HER2 Expression Research Articles

Abstract A046: Development of a scoring system to classify HER2 protein expression in circulating tumor cells through immunofluorescence following isolation using Parsortix® instruments

Abstract Background. HER2 testing through immunohistochemistry (IHC) is routinely performed on tissue biopsy samples from metastatic breast cancer (MBC) patients, resulting in a HER2 score that is used in patient stratification and treatment decisions. However, tissue biopsy is invasive, with little opportunity for re-examination while liquid biopsy is minimally invasive and allows monitoring of disease progression through recurrent sample collection. This study aimed to establish an assay (Research Use Only) allowing scoring of HER2 protein expression in circulating tumor cells (CTCs), by immunofluorescence (IF) staining, using cancer cell lines of known HER2 expression. Method. Cultured cancer cell lines with HER2 expression comparable to tissue samples (i.e. HER2 0, 1+, 2+ and 3+ by IHC score) were used in this study (SKBR3 [3+], HCC1954 [3+], SKOV-3 [2+/3+], ZR-75-1 [2+], MCF-7 [0 – 1+] and Hs 578T [0]). Cultured cancer cells were spun onto CellKeep™ slides and stained with ANGLE’s Portrait HER2 IF panel, comprising a nuclear dye, an anti-HER2 antibody, epithelial, mesenchymal and leukocyte markers. Slides were imaged on a BioView Allegro Plus, a platform equipped with artificial intelligence for automated imaging, CTC candidate identification and reporting. The workflow was implemented using samples from 5 MBC patients with known HER2 IHC scores, whose blood was drawn into Streck Cell-Free DNA tubes and processed on ANGLE's Parsortix® instrument, a marker-independent microfluidic device which isolates CTCs based on size and deformability, before being stained with the Portrait HER2 assay. The cohort is being expanded and currently includes three HER2 0 and two HER2 3+ patients as diagnosed by tissue IHC. Results. By observing mean fluorescence intensity (MFI) of each cancer cell line reported to be reflective of each IHC score, thresholds were set to establish a protein scoring system. 95%, 95% and 91% of SKBR3, HCC1954 and SKOV-3, respectively, fell in the 3+ class, 83% of ZR-75-1 fell in the 2+ class, 69% of MCF-7 fell in the 1+ class and 25% and 89% of MCF-7 and Hs 578T, respectively, fell in the 0 class. ≥1 CTC were found in all 5 subjects (mean=405, median=146), with 60% donors presenting mesenchymal CTCs, 20% epithelial CTCs and 20% epithelial and mesenchymal CTCs. HER2+ CTCs were found in both HER2 3+ donors, but not in the HER2 0 donors. HER2+ CTCs from both donors fell in the 3+ class based on MFI, despite one donor receiving Herceptin treatment (1 CTC) and the other being treatment naïve (435 CTCs). Conclusion. This study showed it is possible to establish a HER2 protein scoring system using cultured cancer cell lines stained with the Portrait HER2 assay and demonstrates the potential utility of liquid biopsy in tracking HER2 status. This scoring system will be applied to CTCs isolated from an extended cohort of MBC patients with known tissue biopsy HER2 IHC results to test the robustness of the system and assess concordance of CTC and tissue biopsy scores. FISH will be performed on the samples from MBC patients to confirm results. Citation Format: Alex Young, Laila Vlietinck, Bethan Edwards, Liam Cook, Chassidy Johnson, Mariacristina Ciccioli, Anne-Sophie Pailhes-Jimenez. Development of a scoring system to classify HER2 protein expression in circulating tumor cells through immunofluorescence following isolation using Parsortix® instruments [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A046.

CNSC-62. DIFFERENTIAL SURVIVAL IMPACT OF TRASTUZUMAB DERUXTECAN IN HER2-POSITIVE VERSUS HER2-LOW BREAST CANCER PATIENTS WITH BRAIN METASTASES

