Trastuzumab plus anastrozole versus anastrozole alone for the treatment of postmenopausal women with human epidermal growth factor receptor 2-positive, hormone receptor-positive metastatic breast cancer: results from the randomized phase III TAnDEM study

SEOM clinical guidelines in advanced and recurrent breast cancer (2018)

Although the metastasic breast cancer is still an incurable disease, recent advances have increased significantly the time to progression and the overall survival. However, too much information has been produced in the last 2 years, so a well-based guideline is a valuable document in treatment decision making. The SEOM guidelines are intended to make evidence-based recommendations on how to manage patients with advanced and recurrent breast cancer to achieve the best patient outcomes based on a rational use of the currently available therapies. To assign a level of certainty and a grade of recommendation the United States Preventive Services Task Force guidelines methodology was selected as reference.

Endocrine Resistance in Hormone Receptor Positive Breast Cancer-From Mechanism to Therapy

The importance and role of the estrogen receptor (ER) pathway has been well-documented in both breast cancer (BC) development and progression. The treatment of choice in women with metastatic breast cancer (MBC) is classically divided into a variety of endocrine therapies, 3 of the most common being: selective estrogen receptor modulators (SERM), aromatase inhibitors (AI) and selective estrogen receptor down-regulators (SERD). In a proportion of patients, resistance develops to endocrine therapy due to a sophisticated and at times redundant interference, at the molecular level between the ER and growth factor. The progression to endocrine resistance is considered to be a gradual, step-wise process. Several mechanisms have been proposed but thus far none of them can be defined as the complete explanation behind the phenomenon of endocrine resistance. Although multiple cellular, molecular and immune mechanisms have been and are being extensively studied, their individual roles are often poorly understood. In this review, we summarize current progress in our understanding of ER biology and the molecular mechanisms that predispose and determine endocrine resistance in breast cancer patients.

Redrawing the Lines: The Next Generation of Treatment in Metastatic Breast Cancer

Although not considered curative in nature, new therapeutic advances in metastatic breast cancer (MBC) have substantially improved patient outcomes. This article discusses the state-of-the-art and emerging therapeutic options for management of MBC. BC systemic therapy targets multiple key pathways, including estrogen receptor signaling, HER2 signaling, and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling. Other therapeutic strategies include targeting DNA repair, inhibiting immune checkpoints, and developing antibody-drug conjugates. Although surgery historically was reserved for palliation of symptomatic, large, or ulcerating masses, some data suggest a possibly expanding role for more aggressive locoregional therapy in combination with systemic therapy. As technology develops, biomarker-specific, line-agnostic, and receptor-agnostic treatment strategies will redraw the current lines of MBC care. However, tumor heterogeneity remains a challenge. To effectively reshape our approach to MBC, careful consideration of the patient perspective, the costs and value of novel treatments, and accessibility (especially in developing countries) is paramount.

Therapeutic Options for Metastatic Breast Cancer

Metastatic breast cancer is the most common cancer in women after skin cancer, with a 5-year survival rate of 26%. Due to its high prevalence, it is important to develop therapies that go beyond those that just provide palliation of symptoms. Currently, there are several types of therapies available to help treat breast cancer including: hormone therapy, immunotherapy, and chemotherapy, with each one depending on both the location of metastases and morphological characteristics. Although technological and scientific advancements continue to pave the way for improved therapies that adopt a targeted and personalized approach, the fact remains that the outcomes of current first-line therapies have not significantly improved over the last decade. In this chapter, we review the current understanding of the pathology of metastatic breast cancer before thoroughly discussing local and systemic therapies that are administered to patients diagnosed with metastatic breast cancer. In addition, our review will also elaborate on the genetic profile that is characteristic of breast cancer as well as the local tumor microenvironment that shapes and promotes tumor growth and cancer progression. Lastly, we will present promising novel therapies being developed for the treatment of this disease.

