HER2 Gene Amplification Research Articles

Survival outcomes for HER2-low breast cancer: Danish national data.

We investigated the prognosis of breast cancer (BC) with low expression of human epidermal growth factor receptor 2 (HER2), as previous studies have found varying impacts on survival of HER2-low BC compared with HER2 0 BC (HER2 IHC score of 0). HER2-low is defined as a score of 1+ or 2+ in an immunohistochemical (IHC) assay without HER2 gene amplification. Patients with HER2 0 or HER2-low BC from the national Danish Breast Cancer Group database were examined by multivariable survival analysis in a retrospective noninterventional investigation. Patients were grouped as either HER2 0 or HER2-low. The primary endpoint was time to recurrence (TR), and the secondary endpoints were overall survival (OS) and distant recurrence-free interval (DRFI). 41,610 patients were included (12,981 with HER2 0 BC and 28,629 with HER2-low BC). HER2-low BC was associated with a lower risk of recurrence (hazard ratio [HR]: 0.92, p = 0.03). Regarding secondary endpoints, HER2-low disease was linked to improved overall OS (HR: 0.94, p = 0.02). No statistically significant effect of HER2-low was found for DRFI, along with no differential effect of HER2-low according to estrogen receptor (ER) status. HER2-low BC was found to show an improved HR for OS and DRFI compared with HER2 0 BC; however, further studies are need to establish whether it represents a separate biological entity.

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

BackgroundHER2-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.MethodsA 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.ResultsOf 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.ConclusionWithin 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.

Review of In Situ Hybridization (ISH) Stain Images Using Computational Techniques.

Recent advancements in medical imaging have greatly enhanced the application of computational techniques in digital pathology, particularly for the classification of breast cancer using in situ hybridization (ISH) imaging. HER2 amplification, a key prognostic marker in 20-25% of breast cancers, can be assessed through alterations in gene copy number or protein expression. However, challenges persist due to the heterogeneity of nuclear regions and complexities in cancer biomarker detection. This review examines semi-automated and fully automated computational methods for analyzing ISH images with a focus on HER2 gene amplification. Literature from 1997 to 2023 is analyzed, emphasizing silver-enhanced in situ hybridization (SISH) and its integration with image processing and machine learning techniques. Both conventional machine learning approaches and recent advances in deep learning are compared. The review reveals that automated ISH analysis in combination with bright-field microscopy provides a cost-effective and scalable solution for routine pathology. The integration of deep learning techniques shows promise in improving accuracy over conventional methods, although there are limitations related to data variability and computational demands. Automated ISH analysis can reduce manual labor and increase diagnostic accuracy. Future research should focus on refining these computational methods, particularly in handling the complex nature of HER2 status evaluation, and integrate best practices to further enhance clinical adoption of these techniques.

Evaluation of HER2 immunohistochemistry-positive and immunohistochemistry-negative FISH amplification breast cancers using next-generation sequencing

Abstract Objectives In this study, we aimed to assess the concordance between HER2 positivity, defined as scores of 2+ or 3+ by immunohistochemistry (IHC), and HER2 gene amplification results obtained by fluorescence in situ hybridization (FISH) and gene panel testing (GPT). Methods A total of 45 breast cancer patients with sufficient biopsy, breast-conserving surgery, or mastectomy specimens collected between 2018 and 2024 at Hokuto Hospital were included in the study. HER2 status was defined as HER2+ in cases with scores of 3+ on IHC staining, HER2-FISHamp in cases with scores of 2+ on IHC staining plus FISH amplification. FISH amplification was defined as a ratio of HER2 to the amplification of the chromosome 17 centromere ≥2.0. Next-generation sequencing (NGS) for these genes was conducted using MiSeq. The criterion for ERBB2 amplification requires gene amplification of more than 2 standard deviations (SD) above the average of the panel genes and CN ≥4. Results HER2+ correlated with the presence of NGS amplification of ERBB2 (p&lt;0.001). NGS amplification was significantly more detectable in HER2+ than in HER2-FISHamp. HER2-FISHamp correlated with larger tumor size (p=0.009) and the presence of lymph node metastases (p&lt;0.001). No correlations were observed between the HER2 status and other parameters such as age, histological grade, stage histological type, recurrence, treatment response evaluation, and breast cancer mortality. Conclusions To achieve a comprehensive diagnosis, it is crucial to integrate GPT findings with other diagnostic approaches and to have a though understanding of the characteristics and limitations of each method.