Abstract BACKGROUND Brain metastases (BM) in breast cancer (BC) present significant treatment challenges, with varying outcomes based on HER2 expression. There is limited real-world evidence of outcomes with the use of trastuzumab deruxtecan (T-DXd) on survival in patients (pts) with HER2-low and HER2-positive (HER2+) MBC with BM. METHODS We conducted a retrospective cohort study using data from seven US-based health systems within the Guardian Research Network (GRN). We included pts treated with T-DXd from December 2019 to December 2023, classified as HER2-low (IHC 1+ or IHC 2+/HER2 FISH non-amplified) or HER2+ (IHC 3+ or HER2+ with FISH amplified). Survival analysis was performed using Kaplan-Meier curves and the log-rank test. RESULTS 125 pts with BCBM treated with T-DXd were included in the final analysis, of which 70 (56%) were HER2+ and 55 (44%) were HER2-low. The median age at BM diagnosis was 60.5 years (range 21.6 to 87.1 years). HER2 low pts had a higher prevalence of ER+ disease than HER2+ pts (81.9% vs. 55.7%, p=0.01). Most of these pts (≥75%) had received multiple prior lines of therapy. HER2+ pts with BM had a median overall survival (mOS) of 9.3 months (95% CI: 6.79-11.88), significantly longer than 4.3 months (95% CI: 1.89-6.82) in HER2-low pts (p < 0.001). At 6 months, OS for HER2+ pts with BM was 40% compared to 25% in HER2-low pts. At 12 months, OS for HER2+ pts was 20% compared to 10% in HER2-low pts. CONCLUSIONS This study represents the largest real-world evidence to date on the effectiveness of T-DXd in treating BM from breast cancer. HER2+ BCBM exhibited longer mOS and 12-month survival rates than pts with HER2-low disease, suggesting HER2 expression is crucial in determining T-DXd’s effectiveness. Future research should explore combination therapies and identify predictive biomarkers to optimize treatment strategies through clinical trials.

Deep-Learning-Based Approach in Cancer-Region Assessment from HER2-SISH Breast Histopathology Whole Slide Images

Fluorescence in situ hybridization (FISH) is widely regarded as the gold standard for evaluating human epidermal growth factor receptor 2 (HER2) status in breast cancer; however, it poses challenges such as the need for specialized training and issues related to signal degradation from dye quenching. Silver-enhanced in situ hybridization (SISH) serves as an automated alternative, employing permanent staining suitable for bright-field microscopy. Determining HER2 status involves distinguishing between “Amplified” and “Non-Amplified” regions by assessing HER2 and centromere 17 (CEN17) signals in SISH-stained slides. This study is the first to leverage deep learning for classifying Normal, Amplified, and Non-Amplified regions within HER2-SISH whole slide images (WSIs), which are notably more complex to analyze compared to hematoxylin and eosin (H&E)-stained slides. Our proposed approach consists of a two-stage process: first, we evaluate deep-learning models on annotated image regions, and then we apply the most effective model to WSIs for regional identification and localization. Subsequently, pseudo-color maps representing each class are overlaid, and the WSIs are reconstructed with these mapped regions. Using a private dataset of HER2-SISH breast cancer slides digitized at 40× magnification, we achieved a patch-level classification accuracy of 99.9% and a generalization accuracy of 78.8% by applying transfer learning with a Vision Transformer (ViT) model. The robustness of the model was further evaluated through k-fold cross-validation, yielding an average performance accuracy of 98%, with metrics reported alongside 95% confidence intervals to ensure statistical reliability. This method shows significant promise for clinical applications, particularly in assessing HER2 expression status in HER2-SISH histopathology images. It provides an automated solution that can aid pathologists in efficiently identifying HER2-amplified regions, thus enhancing diagnostic outcomes for breast cancer treatment.

Efficacy and safety of RC48-ADC in HER2-positive and HER2-low metastatic breast cancer: a multicenter, real-world study

BackgroundA standard treatment recommendation for third-line and subsequent treatments for advanced HER2-positive breast cancer is still missing, especially for low HER2 expression. Nevertheless, there is evidence that these patients might benefits from antibody-drug conjugates (ADCs) treatment. Therefore, this study aimed to evaluate the clinical efficacy, safety, and factors affecting efficacy of Disitamab Vedotin (RC48) for treating HER2-positive and HER2-low metastatic breast cancer (MBC) in the real-world setting.MethodsA retrospective study at five clinical sites was conducted in China, enrolling MBC patients treated with RC48 from July 01, 2021 and May 31, 2023. Patient demographics, treatment patterns, and adverse events (AEs) were recorded and analyzed.ResultsA total of 154 patients were included: 104 (67.53%) patients with HER2-positive and 50 (32.47%) patients with HER2-low MBC. The median progression-free survival (mPFS) was 5.06 months. The objective response rate (ORR) and disease control rate (DCR) were 36.36% and 68.83%, respectively. HER2-positive patients exhibited a mPFS of 5.93 and an ORR of 41.35%. In contrast, patients with low-HER2 had a mPFS of 4.28 months and an ORR of 26.00%. The most common AEs included neutropenia (54.55%), increased AST (53.25%), leukopenia (51.95%), and fatigue (43.51%), mostly graded mild to moderate (grade 1-2).ConclusionsThis extensive study in China demonstrated that RC48 has excellent therapeutic potential for both HER2-positive and HER2-low MBC with a favorable safety profile. The study also suggests that combination therapy significantly boosts efficacy beyond monotherapy, indicating a promising avenue for future ADC development.

