Final analysis of the ALTTO trial: adjuvant trastuzumab in sequence or in combination with lapatinib in patients with HER2-positive early breast cancer [BIG 2-06/NCCTG N063D (Alliance)].

Background: Dual anti-human epidermal growth factor receptor 2 (HER2) blockade has improved the outcomes of patients with early and metastatic HER2-positive breast cancer. Here we present the final 10-year analysis of the ALTTO trial.

Patients And Methods: The ALTTO trial (NCT00490139) is a prospective randomized, phase III, open-label, multicenter study that investigated the role of adjuvant chemotherapy and trastuzumab alone, in combination or sequentially with lapatinib.

A pooled analysis of trastuzumab deruxtecan in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer with brain metastases.

Background: This exploratory pooled analysis investigated the efficacy and safety of trastuzumab deruxtecan (T-DXd) versus comparator treatment in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (mBC) with brain metastases (BMs) at baseline, categorized according to previous local treatment.

Patients And Methods: T-DXd data were pooled from DESTINY-Breast01/-02/-03. Comparator data, from patients receiving physician's choice therapy and trastuzumab emtansine, were pooled from DESTINY-Breast02 and -03, respectively.

Neratinib and ado-trastuzumab emtansine for pretreated and untreated human epidermal growth factor receptor 2 (HER2)-positive breast cancer brain metastases: Translational Breast Cancer Research Consortium trial 022.

Background: Treatment options for human epidermal growth factor receptor 2 (HER2)-positive breast cancer brain metastases (BCBMs) remain limited. We previously reported central nervous system (CNS) activity for neratinib and neratinib-capecitabine. Preclinical data suggest that neratinib may overcome resistance to ado-trastuzumab emtansine (T-DM1) when given in combination.

Adjuvant Trastuzumab Emtansine Versus Paclitaxel Plus Trastuzumab for Stage I Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer: 5-Year Results and Correlative Analyses From ATEMPT.

Purpose: Long-term outcomes of patients with stage I human epidermal growth factor receptor 2 (HER2)-positive breast cancer receiving adjuvant trastuzumab emtansine (T-DM1) remain undefined, and prognostic predictors represent an unmet need.

Methods: In the ATEMPT phase II trial, patients with stage I centrally confirmed HER2-positive breast cancer were randomly assigned 3:1 to adjuvant T-DM1 for 1 year or paclitaxel plus trastuzumab (TH). Coprimary objectives were to compare the incidence of clinically relevant toxicities between arms and to evaluate invasive disease-free survival (iDFS) with T-DM1.

Phase Ib dose-escalation trial of taselisib (GDC-0032) in combination with HER2-directed therapies in patients with advanced HER2+ breast cancer.

Background: In most patients with advanced human epidermal growth factor receptor-2-positive (HER2+) breast cancer, anti-HER2 therapies fail due to the development of acquired resistance, potentially mediated through phosphoinositide-3-kinase (PI3K) signaling. We investigated adding taselisib, an α-selective potent oral inhibitor of PI3K, to different HER2-directed regimens in order to improve disease control.

Patients And Methods: Patients (n = 68) with advanced HER2+ breast cancer were enrolled to this open-label, dose-escalation phase Ib study.

Trastuzumab deruxtecan versus treatment of physician's choice in patients with HER2-positive metastatic breast cancer (DESTINY-Breast02): patient-reported outcomes from a randomised, open-label, multicentre, phase 3 trial.

Background: In DESTINY-Breast02, patients with HER2-positive unresectable or metastatic breast cancer who received trastuzumab deruxtecan demonstrated superior progression-free and overall survival compared with those receiving treatment of physician's choice. We present the patient-reported outcomes (PROs) and hospitalisation data.

Methods: In this randomised, open-label, phase 3 trial conducted at 227 clinical sites globally, enrolled patients had to be aged 18 years or older with HER2-positive unresectable or metastatic breast cancer that had progressed on trastuzumab emtansine and had an Eastern Cooperative Oncology Group performance status of 0 or 1.

Clinical management, monitoring, and prophylaxis of adverse events of special interest associated with datopotamab deruxtecan.