Exceptional and Durable Responses to TDM-1 After Trastuzumab Failure for Breast Cancer Skin Metastases: Potential Implications of an Immunological Sanctuary

Breast Cancer (BC) skin metastases represent a challenging clinical scenario. Although they usually arise when other distant metastases are already present, they may also represent a form of locoregional recurrence (LRR). Systemic therapy in this setting may have a role both in case a radical locoregional approach is unfeasible in order to achieve disease control, and as adjuvant strategy after radical removal of cutaneous lesions, in order to prevent or delay subsequent disease spread. Systemic therapy for HER2+ metastatic BC (MBC) currently relies on anti-HER2 targeted agents. In this context TDM1 is an option in trastuzumab-resistant patients.Here we present 2 cases of isolated skin metastases in patients with HER2+ BC progressing during or early after trastuzumab-based therapy, showing impressive responses to TDM1. We hypothesize that the unique properties of skin immune microenvironment may explain the failure of trastuzumab, which exerts its action also through immunological mechanisms, and the subsequent outlier responses to TDM1, that relies on a partially different mechanism of action.

Endocrine Therapy for Breast Cancer: A Model of Hormonal Manipulation

Oestrogen receptor (ER) is the driving transcription factor in 70% of breast cancer. Endocrine therapies targeting the ER represent one of the most successful anticancer strategies to date. In the clinic, novel targeted agents are now being exploited in combination with established endocrine therapies to maximise efficacy. However, clinicians must balance this gain against the risk to patients of increased side effects with combination therapies. This article provides a succinct outline of the principles of hormonal manipulation in breast cancer, alongside the key evidence that underpins current clinical practice. As the role of endocrine therapy in breast cancer continues to expand, the challenge is to interpret the data and select the optimal strategy for a given clinical scenario.

Evolution of Targeted Therapy in Breast Cancer: Where Precision Medicine Began

As we consider best practices and approaches to targeted therapy in the clinic and in terms of trial design, breast cancer can serve as a useful model for other disease types, because estrogen receptor-positive and HER2-positive breast cancer have been known entities for several decades. In this review, we provide a history of the development of anti-estrogen therapy and anti-HER2-directed therapy and we discuss our growing understanding of resistance to targeted therapy as seen through this lens. We highlight some of the recent breakthroughs that have enhanced our understanding of resistance to endocrine and anti-HER2 therapy, and we discuss some of the ongoing research in the field.

Clinical Differences in Triple-Positive Operable Breast Cancer Subtypes in Korean Patients: An Analysis of Korean Breast Cancer Registry Data

Purpose

Triple-positive breast cancer is defined by estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) positivity. Several systemic breast cancer therapies target hormonal and HER2 responsiveness. We compared clinical outcomes of triple-positive disease with those of HER2-enriched and luminal HER2-negative disease and investigated the clinical efficacy of anti-HER2 therapy for triple-positive disease.

Methods

We retrospectively compared overall and recurrence-free survival among cases included in the Korean Breast Cancer Society (KBCS) and Seoul St. Mary's Hospital breast cancer registries and the therapeutic efficacy of trastuzumab for triple-positive and HER2-enriched cases.

Results

KBCS registry data (2006–2010; median follow-up, 76 months) indicated that patients with triple-positive breast cancer had intermediate survival between those with luminal A and HER2-enriched subtypes (p<0.001). Trastuzumab did not improve overall survival among patients with triple-positive breast cancer (p=0.899) in contrast to the HER2-enriched subtype (p=0.018). Seoul St. Mary's Hospital registry data indicated similar recurrence-free survival outcomes (p<0.001) and a lack of improvement with trastuzumab among patients with triple-positive breast cancer (median follow-up, 33 months; p=0.800). Multivariate analysis revealed that patients with triple-positive breast cancer had better overall survival than those with HER2-enriched disease and similar survival as those with the luminal A subtype (triple-positive: hazard ratio, 1.258, p=0.118; HER2-enriched: hazard ratio, 2.377, p<0.001).

