HER2 Signaling Research Articles

YAP regulates HER3 signaling-driven adaptive resistance to RET inhibitors in RET-aberrant cancer.

Rearranged during transfection (RET) aberrations represent a targetable oncogene in several tumor types, with RET inhibitors displaying marked efficacy. However, some patients with RET-aberrant cancer are insensitive to RET tyrosine kinase inhibitors (TKIs). Recently, drug-tolerant mechanisms have attracted attention as targets for initial therapies to overcome drug resistance. The underlying mechanisms of drug-tolerant cell emergence treated with RET-TKIs derived from RET-aberrant cancer cells remain unknown. This study investigated the role of YAP-mediated HER3 signaling in the underlying mechanisms of adaptive resistance to RET-TKIs in RET-aberrant cancer cells. Four RET-aberrant cancer cell lines were used to assess sensitivity to the RET-TKIs selpercatinib and pralsetinib and to elucidate molecular mechanisms underlying adaptive resistance using RNA sequencing, phospho-RTK antibody arrays, chromatin immunoprecipitation assay, and luciferase reporter assays. Clinical specimens from patients with RET-fusion-positive lung cancer were analyzed for pre-treatment YAP expression and correlated with treatment outcomes. In high YAP-expressing RET-aberrant cancer cells, YAP-mediated HER3 signaling activation maintained cell survival and induced the emergence of cells tolerant to the RET-TKIs selpercatinib and pralsetinib. The pan-ErBB inhibitor afatinib and YAP/TEAD inhibitors verteporfin and K-975 sensitized YAP-expressing RET-aberrant cancer cells to the RET-TKIs selpercatinib and pralsetinib. Pre-treatment YAP expression in clinical specimens obtained from patients with RET-fusion-positive lung cancer was associated with poor RET-TKI treatment outcomes. The YAP-HER3 axis is crucial for the survival and adaptive resistance of high YAP-expressing RET-aberrant cancer cells treated with RET-TKIs. Combining YAP/HER3 inhibition with RET-TKIs represents a highly potent strategy for initial treatment.

Computational approach for counting of SISH amplification signals for HER2 status assessment

The human epidermal growth factor receptor 2 (HER2) gene is a critical biomarker for determining amplification status and targeting clinical therapies in breast cancer treatment. This study introduces a computer-aided method that automatically measures and scores HER2 gene status from invasive tissue regions of breast cancer using whole slide images (WSI) through silver in situ hybridization (SISH) staining. Image processing and deep learning techniques are employed to isolate untruncated and non-overlapping single nuclei from cancer regions. The Stardist deep learning model is fine-tuned on our HER2-SISH data to identify nuclei regions, followed by post-processing based on identified HER2 and CEP17 signals. Conventional thresholding techniques are used to segment HER2 and CEP17 signals. HER2 amplification status is determined by calculating the HER2-to-CEP17 signal ratio, in accordance with ASCO/CAP 2018 standards. The proposed method significantly reduces the effort and time required for quantification. Experimental results demonstrate a 0.91% correlation coefficient between pathologists manual enumeration and the proposed automatic SISH quantification approach. A one-sided paired t-test confirmed that the differences between the outcomes of the proposed method and the reference standard are statistically insignificant, with p-values exceeding 0.05. This study illustrates how deep learning can effectively automate HER2 status determination, demonstrating improvements over current manual methods and offering a robust, reproducible alternative for clinical practice.

The Prospective role of lapatinib as an adjuvant therapy in prevalent cancers: Insights from in silico analysis targeting EGFR and HER2