Protein Expression, Amplification, and Mutation of HER2 Gene in Canine Primary Pulmonary Adenocarcinomas: Preliminary Results.

Recently, human epidermal growth factor receptor 2 (HER2) has emerged as a therapeutic target of interest for non-small-cell lung cancer in humans. The role of HER2 in canine pulmonary adenocarcinomas is poorly documented. To address this gap, this study employed three methodologies: immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and next-generation sequencing (NGS) to investigate the protein expression, gene amplification, and mutation of HER2 in 19 canine primary pulmonary adenocarcinomas. By IHC, 3 out of 19 cases were overexpressed 3+, 6 were 2+, and 10 were negative. With FISH, 2 cases were amplified (12.5%), 3 were inadequate for the analyses, and the others were non-amplified. With NGS, seven cases were inadequate. All other cases were wild-type, except for one IHC 3+ case, which was amplified with FISH and with a specific mutation already described in human pulmonary adenocarcinoma, V659E. This mutation is probably sensitive to tyrosine kinase inhibitory drugs. These results are similar to those in human medicine and to the few data in the literature on canine lung carcinomas; the presence of 12.5% of amplified cases in dogs lays the foundation for future targeted drugs against HER2 alterations.

Epithelial-Mesenchymal Transition Indexes in Triple-Negative Breast Cancer Progression and Metastases.

Background Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer characterized by the lack of expression of estrogen and progesterone receptors and the absence of HER2 protein overexpression or gene amplification. How TNBC becomes so aggressive at the molecular level is not yet fully understood. The epithelial-mesenchymal transition (EMT) has been increasingly recognized as playing a pivotal role in cancer progression and metastasis. This study aimed to elucidate the connection between TNBC progression with EMT-related markers, including vimentin, beta-catenin, and E-cadherin. Methodology Rigorous immunohistochemical analysis was employed to assess the expression of vimentin, beta-catenin, and E-cadherin in primary tumors, tumor buds, and lymph node metastases (LNMs) from 137 cases with an invasive ductal carcinoma triple-negative phenotype diagnosed between 2018 and 2024. The EMT index, which was especially important in our work, is the sum of vimentin and beta-catenin expression divided by that of E-cadherin. Estimated Pearson correlation, multiple linear regression, and Kruskal-Wallis tests were used to determine the relationships of the EMT index with tumor buds and tumor-infiltrating lymphocytes (TILs). Results Vimentin highly correlated within separate regions of interest with Pearson correlation ranging from 0.90 to 0.92 (p < 0.001). Strong negative correlations between E-cadherin and vimentin (r = -0.81 to - 0.89, p < 0.001) showed its role in preserving the epithelial phenotype. The presence of tumor buds, aggregates, or clusters of cancer cells shed from the primary tumor mass invading the connective tissue showed very strong associations with the EMT index (r = 0.91, p < 0.001). Its presence is suggestive of aggressive disease and may identify a high-risk subpopulation that may benefit from more active surveillance or adjuvant treatment. Similarly, TILs correlated inversely with the EMT index (r = -0.90, p < 0.001). The most significant predictor of the EMT index, i.e., vimentin, had a model R-squared value of 1.000 in the regression analysis. Conclusions This study brings to light the importance of EMT-related markers in TNBC progression, with special emphasis on tumor buds as possible prognostic indicators for aggressive disease. The negative correlation of TILs with the EMT index indicates that an effective immune response could antagonize EMT-mediated tumor progression. These results suggest that EMT-based treatments in TNBC should be designed from a multimarker perspective by including interactions among several markers to optimize predictions and therapeutics. The results hold the potential to set future research directions and actionable outcomes that could influence clinical utility in the battle against TNBC.