Antibody drug conjugates (ADCs) are an emerging class of treatments designed to improve efficacy and decrease toxicity compared with other systemic therapies through the selective delivery of cytotoxic agents to tumor cells. Datopotamab deruxtecan (Dato-DXd) is a novel ADC comprising a topoisomerase I inhibitor payload and a monoclonal antibody directed to trophoblast cell-surface antigen 2 (TROP2), a protein that is broadly expressed in several types of solid tumors. Dato-DXd is being investigated across multiple solid tumor indications.

Analytical validation of HER2DX genomic test for early-stage HER2-positive breast cancer.

Background: HER2DX, a multianalyte genomic test, has been clinically validated to predict breast cancer recurrence risk (relapse risk score), the probability of achieving pathological complete response post-neoadjuvant therapy (pCR likelihood score), and individual ERBB2 messenger RNA (mRNA) expression levels in patients with early-stage human epidermal growth factor receptor 2 (HER2)-positive breast cancer. This study delves into the comprehensive analysis of HER2DX's analytical performance.

Materials And Methods: Precision and reproducibility of HER2DX risk, pCR, and ERBB2 mRNA scores were assessed within and between laboratories using formalin-fixed paraffin-embedded (FFPE) tumor tissues and purified RNA.

HER2 heterogeneity and treatment response-associated profiles in HER2-positive breast cancer in the NCT02326974 clinical trial.

BACKGROUNDHER2-targeting therapies have great efficacy in HER2-positive breast cancer, but resistance, in part due to HER2 heterogeneity (HET), is a significant clinical challenge. We previously described that in a phase II neoadjuvant trastuzumab emtansine (T-DM1) and pertuzumab (P) clinical trial in early-stage HER2-positive breast cancer, none of the patients with HER2-HET tumors had pathologic complete response (pCR).METHODSTo investigate cellular and molecular differences among tumors according to HER2 heterogeneity and pCR, we performed RNA sequencing and ERBB2 FISH of 285 pretreatment and posttreatment tumors from 129 patients in this T-DM1+P neoadjuvant trial.

TBCRC 039: a phase II study of preoperative ruxolitinib with or without paclitaxel for triple-negative inflammatory breast cancer.

Background: Patients with inflammatory breast cancer (IBC) have overall poor clinical outcomes, with triple-negative IBC (TN-IBC) being associated with the worst survival, warranting the investigation of novel therapies. Preclinical studies implied that ruxolitinib (RUX), a JAK1/2 inhibitor, may be an effective therapy for TN-IBC.

Methods: We conducted a randomized phase II study with nested window-of-opportunity in TN-IBC.

Prediction of Benefit From Adjuvant Pertuzumab by 80-Gene Signature in the APHINITY (BIG 4-11) Trial.

Purpose: At the primary analysis, the APHINITY trial reported a statistically significant but modest benefit of adding pertuzumab to standard adjuvant chemotherapy plus trastuzumab in patients with histologically confirmed human epidermal growth factor receptor 2 (HER2)-positive early-stage breast cancer. This study evaluated whether the 80-gene molecular subtyping signature (80-GS) could identify patients within the APHINITY population who derive the most benefit from dual anti-HER2 therapy.

Methods: In a nested case-control study design of 1,023 patients (matched event to control ratio of 3:1), the 80-GS classified breast tumors into functional luminal type, HER2 type, or basal type.

The HER2-directed antibody-drug conjugate DHES0815A in advanced and/or metastatic breast cancer: preclinical characterization and phase 1 trial results.

Approved antibody-drug conjugates (ADCs) for HER2-positive breast cancer include trastuzumab emtansine and trastuzumab deruxtecan. To develop a differentiated HER2 ADC, we chose an antibody that does not compete with trastuzumab or pertuzumab for binding, conjugated to a reduced potency PBD (pyrrolobenzodiazepine) dimer payload. PBDs are potent cytotoxic agents that alkylate and cross-link DNA.

Trastuzumab deruxtecan in previously treated patients with HER2-positive metastatic breast cancer: updated survival results from a phase II trial (DESTINY-Breast01).

Background: Primary analysis of the multicenter, open-label, single-arm, phase II DESTINY-Breast01 trial (median follow-up 11.1 months) demonstrated durable antitumor activity with trastuzumab deruxtecan (T-DXd) in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (mBC) previously treated with trastuzumab emtansine (T-DM1). We report updated cumulative survival outcomes with a median follow-up of 26.

