TEST:

PATHWAY antiHer2/neu (4B5) Rabbit Monoclonal Primary Antibody

Fluorescence in situ hybridization was negative for HER2amplification in one case (International Federation of Gynecology and Obstetrics, grade 1) and positive in the other (International Federation of Gynecology and Obstetrics, grade 3). Our findings contribute to the growing evidence that HER2 is overexpressed in a small proportion of ovarian endometrioid carcinoma, and thus may serve as a potential therapeutic target in selected cases.

The study showed the possibility of using antibodies of clones GM030, HER2/neu 4B5, PBM-46A6, GM010 (PrimeBioMed) on the Ventana Bench Marck Ultra automatic immunostainer using the detection system UltraView Universal DAB Detection Kit.

"Roche...announced today the approval of the CE Mark for the VENTANA HER2 (4B5) Rabbit Monoclonal Primary Antibody RxDx to identify metastatic breast cancer patients with low HER2 expression for whom ENHERTU (trastuzumab deruxtecan) may be considered as a targeted treatment....The VENTANA HER2 (4B5) test now includes a scoring algorithm that helps pathologists to identify 'low expressors' of HER2, assigning a HER2 low status to this group of patients. With this lower cutoff, the test is able to identify patients who may benefit from ENHERTU as a treatment option....The CE Mark of the new HER2-low indication expands on the intended use for Roche's proven, on-market VENTANA HER2 (4B5) test, delivering timely, clear and confident results."

Notable effectiveness of trastuzumab deruxtecan (T-DXd) in patients with HER2-low advanced breast cancer (BC) has focused pathologists' attention...Significant inter-institutional differences in HER2 IHC protocols were observed, and it may have impact on HER2-low status. Thus, we recommend standardizing HER2 IHC conditions to ensure precise patient selection for targeted therapy.

Introduction: HER2 (ERBB2) is a target for various anti-cancer therapies, including large (Trastuzumab deruxtecan) or small molecules (Neratinib). An AI-powered pan-cancer image analysis of HER2 IHC of tumor cells in conjunction with genomic data reveals a positive correlation between ex20ins and S310x ERBB2 mutation and protein expression. This correlation is also seen at the RNA level, but the lesser levels relative to ERBB2 amplified cases suggests the effect may be mediated at the protein level.

cMET and TROP2 were frequently expressed in RET+ aNSCLC, EGFR and HER3 were present in a lower proportion, HER2 was rarely found. These markers were not associated with a prognostic or predictive impact on RETi outcomes. The activity of novel therapeutic agents should be evaluated in this setting.

Background: DESTINY-Breast04 (DB-04) showed that trastuzumab deruxtecan improves survival vs chemotherapy in patients with human epidermal growth factor receptor 2 (HER2)-low (immunohistochemistry [IHC] 1+ or IHC 2+ with in situ hybridization negative) metastatic breast cancer (BC)... The degree of concordance between the CTA and non-CTAs varied among assay types and laboratory locations. A low NPA for some non-CTAs suggests the need for further assay optimization for HER2 IHC 0 evaluation.

HER2 ultra-low expression is present in the tumour entities investigated. The clinical benefit of this information has to be proven. Indication of source: 1 Efficacy and safety of trastuzumab deruxtecan (T-DXd) in patients (pts) with HER2-expressing solid tumors: DESTINY-PanTumor02 (DP-02) interim results.

No abstracts available

CLDN18.2+ expression is associated with early stage GACs, but with metastatic disease in E/GEJACs. CLDN18.2+ expression is not affected by preoperative treatment or HER2 status. These findings expand our recognition of subsets of patients who may benefit from targeted CLDN18.2 therapy.

In this large study using optimized UC-specific assays, 56% of UC samples were HER2+ or HER2-low. HER2 gene amplification was present in a subset of samples across HER2 expression levels by IHC. Accurate analysis of HER2 expression in UC could enable a clinically meaningful impact on this disease through the development of HER2-targeted therapies.

Recently, the FDA approved mirvetuximab soravtansine for platinum-resistant ovarian carcinoma with FOLR1 overexpression, typically high-grade serous carcinoma... To our knowledge, this is the largest study to date of FOLR1 expression in USC. Nearly 1 in 5 USC patients are FOLR1+, independent of HER2 status. Further research testing the efficacy of FOLR1-targeted therapy in USC is needed, as approval could potentially double the proportion of patients with available targeted therapies.

In endometrial clear cell carcinoma, we observed 8.7% of tumors with HER2 gene amplification. The HER2 immunohistochemical staining appears to be consistent with the HER2 gene amplification. It needs further cases to be validated.

Background: Anti-HER2 antibody-drug conjugate trastuzumab-deruxtecan has shown efficacy in patients with HER2-low metastatic breast cancer (BC)... These results are the evidence for the need of newly developed algorithms that are capable of distinguishing HER2-low from HER2-negative accurately.