Systematic assessment of HER2 status in ductal carcinoma in situ of the breast: a perspective on the potential clinical relevance

In many countries, hormone receptor status assessment of ductal carcinoma in situ (DCIS) is routinely performed, as hormone receptor-positive DCIS patients are eligible for adjuvant anti-hormonal treatment, aiming to reduce the ipsilateral and contralateral breast cancer risk. Although HER2 gene amplification and its associated HER2 protein overexpression constitute a major prognostic and predictive marker in invasive breast carcinoma, its use in the diagnosis and treatment of DCIS is less straightforward. HER2 immunohistochemistry is not routinely performed yet, as the role of HER2-positivity in DCIS biology is unclear. Nonetheless, recent data challenge this practice. Here, we discuss the value of routine HER2 assessment for DCIS. HER2-positivity correlates strongly with DCIS grade: around four in five HER2-positive DCIS show high grade atypia. As morphological DCIS grading is prone to interobserver variability, HER2 immunohistochemistry could render grading more robust. Several studies showed an association between HER2-positive DCIS and ipsilateral recurrence risk, albeit currently unclear whether this is for overall, in situ or invasive recurrence. HER2-positive DCIS tends to be larger, with a higher risk of involved surgical margins. HER2-positive DCIS patients benefit more from adjuvant radiotherapy: it substantially decreases the local recurrence risk after lumpectomy, without impact on overall survival. HER2-positivity in pure biopsy-diagnosed DCIS is associated with increased upstaging to invasive carcinoma after surgery. HER2 immunohistochemistry on preoperative biopsies might therefore provide useful information to surgeons, favoring wider excisions. The time seems right to consider DCIS subtype-dependent treatment, comprising appropriate local treatment for HER2-positive DCIS patients and de-escalation for hormone receptor-positive, HER2-negative DCIS patients.

Image analysis for bright-field HER2 in situ hybridization: validation for clinical use.

The aim of the present study was to develop and validate a quantitative image analysis (IA) algorithm to aid pathologists in assessing bright-field HER2 in situ hybridization (ISH) tests in solid cancers. A cohort of 80 sequential cases (40 HER2-negative and 40 HER2-positive) were evaluated for HER2 gene amplification with bright-field ISH. We developed an IA algorithm using the ISH Module from HALO software to automatically quantify HER2 and CEP17 copy numbers per cell as well as the HER2/CEP17 ratio. We observed a high correlation of HER2/CEP17 ratio, an average of HER2 and CEP17 copy number per cell between visual and IA quantification (Pearson's correlation coefficient of 0.842, 0.916, and 0.765, respectively). IA was able to count from 124 cells to 47,044 cells (median of 5565 cells). The margin of error for the visual quantification of the HER2/CEP17 ratio and of the average of HER2 copy number per cell decreased from a median of 0.23 to 0.02 and from a median of 0.49 to 0.04, respectively, in IA. Curve estimation regression models showed that a minimum of 469 or 953 invasive cancer cells per case is needed to reach an average margin of error below 0.1 for the HER2/CEP17 ratio or for the average of HER2 copy number per cell, respectively. Lastly, on average, a case took 212.1s to execute the IA, which means that it evaluates about 130 cells/s and requires 6.7s/mm2. The concordance of the IA software with the visual scoring was 95%, with a sensitivity of 90% and a specificity of 100%. All four discordant cases were able to achieve concordant results after the region of interest adjustment. In conclusion, this validation study underscores the usefulness of IA in HER2 ISH testing, displaying excellent concordance with visual scoring and significantly reducing margins of error.

HER2 status results in an unstable switch from primary to recurrent breast cancer.

