Low PTEN levels and <Emphasis Type="Italic">PIK3CA</Emphasis> mutations predict resistance to neoadjuvant lapatinib and trastuzumab without chemotherapy in patients with HER2 over-expressing breast cancer

Purpose

Aberrant activation of the PI3K pathway has been implicated in resistance to HER2-targeted therapy, but results of clinical trials are confounded by the co-administration of chemotherapy. We investigated the effect of perturbations of this pathway in breast cancers from patients treated with neoadjuvant anti-HER2-targeted therapy without chemotherapy.

Patients and methods

Baseline tumor samples from patients with HER2-positive breast cancer enrolled in TBCRC006 (NCT00548184), a 12-week neoadjuvant clinical trial with lapatinib plus trastuzumab [plus endocrine therapy for estrogen receptor (ER)-positive tumors], were assessed for PTEN status by immunohistochemistry and PIK3CA mutations by sequencing. Results were correlated with pathologic complete response (pCR).

Results

Of 64 evaluable patients, PTEN immunohistochemistry and PIK3CA mutation analysis were performed for 59 and 46 patients, respectively. PTEN status (dichotomized by H-score median) was correlated with pCR (32% in high PTEN vs. 9% in low PTEN, p = 0.04). PIK3CA mutations were identified in 14/46 tumors at baseline (30%) and did not correlate with ER or PTEN status. One patient whose tumor harbored a PIK3CA mutation achieved pCR (p = 0.14). When considered together (43 cases), 1/25 cases (4%) with a PIK3CA mutation and/or low PTEN expression levels had a pCR compared to 7/18 cases (39%) with wild-type PI3KCA and high PTEN expression levels (p = 0.006).

Conclusion

PI3K pathway activation is associated with resistance to lapatinib and trastuzumab in breast cancers, without chemotherapy. Further studies are warranted to investigate how to use these biomarkers to identify upfront patients who may respond to anti-HER2 alone, without chemotherapy.

     

Incidence,Diagnosis, and Treatment of Cardiac Toxicity From Trastuzumab in Patients With Breast Cancer

Purpose of Review

Treatment with trastuzumab is a cornerstone of human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer treatment, but carries an unfortunate risk of toxicity to the cardiovascular system. Here, we review recent findings on trastuzumab-associated cardiotoxicity, focusing on its incidence, diagnosis, and treatment.

Recent Findings

Screening with multigated acquisition scan (MUGA) or echocardiogram (ECHO) is recommended to assess cardiac function prior to and during trastuzumab therapy. Because trastuzumab-induced cardiotoxicity is typically reversible, cessation of trastuzumab and/or administration of first-line heart failure agents effectively restores cardiac function in most cases. Severe trastuzumab-induced cardiotoxicity is rare enough that the risk-benefit ratio still weighs in favor of its use in the vast majority of patients with HER2+ breast cancer.

Summary

An improved understanding of the pathophysiology underlying trastuzumab-induced cardiotoxicity and the identification of patients at highest risk will allow us to continue to safely administer trastuzumab in patients with breast cancer.

     

A83-01 inhibits TGF-β-induced upregulation of Wnt3 and epithelial to mesenchymal transition in HER2-overexpressing breast cancer cells

Purpose

The aim of this study is to investigate the mechanisms of interactions between TGF-β and Wnt/β-catenin pathways that induce and regulate EMT and promote breast cancer cells to become resistant to treatment.

Methods

The effect of TGF-β on Wnt/β-catenin signaling pathway was examined by using a human Wnt/β-catenin-regulated cDNA plate array and western blot analysis. The interaction of Twist at promoter of Wnt3 was examined by chromatin immunoprecipitation (ChIP) assay. Secreted Wnt3 level was determined by ELISA assay.

Results

HER2-overexpressing breast cancer cells treated with TGF-β have a reduced response to trastuzumab and exhibited EMT-like phenotype. The TGF-β-induced EMT in HER2-cells was concordant with upregulation of Wnt3 and β-catenin pathways. The TGF-β-induced induction of Wnt3 during EMT was found to be Smad3-dependent. ChIP analysis identified occupancy of Twist at promoter region of Wnt3. Knock-down of Twist by shRNA confirmed the significance of Twist in response to TGF-β regulating Wnt3 during EMT. Subsequently, TGF-β-induced matrix metalloproteinases, MMP1, MMP7, MMP9, MMP26, Vascular endothelial growth factors (VEGF), and activation of Wnt/β-catenin signaling were repressed by the shRNA treatment. TGF-βR1 ALK5 kinase inhibitor, A83-01 can effectively prevent the TGF-β-induced Twist and Wnt3. Co-treating A83-01 and trastuzumab inhibited TGF-β-induced cell invasion significantly in both trastuzumab responsive and resistant cells.

