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Demographic changes in the world population will cause a significant increase in the number of new cases of cancer. To handle this challenge, societies will need to adapt how they approach cancer prevention and treatment, with changes to the development and uptake of innovative anticancer drugs playing an important role. However, there are obstacles to implementing innovative drugs in clinical practice. Prior to being incorporated into daily practice, the drug must obtain regulatory and reimbursement approval, succeed in changing the prescription habits of physicians, and ultimately gain the compliance of individual patients. Developing an anticancer drug and bringing it into clinical practice is, therefore, a lengthy and complex process involving multiple partners in several areas. To optimize patient treatment and increase the likelihood of implementing health innovation, it is essential to have an overview of the full process. This review aims to describe the process and discuss the hurdles arising at each step. [ABSTRACT FROM AUTHOR]

Introduction: Triple negative breast cancer (TNBC) is an aggressive BC subtype, associated with higher rates of relapse and shorter overall survival upon metastatic relapse. The advent of antibody-drug conjugates (ADC), able to deliver selectively potent chemotherapeutic agents, has demonstrated promising clinical activity, with the first approval of an ADC, i.e. Sacituzumab Govitecan, in the metastatic setting. This paperprovides the most recent data indicating the promise of this novel class of drugs, as potential tools to improve clinical outcomes of patients diagnosed with TNBC., Areas Covered: Upon review of the main characteristics of TNBC, and those of ADCs, an overview of the data from clinical trials assessing ADCs in TNBC is provided, including those that led to the first approval of such a drug for patients with metastatic disease; furthermore, several other ADCs targeting different proteins (over)expressed by TNBC undergo clinical development. Combinations of ADCs with other targeted agents are discussed; the most pertinent considerations for improving the chances of successful clinical development of ADCs in TNBC are provided., Expert Opinion: ADCs could further improve clinical outcomes of patients with TNBC, and successful development depends upon: i) successful triaging of patients with the right ADC, ii) technical optimization of ADCs to maximize the efficacy, while reducing toxicity, and iii) assess rationally chosen combinations with synergistic antitumor activity and acceptable safety profile.

Patients with advanced triple-negative breast cancer (TNBC) benefit from treatment with atezolizumab, provided that the tumor contains ≥1% of PD-L1/SP142-positive immune cells. Numbers of tumor-infiltrating lymphocytes (TILs) vary strongly according to the anatomic localization of TNBC metastases. We investigated inter-pathologist agreement in the assessment of PD-L1/SP142 immunohistochemistry and TILs. Ten pathologists evaluated PD-L1/SP142 expression in a proficiency test comprising 28 primary TNBCs, as well as PD-L1/SP142 expression and levels of TILs in 49 distant TNBC metastases with various localizations. Interobserver agreement for PD-L1 status (positive vs. negative) was high in the proficiency test: the corresponding scores as percentages showed good agreement with the consensus diagnosis. In TNBC metastases, there was substantial variability in PD-L1 status at the individual patient level. For one in five patients, the chance of treatment was essentially random, with half of the pathologists designating them as positive and half negative. Assessment of PD-L1/SP142 and TILs as percentages in TNBC metastases showed poor and moderate agreement, respectively. Additional training for metastatic TNBC is required to enhance interobserver agreement. Such training, focusing on metastatic specimens, seems worthwhile, since the same pathologists obtained high percentages of concordance (ranging from 93% to 100%) on the PD-L1 status of primary TNBCs.

Background: The role of adjuvant treatment in high-risk muscle-invasive urothelial carcinoma after radical surgery is not clear., Methods: In a phase 3, multicenter, double-blind, randomized, controlled trial, we assigned patients with muscle-invasive urothelial carcinoma who had undergone radical surgery to receive, in a 1:1 ratio, either nivolumab (240 mg intravenously) or placebo every 2 weeks for up to 1 year. Neoadjuvant cisplatin-based chemotherapy before trial entry was allowed. The primary end points were disease-free survival among all the patients (intention-to-treat population) and among patients with a tumor programmed death ligand 1 (PD-L1) expression level of 1% or more. Survival free from recurrence outside the urothelial tract was a secondary end point., Results: A total of 353 patients were assigned to receive nivolumab and 356 to receive placebo. The median disease-free survival in the intention-to-treat population was 20.8 months (95% confidence interval [CI], 16.5 to 27.6) with nivolumab and 10.8 months (95% CI, 8.3 to 13.9) with placebo. The percentage of patients who were alive and disease-free at 6 months was 74.9% with nivolumab and 60.3% with placebo (hazard ratio for disease recurrence or death, 0.70; 98.22% CI, 0.55 to 0.90; P<0.001). Among patients with a PD-L1 expression level of 1% or more, the percentage of patients was 74.5% and 55.7%, respectively (hazard ratio, 0.55; 98.72% CI, 0.35 to 0.85; P<0.001). The median survival free from recurrence outside the urothelial tract in the intention-to-treat population was 22.9 months (95% CI, 19.2 to 33.4) with nivolumab and 13.7 months (95% CI, 8.4 to 20.3) with placebo. The percentage of patients who were alive and free from recurrence outside the urothelial tract at 6 months was 77.0% with nivolumab and 62.7% with placebo (hazard ratio for recurrence outside the urothelial tract or death, 0.72; 95% CI, 0.59 to 0.89). Among patients with a PD-L1 expression level of 1% or more, the percentage of patients was 75.3% and 56.7%, respectively (hazard ratio, 0.55; 95% CI, 0.39 to 0.79). Treatment-related adverse events of grade 3 or higher occurred in 17.9% of the nivolumab group and 7.2% of the placebo group. Two treatment-related deaths due to pneumonitis were noted in the nivolumab group., Conclusions: In this trial involving patients with high-risk muscle-invasive urothelial carcinoma who had undergone radical surgery, disease-free survival was longer with adjuvant nivolumab than with placebo in the intention-to-treat population and among patients with a PD-L1 expression level of 1% or more. (Funded by Bristol Myers Squibb and Ono Pharmaceutical; CheckMate 274 ClinicalTrials.gov number, NCT02632409.)., (Copyright © 2021 Massachusetts Medical Society.)