Accurately distinguishing HER2-2+ tumors from HER2-0/1+ tumors via immunohistochemistry (IHC) is still very challenging. HER2 IHC 2+ is considered to indicate moderate expression and is easier to distinguish, with more reliable results in previous and current clinical practice. We focused on HER2-2+ patients and evaluated the switch in HER2 status between primary and paired recurrent disease patients to evaluate the discordance of HER2-2+ expression. We included patients who were HER2-2+ of primary or rebiopsy tumor samples, to evaluate the evolution of HER2-2+ expression. In the cohort with a total of 159 patients with HER2-2+ expression in either primary tumor or locoregional/distant metastasis samples, 44.0% had HER2-2+ in primary tumor and 88.8% in recurrent disease. Among patients with primary and recurrent HER2-2+ breast cancers, 18.5% and 15.2% of the patients, respectively, had HER2 gene amplification via ISH. The overall rate of discordance in HER2 IHC results was 67.1%. Among primary HER2-2+ patients, 74.6% were maintained in the HER2-2+ cohort at the recurrence. The discordance was mostly driven by patients switching from HER2-2+ to HER2-1+ (64.7%). Among HER2-2+ recurrent patients, discordance in the IHC results was mostly driven by switching from HER2-0 to HER2-2+ (47.1%). When HER2-low was added to the analysis, the overall rate of HER2 discordance was 40.4%. The proportion of patients with discordant HER2 expression was significantly greater among HR-positive patients than negative patients (44.1% vs. 21.7%, p=0.062). HER2 expression in primary and recurrent breast cancer samples was highly unstable. Discordance was more frequently observed in the HR-positive population.

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

BackgroundThe aim of this study was to elucidate the histogenesis and genetic underpinnings of fibromatosis-like undifferentiated gastric carcinoma (FLUGC), a rare pathological entity.MethodThrough 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.ResultsOf 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 β-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.ConclusionThe 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.

HER2-negative or low expression as an unfavorable prognostic factor in patients with stage I/II uterine carcinosarcoma.

Uterine carcinosarcoma (UCS) is uncommon high-grade endometrial cancer with limited treatment options. We evaluated the prognostic significance of human epidermal growth factor receptor 2 (HER2) expression and HER2 gene amplification within large cohorts of UCS, and clarify clinicopathologic characteristics of HER2-low UCS. We examined HER2 protein expression in 148 patients of UCS using in vivo diagnostic HER2 immunohistochemistry (IHC) kits and HER2 gene amplification using fluorescence in situ hybridization (FISH) in 72 patients. HER2 IHC score was evaluated according to the latest American Society of Clinical Oncology/College of American Pathologists criteria for gastric cancer, which was negative in 41 patients, low expression of 1+ was observed in 57 patients, and HER2 high expression was observed in 50 patients (2+ in 38 and 3+ in 12 patients). There was no significant statistical difference in clinicopathological characteristics based on HER2 protein expression status. HER2 negative and low expression compared to high expression revealed poor overall survival in stage I/ II. The concordance between IHC and FISH results were relatively low compared to other cancer types (HER2 IHC score 1+, 2+, and 3+ were 5%, 15%, and 50%), and combining these results was not efficient as a prognostic factor in UCS. In contrast, the HER2 IHC score alone was a prognostic factor in stage I/II UCS. HER2 low group did not show specific clinicopathologic features. Since the HER2 IHC score low in advanced UCS is a predictive factor, stratification of UCS using HER2 IHC score for HER2 IHC score low group and developing adjuvant therapy may be proposed in the near future.

Significance of concurrent evaluation of HER2 gene amplification and p53 and Ki67 expression in gastric cancer tissues.

The primary objective of this study is to explore the significance of concurrent evaluation of HER2 gene amplification and p53 and Ki67 expression in gastric cancer tissues. Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) methodologies were used to detect HER2 gene amplification, as well as the expression levels of HER2, p53, and Ki67 proteins, across a group of 78 gastric cancer cases. The expression rate of the HER2 protein was determined to be 43.6% (34/78), with 17.9% (14/78) categorized as HER2 protein 3 + , 14.1% (11/78) as HER2 protein 2 + , and 11.5% (9/78) as HER2 protein 1 + . Using FISH technology, the HER2 gene amplification rate was identified as 19.2% (15/78), including 3 cases of HER2 gene cluster amplification, 5 cases of large granular amplification, 4 cases of punctate amplification, and 3 cases of high polysomy. The positive rate of p53 in gastric cancer cells was 52.6% (41/78), with 62.8% (49/78) of patients exhibiting a ki67 proliferation index ≤ 30, and 37.2% (29/78) accounting for a ki67 proliferation index > 30. The expression rates of the HER2 gene, p53, and ki67 in gastric cancer tissues were significantly associated with both gastric cancer staging and lymph node metastasis (P < 0.05). The HER2 gene amplification rate and gene copy number exhibit a positive correlation with the expression rates of p53 and ki67. Combining these assessments can provide crucial insights into the assessment of metastatic potential, disease progression, and prognosis of gastric tumor cells. This holds paramount importance in steering the formulation of individualized treatment strategies.