Conclusions

Our data demonstrated an important interdependence between TGF-β and Wnt/β-catenin pathways inducing EMT in HER2-overexpressing breast cancer cells. Twist served as a linkage between the two pathways during TGF-β-induced EMT. A83-01 could inhibit the TGF-β-initiated pathway interactions and enhance HER2-cells response to trastuzumab treatment.

     

Effects of trastuzumab on locoregional recurrence in human epidermal growth factor receptor 2-overexpressing breast cancer patients treated with chemotherapy and radiotherapy

Purpose

In the present study, the ability of adjuvant trastuzumab to reduce locoregional recurrence in patients with human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer receiving adjuvant chemotherapy and radiotherapy (RT) was investigated.

Materials and methods

We retrospectively included 520 patients with HER2-overexpressing breast cancer who received surgery followed by adjuvant RT and cytotoxic chemotherapy from 2003 to 2011. Adjuvant trastuzumab was administered to 286 patients. Propensity score matching was conducted to compare trastuzumab-treated and non-treated cohorts.

Results

Median follow-up duration was 7.1 years (range 1.1–14.1 years). Propensity score matching yielded 171 matched pairs of patients with no significantly different clinical factors. An improved 7-year locoregional control (LRC) rate was observed in the trastuzumab-treated cohort compared with the non-treated cohort (95.6% vs. 89.9%, p?=?0.014). Based on multivariate analysis, hormone receptor negativity (hazard ratio [HR]?=?5.348, p?=?0.007), positive lymph node ratio?>?0.25 (HR?=?2.549, p?=?0.040), and lack of adjuvant trastuzumab (HR?=?3.401, p?=?0.017) were identified as significant risk factors for poor LRC. Adjuvant trastuzumab significantly reduced the locoregional recurrence rate in patients with one or two risk factors (7-year LRC?=?95.0% vs. 84.2%, p?=?0.007); however, the benefit of adjuvant trastuzumab was non-significant in patients with no risk factors (7-year LRC?=?95.8% vs. 97.9%, p?=?0.75).

Conclusions

Adjuvant trastuzumab improved LRC in patients with HER2-overexpressing breast cancer receiving adjuvant RT and cytotoxic chemotherapy, especially in hormone receptor-negative, HER2-enriched subtype, and high positive lymph node ratio breast cancer.

     

<Emphasis Type="Italic">PIK3CA</Emphasis> mutations and <Emphasis Type="Italic">TP53</Emphasis> alterations cooperate to increase cancerous phenotypes and tumor heterogeneity

Background/purpose

The combined contributions of oncogenes and tumor suppressor genes toward carcinogenesis remain poorly understood. Elucidation of cancer gene cooperativity can provide new insights leading to more effective use of therapies.

Experimental design/Methods

We used somatic cell genome editing to introduce singly and in combination PIK3CA mutations (E545K or H1047R) with TP53 alterations (R248W or knockout), to assess any enhanced cancerous phenotypes. The non-tumorigenic human breast epithelial cell line, MCF10A, was used as the parental cell line, and resultant cells were assessed via various in vitro assays, growth as xenografts, and drug sensitivity assays using targeted agents and chemotherapies.

Results

Compared to single-gene-targeted cells and parental controls, cells with both a PIK3CA mutation and TP53 alteration had increased cancerous phenotypes including cell proliferation, soft agar colony formation, aberrant morphology in acinar formation assays, and genomic heterogeneity. Cells also displayed varying sensitivities to anti-neoplastic drugs, although all cells with PIK3CA mutations showed a relative increased sensitivity to paclitaxel. All cell lines remained non-tumorigenic.

Conclusions

This cell line panel provides a resource for further elucidating cooperative genetic mediators of carcinogenesis and response to therapies.

     

Fc-Gamma receptor polymorphism and gene expression of peripheral blood mononuclear cells in patients with HER2-positive metastatic breast cancer receiving single-agent trastuzumab

Aim

The aim of this study was to investigate gene expression in the peripheral blood mononuclear cells (PBMCs) of patients with HER2-positive breast cancer receiving trastuzumab. We also evaluated the effect of Fc-gamma receptor genotype on trastuzumab-driven gene expression.

