Advancing HER2-low breast cancer management: enhancing diagnosis and treatment strategies.

BACKGROUND: Recent evidence brought by novel anti-human epidermal growth factor receptor 2 (HER2) antibody-drug conjugates is leading to significant changes in HER2-negative breast cancer (BC) best practices. A new targetable category termed 'HER2-low' has been identified in tumors previously classified as 'HER2-negative'. Daily practice in pathology and medical oncology is expected to align to current recommendations, but patient access to novel anticancer drugs across geographies might be impeded due to local challenges. MATERIALS AND METHODS: An expert meeting involving ten regional pathology and oncology opinion leaders experienced in BC management in four Central and Eastern Europe (CEE) countries (Bulgaria, Croatia, Serbia, Slovenia) was held. Herein we summarized the current situation of HER2-low metastatic BC (mBC), local challenges, and action plans to prevent delays in patient access to testing and treatment based on expert opinion. RESULTS: Gaps and differences at multiple levels were identified across the four countries. These included variability in the local HER2-low epidemiology data, certification of pathology laboratories and quality control, and reimbursement conditions of testing and anticancer drugs for HER2-negative mBC. While clinical decisions were aligned to international guidelines in use, optimal access to testing and innovative treatment was restricted due to significant delays in reimbursement or limitative reimbursement conditions. CONCLUSIONS: Preventing delays in HER2-low mBC patient access to diagnosis and novel treatments is crucial to optimize outcomes. Multidisciplinary joint efforts and pro-active discussions between clinicians and decision makers are needed to improve care of HER2-low mBC patients in CEE countries.

[Tumor infiltrating lymphocytes (TILs) in triple negative breast cancer]. / Infil'triruyushchie opukhol' limfotsity (TILs) pri trizhdy negativnom rake molochnoi zhelezy.

BACKGROUND: Tumor infiltrating lymphocytes (TILs) are a promising inexpensive prognostic and predictive biomarker in breast cancer. High levels of TILs are associated with improved survival and higher probability to achieve pathological complete response in triple-negative breast cancer (TNBC). OBJECTIVE: To assess the level of TILs in TNBC samples and analyze the association between the level of TILs and the main pathological parameters, to identify their impact on long-term results. MATERIAL AND METHODS: The study included information on 140 patients with I-III stage TNBC and estrogen receptors <10%. Tumor tissue samples at baseline biopsies were evaluated the histological type, HER2 expression, estrogen expression levels, Ki-67 and TILs. The pathological response was evaluated according to the ypTNM, Miller-Payne, and RCB classifications. RESULTS: The average level of TILs in biopsy specimens before NACT was 29.3±23.1%. Low levels of TILs (<10%) were defined in 21% of cases, intermediate levels (≥10% to ≤40%) in 55% of cases, and high levels (>40%) in 24% of cases. Using the two-tiered system, low TILs (≤40%) were defined in 76% and high TILs (>40%) in 24% of cases. The level of TILs was correlated with histological grade (R=0.187; p=0.027) and estrogen receptor expression level (R=0.211; p=0.012). There were no significant differences depending on the level of TILs and other pathological parameters. Three-year event-free survival (EFS) in patients with high TILs levels was 95% versus 65% in the low TILs group (p=0.037). CONCLUSION: Stromal TILs are an important prognostic biomarker in TNBC. Using a cutoff of 40%, high TILs are significantly associated with longer EFS.

Whole genome sequencing of HER2-positive metastatic extramammary Paget's disease: a case report.