IntroductionVarious pieces of evidence suggest an elevation in the levels of EGFR and HER2 in different cancers leading to the proliferation, invasion, and metastasis of cancer cells. In this study, we conducted a comprehensive investigation into the expression alterations of these two receptors in various cancers using in silico data. In addition, we investigated the therapeutic potential of lapatinib as an inhibitor of these receptors in various cancer types. MethodsRNAseq data for prevalent cancers were downloaded from The Cancer Genome Atlas (TCGA). After initial preprocessing, expression changes of HER2, EGFR, and candidate genes—identified based on their association with EGFR and HER2 signaling pathways—were examined. Human protein atlas data were utilized to assess the protein expression of HER2 and EGFR. GSE129254 was employed to identify molecular pathways and candidate genes associated with lapatinib. The protein-protein interaction network was used to identify lapatinib-influenced hub genes. Clinical data for common cancers were used to investigate the correlation between the expression of candidate genes and patients' mortality rates by Cox regression test. ResultsThe findings clearly indicated a significant increase in the expression levels of HER2 and EGFR in cancers such as kidney, lung, breast, bladder, pancreas, head and neck, stomach, and endometrial, both at the mRNA and protein levels (p-value <0.01). Additionally, more than 30 % of samples in some cancers showed a twofold increase in HER2 or EGFR expression. The analysis of GSE129254 data revealed that lapatinib reduces the expression of numerous genes associated with cell proliferation. METTL1, LYAR, LTV1, CCND1, NOP2, and DDX21 were identified as hub genes related to the effect of lapatinib. Our results demonstrated that many hub genes exhibited elevated expression in candidate cancers, and the upregulation of some of them was correlated with poor prognosis. ConclusionOur results indicate an upregulation in the expression levels of HER2 and EGFR in certain common cancers, suggesting that lapatinib, in addition to breast cancer, could be considered for the treatment of these cancers. Furthermore, we demonstrated that some genes with increased expression in prevalent cancers and associated with poor prognosis have the potential to be modulated by lapatinib.

Pyrotinib and trastuzumab combination treatment synergistically overcomes HER2 dependency in HER2-positive breast cancer: insights from the PHILA trial

The PHILA study suggests that pyrotinib, trastuzumab, and docetaxel significantly improved progression-free survival (PFS) compared with placebo, trastuzumab, and docetaxel in patients with untreated HER2-positive metastatic breast cancer. In this study, we aimed to investigate the synergistic mechanisms of pyrotinib plus trastuzumab and provide further insights for the PHILA trial. The invitro activity of combination treatments was assessed through cell biological and biochemical experiments. The invivo efficacy was evaluated in cell-derived xenografts, a TUBO tumour model, and one clinical case. Next-generation sequencing was performed on circulating tumour DNA (ctDNA) from patients in the PHILA trial. The combination of pyrotinib and trastuzumab more effectively inhibited cell growth than pyrotinib or trastuzumab alone in models of HER2-dependent breast cancer. It potentiated membrane HER2 ubiquitination and downregulation, which resulted in a comprehensive blockade of the HER2 signalling pathway. The pyrotinib-altered membrane HER2 levels had no significant effect on trastuzumab-mediated antibody-dependent cell-mediated cytotoxicity (ADCC). We further validated the synergistic mechanisms in TUBO tumours and one clinical case, rather than models of HCC1954cells harbouring the PIK3CA H1047R mutation. Similarly, in our centre cohort of the PHILA study, patients with genetic alterations in the HER2 signalling cascade had significantly shorter median PFS than individuals with the wild-type pathway. Our findings underscore the robust synergy between pyrotinib and trastuzumab in overcoming HER2 dependency and provide a rationale for pyrotinib, trastuzumab, and docetaxel as one of the optimal choices for patients with untreated HER2-positive metastatic breast cancer, who are dependent on the HER2 signalling cascade. This work was supported by the National Key Research and Development Program of China (2021YFF1201300), the National Natural Science Foundation of China (82172875), the CAMS Innovation Fund for Medical Sciences (CIFMS) (2022-I2M-2-001), and the Joint Innovative Fund of Beijing Natural Science Foundation and Changping District (L234004).

LRG1 promotes metastatic colorectal cancer growth through HER3 signaling

Background and aimsTherapy failure in patients with metastatic colorectal cancer (mCRC, ∼80% occur in the liver) remains an overarching challenge. Preclinical studies demonstrated that HER3 promotes CRC cell survival, but therapies blocking the neuregulin-induced canonical HER3 signaling have made little impact in the clinic. Recent studies suggest that the liver microenvironment promotes CRC growth by activating HER3 in a neuregulin-independent fashion, thus elucidation of these mechanisms may reveal new strategies for treating patients with mCRC. MethodsPatient-derived primary liver endothelial cells (ECs) were used to interrogate EC-CRC crosstalk. We conducted proteomic analysis to identify EC-secreted factor(s) that triggers non-canonical HER3 activation in CRC, and determined the subsequent effects on mCRC using diverse murine mCRC models. In vitro studies with genetic and pharmacological interventions were used to map the non-canonical HER3 pathway. ResultsWe demonstrated that EC-secreted leucine-rich alpha-2-glycoprotein 1 (LRG1) directly binds and activates HER3 and promotes CRC growth distinct from neuregulin, the canonical HER3 ligand. Blocking host-derived LRG1 by gene knockout or a neutralizing antibody impaired mCRC outgrowth in the liver and prolonged mouse survival. We identified protein synthesis activated by the PI3K-PDK1-RSK-eIF4B axis as the biologically relevant signaling cascade downstream of the LRG1-HER3 interaction, which was not blocked by conventional HER3-specific antibodies that failed in prior clinical trials. ConclusionsLRG1 is a novel HER3 ligand and mediates liver-mCRC crosstalk. The LRG1-HER3 signaling axis is distinct from canonical HER3 signaling and represents a new therapeutic opportunity to treat patients with mCRC, and potentially other types of liver metastases.

