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PubMed2026

A study on the mechanism of action of B7H4 in HER2-positive gastric cancer and its sensitivity to trastuzumab therapy.

BACKGROUND: Human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC) is characterized by high malignancy and a poor prognosis. Trastuzumab is the first-line targeted therapy for this disease, but the frequent development of primary and acquired resistance severely compromises treatment efficacy and impedes improvements in patient outcomes. B7H4 is a critical negative immune checkpoint molecule that has been demonstrated to contribute to tumor progression and targeted therapy resistance in multiple cancers. However, the specific mechanisms by which B7H4 regulates sensitivity to trastuzumab in HER2-positive GC remain unclear. This study aims to investigate the expression and biological functions of B7H4 in HER2-positive GC, elucidate the molecular mechanisms underlying B7H4-mediated trastuzumab resistance, and thereby provide a theoretical basis for targeted resistance intervention and therapeutic optimization for this malignancy. METHODS: The study began with an analysis of The Cancer Genome Atlas (TCGA) database and immunohistochemical staining of tissue sections to assess the expression levels of B7H4 and HER2, as well as the correlation between their expression. Furthermore, the correlation between B7H4 expression and various pathological parameters in patients with HER2-positive GC was analysed. Western blot analysis was used to screen for co-expressing cells, and short hairpin RNA (shRNA) was employed to knockdown B7H4. The effects of B7H4 knockdown on the proliferation, migration and invasion of HER2-positive GC cells were assessed using colony formation assays, Cell Counting Kit-8 (CCK-8) assays, cell scratch assays and Transwell assays, respectively. RNA sequencing (RNA-Seq) was utilised to analyse the biological processes and signalling pathways regulated by B7H4 and to detect relevant biomarkers. Colony formation assays and CCK-8 assays were employed to evaluate the therapeutic sensitivity of trastuzumab to HER2-positive GC cells following B7H4 knockdown. RESULTS: Analysis of the TCGA database and immunohistochemical staining of tissue sections revealed that B7H4 and HER2 were co-expressed in GC tissues, and their expression levels were positively correlated. Clinical correlation analysis revealed that B7H4 expression was significantly associated with tumor size, grade, depth of invasion, lymph node metastasis, distant metastasis, vascular invasion and nerve invasion in HER2-positive GC patients. Western blot analysis demonstrated co-expression of B7H4 and HER2 in NCI-N87 cells. Knockdown of B7H4 resulted in varying degrees of inhibition of proliferation, migration and invasion in NCI-N87 cells. RNA-seq results indicated that B7H4 knockdown affected biological processes such as cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT), and was significantly associated with the nuclear factor κB (NF-κB) signalling pathway. Knockdown of B7H4 significantly enhanced the sensitivity of HER2-positive GC cells to trastuzumab. CONCLUSIONS: B7H4 is highly expressed in HER2-positive GC and is associated with poor prognosis. B7H4 promotes tumor cell proliferation, migration and invasion by activating the NF-κB signalling pathway and driving the EMT process. B7H4 expression influences the sensitivity of HER2-positive GC cells to trastuzumab; inhibition of B7H4 significantly enhances the antitumor efficacy of trastuzumab.

B7H4↗

PubMed2025

Molecular features influencing clinical outcome of advanced HER2-positive gastric cancer receiving trastuzumab plus chemotherapy.

BACKGROUND: Less than half of the human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC) patients respond to trastuzumab plus chemotherapy, and the outcomes are unsatisfactory. Understanding the underlying mechanisms remains crucial for identifying patients who are more likely to benefit from treatment. PATIENTS AND METHODS: We performed targeted DNA sequencing on paired pre-treatment and progressive tumour tissues from 22 HER2-positive advanced GC patients undergoing first-line treatment with trastuzumab and chemotherapy. Clinicopathological and genomic characteristics were assessed for the correlation with clinical outcomes. RESULTS: A performance status (PS) of 0-1 was associated with improved progression-free survival (PFS) and overall survival (OS) than a PS of 2. Poorly differentiated tumours exhibited shorter PFS than moderate or moderate-poor ones. Pre-treatment amplification of MYC or TOP2A gene was association with increased PFS, and suggested a potential benefit for OS. Patients with higher tumour mutation burden (TMB) experienced significantly worse PFS, while higher chromosome instability (CIN) appeared to be correlated with longer PFS. Compared to non-responders, responders had a higher CIN but similar TMB and intratumoural heterogeneity (ITH). PS and MYC amplification emerged as independent factors related to PFS according to multivariate survival analysis. Additionally, after treatment, TMB significantly increased in non-responders, while CIN significantly decreased in responders. CONCLUSIONS: Pre-treatment MYC amplification and PS were independently associated with clinical outcomes in HER2-positive advanced GC patients treated with first-line trastuzumab plus chemotherapy. Dynamic post-treatment changes in TMB and CIS provide valuable insights into the relationship between therapeutic response and distinct evolutionary trajectories.