Materials and methods

Gene expression was assessed by microarray analyses before and after administration of single-agent trastuzumab in 34 patients with metastatic HER2-positive breast cancer who were genotyped for Fc-gamma receptor (FcGR) IIA H131R and FcGRIIIA V158F. Gene set enrichment analysis (GSEA) was used to identify the gene sets that were significantly enriched after administration of trastuzumab in patient cohorts categorized by FcGR variant.

Results

At baseline three non-immune-related gene sets were identified only in patient cohort of FcGRIIA non-H/H variant. Thirty gene sets were identified in the cohort of FcGRIIIA V/V variants, while no gene set was identified in FcGRIIIA non-V/V variants one week after starting trastuzumab. Eleven gene sets were identified in FcGRIIA H/H variants 8 week after starting trastuzumab, but none in non-H/H variants. Immune-related gene sets were significantly down-regulated after administration of trastuzumab.

Conclusion

The response of PBMCs to trastuzumab markedly varied with polymorphisms in FcGRIIA and FcGRIIIA. These results indicate that FcGR polymorphisms contribute to the systemic immune reaction triggered by trastuzumab. Further investigations are needed to clarify the biological effects of FcGR variation on the mechanism of trastuzumab activity.

     

A portrait of germline mutation in Brazilian at-risk for hereditary breast cancer

Purpose

HER2?+?breast cancer (BC) is an aggressive subtype with high rates of brain metastases (BCBM). Two-thirds of HER2?+?BCBM demonstrate activation of the PI3K/mTOR pathway driving resistance to anti-HER2 therapy. This phase II study evaluated everolimus (E), a brain-permeable mTOR inhibitor, trastuzumab (T), and vinorelbine (V) in patients with HER2?+?BCBM.

Patients and methods

Eligible patients had progressive HER2?+?BCBM. The primary endpoint was intracranial response rate (RR); secondary objectives were CNS clinical benefit rate (CBR), extracranial RR, time to progression (TTP), overall survival (OS), and targeted sequencing of tumors from enrolled patients. A two-stage design distinguished intracranial RR of 5% versus 20%.

Results

32 patients were evaluable for toxicity, 26 for efficacy. Intracranial RR was 4% (1 PR). CNS CBR at 6 mos was 27%; at 3 mos 65%. Median intracranial TTP was 3.9 mos (95% CI 2.2–5). OS was 12.2 mos (95% CI 0.6–20.2). Grade 3–4 toxicities included neutropenia (41%), anemia (16%), and stomatitis (16%). Mutations in TP53 and PIK3CA were common in BCBM. Mutations in the PI3K/mTOR pathway were not associated with response. ERBB2 amplification was higher in BCBM compared to primary BC; ERBB2 amplification in the primary BC trended toward worse OS.

Conclusion

While intracranial RR to ETV was low in HER2?+?BCBM patients, one-third achieved CNS CBR; TTP/OS was similar to historical control. No new toxicity signals were observed. Further analysis of the genomic underpinnings of BCBM to identify tractable prognostic and/or predictive biomarkers is warranted. Clinical Trial: (NCT01305941).

     

Multicenter phase II study of trastuzumab plus S-1 alone in elderly patients with HER2-positive advanced gastric cancer (JACCRO GC-06)

Background

S-1 plus cisplatin is a standard regimen for advanced gastric cancer (AGC) in Asia. The ToGA trial established a fluoropyrimidine plus cisplatin and trastuzumab as a standard treatment for human epidermal growth factor receptor 2 (HER2)-positive AGC. In the HERBIS-1 trial, trastuzumab combined with S-1 plus cisplatin showed promising antitumor activity in patients with HER2-positive AGC. However, cisplatin has several important drawbacks, including vomiting and renal toxicity. These disadvantages of cisplatin are prominent in elderly patients. Therefore, we conducted a prospective phase II study of trastuzumab plus S-1 without cisplatin in elderly patients with HER2-positive AGC.

Methods

Patients 65 years or older who had HER2-positive AGC received S-1 orally on days 1–28 of a 42-day cycle and trastuzumab intravenously on day 1 of a 21-day cycle.

