Human Epidermal Growth Factor 2 Expression Research Articles

Tumor immune microenvironmental characteristics in Human Epidermal Growth Factor-2 (HER2) positive esophageal adenocarcinoma: A comparative analysis and biomarker study

BackgroundHER2 targeting in esophageal adenocarcinoma (EAC) has shown potential, but often fails to show durable response. Given the contributions of the tumor immune microenvironment (TIME) to therapeutic responses, we aimed to chart the TIME characteristics of HER2 positive tumors. Methods84 biopsies were taken from the TRAP cohort (neoadjuvant chemoradiotherapy (nCRT) according to CROSS with trastuzumab and pertuzumab; n = 40; HER2+n = 40) and a control cohort with nCRT only (n = 44; HER2- n = 40, HER2+n = 4) before treatment. Biopsies were analysed using targeted gene expression analysis (Nanostring immune-oncology panel, 750 genes). Differential gene expression was assessed between HER2 positive (n = 44) vs. negative biopsies (n = 40), and non-responders (n = 17) vs. responders (n = 23) to anti-HER2 treatment. Statistical significance was determined as p-value <0.05, adjusted for multiple testing correction. Results83 biopsies were eligible for analyses following quality control (TRAP cohort n = 40; control cohort n = 43); there were no significant differences in clinical characteristics between the TRAP vs. control the cohort or HER2 positive vs. HER2 negative biopsies. HER2 expression was found to associate with epithelial markers (EPCAM p < 0.001; E-cadherin p < 0.001). Moreover, HER2 expression was associated with a lower expression of immune cell infiltration, such as NK-cells (p < 0.001) and CD8 T-cells (p < 0.001), but also lower expression of immune exhaustion markers (PDCD1LG2, CTLA4; p < 0.001). In non-responders to anti-HER2 treatment, baseline biopsies showed increased expression of immune exhaustion markers, as well as hypoxia and VEGF signalling. DiscussionHER2 expression was associated with epithelial tumor characteristics. The HER2 positive TIME showed reduced immune cell infiltration but also lower expression of inhibitory signals associated with immune exhaustion, questioning the mechanism behind potential clinical benefit of co-administration of anti-HER2 agents and checkpoint inhibitors. As limited response was associated with increased VEGF signalling, studies could investigate potential synergism of targeting VEGF and HER2.

Resistance to Anti-HER2 Therapies in Gastrointestinal Malignancies.

Human epidermal growth factor 2 (HER2) is a tyrosine kinase receptor that interacts with multiple signaling pathways related to cellular growth and proliferation. Overexpression or amplification of HER2 is linked to various malignancies, and there have been decades of research dedicated to targeting HER2. Despite the landmark ToGA trial, progress in HER2-positive gastrointestinal malignancies has been hampered by drug resistance. This review examines current HER2 expression patterns and therapies for gastroesophageal, colorectal, biliary tract, and small bowel cancers, while dissecting potential resistance mechanisms that limit treatment effectiveness.

Quantitative comparison of immunohistochemical HER2-low detection in an interlaboratory study.

Recently, human epidermal growth factor 2 (HER2)-low (i.e. HER2 score 1+ or 2+ without amplification) breast cancer patients became eligible for trastuzumab-deruxtecan treatment. To improve assay standardisation and detection of HER2-low in a quantitative manner, we conducted an external quality assessment-like study in the Netherlands. Dynamic range cell lines and immunohistochemistry (IHC) calibrators were used to quantify HER2 expression and to assess interlaboratory variability. Three blank slides with a dynamic range cell line and an IHC calibrator were stained with routine HER2 assays by 35 laboratories. Four different antibody clones were used: 19 (54.3%) 4B5, six (17.1%) A0485, five (14.3%) DG44 (HercepTest) and five (14.3%) SP3. Laboratories used two different detection kits for 4B5 assays: 14 (73.7%) ultraView and five (26.3%) OptiView. Variability of HER2 expression in cell lines, measured with artificial intelligence software, was median (min-max) = negative core 0.5% (0.0-57.0), 1+ core 4.3% (1.6-71.3), 2+ core 42.8% (30.4-92.6) and 3+ core 96.2% (91.8-98.8). The calibrators DG44 and 4B5 OptiView had the highest analytical sensitivity, closely followed by 4B5 ultraView. SP3 was the least sensitive. Calibrators of A0485 assays were not analysable due to background staining. As assays were validated for detecting HER2-amplified tumours, not all assays and antibodies proved suitable for HER2-low detection. Some tests showed distinct expression in the negative cell line. Dynamic range cell line controls and quantitative analysis using calibrators demonstrated more interlaboratory variability than commonly appreciated. Revalidation of HER2 tests by laboratories is needed to ensure clinical applicable HER2-low assays.

Human epidermal growth factor 2 (HER2) amplification in uterine serous carcinoma: an analysis of prognosis and immune microenvironment.

