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Introduction The combination of a CDK4/6 inhibitor with an aromatase inhibitor (AI) has recently become the gold standard for AI-sensitive first line treatment of oestrogen receptor-positive (ER+) HER2-negative (HER2−) advanced breast cancer. However, most patients receiving this combination will ultimately progress and require further therapies.Several studies have demonstrated that the onset of a ESR1 gene mutation lead to AIs resistance in the advanced setting. ESR1 mutations can be detected in circulating tumour DNA (ctDNA) using a digital PCR assay. Our study aims to prove the clinical efficacy of periodic monitoring for emerging or rise of ESR1 mutations in ctDNA to trigger an early change from AI plus palbociclib to fulvestrant plus palbociclib treatment while assessing global safety.Methods PADA-1 is a randomised, open-label, multicentric, phase III trial conducted in patients receiving AI and palbociclib as first line therapy for metastatic ER +HER2- breast cancer. 1000 patients will be included and treated with palbociclib in combination with an AI. Patients will be screened for circulating blood ESR1 mutation detection at regular intervals. Patients for whom a rising circulating ESR1 mutation is detected without tumour progression (up to N=200) will be randomised (1:1) between (1) Arm A: no modification of therapy; and (2) Arm B: palbociclib in combination with fulvestrant, a selective ER down-regulator. At tumour progression, an optional crossover will be offered to patients randomised in arm A. The coprimary endpoints are (1) Grade ≥3 haematological toxicities and their associations with baseline characteristics and (2) progression-free survival in randomised patients.Ethics and dissemination The study has been approved by the French medicines agency (ANSM) and by an ethics committee (ref 01/17_1 CPP Ouest-IV Nantes) in January 2017. The trial results will be published in academic conference presentations and international peer-reviewed journals.Trial registration numbers EudraCT: 2016-004360-18; NCT03079011.

Abstract Medullary carcinoma of the breast (MedBC) is a rare histological type that accounts for less than 5% of all invasive breast cancers. Here, we performed an exploratory study aimed to determine whether imaging mass cytometry (IMC) can be used to characterize the immune infiltration and the spatial distribution heterogeneity in the rare subtype of MedBC compared to atypical MedBC and TNBC-TILS+ tumors. In both MedBC and TNBC-TILs+, there was a notable enrichment of immune cells in the peripheral regions of the tumors, whereas in atypical MedBC, the immune cells exhibited a central enrichment pattern. This distribution of infiltrated cells reflects an active immune recruitment correlated to more favorable prognosis. In MedBC, spatial analysis shows that immune cells are localized at a greater distance from the tumor cells. IMC highlights the heterogeneity of immune microenvironment across three main subtypes of breast tumors and could help to define distinct immune patterns.

Background: We aimed to generate a model of cancer-related fatigue (CRF) of clinical importance 2 years after diagnosis of breast cancer building on clinical and behavioral factors and integrating pre-treatment markers of systemic inflammation., Patients and Methods: Women with stage I-III hormone receptor-positive/human epidermal growth factor receptor 2-negative breast cancer were included from the multimodal, prospective CANTO cohort (NCT01993498). The primary outcome was global CRF of clinical importance [European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ)-C30 ≥40/100] 2 years after diagnosis (year 2). Secondary outcomes included physical, emotional, and cognitive CRF (EORTC QLQ-FA12). All pre-treatment candidate variables were assessed at diagnosis, including inflammatory markers [interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, interferon γ, IL-1 receptor antagonist, tumor necrosis factor-α, and C-reactive protein], and were tested in multivariable logistic regression models implementing multiple imputation and validation by 100-fold bootstrap resampling., Results: Among 1208 patients, 415 (34.4%) reported global CRF of clinical importance at year 2. High pre-treatment levels of IL-6 (quartile 4 versus 1) were associated with global CRF at year 2 [adjusted odds ratio (aOR): 2.06 (95% confidence interval [CI] 1.40-3.03); P = 0.0002; area under the receiver operating characteristic curve = 0.74]. Patients with high pre-treatment IL-6 had unhealthier behaviors, including being frequently either overweight or obese [62.4%; mean body mass index 28.0 (standard deviation 6.3 kg/m 2 )] and physically inactive (53.5% did not meet World Health Organization recommendations). Clinical and behavioral associations with CRF at year 2 included pre-treatment CRF [aOR versus no pre-treatment CRF: 3.99 (95% CI 2.81-5.66)], younger age [aOR per 1-year decrement: 1.02 (95% CI 1.01-1.03)], current tobacco smoking [aOR versus never: 1.81 (95% CI 1.26-2.58)], and worse insomnia or pain [aOR per 10-unit increment: 1.08 (95% CI 1.04-1.13), and 1.12 (95% CI 1.04-1.21), respectively]. Secondary analyses indicated additional associations of IL-2 [aOR per log-unit increment: 1.32 (95% CI 1.03-1.70)] and IL-10 [0.73 (95% CI 0.57-0.93)] with global CRF and of C-reactive protein [1.42 (95% CI 1.13-1.78)] with cognitive CRF at year 2. Emotional distress was consistently associated with physical, emotional, and cognitive CRF., Conclusions: This study proposes a bio-behavioral framework linking pre-treatment systemic inflammation with CRF of clinical importance 2 years later among a large prospective sample of survivors of breast cancer., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Inflammatory breast cancer (IBC) is the most aggressive clinical presentation of breast cancer, recapitulating a specific biology with more immune-vulnerability than non-IBC. Patients with metastatic, triple-negative IBC (mTN-IBC) receive immune checkpoint inhibitors (ICIs) and chemotherapy, similarly to patients with triple-negative non-IBC. However, the benefit derived from ICI incorporation in this rare type of breast cancer is unknown., Methods: We conducted a multicenter, international, retrospective, cohort study to evaluate the activity of ICIs in patients with metastatic, triple-negative, primary