Background: The APHINITY (BIG 4-11) study showed that pertuzumab significantly improved the rates of invasive disease-free survival among patients with human epidermal growth factor receptor 2 (HER2)-positive, operable breast cancer when added to adjuvant trastuzumab and chemotherapy. Because diarrhea was a common adverse event that could compromise treatment administration, we evaluated the incidence and management of diarrhea in the APHINITY study., Patients and Methods: The APHINITY trial is a prospective, randomized, multicenter, multinational, double-blind, placebo-controlled trial. The eligible patients were randomly assigned to receive standard adjuvant chemotherapy and 1 year of trastuzumab combined with pertuzumab or placebo. The diarrhea incidence, severity (National Cancer Institute common terminology criteria for adverse events, version 4.0), onset, and management were analyzed., Results: A total of 4805 patients were randomized. Diarrhea of any grade was the most common adverse event and occurred in 71% of patients in the pertuzumab arm versus 45% in the placebo arm. Diarrhea grade 3 to 4 was observed in 10% and 4% in the pertuzumab and placebo arms, respectively. The greatest incidence of diarrhea was reported during the concomitant administration of HER2-targeted therapy and taxane (61% vs. 34% of patients experienced an event with pertuzumab vs. placebo, respectively). A marked decrease was observed on chemotherapy cessation. Antidiarrheal agents were commonly used, and diarrhea rarely caused treatment dose modifications or discontinuation., Conclusion: Diarrhea was a common adverse event in the APHINITY study. Most episodes were low grade and were generally manageable with common antidiarrheal agents. The incidence of diarrhea was greater with the combination of a taxane and HER2-targeted treatment and decreased once chemotherapy was stopped., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Immune checkpoint inhibitor therapies targeting PD-1/PD-L1 are now the standard of care in oncology across several hematologic and solid tumor types, including triple negative breast cancer (TNBC). Patients with metastatic or locally advanced TNBC with PD-L1 expression on immune cells occupying ≥1% of tumor area demonstrated survival benefit with the addition of atezolizumab to nab-paclitaxel. However, concerns regarding variability between immunohistochemical PD-L1 assay performance and inter-reader reproducibility have been raised. High tumor-infiltrating lymphocytes (TILs) have also been associated with response to PD-1/PD-L1 inhibitors in patients with breast cancer (BC). TILs can be easily assessed on hematoxylin and eosin-stained slides and have shown reliable inter-reader reproducibility. As an established prognostic factor in early stage TNBC, TILs are soon anticipated to be reported in daily practice in many pathology laboratories worldwide. Because TILs and PD-L1 are parts of an immunological spectrum in BC, we propose the systematic implementation of combined PD-L1 and TIL analyses as a more comprehensive immuno-oncological biomarker for patient selection for PD-1/PD-L1 inhibition-based therapy in patients with BC. Although practical and regulatory considerations differ by jurisdiction, the pathology community has the responsibility to patients to implement assays that lead to optimal patient selection. We propose herewith a risk-management framework that may help mitigate the risks of suboptimal patient selection for immuno-therapeutic approaches in clinical trials and daily practice based on combined TILs/PD-L1 assessment in BC. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd., (© 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.)

Background: Trastuzumab-associated cardiotoxicity remains an issue for patients with HER2-positive breast cancer. This pooled analysis of 3 adjuvant trials investigated the incidence, timing, impact on treatment completion, and risk factors for trastuzumab-associated cardiotoxicity., Methods: This is an individual patient data level pooled analysis of HERA, NSBAP B-31, and NCCTG 9831 (Alliance Trials). Definitions of cardiac events were as per each individual study., Results: A total of 7445 patients enrolled in the 3 trials were included in the analysis, of which 4017 were in the trastuzumab and 3428 in the control (observation) arms, respectively. Median follow-up exceeded 10 years (119.2-137.2 months). Nearly all patients (97.4%) in the trastuzumab arms received anthracycline-based chemotherapy. In total, 452 patients in the trastuzumab arms experienced a cardiac event (11.3%), with most being mildly symptomatic or asymptomatic left ventricular ejection fraction (LVEF) decrease (351 patients, 8.7%). Severe congestive heart failure was more common in the trastuzumab arm (2.3%) than in the control arm (0.8%). Most cardiac events occurred during trastuzumab treatment (78.1%) and cardiac events were the main cause of discontinuation across the sample (10.0%); nevertheless, a large majority of patients completed trastuzumab treatment (76.2%). Baseline risk factors that were significantly associated with the development of cardiac events were baseline LVEF < 60%, hypertension, body mass index > 25, age ≥ 60 and, non-Caucasian ethnicity., Conclusion: One year of trastuzumab increases the risk of cardiac events, though most consist of asymptomatic or mildly symptomatic LVEF drops. Adjuvant trastuzumab should be considered a safe treatment from a cardiac standpoint for most patients. Trastuzumab-associated cardiotoxicity is the main cause of discontinuation and further research is needed to individualize prevention and management.

Background: Endocrine therapy-based neoadjuvant treatment for luminal breast cancer allows efficient testing of new combinations before surgery. The activation of the phosphatidylinositol-3-kinase (PI3K) pathway is a known mechanism of resistance to endocrine therapy. Taselisib is an oral, selective PI3K inhibitor with enhanced activity against PIK3CA-mutant cancer cells. The LORELEI trial tested whether taselisib in combination with letrozole would result in an increased proportion of objective responses and pathological complete responses., Methods: In this multicentre, randomised, double-blind, parallel-cohort, placebo-controlled phase 2, study, we enrolled postmenopausal women (aged ≥18 years) with histologically confirmed, oestrogen receptor (ER)-positive, HER2-negative, stage I-III, operable breast cancer, from 85 hospitals in 22 countries worldwide. To be eligible, patients had have an Eastern Cooperative Oncology Group (ECOG) performance status 0-1, adequate organ function, and had to have evaluable tumour tissue for PIK3CA genotyping. Patients were randomly assigned (1:1) by means of a permuted block algorithm (block size of four) via an interactive voice or web-based response system, to receive letrozole (2·5 mg/day orally, continuously) with either 4 mg of oral taselisib or placebo (on a 5 days-on, 2 days-off schedule) for 16 weeks, followed by surgery. Randomisation was stratified by tumour size and nodal status. Site staff, patients, and the sponsor were masked to treatment assignment. Coprimary endpoints were the proportion of patients who achieved an objective response by centrally assessed breast MRI and a locally assessed pathological complete response in the breast and axilla (ypT0/Tis, ypN0) at surgery in all randomly assigned patients and in patients with PIK3CA-mutant tumours. Analyses were done in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02273973, and is closed to accrual., Findings: Between Nov 12, 2014, and Aug 12, 2016, 334 participants were enrolled and randomly assigned to receive letrozole and placebo (n=168) or letrozole and taselisib (n=166). Median follow-up was 4·9 months (IQR 4·7-5·1). The study met one of its primary endpoints: the addition of taselisib to letrozole was associated with a higher proportion of patients achieving an objective response in all randomly assigned patients (66 [39%] of 168 patients in the placebo group vs 83 [50%] of 166 in the taselisib group; odds ratio [OR] 1·55, 95% CI 1·00-2·38; p=0·049) and in the PIK3CA-mutant subset (30 [38%] of 79 vs 41 [56%] of 73; OR 2·03, 95% CI 1·06-3·88; p=0·033). No significant differences were observed in pathological complete response between the two groups, either in the overall population (three [2%] of 166 in the taselisib group vs one [1%] of 168 in the placebo group; OR 3·07 [95% CI 0·32-29·85], p=0·37) or in the PIK3CA-mutant cohort (one patient [1%) vs none [0%]; OR not estimable, p=0·48). The most common grade 3-4 adverse events in the taselisib group were gastrointestinal (13 [8%] of 167 patients), infections (eight [5%]), and skin-subcutaneous tissue disorders (eight [5%]). In the placebo group, four (2%) of 167 patients had grade 3 or worse vascular disorders, two (1%) had gastrointestinal disorders, and two (1%) patients had grade 3 or worse infections and infestations. There was no grade 4 hyperglycaemia and grade 3 cases were asymptomatic. Serious adverse events were more common in the taselisib group (eight [5%] patients with infections and seven [4%] with gastrointestinal effects) than in the placebo group (one [1%] patient each with grade 3 postoperative wound and haematoma infection, grade 4 hypertensive encephalopathy, grade 3 acute cardiac failure, and grade 3 breast pain). One death occurred in the taselisib group, which was not considered to be treatment-related., Interpretation: The increase in the proportion of patients who achieved an objective response from the addition of taselisib to endocrine therapy in a neoadjuvant setting is consistent with the clinical benefit observed in hormone receptor-positive, HER2-negative, metastatic breast cancer., Funding: Genentech and F Hoffmann-La Roche., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background/aim: This study sought to determine whether an autoimmune background could identify patients with HER2-positive early breast cancer (EBC) who derive differential benefit from primary adjuvant trastuzumab-based therapy., Patients and Methods: HERA is an international randomized trial of 5,102 women with HER2-positive EBC, who were enrolled to either receive adjuvant trastuzumab or not. In this exploratory analysis, the interaction between autoimmune history and the magnitude of trastuzumab benefit was evaluated., Results: A total of 5,099 patients were included in the current analysis. Among them, 325 patients (6.4%) had autoimmune disease history, 295 of whom had active disease. Patients were randomly assigned to trastuzumab or no-trastuzumab groups. Similar reductions in the risk of events in patients with and without autoimmune history were observed (interaction p=0.95 for disease-free survival, and p=0.62 for overall survival)., Conclusion: No evidence of a differential benefit from trastuzumab in patients with a medical history of autoimmune disease was found., (Copyright© 2019, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