Uterine serous carcinoma (USC) is a biologically aggressive subtype of endometrial cancer. Anti-human epidermal growth factor receptor 2 (HER2) therapy has demonstrated its promising effects on HER2-positive USC. However, data on prognostic relevance and immune microenvironment are limited in HER2-positive USC. This study aimed to determine the clinicopathologic features, prognosis, and the immune microenvironment trait in HER2 status in USC. We applied immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and multi-color immunofluorescence to investigate HER2 expression and amplification, PD-L1 expression, and tumor infiltration lymphocytes (TIL) in 77 USC (61 pure and 16 mixed-type USC). HER2 IHC 1 + , 2 + , and 3 + were found in 26, 18, and 10 USC, respectively. HER2 staining frequently had an incomplete membrane (basolateral or "U"-shaped) pattern. Twenty-three cases (23/54, 42.6%) showed an intra-tumor heterogeneous staining. HER2 amplification was present in 16/77 (20.8%) USC. HER2 amplification was significantly associated with deep myometrial invasion (> 1/2), and increased intra-epithelial and stromal density of CD20 + or CD8 + TIL (all P < 0.05), but not with USC subtypes (pure versus mixed-type), PD-L1 expression, CD4 + TIL, CD68 + histiocytes, or the CD4 + /CD8 + ratio (p > 0.05). HER2 amplification was associated with poor overall and progression-free survival in USC, but lost the prognostic significance on multivariate analysis. We concluded that HER2 amplified USC had adverse clinical outcomes, but showed the potential active immune microenvironment. Our findings raised the possibility of the combined anti-HER2 and immunotherapy for HER2-positive USC in the future.

The frequency of HER2-low breast cancer among BRCA1, BRCA2, and PALB2 mutation carriers.

10509 Background: Human epidermal growth factor 2 (HER2) expression in breast cancer (BC) has historically been characterized as negative (0 or 1+ by immunohistochemistry (IHC); 2+ by IHC and not amplified by in-situ hybridization, ISH) or positive (2+ by IHC and amplified by ISH or 3+ by IHC). Recently developed therapies highlight the importance of identifying tumors that are HER2-low (IHC 1+, or 2+ with negative ISH). A minority of BC associated with germline BRCA1, BRCA2( BRCA1/2) or PALB2pathogenic variants (PV) are HER2-positive, but the proportion of BRCA1/2- and PALB2-associated HER2-negative BC that are HER2-low and may benefit from novel HER2-low therapies is unknown.This study aims to retrospectively identify the frequency of HER2-low BC in BRCA1/2 and PALB2 mutation carriers whose cancers were identified as HER2-negative. Methods: We conducted a retrospective chart review of 170 patients diagnosed with HER2-negative BC in the context of a BRCA1/2or PALB2PV at the University of Pennsylvania from 2003 to 2023. Genomic and cancer-specific characteristics including variant classification and receptor status were collected and are descriptively reported. Results: 170 individuals with BRCA1/2 or PALB2 PV developed 190 HER2-negative BC. Forty-seven percent of primary tumors that had been identified as HER2-negative were HER2-low (39% of BRCA1-, 56% of BRCA2-,60% of PALB2-associated BC; see Table). 17 individuals had 17 metastatic site biopsy reports available for review. Of these, 10 (59%) were HER2-low (1 BRCA1-, 8 BRCA2-, and 1 PALB2-associated). 6 of 17 (35%) individuals had discordant HER2 status in primary and metastatic samples; in all cases, the primary tumor was HER2 IHC 0 and the metastatic site was HER2-low. Conclusions: Despite the lower frequency of conventionally HER2-positive BC among individuals with BRCA1/ 2and PALB2PVs, the proportion of these BC that have low HER2 expression is substantial and similar to that of sporadic breast cancer. Discordance in HER2 status between primary and metastatic samples is observed. Individuals with BRCA1/2and PALB2HER2-negative BC may benefit from therapies for HER2-low BC; reevaluation of HER2 status on metastatic samples may identify additional candidates for such therapies. [Table: see text]

Utility of human epidermal growth factor 2 heterogeneity as a prognostic factor in triple-negative breast cancer.

In some cases of human epidermal growth factor 2 (HER2)-negative breast cancer, including triple-negative breast cancer, HER2 expression is sporadically and strongly upregulated, a condition known as HER2 heterogeneity. We investigated the clinicopathological features of patients with HER2 heterogeneity in triple-negative breast cancers treated with neoadjuvant chemotherapy. Thirty-nine patients with triple-negative breast cancer who had undergone preoperative chemotherapy participated in this study. To assess for HER2 heterogeneity, we used dual in situ hybridization slides. We evaluated the association between HER2 heterogeneity and clinicopathological factors such as rates of pathologic complete response (pCR) and of recurrence-free survival. Of the 39 patients, 15 (38.5%) had cancers with HER2 heterogeneity. The pCR rates were 13.3% among patients with HER2 heterogeneity and 20.8% among those with HER2 nonheterogeneity, but the difference was not significant. The recurrence-free survival rate was significantly lower in patients with HER2 heterogeneity than in those without (P = 0.025). HER2 heterogeneity is a significant predictor of poor prognosis in patients with triple-negative breast cancer treated with neoadjuvant chemotherapy.