Humans↗

PubMed2026

Efficacy and Genomic Analysis of HER2-Mutant Metastatic Triple-Negative Breast Cancer Treated with Neratinib Alone or with Trastuzumab in the SUMMIT Basket Trial.

PURPOSE: Human epidermal growth factor receptor 2 (HER2) mutations occur in 1% to 3% of triple-negative breast cancers (TNBC), representing a novel target for biomarker-directed treatment. In the SUMMIT basket trial (NCT01953926), patients with HER2-mutant, metastatic TNBC received neratinib (240 mg/day) or neratinib + trastuzumab (N + T; neratinib 240 mg/day, intravenous trastuzumab 8 mg/kg initially and then 6 mg/kg every 3 weeks). We report final results from the neratinib and N + T TNBC cohorts. PATIENTS AND METHODS: Primary endpoint: investigator-assessed objective response rate at first postbaseline tumor assessment (ORRfirst); secondary endpoints included confirmed ORR by investigator, clinical benefit rate (CBR), and progression-free survival (PFS); exploratory endpoint included circulating tumor DNA (ctDNA) collected at baseline, during treatment, and at the end of treatment. RESULTS: Twenty-seven patients were enrolled between July 2014 and September 2021. Confirmed ORRs were 40% [95% confidence interval (CI), 12.2-73.8] for neratinib (n = 10) and 35.3% (95% CI, 14.2-61.7) for N + T (n = 17). CBRs were 40% (95% CI, 12.2-73.8) and 47.1% (95% CI, 23-72.2), respectively; median PFS times were 2.89 (95% CI, 0.95-5.52) and 6.24 months (95% CI, 2.10-8.18), respectively. HER2 mutation variant allele frequencies in ctDNA from patients with response or stable disease decreased upon treatment and increased upon progression. Serial ctDNA sequencing revealed emergence or increase in on-pathway (ERBB3) and off-pathway (KRAS and TP53) mutations. The most common treatment-emergent adverse events were diarrhea, nausea, and constipation. CONCLUSIONS: N + T in patients with HER2-mutant metastatic TNBC seemed to prolong responses versus neratinib alone, representing a novel approach for patients with biomarker-defined metastatic TNBC. Based on these and previously published data, neratinib-based combinations are endorsed by the National Comprehensive Cancer Network guidelines for patients with hormone receptor-positive or -negative metastatic breast cancer with activating HER2 mutations. See related commentary by Lloyd et al., p. 3715.

Adult↗

PubMed2026

Patient-reported outcomes from the TBCRC 022 study of neratinib and ado-trastuzumab emtansine for HER2-positive breast cancer brain metastases.

PURPOSE: In TBCRC 022 (NCT01494662), neratinib and ado-trastuzumab emtansine (T-DM1) demonstrated intracranial activity among patients with HER2-positive breast cancer brain metastases. However, gastrointestinal (GI) toxicities-particularly diarrhea-were common, potentially impacting quality of life. Clinician-reported adverse event (CTCAE) grading may underestimate the patient experience. We report GI toxicities using patient-reported outcomes (PROs) in TBCRC's neratinib-T-DM1 cohort. METHODS: Patients received neratinib (160 mg daily) and T-DM1 (3.6 mg/kg IV every 21 days). A pre-planned analysis assessed patient-reported GI toxicities during Cycles 1-4 using the Patient-reported Outcomes Measurement Information System (PROMIS) GI Diarrhea scale, Systemic Therapy-Induced Diarrhea Assessment Tool (STIDAT), and PRO-CTCAE. Descriptive statistics and linear mixed effects models evaluated symptom trajectories over time. We evaluated agreement for PRO and clinician-reported data. RESULTS: Forty-four patients enrolled; all completed ≥1 PRO. GI symptom burden increased over Cycles 1-3. PROMIS scores worsened significantly by Cycle 2, with a peak mean increase of 6.62 (95% confidence interval (CI): 2.67-10.59; p = 0.002) at Cycle 3. STIDAT scores also worsened by Cycle 3 (mean change 0.50; 95%CI: 0.11-0.90; p = 0.015). Based on maximum PRO-CTCAE scores, moderate-to-severe symptoms were reported by 20.5% (diarrhea), 24.4% (appetite loss), and 41.0% (constipation). Agreement between PRO-CTCAE and clinician-reported CTCAE was low (kappa <0.2) with clinicians reporting less toxicity. PROMIS and STIDAT scores were significantly correlated. CONCLUSION: This GI-focused PRO analysis highlights the value of PROs in capturing patient-experienced toxicities that impact quality of life yet are underestimated by clinicians. Incorporating PROs into clinical trials can inform supportive care and prophylactic strategies.