The prognosis of patients with early stage breast cancer has greatly improved in the past three decades. Following the first adjuvant endocrine therapy and chemotherapy trials, continuous improvements of clinical outcomes have been achieved through intense therapeutic escalation, albeit with increased health-care costs and treatment-related toxicities. In contrast to the advances achieved in surgery or radiotherapy, the identification of the patient subgroups that will derive clinical benefit from therapeutic escalation has proved to be a daunting process hindered by a lack of collaboration between scientific groups and by the pace of drug development. In the past few decades, initiatives towards de-escalation of systemic adjuvant treatment have achieved success. Herein, we summarize attempts to escalate and de-escalate adjuvant systemic treatment for patients with breast cancer and argue that new, creative trial designs focused on patients' actual needs rather than on maximizing drug market size are needed. Ultimately, the adoption of effective treatments that do not needlessly expose patients and health-care systems to harm demands extensive international collaboration between academic groups, governments, and pharmaceutical companies.

Purpose: To assess the prognostic and predictive value of selected biomarkers involved in cell-cycle regulation or proliferation in patients with HER2-positive early breast cancer. Experimental Design: Protein expression of TOP2A, Ki67, cyclin D1, and p27 was immunohistochemically determined in tissue microarrays of surgical specimens from 862 patients randomized to trastuzumab (1 or 2 years; N = 561) and observation ( N = 301) arms of the HERA trial. The primary analysis endpoint was disease-free survival (DFS). Biomarkers were examined as continuous or categorical variables (predefined cutoffs). Interaction terms between biomarkers and treatment were assessed in multivariate Cox models adjusted for variables of clinical interest. Results: A significant interaction was detected between p27 and treatment (adjusted P = 0.0049). Trastuzumab effect was significant in the p27-low subgroup (≤70% p27-positive tumor cells; N = 318). HR Comb Trast vs. Obs 0.44, 95% CI, 0.29-0.65 ( P < 0.001). No trastuzumab effect was observed in the p27-high subgroup N = 435; HR Comb Trast vs. Obs 0.97, 95% CI, 0.66-1.44, P = 0.89), indicating that these patients derived little or no benefit from trastuzumab treatment. A prognostic effect of p27 on DFS was observed, with p27-high patients experiencing half the hazard of a DFS event compared with low ones (HR p27 High vs. Low 0.49, 95% CI, 0.32-0.75). TOP2A, Ki67, and cyclin D1, as categorical variables were not predictive, whereas cyclin D1 as continuous variable was predictive of trastuzumab benefit. Conclusions: In TransHERA, patients with HER2-positive early breast cancer with low p27 expression in their tumors benefited from trastuzumab treatment, whereas patients with high p27 expression did not. Clin Cancer Res; 24(13); 3079-86. ©2018 AACR ., (©2018 American Association for Cancer Research.)

Background: Biomarkers of cardiac damages, such as troponin T (TnT) and the amino-terminal fragment of brain natriuretic peptide (NT-proBNP), may be useful as early predictors of cardiac dysfunction. The role of these biomarkers in patients receiving lapatinib and/or trastuzumab before anthracyclines is unknown. This study explores TnT and NT-proBNP as predictors of early cardiac toxicity in neoadjuvant breast cancer patients., Methods: This sub-study of the NEOALTTO trial tested if changes in the levels of TnT and NT-proBNP occurred after 2 weeks of anti-HER2 therapy (lapatinib, trastuzumab or their combination) alone and/or after 18 weeks of anti-HER2 therapy plus weekly paclitaxel., Results: 173 and 172 were tested at all three timepoints for NT-proBNP and TnT, respectively. The incidence of biomarker elevation was overall low at all timepoints for all the three treatment arms. A total of 13 CEs in 11 patients occurred. Biomarker elevations in patients with CEs were very rare; only one patient with subsequent CE had a NT-proBNP elevation at baseline and at week 2., Conclusion: These results suggest that TnT and proBNP may not be useful as early predictors of cardiac toxicity in anthracycline-naïve patients receiving trastuzumab and/or lapatinib.

Purpose Phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit alpha ( PIK3CA) mutations are frequently observed in primary breast cancer. We evaluated their prognostic relevance by performing a pooled analysis of individual patient data. Patients and Methods Associations between PIK3CA status and clinicopathologic characteristics were tested by applying Cox regression models adjusted for age, tumor size, nodes, grade, estrogen receptor (ER) status, human epidermal growth factor receptor 2 (HER2) status, treatment, and study. Invasive disease-free survival (IDFS) was the primary end point; distant disease-free survival (DDFS) and overall survival (OS) were also assessed, overall and by breast cancer subtypes. Results Data from 10,319 patients from 19 studies were included (median OS follow-up, 6.9 years); 1,787 patients (17%) received chemotherapy, 4,036 (39%) received endocrine monotherapy, 3,583 (35%) received both, and 913 (9%) received none or their treatment was unknown. PIK3CA mutations occurred in 32% of patients, with significant associations with ER positivity, increasing age, lower grade, and smaller size (all P < .001). Prevalence of PIK3CA mutations was 18%, 22%, and 37% in the ER-negative/HER2-negative, HER2-positive, and ER-positive/HER2-negative subtypes, respectively. In univariable analysis, PIK3CA mutations were associated with better IDFS (HR, 0.77; 95% CI, 0.71 to 0.84; P < .001), with evidence for a stronger effect in the first years of follow-up (0 to 5 years: HR, 0.73; 95% CI, 0.66 to 0.81; P < .001; 5 to 10 years: HR, 0.82; 95% CI, 0.68 to 0.99; P = .037); > 10 years: (HR, 1.15; 95% CI, 0.84 to 1.58; P = .38; P heterogeneity = .02). In multivariable analysis, PIK3CA genotype remained significant for improved IDFS ( P = .043), but not for the DDFS and OS end points. Conclusion In this large pooled analysis, PIK3CA mutations were significantly associated with a better IDFS, DDFS, and OS, but had a lesser prognostic effect after adjustment for other prognostic factors.