BACKGROUND: Extramammary Paget's disease (EMPD) is a rare cancer that occurs within the epithelium of the skin, arising predominantly in areas with high apocrine gland concentration such as the vulva, scrotum, penis and perianal regions. Here, we aim to integrate clinicopathological data with genomic analysis of aggressive, rapidly-progressing de novo metastatic EMPD responding to HER2-directed treatment in combination with other agents, to attain a more comprehensive understanding of the disease landscape. METHODS: Immunohistochemical staining on the scrotal wall tumor and bone marrow metastasis demonstrated HER2 overexpression. Whole genome sequencing of the tumor and matched blood was performed. RESULTS: Notable copy number gains (log2FC > 0.9) on chromosomes 7 and 8 were detected (n = 81), with 92.6% of these unique genes specifically located on chromosome 8. Prominent cancer-associated genes include ZNF703, HOOK3, DDHD2, LSM1, NSD3, ADAM9, BRF2, KAT6A and FGFR1. Interestingly, ERBB2 gene did not exhibit high copy number gain (log2FC = 0.4) although 90% of tumor cells stained HER2-positive. Enrichment in pathways associated with transforming growth factor-beta (TGFß) (FDR = 0.0376, Enrichment Ratio = 8.12) and fibroblast growth factor receptor (FGFR1) signaling (FDR = 0.0082, Enrichment Ratio = 2.3) was detected. Amplicon structure analysis revealed that this was a simple-linear amplification event. CONCLUSION: Whole genome sequencing revealed the underlying copy number variation landscape in HER2-positive metastatic EMPD. The presence of alternative signalling pathways and genetic variants suggests potential interactions with HER2 signalling, which possibly contributed to the HER2 overexpression and observed response to HER2-directed therapy combined with other agents in a comprehensive treatment regimen.

Trastuzumab-functionalized bionic pyrotinib liposomes for targeted therapy of HER2-positive breast cancer.

In this study, we prepared a bionic nanosystem of trastuzumab-functionalized SK-BR-3 cell membrane hybrid liposome-coated pyrotinib (Ptb-M-Lip-Her) for the treatment of HER2-positive breast cancer. Transmission electron microscopy, dynamic light scattering, polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting were used to verify the successful preparation of Ptb-M-Lip-Her. In vitro drug release experiments proved that Ptb-M-Lip-Her had a sustained release effect. Cell uptake experiments and in vivo imaging experiments proved that Ptb-M-Lip-Her had good targeting ability to homologous tumor cells (SK-BR-3). The results of cell experiments such as MTT, flow cytometry, immunofluorescence staining and in vivo antitumor experiments showed that Ptb-M-Lip-Her could significantly promote apoptosis and inhibit the proliferation of SK-BR-3 cells. These results clearly indicated that Ptb-M-Lip-Her may be a promising biomimetic nanosystem for targeted therapy of HER2-positive breast cancer.

In situ HER2 RNA expression as a predictor of pathologic complete response of HER2-positive breast cancer patients receiving neoadjuvant chemotherapy and anti-HER2 targeted treatment.

BACKGROUND: Immunohistochemistry (IHC) and in situ hybridization (ISH) remain standard biomarkers for therapeutic decisions in human epidermal growth factor 2 (HER2)-positive breast cancers (BCs); however, they are insufficient to explain the heterogeneous anti-HER2 response. METHODS: We aimed to investigate the correlation of in situ HER2 RNA expression (isHRE), using RNAscope, with HER2 biomarkers and the impact of isHRE on the pathological complete response (pCR) rates of 278 patients with HER2 IHC/fluorescence ISH (FISH)-positive BC receiving neoadjuvant chemotherapy and anti-HER2 targeted treatment (NCTT). RESULTS: We validated HER2 RNAscope scoring as a semiquantitative method to determine isHRE and showed a positive correlation between RNAscope scores and pCR rates, with particularly different rates between patients with a score of 5 versus 1-4 BCs (66.7% vs. 15.9%, p < 0.0001). There were higher RNAscope scores and pCR rates in patients with HER2 IHC 3 + versus IHC 2+/FISH + BCs and HER2 RNAscope scores and pCR rates showed similar non-linear positive correlations with HER2 copy numbers and HER2/centromere 17 ratios. Moreover, in each HER2-positive IHC/FISH category, higher pCR rates were observed in patients with RNAscope scores of 5 versus 1-4 BC. Patients achieving pCR had BCs with notably higher HER2 RNAscope scores. Multivariate analysis identified HER2 RNAscope 5 as a strong pCR predictor [odds ratio = 10.865, p < 0.001]. The combined impact of multivariate analysis-defined pCR predictors demonstrated that a higher pCR rate was observed in patients with a score of 5 versus a score of 1-4 BCs regardless of the status of hormone receptor and mono-or dual anti-HER2 blockade. CONCUSIONS: Our results demonstrated that high isHRE (RNAscope score 5) is a strong pCR predictor in patients with HER2-positive BCs receiving NCTT, highlighting the complementary role of isHRE in stratifying HER2 status in tissue. Such stratification is relevant to anti-HER2 therapeutic efficacy, particularly using the cutoff of score 1-4 versus 5.