Axillary Nodal Response to Neoadjuvant T-DM1 Combined with Pertuzumab in a Prospective Phase II Multi-Institution Clinical Trial.

Background: Patients with ERBB2 (HER2)-positive breast cancer experience high pathologic complete response (pCR) rates after standard neoadjuvant anti-HER2 systemic therapy. We examined axillary pathologic nodal response to neoadjuvant dual HER2-targeted therapy alone, based on breast pathologic response, in a multi-institution clinical trial.

Study Design: Patients with HER2-positive breast cancer were enrolled to a phase II single-arm trial, which administered 6 cycles of neoadjuvant trastuzumab emtansine (T-DM1) plus pertuzumab.

Immunological and clinicopathological features predict HER2-positive breast cancer prognosis in the neoadjuvant NeoALTTO and CALGB 40601 randomized trials.

The identification of prognostic markers in patients receiving neoadjuvant therapy is crucial for treatment optimization in HER2-positive breast cancer, with the immune microenvironment being a key factor. Here, we investigate the complexity of B and T cell receptor (BCR and TCR) repertoires in the context of two phase III trials, NeoALTTO and CALGB 40601, evaluating neoadjuvant paclitaxel with trastuzumab and/or lapatinib in women with HER2-positive breast cancer. BCR features, particularly the number of reads and clones, evenness and Gini index, are heterogeneous according to hormone receptor status and PAM50 subtypes.

Patritumab Deruxtecan (HER3-DXd), a Human Epidermal Growth Factor Receptor 3-Directed Antibody-Drug Conjugate, in Patients With Previously Treated Human Epidermal Growth Factor Receptor 3-Expressing Metastatic Breast Cancer: A Multicenter, Phase I/II Trial.

Purpose: Human epidermal growth factor receptor 3 (HER3) is broadly expressed in breast cancer; high expression is associated with an adverse prognosis. Patritumab deruxtecan (HER3-DXd) is an investigational HER3-targeted antibody-drug conjugate that is being evaluated as a novel treatment in HER3-expressing advanced breast cancer in the U31402-A-J101 study.

Methods: Adults with disease progression on previous therapies were eligible.

Circulating tumor DNA association with residual cancer burden after neoadjuvant chemotherapy in triple-negative breast cancer in TBCRC 030.

Background: We aimed to examine circulating tumor DNA (ctDNA) and its association with residual cancer burden (RCB) using an ultrasensitive assay in patients with triple-negative breast cancer (TNBC) receiving neoadjuvant chemotherapy.

Patients And Methods: We identified responders (RCB 0/1) and matched non-responders (RCB 2/3) from the phase II TBCRC 030 prospective study of neoadjuvant paclitaxel versus cisplatin in TNBC. We collected plasma samples at baseline, 3 weeks and 12 weeks (end of therapy).

Genomics of -Positive Breast Cancer in Young Women Before and After Exposure to Chemotherapy Plus Trastuzumab.

Purpose: Erb-B2 receptor tyrosine kinase 2 ()-positive breast cancer (BC) is particularly common in young women. Genomic features of -positive tumors before and after chemotherapy and trastuzumab (chemo + H) have not been described in young women and are important for guiding study of therapeutic resistance in this population.

Methods: From a large prospective cohort of women age 40 years or younger with BC, we identified patients with -positive BC and tumor tissue available before and after chemo + H.

A Multiparameter Molecular Classifier to Predict Response to Neoadjuvant Lapatinib plus Trastuzumab without Chemotherapy in HER2+ Breast Cancer.

Purpose: Clinical trials reported 25% to 30% pathologic complete response (pCR) rates in HER2+ patients with breast cancer treated with anti-HER2 therapies without chemotherapy. We hypothesize that a multiparameter classifier can identify patients with HER2-"addicted" tumors who may benefit from a chemotherapy-sparing strategy.

Experimental Design: Baseline HER2+ breast cancer specimens from the TBCRC023 and PAMELA trials, which included neoadjuvant treatment with lapatinib and trastuzumab, were used.