Results

A total of 51 patients were enrolled. Two patients were ineligible. The full analysis set thus comprised 49 patients. The median age was 71 years (range 65–85). The confirmed response rate was 40.8% (95% CI 27.1–54.6%), and the null hypothesis was rejected. The median follow-up period was 10.6 months. Median overall survival was 15.8 months. Median progression-free survival was 5.1 months, and time to treatment failure was 4.0 months. Major grade 3 or 4 adverse events included neutropenia (12.0%), anemia (24.0%), diarrhea (10.0%), and anorexia (12.0%). There was one treatment-related death.

Conclusions

Trastuzumab in combination with S-1 alone demonstrated promising antitumor activity and manageable toxic effects as well as promising survival results in elderly patients with HER2-positive AGC.

Clinical trials registration

UMIN000007368.

     

Predictive factors of trastuzumab-based chemotherapy in HER2 positive advanced gastric cancer: a single-center prospective observational study

Purpose

Trastuzumab plus chemotherapy is an effective therapy in HER2 positive advanced gastric cancer (AGC). However, the clinicopathologic factors that predict the outcome of routine trastuzumab therapy remain unclear.

Methods

The outcome and safety profile of trastuzumab therapy in untreated HER2 positive AGC was evaluated in this prospective observational study. Clinical and pathological data including demographics, treatment profiles, expression level of HER2 were analyzed to identify predictive factors of trastuzumab-based first-line therapy for their progression-free survival (PFS).

Results

Overall, 107 patients were eligible. The median number of treatment cycles was 9 (range 1–44), the median PFS and median overall survival (OS) were 7.7 months (95% CI 6.5–8.9) and 16.0 months (95% CI 13.2–18.8), respectively. The confirmed response rate was 58.9%, and the disease control rate was 82.2%. Patients with liver metastasis (HR 1.616) and poor performance status (PS, HR 2.518) were independently associated with a worse PFS, while the other clinicopathological factors including demographics, treatment profiles and some other clinical characteristics did not predict the survival.

Conclusions

In routine clinical practice, the addition of trastuzumab to chemotherapy was effective and safe in real-world setting in Chinese patients with HER2 positive AGC, regardless of most of the clinicopathological factors. Further studies are needed to improve the prognosis of HER2 positive patients with liver metastasis or poor PS. Trial Registration clinicaltrials.gov Identifier: NCT03024450

     

The yield of full <Emphasis Type="Italic">BRCA1</Emphasis>/<Emphasis Type="Italic">2</Emphasis> genotyping in Israeli high-risk breast/ovarian cancer patients who do not carry the predominant mutations

Purpose

Patients treated with trastuzumab for HER2-positive metastatic breast cancer (HER2+MBC) are living longer, but there is little information on their outcomes and treatment experience beyond the median survival from clinical trials and real-world observational studies. We aim to describe the real-world treatment patterns and overall survival (OS) for women surviving five or more years from initiation of trastuzumab for HER2+MBC.

Methods

This is a retrospective, whole-of-population cohort study of women initiating trastuzumab for HER2+MBC between 2001 and 2011, followed to 2016. We defined long-term survivors (LTS) as those patients surviving?≥?5 years from trastuzumab initiation. We used dispensing claims to describe timing of cancer treatments used by LTS and to estimate time on and off HER2-targeted therapies, and OS from trastuzumab initiation for HER2+MBC.

Results

Of 4177 women initiating trastuzumab for HER2+MBC, 1082 (26%) survived ≥?5 years. Median age for LTS was 54 years (IQR 46–63). At a median follow-up of 9.4 years, 36% of LTS died; their conditional probability of surviving an additional 5 years was 55%. Median time on trastuzumab and all HER2-targeted therapy was 58.9 months (27.6–88.1) and 69.1 months (35.6–124.5), respectively. 85% of LTS had a period off HER2 therapy, lasting a median of 30.4 months (8.2–NR).

Conclusions

LTS generally receive HER2-targeted therapies for periods of time longer than in clinical trials, but most LTS also had breaks in treatment. More research is needed to understand the effects of long-term treatment and to identify patients who may be able to safely discontinue HER2-targeted therapy.

     

Durable complete response in HER2-positive breast cancer: a multicenter retrospective analysis

Purpose

Though advanced and metastatic epidermal growth factor receptor 2 (HER2)-positive disease is not curable, a small proportion of patients with HER2-positive metastatic breast cancer remain in prolonged complete remission with anti-HER2 treatment. We hypothesized that some cases of HER2-positive metastatic breast cancer may be curable. In this large, multicenter retrospective study, we aimed to assess the long-term outcomes for patients with a durable response to trastuzumab.

