Clinical best practices in interdisciplinary management of human epidermal growth factor receptor 2 antibody-drug conjugates-induced interstitial lung disease/pneumonitis: An expert consensus in China.

Antibody-drug conjugates (ADCs) have demonstrated effectiveness in treating various cancers, particularly exhibiting specificity in targeting human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Recent advancements in phase 3 clinical trials have broadened current understanding of ADCs, especially trastuzumab deruxtecan, in treating other HER2-expressing malignancies. This expansion of knowledge has led to the US Food and Drug Administration's approval of trastuzumab deruxtecan for HER2-positive and HER2-low breast cancer, HER2-positive gastric cancer, and HER2-mutant nonsmall cell lung cancer. Concurrent with the increasing use of ADCs in oncology, there is growing concern among health care professionals regarding the rise in the incidence of interstitial lung disease or pneumonitis (ILD/p), which is associated with anti-HER2 ADC therapy. Studies on anti-HER2 ADCs have reported varying ILD/p mortality rates. Consequently, it is crucial to establish guidelines for the diagnosis and management of ILD/p in patients receiving anti-HER2 ADC therapy. To this end, a panel of Chinese experts was convened to formulate a strategic approach for the identification and management of ILD/p in patients treated with anti-HER2 ADC therapy. This report presents the expert panel's opinions and recommendations, which are intended to guide the management of ILD/p induced by anti-HER2 ADC therapy in clinical practice.

A Case Report on Trastuzumab Emtansine (T-DM1) in a Patient With Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Metastatic Breast Cancer and Brain Metastases: Long-Term Treatment and Survival.

Breast cancer remains the most common cancer in women worldwide. Among women with breast cancer, brain metastases are very prevalent among HER2-positive and affect those in the advanced stages of the disease. Various factors, including molecular subtypes, performance status, extracranial disease status, leptomeningeal metastasis, and the number of lesions, significantly influence the prognosis of patients with brain metastases from breast cancer (BCBrM). Understanding and addressing the specific risks associated with different breast cancer subtypes is crucial for developing tailored and effective medical treatments. This report presents a case of a breast cancer patient with recurrent disease and brain metastases who achieved long-term survival following a treatment regimen that included radiotherapy and a T-DM1 biosimilar.

Bag-1-mediated HSF1 phosphorylation regulates expression of heat shock proteins in breast cancer cells.

According to the World Health Organization in 2022, 2.3 million women were diagnosed with breast cancer. Investigating the interaction networks between Bcl-2-associated athanogene (Bag)-1 and other chaperone proteins may further the current understanding of the regulation of protein homeostasis in breast cancer cells and contribute to the development of treatment options. The present study aimed to determine the interactions between Bag-1 and heat shock proteins (HSPs); namely, HSP90, HSP70 and HSP27, to elucidate their role in promoting heat shock factor-1 (HSF1)-dependent survival of breast cancer cells. HER2-negative (MCF-7) and HER2-positive (BT-474) cell lines were used to examine the impact of Bag-1 expression on HSF1 and HSPs. We demonstrated that Bag-1 overexpression promoted HER2 expression in breast cancer cells, thereby resulting in the concurrent constitutive activation of the HSF1-HSP axis. The activation of HSP results in the stabilization of several tumor-promoting HSP clients such as AKT, mTOR and HSF1 itself, which substantially accelerates tumor development. Our results suggest that Bag-1 can modulate the chaperone activity of HSPs, such as HSP27, by directly or indirectly regulating the phosphorylation of HSF1. This modulation of chaperone activity can influence the activation of genes involved in cellular homeostasis, thereby protecting cells against stress.

Mechanisms of action and resistance to anti-HER2 antibody-drug conjugates in breast cancer.