A Non-Canonical p75HER2 Signaling Pathway Underlying Trastuzumab Action and Resistance in Breast Cancer.

Overexpression of HER2 occurs in 25% of breast cancer. Targeting HER2 has proven to be an effective therapeutic strategy for HER2-positive breast cancer. While trastuzumab is the most commonly used HER2 targeting agent, which has significantly improved outcomes, the overall response rate is low. To develop novel therapies to boost trastuzumab efficacy, it is critical to identify the mechanisms underlying trastuzumab action and resistance. We recently showed that the inhibition of breast cancer cell growth by trastuzumab is not through the inhibition of HER2 canonical signaling. Here we report the identification of a novel non-canonical HER2 signaling pathway and its interference by trastuzumab. We showed that HER2 signaled through a non-canonical pathway, regulated intramembrane proteolysis (RIP). In this pathway, HER2 is first cleaved by metalloprotease ADAM10 to produce an extracellular domain (ECD) that is released and the p95HER2 that contains the transmembrane domain (TM) and intracellular domain (ICD). p95HER2, if further cleaved by an intramembrane protease, γ-secretase, produced a soluble ICD p75HER2 with nuclear localization signal (NLS). p75HER2 is phosphorylated and translocated to the nucleus. Nuclear p75HER2 promotes cell proliferation. Trastuzumab targets this non-canonical HER2 pathway via inhibition of the proteolytic cleavage of HER2 by both ADAM10 and γ-secretase. However, p75HER2 pathway also confers resistance to trastuzumab once aberrantly activated. Combination of trastuzumab with ADAM10 and γ-secretase inhibitors completely blocks p75HER2 production in both BT474 and SKBR3 cells. We concluded that HER2 signals through the RIP signaling pathway that promotes cell proliferation and is targeted by trastuzumab. The aberrant HER2 RIP signaling confers resistance to trastuzumab that could be overcome by the application of inhibitors to ADAM10 and γ-secretase.

A Comprehensive Review of HER2 in Cancer Biology and Therapeutics.

Human epidermal growth factor receptor 2 (HER2), a targetable transmembrane glycoprotein receptor of the epidermal growth factor receptor (EGFR) family, plays a crucial role in cell proliferation, survival, and differentiation. Aberrant HER2 signaling is implicated in various cancers, particularly in breast and gastric cancers, where HER2 overexpression or amplification correlates with aggressive tumor behavior and poor prognosis. HER2-activating mutations contribute to accelerated tumorigenesis and metastasis. This review provides an overview of HER2 biology, signaling pathways, mechanisms of dysregulation, and diagnostic approaches, as well as therapeutic strategies targeting HER2 in cancer. Understanding the intricate details of HER2 regulation is essential for developing effective targeted therapies and improving patient outcomes.

Breast Cancer Stem Cells and Tumor Heterogeneity: Characteristics and Therapeutic Strategies.

Breast cancer is one of the most frequently detected malignancies worldwide. It is responsible for more than 15% of all death cases caused by cancer in women. Breast cancer is a heterogeneous disease representing various histological types, molecular characteristics, and clinical profiles. However, all breast cancers are organized in a hierarchy of heterogeneous cell populations, with a small proportion of cancer stem cells (breast cancer stem cells (BCSCs)) playing a putative role in cancer progression, and they are responsible for therapeutic failure. In different molecular subtypes of breast cancer, they present different characteristics, with specific marker profiles, prognoses, and treatments. Recent efforts have focused on tackling the Wnt, Notch, Hedgehog, PI3K/Akt/mTOR, and HER2 signaling pathways. Developing diagnostics and therapeutic strategies enables more efficient elimination of the tumor mass together with the stem cell population. Thus, the knowledge about appropriate therapeutic methods targeting both "normal" breast cancer cells and breast cancer stem cell subpopulations is crucial for success in cancer elimination.