Methods

We retrospectively evaluated the data of patients diagnosed with HER2-positive metastatic breast cancer who received trastuzumab for more than 2 years as the first-line treatment. Patients diagnosed between April 1, 2001 and December 31, 2014 at 19 institutions in Japan were included in the analysis. From 124 potential subjects, 16 were excluded and 108 were evaluated.

Results

The median follow-up length was 7.7 years. Disease progression occurred in 44/108 (40.7%) patients and 13/108 (12%) patients died. The median progression-free survival was 11.2 years, and as more than 80% of patients were alive 10 years after metastatic breast cancer diagnosis. Of the 108 patients, 57 achieved a clinical complete response. Trastuzumab therapy was interrupted for 27 (47.4%) of these patients (based on the doctor’s recommendation for 19 patients, owing to adverse events for 4 patients, owing to unknown reasons for 3 patients, and at the request of 1 patient). Disease progression occurred in 4 of the 27 patients after the interruption of trastuzumab treatment. The median duration of trastuzumab therapy for all 27 patients was 5.1 years (0.9–9.3 years).

Conclusion

We found that some patients showed no evidence of disease after the interruption of trastuzumab therapy. Discontinuation of maintenance trastuzumab in this patient population after a limited time should be explored cautiously while awaiting a global collaborative effort for a randomized trial.

     

HER4 expression in estrogen receptor-positive breast cancer is associated with decreased sensitivity to tamoxifen treatment and reduced overall survival of postmenopausal women

Background

The sensitivity of estrogen receptor-positive breast cancers to tamoxifen treatment varies considerably, and the molecular mechanisms affecting the response rates are manifold. The human epidermal growth factor receptor-related receptor HER2 is known to trigger intracellular signaling cascades that modulate the activity of coregulators of the estrogen receptor which, in turn, reduces the cell sensitivity to tamoxifen treatment. However, the impact of HER2-related receptor tyrosine kinases HER1, HER3, and, in particular, HER4 on endocrine treatment is largely unknown.

Methods

Here, we retrospectively evaluated the importance of HER4 expression on the outcome of tamoxifen- and aromatase inhibitor-treated estrogen receptor-positive breast cancer patients (n =?258). In addition, we experimentally analyzed the efficiency of tamoxifen treatment as a function of HER4 co-expression in vitro.

Results

We found a significantly improved survival in tamoxifen-treated postmenopausal breast cancer patients in the absence of HER4 compared with those with pronounced HER4 expression. In accordance with this finding, the sensitivity to tamoxifen treatment of estrogen and HER4 receptor-positive ZR-75-1 breast cancer cells can be significantly enhanced by HER4 knockdown.

Conclusion

We suggest an HER4/estrogen receptor interaction that impedes tamoxifen binding to the estrogen receptor and reduces treatment efficiency. Whether the sensitivity to tamoxifen treatment can be enhanced by anti-HER4 targeting needs to be prospectively evaluated.

     

HER2 genomic amplification in circulating tumor DNA and estrogen receptor positivity predict primary resistance to trastuzumab emtansine (T-DM1) in patients with HER2-positive metastatic breast cancer

Background

Trastuzumab emtansine (T-DM1) is approved for the treatment of patients with human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer (ABC), and has high efficacy. However, some patients exhibit primary resistance to T-DM1, and thus methods that can predict resistance in clinical practice are needed. Genomic analysis of circulating tumor DNA (ctDNA) in plasma is a non-invasive and reproducible method. This study aimed to predict primary resistance to T-DM1 by combining genomic analysis of ctDNA and other clinicopathological features of patients with HER2-positive ABC.

Methods

The study population comprised 34 patients with HER2-positive ABC who had been treated with T-DM1. Correlations between clinicopathological characteristics of patients and primary resistance to T-DM1 were examined, and HER2 gene copy number and PIK3CA gene mutations were analyzed using plasma ctDNA samples obtained from 16 patients before T-DM1 administration.

Results

Among the 34 patients, nine (26.5%) had progressive disease at the first efficacy analysis; these patients were considered to have primary resistance to T-DM1. No significant difference was found in the rate of primary resistance to T-DM1 between groups. Among 16 patients whose ctDNA was analyzed, four showed primary resistance to T-DM1. These four patients showed negative HER2 gene amplification in ctDNA and were ER-positive and/or PR-positive by immunohistochemistry.