IBC, who received ICIs plus first line chemotherapy from January 2015 to April 2023. A sample size of 42 patients allowed to detect an increase in 6-months real-world progression-free survival (rwPFS) rate from 40 % with only chemotherapy to 60 % with ICI and chemotherapy., Results: 41 patients from eight international IBC referral centers were included (61 % with primary, de novo mTN-IBC, 61 % with visceral disease). All received ICIs plus first line chemotherapy and 24 % underwent breast surgery and/or locoregional radiotherapy. After a median follow-up of 19.3 months, the 6-months rwPFS rate was 30 % (95 % Confidence Interval [CI], 17-45 %), the median rwPFS was 3.3 months (95 % CI: 2.2-5.4), the median overall survival was 15.7 months (95 % CI: 6.8-16.3)., Conclusions: This one-sample analysis showed a poor outcome of patients with mTN-IBC, despite the treatment with ICI, in contrast with the expected benefit based on preclinical evidence of immune-vulnerability of IBC. These results suggest the need to further investigate the role of immunotherapy in this aggressive and rare type of breast cancer presentation., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. GC reports financial interests with AstraZeneca, Celcuity, Daiichi Sankyo, Exact Sciences, Lilly, Merck, Novartis, Pfizer, Roche, Veracyte, Ellipsis, Astellas, Blueprint Medicine, BMS, Kymab, Merck, Novartis, Philogen, Relay Therapeutics, Sanofi; and non-financial interests with the Italian National Health Council as Advisor for Ministry of Health ESMO, ESMO as Clinical Practice Guidelines Chair, Europa Donna as Member of the Scientific Council, EUSOMA as member of the Advisory Council, Fondazione Beretta, Lega Italiana Lotta ai Tumori as member of Board of Directors. RML received research support to her institution from Celcuity, Eli Lilly, Novartis, Pfizer, Arvinas, Puma, Zentalis, and Accutar Biotechnology; participated in advisory boards/consulting work for Celcuity, Eli Lilly, Novartis, Biotheryx, and Gilead; received honorarium from Pfizer. All the competing interests were outside the submitted work. All other authors have no potential conflict of interest to disclose related to the submitted work., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Purpose: Long-term treatment-related toxicities, such as neurologic and metabolic toxicities, are major issues in breast cancer. We investigated the interest of metabolomic profiling to predict toxicities., Experimental Design: Untargeted high-resolution metabolomic profiles of 992 patients with estrogen receptor (ER)+/HER2- breast cancer from the prospective CANTO cohort were acquired (n = 1935 metabolites). A residual-based modeling strategy with discovery and validation cohorts was used to benchmark machine learning algorithms, taking into account confounding variables., Results: Adaptive Least Absolute Shrinkage and Selection (adaptive LASSO) has a good predictive performance, has limited optimism bias, and allows the selection of metabolites of interest for future translational research. The addition of low-frequency metabolites and nonannotated metabolites increases the predictive power. Metabolomics adds extra performance to clinical variables to predict various neurologic and metabolic toxicity profiles., Conclusions: Untargeted high-resolution metabolomics allows better toxicity prediction by considering environmental exposure, metabolites linked to microbiota, and low-frequency metabolites., (©2024 American Association for Cancer Research.)

Medullary carcinoma of the breast (MedBC) is a rare histological type that accounts for less than 5% of all invasive breast cancers. Here, we performed an exploratory study aimed to determine whether imaging mass cytometry (IMC) can be used to characterize the immune infiltration and the spatial distribution heterogeneity in the rare subtype of MedBC compared to atypical MedBC and TNBC-TILS + tumors. In both MedBC and TNBC-TILs + , there was a notable enrichment of immune cells in the peripheral regions of the tumors, whereas in atypical MedBC, the immune cells exhibited a central enrichment pattern. This distribution of infiltrated cells reflects an active immune recruitment correlated to more favorable prognosis. In MedBC, spatial analysis shows that immune cells are localized at a greater distance from the tumor cells. IMC highlights the heterogeneity of immune microenvironment across three main subtypes of breast tumors and could help to define distinct immune patterns., (© 2024. The Author(s).)

Purpose: The global, phase 3, open-label, randomized TROPION-Breast01 study assessed the trophoblast cell surface antigen 2-directed antibody-drug conjugate datopotamab deruxtecan (Dato-DXd) versus investigator's choice of chemotherapy (ICC) in hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer., Methods: Adult patients with inoperable/metastatic HR+/HER2‒ breast cancer, who had disease progression on endocrine therapy, for whom endocrine therapy was unsuitable, and had received one to two previous lines of chemotherapy in the inoperable/metastatic setting, were randomly assigned 1:1 to Dato-DXd (6 mg/kg once every 3 weeks) or ICC (eribulin/vinorelbine/capecitabine/gemcitabine). Dual primary end points were progression-free survival (PFS) by blinded independent central review (BICR) and overall survival (OS)., Results: Patients were randomly assigned to Dato-DXd (n = 365) or ICC (n = 367). Dato-DXd significantly reduced the risk of progression or death versus ICC (PFS by BICR hazard ratio [HR], 0.63 [95% CI, 0.52 to 0.76]; P < .0001). Consistent PFS benefit was observed across subgroups. Although OS data were not mature, a trend favoring Dato-DXd was observed (HR, 0.84 [95% CI, 0.62 to 1.14]). The rate of grade ≥3 treatment-related adverse events (TRAEs) with Dato-DXd was lower than ICC (20.8% v 44.7%). The most common TRAEs (any grade; grade ≥3) were nausea (51.1%; 1.4%) and stomatitis (50%; 6.4%) with Dato-DXd and neutropenia (grouped term, 42.5%; 30.8%) with ICC., Conclusion: Patients receiving Dato-DXd had statistically significant and clinically meaningful improvement in PFS and a favorable and manageable safety profile, compared with ICC. Results support Dato-DXd as a novel treatment option for patients with inoperable/metastatic HR+/HER2‒ breast cancer who have received one to two previous lines of chemotherapy in this setting.