Human epidermal growth factor 2 (HER2)-positive breast cancer (BC) represents nearly 20% of all breast tumors. Historically, these patients had a high rate of relapse and dismal prognosis. The advent of HER2-targeting monoclonal antibodies such as trastuzumab followed by pertuzumab had improved the prognosis of HER2-positive metastatic BC. More recently, antibody-drug conjugates (ADCs) are now reshaping the treatment paradigm of solid tumors, especially breast cancer. Tratsuzumab emtansine (T-DM1) was one of the first ADC developed in oncology and was approved for the management of HER2-positive metastatic BC. In a head-to-head comparison, trastuzumab deruxtecan (T-DXd) defeated T-DM1 as a second-line treatment. The efficacy of ADCs is counterbalanced by the appearance of acquired resistance to these agents. In this paper, we summarize the mechanisms of action and resistance of T-DM1 and T-DXd, as well as their clinical efficacy. Additionally, we also discuss potential strategies for addressing resistance to ADC.

Artificial intelligence for assisted HER2 immunohistochemistry evaluation of breast cancer: A systematic review and meta-analysis.

Accurate assessment of HER2 expression in tumor tissue is crucial for determining HER2-targeted treatment options. Nevertheless, pathologists' assessments of HER2 status are less objective than automated, computer-based evaluations. Artificial Intelligence (AI) promises enhanced accuracy and reproducibility in HER2 interpretation. This study aimed to systematically evaluate current AI algorithms for HER2 immunohistochemical diagnosis, offering insights to guide the development of more adaptable algorithms in response to evolving HER2 assessment practices. A comprehensive data search of the PubMed, Embase, Cochrane, and Web of Science databases was conducted using a combination of subject terms and free text. A total of 4994 computational pathology articles published from inception to September 2023 identifying HER2 expression in breast cancer were retrieved. After applying predefined inclusion and exclusion criteria, seven studies were selected. These seven studies comprised 6867 HER2 identification tasks, with two studies employing the HER2-CONNECT algorithm, two using the CNN algorithm, one with the multi-class logistic regression algorithm, and two using the HER2 4B5 algorithm. AI's sensitivity and specificity for distinguishing HER2 0/1+ were 0.98 [0.92-0.99] and 0.92 [0.80-0.97] respectively. For distinguishing HER2 2+, the sensitivity and specificity were 0.78 [0.50-0.92] and 0.98 [0.93-0.99], respectively. For HER2 3+ distinction, AI exhibited a sensitivity of 0.99 [0.98-1.00] and specificity of 0.99 [0.97-1.00]. Furthermore, due to the lack of HER2-targeted therapies for HER2-negative patients in the past, pathologists may have neglected to distinguish between HER2 0 and 1+, leaving room for improvement in the performance of artificial intelligence (AI) in this differentiation. AI excels in automating the assessment of HER2 immunohistochemistry, showing promising results despite slight variations in performance across different HER2 status. While incorporating AI algorithms into the pathology workflow for HER2 assessment poses challenges in standardization, application patterns, and ethical considerations, ongoing advancements suggest its potential as a widely effective tool for pathologists in clinical practice in the near future.

Development and biological evaluation of 68Ga-labeled peptides for potential application in HER2-positive colorectal cancer.

Colorectal cancer (CRC) is among the most lethal and prevalent malignancies in the world. Human epidermal growth factor receptor 2 (HER2) is a promising target for the diagnosis and treatment of CRC. In this study, we aimed to design, synthesize and label peptide-based positron emission tomography (PET) tracers targeting HER2-positive CRC, namely [68Ga]Ga-ES-01 and [68Ga]Ga-ES-02. The results show that [68Ga]Ga-ES-01 and [68Ga]Ga-ES-02 possessed hydrophilicity, rapid pharmacokinetic properties and excellent stabilities. [68Ga]Ga-ES-02 demonstrated higher binding affinity (Kd = 24.29 ± 4.95 nM) toward the HER2 in CRC. In HER2-positive HT-29 CRC xenograft mouse model, PET study showed specific tumor uptake after injection of [68Ga]Ga-ES-02 (SUV15min max = 0.87 ± 0.03; SUV30min max = 0.64 ± 0.02). In biodistribution study, the T/M ratios of 68Ga-ES-02 at 30 min after injection reached a maximum of 4.07 ± 0.34. In summary, we successfully synthesized and evaluated two novel peptide-based PET tracers. Our data demonstrate that [68Ga]Ga-ES-01/02 is capable of HER2-positive colorectal cancer, with [68Ga]Ga-ES-02 showing superior imaging effect, enhanced targeting, and increased specificity.