Humans↗

PubMed2026

Trastuzumab deruxtecan rechallenge in HER2-positive metastatic breast cancer: EN-SEMBLE.

BACKGROUND: Trastuzumab deruxtecan (T-DXd) is a key treatment for HER2-positive metastatic breast cancer (mBC); however, data on T-DXd rechallenge remain limited. PATIENTS AND METHODS: This post-hoc subgroup analysis evaluated T-DXd rechallenge in patients with HER2-positive mBC using data from EN-SEMBLE, a nationwide cohort study in Japan (N = 664). RESULTS: Twenty-six patients were included. Median real-world progression-free survival, real-world time to treatment failure, and overall survival were 6.5, 4.9, and 14.2 months, respectively. The objective response rate was 27%. Patients who discontinued initial T-DXd without progressive disease had numerically longer real-world progression-free survival. No interstitial lung disease occurred during rechallenge. CONCLUSION: T-DXd rechallenge may have clinical activity in selected patients with HER2-positive mBC. CLINICAL TRIAL REGISTRATION NUMBER: jRCT1030220506.

Humans↗

PubMed2026

Trastuzumab Deruxtecan in Metastatic Urothelial Carcinoma with NGS-Detected ERBB2 Amplification: A Four-Patient Real-World Case Series.

Background: Next-generation sequencing (NGS)-detected ERBB2 amplification occurs in a subset of urothelial carcinomas, but its role as a treatment-selection marker for trastuzumab deruxtecan (T-DXd) remains uncertain. Methods: We retrospectively reviewed four patients with metastatic urothelial carcinoma treated with T-DXd in routine practice from 2024. Treatment selection was based on NGS-detected ERBB2 amplification because HER2 immunohistochemistry and in situ hybridization were unavailable. Results: Four men aged 65-76 years received T-DXd: one in the second line and three in the fourth or fifth line. The best radiological responses, abstracted from contemporaneous radiology reports and oncology medical records, were complete response in one patient, partial response in one, and stable disease in two. Three patients had previously received enfortumab vedotin. Documented adverse events included fatigue, anemia, diarrhea, rash, and leukopenia. No interstitial lung disease or pneumonitis was documented in the available records. Conclusions: These observations are descriptive and hypothesis-generating. They do not establish the efficacy or safety of T-DXd or validate ERBB2 amplification as a predictive biomarker, but they support prospective evaluation of genomic ERBB2 amplification when standard HER2 testing is unavailable.

Humans↗

PubMed2025

Trastuzumab Deruxtecan for ERBB2-Mutant Metastatic Non-Small Cell Lung Cancer With or Without Brain Metastases: A Secondary Analysis of Randomized Clinical Trials.