Pooled analysis of NeoCARH and NeoCART trials: patient-reported outcomes in patients with early-stage breast cancer receiving platinum-based or anthracycline-based neoadjuvant chemotherapy.

PURPOSE: Anthracycline-based or platinum-based neoadjuvant chemotherapy belongs to the standard treatment for early-stage breast cancer (EBC) that is either triple-negative or human epidermal growth factor receptor 2 positive (HER2 +). Currently, there is a paucity of data comparing their impact on health-related quality of life (HRQoL). METHODS: Triple-negative or HER2 + EBC from our two prospective randomized controlled trials, neoCARH and neoCART, were divided into two groups based on the neoadjuvant chemotherapy regimens they received: anthracycline-based or platinum-based group. HRQoL was the exploratory endpoint in these two trials, which was assessed using the European Organization for Research and Treatment of Cancer Quality of Life-Core30 and Breast23 questionnaires. The primary variable of interest was the C30 summary score (C30-SumSc). Assessments were carried out at baseline, after neoadjuvant chemotherapy, and 1 year and 2 years after diagnosis. RESULTS: The mean questionnaires' compliance rate was 95.0%. After neoadjuvant chemotherapy, 210 patients had evaluable HRQoL data, the mean least square change from baseline for the platinum-based group was - 15.997 (95% confidence interval (CI): - 17.877 to - 14.117), and it was - 20.156 (95% CI: - 22.053 to - 18.258) for the anthracycline-based group (difference: 4.159, 95% CI: 1.462 to 6.855, P = 0.003, minimal important difference = 3). For the majority of the domains of interest assessed by the C30 and BR23 questionnaires, the platinum-based group demonstrated superior outcomes in comparison to the anthracycline-based group. CONCLUSION: Patients receiving platinum-based or anthracycline-based regimens both experienced worsened HRQoL after neoadjuvant chemotherapy; however, the former provided relatively better HRQoL compared with the latter. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov: NCT03140553. Registered 4 May 2017 (neoCARH). NCT03154749. Registered 16 May 2017 (neoCART).

Combined SERS-Raman screening of HER2-overexpressing or silenced breast cancer cell lines.

BACKGROUND: Breast cancer (BC) is a heterogeneous neoplasm characterized by several subtypes. One of the most aggressive with high metastasis rates presents overexpression of the human epidermal growth factor receptor 2 (HER2). A quantitative evaluation of HER2 levels is essential for a correct diagnosis, selection of the most appropriate therapeutic strategy and monitoring the response to therapy. RESULTS: In this paper, we propose the synergistic use of SERS and Raman technologies for the identification of HER2 expressing cells and its accurate assessment. To this end, we selected SKBR3 and MDA-MB-468 breast cancer cell lines, which have the highest and lowest HER2 expression, respectively, and MCF10A, a non-tumorigenic cell line from normal breast epithelium for comparison. The combined approach provides a quantitative estimate of HER2 expression and visualization of its distribution on the membrane at single cell level, clearly identifying cancer cells. Moreover, it provides a more comprehensive picture of the investigated cells disclosing a metabolic signature represented by an elevated content of proteins and aromatic amino acids. We further support these data by silencing the HER2 gene in SKBR3 cells, using the RNA interference technology, generating stable clones further analysed with the same combined methodology. Significant changes in HER2 expression are detected at single cell level before and after HER2 silencing and the HER2 status correlates with variations of fatty acids and downstream signalling molecule contents in the context of the general metabolic rewiring occurring in cancer cells. Specifically, HER2 silencing does reduce the growth ability but not the lipid metabolism that, instead, increases, suggesting that higher fatty acids biosynthesis and metabolism can occur independently of the proliferating potential tied to HER2 overexpression. CONCLUSIONS: Our results clearly demonstrate the efficacy of the combined SERS and Raman approach to definitely pose a correct diagnosis, further supported by the data obtained by the HER2 gene silencing. Furthermore, they pave the way to a new approach to monitor the efficacy of pharmacologic treatments with the aim to tailor personalized therapies and optimize patients' outcome.

