HER2 Expression Research Articles

Efficacy and safety of recombinant humanized anti-HER2 antibody-MMAE conjugate (RC48) in neoadjuvant for HER2-positive breast cancer: A single-arm phase II study.

e12636 Background: Breast cancer patients who achieve pCR after neoadjuvant therapy have a relatively good prognosis. Whether antibody‐drug conjugates (ADCs) can replace traditional chemotherapy combined with dual-target therapy in neoadjuvant therapy still needs to be explored. RC48 is a novel recombinant human anti-HER2 monoclonal antibody conjugated with a microtubule inhibitor (MMAE) via a cleavable linker, which can effectively kill HER2-positive tumors as well as tumors with low or heterogeneous HER2 expression through the bystander effect. The purpose of this study was to evaluate the efficacy and safety of RC48 in neoadjuvant treatment of HER2-positive breast cancer. Methods: Patients with HER2-positive breast cancer (size>20mm) or confirmed axillary lymph node metastasis were eligible and received RC48 at a dose of 2.5mg/kg alone every 2 weeks for 6 cycles followed by surgery. EC was administered postoperatively every 21 days for 4 cycles. Trastuzumab combined with pertuzumab was administered for 1 year in the adjuvant setting. The primary endpoints were ORR and pCR rates. Results: 23 patients had been enrolled, and all of them had completed surgical treatment. The median age was 45(38-70) years. The current results showed that 13.0% (3/23) achieved pCR, 78.3% (18/23) achieved PR, and 8.7% (2/23) experienced PD. The ORR was 91.3%. 42% (5/12) of patients with initially positive axillary lymph nodes turned negative after surgery. 11.8% (2/17) HR-/HER2+ patients achieved pCR. According to the proportion of target lesion reduction, patients were divided into mild response (0-50%) and moderate-to-severe response (51%-100%). In the HR-/HER2+ subtype group, 23.5% (4/17) had a mild response, and 76.5% (13/17) had a moderate-to-severe response. 6 patients with HR+ have been enrolled, and 16.7% (1/6) of them achieved pCR. All of HR+ subtypes had a moderate-to-severe response. No relevant serious (grade 3/4) toxicity has been reported. Conclusions: The present data showed an acceptable pCR rate with RC48 in HER2-positive breast cancer. Although the pCR rate was lower than the traditional chemotherapy combined with targeted therapy, the effect of rapid reduction of tumor volume was better (the moderate-severe remission rate was 82.6%). For HR+/HER2+ breast cancer, the ORR in this study reached 100%, indicating that the novel ADC had a significant inhibitory effect on the crosstalk between ER and HER2. And it was expected that the Destiny Breast 11 study would show similar results. This scheme had a good negative conversion rate for patients with positive axillary lymph nodes. Finally, RC48 provided a neoadjuvant treatment option with low toxicity and high patient compliance for HER2-positive breast cancer. Clinical trial information: NCT05134519 .

Comprehensive analysis of TROP2, PD-L1, stromal (s)TILs, and HER2 expression patterns in patients (pts) with metastatic HR+HER2- breast cancer.

1062 Background: Immune checkpoint inhibitors (ICI) have shown limited efficacy in hormone receptor positive (HR+) metastatic breast cancer (mBC) and the optimal ICI-based combination is unknown. The TROP2 antibody-drug conjugate sacituzumab govitecan (SG) demonstrated antitumor activity with a 5.5-month median PFS in endocrine refractory HR+ mBC. Given SG's potential for anticancer immunity, we sought to evaluate expression patterns of biomarkers of interest in HR+ mBC. Methods: This retrospective study included pts with HR+HER2- mBC identified at DFCI between 10/2020 and 12/2021 who received 0-1 prior lines of chemotherapy in the metastatic setting and consented to analysis of archival FFPE tissue samples. We aimed to 1) characterize expression patterns of TROP2 (SP295 H-score), PD-L1 (22C3 CPS), sTILs and HER2 (per central pathology review) in the most recent available sample; 2) assess the prognostic value of selected biomarker combinations for overall survival (OS) defined as the time from consent to either death due to any cause or last follow-up (Cox proportional hazard models; p-value <0.05 considered significant). Results: Among 142 pts included, median age at diagnosis was 46 yrs (IQR: 40–56). Baseline characteristics are shown (Table). At least one biomarker was available for 123 subjects (86.6%). TROP2 expression (n=61) was Medium/High (M-H: 101-300) in 43 pts (70.5%) and Low (L: 0-100) in 18 (29.5%). PD-L1 central assessment (n=120) revealed CPS ≥1 (PD-L1+) in 32 pts (26.7%) and <1 (PD-L1-) in 88 (73.3%); only 7 (5.8%) pts had CPS ≥10. sTILs (n=87) were ≥10% in 14 pts (16.1%) and <10% in 73 (83.9%). When analyzing TROP2 and PD-L1 (n=61), 15 pts (24.6%) were TROP2-M-H/PD-L1+, 28 (45.9%) were TROP2-M-H/PD-L1-, 5 (8.2%) were TROP2-L/PD-L1+, and 13 (21.3%) were TROP2-L/PD-L1-. When analyzing TROP2 and sTILs (n=54), 6 pts (11.1%) were TROP2-M-H/sTILs ≥10%, 32 (59.3%) were TROP2-M-H/sTILs <10%, 2 (3.7%) were TROP2-L/sTILs ≥10% and 14 (25.9%) were TROP2-L/sTILs <10%. For TROP2 and HER2 (n=46), 26 pts (56.5%) had TROP2-M-H/HER2-low tumors, 7 (15.2%) TROP2-M-H/HER2-0, 3 (6.5%) TROP2-L/HER2-low, and 10 (21.7%) TROP2-Low/HER2-0. Median OS (n=138) was 43.8 months; stratification for selected biomarker combinations will be presented although no statistical significance was found. Correlations with NGS data and HER2DX are ongoing and will be presented. Conclusions: Analyzing biomarkers of interest in pts with HR+ mBC unveiled diverse patterns, without associations with OS. Patient characteristics. [Table: see text]