IMPORTANCE: Brain metastases reduce overall survival rates of patients with non-small cell lung cancer (NSCLC); patients with epidermal growth factor receptor 2 (ERBB2 [formerly HER2])-mutant NSCLC are more likely to have baseline brain metastases. Trastuzumab deruxtecan (T-DXd) is an approved ERBB2-directed treatment for previously treated unresectable or metastatic ERBB2-mutant NSCLC. OBJECTIVE: To assess the clinical effectiveness and safety of T-DXd 5.4 mg/kg and 6.4 mg/kg doses in patients with previously treated ERBB2-mutant metastatic NSCLC with or without untreated or previously treated stable brain metastases. DESIGN, SETTING, AND PARTICIPANTS: This post hoc secondary analysis pooled patients from the DESTINY-Lung01 (data cutoff date: December 3, 2021) and DESTINY-Lung02 (data cutoff date: December 23, 2022) clinical trials by T-DXd dose (5.4 mg/kg and 6.4 mg/kg). DESTINY-Lung01 was a multicenter, open-label, 2-cohort, nonrandomized phase 2 study, while DESTINY-Lung02 was a dose-blinded, multicenter, 2-cohort, randomized phase 2 study. Participants had a previously treated ERBB2-mutant metastatic NSCLC with or without untreated or previously treated stable brain metastases at baseline. All statistical analyses were performed from April 2023 to October 2024. INTERVENTION: Patients received a T-DXd dose of either 5.4 mg/kg or 6.4 mg/kg intravenously every 3 weeks. MAIN OUTCOME AND MEASURE: Systemic and intracranial effectiveness by blinded independent central review using RECIST (Response Evaluation Criteria in Solid Tumors) version 1.1, sites of progression, and safety. RESULTS: This analysis included 102 patients in the T-DXd 5.4-mg/kg dose group (65 females [64%]; median [range] age, 57.5 [37.0-83.0] years and 59.5 [30.0-79.0] years in patients with and without brain metastases, respectively) and 141 patients in the T-DXd 6.4-mg/kg dose group (94 females [67%]; median [range] age, 62.5 [29.0-88.0] years and 59.0 [27.0-83.0] years in patients with and without brain metastases, respectively). In each group, 31% (32 of 102) and 38% (54 of 141) of patients, respectively, had baseline brain metastases and 53% (17 of 32) and 44% (24 of 54), respectively, received prior brain metastasis treatment. In patients with and without brain metastases, systemic confirmed objective response rates (ORRs) were 47% (15 of 32; 95% CI, 29%-65%) and 50% (35 of 70; 95% CI, 38%-62%), respectively, with the T-DXd 5.4-mg/kg dose, and 50% (27 of 54; 95% CI, 36%-64%) and 59% (51 of 87; 95% CI, 48%-69%) with the T-DXd 6.4-mg/kg dose. Median progression-free survival was 7.1 (95% CI, 5.5-9.7) months in the T-DXd 5.4-mg/kg dose group and 7.1 (95% CI, 4.5-9.6) months in the T-DXd 6.4-mg/kg dose group of patients with baseline brain metastases. Among patients with measurable baseline brain metastases, intracranial confirmed ORRs were 50% (7 of 14; 95% CI, 23%-77%) with the T-DXd 5.4-mg/kg dose and 30% (9 of 30; 95% CI, 15%-49%) with the T-DXd 6.4-mg/kg dose. At both doses, the safety profile of T-DXd was generally manageable, regardless of baseline brain metastases, favoring the T-DXd 5.4 mg/kg dose. CONCLUSIONS AND RELEVANCE: In this secondary analysis, T-DXd at the approved dose of 5.4 mg/kg showed antitumor activity in patients with previously treated ERBB2-mutant metastatic NSCLC with or without brain metastases. This finding supports T-DXd 5.4 mg/kg use in this population.

Adult↗

PubMed2026

Neoadjuvant Paclitaxel, Trastuzumab, and Pertuzumab for Stage II to III, ERBB2-Positive Breast Cancer: A Secondary Analysis of the DAPHNe Trial.

IMPORTANCE: The neoadjuvant combination of paclitaxel, trastuzumab, and pertuzumab (THP) represents a promising abbreviated regimen for early-stage ERBB2-positive breast cancer, but long-term outcomes and the role of ultrasensitive circulating tumor DNA (ctDNA) monitoring remain incompletely defined. OBJECTIVE: To assess 5-year outcomes and characterize ctDNA dynamics with an ultrasensitive assay in patients with ERBB2-positive breast cancer receiving neoadjuvant THP. DESIGN, SETTING, AND PARTICIPANTS: This study was a prespecified secondary analysis of the prospective, single-arm, investigator-initiated phase 2 DAPHNe nonrandomized clinical trial. Patients were enrolled in the DAPHNe trial from November 2018 to January 2020. The trial took place at a multicenter academic cancer center and affiliated community practices. Participants included patients with stage II to III ERBB2-positive breast cancer receiving neoadjuvant THP for 12 weeks. Ultrasensitive ctDNA analyses were performed in patients with available tumor tissue and serial plasma samples. The secondary analysis was conducted between between March 2023 and April 2025. INTERVENTIONS: Neoadjuvant THP administered for 12 weeks, followed by surgery and adjuvant therapy guided by pathologic response. MAIN OUTCOMES AND MEASURES: Main outcomes included 5-year event-free survival, recurrence-free interval (RFI), distant RFI, and overall survival. ctDNA detection and clearance were assessed using a whole-genome-based, tumor-informed ultrasensitive assay at 4 predefined time points (baseline, preoperative, postoperative, and late adjuvant). RESULTS: The overall trial cohort included 98 patients (median [IQR] age, 49.5 years [24.0-78.0 years]; 97 female patients [99.0%]; 1 male patient [1.0%]), with mostly stage 2 disease (91 patients [92.9%]) and hormone receptor-positive tumors (65 patients [66.3%]). With a median (IQR) follow-up of 5.2 (5.0-5.4) years, the 5-year event-free survival was 99% (95% CI, 97%-100%), the 5-year RFI was 98% (95% CI, 93%-100%), the 5-year distant RFI was 100% (95% CI, 100%-100%), and the 5-year overall survival was 99% (95% CI, 97%-100%). Among 57 patients included in ctDNA analyses, baseline ctDNA was detected in 51 individuals (89.5%). After neoadjuvant therapy, ctDNA clearance occurred in 49 of 51 patients (96.1%), with only 2 individuals (3.9%) remaining ctDNA-positive preoperatively; detectability remained low (<10%) during postoperative follow-up. One single patient experienced a local recurrence, with ctDNA detected at time of recurrence and cleared following surgical resection. CONCLUSIONS AND RELEVANCE: In this secondary analysis of the DAPHNe nonrandomized clinical trial, neoadjuvant THP was associated with excellent long-term outcomes in patients with early-stage ERBB2-positive breast cancer. Ultrasensitive ctDNA analyses demonstrated high baseline detection rates and near-universal clearance after abbreviated neoadjuvant therapy, supporting further investigation of ctDNA-guided de-escalation strategies in this setting. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03716180.