Conclusions

HER2 gene amplification in ctDNA and ER and PR status may predict primary resistance to T-DM1. A liquid biopsy before the initiation of T-DM1 treatment could be a non-invasive way to predict whether a patient would exhibit primary resistance to T-DM1.

     

Phase II study of buparlisib (BKM120) and trastuzumab in patients with HER2+ locally advanced or metastatic breast cancer resistant to trastuzumab-based therapy

Purpose

A Phase Ib study in patients with trastuzumab-resistant, human epidermal growth factor receptor-2- (HER2)-positive advanced breast cancer defined the recommended Phase II dose of buparlisib as 100 mg/day in combination with 2 mg/kg weekly trastuzumab, and reported preliminary signs of clinical activity. Here we present results from the Phase II portion.

Methods

Patients with trastuzumab-resistant, HER2-positive advanced breast cancer received buparlisib plus trastuzumab. Study endpoints included safety/tolerability and antitumour activity. The study was extended to include a Phase Ib dose-escalation phase, in which patients with progressive brain metastases also received capecitabine.

Results

In the Phase II portion, of 50 patients treated with buparlisib and trastuzumab, the most common (≥ 30%) all-grade adverse events (AEs) were diarrhoea (54%), nausea (48%), decreased appetite, increased alanine aminotransferase (36% each), increased aspartate aminotransferase (34%), fatigue, rash (32% each), cough and hyperglycemia (30% each). One (2%) patient achieved complete response and four (8%) patients had confirmed partial responses [PR; including two patients with phosphatidylinositol 3-kinase (PI3 K) pathway-activated tumours]. Overall response rate (ORR) was 10%: the primary endpoint (ORR ≥ 25%) was therefore not met. In the Phase Ib portion, all patients with measurable brain lesions at baseline showed tumour shrinkage to some degree; due to low enrollment, maximum tolerated dose of buparlisib in combination with trastuzumab and capecitabine was not determined.

Conclusion

Buparlisib plus trastuzumab, as a chemotherapy-free regimen, demonstrated an acceptable safety profile but limited efficacy in patients with heavily pretreated, trastuzumab-resistant HER2-positive breast cancer, and in patients with progressive brain metastases also receiving capecitabine.

     

Effectiveness of neo-adjuvant systemic therapy with trastuzumab for basal HER2 type breast cancer: results from retrospective cohort study of Japan Breast Cancer Research Group (JBCRG)-C03

Purpose

While human epidermal growth factor receptor 2 (HER2) target therapies have significantly improved the prognosis of patients with HER2-enriched breast cancer, differing clinical benefits and gene expression analyses suggest a divergent HER2 subgroup. We aimed to investigate whether the basal HER2 subtype of breast cancer has distinguished characteristics.

Methods

We performed a substudy by using data from a retrospective multi-institutional cohort of JBCRG-C03. Between 2001 and 2011, we identified 184 eligible patients who received concurrent neo-adjuvant chemotherapy (NAC) with trastuzumab for hormone receptor-negative and HER2-positive breast cancer. We defined basal HER2 subtype breast cancer as HER2-positive, ER/PgR-negative, and basal markers (EGFR, CK14 or CK5/6) positive by immunohistochemistrical evaluation. The pathologic complete response (pCR) and disease-free survival (DFS) rates were compared between the two subtypes.

Results

A total of 127 (69.0%) patients achieved pCR after NAC and 29 (15.8%) patients experienced events of DFS within a 42 month median follow-up period (interquartile range 26–58 months). Although the basal HER2 subtype was related with poor DFS (3 year DFS: non-basal HER2, 95.0%; basal HER2, 86.9%; adjusted HR 3.4; 95% CI 1.2–14.5), neither the subtype (pCR: non-basal HER2, 75%; basal HER2, 66.7%; adjusted OR 0.60; 95% CI 0.27–1.28) nor the degree of expression of basal markers was significantly related with the pCR rate.

Conclusion

Basal HER2 phenotype showed poor DFS, but equivalent pCR rate after concurrent neo-adjuvant chemotherapy with trastuzumab. A different treatment approach to basal-HER2 type is needed even for cases that achieved adequate clinical response after NAC.

     

HER2 Activating Mutations in Estrogen Receptor Positive Breast Cancer

Purpose of Review

HER2 activating mutations are a new, druggable mutation identified by next-generation DNA sequencing (NGS) of breast cancer. Here, we review the recent data on the diagnosis and treatment of HER2 mutated, metastatic breast cancer.