Background: Fatigue, cognitive impairment, anxiety, depression, and sleep disturbance are cancer-related behavioral symptoms (CRBS) that may persist years after early-stage breast cancer (BC), affecting quality of life. We aimed at generating a predictive model of long-term CRBS clusters among BC survivors four years post-diagnosis., Methods: Patients with early-stage BC were included from the CANcer TOxicity (NCT01993498). Our outcome was the proportion of patients reporting CRBS clusters four years post-diagnosis (≥3 severe CRBS). Predictors, including clinical, behavioral, and treatment-related characteristics, Behavioral Symptoms Score (BSS; 1 point per severe CRBS at diagnosis) and a pro-inflammatory cytokine (IL-1b, IL-6, TNFα)-genetic risk score, were tested using multivariable logistic regression, implementing bootstrapped Augmented Backwards Elimination. A two-sided p-value < 0.05 defined statistical significance., Results: In the development cohort (N = 3555), 642 patients (19.0%) reported a cluster of CRBS at diagnosis and 755 (21.2%) did so four years post-diagnosis. Younger age (adjusted Odds Ratio [aOR] for 1-year decrement: 1.012; 95% Confidence Interval [CI] 1.003-1.020); previous psychiatric disorders (aOR vs no: 1.27; 95% CI 1.01-1.60); and BSS (aOR ranged from 2.17 [1.66-2.85] for BSS = 1 vs 0 to 12.3 [7.33-20.87] for BSS = 5 vs 0) were predictors of reporting a cluster of CRBS (AUC 0.73 [95%CI 0.71-0.75]). Genetic risk score was not predictive of CRBS. Results were confirmed in the validation cohort (N = 1533)., Conclusion: Younger patients with previous psychiatric disorders and higher baseline symptom burden have greater risk of long-term clusters of CRBS. Our model might be implemented in clinical pathways to improve management and test the effectiveness of risk mitigation interventions among breast cancer survivors., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

For patients with hormone receptor-positive/human epidermal growth factor receptor 2 (HER2)-negative (HR+/HER2-) metastatic breast cancer (mBC) progressed on first-line endocrine therapy plus a cyclin-dependent kinase 4 and 6 inhibitor (CDK4/6i), fulvestrant, a selective estrogen receptor degrader (SERD) administered intramuscularly, represented the only monotherapy option until the approval of elacestrant. This oral SERD has been approved for patients with ESR1-mutant HR+/HER2- mBC by the European Medicines Agency, the Food and Drug Administration, and the UK Medicines and Healthcare products Regulatory Agency, according to the results of the randomized phase III EMERALD trial, which demonstrated elacestrant superiority over standard endocrine monotherapy. Consequently, elacestrant has been incorporated in the European Society for Medical Oncology and American Society of Clinical Oncology guidelines. However, in Europe, the access to this recommended drug depends on the decision of the National Health Authorities of each state. In this communication, we describe the main results and implications of the EMERALD trial, in the context of the biomarker-driven algorithm for patients with HR+/HER2- mBC progressed on CDK4/6i, and conclude that a subgroup of patients with ESR1-mutant tumors and specific clinical features can really derive a clinically meaningful benefit from elacestrant, sparing access to more toxic combination approaches and preserving the quality of life., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Purpose: Postdiagnosis exercise is associated with lower breast cancer (BC) mortality but its link with risk of recurrence is less clear. We investigated the impact and dose-response relationship of exercise and recurrence in patients with primary BC., Methods: Multicenter prospective cohort analysis among 10,359 patients with primary BC from 26 centers in France between 2012 and 2018 enrolled in the CANcer TOxicities study, with follow-up through October 2021. Exercise exposure was assessed using the Global Physical Activity Questionnaire-16, quantified in standardized metabolic equivalent of task-hours per week (MET-h/wk). We examined the dose/exposure response of pretreatment exercise on distant recurrence-free interval (DRFI) for all patients and stratified by clinical subtype and menopausal status using inverse probability treatment weighted multivariable Cox models to estimate hazard ratios (HRs)., Results: For the overall cohort, the relationship between exercise and DRFI was nonlinear: increasing exercise ≥ 5 MET-h/wk was associated with an inverse linear reduction in DRFI events up to approximately 25 MET-h/wk; increasing exercise over this threshold did not provide any additional DRFI benefit. Compared with <5 MET-h/wk, the adjusted HR for DRFI was 0.82 (95% CI, 0.61 to 1.00) for ≥ 5 MET-h/wk. Stratification by subtype revealed the hormone receptor-/human epidermal growth factor receptor 2- (HR-/HER2-; HR, 0.59 [95% CI, 0.38 to 0.92]) and HR-/HER2+ (HR, 0.37 [95% CI, 0.14 to 0.96]) subtypes were preferentially responsive to exercise. The benefit of exercise was observed especially in the premenopausal population., Conclusion: Postdiagnosis/pretreatment exercise is associated with lower risk of DRFI events in a nonlinear fashion in primary BC; exercise has different impact on DRFI as a function of subtype and menopausal status.

Breast cancer is a heterogeneous disease, encompassing multiple different subtypes. Thanks to the increasing knowledge of the diverse biological features of each subtype, most patients receive personalized treatment based on known biomarkers. However, the role of some biomarkers in breast cancer evolution is still unknown, and their potential use as a therapeutic target is still underexplored. HER3 is a member of the human epidermal growth factors receptor family, overexpressed in 50%-70% of breast cancers. HER3 plays a key role in cancer progression, metastasis development, and drug resistance across all the breast cancer subtypes. Owing to its critical role in cancer progression, many HER3-targeting therapies have been developed over the past decade with conflicting findings. Next-generation antibody-drug conjugates have recently shown promising results in solid tumors expressing HER3, including breast cancer. In this review, we discuss the HER3 role in the pathogenesis of breast cancer and its relevance across all subtypes. We also explore the new anti-HER3 treatment strategies, calling into question the significance of HER3 detection as crucial information in breast cancer treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Breast cancer is the most frequently diagnosed cancer in women worldwide, and non-adherence to adjuvant hormonotherapy can negatively impact cancer recurrence and relapse. Non-adherence is associated with side effects of hormonotherapy. Pharmacological strategies to mitigate the side effects include coadministration of antidepressants, however patients remain non-adherent. The aim of this work was to develop medicines containing both hormonotherapy, tamoxifen (20 mg), along with anti-depressants, either venlafaxine (37.5 or 75 mg) or duloxetine (30 or 60 mg), to assess the acceptability and efficacy of this personalised approach for mitigating tamoxifen side effects in a clinical trial. A major criterion for the developed medicines was the production rate, specified at minimum 200 dosage units per hour to produce more than 40,000 units required for the clinical trial. A novel capsule filling approach enabled by the pharmaceutical 3D printer M3DIMAKER 2 was developed for this purpose. Firstly, semi-solid extrusion 3D printing enabled the filling of tamoxifen pharma-ink prepared according to French compounding regulation, followed by filling of commercial venlafaxine or duloxetine pellets enabled by the development of an innovative pellet dispensing printhead. The medicines were successfully developed and produced in the clinical pharmacy department of the cancer hospital Gustave Roussy, located in Paris, France. The developed medicines satisfied quality and production rate requirements and were stable for storage up to one year to cover the duration of the trial. This work demonstrates the feasibility of developing and producing combined tamoxifen medicines in a hospital setting through a pharmaceutical 3D printer to enable a clinical trial with a high medicines production rate requirement., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Abdul W. Basit reports a relationship with FABRX Ltd. that includes: employment and equity or stocks. Alvaro Goyanes reports a relationship with FABRX Ltd. that includes: employment and equity or stocks. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.]., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Importance: Return to work after breast cancer (BC) treatment depends on several factors, including treatment-related adverse effects. While cancer-related cognitive impairment is frequently reported by patients with BC, to date, no longitudinal studies have assessed its association with return to work., Objective: To examine whether cognition, assessed using objective and subjective scores, was associated with return to work 2 years after BC diagnosis., Design, Setting, and Participants: In a case series of the French Cancer Toxicities (CANTO) cohort, a study of patients with stage I to III BC investigated cognition from April 2014 to December 2018 (2 years' follow-up). Participants included women aged 58 years or younger at BC diagnosis who were employed or looking for a job., Main Outcomes and Measures: The outcome was return to work assessed 2 years after BC diagnosis. Objective cognitive functioning (tests), cognitive symptoms, anxiety, depression, and fatigue were prospectively assessed at diagnosis (baseline), 1 year after treatment completion, and 2 years after diagnosis. Multivariable logistic regression models were used to explain return to work status at year 2 according to each cognitive measure separately, adjusted for age, occupational class, stage at diagnosis, and chemotherapy., Results: The final sample included 178 women with BC (median age: 48.7 [range, 28-58] years), including 37 (20.8%) who did not return to work at year 2. Patients who returned to work had a higher (ie, professional) occupational class and were less likely to have had a mastectomy (24.1% vs 54.1%; P < .001). Return to work at year 2 was associated with lower overall cognitive impairment (1-point unit of increased odds ratio [1-pt OR], 0.32; 95% CI, 0.13-0.79; P = .01), higher working memory (1-pt OR, 2.06; 95% CI, 1.23-3.59; P = .008), higher processing speed (1-pt OR, 1.97; 95% CI, 1.20-3.36; P = .01) and higher attention performance (1-pt OR, 1.63; 95% CI, 1.04-2.64; P = .04), higher perceived cognitive abilities (1-pt OR, 1.12; 95% CI, 1.03-1.21; P = .007), and lower depression (1-pt OR, 0.83; 95% CI, 0.74-0.93; P = .001) at year 2 assessment. Return to work at year 2 was associated with several measures assessed at baseline and year 1: higher processing speed (1-pt OR, 2.38; 95% CI, 1.37-4.31; P = .003 and 1.95; 95% CI, 1.14-3.50; P = .02), higher executive performance (1-pt OR, 2.61; 95% CI, 1.28-5.75; P = .01, and 2.88; 95% CI, 1.36-6.28; P = .006), and lower physical fatigue (10-pt OR, 0.81; 95% CI, 0.69-0.95; P = .009 and 0.84; 95% CI, 0.71-0.98; P = .02)., Conclusions and Relevance: In this case series study of patients with BC, return to work 2 years after diagnosis was associated with higher cognitive speed performance before and after BC treatment. Cognitive difficulties should be assessed before return to work to propose suitable management.