The predictive role of Ki67 in pathological complete response (pCR) and invasive disease-free survival (IDFS) in HER2-positive breast cancer: A retrospective study of 246 cases.

e12610 Background: While Ki67 is a routine diagnostic measure for early hormone receptor positive breast cancer, it is not integrated into the standard procedure for patients with Human Epidermal Growth Factor Receptor 2 (HER2)-positive breast cancer patients, given the substantial risk linked to HER2 expression alone. Consequently, the predictive significance of Ki67 in achieving pathological complete response (pCR) or invasive disease-free survival (IDFS) in this subgroup remains uncertain. Methods: This retrospective, bi-centric analysis focused on HER2-positive early breast cancer patients undergoing neoadjuvant chemotherapy from 2015 to 2023. We assessed the correlation between Ki67 values and the achievement of pathological complete response (pCR, defined as ypT0/is, pN0). Multivariable logistic regression analyzed the independent association of various clinical parameters, including Ki67, with pCR. Ki67 values were categorized into risk groups (low <15%, intermediate 15.1-35%, high >35%) following the GepardTrio data [1]. Kaplan-Meier estimator calculated differences in overall and invasive disease-free survival. Results: The study included 246 HER2-positive early breast cancer patients with known Ki67 expression, followed for a median of 42 months. The median age was 52 years. Final nodal status was pN0 in 80.5%, pN1 in 15%, and pN2 in 3.3%. Hormone receptor positivity was observed in 66% of patients. 147 patients (60%) achieved pCR. Median Ki67 was 30. When categorized, 13% were low, 41.5% intermediate, and 45.5% high risk. No correlation between Ki67 and pCR was observed (p=0.25). HER2 IHC score 3+ significantly increased pCR compared to IHC 2+ (62.2% vs. 44.6%, p=0.023). Hormone receptor-positive tumors had a lower pCR rate (52.7% vs. 72.4%, p=0.0016. 5-year overall survival was 96.5% for pCR and 83.8% for non-pCR (p=0.008). 5-year invasive disease-free survival showed no difference between low Ki67 (89.5%), intermediate Ki67 (79.9%), and high Ki67 (80.9%) groups (p=0.77). Conclusions: In this study, Ki67 did not predict pCR in HER2-positive breast cancer, providing no additional clinical value. HER2 IHC score and hormone receptor status were predictive indicators for pCR. Ki67 expression appears to lack additional value in HER2-positive breast cancer, considering resource implications. 1. Denkert C et al: Ann Oncol. 2013 Nov;24(11):2786-93. doi: 10.1093/annonc/mdt350. Epub 2013 Aug 22. PMID: 23970015.

Comparison of an Affibody-based Molecular Probe and 18F-FDG for Detecting HER2-Positive Breast Cancer at PET/CT.