Bisphenol-A in Drinking Water Accelerates Mammary Cancerogenesis and Favors an Immunosuppressive Tumor Microenvironment in BALB-neuT Mice.

Bisphenol-A (BPA), a synthetic compound ubiquitously present in the environment, can act as an endocrine disruptor by binding to both canonical and non-canonical estrogen receptors (ERs). Exposure to BPA has been linked to various cancers, in particular, those arising in hormone-targeted tissues such as the breast. In this study, we evaluated the effect of BPA intake through drinking water on ErbB2/neu-driven cancerogenesis in BALB-neuT mice, transgenic for a mutated ErbB2/neu receptor gene, which reproducibly develop carcinomas in all mammary glands. In this model, BPA accelerated mammary cancerogenesis with an increase in the number of tumors per mouse and a concurrent decrease in tumor-free and overall survival. As assessed by immunohistochemistry, BALB-neuT tumors were ER-negative but expressed high levels of the alternative estrogen receptor GPR30, regardless of BPA exposure. On the other hand, BPA exposure resulted in a marked upregulation of progesterone receptors in preinvasive tumors and of Ki67, CD31, and phosphorylated Akt in invasive tumors. Moreover, based on several infiltration markers of immune cells, BPA favored an immunosuppressive tumor microenvironment. Finally, in vitro cell survival studies performed on a cell line established from a BALB-neuT breast carcinoma confirmed that BPA's impact on cancer progression can be particularly relevant after chronic, low-dose exposure.

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.

Comprehensive genomic profiling and therapeutic implications for Taiwanese patients with treatment-naïve breast cancer.

BACKGROUND: Breast cancer is a heterogeneous disease categorized based on molecular characteristics, including hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) expression levels. The emergence of profiling technology has revealed multiple driver genomic alterations within each breast cancer subtype, serving as biomarkers to predict treatment outcomes. This study aimed to explore the genomic landscape of breast cancer in the Taiwanese population through comprehensive genomic profiling (CGP) and identify diagnostic and predictive biomarkers. METHODS: Targeted next-generation sequencing-based CGP was performed on 116 archived Taiwanese breast cancer specimens, assessing genomic alterations (GAs), including single nucleotide variants, copy number variants, fusion genes, tumor mutation burden (TMB), and microsatellite instability (MSI) status. Predictive variants for FDA-approved therapies were evaluated within each subtype. RESULTS: In the cohort, frequent mutations included PIK3CA (39.7%), TP53 (36.2%), KMT2C (9.5%), GATA3 (8.6%), and SF3B1 (6.9%). All subtypes had low TMB, with no MSI-H tumors. Among HR + HER2- patients, 42% (27/65) harbored activating PIK3CA mutations, implying potential sensitivity to PI3K inhibitors and resistance to endocrine therapies. HR + HER2- patients exhibited intrinsic hormonal resistance via FGFR1 gene gain/amplification (15%), exclusive of PI3K/AKT pathway alterations. Aberrations in the PI3K/AKT/mTOR and FGFR pathways were implicated in chemoresistance, with a 52.9% involvement in triple-negative breast cancer. In HER2+ tumors, 50% harbored GAs potentially conferring resistance to anti-HER2 therapies, including PIK3CA mutations (32%), MAP3K1 (2.9%), NF1 (2.9%), and copy number gain/amplification of FGFR1 (18%), FGFR3 (2.9%), EGFR (2.9%), and AKT2 (2.9%). CONCLUSION: This study presents CGP findings for treatment-naïve Taiwanese breast cancer, emphasizing its value in routine breast cancer management, disease classification, and treatment selection.

Novel engineered HER2 specific recombinant protein nanocages for targeted drug delivery.