Understanding breast cancer survivors' perspectives is critical to personalizing endocrine therapy (ET) in the adjuvant setting. A nationwide survey among breast cancer survivors was proposed in France, in collaboration with patient advocacy organizations, to assess their perspectives on personalizing ET and developing dedicated informative tools. This survey explored patients' preferences regarding ET intake schedule, formulation, presentation (color, taste, shape, size, design, and packaging), combination with agents targeting ET-related adverse events, and a mobile application to support them during ET. Of the 1103 individuals who started the survey, 939 (85.1%) were eligible for enrollment and completed the survey. The majority of the participants considered that a personalized ET should take into consideration the intake schedule (n = 974, 90.7%) and swallowable tablet formulation (n = 606, 64.5%), without a preference for ET presentation (n = 619; 65.9%). The majority of the participants expressed a willingness to participate in a potential clinical trial evaluating the combination of ET with agents targeting ET-related adverse events at the start of ET (n = 752, 80.1%) or in the case of major ET-related adverse events (n = 778, 82.8%). The primary considerations were to have an uncompromised ET efficacy and a guaranteed reduction of adverse events. Last, a dedicated mobile application was considered helpful by 665 participants (70.8%). Informative tools should focus on the recommendations for dealing with adverse events (n = 593, 63.2%), the impact on the patient's daily life (n = 515, 54.9%), benefits (n = 504, 53.7%), and adverse events (n = 494, 52.6%) of ET. This survey paves the way for multimodal strategies that can include a personalized ET (e.g., ET in combination with agents targeting ET-related adverse events) and dedicated mobile applications to ultimately improve adherence., (© 2024. The Author(s).)

Purpose: Previous studies have reported the benefit of dual HER2-targeting combined to neoadjuvant chemotherapy in HER2-amplified breast cancer (HER2 + BC). Moreover, besides the cardiac toxicity following their association to Trastuzumab, anthracyclines chemotherapy may not profit all patients. The NeoTOP study was designed to evaluate the complementary action of Trastuzumab and Pertuzumab, and the relevance of an anthracycline-based regimen according to TOP2A amplification status., Methods: Open-label, multicentre, phase II study. Eligible patients were aged ≥ 18 with untreated, operable, histologically confirmed HER2 + BC. After centralized review of TOP2A status, TOP2A-amplified (TOP2A+) patients received FEC100 for 3 cycles then 3 cycles of Trastuzumab (8 mg/kg then 6 mg/kg), Pertuzumab (840 mg/kg then 420 mg/kg), and Docetaxel (75mg/m 2 then 100mg/m 2 ). TOP2A-not amplified (TOP2A-) patients received 6 cycles of Docetaxel (75mg/m 2 ) and Carboplatin (target AUC 6 mg/ml/min) plus Trastuzumab and Pertuzumab. Primary endpoint was pathological Complete Response (pCR) using Chevallier's classification. Secondary endpoints included pCR (Sataloff), Progression-Free Survival (PFS), Overall Survival (OS), and toxicity., Results: Out of 74 patients, 41 and 33 were allocated to the TOP2A + and TOP2A- groups respectively. pCR rates (Chevallier) were 74.4% (95%CI: 58.9-85.4) vs. 71.9% (95%CI: 54.6-84.4) in the TOP2A + vs. TOP2A- groups. pCR rates (Sataloff), 5-year PFS and OS were 70.6% (95%CI: 53.8-83.2) vs. 61.5% (95%CI: 42.5-77.6), 82.4% (95%CI: 62.2-93.6) vs. 100% (95%CI: 74.1-100), and 90% (95%CI: 69.8-98.3) vs. 100% (95%CI: 74.1-100). Toxicity profile was consistent with previous reports., Conclusion: Our results showed high pCR rates with Trastuzumab and Pertuzumab associated to chemotherapy. They were similar in TOP2A + and TOP2A- groups and the current role of neoadjuvant anthracycline-based chemotherapy remains questioned., Trial Registration Number: NCT02339532 (registered on 14/12/14)., (© 2024. The Author(s).)