Targetable ERBB2/HER2 Mutations in Gynecologic Malignancies: Clinicopathological, Immunohistochemical, and Molecular Correlations.

Targeted anti-HER2 therapy has been recently added to the standard treatment recommendations in endometrial serous carcinoma. Current eligibility requires testing for HER2 overexpression and/or gene amplification by immunohistochemistry and by fluorescence in situ hybridization. However, clinical trials have also demonstrated the efficacy of anti-HER2 drugs against activating ERBB2/HER2 mutations in a variety of solid tumor types, and fam-trastuzumab deruxtecan is now approved by the US Food and Drug Administration for HER2-mutant non-small cell lung cancer. This study aimed at evaluating the detailed clinical, histomorphological, immunohistochemical, and molecular characteristics of gynecologic malignancies with ERBB2/HER2 mutations. We identified 16 tumors with 19 ERBB2/HER2 mutations in our departmental archives: 11 endometrial primaries, 2 endocervical adenocarcinomas, 1 ovarian mucinous adenocarcinoma, 1 tubo-ovarian undifferentiated carcinoma, and 1 high-grade endometrioid adenocarcinoma of Mullerian origin. ERBB2/HER2 mutations most often involved the tyrosine kinase domain (52.6%), and the most frequent specific mutation was R678Q (31.6%), involving the juxtamembrane domain. More than half (54.5%) of endometrial carcinomas and half of all tumors were MMR-deficient, resulting from MSH6 loss in all but 2 tumors. None of the tumors (0%) were POLE-mutated, while 18.8% were TP53-mutated. HER2 IHC was negative (score 0 or 1+) in 12 tumors (67%) and equivocal (score 2+) in 4 tumors (33%), whereas none of the tumors were scored as HER2 3+. Score 2+ was associated with R678Q, L755S, I767M mutations, and ERBB2/HER2 rearrangement with a breakpoint in exon 23. Concurrent ERBB2/HER2 amplification was identified in 2 endometrial carcinomas, with HER2/CEP17 ratios of 3.1 and 3.5. We also queried the cBioportal database, which revealed 70 ERBB2/HER2-mutant gynecologic tumors with a total of 77 ERBB2/HER2 mutations, most often involving the active site of the tyrosine kinase domain (n=36; 46.8%), and the most common specific mutation was S310F (n=20; 26%), located in the extracellular domain. Our results provide important details regarding the clinicopathological and molecular associations of potentially actionable ERBB2/HER2 mutations in endometrial carcinoma and other gynecological cancer types and contribute to addressing clinical treatment needs and improving pathology testing recommendations in the future.

HER2-neu Expression and Survival in Colorectal Cancer in the South of Egypt; Immunohistochemistry and Genetic Study.

Colorectal cancer (CRC) is a major public health problem and one of leading cancer related death all over the world. One of the prognostic parameters that play a role in different types of cancer is HER2. However, the role of HER2 in CRC and its relation with clinicopathological features and survival is conflicting. We hypothesize that HER2 has different patterns of expression in CRC which may affect the prognosis of patients. We studied sixty specimens of colorectal carcinoma for HER2 immunohistochemistry and gene amplification and correlate it with clinicopathological features and patients` survival. Our data showed that negative HER2 expression was statistically associated with female gender (P = 0.010) and low & intermediate tumor budding (P = 0.030). There was a statistically significant relation between HER2 IHC and HER2 FISH amplification (P=0.000). Although neither HER2 immunoexpression and FISH amplification showed significant relation with overall survival nor disease free survival, HER2 amplified CRCs tended to have a worse survival compared with negative CRCs (40 months versus 50 months). The presence of male gender, lymphovascular invasion, nodal metastasis and distant metastasis (P = 0.013, 0.006, 0.006 and 0.000 respectively) were significantly statistically associated with poor overall survival. The presence of tumor grade III and high tumor budding (P = 0.035 and 0.007 respectively) were significantly statistically associated with shorter disease free survival. Our results showed that HER2 IHC 3+ staining is highly predictive of HER2 gene amplification in colorectal carcinomas. There is a tendency towards poorer prognosis in amplified HER2 CRC cases.