Quantitative Measurement of HER2 Expression in Non–Small Cell Lung Cancer With a High-Sensitivity Assay

Recently, low human epidermal growth factor receptor 2 (HER2) protein expression has been proposed as a predictive biomarker for response to the antibody-drug conjugate trastuzumab deruxtecan (T-DXd) in metastatic breast cancer. HER2 expression in non–small cell lung cancer (NSCLC) patients has never been carefully measured, and little is known about the frequency of cases with unamplified but detectable levels of the protein. Although some HER2-targeted therapies have been studied in NSCLC patients, they have been restricted to those with genomic ERBB2 gene alterations, which only represent relatively rare cases of NSCLC. Still, emerging investigations of T-DXd in NSCLC have shown promise in patients with unamplified HER2. Taken together, we hypothesize that there may be many cases of NSCLC with levels of HER2 protein expression comparable with levels seen in breast cancer that benefit from T-DXd.Here, we used a previously validated, analytic, quantitative immunofluorescence (QIF) assay that is more sensitive than legacy clinical HER2 immunohistochemistry assays. We measured HER2 protein levels in NSCLC cases to determine the proportion of cases with detectable HER2 expression. Using cell line calibration microarrays alongside our QIF method enabled us to convert HER2 signal into units of attomoles per mm2. We found that over 63% of the 741 analyzed NSCLC cases exhibited HER2 expression above the limit of detection, with more than 17% of them exceeding the lower limit of quantification. Although the threshold for response to T-DXd in breast cancer is still unknown, many cases of NSCLC have expression in a range comparable to breast cancer cases with immunohistochemistry scores of 1+ or 2+. Our assay could potentially select NSCLC cases with a detectable target (ie, HER2) that might benefit from HER2 antibody-drug conjugates, irrespective of ERBB2 genomic alterations.

Pharmacological properties and clinical development overview of pertuzumab (genetical recombination), trastuzumab (genetical recombination) and vorhyaluronidase alfa (genetical recombination) (PHESGO® combination for ‍subcutaneous injection MA, IN)

Pertuzumab and trastuzumab are anti-HER2 humanized monoclonal antibodies with different mechanisms of action. Their combination is expected to suppress intracellular HER2 signaling additively or synergistically. Their combination is widely recommended worldwide and has been established as a standard of care for HER2-positive breast cancer. However, improvement is required because of the prolonged time of intravenous infusion. Vorhyaluronidase alfa (rHuPH20) depolymerizes hyaluronan in the subcutaneous connective tissue. It's reported to increase the permeability and absorption levels of drugs. PHESGO® combination for subcutaneous injection MA/IN (PHESGO®) is a fixed-dose combination of pertuzumab, trastuzumab, and rHuPH20. A confirmatory phase III study (FeDeriCa) was conducted following a dose-finding phase I study (BO30185). Patients with HER2-positive early breast cancer were randomly assigned to receive either intravenous infusion of pertuzumab and trastuzumab or subcutaneous injection of PHESGO®, in combination with chemotherapy, to compare the pharmacokinetics (PK), efficacy and safety. A phase II study (PHranceSCa) was also conducted to assess patients' preference and satisfaction. Based on these results, population PK analysis, and other data, PHESGO® obtained marketing approval in Japan in September 2023 with indications for "HER2-positive breast cancer" and "advanced or recurrent HER2-positive colorectal cancer that has progressed following cancer chemotherapy and is not amenable to curative resection". By reducing the administration time, PHESGO® is expected to contribute to various needs of patients and improvement of their daily lives. Since drug preparation is not required, it can provide convenience to healthcare professionals, leading to stress reduction of medical resources as well.