Background Human epidermal growth factor receptor 2 (HER2) affibody-based tracers could be an alternative to nonspecific radiotracers for noninvasive detection of HER2 expression in breast cancer lesions at PET/CT. Purpose To compare an affibody-based tracer, Al18F-NOTA-HER2-BCH, and fluorine 18 (18F) fluorodeoxyglucose (FDG) for detecting HER2-positive breast cancer lesions on PET/CT images. Materials and Methods In this prospective study conducted from June 2020 to July 2023, participants with HER2-positive breast cancer underwent both Al18F-NOTA-HER2-BCH and 18F-FDG PET/CT. HER2 positivity was confirmed with pathologic assessment (immunohistochemistry test results of 3+, or 2+ followed by fluorescence in situ hybridization, indicated HER2 amplification). Two independent readers visually assessed the uptake of tracers on images. Lesion uptake was quantified using the maximum standardized uptake value (SUVmax) and target to background ratio (TBR) and compared using a general linear mixed model. Results A total of 42 participants (mean age, 56.3 years ± 10.1 [SD]; 41 female) with HER2-positive breast cancer were included; 42 (100%) had tumors that were detected with Al18F-NOTA-HER2-BCH PET/CT and 40 (95.2%) had tumors detected with 18F-FDG PET/CT. Primary tumors in two of 21 participants, lymph node metastases in four of 21 participants, bone metastases in four of 15 participants, and liver metastases in three of nine participants were visualized only with Al18F-NOTA-HER2-BCH. Lung metastasis in one of nine participants was visualized only with 18F-FDG. Al18F-NOTA-HER2-BCH enabled depiction of more suspected HER2-positive primary tumors (26 vs 21) and lymph node (170 vs 130), bone (92 vs 66), and liver (55 vs 27) metastases than 18F-FDG. The SUVmax and TBR values of primary tumors and lymph node, bone, and liver metastases were all higher on Al18F-NOTA-HER2-BCH images than on 18F-FDG images (median SUVmax range, 10.4-13.5 vs 3.4-6.2; P value range, <.001 to .02; median TBR range, 2.7-17.6 vs 1.2-7.8; P value range, <.001 to .001). No evidence of differences in the SUVmax and TBR for chest wall or lung metastases was observed between Al18F-NOTA-HER2-BCH and 18F-FDG (P value range, .06 to .53). Conclusion PET/CT with the affibody-based tracer Al18F-NOTA-HER2-BCH enabled detection of more primary lesions and lymph node, bone, and liver metastases than PET/CT using 18F-FDG. ClinicalTrials.gov Identifier: NCT04547309 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Ulaner in this issue.

Clinicopathological characteristics and outcomes of patients with HER2-low breast cancer: 6-year ambispective cohort study from India.

e23260 Background: Patients with low HER2-positive breast cancers are treated like those who are entirely HER2-negative. The DESTINY-Breast trials have proven Trastuzumab deruxtecan's benefit in the low HER2 subset. In Literature, limited data is available regarding the characteristics and outcomes of patients with low HER2 positivity from India. This study is done to address this research gap. Methods: This was an ambispective cohort study where we analysed the patients with carcinoma breast who were treated at our institute in the last 6 years. Out of 1845 patients, 243 were identified to have low HER2 expression. Patients were classified as Low HER2 positive if they had HER2 1+ or 2+ by IHC and negative by FISH. The clinical and pathological characteristics, progression-free survival (PFS) and overall survival (OS) of HER2 low subset, Estrogen Receptor (ER) positive and negative HER2 low cohorts and Metastatic (MBC) HER2 low patients were analysed separately. Results: A total of 243 patients were analysed. Of which 157 had HER2 2+ and 86 had 1+ expression. 240 were females. 79.8% were ER+ and 20.2% were ER negative among the total patients. 76.7% and 81.5% were ER+ in HER2 1+ and 2+ cohorts respectively. 78.2% were non-metastatic and 21.8% had MBC. 34.6% were treated with Neoadjuvant chemotherapy (NACT) and 42.4% with adjuvant chemotherapy (CT). 4.5% of patients treated with NACT attained PCR. 53.1% had T2, 16.8% had T4 disease. Most of the patients had N0 (35.4%) and N1(37%) disease. The OS of all low HER2+ patients were 4.97 years 95%CI(4.72-5.22). The OS in HER1+ and 2+ cohorts were 4.08 years and 5.04 years respectively. The PFS in low HER2+ patients was 5.01 years 95%CI(4.74-5.27) and 4.29 years and 4.89 years in HER2 1+ and 2+ cohorts. In the ER+ and negative cohorts, 31.4% of ER+ were treated with NACT and 45.4% of ER+ patients were treated with adjuvant CT. Most of ER+ low HER2 patients were of T2 stage (53.6%, p = 0.037). 36.6% were N0 and 34% were N1. 14.4% of ER+ low HER2 were MBC and 16.3% ER negative low HER2 were MBC. The OS of ER+ lowHER2+ cohort was 4.44 years and ER- HER2+ cohort was 4.43 years. Patients with MBC had a larger tumour size and nodal positivity (T4 43.4%, N1 37.8%,p = 0.001). The PFS and OS in MBC were 3.42 and 3.07 years compared to 5.29 years and 5.37 years in non-metastatic patients. Patients who were treated with NACT had an OS and PFS of 4.24 and 4.20 years and those who were treated with adjuvant CT had an OS of 5.39 years. Conclusions: The data on low HER2-positive patients is scarce in the Indian population. The low HER2+ patients had a PFS of 4.97 years and an OS of 5.01 years. Most of the patients had a T2 and N1 disease. The research gap low HER2+ subset is significant, especially considering the recent approval of trastuzumab deruxtican in India. With ongoing trials in MBC and non-metastatic settings, the benefit from this newer option may become clearer, particularly in ER+ low HER2 subset.

Association of mammographic and sonographic findings with prognostic molecular factors and hormone receptor expression in malignant breast lesions.