IAM1363-01: A phase 1/1b study of a selective and brain-penetrant HER2 inhibitor for HER2-driven solid tumors.

TPS3186 Background: HER2 activation promotes carcinogenesis, prompting the development of HER2-directed therapies in cancers with HER2 alterations. There is a critical need for novel agents to treat HER2-driven cancers, as current inhibitors display significant toxicity and lack efficacy against certain mutations. IAM1363 (formerly IAM-H1 and ENT-H1) is an irreversible and brain-penetrant small molecule inhibitor targeting both wildtype HER2 and oncogenic HER2 mutants, including the recalcitrant exon 20 mutations. IAM1363, discovered through Iambic Therapeutics' AI-driven discovery platform, represents the only example of a Type II HER2 inhibitor. It was designed to avoid off-target toxicities from EGFR inhibition thus expanding the therapeutic index over existing HER2 inhibitors. In preclinical studies, IAM1363 shows preferential tumor enrichment, a unique feature observed across tumor types and anatomic sites. The promising target specificity and pharmacokinetic profile of IAM1363 offers the potential to bridge gaps left by current standard of care HER2 targeted treatments. Methods: IAM1363-01 is a first-in-human, multicenter, open-label, Phase 1/1b dose escalation and expansion trial evaluating IAM1363 as monotherapy and in combination with trastuzumab. The study will enroll patients with relapsed/refractory malignancies that have documented HER2 gene alterations (amplification or tyrosine kinase domain mutations) or protein overexpression. Prior treatment with HER2 directed therapies is allowed after a washout period. Part 1, dose escalation, will enroll patients with any tumor type. Part 2 will optimize IAM1363 dosing as monotherapy and in combination with trastuzumab. Part 3 consists of a Simon 2-Stage evaluation of IAM1363 as monotherapy in patients with colorectal, non-small cell lung, and bladder cancer with or without brain metastases and in combination with trastuzumab in breast cancer patients with brain metastases. Key objectives are to establish the safety and tolerability of IAM1363, characterize PK/PD, and determine the recommended Phase 2 dose. Exploratory analysis will correlate HER2 expression level/mutation status with tumor response and tolerability. IAM1363 will be given orally once daily at a starting dose of 120 mg/day in up to 4 planned dose levels. Dose escalation employs an accelerated titration design that transitions to a standard 3 + 3 design based on protocol-specific criteria. Up to 287 patients will be enrolled at approximately 20 sites and treated until disease progression or unacceptable toxicity. The trial is designed to establish the safety profile of IAM1363 as a single agent and in combination with trastuzumab and to provide initial proof of antitumor activity in malignancies with HER2 overexpression, gene amplification, or tyrosine kinase mutations, including in patients with brain metastases. Clinical trial information: NCT06253871 .

Coping with inter-observer variability when assessing AI for scoring of HER2-stained whole slides.