Protein nanocages resemble natural biomimetic carriers and can be engineered to act as targeted delivery systems, making them an attractive option for various drug delivery and biomedical applications. Our research investigated the genetic link of a specific anti-HER2 peptide (LTVSPWY) to the exposed N-terminal region of the maize (Zea mays) ferritin 1 (ZmFer1) protein nanocage, employing either a 7-amino acid (for LTVS-ZmFer1) or 16-amino acid (for LTVS-L-ZmFer1) linker. We utilized a heat treatment method to load the chemotherapeutic drug doxorubicin into the protein nanocage. The construct with the longer linker (LTVS-L) produced a greater amount of soluble protein nanocage and was selected for further experiments. The average size, polydispersity index, and zeta potential of the engineered protein nanocage were 19.01 nm, 0.168, and - 2.13 mV, respectively. The LTVS-L-ZmFer1 protein nanocage exhibited excellent thermal stability, withstanding temperatures up to 100 °C with only partial denaturation. Furthermore, we observed that cellular uptake of the LTVS-L-ZmFer1 protein nanocages in HER2-positive breast cancer cells was significantly higher compared to ZmFer1 after labeling with FITC (fluorescein isothiocyanate) (P-value = 0.0001). In addition, we observed a significant decrease in the viability of SKBR3 cells when treated with DOX-loaded LTVS-L-ZmFer1 protein nanocages compared to cells treated with DOX-loaded ZmFer1 protein nanocages. Therefore, this new treatment strategy may prove to be an effective way to reduce both the side effects and toxicity associated with conventional cancer treatments in patients with HER2-positive breast cancer.

Prolonged Response to Afatinib and Crizotinib in a Rare Case of EGFR-, HER2-, MET- and ROS1-Alterated Lung Adenocarcinoma.

We present the case of a 70-year-old never-smoking female patient with epidermal growth factor receptor (EGFR) p.L858R-mutated metastatic non-small cell lung cancer (NSCLC). After three months of first-line treatment with erlotinib, progression occurred and platinum/pemetrexed was initiated, followed by a response for more than two years. After the progression, the molecular testing of a vertebral metastasis revealed a ROS proto-oncogene 1 (ROS1) translocation and a human epidermal growth factor receptor 2 (HER2) p.S310F mutation, in addition to the known EGFR p.L858R mutation. Crizotinib then led to a durable response of 17 months. The molecular retesting of the tumour cells obtained from the recurrent pleural effusion revealed the absence of the ROS1 translocation, whereas the EGFR and HER2 mutations were still present. Afatinib was added to the crizotinib, and the combination treatment resulted in another durable response of more than two years. The patient died more than 7 years after the initial diagnosis of metastatic NSCLC. This case demonstrates that the repeated molecular testing of metastatic NSCLC may identify new druggable genomic alterations that can impact the patient management and improve the patient outcome.

Migratory Tumor Cells Cooperate with Cancer Associated Fibroblasts in Hormone Receptor-Positive and HER2-Negative Breast Cancer.

Hormone receptor-positive and HER2-negative breast cancer (HR+/HER2-BC) is the most common type with a favorable prognosis under endocrine therapy. However, it still demonstrates unpredictable progression and recurrences influenced by high tumoral diversity and microenvironmental status. To address these heterogeneous molecular characteristics of HR+/HER2-BC, we aimed to simultaneously characterize its transcriptomic landscape and genetic architecture at the same resolution. Using advanced single-cell RNA and DNA sequencing techniques together, we defined four distinct tumor subtypes. Notably, the migratory tumor subtype was closely linked to genomic alterations of EGFR, related to the tumor-promoting behavior of IL6-positive inflammatory tumor-associated fibroblast, and contributing to poor prognosis. Our study comprehensively utilizes integrated analysis to uncover the complex dynamics of this breast cancer subtype, highlighting the pivotal role of the migratory tumor subtype in influencing surrounding cells. This sheds light on potential therapeutic targets by offering enhanced insights for HR+/HER2-BC treatment.

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.

Disrupting EGFR-HER2 Transactivation by Pertuzumab in HER2-Positive Cancer: Quantitative Analysis Reveals EGFR Signal Input as Potential Predictor of Therapeutic Outcome.