Association between Homologous Recombination Repair Defect Status and Long-Term Prognosis of Early HER2-Low Breast Cancer: A Retrospective Cohort Study.

As a newly identified subtype of HER2-negative tumors associated with a less favorable prognosis, it remains crucial to evaluate potential prognostic and predictive factors, particularly non-invasive biomarkers, for individuals with human epidermal growth factor 2 (HER2) low early-stage breast cancer (EBC). Multiple investigations have highlighted that HER2-negative patients with EBC exhibiting high homologous recombination deficiency (HRD) scores display lower rates of pathological complete response (PCR) to neoadjuvant chemotherapy (NAC). Nevertheless, no study to date has explored the correlation between HRD and the long-term prognosis in HER2-low patients with EBC. This retrospective observational study focuses on primary EBC sourced from The Cancer Genome Atlas dataset (TCGA). It reveals the gene mutation landscape in EBC with low HER2 expression and elucidates the tumor immune landscape across different HRD states. Utilizing bioinformatics analysis and Cox proportional models, along with the Kaplan-Meier method, the study assesses the correlation between HRD status and disease-specific survival (DSS), disease-free interval (DFI), and progression-free interval (PFI). Subgroup analyses were conducted to identify potential variations in the association between HRD and prognosis. In the patients with HER2-low breast cancer, patients with homologous recombination related genes (HRRGs) defects had an HRD score about twice that of those without related genes mutations, and were at higher risk of acquiring ARID1A, ATM, and BRCA2 mutations. We also found that most immune cell abundances were significantly higher in EBC tumors with high HRD than in EBC tumors with low HRD or HRD-medium, particularly plasma B-cell abundance, CD8 T-cell abundance, and M1 macrophages. In addition, these tumors with HRD-high also appear to have significantly higher tumor immune scores and lower interstitial scores. Then, we analyzed the relationship between different HRD status and prognosis. There was statistical significance (P = .036 and P = .046, respectively) in DSS and PFI between the HRD-low and HRD-high groups, and patients with HRD-high EBC showed relatively poor survival outcomes. A medium HRD score (hazard ratio, HR = 2.15, 95% CI: 1.04-4.41, P = .038) was a significant risk factor for PFI. Hormone receptor positivity is an important factor in obtaining medium-high HRD score and poor prognosis. Higher HRD scores were associated with poorer PFI outcomes, particularly in people with HR+/HER2-low. Varied HRD states exhibited distinctions in HRRGs and the tumor immune landscape. These insights have the potential to assist clinicians in promptly identifying high-risk groups and tailoring personalized treatments for patients with HER2-low EBC, aiming to enhance long-term outcomes.

The values of HER-2 expression in the non-muscle-invasive bladder cancer: a retrospective clinical study

PurposeThe purpose of this research is to evaluate the association between HER-2 expression and clinicopathological features in patients with non-muscle-invasive bladder cancer (NMIBC).MethodsBetween 2019 and 2022, 204 patients treated with Transurethral resection of the bladder tumor (TURBT) were included in this study. Data of pathologic T (pT) stage, grades of the tumor, age, sex, tumor size and number of the tumors were collected and compared according to the expression level of the human epidermal growth factor 2 (HER-2). ROC curve analysis was performed to assess the discriminative ability of HER-2 expression for tumors grades and pT stage. Multivariable logistic regression analysis were used to evaluate the association between HER-2 expression and tumor grades and pT stage.ResultsPatients were divided into low grade (110, 53.9%) and high grade groups (94, 46.1%) according to the tumor grade. Pathologic stage consisted of pTa in 166 (81.4%) and pT1 in 38 (18.6%). HER-2 expression was semi quantitatively scored to 0 in 44 (21.6%), 1 in 58 (28.4%), 2 in 91 (44.6%), and 3 in 11 (5.4%) cases. HER-2 expression was significantly associated with tumor stages and histological grades, but not with sex, tumor size or number of tumors. The AUC for combination of HER-2 expression with tumor stages and histological grades was 0.652 (p &amp;lt; 0.003) and 0.727 (p &amp;lt; 0.001), respectively.ConclusionThis study demonstrated that HER-2 expression is associated with tumor stages and histological grades in NMIBC. It has diagnostic value for cystoscopic biopsy.

HER2-low heterogeneity between primary and paired recurrent/metastatic breast cancer: Implications in treatment and prognosis.