The aim of this study was to determine whether mammographic and sonographic features of malignant breast lesions are correlated with tumor histologic grade, hormonal receptor, human epidermal growth factor receptor 2 (HER2), and Ki-67 status. In this retrospective study, imaging and histopathological findings of 187 biopsy-proven breast cancer cases from November 2019 to February 2021 were reviewed. The Chi-square test was used to examine the potential correlation between mammographic and sonographic characteristics with histopathological features such as hormonal receptor, HER2 status, Ki-67 labeling index, and histological grade. We observed that microlobulated margin as well as oval/round morphology in mammograms correlate with triple-negative intrinsic subtype (P = 0.006 and P = 0.004). The presence of calcification in sonography was significantly higher in the luminal-B subtype (P = 0.002). Furthermore, ill-defined margins in mammography were significantly higher in amplified HER2 expression (P = 0.004) in the same manner as an oval/round shape in higher levels of Ki-67 (P = 0.030). Mammography and sonography features may reflect the biological behavior of various subtypes of breast cancer and can detect more aggressive breast cancers that can mimic benign or less malignant appearing lesions. These findings may be an excellent predictor for some subtypes like triple-negative breast cancer. Studying the range of these imaging characteristics may help in better understanding the prognosis, choosing a treatment strategy, and predicting response to treatment.

Efficacy and safety of dalpiciclib, fulvestrant, and pyrotinib in HR+ HER2-low advanced breast cancer following cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors and aromatase inhibitors (AIs): A Bayesian optimal phase II trial.

e13056 Background: Cross-line treatment with CDK4/6 inhibitors is a challenging topic. Currently, the MAINTAIN study, which involves switching CDK4/6 inhibitors and endocrine therapy, is the only one with positive results. Additionally, in vitro studies have demonstrated that the combination of anti-HER2 agents with CDK4/6 inhibitors, along with fulvestrant, can synergistically enhance inhibition in cell lines with low HER2 expression. The present study aims to assess the efficacy and safety of dalpiciclib, fulvestrant, and pyrotinib in patients with HR-positive and HER2-low advanced breast cancer (BC), who have experienced disease progression after treatment with CDK4/6 inhibitors and AIs. Methods: We propose a single-arm Bayesian optimal phase II design with a time-to-event endpoint. Key eligibility criteria include patients over 18 years of age with HR+, HER2-low advanced BC, disease progression following treatment with CDK4/6 inhibitors and AIs, no more than one line of chemotherapy. Patients who meet these criteria will receive oral dalpiciclib at a dose of 125 mg/day (three weeks on and one week off), intramuscular fulvestrant at a dose of 500 mg every four weeks, and oral pyrotinib at a dose of 320 mg/day until intolerance or disease progression. The primary endpoint of the study is progression-free survival (PFS), and the secondary endpoints include objective response rate (ORR), disease control rate (DCR), overall survival, safety, and biomarker analysis. The study aims to enroll up to 30 patients, and an interim analysis will be conducted after the enrollment of 15 patients to make a go/no-go decision based on the stopping boundaries of the total observation time (TOT). Results: From May 2023 to November 2023, a total of 15 patients were enrolled in the study. The median age of the patients was 50 years (range: 36-72). Among these patients, 7 (46.7%) had visceral metastasis, 11 (73.3%) had undergone previous chemotherapy, 12 (80.0%) received abemaciclib, and 3 (20%) received palbociclib. The median duration of prior treatment with CDK4/6 inhibitors was 14 months (range: 5-33). As of January 24, 2024, a total of 9 patients underwent efficacy evaluation, revealing an ORR of 44.44% (4/9) and a DCR of 66.67% (6/9), 4 patients experienced disease progression. The TOT was 49.50 months, exceeding the predetermined stopping boundary of 22.54 months. Currently, the survival data are immature. The median follow-up period is 3.20 months (95% CI: 2.33-NA), and the median PFS has not been reached. Grade 3 and above treatment-related adverse events were reported in 40% (6/15) of the patients. Conclusions: The preliminary results indicate a certain level of efficacy and manageable safety. Based on these findings, the study will continue to enroll up to 30 participants. Clinical trial information: NCT05806671 .

Impact of HER2 low status on genomic signatures in triple negative breast cancer (TNBC).