Unraveling the future: Innovative design strategies and emerging challenges in HER2-targeted tyrosine kinase inhibitors for cancer therapy.

Human epidermal growth factor receptor 2 (HER2) is a transmembrane receptor-like protein with tyrosine kinase activity that plays a vital role in processes such as cell proliferation, differentiation, and angiogenesis. The degree of malignancy of different cancers, notably breast cancer, is strongly associated with HER2 amplification, overexpression, and mutation. Currently, widely used clinical HER2 tyrosine kinase inhibitors (TKIs), such as lapatinib and neratinib, have several drawbacks, including susceptibility to drug resistance caused by HER2 mutations and adverse effects from insufficient HER2 selectivity. To address these issues, it is essential to create innovative HER2 TKIs with enhanced safety, effectiveness against mutations, and high selectivity. Typically, SPH5030 has advanced to phase I clinical trials for its strong suppression of four HER2 mutations. This review discusses the latest research progress in HER2 TKIs, with a focus on the structural optimization process and structure-activity relationship analysis. In particular, this study highlights promising design strategies to address these challenges, providing insightful information and inspiration for future development in this field.

Targeted HER2-positive cancer therapy using ADAPT6 fused to horseradish peroxidase.

Targeted cancer therapy is a promising alternative to the currently established cancer treatments, aiming to selectively kill cancer cells while sparing healthy tissues. Hereby, molecular targeting agents, such as monoclonal antibodies, are used to bind to cancer cell surface markers specifically. Although these agents have shown great clinical success, limitations still remain such as low tumor penetration and off-target effects. To overcome this limitation, novel fusion proteins comprised of the two proteins ADAPT6 and Horseradish Peroxidase (HRP) were engineered. Cancer cell targeting is hereby enabled by the small scaffold protein ADAPT6, engineered to specifically bind to human epidermal growth factor receptor 2 (HER2), a cell surface marker overexpressed in various cancer types, while the enzyme HRP oxidizes the nontoxic prodrug indole-3-acetic acid (IAA) which leads to the formation of free radicals and thereby to cytotoxic effects on cancer cells. The high affinity to HER2, as well as the enzymatic activity of HRP, were still present for the ADAPT6-HRP fusion proteins. Further, in vitro cytotoxicity assay using HER2-positive SKOV-3 cells revealed a clear advantage of the fusion proteins over free HRP by association of the fusion proteins directly to the cancer cells and therefore sustained cell killing. This novel strategy of combining ADAPT6 and HRP represents a promising approach and a viable alternative to antibody conjugation for targeted cancer therapy.

Efficacy and prognosis of HER2-Low and HER2-Zero in triple-negative breast cancer after neoadjuvant chemotherapy.

Mounting evidence showed that HER2-Low breast cancer patients could benefit from the novel anti-HER2 antibody-drug conjugates (ADCs) treatment, which pointed the way towards better therapy for HER2-Low patients. The purpose of this study was to describe the clinicopathological features, along with chemotherapeutic effects and survival outcomes of HER2-Low and HER2-Zero in TNBC who received neoadjuvant chemotherapy (NACT). We retrospectively evaluated 638 triple-negative breast cancer patients who were treated with neoadjuvant chemotherapy between August 2014 and August 2022. Pathologic complete response (pCR) and survival outcomes were analyzed in HER2-Low cohort, HER2-Zero cohort and the overall patients, respectively. In the entire cohort, 342 (53.6%) patients were HER2-Low and 296 (46.4%) patients were HER2-Zero. No significant difference was found between HER2-Low and HER2-Zero patients based on all the clinical-pathological characteristics. 143 cases (22.4%) achieved pCR after NACT in the overall TNBC patients. The pCR rate of the HER2-Low patients and the HER2-Zero patients was 21.3% and 23.6%, respectively, exhibiting no statistical difference (p = 0.487). The survival of pCR group after NACT significantly improved compared to non-pCR group either in HER2-Low patients or in HER2-Zero patients. Although we found that patients with HER2-Low had longer DFS than patients with HER2-Zero, there was no considerable difference (p = 0.068). However, HER2-Low patients had a dramatically longer OS than HER2-Zero patients (p = 0.012). The data from present study confirmed the clinical importance of HER2-Low expression in TNBC. Further effort is needed to determine whether HER2-Low could be a more favorable prognostic marker for individual treatment.