Differentiating HER2-low and HER2-zero tumors with 21-gene multigene assay in 2,295h + HER2- breast cancer: a retrospective analysis.

HER2-positivity is an essential marker for therapeutic decisions, while HER2 expression is heterogenous. In recent years, there has been increasing recognition of a subgroup of breast cancer patients who have low levels of HER2 expression, also known as HER2-low because trastuzumab deruxtecan offers clinical benefit for patients with HER2-low metastatic breast cancer. Despite the growing interest in HER2-low breast cancer, there is limited research on how multigene assays can help differentiate between HER2-low and HER2-negative breast cancer. Among HR + HER2- breast cancer, we compared genomic characteristics between HER2-low and HER2-zero using the 21-gene assay. A retrospective review of clinical records was performed in 2,295 patients who underwent Oncotype DX® test in two hospitals between 2013 and 2020. Patients were classified into two groups as the HER2-zero and HER2-low based on HER2 immunohistochemistry. In cases with HER2 2+, no amplification of HER2 gene was confirmed by silver in situ hybridization. High genomic risk was defined as cases with 21-gene recurrence score (RS) > 25. Multivariable binary logistic-regression analysis was performed. Of these, 944 (41.1%) patients were assigned to the HER2-zero group, while 1351 (58.9%) patients were assigned to the HER2-low group. The average Recurrence Score (RS) was found to be 17.802 in the HER2-zero breast cancer group and 18.503 in the HER2-low group, respectively (p-value < 0.005). When comparing the proportion of high RS between the two groups, the HER2-zero group had a high RS rate of 12.4% (117 out of 944), while the HER2-low group had a high RS rate of 17.0% (230 out of 1351) (p = 0.002). The HER2 score identified by qRT-PCR was 8.912 in the HER2-zero group and 9.337 in the HER2-low group (p < 0.005). In multivariable analysis, HER2-low status was found to be an independent factor for high RS, with an odds ratio of 1.517 (1.172-1.964), independent of ER, PR, and Ki67. Within the subgroup of patients with invasive ductal carcinoma, the high RS rates were 19% in the HER2-low group and 14% in the HER2-zero group. However, when considering all patients, there were no significant differences observed in recurrence-free survival and overall survival between the HER2-low and HER2-zero groups. Within HR + HER2- breast cancer, HER2-low tumors are associated with high RS, especially for histologically invasive ductal carcinoma. A prognostic influence of HER2-low expression among HR + HER2- breast cancer remains as an area that requires further study.

Single-cell sequencing unveils mitophagy-related prognostic model for triple-negative breast cancer

BackgroundTriple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer lacking hormone receptors and HER2 expression, leading to limited treatment options and poor prognosis. Mitophagy, a selective autophagy process targeting damaged mitochondria, plays a complex role in cancer progression, yet its prognostic significance in TNBC is not well understood.MethodsThis study utilized single-cell RNA sequencing data from the TCGA and GEO databases to identify mitophagy-related genes (MRGs) associated with TNBC. A prognostic model was developed using univariate Cox analysis and LASSO regression. The model was validated across multiple independent cohorts, and correlations between MRG expression, immune infiltration, and drug sensitivity were explored.ResultsNine key MRGs were identified and used to stratify TNBC patients into high-risk and low-risk groups, with the high-risk group showing significantly worse survival outcomes. The model demonstrated strong predictive accuracy across various datasets. Additionally, the study revealed a correlation between higher MRG expression levels and increased immune cell infiltration, as well as potential responsiveness to specific chemotherapeutic agents.ConclusionThe mitophagy-related prognostic model offers a novel method for predicting outcomes in TNBC patients and highlights the role of mitophagy in influencing the tumor microenvironment, with potential applications in personalized treatment strategies.

Current status and challenges in HER2 IHC assessment: scoring survey results in Japan.

