Approximately 20% of breast cancers are characterized by overexpression of human epidermal growth factor receptor 2 (HER2) protein and associated gene amplification, and the receptor tyrosine kinase ...is believed to play a critical role in the pathogenesis of these tumors. The development and implementation of trastuzumab, a humanized monoclonal antibody against the extracellular domain of HER2 protein, has significantly improved treatment outcomes in patients with HER2‐overexpressing breast cancer. However, despite this clinical usefulness, unmet needs for better prediction of trastuzumab’s response and overcoming primary and acquired resistance remain. In this review, we discuss several potential mechanisms of resistance to trastuzumab that have been closely studied over the last decade. Briefly, these mechanisms include: impaired access of trastuzumab to HER2 by expression of extracellular domain‐truncated HER2 (p95 HER2) or overexpression of MUC4; alternative signaling from insulin‐like growth factor‐1 receptor, other epidermal growth factor receptor family members, or MET; aberrant downstream signaling caused by loss of phosphatase and tensin homologs deleted from chromosome 10 (PTEN), PIK3CA mutation, or downregulation of p27; or FCGR3A polymorphisms. In addition, we discuss potential strategies for overcoming resistance to trastuzumab. Specifically, the epidermal growth factor receptor/HER2 tyrosine kinase inhibitor lapatinib partially overcame trastuzumab resistance in a clinical setting, so its efficacy results and limited data regarding potential mechanisms of resistance to the drug are also discussed. (Cancer Sci 2011; 102: 1–8)
Amplification and/or overexpression of human epidermal growth factor receptor 2 (HER2) are observed in 15-20% of breast cancers (HER2+ breast cancers), and anti-HER2 therapies have significantly ...improved prognosis of patients with HER2+ breast cancer. One resistance mechanism to anti-HER2 therapies is constitutive activation of the phosphoinositide 3-kinase (PI3K) pathway. Combination therapy with small-molecule inhibitors of AKT and HER2 was conducted in HER2+ breast cancer cell lines with or without PIK3CA mutations, which lead to constitutive activation of the PI3K pathway. PIK3CA mutations played important roles in resistance to single-agent anti-HER2 therapy in breast cancer cell lines. Combination therapy of a HER2 inhibitor and an AKT inhibitor, as well as other PI3K pathway inhibitors, could overcome the therapeutic limitations associated with single-agent anti-HER2 treatment in PIK3CA-mutant HER2+ breast cancer cell lines. Furthermore, expression of phosphorylated 4E-binding protein 1 (p4EBP1) following the treatment correlated with the antiproliferative activities of the combination, suggesting that p4EBP1 may have potential as a prognostic and/or efficacy-linking biomarkers for these combination therapies in patients with HER2+ breast cancer. These findings highlight potential clinical strategies using combination therapy to overcome the limitations associated with single-agent anti-HER2 therapies in patients with HER2+ breast cancer.
It is becoming recognized that screening of oncology drugs on a platform using two-dimensionally (2D)-cultured cell lines is unable to precisely select clinically active drugs; therefore ...three-dimensional (3D)-culture systems are emerging and show potential for better simulating the in vivo tumor microenvironment. The purpose of this study was to reveal the differential effects of chemotherapeutic drugs between 2D- and 3D-cultures and to explore their underlying mechanisms. We evaluated differences between 2D- and 3D-cultured breast cancer cell lines by assessing drug sensitivity, oxygen status and expression of Ki-67 and caspases. Three cell lines (BT-549, BT-474 and T-47D) developed dense multicellular spheroids (MCSs) in 3D-culture, and showed greater resistance to paclitaxel and doxorubicin compared to the 2D-cultured cells. An additional three cell lines (MCF-7, HCC-1954, and MDA-MB‑231) developed only loose MCSs in 3D, and showed drug sensitivities similar to those found in the 2D-culture. Treatment with paclitaxel resulted in greater increases in cleaved-PARP expression in the 2D-culture compared with the 3D-culture, but only in cell lines forming dense 3D-MCSs, suggesting that MCS formation protected the cells from paclitaxel-induced apoptosis. Hypoxia was observed only in the dense 3D-MCSs. BT-549 had fewer cells positive for Ki-67 in 3D- than in 2D-culture, suggesting that the greater G0-dormant subpopulation was responsible for its drug resistance in the 3D-culture. BT-474 had a lower level of caspase-3 in the 3D- than in the 2D-culture, suggesting that the 3D-environment was anti-apoptotic. Finally, we compared staining for Ki-67 and caspases in the 2D- and 3D-primary‑cultured cells originating from a patient-derived xenograft (PDX), fresh PDX tumor, and the patient's original tumor; 2D-cultured cells showed greater proportions of Ki-67-positive and caspase-3-positive cells, in agreement with the view that 3D-primary culture better represents characteristics of tumors in vivo. In conclusion, 3D-cultured cells forming dense MCSs may be better than 2D-cultured cells in simulating important tumor characteristics in vivo, namely hypoxia, dormancy, anti-apoptotic features and their resulting drug resistance.