With the largest sample size to date, the authors' objective was to investigate the incidence of primary-to-metastatic human epidermal growth factor 2 (HER2) conversion and the predictors for such conversion. Moreover, no previous studies have evaluated the prognosis of patients who have negative HER2 expression (HER2-0) versus low HER2 expression (HER2-low) when HER2 status was assessed based on all recurrent/metastatic lesions. The authors included 1299 patients who had available HER2 status of primary breast tumors and paired recurrent/metastatic lesions at Fudan University Shanghai Cancer Center and West China Hospital. In total, 370 patients (28.5%) experienced primary-to-metastatic HER2 conversion. Intrapatient intermetastasis spatial heterogeneity and temporal heterogeneity of HER2 were detected. When assessing HER2 based on recurrent/metastatic tumors, patients who had HER2-0 tumors had significantly shorter overall survival than those who had HER2-low tumors in the overall population and in the estrogen receptor (ER)-negative subgroup. However, when assessing HER2 based on primary tumors, there was no difference in overall survival between patients who had HER2-0 versus HER2-low tumors. Moreover, patients who had tumors that converted from HER2-0 to HER2-low had longer overall survival than those who had consistent HER2-0 status in the ER-negative subgroup. By combining four predictors (ER status, Ki67 index, biopsy site, and disease-free interval), the authors established the first prediction tool to estimate the probability of HER2-0 tumors converting to HER2-low/positive tumors. Intrapatient primary-to-metastatic and intermetastatic HER2 heterogeneity were observed in this large-scale cohort study. When evaluating HER2 based on recurrent/metastatic tumors, an overall survival difference was observed between patients who had HER2-0 versus HER2-low, recurrent/metastatic breast tumors. The developed prediction tool might help clinicians screen out patients with primary HER2-0 tumors that have a high probability of HER2 status conversion and recommend them for re-biopsy, thus helping to screen out candidate patients for trastuzumab deruxtecan treatment.

Human epidermal growth factor receptor-2 gene expression positivity determined by silver in situ hybridization/immunohistochemistry methods and associated factors in a cohort of Sri Lankan patients with gastric adenocarcinoma: a prospective study.

Positive human epidermal growth factor 2 (HER2) expression and its predictive clinicopathological features remain unclear in Sri Lankan gastric cancer (GC) patients. Here, we aimed to determine GC HER2 status predictors by analyzing associations between clinicopathological features and HER2 expression using immunohistochemistry (IHC) and silver in situ hybridization (SISH). During this 4-year prospective study, clinicopathological data were collected from participants in the National Hospital of Sri Lanka. HER2 IHC and SISH were performed using commercial reagents. Using chi-square tests, associations of HER2-IHC/SISH with clinicopathological features were analyzed. Overall, 145 GC patients were included, 69 had gastrectomies and 76 had biopsies. Positive HER2 expression by IHC was associated with age <60 years, high T stage (assessed pathologically in resections and radiologically in biopsies), high nuclear grade, tumor necrosis, mitosis >5/high-power field, with additional perineural invasion and lymphovascular invasion in resections. These features, excluding lymphovascular invasion but including male sex, were associated with HER2 expression by SISH. Age <60 years, high nuclear grade, tumor necrosis, and perineural invasion are associated factors of HER2 status. These could be used to triage GC patients for HER2 status testing in limited resource settings where IHC/SISH analysis is costly.

Clinicopathologic Features and Prognosis of Female Early Breast Cancer With HER2 Low Expression: A Propensity Score Matched Analysis.

Metastatic breast cancer (MBC) patients with low expression of human epidermal growth factor 2 (HER2) have been proven to benefit from HER2 targeted therapy. We aimed to determine how HER2-low status affected survival and metastatic risk as well as how it affected pathological complete response (pCR) in neoadjuvant chemotherapy (NAC) patients. According to the results of immunohistochemistry (IHC) and in situ hybridization (ISH) testing, 321 female patients were sorted into HER2-low (IHC 1+/2+ with ISH negative) and HER2-zero (IHC 0) groups using propensity score matching (PSM). Overall survival (OS), disease-free survival (DFS), and distant disease-free survival (DDFS) were compared for both groups, while pCR was only analyzed for NAC patients. In total, 97 patients in each group after PSM were included. We discovered that pCR was not associated with HER2 expression status in 45 patients who underwent NAC. Five-year OS in the HER2-low group was significantly higher (98.99%) than in the HER2-zero group (95.87%, P = .044); however, this difference was not reflected in the 5-year DFS (90.61 vs 90.52%, P = .868) and 5-year DDFS (93.67 vs 91.53%, P = .757). Meanwhile, multivariate analysis revealed that HER2-low expression could indicate better OS (P = .047, hazard ratios [HRs] = 16.121, 95% confidence interval [CI] = 1.035-251.046), but it had no prognostic value for DFS or DDFS. When compared with HER2-zero expression, HER2-low expression was not connected to pCR and could not modify metastasis risk in female patients with early-stage breast cancer (BC), but it may prolong patient survival.