1092 Background: HER2 status has become more important with new treatment regimens subcategorizing HER2 to into low (1+or 2+ FISH-) or absent HER2 expression. Through comprehensive genomic profiling (CGP), we aim to identify distinctive molecular features associated with various immunohistochemistry (IHC) categories of HER2 low tumors. Methods: Retrospective review of pathology specimens submitted to Foundation Medicine were done and 514 TNBC (ER-/PR-/HER20,1+,2+FISH-) and 191 3+/HER2 amplified clinically advanced BC underwent hybrid capture-based CGP to evaluate genomic alterations (GA) in 324 genes, MSI status and tumor mutational burden (TMB, mutations/Mb). PD-L1 expression was determined by IHC (Dako 22C3 TPS). Chi-square test and Mann Whitney U test were used in the statistical comparisons of the 2 groups. Statistical significance was defined as p &lt; 0.05. Results: 53.5% were HER2 IHC 0+, 31.5% were HER2 IHC 1+ and 15.0% were IHC 2+/FISH negative. The HER2 3+/amplified BC were 59% ER+ and 41% ER-. Notable differences in GA frequencies included a significant increase in PIK3CA GA in the HER2 2+ vs the HER 0+ and 1+ groups (p=.0003). A lower frequency in BRCA1 GA in the HER2 2+ (5.2%) vs the HER2 0+ (9.8%) was significant when compared to the 1.0% in the HER2 3+/amplified cases (p&lt;.0001). BRCA2 GA frequencies did not show statistically significant differences among the TNBC HER2 IHC score groups. TP53 and RB1 had the highest frequency in HER2 0+ samples, with decreasing prevalence in the HER2 1+, 2+ and 3+/amplified cases (p&lt;.0001 for both). There was also a trend towards higher frequency of CDH1 GA as the HER2 IHC score increased from 0 to 2+ among TNBC. There were no significant differences in immunotherapy biomarkers (MSI, TMB and PD-L1) based on HER2 status among the TNBC groups. TMB &gt;= 10 mutations/Mb was significantly higher in the HER2 3+/amplified group (p=.004). Conclusions: We found that TNBC HER2 2+ positive FISH show key molecular differences from their HER2 low (1+) or absent (0+) counterparts. The most substantial difference was an increase in GA in PIK3CA. While this is targetable in the hormone positive setting, its potential role as a target in the hormone negative setting is uncertain. Also noted but did not reach significance was a decrease in GA within BRCA1/2 and a positive linear relationship with CDH1 and HER2 IHC expression. These GA differences may indicate potential treatment options for different HER2 subgroups and warrant further investigation. Limitations of our study include the retrospective nature and the lack of clinical data. [Table: see text]

Landscape of HER2-low breast cancer: Insights from a six-year study on incidence and clinicopathological characteristics.

e13148 Background: Human epidermal growth factor receptor 2 (HER2)-low breast cancer has emerged as a subtype of breast cancer, defined by HER2 1+ or 2+ in immunohistochemistry (IHC) and the absence of the ERBB2 gene amplification on fluorescence in situ hybridization (FISH). Recent trials showed marked response of HER2 breast cancer to novel anti-HER2 antibody-drug conjugates, rising interest in the HER2-low subtype. To date, data on characteristics of HER2-low breast cancer subtype is limited. Herein, we describe the clinicopathological characteristics of HER2-low breast cancer subtype compared HER2-zero/negative breast cancer. Methods: Real-world data from the Anatomic Pathology Division of Hotel Dieu de France, spanning 2017-2022, was retrospectively collected. Patients with HER2-IHC 3+ and HER2-IHC 2+ with ISH-amplified (HER2-positive) were excluded to compare HER2-low to HER2-zero breast cancer subtypes. Patients were then categorized based on their hormone receptor (HR) status. Clinicopathological characteristics between the groups were compared using a Chi-Square and Mann–Whitney U tests. Results: Out of 1195 patients, we observed 341 (28.5%) HER2-low breast cancers cases. HER2-positive breast cancer cases (n=178; 14.9%) were subsequently excluded. There was no significant difference in age and sex between the HER2-low and the HER2-zero group (p=0.3 and 0.8, respectively). HER2-low breast cancer was associated with positive estrogen receptor (ER) status and positive progesterone receptor (PR) status (p&lt;0.001 and p=0.01, respectively). Ductal adenocarcinomas were more frequently observed in the HER2-low group, whereas lobular and metaplastic adenocarcinomas were especially prevalent in the HER2-zero group (all p&lt;0.001). When stratified by HR status, 87.4% of patients had HR-positive status and 12.6% were HR-negative. Furthermore, the occurrence rate of tumors with a low Ki-67 labeling index was comparable between the two groups (p=0.9). However, among the HR-negative group, HER2-low tumors tended to show lower proliferation index compared to HER2-zero tumors (p = 0.04; Table). Conclusions: In conclusion, this study showed that HER2-low is a distinct from HER2-zero and is frequently present among patients with breast cancer. Clinicopathological features such as histological type differ between HER2-zero and HER2-low breast cancer. Our findings suggest that, within HR-negative breast cancer, breast cancer with low HER2 expression exhibits a less aggressive profile when compared to HER2-zero tumors. [Table: see text]

Innovative fiber optic–based approach of HER2 expression quantitative assessment using inPROBE technology.

Innovative fiber optic–based approach of HER2 expression quantitative assessment using inPROBE technology.

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.