This study aimed to assess the concordance of human epidermal growth factor receptor 2 (HER2) expression scoring by immunohistochemistry (IHC) among practicing pathologists in Japan, given the challenging nature of scoring and the critical role of HER2 status in breast cancer management. Whole slide images (WSI) from 20 invasive breast cancer cases (1 representative WSI per case) selected to represent a diverse IHC scores and staining patterns were used in an online survey involving seven reference pathologists who established consensus HER2 IHC scores (0 to 3 +) decided by majority interpretation. Participating pathologists nationwide scored the same 20 WSI cases online using the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) 2018 guidelines. Deidentified case metadata were registered in the uPath system. A total of 144 participating pathologists responded. The scoring results of the participating pathologists most commonly agreed with the consensus IHC score, followed by a ± 1 point deviation and no survey responses with > 1 point deviation. The mean percentage of agreement with the consensus score for all 20 cases was 63.4%. In cases where the reference pathologists' scores were discordant, the participating pathologists also showed a lower concordance rate. This study highlighted the current status of HER2 expression scoring by IHC for breast cancer among pathologists in Japan. These findings underscore the challenges in HER2 IHC scoring cases and emphasize the need for improved standardization and training, especially in the evolving landscape of HER2-targeted therapies.

Evidence for Unified Assessment Criteria of HER2 IHC in Colorectal Carcinoma

HER2 expression is an important biomarker for the management of RAS wild-type metastatic colorectal carcinoma (CRC). Immunohistochemistry (IHC) with reflex in situ hybridization (ISH) is accepted as a standard method of assessment, yet there are currently two sets of criteria used to interpret results: the HERACLES criteria, and the My Pathway criteria. The HERACLES criteria require ISH confirmation when IHC staining is 3+ in 10-49% of cells, while the My Pathway criteria mirror those for gastric HER2 assessment and do not recommend ISH confirmation in the previously referenced scenario. We aimed to assess the prevalence of HER2 3+ heterogeneity and its association with ERBB2 copy number amplification (CNA) to evaluate the necessity of ISH testing when IHC staining is 3+ in <50% of cells.Next-generation sequencing (NGS) of DNA (592-gene panel or whole exome sequencing; WES) was performed for 13 208 colorectal carcinoma (CRC) tumors submitted to Caris Life Sciences (Phoenix, AZ). HER2 (4B5) expression was tested by IHC. A subset of tumors was tested for ERBB2 amplification via chromogenic ISH and/or via NGS (copy number amplification [CNA]). X2/Fisher-Exact tests were applied where appropriate, with p-values adjusted for multiple comparisons (p< 0.05).Of 13 208 CRCs with HER2 IHC, 87.4% (11 541/13 208) were negative for HER2 expression (intensity ≤3+ and < 10% tumor-cell staining) and 11.2% (1 473/13 208) demonstrated at least low HER2 expression (1-2+ and ≥10%). Only 1.5% (194/13 208) of all tested tumors were either positive or heterogeneously positive for HER2 overexpression (3+, ≥10%). Of these, 14% (28/194) had heterogenous HER2 overexpression (3+ staining of 10-49% of cells). Among 22 HER2-positive/heterogenous cases with successful ISH testing, 100% (22/22) demonstrated amplification via ISH.Because the classification of tumors as HER2-positive/heterogenous by IHC correlated very closely with ISH positivity, our results suggest that ISH is likely unnecessary for CRCs with 3+ HER2 overexpression in 10-49% of neoplastic cells.

Targeted delivery of Saikosaponin A and doxorubicin via hyaluronic acid-modified ZIF-8 nanoparticles for TNBC treatment: Inhibiting metastasis and reducing cardiotoxicity

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by the absence of estrogen receptors, progesterone receptors, and HER2 expression, making traditional hormone and targeted therapies ineffective. Chemotherapy remains the primary treatment for TNBC; however, it has failed to adequately address the high rates of recurrence and metastasis, underscoring the urgent need for new therapeutic strategies. This study investigates Saikosaponin A (SSA), a compound extracted from traditional Chinese medicine, for its potential to enhance the efficacy of doxorubicin (DOX) chemotherapy while reducing TNBC metastasis and mitigating DOX-induced cardiotoxicity.We first confirmed SSA's cardioprotective effects against DOX-induced cardiotoxicity, highlighting its potential as an adjunctive therapy for TNBC chemotherapy. Subsequently, through network pharmacology analysis, we identified that SSA may inhibit TNBC progression and metastasis by downregulating integrin β3, a key regulatory factor in tumor development. This was further validated through both in vivo and in vitro experiments. To address the poor bioavailability of SSA, we developed a novel drug delivery system utilizing hyaluronic acid (HA)-modified zeolitic imidazolate framework-8 (ZIF-8) nanoparticles for the co-delivery of SSA and DOX. This nano-drug system exhibited excellent stability and high drug-loading capacity, with loading efficiencies of 40.07 % for SSA and 43.07 % for DOX. After 24 h of nano-drug administration, the DOX concentration in the group using the nano-delivery system was 5.01 times higher than control group, demonstrated enhanced tumor-targeting capability. Furthermore, after 14 days of treatment, the tumor volume was reduced by 80.8 % compared to the control group, indicating significantly improved therapeutic efficacy (all P < 0.05).This study systematically evaluates the potential of this dual drug-loaded nanocarrier in improving TNBC treatment, reducing DOX-induced cardiotoxicity, and inhibiting metastasis, offering a novel therapeutic approach that integrates traditional medicine with advanced nanotechnology.