Background: Breast cancer (BC) is the second most common cancer that metastasizes to the brain. Particularly up to half of patients with human epidermal growth factor receptor 2 (HER2)-positive (HER2+) metastatic breast cancer (mBC) may develop brain metastases over the course of the disease. Nevertheless, little is known about the prevalence and the outcome of brain and leptomeningeal metastases (BLMM) in HER2-low BC. We compared the cumulative incidence of BLMM and associated outcomes among patients with HER2-low, HER2-negative (HER2-) and HER2+ mBC., Patients and Methods: This cohort study was conducted from the Epidemiological Strategy and Medical Economics (ESME) mBC database and included patients treated for mBC between 2012 and 2020 across 18 French comprehensive cancer centers and with known HER2 and hormone receptor (HR) status. The cumulative incidence of BLMM after metastatic diagnosis was estimated using a competing risk methodology with death defined as a competing event., Results: 19 585 patients were included with 6118 (31.2%), 9943 (50.8%) and 3524 (18.0%) being HER2-low, HER2- and HER2+ mBC, respectively. After a median follow-up of 48.6 months [95% confidence interval (CI) 47.7-49.3 months], BLMM were reported in 4727 patients: 1192 (25.2%) were diagnosed with BLMM at first metastatic diagnosis and 3535 (74.8%) after metastatic diagnosis. Multivariable analysis adjusted for age, histological grade, metastases-free interval and HR status showed that the risk of BLMM at metastatic diagnosis was similar in patients with HER2- compared to HER2-low mBC [odds ratio (OR) (95% CI) 1.00 (0.86-1.17)] and higher in those with HER2+ compared to HER2-low [OR (95% CI) 2.23 (1.87-2.66)]. Similar results were found after metastatic diagnosis; the risk of BLMM was similar in HER2- compared to HER2-low [subdistribution hazard ratio (sHR) (95% CI) 1.07 (0.98-1.16)] and higher in the HER2+ group [sHR (95% CI) 1.56 (1.41-1.73)]., Conclusions: The prevalence and evolution of BLMM in HER2-low mBC are similar to those in patients with HER2- tumors. In contrast to patients with HER2+ mBC, the prognosis of BLMM remains dismal in this population., Competing Interests: Disclosure WJ declares grants: AstraZeneca, Daiichi Sankyo; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events: AstraZeneca, Eisai, BMS, Lilly France, Daiichi Sankyo, MSD, Novartis, Pfizer, Roche, Seagen; support for attending meetings and/or travel: AstraZeneca, Novartis, Chugai Pharma, Pfizer, Eisai, Pierre Fabre, Glaxo Smithkline, Roche, Lilly France, Sanofi Aventis; participation on a data safety monitoring board or advisory board : AstraZeneca, Eisai, BMS, Lilly France, Daiichi Sankyo, MSD, Novartis, Pfizer, Roche, Seagen, Gilead. MA declares payment or honoraria for lectures, presentations, speaker’s bureaus, manuscript writing or educational events: Gilead, Daiichi Sankyo, Pfizer, Lilly, AstraZeneca, Novartis; support for attending meetings and/or travel: Gilead, Pfizer, Novartis; participation on a data safety monitoring board or advisory board: AstraZeneca, Novartis, Pfizer. FLD declares consulting fees: Novartis, Gilead; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events: Amgen, Daiichi, Lilly, Novartis, Seagen, AZ; support for attending meetings and/or travel: Novartis, Pfizer, Seagen; participation on a data safety monitoring board or advisory board: Daiichi, Lilly, Seagen, Pfizer, Novartis, Roche, Exact Sciences; receipt of equipment, materials, drugs, medical writing, gifts or other services : Lilly. TF declares payment or honoraria for lectures, presentations, speaker’s bureaus, manuscript writing or educational events: Roche, Jansen, Lilly. BP received fees as advisor/consultant from Pierre Fabre (self), Daiichi Sankyo (self), Merck Sharp & Dohme (institution), Seattle Genetics (institution), Eli Lilly (institution) and Novartis (institution); funding to institution for research support from Daiichi Sankyo and AstraZeneca; and travel expenses from AstraZeneca, Pfizer and Gilead. JSF declares consulting fees: Pfizer, Lilly, Novartis, AstraZeneca, Clovis Oncology, GSK, Gilead, Daiichi Sankyo, Seagen, Exact Science, MSD; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events: Lilly, Novartis, AstraZeneca, Gilead, Daiichi Sankyo, Seagen, MSD; support for attending meetings and/or travel: Pfizer, Lilly, Novartis, AstraZeneca, Clovis Oncology, GSK, Gilead, Daiichi Sankyo, Seagen, MSD. All other authors have declared no conflicts of interest., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Importance: Little is known regarding the outcomes associated with tucatinib combined with trastuzumab and capecitabine (TTC) after trastuzumab-deruxtecan exposure among patients with ERBB2 (previously HER2)-positive metastatic breast cancer (MBC)., Objective: To investigate outcomes following TTC treatment in patients with ERBB2-positive MBC who had previously received trastuzumab-deruxtecan., Design, Setting, and Participants: This cohort study included all patients with MBC who were treated in 12 French comprehensive cancer centers between August 1, 2020, and December 31, 2022., Exposure: Tucatinib combined with trastuzumab and capecitabine administered at the recommended dose., Main Outcomes and Measures: Clinical end points included progression-free survival (PFS), time to next treatment (TTNT), overall survival (OS), and overall response rate (ORR)., Results: A total of 101 patients with MBC were included (median age, 56 [range, 31-85] years). The median number of prior treatment lines for metastatic disease at TTC treatment initiation was 4 (range, 2-15), including 82 patients (81.2%) with previous trastuzumab and/or pertuzumab and 94 (93.1%) with previous ado-trastuzumab-emtansine) exposure. The median duration of trastuzumab-deruxtecan treatment was 8.9 (range, 1.4-25.8) months, and 82 patients (81.2%) had disease progression during trastuzumab-deruxtecan treatment, whereas 18 (17.8%) had stopped trastuzumab-deruxtecan for toxic effects and 1 (1.0%) for other reasons. Tucatinib combined with trastuzumab and capecitabine was provided as a third- or fourth-line treatment in 37 patients (36.6%) and was the immediate treatment after trastuzumab-deruxtecan in 86 (85.1%). With a median follow-up of 11.6 (95% CI, 10.5-13.4) months, 76 of 101 patients (75.2%) stopped TTC treatment due to disease progression. The median PFS was 4.7 (95% CI, 3.9-5.6) months; median TTNT, 5.2 (95% CI, 4.5-7.0) months; and median OS, 13.4 (95% CI, 11.1 to not reached [NR]) months. Patients who received TTC immediately after trastuzumab-deruxtecan had a median PFS of 5.0 (95% CI, 4.2-6.0) months; median TTNT of 5.5 (95% CI, 4.8-7.2) months, and median OS of 13.4 (95% CI, 11.9-NR) months. Those who received TTC due to trastuzumab-deruxtecan toxicity-related discontinuation had a median PFS of 7.3 (95% CI, 3.0-NR) months. Best ORR was 29 of 89 patients (32.6%). Sixteen patients with active brain metastasis had a median PFS of 4.7 (95% CI, 3.0-7.3) months, median TTNT of 5.6 (95% CI, 4.4 to NR), and median OS of 12.4 (95% CI, 8.3-NR) months., Conclusions and Relevance: In this study, TTC therapy was associated with clinically meaningful outcomes in patients with ERBB2-positive MBC after previous trastuzumab-deruxtecan treatment, including those with brain metastases. Prospective data on optimal drug sequencing in this rapidly changing therapeutic landscape are needed.

Improving the prognosis for patients with metastatic HR+/HER2- breast cancer remains an unmet need. Patients with tumors that have progressed on endocrine therapy and/or are not eligible for endocrine therapy had limited treatment options beyond chemotherapy. Antibody-drug conjugates are a novel and promising treatment class in this setting. Datopotamab deruxtecan (Dato-DXd) consists of a TROP2-directed humanized IgG1 monoclonal antibody attached via a serum-stable cleavable linker to a topoisomerase I inhibitor payload. TROPION-Breast01 is an ongoing phase III study that is evaluating the efficacy and safety of Dato-DXd compared with investigator's choice of standard-of-care chemotherapy in patients with inoperable or metastatic HR+/HER2- breast cancer who have received one or two prior lines of systemic chemotherapy in the inoperable or metastatic setting. Clinical Trial Registration: NCT05104866 (ClinicalTrials.gov).