Recent Findings

Pre-clinical studies have shown that HER2 activating mutations accelerate tumor growth and can be inhibited by HER2 targeted drugs, including trastuzumab and the second-generation, pan-HER tyrosine kinase inhibitor, neratinib. HER2 mutations can be diagnosed by NGS testing on either a tumor biopsy or circulating tumor DNA obtained from peripheral blood. Case reports provided initial evidence that HER2 targeted therapies can effectively treat patients with HER2 mutated, metastatic breast cancer. Two phase II clinical trials, MutHER and SUMMIT, both demonstrate that neratinib monotherapy has clinical efficacy for these patients, with clinical benefit rate of 31–40%.

Summary

HER2 targeted therapies are effective for HER2 mutated breast cancer but emergence of drug resistance remains a problem. Clinical trials are now testing neratinib-containing drug combination regimens for HER2 mutated, metastatic breast cancer patients.

     

Cardiac safety,efficacy, and correlation of serial serum HER2-extracellular domain shed antigen measurement with the outcome of the combined trastuzumab plus CMF in women with HER2-positive metastatic breast cancer: results from the EORTC 10995 phase II study

Purpose

Cardiotoxicity is a side effect of trastuzumab. We assessed efficacy and cardiac safety of CMF with trastuzumab (CMF+T) in HER2-positive metastatic breast cancer patients (MBC).

Methods

In this phase II study, centrally confirmed, previously treated HER2-positive MBC patients with measurable disease (per RECIST v 1.0) were enrolled. Initially, patients were randomized between 8 CMF cycles alone or combined with trastuzumab during chemotherapy, followed by 3-weekly trastuzumab maintenance till progression. A protocol amendment dropped the CMF arm and thereafter all patients received CMF+T. Translational research for prediction of treatment benefit was performed through serial serum HER2-shed antigen assessments.

Results

Ninety patients (CMF: 19; CMF+T: 71) were enrolled between 2002 and 2006. Median age was 54 years. 42 patients had prior chemotherapy (33 with anthracyclines) and 41/71 patients who received CMF+T continued trastuzumab monotherapy for a median duration of 40 weeks. Overall response rate was 50% for CMF+T (35/70) and 32% for CMF (6/19). Median duration of response was 10.3 months and 5.4 months, respectively. Median progression-free survival was 9.4 months (95% CI 8.1–11.6) and 4.8 months (95% CI 2.8–7.9), respectively. In the CMF+T arm, 13(18%) patients had an absolute LVEF decline, including 3 patients developing any grade of New York Heart Association cardiac dysfunction. Patients with an increase of 30% over baseline shed antigen had a higher progression risk (95% CI 7.6, 3.9–14.8).

Conclusions

CMF+T is effective, with an acceptable cardiotoxicity profile. LVEF declines were mostly asymptomatic and occurred irrespective of previous anthracycline exposure. CMF+T can be considered for these patients, if other cytotoxics are contraindicated.

     

Predictive factors of pathologic complete response of HER2-positive breast cancer after preoperative chemotherapy with trastuzumab: development of a specific predictor and study of its utilities using decision curve analysis

Purpose

The aim of this study was to assess the Institut Gustave Roussy/M.D. Anderson Cancer Center (IGR/MDACC) nomogram in predicting pathologic complete response (pCR) to preoperative chemotherapy in a cohort of human epidermal growth factor receptor 2 (HER2)-positive tumors treated with preoperative chemotherapy with trastuzumab. We then combine clinical and pathological variables associated with pCR into a new nomogram specific to HER2-positive tumors treated by preoperative chemotherapy with trastuzumab.

Patients and methods

Data from 270 patients with HER2-positive tumors treated with preoperative chemotherapy with trastuzumab at the Institut Curie and at the Georges François Leclerc Cancer Center were used to assess the IGR/MDACC nomogram and to subsequently develop a new nomogram for pCR based on multivariate logistic regression. Model performance was quantified in terms of calibration and discrimination. We studied the utility of the new nomogram using decision curve analysis.

Results

The IGR/MDACC nomogram was not accurate for the prediction of pCR in HER2-positive tumors treated by preoperative chemotherapy with trastuzumab, with poor discrimination (AUC = 0.54, 95% CI 0.51–0.58) and poor calibration (p = 0.01). After uni- and multivariate analysis, a new pCR nomogram was built based on T stage (TNM), hormone receptor status, and Ki67 (%). The model had good discrimination with an area under the curve (AUC) at 0.74 (95% CI 0.70–0.79) and adequate calibration (p = 0.93). By decision curve analysis, the model was shown to be relevant between thresholds of 0.3 and 0.7.