HER2 expression by next-generation sequencing versus immunohistochemistry in uterine serous carcinoma at a major gynecologic oncology referral center in the Southeast

HER2 expression by next-generation sequencing versus immunohistochemistry in uterine serous carcinoma at a major gynecologic oncology referral center in the Southeast

Broussoflavonol F exhibited anti-proliferative and anti-angiogenesis effects in colon cancer via modulation of the HER2-RAS-MEK-ERK pathway

BackgroundA prenylated flavonoid, broussoflavonol F (BFF), was isolated from Macaranga genus with cytotoxicities against various cancer cells, though its underlying mechanisms have not been fully elucidated. HypothesisThis study aimed to investigate the anti-tumor and anti-angiogenesis activities of BFF and its underlying mechanisms in colon cancer. MethodIn the in vitro study, the cytotoxic effects of BFF in human colon cancer HCT-116 and LoVo cells were examined using MTT assay, BrdU assay and colony formation assay. The anti-proliferative effects of BFF in these cells were assessed via cell apoptosis and cell cycle analysis using flow cytometry. The anti-angiogenesis effects of BFF in human endothelial HEMC-1 cells were also detected using scratch wound healing assay and tube formation assay. While the in vivo effects of BFF in colon cancer were further examined in zebrafish embryos and HCT116 tumor-bearing mice. The underlying mechanisms of BFF were predicted using network pharmacology analysis, and Western blotting was performed to validate both in vitro and in vivo results. ResultsBFF exhibited cytotoxicities on 5 colon cancer cell lines, as well as anti-proliferative activities via inducing apoptosis and cell cycle arrest at the G0/G1 phase in HCT116 and LoVo cells. BFF at 1.25-5 µM also suppressed cell proliferation in these two colon cancer cell lines by downregulating HER2, RAS, p-BRAF, p-MEK and p-Erk protein expressions. In addition, BFF at 2.5-5 µM could significantly decrease the length of subintestinal vessels of zebrafish embryos through decreasing mRNA expressions of NRP1a, PDGFba, PDGFRb, KDR, FLT1 and VEGRaa. Besides, BFF exhibited anti-angiogenesis activity via inhibiting cell proliferation, motility and tube formation in HMEC-1 cells. Furthermore, intraperitoneal administration of BFF (10 mg/kg) suppressed tumor growth and decreased the expression of tumor proliferation marker Ki-67 and angiogenesis marker CD31 in the tumor tissues in HCT116 tumor-bearing mice. BFF treatment could also significantly decrease expressions of RAS, p-BRAF, p-MEK and p-Erk in the tumor section, which are consistent with the in vitro results. ConclusionsThis study revealed the anti-tumor and anti-angiogenesis effects of BFF in colon cancer. This is the first report of the in vitro and in vivo anti-proliferative activity of BFF in colon cancer through regulating the HER2-RAS-MEK-ERK pathway. These findings further support the research development of BFF as an anti-cancer agent in colon cancer.

Molecular and Clinicopathologic Characterization of HER2-overexpressed Squamous Cell Carcinoma of the Cervix.

HER2 amplification in cervical cancer has been associated with worse clinical prognosis and a potential favorable response to HER2 inhibitors. Immunohistochemistry for the HER2 receptor is a universally accepted surrogate test for HER2 amplification, but no standardized scoring system currently exists for cervical carcinomas. In this study, we investigated HER2 overexpression in cervical squamous cell carcinoma and correlated it with HER2 amplification using fluorescence in situ hybridization (FISH) and molecular methods. Seventy-two cases of human papillomavirus-associated cervical cancer were retrospectively reviewed, and at least 2 representative tumor sections were stained for HER2. HER2 scoring was performed using the 2018 American Society of Clinical Oncology/College of American Pathologist breast cancer criteria, and cases with equivocal (2+) to positive (3+) expression were analyzed for HER2 amplification using FISH and next-generation sequencing. The average patient age was 50yrs (range: 27-85yr), with most patients being African American (73.6%) and diagnosed at FIGO stage I (65.3%). Nineteen (26.4%) had equivocal HER2 expression and 4 (5.5%) showed positive expression. Three of the 4 cases with positive expression had enough tumors for FISH, and all 3 were amplified. Three cases with equivocal expression showed HER2 polysomy on FISH, and none showed HER2 amplification. Late clinical stage, high tumor grade, and regional lymph node metastasis were significantly correlated with HER2 overexpression and HER2 amplification. Next-generation sequencing of the 3 HER2-amplified tumors showed amplification of various genes, including CD274, JAK2, BIRC3, and ERBB2, and a PIK3CA missense mutation. In summary, HER2 immunohistochemistry is a reliable predictive marker of HER2 amplification in cervical cancer.