Humans↗

PubMed2026

HER2DX genomic assay in HER2-positive early breast cancer treated with trastuzumab and pertuzumab: A correlative analysis from a real-world cohort.

BACKGROUND: HER2DX genomic assay is a genomic tool developed for personalizing care in early-stage HER2-positive breast cancer. This real-world analysis examines its associations with pathological complete response (pCR) and invasive disease-free survival (IDFS) following trastuzumab- and pertuzumab-based neoadjuvant therapy. MATERIALS AND METHODS: Retrospective, observational, single-center study of 156 patients with stage I-III HER2-positive breast cancer treated with dual HER2 blockade-based neoadjuvant therapy between February 2015 and May 2022 at University Hospital A Coruña. HER2DX and clinicopathological variables were assessed in pretreatment tumor biopsies. Statistical analyses included Fisher's exact test, logistic regression, Cox proportional hazards models, and Kaplan-Meier estimates. RESULTS: HER2DX was performed in 111 tumors (71.2%). Overall pCR rate was 51.3%. Hormone receptor-positive disease was significantly associated with lower pCR (odds ratio [OR] 0.25, 95% CI 0.11-0.50; p < 0.001), whereas HER2 immunohistochemistry 3+ showed a non-significant trend toward higher pCR (OR 2.95, 95% CI 0.96-11.08; p = 0.075). Median IDFS was not reached, but hormone receptor-positive tumors showed better outcomes (hazard ratio [HR] 3.67, 95% CI 1.02-13.32; p = 0.004 by log-rank). The association between HER2DX pCR score and pCR appeared heterogeneous. The continuous score was significantly associated with pCR in univariable analysis, not in multivariable model. In contrast, medium-high HER2DX pCR category showed significantly higher pCR rates than low category (OR 4.83, 95% CI 1.72-14.65; p = 0.004). The continuous HER2DX risk score was independently associated with IDFS (HR 2.84, 95% CI 1.24-6.48; p = 0.010). CONCLUSIONS: In this cohort, HER2DX scores were associated with pCR and IDFS, supporting previous evidence and highlighting potential role in treatment stratification.

Humans↗

PubMed2026

DESTINY-Lung06: trastuzumab deruxtecan and pembrolizumab as first-line treatment for HER2-overexpressing, PD-L1 TPS <50% NSCLC.

Non-small cell lung cancer (NSCLC) that overexpresses human epidermal growth factor receptor 2 (HER2) is associated with poor prognosis, and no HER2-targeting therapies for HER2-overexpressing NSCLC are currently approved in the first-line setting. Pembrolizumab plus pemetrexed and platinum-based chemotherapy is a recommended first-line treatment option for nonsquamous NSCLC with no actionable genomic alterations. However, improved outcomes with pembrolizumab-based therapies correlate with higher programmed death-ligand 1 (PD-L1) levels, underscoring the need for more targeted treatment options for patients with lower PD-L1 tumor proportion scores (TPS; <50%). DESTINY-Lung06 is a multicenter, open-label, randomized, phase III trial evaluating the efficacy and safety of trastuzumab deruxtecan (T-DXd) in combination with pembrolizumab in the first-line setting in patients with HER2-overexpressing (≥25% moderate/strong membrane staining), PD-L1 TPS <50% NSCLC. Planned enrollment will be approximately 686 patients randomly assigned to either T-DXd 5.4 mg/kg with pembrolizumab 200 mg intravenously every 3 weeks (Q3W) or pembrolizumab 200 mg plus pemetrexed 500 mg/m2 with platinum-based chemotherapy (cisplatin 75 mg/m2 or carboplatin under the concentration-time curve 5 mg min/mL) intravenously Q3W. Progression-free survival by blinded independent central review and overall survival are the primary and key secondary endpoints of the study, respectively.Clinical trial registration: www.ClinicalTrials.gov identifier is NCT06899126; EudraCT identifier is 2024-515658-26-00.