A prospective study of HER3 expression pre and post neoadjuvant therapy of different breast cancer subtypes: implications for HER3 imaging therapy guidance

PurposeHER3, a member of the EGFR receptor family, plays a central role in driving oncogenic cell proliferation in breast cancer. Novel HER3 therapeutics are showing promising results while recently developed HER3 PET imaging modalities aid in predicting and assessing early treatment response. However, baseline HER3 expression, as well as changes in expression while on neoadjuvant therapy, have not been well-characterized. We conducted a prospective clinical study, pre- and post-neoadjuvant/systemic therapy, in patients with newly diagnosed breast cancer to determine HER3 expression, and to identify possible resistance mechanisms maintained through the HER3 receptor.Experimental designThe study was conducted between May 25, 2018 and October 12, 2019. Thirty-four patients with newly diagnosed breast cancer of any subtype (ER ± , PR ± , HER2 ±) were enrolled in the study. Two core biopsy specimens were obtained from each patient at the time of diagnosis. Four patients underwent a second research biopsy following initiation of neoadjuvant/systemic therapy or systemic therapy which we define as neoadjuvant therapy. Molecular characterization of HER3 and downstream signaling nodes of the PI3K/AKT and MAPK pathways pre- and post-initiation of therapy was performed. Transcriptional validation of finings was performed in an external dataset (GSE122630).ResultsVariable baseline HER3 expression was found in newly diagnosed breast cancer and correlated positively with pAKT across subtypes (r = 0.45). In patients receiving neoadjuvant/systemic therapy, changes in HER3 expression were variable. In a hormone receptor-positive (ER +/PR +/HER2-) patient, there was a statistically significant increase in HER3 expression post neoadjuvant therapy, while there was no significant change in HER3 expression in a ER +/PR +/HER2+ patient. However, both of these patients showed increased downstream signaling in the PI3K/AKT pathway. One subject with ER +/PR −/HER2− breast cancer and another subject with ER +/PR +/HER2 + breast cancer showed decreased HER3 expression. Transcriptomic findings, revealed an immune suppressive environment in patients with decreased HER3 expression post therapy.ConclusionThis study demonstrates variable HER3 expression across breast cancer subtypes. HER3 expression can be assessed early, post-neoadjuvant therapy, providing valuable insight into cancer biology and potentially serving as a prognostic biomarker. Clinical translation of neoadjuvant therapy assessment can be achieved using HER3 PET imaging, offering real-time information on tumor biology and guiding personalized treatment for breast cancer patients.

Discovery of Potent and Selective Covalent Inhibitors of HER2WT and HER2YVMA.

HER2 overexpression and amplification have been identified as oncogenic drivers, and the development of therapies to treat tumors harboring these markers has received considerable attention. Activation of HER2 signaling and subsequent cell growth can also be induced by HER2 mutations, including the common YVMA insertion in exon 20 within the kinase domain. Enhertu is currently the only approved treatment for HER2 mutant tumors in NSCLC. TKIs tested in this space have suffered from off-target activity, primarily due to EGFRWT inhibition or attenuated activity against HER2 mutants. The goal of this work was to identify a TKI that would provide robust inhibition of oncogenic HER2WT and HER2 mutants while sparing EGFRWT activity. Herein, we describe the development of a potent, covalent inhibitor of HER2WT and the YVMA insertion mutant while providing oral bioavailability and avoiding the inhibition of EGFRWT.

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

BackgroundExtramammary 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.MethodsImmunohistochemical staining on the scrotal wall tumor and bone marrow metastasis demonstrated HER2 overexpression. Whole genome sequencing of the tumor and matched blood was performed.ResultsNotable 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 (TGFβ) (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.ConclusionWhole 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.

Unraveling the synergistic mechanisms of pyrotinib in combination with trastuzumab: Insights from the PHILA trial.