e12571 Background: Around 15% of breast carcinomas exhibit Human Epidermal growth factor receptor 2 (HER2) overexpression due to gene amplification. HER2 protein levels are assessed by Immunohistochemistry (IHC) with 4 scores (0, 1+, 2+, 3+). Only score 3+ (IHC) cases and score 2+ (IHC) with proven HER2 gene amplification are eligible for targeted anti-HER2 therapies; others are HER2-negative. However, tumors with score 1+ and 2+ not amplified could benefit from treatment with the new HER2-based antibody-drug conjugates, requiring an accurate HER2 scoring, which is challenged by interobserver variability. This drawback is challenging for AI-based HER2 scoring assessment, and it is thus important to understand this inter-variability and then be able to propose a probabilistic framework which quantifies and explains the discrepancy between the AI analysis and the pathologist scoring. Methods: We introduce a novel probabilistic framework designed to assign probabilities to scores generated by AI algorithms. To the best of our knowledge, this represents the pioneering effort to quantify the uncertainty surrounding AI predictive models for HER2 scores. The methodology relies on a high-dimensional multivariate Gaussian approximation of the HER2 scoring process, hinting on the precise identification of marked cells to a specified category based on membrane completeness and staining intensity. Introducing uncertainty in the categorical identification enables the quantification of uncertainty in the overall AI-scoring at the whole slide image (WSI) level. Consequently, instead of offering a singular score, we can allocate a probability of belonging to a particular category (0, 1+, 2+, or 3+) for the global score. This approach enables a comparison of the predicted likelihood with the distribution of scores among pathologists, rather than relying on a "hypothetical" ground truth, often determined by a majority-voting which can be noise-sensitive or which excludes ambiguous cases when an agreement is hard to reach. Results: For illustration, we use the Kwant HER2 algorithm developed by DiaDeep on a validation set of 68 HER2 cases, previously scored by three expert pathologists. The framework allows us to understand the discrepancy between pathologists as we introduce nuance to the AI scoring and underlines narrow probability margins in borderline cases, therefore depicting the inherent challenge for pathologists to draw a clear demarcation between closely aligned scores categories. Conclusions: The proposed framework underscores the intrinsic variability of HER2 scoring between pathologists and allows to analyze the AI predictions for HER2 scoring with more nuance, consequently enabling a more critical analysis of the results compared to a singular raw output. As we enter a new era of AI-assisted diagnosis, such a method could improve the way of assessing new AI tools and help interpret their results.

Assessing clinical pathological characteristics and gene expression patterns associated with hepatoid adenocarcinoma of the stomach.

The objective of this study is to assess the clinical pathological attributes of Hepatoid Adenocarcinoma of the Stomach (HAS) and to delineate the differential diagnostic considerations about it. The investigation involved analyzing 31 HAS cases using histomorphological assessment, immunohistochemical profiling, and relevant gene detection methodologies. Among the 31 HAS cases, 9 (29.0%) were of trabecular hepatoid adenocarcinoma of the stomach, 7 (22.6%) were of glandular hepatoid adenocarcinoma of the stomach, 4 (12.9%) were of nesting hepatoid adenocarcinoma of the stomach, 3 (9.7%) were of clear cell hepatoid adenocarcinoma of the stomach, and 8 (25.8%) were of diverse hepatoid adenocarcinoma of the stomach. Of these 31 cases, 24 were male, accounting for 77.4% of the cases. Serum alpha-fetoprotein (AFP) levels were notably elevated, with radioimmunoassay results reaching 1240ng/ml; 28 out of 31 cases had AFP levels below 25µg/l, accounting for 90.3%. Related genes: HER2 protein indicated positive expression on the cell membrane in 35.5% (11/31) of the cases; HER2 gene amplification detected by the FISH technique was 12.9% (4/31). Tumoral stromal lymphocytes exhibited a PD-1 positive expression rate of 58.1% (18/31). In gastric cancer tissues, the PD-L1 positive rate was 45.1% (14/31). HAS represents a distinctive subtype of gastric cancer with a propensity for mimicking other forms of tumors, underscoring the significance of discerning its unique histopathological attributes for accurate differential diagnosis and tailored therapeutic interventions.

Performance of HER2 DAKO HercepTest and Ventana 4B5 immunohistochemical assays on detecting HER2 gene-amplification in uterine serous carcinomas