Background and Purpose
Intratumour heterogeneity frequently leads to drug resistance, which is a major issue in drug discovery. Drug distribution is one of the key factors for elucidating the ...resistance mechanism; however, quantitative and regional drug measurement is challenging. Here, we developed a novel ultra‐sensitive analytical method and applied it to HER3‐targeting antibody–drug conjugate patritumab deruxtecan (HER3‐DXd), aiming to explore its payload (DXd) distribution within heterogeneous tissues.
Experimental Approach
The developed analytical method is named LDMS‐CE‐MS, a capillary electrophoresis‐mass spectrometry (CE‐MS) coupled with a novel sample preconcentration/separation method called “large‐volume dual‐sample stacking by micelle collapse and sweeping (LDMS)”. First, the analytical performance of LDMS‐CE‐MS for DXd detection was evaluated. Subsequently, we evaluated the bystander effect of HER3‐DXd, where tumour tissues were excised from xenograft models and clinical specimens after administration of HER3‐DXd. HER3‐high expression, adjacent, and HER3‐low expression regions were then sampled by laser microdissection to quantify the released DXd.
Key Results
LDMS concentrated DXd by 1000‐fold and separated it from the hydrophilic bio‐matrix through continuous capture and release by the charged micelles, allowing quantification at sub‐attomole‐level. DXd concentrations decreased in the order of antigen‐high expression > adjacent > antigen‐low expression regions in the tumour xenograft model, whereas in clinical specimens, adjacent and antigen‐high expression regions had approximately the same concentration. These distributions represent a bystander effect.
Conclusions and Implications
Our LDMS‐CE‐MS successfully visualized the attomole‐level drug distributions in heterogeneous clinical specimens. This new platform opens a new era of quantitative pharmacokinetic analysis, facilitating drug discovery and development.
The area of residual tumor (ART) is a prognostic factor in patients treated with neoadjuvant chemotherapy (NAC) for lung, pancreatic, and rectal cancers. This study aimed to evaluate the usefulness ...of ART as a method for predicting the prognosis of triple‐negative breast cancer (TNBC) patients after NAC. We included 143 patients with TNBC treated with NAC. The ART at the maximum cut surface of the residual tumor was measured. We divided the patients into three groups: ART‐0 (ART = 0 mm2), ART‐low (0 mm2 < ART ≤ 136mm2), and ART‐high (ART > 136 mm2), and compared their clinicopathologic factors and prognosis. There were no significant differences in either recurrence‐free survival (RFS) or overall survival (OS) between ART‐0 and ART‐low; however, the ART‐high group had significantly shorter RFS and OS than the ART‐0 and ART‐low groups. Multivariate analysis showed that ART‐0 and ‐low and ypN(−) were independent favorable prognostic factors for RFS. Groups with both ART‐low and ypN(−) as well as those with ART‐0 and ypN(−) showed significantly longer OS and RFS than the other groups (P < .05). Moreover, there was no significant difference in the RFS and OS between the ART‐0 and ypN(−) groups and the ART‐low and ypN(−) groups (P = .249 and P = .554, respectively). We concluded that ART is a candidate histopathological evaluation method for predicting the prognosis of TNBC patients treated with NAC. Furthermore, postoperative chemotherapy could be omitted in patients with ART‐0 and ypN(−) (pathological complete response) and those with ART‐low and ypN(−).
This study aimed to evaluate the usefulness of area of residual tumor (ART) as a method for predicting the prognosis of patients with triple‐negative breast cancer (TNBC) after neoadjuvant chemotherapy (NAC). Based on the results of this study, patients with ART‐low have a good prognosis, as well as those with pathological complete response. ART‐low patients are good candidates for histopathological evaluation to predict the prognosis of TNBC patients who received NAC, and could be used to select candidates for omission of capecitabine.
Preclinical models revealed potential synergistic effects of programmed cell death-1 inhibitors and anti-vascular endothelial growth factor (VEGF) antibodies. Therefore, we investigated the use of ...nivolumab, bevacizumab, and paclitaxel triple therapy for metastatic breast cancer.
This phase 2, multicentre, single-arm study (NEWBEAT) investigated the safety and efficacy of first-line nivolumab, paclitaxel, and bevacizumab in patients with human epidermal growth factor receptor 2-negative metastatic breast cancer, regardless of programmed cell death-ligand 1 expression. The primary end-point was objective response rate. Key secondary end-points included progression-free survival, overall survival, and toxicities. A biomarker study evaluated tumour programmed cell death-ligand 1 expression and serum VEGF-A levels.