Introduction: Dysregulated cellular proliferation, one of the hallmarks of cancer, is mediated by aberrant activation of the cell cycle machinery through the biological effects of cyclin-dependent kinases (CDKs). The clinical development of non-selective CDK inhibitors failed due to combined lack of efficacy and excessive toxicity reported by clinical trials across different cancer types. The clinical development of second generation, CDK4/6-selective inhibitors, namely palbociclib, abemaciclib and ribociclib, led to practice-changing results in the setting of breast cancer. Areas covered: This review illustrates how CDK4/6-selective inhibitors got approval for the treatment of patients with either newly diagnosed or pretreated advanced hormone receptor positive, HER2-negative breast cancer. Furthermore, data about potential predictive biomarkers, as well as preclinical and preliminary clinical evidence for potential antitumor activity of CDK4/6 inhibition in other breast cancer subtypes is provided. Expert opinion: Future clinical development of CDK4/6 inhibitors in breast cancer will focus on the following aspects: i) optimization of treatment sequencing for patients with advanced disease, ii) early-stage disease, iii) other subtypes of breast cancer in rationally chosen therapeutic combinations and iv) the identification of predictive biomarkers.

Aim: The Neoadjuvant PI3K inhibition in HER2 OverExpressing Breast cancEr (NeoPHOEBE) trial evaluated the efficacy and safety of buparlisib, a pan-phosphatidylinositol 3-kinase (PI3K) inhibitor, plus trastuzumab and paclitaxel as neoadjuvant treatment for human epidermal growth factor receptor-2 positive (HER2+) breast cancer., Methods: NeoPHOEBE was a neoadjuvant, phase II, randomised, double-blind study. Women with HER2+ breast cancer were randomised within two independent cohorts by PIK3CA mutation status and, in each cohort stratified by oestrogen receptor (ER) status to receive buparlisib or placebo plus trastuzumab (first 6 weeks) followed by buparlisib or placebo with trastuzumab and paclitaxel. Primary end-point was pathological complete response (pCR) rate; key secondary end-point was objective response rate (ORR) at 6 weeks. Exploratory end-points were evaluation of Ki67 levels and change in tumour infiltrating lymphocytes (TILs) in intermediate biopsies at day 15., Results: Recruitment was suspended mainly due to liver toxicity after enrolment of 50 of the planned 256 patients. In each arm (buparlisib n = 25; placebo n = 25) 21 patients (84%) had wild type PIK3CA and 4 patients (16%) had mutant PIK3CA. Overall, pCR rate was similar between buparlisib and placebo arms (32.0% versus 40%; one-sided P = 0.811). A trend towards higher ORR (68.8% versus 33.3%; P = 0.053) and a significant decrease in Ki67 (75% versus 26.7%; P = 0.021) was observed in buparlisib versus placebo arm in the ER+ subgroup (P interaction  = 0.03)., Conclusions: Addition of the pan-PI3K inhibitor buparlisib to taxane-trastuzumab-based therapy in HER2+ early breast cancer was not feasible. However, the higher ORR and Ki67 reduction in the ER+, HER2+ subgroup indicates a potential role for PI3K-targeted therapy in this setting and may warrant further investigation with better-tolerated second-generation PI3K inhibitors., Trial Registration Identifier: NCT01816594., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Estrogen receptor positive (ER+) and HER2-negative (HER2-) breast cancer (BC) is the most common BC subtype, defined by expression of the ER and absence of HER2 amplification. Endocrine treatment (ET), aiming at therapeutic blockade of ER signaling, represents the therapeutic mainstay for patients with both early and advanced disease. Despite its wide therapeutic efficacy, ET fails for a proportion of ER+, HER2- BC patients with early disease who develop endocrine resistance, resulting in disease recurrence. Endocrine resistance occurs almost invariably in patients with metastatic disease. Recently, increasing understanding of the molecular mediators of endocrine resistance has been achieved. This review focuses on the molecular mechanisms mediating endocrine resistance, on molecularly targeted agents to overcome or delay it, and potential predictive biomarkers for accurate patient stratification., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Several studies have demonstrated the feasibility of molecular screening of tumour samples for matching patients with cancer to targeted therapies. However, most of them have been carried out at institutional or national level. Herein, we report on the pilot phase of AURORA (NCT02102165), a European multinational collaborative molecular screening initiative for advanced breast cancer patients. Forty-one patients were prospectively enroled at four participating centres across Europe. Metastatic tumours were biopsied and profiled using an Ion Torrent sequencing platform at a central facility. Sequencing results were obtained for 63% of the patients in real-time with variable turnaround time stemming from delays between patient consent and biopsy. At least one clinically actionable mutation was identified in 73% of patients. We used the Illumina sequencing technology for orthogonal validation and achieved an average of 66% concordance of substitution calls per patient. Additionally, copy number aberrations inferred from the Ion Torrent sequencing were compared to single nucleotide polymorphism arrays and found to be 59% concordant on average. Although this study demonstrates that powerful next generation genomic techniques are logistically ready for international molecular screening programs in routine clinical settings, technical challenges remain to be addressed in order to ensure the accuracy and clinical utility of the genomic data.

Cancer is one of the oldest diseases ever described, since ancient Egypt there have always been attempts to treat and cure this illness. The growing body of knowledge about breast cancer biology and improvements in surgical and medical treatments has been built over time with contributions from many talented and enthusiastic physicians and researchers. Medical advances have changed the approach from a previously incurable condition, into a surgical disease. Further improvements in cancer biology have allowed the development of systemic treatments, hormonal therapies, and targeted drugs. The description of the molecular intrinsic subtypes of breast cancer clarified the understanding of breast cancer as a group of heterogeneous diseases, associated with different clinical outcomes, and therapeutic opportunities. This paper reviews how breast cancer treatment has improved since the earliest descriptions, in ancient times, and how future approaches, such as gene signatures, molecular profiling, and liquid biopsies, aim to further develop individualised treatments and improve treatment outcomes.