Characteristics of Invasive Cribriform Carcinoma.

Invasive cribriform carcinoma (ICC) is a type of malignant tumor with slow growth and good prognosis. The study was a single center retrospective study. The percentage of ICC among patients diagnosed with breast cancer was 0.3% (8/2454 patients). All patients tested positive for estrogen or progesterone receptors and 12.5% (1/8) patients tested positive for human epidermal growth factor receptor type2 (HER2). The present study suggests that the clinicopathological features of ICC are low-grade hormone receptor-positive luminal type with a good prognosis. However, some patients were HER2-positive and require careful follow-up.

Histogenetic insights and genetic landscape of fibromatosis-like undifferentiated gastric carcinoma: a focused study.

BACKGROUND: The aim of this study was to elucidate the histogenesis and genetic underpinnings of fibromatosis-like undifferentiated gastric carcinoma (FLUGC), a rare pathological entity. METHOD: Through a detailed analysis of seven cases, including histopathological evaluation, CTNNB1 gene mutation screening, human epidermal growth factor receptor 2 (HER2) protein level quantification, and HER2 gene amplification assessment to identify the pathological and molecular characteristics of FLUGC. RESULTS: Of the seven patients in this study, five were male and two were female (age: 39-73 years). Four patients presented with lesions in the gastric antrum and three had lesions in the lateral curvature of the stomach. Histopathologically, over 90% of the tumor consisted of aggressive fibromatosis-like tissue, including proliferating spindle fibroblasts and myofibroblasts and varying amounts of collagenous fibrous tissues. Undifferentiated cancer cells, accounting for less than 10%, were dispersed among the aggressive fibromatosis-like tissues. These cells were characterized by their small size and were relatively sparse without glandular ducts or nested mass-like structures. Immunophenotyping results showed positive expression of CKpan, CDX2, villin, and p53 in undifferentiated cancer cells; positive expression of vimentin in aggressive fibromatosis-like tissue; positive cytoplasmic expression of ß-catenin; and focal cytoplasmic positive expression of smooth muscle actin (SMA). Genetic analysis did not reveal any mutations in the CTNNB1 gene test, nor was there amplification in the HER2 gene fluorescence in situ hybridization (FISH) test. Additionally, the Epstein-Barr encoding region (EBER) of in situ hybridization was negative; and the mismatch repair (MMR) protein was positive. Programmed cell death-1 (PD-1) was < 1-5%; programmed cell death ligand 1 (PD-L1): TPS = 1-4%, CPS = 3-8. CONCLUSION: The study highlights the significance of CTNNB1, HER2, EBER, and MMR as pivotal genetic markers in FLUGC, underscoring their relevance for diagnosis and clinical management. The rarity and distinct pathological features of FLUGC emphasize the importance of accurate diagnosis to prevent underdiagnosis or misdiagnosis and to raise awareness within the medical community.

IKZF3 amplification predicts worse prognosis especially in intestinal-type gastric cancer.