Between February 2018 and October 2018, 57 patients were enrolled. An objective response rate was seen in 39/56 patients (70%, 95% confidence interval CI: 55.9–81.2%), meeting the primary end-point. The objective response rate was 74% in patients with hormone receptor-positive breast cancer versus 59% in patients with triple-negative breast cancer. The median progression-free survival and overall survival were 14.0 (95% CI 11.0–16.3) and 32.5 (95% CI 26.0–not evaluable) months, respectively (median follow-up: 29.5 months). Grade 3/4 adverse drug reactions occurred in 33 of 57 patients (58%). There were no grade 5 adverse events. Immune-related adverse events occurred in 43 of 57 patients (75%), with grade 3/4 events in eight patients (14%). Biomarker analysis showed that tumour programmed cell death-ligand 1 expression was not correlated with the efficacy of triple therapy. Efficacy outcomes were similar between the serum VEGF-high and VEGF-low groups.
First-line nivolumab, bevacizumab, and paclitaxel therapy showed promising efficacy and manageable toxicity in patients with human epidermal growth factor receptor 2-negative metastatic breast cancer.
•First clinical trial to report efficacy of nivolumab, bevacizumab, and paclitaxel.•Objective response rates were promising (74% in HR+HER2− and 59% in patients with triple-negative breast cancer).•The median progression-free survival and overall survival were 14.0 months and 32.5 months, respectively.•Tumour programmed cell death-ligand 1 expression was not correlated with the efficacy of triple therapy.•Efficacy and prognosis were similar between serum vascular endothelial growth factor-high and vascular endothelial growth factor-low groups.
Drug selection and treatment monitoring
minimally invasive liquid biopsy using circulating tumor cells (CTCs) are expected to be realized in the near future. For clinical applications of CTCs, ...simple, high-throughput, single-step CTC isolation from whole blood without red blood cell (RBC) lysis and centrifugation remains a crucial challenge. In this study, we developed a novel cancer cell separation chip, "hybrid double-spiral chip", that involves the serial combination of two different Dean flow fractionation (DFF) separation modes of half and full Dean cycles, which is the hybrid DFF separation mode for ultra-high-throughput blood processing at high precision and size-resolution separation. The chip allows fast processing of 5 mL whole blood within 30 min without RBC lysis and centrifugation. RBC and white blood cell (WBC) depletion rates of over 99.9% and 99%, respectively, were achieved. The average recovery rate of spiked A549 cancer cells was 87% with as low as 200 cells in 5 mL blood. The device can achieve serial reduction in the number of cells from approximately 10
cells of whole blood to 10
cells, and subsequently to an order of 10
cells. The developed method can be combined with measurements of all recovered cells using imaging flow cytometry. As proof of concept, CTCs were successfully enriched and enumerated from the blood of metastatic breast cancer patients (
= 10, 1-69 CTCs per 5 mL) and metastatic prostate cancer patients (
= 10, 1-39 CTCs per 5 mL). We believe that the developed method will be beneficial for automated clinical analysis of rare CTCs from whole blood.
Axitinib is an oral, potent, and selective inhibitor of vascular endothelial growth factor receptor (VEGFR) 1, 2, and 3. This phase I study evaluated the safety, pharmacokinetics, pharmacodynamics, ...antitumor activity, and recommended starting dose of axitinib in patients with advanced solid tumors. Twelve patients received single‐dose axitinib 5 mg and were monitored for ≥48 h. Continuous 5 mg twice‐daily dosing was then initiated. One patient had dose‐limiting toxicity (grade 3 proteinuria and fatigue). Common treatment‐related adverse events were anorexia, fatigue, and diarrhea. Grade 3 treatment‐related adverse events were fatigue and hypertension. Maximum axitinib plasma concentration occurred 1–4 h after steady‐state dosing. Eleven patients experienced thyroid‐stimulating hormone elevation; time‐course change and fatigue onset appeared to be related in some patients. Significant correlation was observed between thyroid‐stimulating hormone change and area under the plasma concentration–time curve (AUC; r = 0.80, P = 0.005). Axitinib decreased plasma soluble vascular endothelial growth factor receptor 2 (s‐VEGFR2), with significant correlation between change in s‐VEGFR2 and AUC (r = −0.92, P < 0.0001). Fluorodeoxyglucose positron emission tomography revealed a substantial decrease in tumor metabolic activity associated with axitinib. Tumor size decreased in nine patients. The time‐course of thyroid‐stimulating hormone change appeared correlated with fatigue. There were significant correlations between thyroid‐stimulating hormone or s‐VEGFR2 and axitinib exposure. Axitinib 5 mg twice‐daily is the recommended starting dose for Japanese patients. This trial is registered with ClinicalTrials.gov, identifier NCT00447005. (Cancer Sci 2010)