Purpose: Androgen receptor (AR) expression has been observed in about 70% of patients with breast cancer, but its prognostic role remains uncertain. Experimental Design: To assess the prognostic role of AR expression in early-stage breast cancer, we performed a meta-analysis of studies that evaluated the impact of AR at the protein and gene expression level on disease-free survival (DFS) and/or overall survival (OS). Eligible studies were identified by systematic review of electronic databases using the MeSH-terms "breast neoplasm" and "androgen receptor" and were selected after a qualitative assessment based on the REMARK criteria. A pooled gene expression analysis of 35 publicly available microarray data sets was also performed from patients with early-stage breast cancer with available gene expression and clinical outcome data. Results: Twenty-two of 33 eligible studies for the clinical meta-analysis, including 10,004 patients, were considered as evaluable for the current study after the qualitative assessment. AR positivity defined by IHC was associated with improved DFS in all patients with breast cancer [multivariate (M) analysis, HR 0.46; 95% confidence interval (CI) 0.37-0.58, P < 0.001] and better OS [M-HR 0.53; 95% CI, 0.38-0.73, P < 0.001]. Thirty-five datasets including 7,220 patients were eligible for the pooled gene expression analysis. High AR mRNA levels were found to confer positive prognosis overall in terms of DFS (HR 0.82; 95% CI 0.72-0.92; P = 0.0007) and OS (HR 0.84; 95% CI, 0.75-0.94; P = 0.02) only in univariate analysis. Conclusions: Our analysis, conducted among more than 17,000 women with early-stage breast cancer included in clinical and gene expression analysis, demonstrates that AR positivity is associated with favorable clinical outcome. Clin Cancer Res; 23(11); 2702-12. ©2016 AACR ., (©2016 American Association for Cancer Research.)

Background: The development of trastuzumab is considered to be one of the greatest improvements in breast cancer treatment in recent years. This study aims to evaluate changes in the uptake of trastuzumab over the last 12 years and to determine whether its use is proportional to patient needs in the European Union and the USA., Methods: Using national registry data, the number of new cases of HER2-positive breast cancer patients per year was estimated. The number of likely trastuzumab treatments per year was estimated using trastuzumab procurement data for each country., Results: Western Europe and the USA show increasing procurement level of trastuzumab over the years studied, reaching proportional of use of trastuzumab few years after its marketing authorization in the early 2000's. After the approval in the adjuvant setting, in the year 2006, it was observed underuse of trastuzumab given the increase of the number of patients in need of treatment. Proportional use was shortly met after a couple of years. Few countries in Eastern Europe acquired the needed quantity of trastuzumab, with procurement levels starting to increase only after approval in the adjuvant setting in 2006., Conclusion: Significant differences in trastuzumab procurement are observed between Western Europe, the USA and Eastern Europe, with the latter geographic region acquiring insufficient amounts of the drug required to treat all patients in need.

Purpose Women receiving trastuzumab with chemotherapy are at risk for trastuzumab-related cardiac dysfunction (TRCD). We explored the prognostic value of cardiac markers (troponins I and T, N-terminal prohormone of brain natriuretic peptide [NT-proBNP]) to predict baseline susceptibility to develop TRCD. We examined whether development of cardiac end points or significant left ventricular ejection fraction (LVEF) drop was associated with markers' increases. Patients and Methods Cardiac marker assessments were coupled with LVEF measurements at different time points for 533 patients from the Herceptin Adjuvant (HERA) study who agreed to participate in this study. Patients with missing marker assessments were excluded, resulting in 452 evaluable patients. A primary cardiac end point was defined as symptomatic congestive heart failure of New York Heart Association class III or IV, confirmed by a cardiologist, and a significant LVEF drop, or death of definite or probable cardiac causes. A secondary cardiac end point was defined as a confirmed significant asymptomatic or mildly symptomatic LVEF drop. Results Elevated baseline troponin I (> 40 ng/L) and T (> 14 ng/L), occurring in 56 of 412 (13.6%) and 101 of 407 (24.8%) patients, respectively, were associated with an increased significant LVEF drop risk (univariate analysis: hazard ratio, 4.52; P < .001 and hazard ratio, 3.57; P < .001, respectively). Few patients had their first elevated troponin value recorded during the study (six patients for troponin I and 25 patients for troponin T). Two patients developed a primary and 31 patients a secondary cardiac end point (recovery rate of 74%, 23 of 31). For NT-proBNP, higher increases from baseline were seen in patients with significant LVEF drop. Conclusion Elevated troponin I or T before trastuzumab is associated with increased risk for TRCD. A similar conclusion for NT-proBNP could not be drawn because of the lack of a well-established elevation threshold; however, higher increases from baseline were seen in patients with TRCD compared with patients without.

Introduction: The potential of molecular targeted therapy to improve the clinical outcomes of patients with early-stage breast cancer (BC) as adjuvant therapy has been first demonstrated through endocrine treatment. The introduction of HER2 blockade, through the successful clinical development of trastuzumab, changed the natural history of HER2-positive BC subtype. Areas covered: There are ongoing efforts to augment further the use of targeted agents as adjuvant treatment in BC, hoping that early introduction of targeted therapy blocking key oncogenic drivers of micro-residual disease, will significantly improve clinical outcomes. In the present Review, we present data through extensive search of PubMed about the following targeted adjuvant therapeutic strategies in BC: i) HER2 blockade and ongoing efforts to further augment its efficacy for patients with HER2-positive disease, ii) angiogenesis inhibition, iii) PI3K-mTOR- AKT pathway inhibition, iv) CDK4/6 inhibition, v) PARP inhibition. Expert commentary: we provide insights about challenges and potential ways to overcome them, in terms of successful clinical development of targeted agents as adjuvant therapy for patients with BC. In particular, we emphasize the need to systematically assess minimal residual cancer burden as a way to increase the rates of successful clinical development of targeted agents in the adjuvant setting.

Hormone receptor positive breast cancer (HR-positive BC) is the most frequent BC subtype (∼70%), with endocrine treatment constituting its therapeutic cornerstone; despite its efficacy, endocrine resistance can develop, clinically as a relapse or a progression of the early or advanced disease respectively, hence necessitating alternative treatments. Over the last two decades, improved understanding of the molecular mechanisms of endocrine resistance has been achieved, with numerous targeted agents undergoing clinical development. Despite the multifactorial genesis of endocrine resistance, fuelled not only by alternative oncogenic signaling pathways of tumor cells, but also by tumor microenvironment-mediated mechanisms, successful clinical development of new agents has been recently noted. However, predictive biomarkers for accurate 'navigation' across the different treatment options are urgently needed. In this article, we present a thorough overview of the different clinical scenarios of BC endocrine resistance, and the recent advances in endocrine treatment, we describe the basic molecular mediators of endocrine resistance and the respective targeted agents undergoing clinical development; finally, we provide our perspective on the future of BC endocrine treatment., (Copyright © 2016. Published by Elsevier Ltd.)