Prognostic effect of HER2 evolution from primary breast cancer to breast cancer metastases

PurposeTherapeutic options for breast cancer (BC) treatment are constantly evolving. The Human Epidermal Growth Factor 2 (HER2)-low BC entity is a new subgroup, representing about 55% of all BC patients. New antibody–drug conjugates demonstrated promising results for this BC subgroup. Currently, there is limited information about the conversion of HER2 subtypes between primary tumor and recurrent disease.MethodsThis retrospective study included women with BC at the University Medical Centre Wuerzburg from 1998 to 2021. Data were retrieved from patients' records. HER2 evolution from primary diagnosis to the first relapse and the development of secondary metastases was investigated.ResultsIn the HR-positive subgroup without HER2 overexpression, HER2-low expression in primary BC was 56.7 vs. 14.6% in the triple-negative subgroup (p < 0.000). In the cohort of the first relapse, HER2-low represented 64.1% of HR-positive vs. 48.2% of the triple-negative cohort (p = 0.03). In patients with secondary metastases, HER2-low was 75.6% vs. 50% in the triple negative subgroup (p = 0.10). The subgroup of HER2-positive breast cancer patients numerically increased in the course of disease; the HER2-negative overall cohort decreased. A loss of HER2 expression from primary BC to the first relapse correlated with a better OS (p = 0.018). No clinicopathological or therapeutic features could be identified as potential risk factors for HER2 conversion.ConclusionHER2 expression is rising during the progression of BC disease. In view of upcoming therapeutical options, the re-analysis of newly developed metastasis will become increasingly important.

Breast cancer management in 2021: A primer for the obstetrics and gynecology.

Breast cancer is the most commonly diagnosed cancer and is the leading cause of cancer death in women worldwide. Several factors increase the risk of breast cancer development, including patient characteristics, lifestyle habits, and predisposing genetic mutations. Once a diagnosis of breast cancer has been established, treatment decisions are guided by breast cancer stage and phenotype. Immunohistochemistry is used to quantify estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2) expressions. In this chapter, we will focus on the management of localized and metastatic breast cancer, guided by the breast cancer hormone receptor status (ER and PR expression) and HER2 expression identified at diagnosis.

Clinicopathologic and molecular features associated with response to anti-HER2 therapy in endometrial cancer.

5584 Background: Endometrial cancer (EC) is the most common gynecologic malignancy in the United States. Human epidermal growth factor 2 (HER2) overexpression or gene amplification occurs in 10-60% of EC. The addition of trastuzumab to carboplatin-paclitaxel chemotherapy improves survival in women with HER2-positive serous EC. However, criteria for assessment of HER2 status in EC are not standardized, and furthermore, intratumor heterogeneity may impact therapeutic efficacy. We aimed to identify factors associated with treatment response and survival outcomes in a retrospective cohort of ECs treated with anti-HER2 therapy. Methods: Patients with advanced/recurrent EC treated with trastuzumab or trastuzumab emtansine alone or in combination with chemotherapy from 2013-2021 at our institution were identified. Clinical and treatment information were retrieved from medical records. Central pathology review, HER2 immunohistochemistry (IHC) and fluorescence in-situ hybridization (FISH) were performed. HER2 IHC was scored using modified ASCO/CAP 2007 guidelines for breast cancer. HER2 expression heterogeneity was defined as a 2-degree difference in staining intensity in ≥5% of tumor cells or discordant IHC score on different specimens. HER2 amplification (tumor/normal fold change) was also estimated from targeted next-generation sequencing (NGS). Best response was assessed by RECIST v1.1 as complete response (CR), partial response (PR), stable disease (SD), or progressive disease (PD), with clinical benefit defined as CR/PR/SD. Results: Among 39 patients included, median age was 69. Histologic subtypes included serous (n = 18, 46%), carcinosarcoma (n = 7, 18%), high-grade EC with ambiguous features (n = 13, 33%) and low-grade endometrioid carcinoma (n = 1, 3%). HER2 IHC results were 0 or 1+ (n = 2, 5%), 2+ (n = 17, 46%), 3+ (n = 18, 49%), with HER2 heterogeneity in 15 cases. By FISH, the HER2/CEP17 ratio was ≥2.0 in 34 (92%) and &lt; 2.0 in 3 (8%); HER2 copy number (CN) was ≥6.0 in 25 (68%) and &lt; 6.0 in 12 (32%). HER2 copy number ≥6.0 was significantly correlated with HER2 amplification by NGS ( p&lt; 0.001). 18 (49%) patients had a co-existing somatic PIK3CA mutation. Amongst parameters assessed, only higher level of HER2 amplification by NGS was significantly associated with clinical benefit ( p= 0.036). None of these features were associated with progression-free survival. Notably, 2 patients with IHC 0/1+ had PD and 1 patient with IHC 3+, but non-amplified by FISH, achieved PR. Conclusions: In our cohort of EC patients treated with anti-HER2 therapy, higher level of HER2 amplification was associated with clinical benefit. Further studies with larger sample sizes are needed to determine whether any additional characteristics are associated with treatment response and survival.

Heterogeneity between Core Needle Biopsy and Synchronous Axillary Lymph Node Metastases in Early Breast Cancer Patients-A Comparison of HER2, Estrogen and Progesterone Receptor Expression Profiles during Primary Treatment Regime.