e13015 Background: There are many options for the treatment of advanced HER2-positive breast cancer. The results of PHILA study suggest that pyrotinib, trastuzumab and docetaxel may be considered as a potential first line treatment for patients with untreated HER2-positive metastatic breast cancer. We aimed to investigate the synergistic mechanisms of pyrotinib plus trastuzumab and compare them to trastuzumab plus pertuzumab, providing further insights for the PHILA trial. Methods: The efficacy of combination treatments was detected by cell vitality assay, Western blot and immunohistochemistry. The relevant mechanism was examined by flow cytometry and co-immunoprecipitation. Cell-derived xenografts and TUBO tumor model were utilized to evaluate the anti-tumor activity of rational combinations. Next-generation sequencing of circulating tumor DNA from a cohort of 18 patients in the PHILA trial was performed to evaluate molecular alterations associated with clinical response. Results: We demonstrated that pyrotinib plus trastuzumab superiorly inhibited cell growth than trastuzumab plus pertuzumab in models of HER2-dependent breast cancer. In addition to inhibiting HER family phosphorylation, pyrotinib plus trastuzumab synergistically reduced membrane HER2 levels by inducing receptor ubiquitination and internalization via HSP90 dissociation, which resulted in a comprehensive blockade of HER signaling pathway. Moreover, TUBO tumor model was utilized to further confirm the synergistic effects of pyrotinib and anti-neu antibody on HER2 signaling cascade. In both treatment groups of PHILA study, patients with aberrant mutations in HER2 signaling cascade showed a significantly shorter median progression-free survival compared to individuals with wild-type pathway. Correspondingly, in models of HCC1954 breast cancer cell harboring PIK3CA H1047R mutation, we did not observe a synergy between pyrotinib and trastuzumab. Conclusions: Pyrotinib and trastuzumab synergistically achieve the comprehensive blockade of HER signaling pathway in HER2-dependent breast cancer. Patients with advanced HER2-positive breast cancer, who are addicted to HER2 signaling cascade, could be considered for pyrotinib in combination with trastuzumab and docetaxel as an alternative first line treatment.

Recurrence score gene axes scores and outcomes by race and ethnicity in the RxPONDER trial.

515 Background: Racial inequities in breast cancer outcomes remain a significant healthcare concern. In a previous analysis of the RxPONDER trial by race/ethnicity, we showed that non-Hispanic Black (NHB) women have worse outcomes compared to non-Hispanic Whites (NHW) despite similar 21-gene recurrence scores (RS). The RS is determined by an assay consisting of 16 cancer-related genes involved in invasion, ER and HER2 signaling, and proliferation. To provide a better understanding of the differences in underlying tumor biology amongst different racial/ethnic groups, we analyzed RS gene axes scores amongst each group and associations with outcomes. Methods: A total of 3,102 women were included: Hispanic (15.5%), NHB (4.7%), Asian (9.5%), and NHW (70.2%). The primary outcome was invasive disease-free survival (IDFS). This analysis extends median follow-up from 5 to 7 years and evaluates gene axes scores that are components of the RS by race/ethnicity. Impact of proliferation, ER, GRB7 (HER2), and invasion axes scores on IDFS was evaluated in Cox regression models. Results: There were no differences in RS distribution across racial/ethnic groups, and RS remained prognostic for each group with no significant variation in RS prognostic value. However, NHBs were noted to have significantly higher proliferation axis scores than NHWs (p&lt;0.001); HER2 axis scores was higher for Asians than NHWs (p&lt;0.001); and Hispanics had both higher HER2 (p=0.002) and proliferation (p=0.02) axes scores compared to NHWs. These results remained statistically significant after adjusting for age. Relative to NHWs, IDFS was worse for NHBs (HR 1.41; 95% CI 0.98-2.03) and better for Asians (HR 0.63; 95% CI 0.43-0.91) in unadjusted analysis. Adjusting for treatment arm, age, grade, menopausal status, proliferation, ER and HER2 axes scores attenuated the impact of race on IDFS for NHBs (HR 1.22; 95% CI 0.84-1.76), although the findings were unchanged for Asians (HR 0.64; 95% CI 0.44-0.93; Table). In a multivariable model, proliferation axis (HR 1.56; 95% CI 1.35-1.80) and ER axis (HR 0.81; 95% CI 0.71-0.93) were prognostic for IDFS. Conclusions: RS gene axes scores differ by race/ethnicity with higher proliferation axis scores noted in NHBs, which could partially explain their inferior outcomes noted in RxPONDER. These findings suggest that tumor biology is indeed important, however, we must dig deeper to uncover intricate factors that contribute to disparities, which is key to designing comprehensive strategies to address them. Clinical trial information: NCT01272037 . [Table: see text]

INAVO122: A phase III study of maintenance inavolisib or placebo + pertuzumab + trastuzumab following induction with pertuzumab + trastuzumab + a taxane in patients (pts) with PIK3CA-mutated, HER2-positive advanced breast cancer (HER2+ aBC).