Background: EndoTAG-1, a tumor endothelial targeting agent has shown activity in metastatic triple-negative breast cancer (BC) in combination with paclitaxel., Methods: HER2-negative BC patients candidates for neoadjuvant chemotherapy were scheduled to receive 12 cycles of weekly EndoTAG-1 22mg/m2 plus paclitaxel 70mg/m2 followed by 3 cycles of FEC (Fluorouracil 500mg/m2, Epirubicin 100mg/m2, Cyclophosphamide 500mg/m2) every 3 weeks followed by surgery. Primary endpoint was percent (%) reduction in Magnetic Resonance Imaging (MRI) estimated Gadolinium (Gd) enhancing tumor volume at the end of EndoTAG-1 plus paclitaxel administration as compared to baseline. Safety, pathological complete response (pCR) defined as no residual tumor in breast and axillary nodes at surgery and correlation between % reduction in MRI estimated tumor volume and pCR were also evaluated., Results: Fifteen out of 20 scheduled patients were included: Six patients with estrogen receptor (ER)-negative/HER2-negative and 9 with ER-positive/HER2-negative BC. Nine patients completed treatment as per protocol. Despite premedication and slow infusion rates, grade 3 hypersensitivity reactions to EndoTAG-1 were observed during the 1st, 2nd, 3rd and 6th weekly infusion in 4 patients, respectively, and required permanent discontinuation of the EndoTAG-1. Moreover, two additional patients stopped EndoTAG-1 plus paclitaxel after 8 and 9 weeks due to clinical disease progression. Two patients had grade 3 increases in transaminases and 1 patient grade 4 neutropenia. pCR was achieved in 5 of the 6 ER-/HER2- and in none of the 9 ER+/HER2- BC patients. The mean % reduction in MRI estimated tumor volume at the end of EndoTAG-1 plus paclitaxel treatment was 81% (95% CI, 66% to 96%, p<0.001) for the 15 patients that underwent surgery; 96% for patients with pCR and 73% for patients with no pCR (p = 0.04)., Conclusions: The EndoTAG-1 and paclitaxel combination showed promising preliminary activity as preoperative treatment, especially in ER-/HER2- patients. Further studies are warranted with need of premedication optimization., Trial Registration: ClinicalTrials.gov NCT01537536.

Breast cancer is the leading cause of cancer death among women worldwide, and increasingly, randomised controlled trials of this disease are measuring the health-related quality of life of these patients. In this systematic Review, we assess the adequacy of methods used to report health-related quality of life (HRQOL) from 49 eligible randomised controlled trials of advanced breast cancer. We compare our findings with those from the literature to investigate whether the standard of HRQOL reporting in this field has changed. We conclude that the overall reporting of HRQOL has improved, but some crucial aspects remain problematic, such as the absence of HRQOL research hypotheses and the overemphasis on statistical rather than clinical significance. Additionally, new challenges are arising with the emergence of novel treatments and the advent of personalised medicine, and improved HRQOL tools are required to cover the range of side-effects of newer therapies., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The implementation of molecular profiling technologies in oncology deepens our knowledge for the molecular landscapes of cancer diagnoses, identifying aberrations that could be linked with specific therapeutic vulnerabilities. In particular, there is an increasing list of molecularly targeted anticancer agents undergoing clinical development that aim to block specific molecular aberrations. This leads to a paradigm shift, with an increasing list of specific aberrations dictating the treatment of patients with cancer. This paradigm shift impacts the field of clinical trials, since the classical approach of having clinico-pathological disease characteristics dictating the patients' enrolment in oncology trials shifts towards the implementation of molecular profiling as pre-screening step. In order to facilitate the successful clinical development of these new anticancer drugs within specific molecular niches of cancer diagnoses, there have been developed new, innovative trial designs that could be classified as follows: i) longitudinal cohort studies that implement (or not) "nested" downstream trials, 2) studies that assess the clinical utility of molecular profiling, 3) "master" protocol trials, iv) "basket" trials, v) trials following an adaptive design. In the present article, we review these innovative study designs, providing representative examples from each category and we discuss the challenges that still need to be addressed in this era of new generation oncology trials implementing molecular profiling. Emphasis is put on the field of breast cancer clinical trials.

The introduction of trastuzumab as adjuvant treatment for patients with HER2-positive breast cancer changed the natural course of early-stage disease. Currently, one year of trastuzumab given concurrently with a taxane and following an anthracycline regimen is the preferred standard of care in Europe. The first attempt to escalate this approach, though the implementation of dual HER2 blockade with lapatinib added to trastuzumab, as assessed by the ALTTO trial, failed to improve further clinical outcomes; clinical assessment of the adjuvant trastuzumab/pertuzumab regimen is still ongoing in the APHINITY trial. Negative results were also reported for the addition of bevacizumab to adjuvant trastuzumab treatment within the context of the BETH study. Similarly, efforts to de-escalate through shortening the duration of adjuvant trastuzumab treatment failed (the PHARE trial), whereas others are still ongoing. Of note, evidence supports the use of lighter chemotherapy regimens with one year of adjuvant trastuzumab as backbone, for women with small HER2-positive breast tumors, where the omission of anthracyclines did not compromise the clinical outcome. Despite the successes achieved so far, a proportion of women with early-stage HER2-positive breast cancer, will still experience disease recurrence. The identification of these women is urgently needed, as well as the identification of predictive biomarkers to dictate the optimal treatment strategy. So far, HER2 expression status has been the only validated predictive biomarker for this patient population. Despite the clear association of pCR achieved through neoadjuvant trastuzumab-based chemotherapy with clinical outcome, results from neoadjuvant trials have not been always consistent with what was seen in the adjuvant setting. Similarly, inconsistent results have been reported for the predictive ability of alterations affecting the PI3K signaling pathway or the quantification of tumor infiltrating lymphocytes. In the era of personalized oncology, rigorous translational and clinical collaborative efforts are needed to further advance the field of treatment of patients with HER2-positive breast cancer., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Purpose: We compared efficacy of trastuzumab versus no trastuzumab in patients with small (≤ 2 cm) human epidermal growth factor receptor 2 (HER2) -positive breast cancer treated in randomized trials., Methods: A meta-analysis was conducted using data from five of the six adjuvant trastuzumab trials. Efficacy end points were disease-free survival (DFS) and overall survival (OS). Separate analyses were prospectively planned for hormone receptor (HR) -positive and HR-negative cohorts. Random effect models and Yusuf-Peto fixed effects models assessed the impact of heterogeneity on baseline hazards and treatment effects across studies. Peto-Pike cumulative incidence estimates were stratified by study and nodal status., Results: Median follow-up time was 8 years. For 2,263 patients with HR-positive disease, 8-year cumulative incidence rates comparing trastuzumab versus no trastuzumab were 17.3% versus 24.3% (P < .001) for DFS and 7.8% versus 11.6% (P = .005) for OS, respectively; for 1,092 HR-positive patients with zero or one positive lymph nodes, results were 12.7% versus 19.4% (P = .005) for DFS and 5.3% versus 7.4% (P = .12) for OS, respectively. For 1,957 patients with HR-negative disease, 8-year cumulative incidence rates were 24.0% versus 33.4% (P < .001) for DFS and 12.4% versus 21.2% (P < .001) for OS, respectively; for 1,040 HR-negative patients with zero or one positive lymph nodes, results were 20.4% versus 26.3% (P = .05) for DFS and 8.2% versus 12.2% (P = .084) for OS, respectively., Conclusion: Women with HER2-positive tumors ≤ 2 cm in the randomized trastuzumab trials derived substantial DFS and OS benefit from adjuvant trastuzumab. Trastuzumab-treated patients with HR-positive disease and ≤ one positive lymph node may be candidates for trials assessing less aggressive treatment approaches., (© 2015 by American Society of Clinical Oncology.)