First-line↗

PubMed2026

Trastuzumab deruxtecan plus pertuzumab in first-line HER2-positive advanced/metastatic breast cancer.

Explore the source record for details and available documents.

Letter↗

PubMed2026

Eribulin versus taxane as first-line chemotherapy combined with dual HER2 blockade in patients with HER2-positive locally advanced or metastatic breast cancer: final survival outcomes of the JBCRG-M06/EMERALD study.

BACKGROUND: The phase III JBCRG-M06/EMERALD study was the first to show noninferior progression-free survival (PFS) of eribulin to taxane, combined with dual human epidermal growth factor receptor 2 (HER2) blockade (trastuzumab plus pertuzumab), as a first-line treatment for HER2-positive locally advanced breast cancer or metastatic breast cancer (LABC/MBC). We report final survival outcomes and biomarker analyses of the EMERALD trial. PATIENTS AND METHODS: Patients with HER2-positive LABC/MBC were randomly assigned 1:1 to either eribulin or physician-choice taxane (docetaxel or paclitaxel), both combined with trastuzumab plus pertuzumab, as first-line chemotherapy. PFS and overall survival (OS) were assessed through 30 June 2023 for PFS and 31 December 2024 for OS. Survival outcomes were compared between the eribulin and taxane groups and according to circulating tumor DNA (ctDNA) detection of PIK3CA mutations (PIK3CAm+; E542K, E545K, H1047R, and N345K single nucleotide variants) or HER2 amplification (HER2 amp+; ERBB2 copy number >2.5). RESULTS: Median OS was 78.5 months [95% confidence interval (CI) 64.3-not reached (NR)] for eribulin and was NR for taxane, with a hazard ratio of 1.25 (95% CI 0.92-1.71, log-rank P = 0.19). The 60-month OS rates were 59.7% and 65.2% for eribulin and taxane, respectively. Median OS and 60-month OS rates were numerically lower in ctDNA PIK3CAm+ patients, and greater in ctDNA HER2 amp+ patients for all patients and with stratification by treatment group. There were no statistical interactions between treatment group with either ctDNA PIK3CAm or ctDNA HER2 amp status. Similar patterns were observed for PFS. CONCLUSION: Final survival analysis revealed that median OS exceeded 6 years with eribulin or physician-choice taxane, combined with trastuzumab plus pertuzumab, as first-line chemotherapy for HER2-positive LABC/MBC, with no significant differences between the two groups. ctDNA PIK3CAm+ status was a poor prognostic factor. ctDNA HER2 amp+ was associated with longer survival.

Aged↗

PubMed2026

Associations of TILs and genomic alterations in HER2+ early breast cancer.

This study investigated the associations between tumor-infiltrating lymphocytes (TILs), genomic features, and prognosis in HER2+ early breast cancer (EBC) patients receiving adjuvant trastuzumab. We retrospectively analyzed 864 HER2+ EBC patients from Shanghai Ruijin Hospital (2009-2017). The optimal threshold of TILs for predicting disease-free survival (DFS) and overall survival (OS) was explored. Whole-exome sequencing (WES) on 261 tumors assessed the mutational profiles, tumor mutational burden (TMB), and copy number alteration (CNA). Associations between these genomic features, TIL levels, and prognosis were further evaluated. TILs showed a right-skewed distribution (median: 15%, IQR: 1-30%), and higher TIL levels were significantly associated with hormone receptor negativity and high histologic grade (P < 0.001). A 15% TIL threshold optimally predicted prognosis, with low-TIL (≤15%, 63.0%) patients showing inferior DFS (HR: 1.63, P = 0.009) and OS (HR: 2.12, P = 0.037). WES identified frequent mutations in TP53 (62.8%), PIK3CA (34.5%), and BRCA2 (9.6%). A higher TIL density was observed in TP53-wild-type, low-TMB or low-CNA tumors (P < 0.05). PIK3CA mutations conferred a significant DFS advantage. Integrating TIL level with PIK3CA or BRCA2 mutational status yielded distinct DFS trajectories (log-rank P = 0.023 and 0.040, respectively); patients with both high TIL levels and either PIK3CA or BRCA2 mutations had the most favorable outcomes. Stromal TILs at a 15% cutoff provide robust prognostic information in trastuzumab-treated HER2+ EBC. Integrating TIL levels with PIK3CA or BRCA2 mutational status enables refined risk stratification, offering a practical framework for personalized treatment decisions.