A Comparison Between Immunohistochemistry and mRNA Expression to Identify Human Epidermal Growth Factor Receptor 2–Low Breast Cancer

Context.— Breast cancers (BCs) with low levels of human epidermal growth factor receptor 2 (HER2) expression (HER2-low) have become a targetable subset because of novel antibody-drug conjugates. HER2 immunohistochemistry (IHC) is the recommended assay for HER2 classification but is associated with limited interobserver agreement concerning HER2-low identification. Objective.— To investigate whether mRNA expression quantified via quantitative reverse transcription–polymerase chain reaction (RT-qPCR) could serve as a valuable complementary and more objective method to identify HER2-low BCs. Design.— We selected all cases from a previously published interobserver study, which included 105 needle biopsies from HER2 nonamplified BC cases. HER2 IHC was evaluated by 16 pathologists. For the current study, mRNA was extracted from microdissected invasive tumor cells. RT-qPCR was performed for quantitative evaluation of HER2, using the cutoff values of the MammaTyper assay. We compared the mRNA expression levels with the IHC scores of the majority agreement (IHC 0, IHC &amp;gt;0, &amp;lt;1+ [ultralow], 1+, 2+) and the following HER2 subcategories: HER2 0/ultralow and HER2-low (IHC 1+ and 2+/fluorescence in situ hybridization negative). Results.— In total, 88 nonamplified HER2 cases could be analyzed. Based on IHC, 17 cases were HER2 0/ultralow and 71 were HER2-low. The mean rank HER2 mRNA level was significantly higher in HER2-low cases than in the HER2 0/ultralow group (P &amp;lt; .001). However, 10 of 17 HER2 0/ultralow cases by IHC (58.8%) were classified as HER2-low by MammaTyper, 2 of 71 cases (2.8%) were HER2-low by IHC and HER2 0/ultralow by MammaTyper, and 2 (2.8%) were HER2-low by IHC and HER2-positive by RP-qPCR. Conclusions.— Our findings indicate a strong agreement between mRNA expression quantified by RT-qPCR and HER2 IHC scores, although there was a substantial proportion of discordant HER2 results between both methods owing to overestimation of HER2 expression by MammaTyper compared to IHC. Future large-scale trials should determine which technique is best associated with clinical outcome.

64Cu]Cu-NOTA-Trastuzumab and [89Zr]Zr-DFO-Trastuzumab in Xenografts with Varied HER2 Expression.

Positron emission tomography (PET) has potential as a complementary technique to biomarker analysis, especially for human epidermal growth factor receptor 2 (HER2)-expressing tumors characterized by high heterogeneity. In this study, zirconium-89 (89Zr) and copper-64 (64Cu) labeled trastuzumab were employed to monitor varying levels of tumoral HER2 expression. Additionally, we studied the use of the cholesterol-depleting lovastatin as a pharmacological approach to enhance cell-surface HER2 expression in tumors with moderate to low HER2 levels, aiming to increase antibody accumulation in these tumor types. Both 89Zr- and 64Cu-labeled trastuzumab effectively monitor HER2 expression levels in xenografts exhibiting varying HER2 expression. No significant difference in tumor uptake was observed between 89Zr- or 64Cu-labeled trastuzumab, and tumor uptake for both radioimmunoconjugates positively correlated with HER2 protein levels. These findings underscore the potential of PET to monitor HER2 protein levels across heterogeneous tumors. Furthermore, our results suggest that further optimization of statin dosing and timing could offer a promising strategy to enhance trastuzumab accumulation in HER2-high, HER2-moderate, and HER2-low tumors.

Exploring lipidomic profiles and their correlation with hormone receptor and HER2 status in breast cancer.