How overall survival is conditioned in the progression to treatment with cyclin inhibitors plus endocrine treatment in metastatic breast cancer with luminal phenotype.

e13079 Background: CDK4/6 inhibitors plus endocrinotherapy (ET) is the standard first-line treatment for metastatic breast cancer with a luminal phenotype. However, the response to this treatment is highly dependent on its previous efficacy. Methods: We analyzed the overall survival in a cohort of 127 patients with metastatic luminal breast cancer in progression after treatment with CDK4/6 inhibitors plus ET. Results: The median age of the group was 67 years (41-96), the interval time between initial diagnosis and first recurrence was 0 in 41 (32%), 1-60 months in 37 (29%) and more than 60 months in 39 (38%). The first line in the metastatic setting was CDK4/6 plus ET in 81 patients (64%), ET in 15 (12%) and 31 (24%) were treated with chemotherapy. The status of HER2 expression was HER2 low in 77% and 43 % had visceral metastases disease. The median progression-free survival for the patients treated with CDK4/6 inhibitors plus ET was 9 months, with a total of deaths of 69 (55%). Overall survival after progression on CDK4/6 plus ET was 38 months (28 – 47) and the most important factor for overall survival was the response time to treatment with CDK4/6 inhibitors plus ET. Conclusions: The most important factor for overall survival is the duration of treatment with CDK4/6 inhibitors plus ET. Patients with a response time of less than 6 months had a median overall survival after progression of 11 months (3 – 19), while the 6- to 12-month group had a median of 39 months (19 – 59) and the group with more than 12 months had the best prognosis with a median overall survival of 53 months (37 – 68). We need to improve the new treatment options for patients who respond for less than 6 months to treatment with CDK4/6 plus ET.

Prevalence of “HER2 ultra-low” among patients with advanced breast cancer with historical IHC0 status.

e13156 Background: Breast Cancer (BC) patients are classified as HER2-positive (IHC3+ or IHC2+/ISH+) or HER2-negative (IHC0, IHC1+ and 2+/ISH-). Within the HER2-negative category, patients who meet HER2-low (IHC1+ or IHC2+/ISH-) criteria can benefit from HER2 targeted therapy like trastuzumab deruxtecan. Patients who meet IHC0 criteria with incomplete and faint membrane staining in &gt;0 but ≤10% of tumor cells — defined as “HER2 Ultra-low”, may also benefit from HER2 targeted therapy. This study aimed to assess the prevalence of “HER2 Ultra-Low” expression based on re-scored HER2 IHC biopsy slides. Methods: This study utilized EHR data from all three US Mayo Clinic campuses. A total of 300 patients with advanced BC (stages III-IV), and clinically documented HER2 IHC0 status between Jan 2017 and Jan 2023, were identified. One biopsy slide per patient (IHC assay: VENTANA Pathway anti-HER2/neu (4B5) rabbit monoclonal primary antibody) was digitized and scanned at 40x magnification. Two Mayo Clinic pathologists independently scored and reported HER2 status according to 2023 ASCO-CAP guidelines and included tumor stain percentage for each slide. Patients were considered “HER2 Ultra-Low” if their slide was scored as IHC0 with &gt;0% but ≤10% staining. Cohen’s κ was used to quantify agreement between pathologists. Results: The re-scored patients (n=300) had a mean age of 57.8 years (SD=13.5), with ~97% having IHC0 documentation within 30 days of the reviewed biopsy slide. A total of 285 (95%) patients remained classified as IHC0 by at least one pathologist. Of these, 60% (n=171) were determined as “HER2 Ultra-low” by at least one pathologist. The rate of “HER2 Ultra-Low” per pathologist ranged from 43% (n=121) to 45% (n=104). The overall inter-pathologist concordance was 57%; patients with no observable HER2 IHC staining accounted for majority of the concordant patients (Table). Conclusions: About 3 in 5 advanced BC patients originally classified as HER2 IHC0 met the “HER2 Ultra-Low” criteria by at least one pathologist, implying that significant number of additional patients may benefit from HER2 targeted therapy. The relatively low concordance between HER2 expert pathologists in identifying lower levels of HER2 expression suggests the need for increased precision enabled by digital tools, leveraging AI, training for community practice pathologists, and continuing to follow best practice recommendations in determining HER2 IHC status. [Table: see text]

Molecular characterization of breast cancer cell lines in correlation with clinical markers

Cell lines are indispensable for biomedical research, offering a consistent platform for investigating cellular processes and disease mechanisms. Despite their value, cell lines possess limitations such as genetic drift and phenotypic alterations over successive passages, potentially compromising their relevance. Monoclonal derivation may not represent in vivo heterogeneity, particularly in cancer. Therefore, characterizing them becomes imperative. We aimed to identify breast cancer subtype-specific cell lines by assessing ER, PR, and HER-2 expression via immunohistochemistry and their concordance with molecular expression. We selected cell lines with consistent phenotypes that mimic primary cells and confirmed concordance in ER, PR, and HER-2 expression at protein and mRNA levels. Evaluation of ER, PR, and HER-2 was conducted using Immunocytochemistry (ICC), Immunofluorescence (IF), and real-time PCR across commonly used breast cancer cell lines. Results revealed differential expression patterns, with MCF-7 and T-47D cells showing positive ER and PR staining but negative HER-2 staining, while SK-BR-3 and HCC1954 cells exhibited positive HER-2 staining and negative ER and PR staining. Conversely, MDA-MB-231 and MDA-MB-468 cells displayed negative staining for all three markers. Real-time PCR analysis highlighted variations in HER-2 expression among the cell lines. Our investigation underscores MCF-7, SK-BR-3, MDA-MB-231, and MDA-MB-468 cell lines as pertinent models for studying major molecular subtypes of breast cancer.