Humans↗

PubMed2026

Quality-of-life assessment in the randomized JBCRG-M06/EMERALD study of eribulin plus dual HER2 blockade in HER2-positive locally advanced or metastatic breast cancer.

BACKGROUND: Although taxanes are a mainstay treatment for locally advanced or metastatic breast cancer (LABC/MBC), they often impair quality of life (QoL). Treatments that avoid taxane-related QoL deteriorations would be valuable. METHODS: The JBCRG-M06/EMERALD trial (NCT03264547, UMIN000027938) compared eribulin with a taxane, each combined with trastuzumab and pertuzumab, in patients with human epidermal growth factor receptor type 2 (HER2)-positive LABC/MBC. QoL was assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Module C30 (EORTC QLQ-C30) version 3.0. QoL deterioration was defined as a decrease in the Global Health Status (GHS) score by ≥ 10 points (minimum clinically important difference), disease progression, or death. RESULTS: QoL data were available for 210 (of 224 randomized) and 205 (of 222 randomized) patients in the eribulin and taxane groups, respectively. The median (95% confidence interval) time to QoL deterioration was 7.16 (6.28-8.34) months in the eribulin group versus 4.57 (4.17-6.14) months in the taxane group, with a hazard ratio of 0.80 (95% confidence interval 0.65-0.98; log-rank P = 0.08). QoL was maintained at 6 and 12 months in greater proportions of the eribulin group (62.7% and 30.5%) compared with the taxane group (43.5% and 25.5%). GHS scores remained stable over time in the eribulin group. GHS deteriorated between weeks 9 and 27 in the taxane group (i.e. during treatment) with subsequent recovery toward baseline. CONCLUSIONS: Eribulin could help avoid the early deteriorations in QoL that occur during taxane therapy and maintain QoL for longer in patents with HER2-positive LABC/MBC receiving trastuzumab and pertuzumab.

Adult↗

PubMed2026

Manual, digital, and AI tumour-infiltrating lymphocyte scoring: a secondary analysis of the APHINITY randomised trial.

BACKGROUND: Stromal tumour-infiltrating lymphocytes (sTILs) are prognostic in early-stage HER2-positive breast cancer, but their role in the context of dual HER2 blockade remains undefined. We evaluated manual, digital, and artificial intelligence (AI)-based sTIL quantification, together with AI-derived spatial metrics, for prognostic and treatment-benefit stratification using tumour samples from the phase 3 APHINITY trial. METHODS: In the APHINITY trial, 4805 patients were randomly assigned to receive chemotherapy plus trastuzumab with pertuzumab or chemotherapy plus trastuzumab with placebo. Median follow-up was 74·1 months (IQR 68·3-75·4). We analysed 4262 haematoxylin and eosin-stained images using manual assessment, an automated digital approach, AI-based lymphocyte quantification (AI percentage lymphocytes), and two AI-derived spatial features (AI-TIL and immune hotspot). Interobserver reproducibility was assessed in 262 randomly chosen tumour samples scored independently by five pathologists. Multivariable Cox models were used to assess associations between TIL levels and invasive disease-free survival (primary outcome in APHINITY), distant recurrence-free interval, and overall survival. The heterogeneity of pertuzumab benefit was evaluated using subgroup analyses, subpopulation treatment effect pattern plot analyses, and nested Cox models with treatment-by-biomarker interaction terms. FINDINGS: Manual scoring showed high interobserver reproducibility (intraclass correlation coefficient 0·84 [95% CI 0·79-0·88]). Concordance between manual and automated methods was modest. AI-based scoring (AI percentage lymphocytes) reclassified 120 (11·6%) of 1035 node-positive tumours from immune-low (by manual scoring) to immune-high; this subgroup of patients showed greater separation of 5-year invasive disease-free survival curves between pertuzumab and placebo groups compared with patients whose tumours were concordantly classified as immune-low by both manual and AI-based approaches. Higher levels of TILs were associated with improved invasive disease-free survival for all sTIL measurement approaches and spatial measurements (hazard ratios [HRs] 0·41-0·93). Pertuzumab was associated with improved invasive disease-free survival at higher sTIL levels across all measurement approaches (HRs 0·36-0·48), but was not associated with higher values of spatial measures. The largest 6-year absolute improvements with pertuzumab were observed in patients with node-positive disease whose tumours scored in the highest level of immune infiltration of manual sTIL scoring (≥70·0%; mean absolute improvement 12·1 percentage points [SD 2·8]). In nested prognostic and predictive models, AI-based immune hotspot scores provided the most consistent additional information when combined with any sTIL measurement (all p<0·010). INTERPRETATION: Standardised manual sTIL scoring was reproducible, and digital and AI-based methods showed consistent prognostic stratification and potential for treatment-benefit stratification despite only modest correlation between platforms. AI spatial metrics provided complementary information beyond sTIL density and could support more scalable immune assessment. Future studies are needed to validate these approaches in independent cohorts and to clarify their clinical utility for stratifying contemporary HER2-directed therapies. FUNDING: None.