PURPOSE: IKAROS family zinc finger 3 (IKZF3) is an oncogene involved in different malignancies, particularly in the development and malignant progression of lymphocytes. However, IKZF3 amplification and clinical significance in gastric cancers (GCs) remain unexplored. METHODS: We examined IKZF3 amplification status in 404 GCs with HER2 amplification status using tissue microarray (TMA) and fluorescence in situ hybridization (FISH) assays. RESULTS: IKZF3 amplification was detected in 6.9% (28/404) of all GC patients, with higher rates in intestinal-type gastric cancer (IGC) (11.22%, 22/196) compared to other types (2.88%, 6/208). HER2 amplification was identified in 16.09% (65/404) of all GC patients, with higher rates in IGC (20.92%, 41/196) compared to other types (11.54%, 24/208). Co-amplification of IKZF3 and HER2 was detected in 8.16% (16/196) of IGC patients and in 2.40% (5/208) of other types. IKZF3 amplification showed significant correlation with IGC (P = 0.001) and HER2 amplification (P = 0.0001). IKZF3 amplification exhibited significantly worse disease-free survival (DFS) (P = 0.014) and overall survival (OS) (P = 0.018) in GC patients, particularly in IGC (DFS: P < 0.001; OS: P < 0.001), rather than other types. Cox regression analysis demonstrate IKZF3 amplification as an independent poor prognostic factor in all GCs (P = 0.006, P = 0.004 respectively) and in IGC patients, regardless of stages I-II or III-IV (P = 0.007, P = 0.004 respectively). On the other hand, HER2 amplification was significantly associated with worse DFS (P = 0.008) and OS (P = 0.01) in IGC patients, but not in all GCs and in multivariate analysis. Within the subset of patients with HER2 amplification, those also exhibiting IKZF3 amplification displayed potential poorer prognosis (P = 0.08, P = 0.11 respectively). CONCLUSION: IKZF3 amplification was detected in minority of GC patients, especially in IGC, and was an independent indicator of poor prognosis. Our study, for the first time, found the prognostic value of IKZF3 was superior to HER2 for GC patients.

Cost-utility and budget impact analysis of neoadjuvant dual HER2 targeted therapy for HER2-positive breast cancer in Sri Lanka.

This study aimed to assess the cost-utility and budget impact of dual to single HER2 targeted neoadjuvant therapy for HER2-positive breast cancer in Sri Lanka. A five-health state Markov model with lifetime horizon was used to assess the cost-utility of neoadjuvant trastuzumab (T) plus pertuzumab (P) or lapatinib (L) compared to single therapy of T with chemotherapy (C), in public healthcare system and societal perspectives. Input parameters were estimated using local data, network meta-analysis, published reports and literature. Costs were adjusted to year 2021 (1USD = LKR194.78). Five-year budget impact for public healthcare system was assessed. Incremental cost-effectiveness ratios in societal perspective for neoadjuvantLTC plus adjuvantT (strategy 3), neoadjuvantPTC plus adjuvantT (strategy 2), neoadjuvantLTC plus adjuvantLT (strategy 5), and neoadjuvantPTC plus adjuvantPT (strategy 4) compared to neoadjuvantTC plus adjuvantT (strategy 1) were USD2716, USD5600, USD6878, and USD12127 per QALY gained, respectively. One GDP per-capita (USD3815) was considered as the cost-effectiveness threshold for the analysis. Even though only the ICER for strategy 3 was cost-effective, uncertainty of efficacy parameter was revealed. For strategy 2 neoadjuvant PTC plus adjuvant T, a 25% reduction of neoadjuvant regimen cost was required to be cost effective for use in early HER2 positive breast cancer.

Germline rare variants in HER2-positive breast cancer predisposition: a systematic review and meta-analysis.