Pertuzumab (Perjeta®), a humanized antibody binding to the dimerization arm of HER2 (Human epidermal growth factor receptor-2), has failed as a monotherapy agent in HER2 overexpressing malignancies. Since the molecular interaction of HER2 with ligand-bound EGFR (epidermal growth factor receptor) has been implied in mitogenic signaling and malignant proliferation, we hypothesized that this interaction, rather than HER2 expression and oligomerization alone, could be a potential molecular target and predictor of the efficacy of pertuzumab treatment. Therefore, we investigated static and dynamic interactions between HER2 and EGFR molecules upon EGF stimulus in the presence and absence of pertuzumab in HER2+ EGFR+ SK-BR-3 breast tumor cells using Förster resonance energy transfer (FRET) microscopy and fluorescence correlation and cross-correlation spectroscopy (FCS/FCCS). The consequential activation of signaling and changes in cell proliferation were measured by Western blotting and MTT assay. The autocorrelation functions of HER2 diffusion were best fitted by a three-component model corrected for triplet formation, and among these components the slowly diffusing membrane component revealed aggregation induced by EGFR ligand binding, as evidenced by photon-counting histograms and co-diffusing fractions. This aggregation has efficiently been prevented by pertuzumab treatment, which also inhibited the post-stimulus interaction of EGFR and HER2, as monitored by changes in FRET efficiency. Overall, the data demonstrated that pertuzumab, by hindering post-stimulus interaction between EGFR and HER2, inhibits EGFR-evoked HER2 aggregation and phosphorylation and leads to a dose-dependent decrease in cell proliferation, particularly when higher amounts of EGF are present. Consequently, we propose that EGFR expression on HER2-positive tumors could be taken into consideration as a potential biomarker when predicting the outcome of pertuzumab treatment.

iGenSig-Rx: an integral genomic signature based white-box tool for modeling cancer therapeutic responses using multi-omics data.

Multi-omics sequencing is poised to revolutionize clinical care in the coming decade. However, there is a lack of effective and interpretable genome-wide modeling methods for the rational selection of patients for personalized interventions. To address this, we present iGenSig-Rx, an integral genomic signature-based approach, as a transparent tool for modeling therapeutic response using clinical trial datasets. This method adeptly addresses challenges related to cross-dataset modeling by capitalizing on high-dimensional redundant genomic features, analogous to reinforcing building pillars with redundant steel rods. Moreover, it integrates adaptive penalization of feature redundancy on a per-sample basis to prevent score flattening and mitigate overfitting. We then developed a purpose-built R package to implement this method for modeling clinical trial datasets. When applied to genomic datasets for HER2 targeted therapies, iGenSig-Rx model demonstrates consistent and reliable predictive power across four independent clinical trials. More importantly, the iGenSig-Rx model offers the level of transparency much needed for clinical application, allowing for clear explanations as to how the predictions are produced, how the features contribute to the prediction, and what are the key underlying pathways. We anticipate that iGenSig-Rx, as an interpretable class of multi-omics modeling methods, will find broad applications in big-data based precision oncology. The R package is available: https://github.com/wangxlab/iGenSig-Rx .

Pathological and clinical outcomes following neoadjuvant dual HER2 therapy for early-stage breast cancer: An Australian institutional real-world experience.

AIM: There has been significant progress made in developing novel targeted therapies in the neoadjuvant setting for non-metastatic HER2-positive breast cancer, which may be used in combination with conventional chemotherapy to optimise pathological responses at surgery. However, these therapies, particularly the chemotherapeutic components, may portend significant and long-lasting toxicity. Hence, de-escalation of treatment intensity has been an area of interest and was evaluated in the phase II NeoSphere study. Herein, we report the real-world pathological and survival outcomes from neoadjuvant taxane and dual HER2 blockade recorded at our centre. METHODS: This was a retrospective cohort study of patients receiving neoadjuvant pertuzumab, trastuzumab and taxane chemotherapy for non-metastatic HER2-positive breast cancer at a single centre in Sydney, Australia. We collected data pertaining to baseline demographic characteristics, pathological response rates, post-surgical prescribing patterns and also undertook survival analyses for invasive disease-free survival (iDFS) as well as exploratory analyses for correlations between pre-specified clinicopathologic factors and pathological response at surgery. RESULTS: Our population was largely similar at baseline to the NeoSphere study. 71 patients were included in the final analysis. 61% achieved a pathological complete response (pCR). Three patients received conventional chemotherapy in the adjuvant setting. 92% of included patients were alive and disease-free at 3 years of follow-up. Only 3 events of recurrence or death were recorded at a median follow-up of 32 months. No significant difference in iDFS was noted between patients achieving pCR and those with residual disease at surgery. CONCLUSION: This study demonstrates that de-escalated adjuvant treatment for HER2-positive early breast cancer achieved favourable pathological and long-term outcomes comparable to large trials, some utilising more intensive chemotherapeutic components.

