows NPLD to be safely administered beyond the standard doxorubicin maximum cumulative dose of 450–480 mg/m2. Following three pivotal first-line phase III trials in HER2-negative metastatic BC (MBC), this drug was finally approved in combination with cyclophosphamide in this specific setting. Given the increasing complexity of the therapeutic scenario of HER2-negative MBC, we have carefully revised the most updated literature on the topic and dissected the potential role of NPLD in the evolving therapeutic algorithms. [ABSTRACT FROM AUTHOR]

Background: ADAM8 (a disintegrin and metalloproteinase 8) protein promotes the invasive and metastatic phenotype of triple-negative breast cancer (TNBC) cells. High ADAM8 expression in breast cancer patients is an independent predictor of poor prognosis. Here, we investigated whether ADAM8 regulates specific miRNAs, their roles in aggressive phenotype, and potential use as biomarkers of disease.Methods: Microarray analysis was performed on RNA from MDA-MB-231 cells after transient ADAM8 knockdown using TaqMan miRNA cards. Changes in miRNA levels were confirmed using two ADAM8 siRNAs in TNBC cell lines. Kinase inhibitors, β1-integrin antagonist antibody, and different forms of ADAM8 were employed to elucidate the signaling pathway required for miR-720 expression. miR-720 levels were modulated using a specific antagomiR or a mimic, and effects on aggressive phenotype of TNBC cells were determined using Boyden chamber and 3D-Matrigel outgrowth assays. Plasma was isolated from mice before and after implantation of MDA-MB-231 cells and analyzed for miR-720 levels. Serum samples of TNBC patients were evaluated for their ADAM8 and miR-720 levels.Results: We identified 68 miRNAs differentially regulated upon ADAM8 knockdown, including decreased levels of secreted miR-720. Ectopic overexpression of wild-type ADAM8 or forms that lack metalloproteinase activity similarly induced miR-720 levels. The disintegrin and cysteine-rich domains of ADAM8 were shown to induce miR-720 via activation of a β1-integrin to ERK signaling cascade. Knockdown of miR-720 led to a significant decrease in migratory and invasive abilities of TNBC cells. Conversely, miR-720 overexpression rescued these properties. A profound increase in plasma levels of miR-720 was detected 7 days after TNBC cell inoculation into mouse mammary fat pads when tumors were barely palpable. Concordantly, miR-720 levels were found to be significantly higher in serum samples of TNBC patients with high ADAM8 expression.Conclusions: We have shown for the first time that miR-720 is induced by ADAM8 signaling via ERK and plays an essential role in promoting the aggressive phenotype of TNBCs. miR-720 is elevated in serum of patients with ADAM8-high TNBC and, in a group with other miRNAs downstream of ADAM8, holds promise as a biomarker for early detection of or treatment response of ADAM8-positive TNBCs. [ABSTRACT FROM AUTHOR]