Traditionally, intertumour heterogeneity in breast cancer has been documented in terms of different histological subtypes, treatment sensitivity profiles, and clinical outcomes among different patients. Results of high-throughput molecular profiling studies have subsequently revealed the true extent of this heterogeneity. Further complicating this scenario, the heterogeneous expression of the oestrogen receptor (ER), progesterone receptor (PR), and HER2 has been reported in different areas of the same tumour. Furthermore, discordance, in terms of ER, PR and HER2 expression, has also been reported between primary tumours and their matched metastatic lesions. High-throughput molecular profiling studies have confirmed that spatial and temporal intratumour heterogeneity of breast cancers exist at a level beyond common expectations. We describe the different levels of tumour heterogeneity, and discuss the strategies that can be adopted by clinicians to tackle treatment response and resistance issues associated with such heterogeneity, including a rationally selected combination of agents that target driver mutations, the targeting of deleterious passenger mutations, identifying and eradicating the 'lethal' clone, targeting the tumour microenvironment, or using adaptive treatments and immunotherapy. The identification of the most-appropriate strategies and their implementation in the clinic will prove highly challenging and necessitate the adoption of radically new practices for the optimal clinical management of breast malignancies.

High-throughput technologies of molecular profiling in cancer, such as gene-expression profiling and next-generation sequencing, are expanding our knowledge of the molecular landscapes of several cancer types. This increasing knowledge coupled with the development of several molecularly targeted agents hold the promise for personalized cancer medicine to be fully realized. Moreover, an expanding armamentarium of targeted agents has been approved for the treatment of specific molecular cancer subgroups in different diagnoses. According to this paradigm, treatment selection should be dictated by the specific molecular aberrations found in each patient's tumor. The classical clinical trials paradigm of patients' eligibility being based on clinicopathologic parameters is being abandoned, with current clinical trials enrolling patients on the basis of specific molecular aberrations. New, innovative trial designs have been generated to better tackle the multiple challenges induced by the increasing molecular fragmentation of cancer, namely: (1) longitudinal cohort studies with or without downstream trials, (2) studies assessing the clinical utility of molecular profiling, (3) master or umbrella trials, (4) basket trials, (5) N-of-1 trials, and (6) adaptive design trials. This article provides an overview of the challenges for clinical trials in the era of molecular profiling of cancer. Subsequently, innovative trial designs with respective examples and their potential to expedite efficient clinical development of targeted anticancer agents is discussed.

Neoadjuvant treatment of breast cancer refers to the use of different treatment modalities prior to surgical excision of the tumor. It has been accepted as a treatment option for patients with nonmetastatic disease, because it renders inoperable tumors operable and increases the rates of breast-conserving surgery, while achieving similar long-term clinical outcomes as adjuvant treatment. The neoadjuvant setting is being increasingly perceived as a research platform, where the biologic effects of traditional anticancer agents can be delineated, prognostic and predictive biomarkers can be identified, and the development of targeted agents can be expedited. Surrogate endpoints that can predict long-term clinical outcome and are evaluable early on, such as the pathologic complete response, offer valuable opportunities for rapid assessment of anticancer agents. Additionally, efforts for molecular profiling of the post-neoadjuvant residual disease hold the potential to lead to personalized therapy for breast cancer patients with early-stage high-risk disease.

Background: The European Union (EU) has adopted a common procedure for granting marketing authorisation for cancer drugs. Nevertheless, pricing and reimbursement decisions are a competency of EU national governments, and their policies are diverse. We aimed to evaluate the time for trastuzumab reimbursement approval and its association to health expenditure, to health policy performance, to the availability of cost-effectiveness studies and to breast cancer outcome., Methods: Breast cancer outcome was estimated by the mortality/incidence (M/I) ratio. Trastuzumab reimbursement approval dates were provided by Roche. Spearman's rank correlation and Wilcoxon rank-sum test were used to evaluate associations and/or differences between the variables studied. Additional analyses were made by grouping countries according to compliance to the 180 day timeframe stipulated in the EU 89/105/EEC Directive for drug pricing and reimbursement., Results: A statistically significant inverse and strong correlation between breast cancer M/I ratio and health expenditure (r(s)=-0.730, p<0.001) and health policy performance (r(s)=-0.711, p<0.001) was found, meaning the better the score and the higher the expenditure, the fewer patients died after a breast cancer diagnosis. Factors associated with trastuzumab faster reimbursement and compliance to the 89/105/EEC Directive were better health policy score, higher health expenditure and availability of cost-effectiveness studies., Conclusion: Higher health policy scores and health expenditure are associated with faster reimbursement of trastuzumab and better breast cancer outcome. Although the study design does not allow inference of causal associations, a marked difference is observed between Eastern and Western Europe, with long delays and increased breast cancer mortality identified in Eastern European countries., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Gene expression profiling has reshaped our understanding of breast cancer by defining and characterizing four main intrinsic molecular subtypes: human epidermal growth factor receptor 2-enriched, basal-like, luminal A, and luminal B subtypes. Luminal B breast cancer has been reported to have lower expression of hormone receptors, higher expression of proliferation markers, and higher histologic grade than luminal A. It also exhibits worse prognosis and has a distinct profile of response to hormone therapy and chemotherapy. Although luminal cancers share similarities, the studies conducted in recent years using next-generation sequencing technology show that luminal A and B breast cancers should be perceived as distinct entities, with specific oncogenic drivers, rather than more proliferative varieties of luminal tumors. This review discusses the definition and molecular characterization of luminal B breast cancer and presents the available clinical evidence for chemotherapy and endocrine therapy patterns of response. It also provides an overview of ongoing research on molecularly targeted agents for this disease., (© 2014 by American Society of Clinical Oncology.)