Introduction: Approximately 10% of breast cancer (BC) cases result from hereditary causes. Genetic testing has been widely implemented in BC care to determine hereditary cancer syndromes and personalized medicine. Thus, identification of individuals carrying germline pathogenic variants could be useful to provide appropriate prophylactic or screening measures for each BC subtype, however, there are few formal recommendations for genetic testing in this sense so far. In this study, we assessed rare germline variants in a specific group of genes in order to determine the association with human epidermal growth factor 2 enriched (HER2+) BC phenotype through a systematic review and meta-analysis comparing subtypes overexpressing HER2 with other clinically recognized subtypes of BC. This review was registered with PROSPERO (ID: CRD42023447571). Methods: We conducted an online literature search in PubMed (MEDLINE), Scopus, and EMBASE databases. We included original studies that investigated germline variants in HER2+ BC patients and selected the studies that reported only rare and/or pathogenic germline variants. We assessed the risk of bias and quality of the studies using the Joanna Briggs Institute Critical Appraisal checklists and the Modified Newcastle-Ottawa Scale for Genetic Studies, respectively. Considering hormone receptor and HER2 expression status, we compared gene-based risks initially in HR-HER2-, HR+HER2-, HR+HER2+, and HR-HER2+ groups, conducting separate meta-analyses using the random effects model for each comparison, and within them for each gene. Results: Of the total 36 studies describing germline variants, 11 studies provided information on the prevalence of variants in the different clinically relevant BC subtypes and allowed comparisons. Germline variants within eight genes showed significant differences when meta-analyzed between the BC groups: BRCA1, BRCA2, TP53, ATM, CHEK2, PALB2, RAD51C, and BARD1. Notably, TP53, ATM, and CHEK2 germline variants were identified as predisposing factors for HER2+ subtypes, whereas BRCA1, BRCA2, PALB2, RAD51C, and BARD1 germline variants were associated with a predisposition to low HER2 expression. Main concerns about bias and quality assessment were the lack of confounding factors control; and comparability or outcome assessment, respectively. Discussion: Our findings underscore the connection between germline variants and differential expression of the HER2 protein and BC subtypes. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO, identifier CRD42023447571.

Tailoring neo/adjuvant systemic therapy in breast cancer: "The advent of a personalized approach"-The Breast-Gynecological and Immuno-Oncology International Cancer Conference (BGICC) consensus and recommendations.

BACKGROUND: The management of early breast cancer (BC) has witnessed an uprise in the use of neoadjuvant therapy and a remarkable reshaping of the systemic therapy postneoadjuvant treatment in the last few years, with the evolution of many controversial clinical situations that require consensus. METHODS: During the 14th Breast-Gynecological and Immuno-Oncology International Cancer Conference held in Egypt in 2022, a panel of 44 BC experts from 13 countries voted on statements concerning debatable challenges in the neo/adjuvant treatment setting. The recommendations were subsequently updated based on the most recent data emerging. A modified Delphi approach was used to develop this consensus. A consensus was achieved when ≥75% of voters selected an answer. RESULTS AND CONCLUSIONS: The consensus recommendations addressed different escalation and de-escalation strategies in the setting of neoadjuvant therapy for early BC. The recommendations recapitulate the available clinical evidence and expert opinion to individualize patient management and optimize therapy outcomes. Consensus was reached in 63% of the statements (52/83), and the rationale behind each statement was clarified.

A randomized phase 2 study of HLX22 plus trastuzumab biosimilar HLX02 and XELOX as first-line therapy for HER2-positive advanced gastric cancer.