Introduction: The addition of taxanes to anthracycline-based chemotherapy is considered standard of care in the treatment of breast cancer. However, there are insufficient data regarding the safety of taxanes during pregnancy. The aim of this study was to describe the incidence of obstetric and neonatal adverse events associated with the use of taxane-containing chemotherapy regimens for the treatment of breast cancer during pregnancy., Methods: This is a multicenter, international cohort study of breast cancer patients treated with taxanes during pregnancy. A descriptive analysis was undertaken to synthetize available data., Results: A total of 103 patients were included, most of whom were treated with paclitaxel and anthracyclines given in sequence during gestation (90.1%). The median gestational age at taxane initiation was 28 weeks (range = 12-37 weeks). Grade 3-4 adverse events were reported in 7 of 103 (6.8%) patients. The most common reported obstetric complications were intrauterine growth restriction (n = 8 of 94, 8.5%) and preterm premature rupture of membranes (n = 5 of 94, 5.3%). The live birth rate was 92 of 94 (97.9%), and the median gestational age at delivery was 37 weeks (range = 32-40 weeks). Admission to an intensive care unit was reported in 14 of 88 (15.9%) neonates, and 17 of 70 (24.3%) live births resulted in small for gestational age neonates. Congenital malformations were reported in 2 of 93 (2.2%)., Conclusion: Obstetric and neonatal outcomes after taxane exposure during pregnancy were generally favorable and did not seem to differ from those reported in the literature with standard anthracycline-based regimens. This study supports the use of taxanes during gestation when clinically indicated., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Sexual concerns are a major unaddressed need among survivors of breast cancer (BC) with significant negative effects on quality of life. We longitudinally analyzed sexual health over time, using patient-reported outcomes., Methods: Patients with stage I-III BC prospectively included from the CANcer TOxicity cohort (CANTO) provided data at diagnosis, then 1, 2, and 4 years afterward. Sexual concerns outcomes included poor body image (score ≤91/100), poor sexual functioning (≤16/100), poor sexual enjoyment (≤66/100), and sexual inactivity (EORTC QLQ-B23). Multivariate generalized estimating equation models assessed associations with sexual concerns after diagnosis, adjusting for age, sociodemographic, tumor, treatment, and clinical characteristics., Results: Nearly 78.1% among 7895 patients reported at least one sexual concern between diagnosis and 4 years' follow-up. Over time, the proportion of patients reporting sexual concerns either increased or remained constant with diagnosis. Less than half (46%, range 11.4-57) of the patients with sexual concerns reported the use of supportive care strategies, including gynecological or psychological consultations (range 11.4-57.4). Factors consistently associated with sexual concerns up to 4 years after diagnosis included already reporting the same concern at diagnosis [odds ratio (OR) poor body image 3.48 [95% confidence interval (CI) 3.11-3.89]; OR sexual inactivity 9.94 (95% CI 8.84-11.18), OR poor sexual function 9.75 (95% CI 8.67-10.95), OR poor sexual enjoyment 3.96 (95% CI 3.34-4.69)], endocrine therapy use [OR poor body image 1.15 (95% CI 1.01-1.31); OR sexual inactivity 1.19 (95% CI 1.02-1.39), OR poor sexual function 1.17 (95% CI 1.01-1.37), OR poor sexual enjoyment 1.23 (95% CI 1.00-1.53)], and depression [OR poor body image 2.00 (95% CI 1.72-2.34); OR sexual inactivity 1.66 (95% CI 1.40-1.97), OR poor sexual function 1.69 (95% CI 1.43-2.00), OR poor sexual enjoyment 1.94 (95% CI 1.50-2.51)]. Outcome-specific associations were also identified., Conclusions: Sexual concerns seem frequent, persistent, and insufficiently addressed. Pretreatment concerns, endocrine therapy, and emotional distress are commonly associated factors. A proactive evaluation of sexual health across the care continuum is needed, to promptly identify patients suitable for multidisciplinary counseling, referral, and supportive interventions., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Introduction: Controlled ovarian stimulation (COS) for oocyte/embryo cryopreservation is the method of choice for fertility preservation (FP) in young patients diagnosed with early-stage breast cancer (eBC). Nevertheless, some challenges still question its role, particularly in the neoadjuvant setting, where concerns arise about potential delay in the onset of anticancer treatment, and in hormone receptor-positive (HR+) disease, as cancer cells may proliferate under the estrogenic peak associated with stimulation. Therefore, this review aims to examine the available evidence on the safety of COS in eBC patients eligible for neoadjuvant treatment (NAT), particularly in HR+ disease., Methods: A comprehensive literature search was conducted to identify studies evaluating the feasibility and safety of COS in eBC and including patients referred to NAT and/or with HR+ disease. Time to NAT and survival outcomes were assessed., Results: Of the three matched cohort studies assessing the impact of COS on time to start NAT, only one reported a significant small delay in the cohort undergoing COS compared with the control group, whereas the other studies found no difference. Regarding survival outcomes, overall, no increased risk of recurrence or death was found, either in patients undergoing COS in the neoadjuvant setting regardless of HR expression or in HR+ disease regardless of the timing of COS relative to surgery. However, there are no data on the safety of COS in the specific combined scenario of HR+ disease undergoing NAT., Conclusion: Neither the indication to NAT nor the HR positivity constitutes per se an a priori contraindication to COS. Shared decision making between clinicians and patients is essential to carefully weigh the risks and benefits in each individual case. Prospective studies designed to specifically investigate this issue are warranted., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Antibody-drug conjugates (ADCs) are a rapidly expanding class of compounds in oncology. Our goal was to assess the expression of ADC targets and potential downstream determining factors of activity across pan-cancer and normal tissues., Materials and Methods: ADCs in clinical trials (n = 121) were identified through ClinicalTrials.gov, corresponding to 54 targets. Genes potentially implicated in treatment response were identified in the literature. Gene expression from The Cancer Genome Atlas (9000+ cancers of 31 cancer types), the Genotype-Tissue Expression database (n = 19,000 samples from 31 normal tissue types), and the TNMplot.com (n = 12,494 unmatched primary and metastatic samples) were used in this analysis. To compare relative expression across and within tumour types we used pooled normal tissues as