Several breast cancer therapies can lead to cardiovascular toxicity: drugs such anthracyclines can cause permanent damage, anti-HER2 agents may cause transitory and reversible cardiac dysfunction and others, such as those used in endocrine therapy, primarily disturb lipid metabolism. Considering the seriousness of these complications, trials are now being conducted to address cardiotoxicity associated with new drugs; however, to fully understand their toxicity profiles, longer follow-up is needed. In this review, we compile the information available about cardiac toxicity related to well-established systemic breast cancer treatments, as well as newer drugs, including antiangiogenics, mTOR inhibitors and novel anti-HER2 agents. We also describe current and next generation cardiac biomarkers and functional tests that can optimize treatment and reduce and prevent the incidence of treatment-related cardiotoxicity., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

PIK3CA mutations represent one of the most common genetic aberrations in breast cancer. They have been reported to be present in over one-third of cases, with enrichment in the luminal and in human epidermal growth factor receptor 2-positive subtypes. Substantial preclinical data on the oncogenic properties of these mutations have been reported. However, whilst the preclinical data have clearly shown an association with robust activation of the pathway and resistance to common therapies used in breast cancer, the clinical data reported up to now do not support that the PIK3CA mutated genotype is associated with high levels of pathway activation or with a poor prognosis. We speculate that this may be due to the minimal use of transgenic mice models thus far. In this review, we discuss both the preclinical and clinical data associated with PIK3CA mutations and their potential implications. Prospective clinical trials stratifying by PIK3CA genotype will be necessary to determine if the mutation also predicts for increased sensitivity to agents targeting the phosphoinositide 3-kinase pathway.

Trastuzumab, a humanized anti-HER2 monoclonal antibody targeting the extracellular domain of this oncoprotein, represents the archetype of HER2 blocking agents. Its unprecedented efficacy for HER2-positive metastatic breast cancer (BC) led to its clinical development in the adjuvant setting. The HERceptin Adjuvant (HERA) is one of the pivotal adjuvant trastuzumab trials which proved that this compound can change the natural course of early stage HER2-positive BC. The HERA study led to the registration of trastuzumab for the adjuvant treatment of early HER2-positive BC. This trial randomized more than 5000 patients between 1 and 2 years of trastuzumab and observation after the completion of locoregional therapy and (neo)-adjuvant chemotherapy. Additionally, an abundance of subsequent substudies were conducted, addressing important clinical issues for this patient population. The present review article presents a comprehensive overview of the HERA study and its major contributions to the adjuvant treatment of HER2-positive BC patients. Emphasis is given on the lessons learned from this international collaborative experience and how this can be used as a stepping stone for further improvements in the field.

Breast cancer oncology represents one of the disciplines where personalized cancer medicine has been most actively pursued. The class-discovery studies conceptually advanced the field, underlining the molecular heterogeneity governing this common disease. The advent of high-throughput molecular profiling technologies holds great promise for the advance of all aspects of personalized cancer medicine, namely accurate prognostication, prediction of response to common systemic therapies and individualized monitoring of the disease. Moreover, an ever-expanding arsenal of targeted therapeutic compounds under clinical development, coupled with emerging powerful tools for comprehensive molecular and functional characterization, pose significant promise for improved clinical outcomes for breast cancer patients. Interrogation of the germline genetic variation offers further promise towards tailoring of breast cancer management. Well-conducted prospective validation studies are needed if breast cancer personalized therapy is to transform from a dream into a reality.

Extensive preclinical experimentation has conceptually changed the way we perceive breast cancer, with the wide spectrum of genomic alterations governing its malignant progression now being recognized. Functional genomics has helped us identify important genetic defects that can be pharmaceutically targeted in the setting of metastatic disease. Rationally chosen combination regimens are now under clinical investigation. Recent data underline the functional importance of the tumour-associated stroma, with several candidate molecular targets now emerging. Data elucidating a cellular hierarchy within the breast cancer cellular compartment support the existence of a therapy-resistant subpopulation of breast cancer stem cells. Identification of the developmental pathways that dictate their malignant phenotype and use of high-throughput screening techniques are leading to new therapeutic avenues. In this Review, we present the biological rationale for the clinical development of more than 15 different classes of targeted agents in breast cancer, along with evidence supporting rational combinations. However, metastatic breast cancer resembles a Darwinian evolutionary system, with 'driver' mutations and epigenetic changes determining clonal selection according to branching trajectories. This evolution is reflected in the molecular heterogeneity of the disease and poses severe impediments to the successful clinical development of emerging targeted agents.

HER2-positive breast cancer (BC) constitutes a molecular subtype of the disease with an aggressive biologic behavior. Trastuzumab revolutionized the treatment of this disease, changing its natural history. Lapatinib is active in the metastatic setting, approved for patients who were pretreated with trastuzumab. However, resistance to anti-HER2 agents is a major clinical issue, occurring in both early-stage and advanced disease, and new treatment options are clearly needed. An abundance of HER2-targeted agents are being clinically developed: monoclonal antibodies, small molecule inhibitors, and antibody drug conjugates (ADC). Combining HER2-targeted agents in regimens of dual HER2 blockade has already reached clinical practice in the metastatic setting, confirming the preclinical efficacy of enhanced HER2 inhibition. Promising results have been generated in the neoadjuvant setting, and large randomized trials are seeking evidence for dual HER2 blockade in the adjuvant setting. ADC represent another hope for improved treatment outcomes of HER2-positive BC, as exemplified by the positive results of clinical trials employing trastuzumab-DM1 (trastuzumab emtansine, T-DM1). Moreover, an understanding of the molecular mechanisms mediating resistance to HER2 blockade has opened new therapeutic avenues, with several targeted agents entering clinical trials. This paper presents the clinical data of the HER2-targeted agents under development, as well as an overview of the biologic rationale for the development of agents aimed at circumventing anti-HER2 resistance.

Purpose of Review: Recent data from clinical trials evaluating mammalian target of rapamycin (mTOR) inhibitors in the setting of endocrine resistance in luminal (estrogen receptor-positive, human epidermal growth factor receptor 2-negative) breast cancers have validated this pathway as a bona-fide therapeutic target in this setting. There are currently many agents under clinical investigation that inhibit the phosphatidylinositol 3-kinase (PI3K) pathway. We review these findings in the context of the preclinical data and the current status of biomarker development in this field., Recent Findings: Clinical trials in the neoadjuvant (RAD2222) and metastatic setting (TAMRAD, BOLERO-2) have reported improved clinical outcome of patients with unselected luminal breast cancer through the addition of mTOR inhibitors to standard endocrine treatment. PI3K molecular aberrations are frequently found in luminal breast cancer, yet the role of these in defining patients' prognosis and response to PI3K/AKT/mTOR inhibitors remains to be determined., Summary: Therapeutic targeting of the PI3K pathway promises improved clinical outcome for patients with luminal breast cancer. Correspondingly, agents that target this pathway are entering the clinic at an unprecedented rate. Future clinical trials that incorporate correlative translational research will help us decipher important information critical for successful development of these agents in breast cancer: which part of the pathway should be targeted and in which clinical scenario; and which patients are more likely to benefit from these drugs, particularly in the adjuvant setting.

We report unexpectedly high efficacy of temsirolimus as third-line treatment in a patient with metastatic chromophobe renal cell carcinoma. After failure of two sequentially administered tyrosine kinase inhibitors, treatment with temsirolimus resulted in a prolonged partial remission of 14 months, and the response is still continuing. Up to now, no data from randomized clinical studies have been published addressing the question of efficacy of temsirolimus as third-line treatment after failure of tyrosine kinase inhibitors. The case presented here implies that temsirolimus could be a viable option for patients with metastatic chromophobe renal cell carcinoma.