Conclusion

To the best of our knowledge, ours is the first nomogram to predict pCR in HER2-positive tumors treated by preoperative chemotherapy with trastuzumab. To ensure generalizability, this model needs to be externally validated.

     

Safety and immunogenicity of neoadjuvant treatment using WT1-immunotherapeutic in combination with standard therapy in patients with WT1-positive Stage II/III breast cancer: a randomized Phase I study

Purpose

This Phase I, multicenter, randomized study (ClinicalTrials.gov NCT01220128) evaluated the safety and immunogenicity of recombinant Wilms’ tumor 1 (WT1) protein combined with the immunostimulant AS15 (WT1-immunotherapeutic) as neoadjuvant therapy administered concurrently with standard treatments in WT1-positive breast cancer patients.

Methods

Patients were treated in 4 cohorts according to neoadjuvant treatment (A: post-menopausal, hormone receptor [HR]-positive patients receiving aromatase inhibitors; B: patients receiving chemotherapy; C: HER2-overexpressing patients on trastuzumab–chemotherapy combination; D: HR-positive/HER2-negative patients on chemotherapy). Patients (cohorts A–C) were randomized (2:1) to receive 6 or 8 doses of WT1-immunotherapeutic or placebo together with standard neoadjuvant treatment in a double-blind manner; cohort D patients received WT1-immunotherapeutic in an open manner. Safety was assessed throughout the study. WT1-specific antibodies were assessed pre- and post-vaccination.

Results

Sixty-two patients were randomized; 60 received ≥ one dose of WT1-immunotherapeutic. Two severe toxicities were reported: diarrhea (cohort C; also reported as a grade 3 serious adverse event) and decreased left ventricular ejection fraction (cohort B; also reported as a grade 2 adverse event). Post-dose 4 of WT1-immunotherapeutic, 10/10 patients from cohort A, 0/8 patients from cohort B, 6/11 patients from cohort C, and 2/3 patients from cohort D were humoral responders. The sponsor elected to close the trial prematurely.

Conclusions

Concurrent administration of WT1-immunotherapeutic and standard neoadjuvant therapy was well tolerated and induced WT1-specific antibodies in patients receiving neoadjuvant aromatase inhibitors. In patients on neoadjuvant chemotherapy or trastuzumab–chemotherapy combination, the humoral response was impaired or blunted, likely due to either co-administration of corticosteroids and/or the chemotherapies themselves.

     

A small-molecule inhibitor of SMAD3 attenuates resistance to anti-HER2 drugs in HER2-positive breast cancer cells

Purpose

Resistance against anti-HER2 drugs in HER2-positive breast cancer is a major obstacle to the improving prognosis. Transforming growth factor β (TGFβ) is a cytokine involved in the acquisition of more malignant phenotypes through epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC) properties. The aim of this study was to investigate the effects of TGFβ and its downstream SMAD pathway on resistance to anti-HER2 drugs.

Methods

HER2-positive breast cancer cell lines were stimulated with TGFβ for 14 days. Then, the sensitivity to trastuzumab and lapatinib and the expression levels of various EMT and CSC markers were examined. The correlation of nuclear SMAD3 expression in untreated breast tumor tissues with trastuzumab efficacy in neoadjuvant settings was examined. The effect of a small-molecule inhibitor of SMAD3 (SIS3) on resistance to anti-HER2 drugs was explored.

Results

We found that continuous activation of the TGFβ-SMAD3 pathway induced resistance to anti-HER2 drugs and CSC traits in HER2-positive breast cancer cells. The induction of drug resistance by TGFβ required strong activation of SMAD3. In fact, activated SMAD3 regulated multiple genes that harbor SMAD-binding elements and are involved in trastuzumab resistance. Nuclear SMAD3 expression in tumor tissue was inversely correlated with sensitivity to neoadjuvant treatment with trastuzumab. SIS3 not only prevented the acquisition of resistance to anti-HER2 drugs but also restored trastuzumab sensitivity in trastuzumab-resistant cells.

Conclusions

This study indicates that the TGFβ-SMAD3 pathway plays an important role in the induction and maintenance of resistance to anti-HER2 drugs. Thus, SMAD3 is a potential therapeutic target that can inhibit resistance and restore sensitivity to anti-HER2 drugs.