BACKGROUND: Gastric cancer is the fifth most common cancer and the fourth most common cause of cancer death worldwide, yet the prognosis of advanced disease remains poor. METHODS: This was a randomized, double-blinded, phase 2 trial (ClinicalTrials.gov: NCT04908813). Patients with locally advanced/metastatic HER2-positive gastric/gastroesophageal junction cancer and no prior systemic antitumor therapy were randomized 1:1:1 to 25 mg/kg HLX22 (a novel anti-HER2 antibody) + HLX02 (trastuzumab biosimilar) + oxaliplatin and capecitabine (XELOX) (group A), 15 mg/kg HLX22 + HLX02 + XELOX (group B), or placebo + HLX02 + XELOX (group C) in 3-week cycles. Primary endpoints were progression-free survival (PFS) and objective response rate (ORR) assessed by independent radiological review committee (IRRC). FINDINGS: Between November 29, 2021, and June 6, 2022, 82 patients were screened; 53 were randomized to group A (n = 18), B (n = 17), and C (n = 18). With 14.3 months of median follow-up, IRRC-assessed median PFS was prolonged with the addition of HLX22 (A vs. C, 15.1 vs. 8.2 months, hazard ratio [HR] 0.5 [95% confidence interval (CI) 0.17-1.27]; B vs. C, not reached vs. 8.2 months, HR 0.1 [95% CI 0.04-0.52]). Confirmed ORR was comparable among groups (A vs. B vs. C, 77.8% vs. 82.4% vs. 88.9%). Treatment-related adverse events (TRAEs) were observed in 18 (100%), 16 (94.1%), and 17 (94.4%) patients, respectively. One (5.6%) patient in group C reported a grade 5 TRAE. CONCLUSIONS: Adding HLX22 to HLX02 and XELOX prolonged PFS and enhanced antitumor response in the first-line treatment of HER2-positive gastric cancer, with manageable safety. FUNDING: Shanghai Henlius Biotech, Inc.

Successful treatment of enormous locally advanced breast cancer through neoadjuvant chemotherapy and surgical intervention: a case report.

Background: Breast cancer has become a critical international healthcare issue. Specifically, among the different subtypes, breast cancer marked by human epidermal growth factor receptor 2 (HER2)-overexpression usually correlates with low survival and a poor prognosis and poses challenges in treatment, thus leading to high mortality. Case Description: A 54-year-old female patient was diagnosed with a large T4cN2aM0 stage IIIB breast tumor with HER2 overexpression. The tumor size was large, and there was a lack of opportunity for surgery. However, after neoadjuvant chemotherapy (NACT), the size of the tumor continuously shrank, and the patient successfully underwent a modified radical mastectomy. Even though a certain amount of mass remained and she did not complete six courses of NACT, our patient's postoperative pathological result still revealed that a pathological complete response (pCR) was achieved. The appropriate time window for choosing surgical intervention should be determined based on the patient's general condition instead of complying with the treatment guidelines. Also, imaging findings may be misleading in patients who have undergone NACT. Moreover, the regimen should be chosen flexibly. Conclusions: Patients with locally advanced breast cancer can still achieve a radical surgical resection following appropriate comprehensive treatment. Hopefully, this case can provide new ideas for surgeons when they face similar conditions.

Pathological Changes Following Neoadjuvant Endocrine Therapy (NAET): A Multicentre Study of 391 Breast Cancers.

Oestrogen receptor (ER)-positive breast cancer (BC) is generally well responsive to endocrine therapy. Neoadjuvant endocrine therapy (NAET) is increasingly being used for downstaging ER-positive tumours. This study aims to analyse the effect of NAET on a well-characterised cohort of ER-positive BC with particular emphasis on receptor expression. This is a retrospective United Kingdom (UK) multicentre study of 391 patients who received NAET between October 2012 and October 2020. Detailed analyses of the paired pre- and post-NAET morphological changes and hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) expression were performed. The median duration of NAET was 86 days, with median survival and overall survival rates of 380 days and 93.4%, respectively. A total of 90.3% of cases achieved a pathological partial response, with a significantly higher rate of response in the HER2-low cancers. Following NAET, BC displayed some pathological changes involving the tumour stroma including central scarring and an increase in tumour infiltrating lymphocytes (TILs) and tumour cell morphology. Significant changes associated with the duration of NAET were observed in tumour grade (30.6% of cases), with downgrading identified in 19.3% of tumours (p < 0.001). The conversion of ER status from positive to low or negative was insignificant. The conversion of progesterone receptor (PR) and HER2 status to negative status was observed in 31.3% and 38.1% of cases, respectively (p < 0.001). HER2-low breast cancer decreased from 63% to 37% following NAET in the paired samples. Significant morphological and biomarker changes involving PR and HER2 expression occurred following NAET. The findings support biomarker testing on pre-treatment core biopsies and post-treatment residual carcinoma.