reference., Results: For most ADC targets, mRNA levels correlated with protein expression. Pan-cancer target expression distributions identified appealing cancer types for each ADC development. Co-expression of multiple targets was common and suggested opportunities for ADC combinations. Expression levels of genes potentially implicated in ADC response downstream of the target might provide additional information (e.g. TOP1 was highly expressed in many tumour types, including breast and lung cancers). Metastatic compared to primary tissues overexpressed some ADCs targets. Single sample "targetgram" plots were generated to visualise the expression of potentially competing ADC targets and resistance/sensitivity markers highlighting high inter-patient heterogeneity. Off-cancer target expression only partially explains adverse events, while expression of determinants of payload activity explained more of the observed toxicities., Conclusion: Our findings draw attention to new therapeutic opportunities for ADCs that can be tested in the clinic and our web platform (https://tnmplot.com) can assist in prioritising upcoming ADC targets for clinical development., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: C.B.: Financial interests: personal consulting fees from Kardo srl (personal); travel support for attending meetings from Daiichi-Sankyo and Lilly. G.N.: Travel support for attending meetings from Lilly and Sanofi. M.M.: Travel support for attending meetings from Lilly. L.L.: Financial interests: Consulting fees from Exact Sciences, Helsinn, EISAI; honoraria for speakers’ bureaus from Gilead, Exact Sciences, Helsinn; support for attending meetings from Lilly and Gilead; advisory board for Lilly, Exact Sciences, AstraZeneca, Italfarmaco, Accord, Seagen and Daiichi Sankyo (all personal and financial). G.V.: Financial interests: Advisory board for Gilead; speakers’ bureaus: Novartis, Lilly; support for attending meetings: Pfizer, Lilly (all personal and financial). B.P.: Financial interests: Consulting fees from AstraZeneca (institutional), Seagen (institutional), Gilead (institutional), Novartis (institutional), Lilly (institutional), MSD (institutional), Pierre Fabre (personal), Daiichi-Sankyo (institutional/personal); research funding (to the institution): Astra Zeneca, Daiichi-Sankyo, Gilead, Seagen, MSD; travel support: Astra Zeneca; Pierre Fabre; MSD; Daiichi-Sankyo, Pfizer. F.A.: Financial interests: grants or speaker/Advisory compensated to hospital: AstraZeneca, Daiichi Sankyo, Pfizer, Lilly, Relay; honorarium: Lilly. M.P.: Financial interests: Travel support for attending meetings from Gilead and Novartis. C.C.: Financial interests: Personal fees for consulting, advisory role, and speakers’ bureau from Lilly, Roche, Novartis, MSD, Seagen, Gilead, Daiichi Sankyo, AstraZeneca, and Pfizer. L.P.: Financial interests: Consulting fees and honoraria for advisory board participation from Pfizer, Astra Zeneca, Merck, Novartis, Bristol-Myers Squibb, Stemline-Menarini, GlaxoSmithKline, Genentech/Roche, Personalis, Daiichi, Natera, Exact Sciences (personal), and institutional research funding from Seagen, GlaxoSmithKline, AstraZeneca, Merck, Pfizer and Bristol Myers Squibb. G.C.: Financial Interests: AstraZeneca, Invited Speaker, Personal; AstraZeneca, Advisory Board, Personal, BMS, Advisory Board, Personal; Celcuity, Advisory Board, Personal; Daiichi Sankyo, Invited Speaker, personal; Daiichi Sankyo, Advisory Board, Personal; Exact Sciences, Advisory Board, Personal; Gilead, Advisory Board, Personal, Advisory Board; Lilly, Advisory Board, Personal; Menarini, Advisory Board, Personal, Advisory Board; Merck, Advisory Board, Personal; Novartis, Invited Speaker, Personal; Pfizer, Writing Engagement, Personal; Pfizer, Advisory Board, Personal; Pfizer, Invited Speaker, Personal; Roche, Advisory Board, Personal; Roche, Invited Speaker, Personal; Veracyte, Advisory Board, Personal; Ellipsis, Other, Personal, Advisory Board; Astellas, Funding, Institutional, Financial interest, Phase I studies; AstraZeneca, Funding, Institutional, Financial interest, Phase I studies; Blueprint Medicine, Funding, Institutional, Financial interest, Phase I studies; BMS, Funding, Institutional, Financial interest, Phase I studies; Daiichi Sankyo, Funding, Institutional, Financial interest, Phase I studies; Kymab, Funding, Institutional, Financial interest, Phase I studies; Merck, Research Grant, Institutional, Financial interest, Investigator Initiated Trial; Novartis, Funding, Institutional, Financial interest, Phase I studies; Philogen, Funding, Institutional, Financial interest, Phase I studies; Relay Therapeutics, Coordinating PI, Institutional, Financial interest, Phase I clinical basket trial; Roche, Funding, Institutional, Financial interest, Phase I studies; Sanofi, Funding, Institutional, Financial interest, Phase I studies. Non-financial interests: Consiglio Superiore di Sanità, Officer, Italian National Health Council as Advisor for Ministry of Health; ESMO, Officer, ESMO Clinical Practice Guidelines Chair; ESMO, Member of Board of Directors, Chair of Clinical Practice Guidelines Committee; Europa Donna, Advisory Role, Member of the Scientific Council. Patient advocacy association; EUSOMA, Officer, Member of the Advisory Council; Fondazione Beretta, Advisory Role, Cancer Research Foundation; Lega Italiana Lotta ai Tumori, Member of Board of Directors, No compensation for this role. This a public national company for cancer prevention. G.B.: Financial Interests: AstraZeneca, Advisory Board, Personal; AstraZeneca, Other, Personal, Consultancy; Daiichi Sankyo, Advisory Board, Personal; Daiichi Sankyo, Other, Personal, Consultancy; Lilly, Advisory Board, Personal; Lilly, Invited Speaker, Personal; Novartis, Advisory Board, Personal; Pfizer, Advisory Board, Personal; Roche, Other, Personal, Consultancy; MSD, Other, Personal, Consultancy; Gilead, Other, Personal, Consultancy; Sanofi, Other, Personal, Consultancy; Roche, Invited Speaker, Personal; AstraZeneca, Invited Speaker, Personal; Daiichi Sankyo, Invited Speaker, Personal; MSD, Invited Speaker, Personal; Chugai, Invited Speaker, Personal; EISAI, Invited Speaker, Personal; Gilead, Invited Speaker, Personal; Seagen, Invited Speaker, Personal; Neopharm Israel, Invited Speaker, Personal; Roche, Other, Personal, Support for attending meetings and/or travel; Pfizer, Other, Personal, Support for attending meetings and/or travel; MSD, Other, Personal, Support for attending meetings and/or travel; Chugai, Other, Personal, Support for attending meetings and/or travel; Novartis, Other, Personal, Support for attending meetings and/or travel; Roche, Advisory Board, Personal; Amgen, Advisory Board, Personal; MSD, Advisory Board, Personal; Chugai, Advisory Board, Personal; EISAI, Advisory Board, Personal; Gilead, Advisory Board, Personal; Seagen, Advisory Board, Personal; Exact Science, Advisory Board, Personal; Roche, Advisory Board, Personal; MSD, Advisory