Conclusion

Our findings showed that anti-HER2 therapy was less beneficial for treatment of triple-positive breast cancer than for HER2-enriched subtypes of breast cancer, and the triple-positive subtype had a distinct prognosis.

Characteristics and prognostic values of traditional pathological parameters and advanced molecular subtypes in women in Beijing with operable breast cancer: a retrospective analysis

OBJECTIVES

This study investigated the characteristics and prognostic values of traditional pathological parameters and advanced molecular subtypes in women with operable breast cancer in Beijing.

DESIGN

A retrospective study through case information enquiry or telephonic follow-up.

SETTING

Beijing Friendship Hospital.

PARTICIPANTS

1042 patients with primary operable breast cancer between 2008 and 2012 were enrolled in the study.

MEASURES

The characteristics and 5-year relapse rates according to the Nottingham Prognosis Index (NPI) and molecular subtypes were analysed.

RESULTS

In 1042 patients, the percentages of high histological grade, N1+N2, T2+T4 were 7.3%, 24.2%, 46.9%, respectively. In patients with invasive breast cancer, the percentages of auxiliary staging, positive margins, vascular invasion and nerve infiltration were 65.0%, 2.8%, 10.5% and 1.1%, respectively. The missing percentages of auxiliary staging, margins, vascular tumour invasion and nerve infiltration were 14.2%, 31.4%, 46.5% and 97.4%, respectively. The percentages of ER-positive, PR-positive, HER2-positive and Ki-67 high expression were 64.3%, 43.8%, 18.8% and 62.7%, respectively. The percentages of luminal A, luminal B, HER2-overexpression and basal-like breast cancers were 10.5%, 54.2%, 8.2% and 11.2%, respectively. Luminal A, luminal B and basal-like breast cancer subtypes were more common in the >60 years group, the 41-60 years group and the 20-40 years group, respectively. The 5-year relapse rates according to NPI were as follows: 6.2% in the low recurrence risk group, 10.4% in the moderate recurrence risk group and 12.9% in the high recurrence risk group. The 5-year relapse rates according to molecular subtypes were as follows: luminal A 4.0%, luminal B 7.0%, HER2-overexpression14.2%, basal-like 15.6%.

CONCLUSIONS

Reasonable analysis of traditional pathological parameters and advanced molecular subtypes in women with operable breast cancer in Beijing may be useful to guide precise treatment and predict prognosis.

A multicenter REtrospective observational study of first-line treatment with PERtuzumab, trastuzumab and taxanes for advanced HER2 positive breast cancer patients. RePer Study

We carried out a retrospective observational study of 264 HER2-positive advanced breast cancer (ABC) patients to explore the efficacy of first-line treatment with pertuzumab/trastuzumab/taxane in real-world setting. Survival data were analyzed by Kaplan Meier curves and log rank test. Median follow-up, length of pertuzumab/trastuzumab/taxane treatment and of pertuzumab, trastuzumab maintenance were 21, 4 and 15 months, respectively. The response rate was 77.3%, and the clinical benefit rate 93.6%. Median progression-free survival (mPFS) was 21 months, and median overall survival (mOS) was not reached. When comparing patients by trastuzumab-pretreatment, similar PFS were observed, although a longer OS was reached in trastuzumab-naïve patients (p = 0.02). Brain metastases at baseline and their development in course of therapy were associated with significantly shorter PFS (p = 0.0006) and shorter OS, although at a not fully statistically relevant extent (p = 0.06). The addition of maintenance endocrine therapy (ET) to pertuzumab/trastuzumab maintenance was associated with longer PFS (p = 0.0001), although no significant differences were detected in OS (p = 0.31). Results were confirmed by propensity score analysis (p = 0.003 and p = 0.46, respectively). In multivariate models, longer PFS was related to lower Performance Status (PS) (p = 0.07), metastatic stage at diagnosis (p = 0.006) and single metastatic site (p < 0.0001). An OS advantage was observed with lower PS (p < 0.0001), single metastatic site (p = 0.004), no prior exposure to trastuzumab (p = 0.004) and response to pertuzumab-based treatment (p = 0.003). Our results confirm that trastuzumab/pertuzumab/taxane is the standard of care as first-line treatment of patients with HER2-positive ABC even in the real-world setting. Moreover, the double-maintenance therapy (HER2 block and ET) is strongly recommended when feasible.