Now, based on the Destiny-04 trial results, it underpins eligibility for T-DXd in patients with metastatic breast cancer... The small but consistent improvement across all performance metrics suggests greater accuracy, reliability and consistency of HER2 assessments in set 2. Experience with our explicit HER2 Low-focused scoring conventions has enhanced the concordance of pathologists' HER2 IHC scores, validating our approach. We will use these reference sets for peer training and developing our national external quality assurance program for HER2 Low breast cancers.

CRCs that were HER2/Het+ were invariably ISH positive, while NGS was not as sensitive for HER2 amplification in this subgroup. Our results suggest that ISH is likely unnecessary for CRC with 3+ HER2 overexpression in 10-49% of tumor cells, and that NGS has suboptimal sensitivity for this cohort.

DFF has an adverse effect on IHC evaluation of HER2 expression in invasive breast carcinoma. The results of this study reinforce the importance of adequate fixation. Especially for HER2-low cases, a small percentage reduction might change the final results and related treatment of the patient.

Our AI-based virtual biopsy approach provides evidence that taking only one Bx harbors a >25% risk to misclassify a HER2 1+ tumor as HER2 0, whereas three Bxs decrease this risk to around 10%. This study may thus impact the clinical practice of Bx regimens for breast cancer.

In the real world, even using the same pathway 4B5 assay with Benchmark platform, different analytic parameters are likely to have an impact on final HER2 results, especially in HER2-low cases. Pathologists and clinicians should be aware of these challenging analytical-related issues.

HER2 cytoplasmic granular staining was present in 29.7% of pure ACs using PATHWAY 4B5 platform. The rate of HER2 cytoplasmic granular staining on HercepTest platform was significantly lower than that of PATHWAY 4B5 and was only appeared in 2+ and 3+ cases, suggesting that the HercepTest platform is more suitable for the HER2 low expression cases. The IHC interpretation of HER2 3+ were highly consistent with FISH status.

There is a considerable overlap between mRNA values when correlated with HER2 IHC values regardless of the IHC scoring system used. Only a small percentage of cases fell in H-score category different from ASCO-CAP category, contributing to minimal difference seen in terms of correlation with mRNA scores suggesting that H-score has no advantage over ASCO-CAP scoring system.

AI demonstrates high accuracy in identifying HER2 expressions in breast cancer, with varying performance depending on the specific HER2 grade. Given the low risk of bias in most studies and the evident heterogeneity, further investigations are warranted to refine AI algorithms and expand their applications in this crucial diagnostic domain.

There was a high level of consensus among the four assays. The changes in HER2 scores among different assays can also cause the changes in heterogeneity patterns.

Based on this initial study, the combination of cell lines together with AI was found to be a potential and promising tool to evaluate HER2 IHC staining reproducibility. More studies with enriched numbers of BCs at the critical thresholds performed with the most common real-life IHC protocol settings including different IHC assays must be conducted to evaluate the robustness of this quality tool.

Results were correlated with exposure to trastuzumab therapy, the histologic tumor type, and other demographic variables... Non-membranous overexpression of HER2 staining in GEA is rare and is secondary to the abundance of p95 HER2 isoform in the setting of polysomy rather than ERBB2 amplification. Given the lack of associated amplification, this unusual staining pattern is unlikely to be clinically relevant.

Background: The DESTINY-Breast04(DB-04) trial has shown efficacy of breast cancer (BC) patients with HER2-low in the metastatic setting to Anti-HER2 antibody-drug conjugate trastuzumab-deruxtecan... We conclude that a significant number of patients will receive incorrect Anti-HER2-low therapy by simply taking the reported score on a historic sample. We recommend repeating the assay following the FDA-approved protocol on a large sample size such as excisional biopsy.

The uPath (4B5) IA tool is non inferior to manual HER2 IHC interpretation. A significant reduction in equivocal cases helps dive deeper into HER2 IHC spectrum (HER2 low and ultra-low). Thus QIA proves to be a viable alternative to manual interpretation.

Background: The DESTINY-Breast04(DB-04) trial has shown efficacy of breast cancer (BC) patients with HER2-low in the metastatic setting to Anti-HER2 antibody-drug conjugate trastuzumab-deruxtecan... We conclude that a significant number of patients will receive incorrect Anti-HER2-low therapy by simply taking the reported score on a historic sample. We recommend repeating the assay following the FDA-approved protocol on a large sample size such as excisional biopsy.

Interrater agreement was excellent for the old and new HER2 4B5 protocols, even when separating 0 and 1+, now a potentially relevant distinction. However, more staining in tumor and BBT was seen in the new protocol, with up to 38% of score 0 being reclassified as 1+/2+. This increased staining could potentially lead to 2+ cases being misclassified as 3+, especially when limited tumor is present.

Significant proportion of previous "HER2 negative" primaries and DM cases are reclassified as HER2 low. Discordant HER2 status between IBC primary and metastasis and between different DM sites demonstrated tumor heterogeneity and highlights the need for HER2 retesting in distant metastasis.