Simple SummaryAll initial therapeutic decisions in early breast cancer are commonly based on the intrinsic subtype consisting of estrogen (ER), progesterone (PR), the human epidermal growth factor 2 (HER2) receptors and the proliferation marker Ki67. However, breast cancer is a very heterogeneous disease, and receptor expression is reported to change during progression. Little is known about receptor changes at the primary site. In a German single center study, we retrospectively analyzed a mostly therapy naive cohort of 215 primary breast cancer patients with axillary synchronous lymph node metastases (LNM). We compared core needle biopsy tissue of the primary tumor (t-CNB) to axillary LNM and detected receptor discordance for all three receptors at the primary site.In breast cancer therapeutic decisions are based on the expression of estrogen (ER), progesterone (PR), the human epidermal growth factor 2 (HER2) receptors and the proliferation marker Ki67. However, only little is known concerning heterogeneity between the primary tumor and axillary lymph node metastases (LNM) in the primary site. We retrospectively analyzed receptor profiles of 215 early breast cancer patients with axillary synchronous LNM. Of our cohort, 69% were therapy naive and did not receive neoadjuvant treatment. Using immunohistochemistry, receptor status and Ki67 were compared between core needle biopsy of the tumor (t-CNB) and axillary LNM obtained during surgery. The discordance rates between t-CNB and axillary LNM were 12% for HER2, 6% for ER and 20% for PR. Receptor discordance appears to already occur at the primary site. Receptor losses might play a role concerning overtreatment concomitant with adverse drug effects, while receptor gains might be an option for additional targeted or endocrine therapy. Hence, not only receptor profiles of the tumor tissue but also of the synchronous axillary LNM should be considered in the choice of treatment.

HER2-Low Breast Cancer: Prognosis and Future Treatment Prospective

The human epidermal growth factor 2 (HER2) is a tyrosine kinase belonging to the Human Epidermal Receptor family [1]. HER2 is amplified leading to HER2 overexpression in 15% of breast cancers (BC) [2]. HER2 overexpression leads to poor prognosis, but offers the unique possibility to use a targeted therapy with monoclonal antibodies. This therapeutic option has radically changed the history of HER2 BC [3]. HER2 overexpression represents at present the most powerful predictive factor for likeliness of response to anti-HER2 agents [5]. The HER2 status is routinely assessed either using immunohistochemistry (HER2 protein expression level) or in situ hybridization (HER2 gene status) [2,5,6]. For the purpose of HER2 assessment, international guidelines have been developed by experts in the field, and have changed over the years according to new data. HER2 heterogeneity is linked to the complexity of equivocal results, HER2 mutations and the upcoming category of HER2-low BC [7]. Intratumor genetic heterogeneity interests various types of human cancers, including BC and HER2 overexpression and amplification, and it is demonstrated to be significantly more common in cases with HER2 equivocal status [8]. Equivocal cases frequently feature low levels of HER2 amplification. Several studies showed that HER2 heterogeneity is related to poor outcome, shorter disease-free survival and overall survival. Patients with HER2 heterogeneity are less responsive to target therapies as confirmed by a lower achievement of pathologic complete response following neoadjuvant treatment [9]. In spite of the scarcity of data still available on HER2-low BC, different intrinsic subtypes seem to influence different clinical behavior and response to treatment, as this has already been proved for other BC subtypes. HER2-low/HR- BC showed a higher frequency of HER2-enriched instrinsic subtype than HER2-/HR- BC. This might mean that, despite in clinical practice HER2-low/HR- BC is considered as HER2-/HR, these subtypes of BCs might reflect a different clinical behavior and a different response to targeted therapy [10]. Recent studies underlined that HER2-enriched instrinsic subtype are the most beneficial in reduction of risk of progression and death after CDK6/6-inhibitors treatment, compared to the other subtypes [11]. Traditionally HER2-positive BCs were separated from HER2-negative BCs, based on solid clinical data stating that only tumors driven by HER2 oncogene addition benefit from targeted therapies [12]. However in recent years new therapies have been developed, in particular the antibody drug conjugates which deliver chemotherapy inside the BC. Some of these agents - such as trastuzumab duocarmazine and trastuzumab deruxtecan showed encouraging response rates also in the so called HER2-low BC. For example, the phase 1 study of DS-8201 showed an overall response rate of 37% in pretreated HER2-low metastatic cancer patients, with a median duration of response of 10.4 months [13]. These data suggests a paradigm shift in the definition of HER2 status, which may be based on 3 groups: 1.HER2-positive, 2.HER2- negative, 3.HER2-low BCs, that may potentially benefit from a targeted therapy, even in absence of the addition of the tumor cells to the HER2 oncogene [7]. At present there are no formal definitions of HER2-low BC, but it seems reasonable to define as HER2-low all BCs displaying a score of 1+ or 2+ HER2 expression and no HER2 amplification. This assumption would categorize up to 55% of BCs as HER2-low. For this subtype there are no targeted therapies approved [7]. The majority of HER2 somatic mutations found in BCs have not been associated with HER2 gene amplification. However preclinical data suggest that functionally active HER2 mutations may lead to HER2 targeted therapies sensitivity [14]. Other preclinical models suggest that pertuzumab inhibits tumor proliferation even in absence of HER2 overexpression [15].So, HER2 mutation-positive but HER2-negative BC may benefit from targeted drugs, but further studies are needed. For example, trastuzumab, deruxtecan, a novel enzyme-cleavable linker, showed significant objective response and disease control in a group of patients including 25% HER2-low BCs, and therefore is worthy of further studies in this subgroup of patients [16]. The new agents being tested for HER2-low BC patients are antibody drug conjugates deploying anti-HER2 epitopes in their antibody component, but with different cytotoxic warheads and a bi-specific antibody targeting both HER2 and HER3 [17]. In conclusion, the concept of HER2-positive versus HER2-negative disease is changing, including the definition of “HER2-low” BC, against which new therapies such as antibody drug conjugates may be extremely effective.