TPS1124 Background: The PI3K pathway plays a crucial role in HER2 signaling. Somatic mutations of PIK3CA, the gene that encodes the PI3K p110α subunit, may induce resistance to HER2-targeted therapies and are associated with poorer clinical outcomes (Swain SM, et al. SABCS 2022; P2-11-07). Inavolisib, a potent p110α-selective inhibitor that induces degradation of mutant p110α, has shown antitumor activity in PIK3CA-mutated HER2+ BC and long-term tolerability with early intervention for common on-class toxicities, including hyperglycemia, diarrhea, and stomatitis (Jhaveri KL, et al. SABCS 2023; GS03-13, Bedard P, et al. ASCO 2022; 1052). The current study will assess the efficacy and safety of maintenance inavolisib + fixed-dose combination of pertuzumab + trastuzumab for subcutaneous injection (PH FDC SC) after first-line (1L) induction treatment in pts with PIK3CA-mutated, HER2+ aBC. Methods: INAVO122 (NCT05894239) is a multicenter, randomized, international, double-blind, placebo-controlled study. Pts will be enrolled for: 1L induction treatment if they are receiving/will receive PH + a taxane; or for maintenance treatment if they completed induction treatment per standard of care. In the maintenance phase, pts will be randomized 1:1 to receive inavolisib (9 mg orally once daily; 21-day cycles) + PH FDC SC (every 3 weeks), or placebo + PH FDC SC. Study treatment will continue until disease progression (PD), unacceptable toxicity, death, consent withdrawal, or at the investigator’s (INV) discretion. Enrolled pts must have centrally determined HER2+, PIK3CA-mutated tumors, with documented hormone receptor status per local assessment, and be disease-free for ≥6 months from completion of neoadjuvant/adjuvant HER2-targeted treatment. They must not have received any non-hormonal treatment for aBC prior to induction, and, at screening, fasting glucose must be &lt;126 mg/dL and HbA1c &lt;6.4%. To be randomized, pts must have completed induction therapy without PD and show left ventricular ejection fraction ≥50%. The primary endpoint is INV-assessed progression-free survival. Secondary endpoints are overall survival; INV-assessed objective response rate, duration of response, clinical benefit rate, and time to second disease progression; health-related quality of life; safety; and pharmacokinetics. The primary endpoint analysis will utilize a two-sided stratified log-rank test at a two-sided significance level of 5%. A stratified Cox proportional hazards model will be used to estimate the hazard ratio between the two treatment arms and its 95% confidence intervals. An independent data monitoring committee will be in place for safety. Target randomization is ~230 pts; this study is currently recruiting (15 pts enrolled). Encore from SABCS 2023 (PO2-19-09). Clinical trial information: NCT05894239 .

Multiomic analysis in ovarian clear cell carcinoma to gain insight into biology and therapeutic opportunities.

e17540 Background: Ovarian clear cell carcinoma (OCCC) is a rare subtype with distinct histologic and molecular features. The prognosis of advanced/recurrent OCCC treated with standard of care surgery and platinum-based chemotherapy remains poor due to inherent chemoresistance. Therefore, there is an urgent need to identify novel biological insights and personalized treatment approaches to improve outcomes. Methods: Participants were referred to the SMMART Program at the OHSU Knight Cancer Institute. Archival or fresh tissue was obtained from metastatic sites and processed through a multiomics platform that included immunohistochemistry (Ki67, HER2, CD4, CD8, PD-L1), fluorescent in-situ hybridization, targeted next-generation sequencing panel (225 genes), whole transcriptomic sequencing, chromosomal microarray, and multiplexed analysis of 67 key cancer proteins and phosphoproteins on the Nanostring GeoMx Digital Spatial Profiler. Results: 5 participants were enrolled with an average age of 62 years (range 52-72). Therapeutically relevant findings included detectable HER2 expression by IHC (2+, N=2; 3+, N=2), HER2 amplification by FISH (N=2), and high HER2 and phospho-HER2 protein expression compared to a breast cancer cohort (phospho-HER2 supports active HER2 signaling in the tumor cells). Additional findings include TMB &lt;10 muts/Mb (N=5), microsatellite stable (N=5), Ki67 40-60% (N=4), mild to moderate CD4 and/or CD8 infiltration (N=4), PD-L1 &gt;1% (N=3), low homologous recombination deficiency score (N=4), chromosomal losses including ATM, SMAD4, RB1, and TP53, and single nucleotide variations in ARID1A (N=4). Two participants with HER2 expression were treated with off-label trastuzumab deruxtecan for 6 or 7 cycles yielding significant clinical benefit. Participant A (HER2 = 3+, FISH negative) had an exceptional response while Participant B (HER2 = 2+, FISH amplified) had stable disease. The toxicity profile was consistent with literature. Conclusions: Our OCCC cohort revealed elevated HER2 expression with or without genomic amplification in 4/5 cases. Two participants experienced clinical benefit when treated with trastuzumab deruxtecan, supporting further exploration of HER2 antibody drug conjugates in this aggressive disease. More study is needed to determine the frequency of HER2 overexpression and amplification in OCCC, the importance of HER2 on OCCC pathophysiology, and the therapeutic benefit of targeting HER2 in this population.