Humans↗

PubMed2026

Human Epidermal Growth Factor Receptor-2 positive metastatic salivary duct carcinoma with remarkable response to targeted therapy: a case report and therapeutic implications.

Salivary duct carcinoma (SDC) is a rare and highly aggressive malignancy that frequently overexpresses Human Epidermal Growth Factor Receptor 2 (HER2). Despite the increasing recognition of HER2-targeted strategies, evidence remains limited and largely derived from small trials and case series. We report the case of a middle-aged man with HER2-positive metastatic SDC who achieved near-complete pathologic and radiological response to trastuzumab and docetaxel, enabling surgical resection for locoregional control. This case highlights the role of anti-HER2 therapy as a first-line strategy in SDC and underscores the importance of individualized management plans integrating systemic treatment and locoregional measures.

Humans↗

PubMed2026

Clinical and Molecular Evaluation of HER2-Low and HER2-Ultralow Breast Cancer in the Penelope-B Clinical Trial Cohort.

The DestinyBreast (DB)04 and DB06 trials have shown clinical activity of trastuzumab-deruxtecan (T-DXd) in HER2-low and HER2-ultralow metastatic breast cancer. The identification of HER2-low and HER2-ultralow breast cancer is therefore essential for personalized therapy with T-DXd. We evaluated 723 residual tumors from the Penelope-B trial (NCT01864746) and correlated different levels of HER2 protein expression with prognosis and messenger RNA (mRNA) profiles, including HER2 transcripts. In Penelope-B, 57.68% (n = 417) of 723 residual tumors were HER2 low. The HER2-ultralow category was assigned to 109 (15.08%) tumors, and 197 (27.25%) tumors were completely HER2 negative (HER2 0). In Kaplan-Meier analysis, there were no survival differences among these 3 subgroups. There was no significant difference in HER2 mRNA expression between HER2-0 and HER2-ultralow tumors (P = .08). In contrast, there was a highly significant difference in HER2 mRNA expression between HER2-ultralow and HER2-low tumors (P < .0001) and between HER2-low and HER2-positive tumors (P < .0001). The extracellular protease cathepsin L, which has been suggested as a biomarker for extracellular cleavage of T-DXd, was detectable in all HER2-related subgroups and was a negative prognostic factor for invasive disease-free survival and overall survival (P = .0001) in preneoadjuvant core biopsies. In our study, we were able to characterize HER2 low as a clinically relevant and molecular defined tumor group with significantly increased HER2 expression. In contrast, for HER2 ultralow, we did not observe a defined molecular phenotype, despite the clinically relevant regulatory approval of T-DXd also in the ultralow subgroup. Additional investigations are needed to identify biomarkers beyond HER2 for T-DXd response as a basis for refined criteria for treatment eligibility.

Adult↗

PubMed2026

Spatial proteogenomic profiling uncovers sensitization strategies for antibody-drug conjugate in HER2-positive breast cancer.

Antibody-drug conjugates (ADCs) have transformed the treatment of HER2-positive breast cancer, yet resistance remains poorly understood. Using imaging mass cytometry, we profiled 157 regions of interest comprising 912,360 single cells from 47 HER2-positive/hormone receptor-negative breast cancers treated with SHR-A1811 in the FASCINATE-N trial. Spatial proteomic analyses identified two determinants of ADC response: elevated tumor-cell H3K27ac expression was associated with improved ADC efficacy, whereas collagen-positive fibroblasts mediated resistance. Combining ADC with the histone deacetylase inhibitor chidamide or the collagen-modulating agent losartan produced synergistic antitumor effects in preclinical models. These biomarkers and therapeutic vulnerabilities were independently validated in patients with advanced HER2-positive disease receiving trastuzumab deruxtecan. Moreover, based on these spatial features, we developed a clinically applicable ADC barrier prediction model that can be implemented using multiplex immunofluorescence. Taken together, our findings reveal actionable spatial determinants of ADC efficacy and suggest potential combination therapeutic strategies.

Humans↗