Abstract P1-03-01: Heterogeneity between core needle biopsy and primary tumor tissue in early breast cancer patients: Comparison of intrinsic subtypes after different treatment regimes

Abstract Background: All initial therapeutic decisions in early breast cancer are commonly based on the expression profiles of estrogen (ER), progesterone (PR) and the human epidermal growth factor 2 (HER2) receptors. However, breast cancer is a very heterogeneous disease, and receptor changes were manifold reported during progression. Only little data is known about receptor changes after upfront therapy. Here, we compared receptor expression profiles between core needle biopsy (CNB) tissue and primary tumor tissue after different treatment regimes. Methods: In a German single center study, we retrospectively analyzed 248 breast cancer patients during primary treatment regime between 2014 and 2020. Patients had either neoadjuvant chemotherapy, neoadjuvant endocrine therapy or no upfront therapy. Tumor material was obtained by core needle biopsy (CNB) at primary diagnosis and during primary oncological surgery of the axilla and breast. Analysis of histological subtype, grading, Ki67 index and expression profiling of ER, PR, HER2, was performed using formalin-fixed, paraffin-embedded (FFPE) specimens. Immunohistochemical examination was performed according to the ASCO/CAP guidelines using the Ventana-platform. Tumors were grouped into different intrinsic subtypes according to the international St. Gallen classification in either Luminal A, Luminal B, HER2-enriched or triple negative. 35 patients were excluded because the intrinsic subtype was not specified in the CNB and final postoperative specimen, therefore 213 patients were included in the primary analysis. Results: In the primary analysis (n=213), median age was 53 years (IQR 43 - 64). Based on the initial CNB receptor profile 105 (49%) patients had a Luminal A carcinoma, 46 (22%) patients had a Luminal B HER2 negative carcinoma, 22 (10%) patients had a Luminal B HER2 positive carcinoma, 6 (3%) patients had a HER2 enriched carcinoma and 33 (16%) patients had a triple negative carcinoma. In the primary analysis 84 (39%) patients had neoadjuvant chemotherapy, 48 (23%) patients had neoadjuvant endocrine therapy and 81 (38%) patients had no upfront therapy. Overall, 77 (36%) patients had an intrinsic subtype change between CNB and definitive surgical treatment, 139 (64 %) patients had no subtype change. There were 44 (52%) changes after neoadjuvant chemotherapy, 17 (35%) changes after neoadjuvant endocrine therapy and 16 (20%) subtype changes after no upfront therapy (p&amp;lt;0.0001 for the effect of neoadjuvant chemotherapy). ER receptor status changed in 5 (6%) patients after neoadjuvant chemotherapy, 6 (13%) changes were observed after neoadjuvant endocrine therapy and 2 (2%) ER changes occurred after no upfront therapy. Concerning the PR receptor there were 23 (27%) receptor changes after neoadjuvant chemotherapy, 17 (35%) changes after neoadjuvant endocrine therapy and 9 (11%) changes after no upfront therapy (p&amp;lt;0.0001 for the effect of neoadjuvant endocrine therapy). Regarding the HER2 receptor, there were 18 (21%) receptor status changes after neoadjuvant chemotherapy, 2 (4%) changes after neoadjuvant endocrine therapy and 2 (2%) subtype changes after no upfront therapy (p=0.0001 for the effect of neoadjuvant chemotherapy).Neoadjuvant chemotherapy led significantly more often to a decrease of HER2 expression, compared to neoadjuvant endocrine therapy or no upfront therapy. Conclusions: Our results imply the high frequency of intrinsic subtype changes after neoadjuvant therapy. Subtype changes should be taken into account for an optimal and individual treatment. Further research needs to be conducted to investigate whether an individual treatment decision based on the receptor profile after primary treatment might improve clinical outcome of breast cancer patients. Citation Format: Laura Weydandt, Anne Kreklau, Ivonne Nel, Lars-Christian Horn, Bahriye Aktas. Heterogeneity between core needle biopsy and primary tumor tissue in early breast cancer patients: Comparison of intrinsic subtypes after different treatment regimes [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-03-01.