Reproductive characteristics, menopausal status, race and ethnicity, and risk of breast cancer subtypes defined by ER, PR and HER2 status: the Breast Cancer Etiology in Minorities study

BackgroundAssociations between reproductive factors and risk of breast cancer differ by subtype defined by joint estrogen receptor (ER), progesterone receptor (PR), and HER2 expression status. Racial and ethnic differences in the incidence of breast cancer subtypes suggest etiologic heterogeneity, yet data are limited because most studies have included non-Hispanic White women only.MethodsWe analyzed harmonized data for 2,794 breast cancer cases and 4,579 controls, of whom 90% self-identified as African American, Asian American or Hispanic. Questionnaire data were pooled from three population-based studies conducted in California and data on tumor characteristics were obtained from the California Cancer Registry. The study sample included 1,530 luminal A (ER-positive and/or PR-positive, HER2-negative), 442 luminal B (ER-positive and/or PR-positive, HER2-positive), 578 triple-negative (TN; ER-negative, PR-negative, HER2-negative), and 244 HER2-enriched (ER-negative, PR-negative, HER2-positive) cases. We used multivariable unconditional logistic regression models to estimate subtype-specific ORs and 95% confidence intervals associated with parity, breast-feeding, and other reproductive characteristics by menopausal status and race and ethnicity.ResultsSubtype-specific associations with reproductive factors revealed some notable differences by menopausal status and race and ethnicity. Specifically, higher parity without breast-feeding was associated with higher risk of luminal A and TN subtypes among premenopausal African American women. In contrast, among Asian American and Hispanic women, regardless of menopausal status, higher parity with a breast-feeding history was associated with lower risk of luminal A subtype. Among premenopausal women only, luminal A subtype was associated with older age at first full-term pregnancy (FTP), longer interval between menarche and first FTP, and shorter interval since last FTP, with similar OR estimates across the three racial and ethnic groups.ConclusionsSubtype-specific associations with reproductive factors overall and by menopausal status, and race and ethnicity, showed some differences, underscoring that understanding etiologic heterogeneity in racially and ethnically diverse study samples is essential. Breast-feeding is likely the only reproductive factor that is potentially modifiable. Targeted efforts to promote and facilitate breast-feeding could help mitigate the adverse effects of higher parity among premenopausal African American women.

Case Study: Heterogeneity of and CD44+/CD24- Cancer Stem Cell Subpopulation of Breast Cancer Patients in Bandung, Indonesia

Breast cancer (BC) cells characteristics have played a crucial role in clinical strategies decision-making and patient outcome prediction. Although there have been several studies examining this, there are still relatively few that analyze stem cell subpopulations or protein biomarkers. The conducted research sought to elucidate breast cancer subtype characteristics based on immunohistochemical analysis and cancer stem cell presence based on flow cytometry analysis in three breast cancer samples from Bandung, Indonesia. A flow cytometry analysis was conducted to determine how much CD44/CD24 was expressed as a marker of cancer stem cell in isolated BC cells using various cell references, such as cell lines of SKBR-3, MDA-MB-468, and Hs587T. Immunohistochemistry analysis was carried out to investigate the expression of p53, HER2, PGR, Ki67, and ER in sample tissue sections. According to histological analysis, 2 samples were solid mammary carcinoma, and 1 sample was mammary fibroadenoma. Immunohistochemistry and histological analysis showed that all BC tissues are classified as Luminal B. In addition, a large percentage of CD44+/CD24- subpopulation was found in isolated BC cells (&gt; 90 % in patients 1 and 3; &gt; 60 % in patient 2). All samples showed similarity to Hs587T cell line characteristic. This study has successfully characterized solid mammary tumors and mammary fibroadenoma with luminal B characteristics. All specimens contained a high proportion of cancer stem cells. HIGHLIGHTS The characteristics of breast cancer (BC) cells are essential factors in clinical strategy decision-making and patient outcome prediction Solid mammary tumor and mammary fibroadenoma were the cancer subtypes of isolated BC tissues from 3 different patients. The cancer subtypes found in 3 different patient’s isolated BC were solid mammary tumor and mammary fibroadenoma BC tissues from all 3 patients expressed different level of HER2, p53, Ki67, PGR and ER. Based on markers expressed, those BC tissues were classified as luminal B tumors Based on flow cytometry analysis, all BC tissues contained a high proportion of cancer stem cells indicated by the high proportion of CD44+/CD24- subpopulation GRAPHICAL ABSTRACT

Comparing the HER2 Status of the Primary Tumor to That of Disseminated Tumor Cells in Early Breast Cancer.