We compared the performance of two commonly-used HER2 immunohistochemistry (IHC) assays in uterine serous carcinomas (USC), correlating with HER2 gene amplification by fluorescence in-situ hybridization (FISH). Sixty-five USCs were stained by both HercepTest™ and PATHWAY 4B5 assays. FISH was performed by HER2 IQFISH pharmDx. Consensus HER2 IHC scoring was performed, and HER2 testing results were evaluated using USC-specific criteria. Complete concordance between HercepTest and 4B5 assays was achieved in 44/65 tumors (68%). The overall HER2 IHC/FISH concordance was 94% (45/48) by HercepTest and 91% (42/46) by 4B5. All HER2 IHC 3+ cases with HercepTest (n = 6) and 4B5 (n = 4) were gene-amplified, corresponding to specificities of 100%. For cases with IHC 2+, 41% (7/17) by HercepTest and 42% (8/19) by 4B5 had HER2 gene amplification. The sensitivity for HercepTest and 4B5 were 38% and 25%, respectively, at a cut-off of IHC 3+ (P = 0.50), and were 81% and 75%, respectively, at a cut-off of IHC 2+ (P > 0.99). Among HER2 IHC 0–1+ cases, 3/42 cases by HercepTest and 4/42 cases by 4B5 showed amplified FISH results, corresponding to overall false negative rates of 19% for HercepTest and 25% for 4B5. By using USC-specific IHC scoring criteria, both HercepTest and 4B5 assays showed high specificities (100%) for HER2 gene amplification in IHC 3+ cases, high IHC/FISH concordance, and comparable sensitivity for detecting HER2 gene amplification. The notable false negative rates using IHC 2+ as a cut-off for reflexing FISH analysis may warrant consideration for performing FISH in IHC 1+ cases until more data become available.

HER2 mutation as an emerging target in advanced breast cancer.

HER2 activating mutations have emerged as oncogenic drivers and therapeutic targets in a variety of human tumors. In breast cancer, these deregulations occur at low frequency, and are mostly detected in HER2-nonamplified, metastatic disease. Preclinical evidence has clarified the role of hotspot mutations in HER2 constitutive activation, defining them as an alternative mechanism to HER2 gene amplification. Furthermore, recent clinical studies have indicated the emergence of newly acquired HER2 deregulations in significant proportions of breast cancer patients who experience disease progression following both endocrine and HER2-targeted therapies. As the involvement of HER2 mutation in therapy resistance may profoundly impact patient outcomes on successive therapies, several clinical trials are currently investigating the efficacy of various HER2-targeted drugs in HER2-mutant breast cancer. In this review, we firstly summarize the structural organization of the HER2 oncogene and its historical impact on breast cancer prognosis and therapeutic advancement. Then, we provide an overview of the frequencies and functional relevance of clinically recurrent HER2 mutations in breast cancer with a special focus on their role in therapeutic resistance. Finally, we provide a collection of the clinical trials that are currently exploring novel therapeutic approaches for this patient subset and discuss the related perspectives and challenges.

EGFR, HER2, and MET gene amplification and protein expression profiles in biliary tract cancer and their prognostic significance.

There are limited conventional chemotherapy options for biliary tract cancers (BTCs), a heterogenous group of lethal, rare malignancies. The receptor tyrosine kinase (RTK) is closely associated with the progression of human malignancies through the regulation of cell cycle. Overexpression or amplification of RTKs has been investigated as a potential biomarker and therapeutic target in BTC; herein, we investigate the value of such interventions. Overexpression of RTK proteins was examined by immunohistochemistry in 193 BTC samples, of which 137 were gallbladder carcinoma, 29 were perihilar cholangiocarcinoma, and 27 were intrahepatic cholangiocarcinoma. Silver in situ hybridization of MET and HER2 was performed to assess gene amplification. In the entire cancer group, gallbladder, perihilar, and intrahepatic, MET amplification rates were 15.7%, 19.0%, 3.4%, and 14.8%, respectively, and of HER2 amplification rates were 22.4%, 27.2%, 17.2%, and 3.7%, respectively. MET and HER2 protein expressions were significantly correlated with their gene amplification status. RTKs were significantly associated with adverse clinicopathologic features such as advanced pT category and lymph node metastasis. Overall survival was significantly shorter in MET-amplified (P = .024) and EGFR-overexpressed cases (P = .045). Recurrence-free survival was significantly correlated with HER2-amplified (P = .038) and EGFR-overexpressed cases (P = .046) in all patient groups. Overall and recurrence-free survival were significantly shorter in patients who were double positive for HER2 and EGFR. Our data suggested that MET, HER2, and EGFR might be potential therapeutic targets and that their co-expression is a strong prognostic factor for BTCs.