First-Line Trastuzumab Plus an Aromatase Inhibitor, With or Without Pertuzumab, in Human Epidermal Growth Factor Receptor 2–Positive and Hormone Receptor–Positive Metastatic or Locally Advanced Breast Cancer (PERTAIN): A Randomized, Open-Label Phase II Trial

Purpose

To assess pertuzumab plus trastuzumab and an aromatase inhibitor (AI) in patients with human epidermal growth factor receptor 2 (HER2)–positive and hormone receptor–positive metastatic/locally advanced breast cancer (MBC/LABC).

Patients and Methods

The PERTAIN trial (NCT01491737) is an ongoing randomized, open-label, multicenter—80 sites and eight countries—phase II trial. Patients have HER2-positive, hormone receptor–positive MBC/LABC and no prior systemic therapy with the exception of endocrine. Random assignment was 1:1 to intravenous pertuzumab (840 mg loading dose followed by 420 mg every 3 weeks) plus trastuzumab (8 mg/kg followed by 6 mg/kg every 3 weeks), and oral anastrozole (1 mg every day) or letrozole (2.5 mg every day), or trastuzumab and an AI. Induction intravenous docetaxel every 3 weeks or paclitaxel every week could be administered for 18 to 24 weeks at the investigator’s discretion (decided before but given after random assignment). Primary end point was progression-free survival (PFS). Patients were stratified by whether they received induction chemotherapy and their time since adjuvant hormone therapy.

Results

One hundred twenty-nine patients were randomly assigned per arm (February 2012 to October 2014; intent-to-treat populations); 75 in one arm and 71 in the other were chosen to receive induction chemotherapy. Stratified median PFS was 18.89 months (95% CI, 14.09 to 27.66 months) in the pertuzumab plus trastuzumab arm and 15.80 months (95% CI, 11.04 to 18.56 months) in the trastuzumab arm (stratified hazard ratio, 0.65; 95% CI, 0.48 to 0.89; P = .0070). Serious adverse events (AEs) were reported for 42 (33.1%) of 127 and 24 (19.4%) of 124 patients in the safety populations of the pertuzumab plus trastuzumab and trastuzumab arms, respectively. Rates of grade ≥ 3 AEs were 64 (50.4%) of 127 and 48 (38.7%) of 124, respectively. There were no deaths as a result of AEs.

Conclusion

PERTAIN met its primary PFS end point. Pertuzumab plus trastuzumab and an AI is effective for the treatment of HER2-positive MBC/LABC. The safety profile was consistent with previous trials of pertuzumab plus trastuzumab.

Extended Adjuvant Therapy with Neratinib Plus Fulvestrant Blocks ER/HER2 Crosstalk and Maintains Complete Responses of ER+/HER2+ Breast Cancers: Implications to the ExteNET Trial

PURPOSE

The phase III ExteNET trial showed improved invasive disease-free survival in patients with HER2⁺ breast cancer treated with neratinib versus placebo after trastuzumab-based adjuvant therapy. The benefit from neratinib appeared to be greater in patients with ER⁺/HER2⁺ tumors. We thus sought to discover mechanisms that may explain the benefit from extended adjuvant therapy with neratinib.Experimental Design: Mice with established ER⁺/HER2⁺ MDA-MB-361 tumors were treated with paclitaxel plus trastuzumab ± pertuzumab for 4 weeks, and then randomized to fulvestrant ± neratinib treatment. The benefit from neratinib was evaluated by performing gene expression analysis for 196 ER targets, ER transcriptional reporter assays, and cell-cycle analyses.