Real-world treatment patterns of adjuvant endocrine therapy and ovarian suppression in premenopausal HR+/HER2+ breast cancer.

BACKGROUND: The optimal adjuvant endocrine therapy (ET) in hormone receptor positive (HR+) and human epidermal growth factor receptor 2 positive (HER2+) premenopausal breast cancer (BC) remains unclear. Moreover, the benefit and clinical indications of ovarian suppression (OS) is poorly elucidated. We described real-world patterns surrounding choice of ET and clinicopathologic features which predicted treatment with OS in a contemporary cohort of premenopausal women with HR+/HER2+ BC. METHODS: This retrospective analysis included premenopausal patients with nonmetastatic HR+/HER2+ BC from the CancerLinQ Discovery database from January 2010 to May 2020. Women were less than 50 years and received chemotherapy, anti-HER2 therapy, and ET. They were categorized into 1 of 4 groups based on type of ET prescribed at initiation: aromatase inhibitor (AI) + OS, OS, tamoxifen + OS, or tamoxifen. Multivariable logistic regression assessed associations between clinicopathologic features and OS use. RESULTS: Out of 360,540 patients with BC, 937 were included. The majority (n = 818, 87%) were prescribed tamoxifen, whereas 4 (0.4%), 50 (5.3%), and 65 (6.9%) received OS, tamoxifen + OS and AI + OS, respectively. No clinicopathologic features predicted OS use apart from age; patients <35 years were more likely to receive OS compared with those ≥35 years (odds ratio 2.33, p < 0.001). CONCLUSIONS: This is the first real-world study evaluating ET treatment patterns in HR+/HER2+ premenopausal BC. OS use was uncommon and the majority received tamoxifen as the preferred ET regardless of most clinicopathologic risk factors. Additional research is needed to optimize ET decisions in young women with this distinct BC subtype.

Analysis of Breast Cancer Brain Metastases Reveals an Enrichment of Cyclin-Dependent Kinase 12 Structural Rearrangements in Human Epidermal Growth Factor Receptor 2-Positive Disease.

PURPOSE: Genomic alterations have been identified in patients with breast cancer brain metastases (BCBMs), but large structural rearrangements have not been extensively studied. MATERIALS AND METHODS: We analyzed the genomic profiles of 822 BCBMs and compared them with 11,988 local, breast-biopsied breast cancers (BCs) and 15,516 non-CNS metastases (Non-CNS M) derived from formalin-fixed paraffin-embedded material using targeted capture sequencing. RESULTS: Nine genes with structural rearrangements were more prevalent within BCBMs as compared with local BCs and Non-CNS M (adjusted-P < .05) and displayed a prevalence of >0.5%. The most common rearrangements within BCBMs involves cyclin-dependent kinase 12 (CDK12; 3.53%) as compared with the local BC (0.86%; adjusted-P = 7.1 × 10-8) and Non-CNS M specimens (0.68%; adjusted-P = 3.7 × 10-10). CDK12 rearrangements had a significantly higher frequency within human epidermal growth factor receptor 2 (HER2)-positive BCBMs (14.59%) compared with HER2-positive BCs (7.80%; P = 4.6 × 10-3) and HER2-positive Non-CNS M (7.87%; P = 4.8 × 10-3). CONCLUSION: The most common structural rearrangements involve CDK12 with the higher prevalence in HER2-positive BCBMs. These data support more detailed investigation of the role and importance of CDK12 rearrangements in BCBMs.