(Cancer Sci 2010; 101: 963–968)
Somatic mutations in human epidermal growth factor receptor 2 (HER2) are present in approximately 3% of breast cancers. Some HER2 mutations are activating, and they represent a mechanism of ...resistance to conventional anti‐HER2 therapies such as trastuzumab and lapatinib. Consistently, in patients with HER2‐amplified breast cancer, these mutations are predominantly observed in metastatic tumors obtained after exposure to anti‐HER2 systemic therapies, possibly after clonal selection. Therefore, it is rare to find coexistent HER2 mutation and amplification in the early clinical course, and thus, the clinical relevance of HER2 mutation to the sensitivity to HER2‐targeted drugs, particularly antibody‐drug conjugates (ADCs) such as ado‐trastuzumab emtansine (T‐DM1) and the recently approved fam‐trastuzumab deruxtecan (T‐DXd), remains unclear. In this article, we describe a patient with de novo metastatic breast cancer who exhibited both HER2 amplification and the L755S mutation in the untreated primary breast tumor obtained at the initial diagnosis, and the lesion responded to T‐DM1 and T‐DXd after exhibiting clinical resistance to other HER2‐targeted drugs. Our current case findings suggested that anti‐HER2 ADCs should be prioritized over conventional trastuzumab‐ or lapatinib‐based therapies for patients with HER2‐amplified and comutated tumors.
Key Points
Although HER2 mutations were implicated in resistance to anti‐HER2 monoclonal antibodies or HER2 tyrosine kinase inhibitors in preclinical studies, their clinical impact on sensitivity to anti‐HER2 drugs is unclear owing to the rarity of concomitant HER2 mutation and HER2 amplification.
A case of de novo metastatic breast cancer harboring both HER2 amplification and the L755S mutation in an untreated breast primary tumor displayed clinical resistance to standard trastuzumab‐ or lapatinib‐based therapies but good responses to ado‐trastuzumab emtansine (T‐DM1) and fam‐trastuzumab deruxtecan (T‐DXd).
Anti‐HER2 antibody‐drug conjugates such as T‐DM1 and T‐DXd may be prioritized over conventional trastuzumab‐ or lapatinib‐containing therapies for patients with HER2‐amplified and comutated tumors.
This article reports the case of a patient with de novo metastatic breast cancer who harbored both HER2 amplification and the L755S mutation in the untreated primary breast tumor obtained at the initial diagnosis, detailing her response to treatment with HER2‐targeted drugs.
A liposomal formulation of eribulin, E7389-LF, may provide improved pharmacokinetics and allow increased access to tumour tissues. This expansion of a phase 1 study assessed the safety and efficacy ...of E7389-LF in patients with human epidermal growth factor receptor type 2-negative metastatic breast cancer.
Patients received E7389-LF 2.0 mg/m2 every three weeks. Tumour assessments were conducted every six weeks by the investigator by Response Evaluation Criteria in Solid Tumours v1.1. All adverse events were monitored and recorded. Serum biomarker assessments were conducted.
Of 28 patients included, 75.0% had hormone receptor-positive breast cancer (HR+ BC) and 25.0% had triple-negative breast cancer (TNBC). The most common grade ≥3 treatment-related treatment-emergent adverse events included neutropenia (67.9%), leukopenia (42.9%), thrombocytopenia (32.1%), and febrile neutropenia (25.0%). Rates of neutropenia and febrile neutropenia were lower among patients who received prophylactic pegfilgrastim. Objective response rate was 35.7% (95% confidence interval CI: 18.6–55.9) for all patients and 42.9% (95% CI: 21.8–66.0) for patients with HR+ BC. Median progression-free survival was 5.7 months (95% CI: 3.9–8.3). The median overall survival was 18.3 months (95% CI: 13.2–not estimable). Among the 54 biomarkers assessed, 27, including 5 of 7 vascular markers, were significantly altered by E7389-LF treatment from baseline to any time point.
E7389-LF was tolerable and favourable antitumour activity was observed, particularly in patients with HR+ BC. Prophylactic pegfilgrastim can be considered in patients at high risk for neutropenia and febrile neutropenia.
NCT03207672.
•Liposomal eribulin, E7389-LF, has promising efficacy in patients with breast cancer.•Neutropenia and febrile neutropenia were common adverse events.•Prophylactic pegfilgrastim lowered incidence of neutropenia and febrile neutropenia.•Vascular-related biomarkers changed from baseline over time.
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