The findings through Kappa Cohen showed a lower discrepancy when classifying cases 3+ and 2+ (-0.52 and -0.35), compared to cases classified as 1+ (-0.043), which requires greater supervision and reevaluation of the algorithms and comparison of the same to reduce variability. Quantitative analysis through AI is a useful tool for diagnosis and standardization where the doubt is very specific. We also propose that for the future classification of her2 through AI, we consider simplifying it into negative, low expressor, and high expressor.

Claudin 18.2 positive colorectal adenocarcinomas (26/576, 5%) are frequently MMR deficient (19/26, 73%) and demonstrate distinct histologic features. Future studies addressing efficacy of zolbetuximab therapy in this subset of colorectal cancers are needed.

No abstract available

Our study demonstrated a high concordance between HER2 expression by IHC and ERBB2 gene expression by WTS in UC. Differences in ADC target expression between ERBB2-high vs. ERBB2-low UC may provide a rationale for combination treatment strategies with HER2-ADC. The association between high ERBB2 expression and survival advantage warrants further investigation.

In the ongoing RC48-CO14 phase 1b/2 study, DV + toripalimab demonstrated an objective response rate (ORR) of 83.3% in patients with HER2 IHC 2/3+ la/mUC and an ORR of 64.3% in those with IHC 1+ tumors...Patients in Arm B will receive platinum-containing chemotherapy with gemcitabine IV on Days 1 and 8 of every 3-week cycle, and either cisplatin or carboplatin on Day 1 of every 3-week cycle. Maintenance therapy with avelumab may be used where approved and available after completion of 4-6 cycles of 1L platinum-based chemotherapy, if clinically appropriate...Enrollment is currently ongoing in the United States and planned globally. Clinical trial information: NCT05911295.

Among these real-world patients, both HER2 and PDL1 positivity was lower than reported in other regions. Higher incidence of distal tumors, signet ring cells and diffuse histology could explain this difference. Correlation of PDL1 positivity between 22C3 and 28.8 was unknown in our population.

P1; Phase classification: P1b --> P1

Introduction: The Destiny Breast-04 Trial (DB-04) demonstrated the survival benefits of Trastuzumab Deruxtecan (T-DXd) for women with metastatic HER2 Low breast cancer, characterised by 1+ or 2+ IHC staining without amplification... This study revealed that when breast pathologists were provided explicit instructions on scoring pitfalls and HER2 Low-focused scoring conventions, their HER2 scores were concordant with expert consensus scores in 71.7% to 91.7% of cases. Discordant cases primarily involved cases with less than 20% of tumor cells expressing HER2. Utilising such an approach, peer training and quality assurance procedures will improve the accuracy and consistency of HER2 IHC assessment for better patient care.

In this large single institutional analysis of dual HER-2 testing, only 12% of cases demonstrate HER-2 amplification, and overall in our institutional pathology database, from 2001 – March 2023, 11.2% of cases are HER-2+ by either IHC or ISH. In our dual tested cohort, only 13.6% of IHC 2+ cases demonstrate amplification, and 13.8% are non-amplified, but have excess HER-2 copy number. We demonstrate a numerical increase in the rate of amplification, and copy number in non-amplified cases, associated with IHC score.

Although there is no recommendation for a specific antibody assay, the companion diagnostic test for trastuzumab deruxtecan in the USA is Ventana PATHWAY anti-HER2 monoclonal antibody (4B5) run on Benchmark Ultra instrument... Different from another Brazilian cohort where the prevalence of HER2-low was 50% with monoclonal anti-HER2 antibodies (Reinert et al., SABCS 2020), our data suggests that the reduced proportion of samples with HER2-low status may be related to antibody clone sensitivity and not linked to preanalytical factors or local ancestry/ cancer biology. Indeed, a recent Italian cohort also had lower than expected prevalence of HER2-low in surgical specimens using anti-HER2 Dako A0485 assay on Omnis instrument (Rossi et al., Breast Cancer Res Treat 2023). Prior studies have found differential analytical sensitivity of antibodies for HER2-low status, while HER2 score 3+ detection is equivalent (Ruschoff et al., Virchows Archiv 2022).

HER2-low prevalence in Chinese breast cancer patients was found to be consistent with global data, while additional 10.6% of patients were identified as HER2 IHC >0 to 0 to < 1+, in the Chinese breast cancer population based on rescored results. The concordance of HER2-low between the historical and rescored results was 91.6%, indicating that most cases could be reproducibly classified.

HER2 status was determined by IHC/FISH and NGS in 45 cases: 19 serous, 18 high-grade (unspecified histologic type, HGU), 5 endometrioid 1 carcinosarcoma, 1 undifferentiated and 1 gastric- type. IHC-FISH HER2 was positive in 11/45 (24.4%) of cases, all serous or HGU. NGS identified 3 cases as amplified (concordant) and 1 non-pathogenic SNV.