RESULTS

Mice receiving "extended adjuvant" therapy with fulvestrant/neratinib maintained a complete response, whereas those treated with fulvestrant relapsed rapidly. In three ER⁺/HER2⁺ cell lines (MDA-MB-361, BT-474, UACC-893) but not in ER⁺/HER2^- MCF7 cells, treatment with neratinib induced ER reporter transcriptional activity, whereas treatment with fulvestrant resulted in increased HER2 and EGFR phosphorylation, suggesting compensatory reciprocal crosstalk between the ER and ERBB RTK pathways. ER transcriptional reporter assays, gene expression, and immunoblot analyses showed that treatment with neratinib/fulvestrant, but not fulvestrant, potently inhibited growth and downregulated ER reporter activity, P-AKT, P-ERK, and cyclin D1 levels. Finally, similar to neratinib, genetic and pharmacologic inactivation of cyclin D1 enhanced fulvestrant action against ER⁺/HER2⁺ breast cancer cells.

CONCLUSIONS

These data suggest that ER blockade leads to reactivation of ERBB RTKs and thus extended ERBB blockade is necessary to achieve durable clinical outcomes in patients with ER⁺/HER2⁺ breast cancer.

Development of New Formulations of Biologics: Expectations, Immunogenicity, and Safety for Subcutaneous Trastuzumab

Subcutaneous (SC) trastuzumab has long been approved as a cancer treatment for early and advanced HER2-positive (HER2+) breast cancer by both the European Medicines Agency (EMA) and Agência Nacional de Vigilância Sanitária (ANVISA), the Brazilian National Health Surveillance Agency. A pivotal non-inferiority phase III trial, which aimed to provide a more convenient and cost-effective treatment in the HER2+ breast cancer neoadjuvant setting, showed that the SC group met prespecified efficacy endpoints and the SC formulation was considered as safe as the intravenous (IV) formulation. Considering the recent approval of several biosimilars, new SC formulations are also an interesting manufacturer strategy as these drugs can obtain patent protection. Despite being considered non-inferior to the IV formulation of trastuzumab, in clinical development, the SC formulation elicited higher immunogenicity, mainly related to overall anti-drug antibodies (ADAs); however, this finding was classified as clinically non-significant. In this article, we explore different aspects of the benefits and risks of the SC trastuzumab formulation according to published data.

National Cancer Institute Breast Cancer Steering Committee Working Group Report on Meaningful and Appropriate End Points for Clinical Trials in Metastatic Breast Cancer

PURPOSE

To provide evidence-based consensus recommendations on choice of end points for clinical trials in metastatic breast cancer, with a focus on biologic subtype and line of therapy.

METHODS

The National Cancer Institute Breast Cancer Steering Committee convened a working group of breast medical oncologists, patient advocates, biostatisticians, and liaisons from the Food and Drug Administration to conduct a detailed curated systematic review of the literature, including original reports, reviews, and meta-analyses, to determine the current landscape of therapeutic options, recent clinical trial data, and natural history of four biologic subtypes of breast cancer. Ongoing clinical trials for metastatic breast cancer in each subtype also were reviewed from ClinicalTrials.gov for planned primary end points. External input was obtained from the pharmaceutic/biotechnology industry, real-world clinical data specialists, experts in quality of life and patient-reported outcomes, and combined metrics for assessing magnitude of clinical benefit.

RESULTS

The literature search yielded 146 publications to inform the recommendations from the working group.

CONCLUSION

Recommendations for appropriate end points for metastatic breast cancer clinical trials focus on biologic subtype and line of therapy and the magnitude of absolute and relative gains that would represent meaningful clinical benefit.