Multimodal Imaging Technology Effectively Monitors HER2 Expression in Tumors Using Trastuzumab-Coupled Organic Nanoparticles in Patient-Derived Xenograft Mice Models.

Trastuzumab is a monoclonal antibody targeting human epidermal growth factor 2 (HER2), which has been successfully used in the treatment of patients with breast cancer and gastric cancer; however, problems concerning its cardiotoxicity, drug resistance, and unpredictable efficacy still remain. Herein, we constructed novel organic dopamine–melanin nanoparticles (dMNs) as a carrier and then surface-loaded them with trastuzumab to construct a multifunctional nanoprobe named Her-PEG-dMNPs. We used micro-PET/CT and PET/MRI multimodality imaging to evaluate the retention effect of the nanoprobe in HER2 expression in gastric cancer patient-derived xenograft (PDX) mice models after labeling of the radionuclides 64Cu or 124I and MRI contrast agent Mn2+. The nanoprobes can specifically target the HER2-expressing SKOV-3 cells in vitro (3.61 ± 0.74 vs. 1.24 ± 0.43 for 2 h, P = 0.002). In vivo, micro-PET/CT and PET/MRI showed that the 124I-labeled nanoprobe had greater contrast and retention effect in PDX models than unloaded dMNPs as carrier (1.63 ± 0.07 vs. 0.90 ± 0.04 at 24 h, P = 0.002), a similarity found in 64Cu-labeled Her-PEG-dMNPs. Because 124I has a longer half-life and matches the pharmacokinetics of the nanoparticles, we focused on the further evaluation of 124I-Her-PEG-dMNPs. Furthermore, immunohistochemistry staining confirmed the overexpression of HER2 in the animal model. This study developed and validated novel HER2-specific multimodality imaging nanoprobes for quantifying HER2 expression in mice. Through the strong retention effect of the tumor site, it can be used for the promotion of monoclonal antibody treatment effect and process monitoring.

Comparison of Different Molecular Subtypes with 14% Ki-67 Cut-off Threshold in Breast Cancer Patients of Pakistan- An Indication of Poor Prognosis

Ki-67 is a proliferation marker that is used not only to categorize patients in luminal A and B subtypes of breast cancers, but also to determine the aggressiveness of the disease in triple negative and human epidermal growth factor 2 (HER2) over expressed molecular subtypes. The present study was designed to evaluate the role of Ki-67 with cut off value of 14% in molecular subgroups and its association with patient prognosis. Immunostaining was performed on histopathologically confirmed sections (n = 278) to assess expression of Ki-67, estrogen receptor (ER), progesterone receptor (PR) and HER2. Immunoreactivity of molecules was recorded as percentage scoring. Adopting a cut off value of 14%, Ki-67 was high in 88%of the cases included in the study. High Ki-67 was significantly associated with pathological parameters including histological grade, advanced stage and nodal/distant metastasis. Immunoexpression of ER, PR and HER2 also showed strong correlation with high expression of Ki-67. Based on the St. Gallen classification, the cases were categorized into luminal A (10%) and luminal B (51%), triple negative (20%) and HER2 enriched (18%). Ki-67 index was also significantly high in 98% of HER2 enriched and 95% of TNBC patients. Interestingly, Ki-67 score with cut off value of 14% proved to be significant in deciphering prognosis in luminal patients. Moreover, high expression of Ki-67 also proved to be a marker of poor prognosis, especially in triple negative patients. We suggest that utilization of IHC4 status i.e. ER, PR, HER2 and Ki-67 along with pathological findings and molecular subtyping can considerably affect clinical as well as therapeutic decisions.

Nanobody-Based Theranostic Agents for HER2-Positive Breast Cancer: Radiolabeling Strategies.

The overexpression of human epidermal growth factor 2 (HER2) in breast cancer (BC) has been associated with a more aggressive tumor subtype, poorer prognosis and shorter overall survival. In this context, the development of HER2-targeted radiotracers is crucial to provide a non-invasive assessment of HER2 expression to select patients for HER2-targeted therapies, monitor response and identify those who become resistant. Antibodies represent ideal candidates for this purpose, as they provide high contrast images for diagnosis and low toxicity in the therapeutic setting. Of those, nanobodies (Nb) are of particular interest considering their favorable kinetics, crossing of relevant biological membranes and intratumoral distribution. The purpose of this review is to highlight the unique characteristics and advantages of Nb-based radiotracers in BC imaging and therapy. Additionally, radiolabeling methods for Nb including direct labeling, indirect labeling via prosthetic group and indirect labeling via complexation will be discussed, reporting advantages and drawbacks. Furthermore, the preclinical to clinical translation of radiolabeled Nbs as promising theranostic agents will be reported.