Dysregulated lipid metabolism promotes the progression of various cancer types, including breast cancer. The present study aimed to explore the lipidomic profiles of patients with breast cancer, providing insights into the correlation between lipid compositions and tumor subtypes characterized by hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status. Briefly, 30 patients with breast cancer were categorized into four groups based on their HR and HER2 status: HR+ no HER2 expression (HER2-0), HR+ HER2-low; HR+ HER2-positive (pos) and HR- HER2-pos. The lipidomic profiles of these patients were analyzed using high-throughput liquid chromatography-mass spectrometry. The data were processed through principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA) and random forest (RF) classification to assess the lipidomic variations and significant lipid features among these groups. The profiles of the lipids, particularly triglycerides (TG) such as TG(16:0-18:1-18:1)+NH4, were significantly different across the groups. PCA and PLS-DA identified unique lipid profiles in the HR+ HER2-pos and HR+ HER2-0 groups, while RF highlighted phosphatidylinositol-3,4,5-trisphosphate(21:2)+NH4 as a crucial lipid feature for accurate patient grouping. Advanced statistical analysis showed significant correlations between lipid carbon chain length and the number of double bonds within the classifications, providing insights into the role of structural lipid properties in tumor biology. Additionally, a clustering heatmap and network analysis indicated significant lipid-lipid interactions. Pathway enrichment analysis showed critical biological pathways, such as the 'Assembly of active LPL and LIPC lipase complexes', which has high enrichment ratio and statistical significance. In conclusion, the present study underscored that lipidomic profiling is crucial in understanding the metabolic alterations associated with different breast cancer subtypes. These findings highlighted specific lipid features and interactions that may serve as potential biomarkers for breast cancer classification and target pathways for therapeutic intervention. Furthermore, advanced lipidomic analyses can be integrated to decipher complex biological data, offering a foundation for further research into the role of lipid metabolism in cancer progression.

A Rare Case of Triple-Negative Breast Cancer with RAD51D Gene Mutation

Background: The heterogeneity of breast cancer (BC) subtypes poses a significant challenge, with carcinogenesis involving multiple stages and genes, including proto-oncogenes, tumor suppressor genes, and DNA repair genes. Next-generation sequencing has expanded access to multigene panels, such as RAD51 paralogs, which increase the risk of ovarian cancer and possibly triple-negative (TN) BC. Case presentation: We present a rare case of a 45-year-old woman with TNBC and a RAD51D gene mutation. Mammography and breast ultrasonography revealed an irregular, 30 mm hypoechoic area and dystrophic calcifications in the right breast. Immunohistochemistry showed a lack of expression of ER, RP, HER-2, and P53, with 50% of neoplastic cell nuclei positive for Ki-67. Next-generation sequencing revealed a mutation in RAD51D and MUYTH genes. The patient underwent partial mastectomy, chemotherapy, and prophylactic mastectomy. Conclusion: Genetic analysis is crucial for identifying specific mutations contributing to TNBC development. Current preventive interventions primarily address BRCA1 and BRCA2 mutations, following established guidelines.

Comparing the Sensitivity of HER2 Epitope Detection of HercepTest mAb pharmDx (Dako Omnis, GE001) and Ventana PATHWAY Anti-HER-2/neu (4B5) Using IHC Calibrators.

Accurate assessment of HER2 expression levels is paramount for determining eligibility for targeted therapies. HER2 immunohistochemistry provides a semiquantitative measurement of HER2 protein overexpression. Historically, little focus has been on the lower end of the HER2 expression range. The advent of novel therapeutic molecules that require fewer membrane epitopes to be effective has prompted a reevaluation of the current immunohistochemistry testing protocols, with special emphasis on the detection limit. Here, we have used Boston Cell Standards technology to determine the sensitivity of 2 commercially available HER2 immunohistochemistry assays, including a lower limit of detection.

Immunomodulatory effects of trastuzumab deruxtecan through the cGAS-STING pathway in gastric cancer cells

Although the efficacy of trastuzumab deruxtecan (T-DXd) against HER2-positive gastric cancers (GCs) has driven its clinical application, the precise mechanisms governing its immunomodulatory role remain unclear. In this study, we examined the immune-related mechanisms of action of T-DXd in GC cells. T-DXd exhibited potent antitumor effects in GC cells across diverse HER2 expression levels by inducing DNA damage and apoptosis. Activation of the DNA damage response by T-DXd led to increased PD-L1 expression. RNA-Seq analysis revealed that T-DXd modulated immune-related pathways, resulting in the upregulation of genes associated with inflammation and IFN signaling. Importantly, T-DXd activated the cGAS-STING pathway, inducing an IFN-I response in HER2-positive GC cells. Furthermore, T-DXd activated dendritic cells via the cancer cell-intrinsic cGAS-STING-IFN axis and enhanced PBMC-mediated tumor cell killing by activating CD8+ T cells. These findings provide valuable insights into the role of the cytosolic DNA sensing pathway in the action of T-DXd and offer a compelling rationale for combining T-DXd with immune checkpoint blockade therapies in GC treatment.