An Open-Label Phase II Trial NCT03812393 to Evaluate the Efficacy and Safety of Neoadjuvant Neratinib Followed by Weekly Paclitaxel and Carboplatin Plus Neratinib in Early-Stage Triple-Negative Breast Cancer (TNBC) Patients Who Exhibit Enhanced HER2 Signaling by Live Cell HER2 Signaling Transduction Analysis (FACT-2)

An Open-Label Phase II Trial NCT03812393 to Evaluate the Efficacy and Safety of Neoadjuvant Neratinib Followed by Weekly Paclitaxel and Carboplatin Plus Neratinib in Early-Stage Triple-Negative Breast Cancer (TNBC) Patients Who Exhibit Enhanced HER2 Signaling by Live Cell HER2 Signaling Transduction Analysis (FACT-2)

Molecular Mechanism of Breast Cancer and Predisposition of Mouse Mammary Tumor Virus Propagation Cycle.

Over the past few decades, women have been troubled by grave diseases such as breast cancer, which are biologically and molecularly classified as hereditary diseases. Even though the risk of other cancers is relatively different and the downstream pathway of genetic mutation differs from breast cancer, the continued transformation of genes such as BRCA1 and BRCA2 leads to breast cancer malignancy. Notably at the molecular level, a parallel connection between the normal growth of breast and the progression of mammary cancer where the breast cancer stem cells play a crucial role in the advancement of mammary carcinoma. Arguably, several significant signaling pathways, for instance, ER signaling, HER2 signaling, and Wnt signaling control the typical breast development as well as breast stem cells, thereby cell proliferation, cell differentiation, and cell motility are involved. Incidentally, the Mouse Mammary Tumor Virus (MMTV) is notable among the unexplained viral components influenced by virus-corrupting mammary carcinomas. According to the genesis, MMTV proviral DNA is integrated into mammary epithelial cells, and genomic lymphoid cells during viral replication and triggers the progression of cellular oncogenesis. This overview reveals the deadliest theories on breast cancer, molecular mechanisms, and the MMTV transmission cycle. To establish prevention therapies that are both acceptable and efficacious, addressing apprehensions related to the toxicity of these interventions must be a preliminary hurdle to overcome.

Structure and conformational variability of the HER2-trastuzumab-pertuzumab complex

Single particle analysis from cryogenic transmission electron microscopy (cryo-EM) is particularly attractive for complexes for which structure prediction remains intractable, such as antibody-antigen complexes. Here we obtain the detailed structure of a particularly difficult complex between human epidermal growth factor receptor 2 (HER2) and the antigen-binding fragments from two distinct therapeutic antibodies binding to distant parts of the flexible HER2, pertuzumab and trastuzumab (HTP). We highlight the strengths and limitations of current data processing software in dealing with various kinds of heterogeneities, particularly continuous conformational heterogeneity, and in describing the motions that can be extracted from our dataset. Our HTP structure provides a more detailed view than the one previously available for this ternary complex. This allowed us to pinpoint a previously overlooked loop in domain IV that may be involved both in binding of trastuzumab and in HER2 dimerization. This finding may contribute to explain the synergistic anticancer effect of the two antibodies. We further propose that the flexibility of the HTP complex, beyond the difficulties it causes for cryo-EM analysis, actually reflects regulation of HER2 signaling and its inhibition by therapeutic antibodies. Notably we obtain our best data with ultra-thin continuous carbon grids, showing that with current cameras their use to alleviate particle misdistribution is compatible with a protein complex of only 162 kDa. Perhaps most importantly, we provide here a dataset for such a smallish protein complex for further development of software accounting for continuous conformational heterogeneity in cryo-EM images.