Breast cancer remains a leading cause of cancer mortality in women globally. Despite advancements in systemic therapy, the risk of distant recurrence persists even after such treatment and may be linked to disseminated tumor cells (DTCs). Variability in molecular characteristics between primary tumors (PTs) and distant metastases underscores the need to comprehensively understand metastatic pathways. This retrospective study investigated discrepancies between HER2 expression in PTs and DTCs and their implications for survival outcomes in 201 early breast cancer (EBC) patients. We found a significant association between HER2 expression in PTs and DTCs when classifying tumors as HER2-high/low/negative. Patients whose HER2 status was discordant between PTs and DTCs exhibited worse distant disease-free survival than those with concordant status. Multivariate analysis confirmed the HER2 status of DTCs as an independent prognostic factor for distant DFS. These findings emphasize the importance of assessing HER2 expression in DTCs and its potential implications for tailored therapy strategies in EBC. Furthermore, prospective trials are needed to validate these findings and explore targeted therapies based on the molecular characteristics of DTCs.

Expression of HER2 in urothelial carcinoma and its significance

Abstract Objectives We explored the expression levels and clinical significance of human epidermal growth factor receptor 2 (HER2) in urothelial carcinoma (UC) tissues. Materials and methods Patient data were reviewed, and 111 paraffin specimens of UC obtained from the Department of Urology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, from 2020 to 2021 were collected. Immunohistochemistry was used to detect HER2 protein expression in all UC tumor tissues. χ 2 and Fisher exact tests were used to analyze the relationship between HER2 protein expression and clinicopathological data (sex, age, histopathological diagnosis, invasiveness, histopathological grade, maximum tumor diameter, muscle invasion, regional lymph node metastasis, and clinical stage). Results In this study, 92 cases (82.88%) showed HER2 protein expression, and there was a statistically significant difference in the distribution of HER2 positivity (immunohistochemistry 2+ and 3+) according to the pathological grades of UC (p = .021). Human epidermal growth factor receptor 2 positivity was not associated with sex, age, histopathological diagnosis, invasiveness, maximum tumor diameter, muscle invasion, regional lymph node metastasis, or clinical stage (all p &lt; .05). Conclusions HER2 protein is highly expressed in UC, and its expression may be closely related to the high pathological grade of UC.

Breast cancer in northern Peru: molecular subtypes and HER2 low.

This study aimed to understand the immunohistochemical profile of breast cancer and to identify the HER2 low subgroup in the northern macro-region of Peru. A cross-sectional study was conducted in 1176 patients from the Regional Institute of Neoplastic Diseases Northern Peru, from January 2016 to December 2023. We analyzed the data (age, histological type, grade and complementary results), with frequencies and percentages. The profile corresponded to: luminal B (45.6%); luminal A (24.7%); triple negative (18.2%); and HER2 positive non luminal (11.5%). In addition, 215 patients presented HER2 low (25.1% of those previously considered negative). This study provides evidence that the subtyping of breast cancer has changed, being luminal B the most frequent. It is essential to involve health policies to acquire targeted therapies considering HER2 low patients. Motivation for the study. Molecular classification of breast cancer allows the use of targeted treatments. Information on this profile in the northern macroregion of Peru is unknown. In addition, new therapies have appeared for a subgroup of patients. Main findings. In this study, the most frequent molecular subtypes were: luminal B, luminal A, triple negative and non-luminal HER2. Also, 18.3% of patients had low HER2 expression. Implications. Health policies should be aligned with scientific advances, to guarantee targeted therapies and to update the information in health manuals or protocols.

HER2 quantitative continuous scoring for accurate patient selection in HER2 negative trastuzumab deruxtecan treated breast cancer

Many targeted cancer therapies rely on biomarkers assessed by scoring of immunohistochemically (IHC)-stained tissue, which is subjective, semiquantitative, and does not account for expression heterogeneity. We describe an image analysis-based method for quantitative continuous scoring (QCS) of digital whole-slide images acquired from baseline human epidermal growth factor receptor 2 (HER2) IHC-stained breast cancer tissue. Candidate signatures for patient stratification using QCS of HER2 expression on subcellular compartments were identified, addressing the spatial distribution of tumor cells and tumor-infiltrating lymphocytes. Using data from trastuzumab deruxtecan-treated patients with HER2-positive and HER2-negative breast cancer from a phase 1 study (NCT02564900; DS8201-A-J101; N = 151), QCS-based patient stratification showed longer progression-free survival (14.8 vs 8.6 months) with higher prevalence of patient selection (76.4 vs 56.9%) and a better cross-validated log-rank p value (0.026 vs 0.26) than manual scoring based on the American Society of Clinical Oncology / College of American Pathologists guidelines. QCS-based features enriched the HER2-negative subgroup by correctly predicting 20 of 26 responders.