Trastuzumab Duocarmazine in Pretreated Human Epidermal Growth Factor Receptor 2-Positive Advanced or Metastatic Breast Cancer: An Open-Label, Randomized, Phase III Trial (TULIP).

Human epidermal growth factor receptor 2 (HER2)-targeted therapy is standard of care for HER2-positive (HER2+) breast cancer, but most patients develop progressive disease with persistent HER2 expression. No definitive treatment guidance currently exists beyond second line. Trastuzumab duocarmazine (T-Duo) is a third-generation, HER2-targeted antibody-drug conjugate that demonstrated efficacy and acceptable safety in phase I studies of heavily pretreated patients with HER2+/HER2-low breast cancer. In this open-label, randomized, phase III trial, T-Duo was compared with physician's choice (PC) in patients with unresectable locally advanced/metastatic HER2+ breast cancer with progression during/after ≥2 HER2-targeted therapies or after trastuzumab emtansine (T-DM1). The primary endpoint was progression-free survival (PFS) by blinded independent central review. In total, 437 patients were randomly assigned 2:1 to T-Duo (n = 291) or PC (n = 146). The median age was 56.0 years (range, 24-86); most patients (93.6%) had metastatic disease. The median time from diagnosis of metastatic disease to trial entry was 3.5 years; the median number of prior HER2-targeted therapies in metastatic setting was three. The median PFS was 7.0 months (95% CI, 5.4 to 7.2) with T-Duo versus 4.9 months (95% CI, 4.0 to 5.5; hazard ratio [HR], 0.64 [95% CI, 0.49 to 0.84]; P = .002) with PC. PFS benefit was maintained across most predefined subgroups. The median overall survival (first analysis) was 20.4 (T-Duo) versus 16.3 months (PC; HR, 0.83 [95% CI, 0.62 to 1.09]; P = .153). Objective response rate was 27.8% (T-Duo) versus 29.5% (PC); other efficacy end points-clinical benefit rate, duration of response, and reduction in target lesion measurement-tended to favor T-Duo. Grade ≥3 treatment-emergent adverse events occurred in 52.8% (T-Duo) versus 48.2% (PC). Treatment with T-Duo was manageable, but tolerability was affected by prevalent ocular toxicity, leading to a higher discontinuation rate in the T-Duo arm. T-Duo significantly reduced the risk of progression in patients with advanced HER2+ breast cancer who have progressed during/after ≥2 HER2-targeted therapies or after T-DM1.

Efficacy and safety of dual blockade of HER2 and PD-1 in patients with HER2-positive gastric cancer: a retrospective, multicentre study

Human epidermal growth factor receptor 2 (HER2) expression is one of the most important pathological characteristics of gastric cancer. The positive rate of HER2 expression in patients with gastric cancer is approximately 20%. The phase III Keynote-811 study revealed that anti-HER2 and anti-PD-1 therapy combined with chemotherapy could significantly improve the objective response rate as first-line treatment in patients with HER2-positive advanced gastric cancer. In the present study, we aimed to evaluate the efficacy of combination therapy with trastuzumab and PD-1 inhibitors in patients with advanced HER2-positive gastric cancer in a real-world setting. Seventy-two HER2-positive gastric cancer patients from three hospitals in China were retrospectively reviewed. These patients were treated with trastuzumab plus one anti-PD-1 agent with or without chemotherapy. The overall response rate, progression-free survival and overall survival were assessed according to the Response Evaluation Criteria in Solid Tumours (RECIST 1.1). From January 2018 to October 2021, 72 patients with HER2-positive gastric cancer received trastuzumab and a PD-1 inhibitor with or without chemotherapy as neoadjuvant chemotherapy, first-line therapy, second-line therapy or salvage therapy. The ORR was 54.2% for all patients and 79.4% for previously untreated patients. The median PFS and median OS were 10 months (95% CI: 8–13 months) and 26.1 months (95% CI: 18.5-NA months), respectively, for all patients. Grade 3 adverse effects occurred in approximately 25% of patients. Immune-related adverse effects occurred in approximately 12.5% of patients. Trastuzumab and PD-1 inhibitor combination therapy with or without chemotherapy achieved satisfactory survival outcomes in patients with HER2-positive gastric cancer with acceptable safety.