Board, Personal; Gilead, Advisory Board, Personal; Gilead, Other, Personal, Support for attending meetings and/or travel; Daiichi Sankyo, Other, Personal, Support for attending meetings and/or travel; Roche, Steering Committee Member, Financial interest, Personal and Institutional; Novartis, Steering Committee Member, Financial interest, Personal and Institutional; Lilly, Steering Committee Member, Financial interest, Personal and Institutional; AstraZeneca, Steering Committee Member, Financial interest, Personal and Institutional; Gilead, Local PI, Financial interest, Institutional; Pfizer, Local PI, Financial interest, Institutional; Daiichi Sankyo, Local PI, Financial interest, Institutional; Lilly, Local PI, Financial interest, Institutional; MSD, Local PI, Financial interest, Institutional; Novartis, Local PI, Financial interest, Institutional; Non-Financial Interests: Fondazione Michelangelo, Leadership Role, Head of Traslational Research. A.B., B.Ga, H.R.A., M.C., M.B., A.L., L.V., M.D., M.M.N., and B.G. declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Approximately 20% of breast cancers (BCs) overexpress human epidermal growth factor receptor 2 (HER2), a transmembrane glycoprotein with tyrosine kinase activity, encoded by ERBB2 gene. Historically, HER2 overexpression has been linked with increased disease recurrence and a worse prognosis. However, the increasing availability of different anti-HER2 compounds and combinations is progressively improving HER2-positive BC outcome, thus requiring expertise to prioritize both overall survival (OS) prolongation and quality of life, without neglecting the accessibility to further treatment lines with a low attrition rate. In this context, tucatinib, an oral tyrosine kinase inhibitor, has recently been granted approval by regulatory agencies based on evidence from the HER2CLIMB, a clinical trial which randomized patients with metastatic BC to receive trastuzumab and capecitabine with either tucatinib or placebo. A distinctive feature of this study was the inclusion of patients with new or active brain metastases (BMs) at study entry, a population traditionally excluded from clinical trials. Thus, HER2CLIMB provides the first solid evidence of an OS benefit in patients with BC and BMs, addressing a long standing unmet medical need, especially given the high incidence of central nervous system metastatic spread in patients with HER2-positive disease. This review provides an overview of the molecular and clinical landscape of tucatinib for the treatment of advanced BC. It focuses on the technological journey that drove the development of this therapeutic innovation, from preclinical data to clinical practice., Competing Interests: Declaration of Competing Interest CCr reports personal fees for consulting, advisory role and speakers’ bureau from Lilly, Roche, Novartis, MSD, Seagen, Gilead and Pfizer. All the competing interests were outside the submitted work. CCo has no potential conflicts of interest to disclose. MDL reports honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Eli Lilly, Novartis, Seagen, Takeda, Roche, Daiichi Sankyo, Tomalab, Gilead, Genetic, Menarini, Sophos; support for attending meetings and/or travel from Gilead, Novartis, Roche, AstraZeneca; fees for participation on a Data Safety Monitoring Board or Advisory Board from Pfizer, AstraZeneca, Sanofi, Seagen, Novartis, Ipsen, Roche, Pierre-Fabre, Daiichi-Sankyo, GSK. All the competing interests were outside the submitted work. GB is a consultant and/or advisory board member for Amgen, AstraZeneca, Chugai, Daiichi Sankyo, EISAI, Eli Lilly, Genomic Health, Merck Sharp & Dohme, Neopharm, Novartis, Pfizer, Roche and Sanofi. All the competing interests were outside the submitted work. BP has no potential conflicts of interest to disclose. SC reports current presidency of the Italian Association of Medical Oncology (AIOM). All the competing interests were outside the submitted work. LC has no potential conflicts of interest to disclose. GA has no potential conflicts of interest to disclose. PC reports personal fees from Novartis, Eli Lilly, AstraZeneca, Tesaro, Daiichi Sankyo, and Gilead, revealing Genomics, BMS, and Roche. All the competing interests were outside the submitted work. FDM has no potential conflicts of interest to disclose. AG has no potential conflicts of interest to disclose. VG reports personal fees from Eli Lilly, Exact Sciences, Novartis, Pfizer, Gilead, MSD, Amgen, Sanofi, Merck Serono, and Eisai. All the competing interests were outside the submitted work. LV has no potential conflicts of interest to disclose. LL has no potential conflicts of interest to disclose. PM declares grants to his Institution from Roche, BMS, Pfizer, Incyte, Novartis, Takeda, MSD, Pierre Fabre; personal payments from Roche, BMS, MSD, Novartis, Pfizer, Pierre Fabre; personal support for congress attendance from BMS, Roche; is President of the Italian Foundation of Personalized Medicine, of AIOM Servizi s.r.l., of the Steering and Verification Board of the ’Regina Elena’ National Cancer Institute. All the competing interests were outside the submitted work. FP reports honoraria for advisory boards, activities as a speaker, travel grants, research grants from Amgen, AstraZeneca, Daiichi Sankyo, Celgene, Eisai, Eli Lilly, Exact Sciences, Gilead, Ipsen, Menarini, MSD, Novartis, Pierre Fabre, Pfizer, Roche, Seagen, Takeda, Viatris; research funding from AstraZeneca, Eisai, Roche. All the competing interests were outside the submitted work. GV has no potential conflicts of interest to disclose. LDM reports institutional grants or contracts from Eli Lilly, Novartis, Roche, Daiichi Sankyo, Seagen, AstraZeneca, Gilead; personal consulting fees from Eli Lilly; personal honoraria for lectures, presentations, speakers bureau, manuscript writing or educational events from Roche, Novartis, Pfizer, Eli Lilly, AstraZeneca, MSD, Seagen, Gilead, Pierre Fabre, Eisai, Exact Sciences, Ipsen, GSK, Agendia, Stemline; support for attending meetings and/or travel from Roche, Pfizer, Eisai, Daiichi Sankyo, AstraZeneca; personal fees for participation on a Data Safety Monitoring Board or Advisory Board from Novartis, Roche, Eli Lilly, Pfizer, Daiichi Sakyo, Exact Sciences, Gilead, Pierre Fabre, Eisai, Astrazeneca, Agendia, GSK, Seagen. All the competing interests were outside the submitted work. SDP reports personal fees for consulting or advisory role from Roche, Novartis, Pfizer, Lilly, Celgene, AstraZeneca/MedImmune, Seattle Genetics, Daiichi Sankyo/AstraZeneca, MSD. All the competing interests were outside the submitted work. GC reports personal fees for consulting, advisory role and speakers’ bureau from Roche/Genentech, Novartis, Pfizer, Lilly, Foundation Medicine, Samsung and Daiichi Sankyo; honoraria from Ellipses Pharma and fees for travel and accommodations from Roche/Genentech and Pfizer. All the competing interests were outside the submitted work., (Copyright © 2023 Elsevier Ltd. All rights reserved.)