The Genomic Landscape of Endocrine-Resistant Advanced Breast Cancers

We integrated the genomic sequencing of 1,918 breast cancers, including 1,501 hormone receptor-positive tumors, with detailed clinical information and treatment outcomes. In 692 tumors previously exposed to hormonal therapy, we identified an increased number of alterations in genes involved in the mitogen-activated protein kinase (MAPK) pathway and in the estrogen receptor transcriptional machinery. Activating ERBB2 mutations and NF1 loss-of-function mutations were more than twice as common in endocrine resistant tumors. Alterations in other MAPK pathway genes (EGFR, KRAS, among others) and estrogen receptor transcriptional regulators (MYC, CTCF, FOXA1, and TBX3) were also enriched. Altogether, these alterations were present in 22% of tumors, mutually exclusive with ESR1 mutations, and associated with a shorter duration of response to subsequent hormonal therapies.

Clinical benefit of fulvestrant monotherapy in the multimodal treatment of hormone receptor and HER2 positive advanced breast cancer: a case series

Fulvestrant is a pure estrogen receptor (ER) antagonist approved for the treatment of metastatic ER positive breast cancer in postmenopausal women with disease progression following antiestrogen therapy. The clinical results of fulvestrant demonstrated encouraging activity in tumors in spite of HER2 positivity, but data about its use after progression on anti-HER2 agents are limited. Partial responses and durations of response of 12, 25, and 38 months in three cases with multiple metastases of ER positive and HER2 positive breast cancer were observed; all patients had been treated with 1–4 regimens of an anti-HER2 agent in combination with chemotherapy or an aromatase inhibitor before the initiation of fulvestrant. Fulvestrant is a valuable option with limited toxicity and durable response in metastatic HER2 and ER positive breast cancer after progression on anti-HER2 agents as well. Therapeutic benefit even in extensive skin metastases and (irradiated) brain metastases may be expected. Further investigations are warranted to establish where it fits into the multimodal management of ER and HER positive breast cancer.

Trastuzumab-induced cardiotoxicity and its risk factors in real-world setting of breast cancer patients

PURPOSE

Cardiotoxicity is the most important side effect of trastuzumab treatment. Heart function monitoring is recommended during the treatment which has led to growing use of resources. The aim of this retrospective study was to determine the frequency and timing of trastuzumab cardiotoxicity and its risk factors in real-world setting.

METHODS

Single institute, retrospective collection of data on HER2+ breast cancer patients (n = 246) was carried out through a pharmacy search for patients who had received trastuzumab in 2006-2014. Clinical and pathological factors, treatment history, EF measurements, cardiac medications, cardiovascular disease history, cardiac symptoms, and survival data were collected from patient records.

RESULTS

32 patients (13%) had EF decline ≥ 10%, eleven (4.5%) had EF decline ≥ 20% within 1 year after trastuzumab initiation, and trastuzumab was discontinued due to suspected cardiotoxicity in six patients (2.4%). 49 patients (19.9%) experienced symptoms related to cardiotoxicity during therapy, which accumulated among those with EF drop. Underlying cardiovascular diseases and multiple (≥ 2) cardiac medications were related to EF drop (≥ 20%) and trastuzumab discontinuation. Majority of EF drops (≥ 10%) and trastuzumab discontinuations were seen within 6months of trastuzumab initiation and recovery of EF drop to < 10% of the baseline was seen in most cases (62.5%). There was no statistically significant difference in the survival of patients according to EF drop.

CONCLUSIONS

Trastuzumab cardiotoxicity seems to accumulate among patients with underlying cardiac conditions. EF monitoring could be targeted to risk groups without compromising of the cardiac health or survival of HER2-positive breast cancer patients.

The cellular and molecular effects of the androgen receptor agonist, Cl-4AS-1, on breast cancer cells

PURPOSE

The androgen receptor (AR) has attracted attention in the treatment of breast cancer. Due to the undesirable side effects of AR agonists, attempts have been undertaken to develop selective AR modulators. One of these compounds is Cl-4AS-1. This study examined this compound more closely at the cellular and molecular levels.

METHODS

Three different breast cancer cell lines were utilized, namely the luminal MCF-7 cells, the molecular apocrine MDA-MB-453 cells, and the triple negative, basal MDA-MB-231 cells.

RESULTS

High and significant concordance between dihydrotestosterone (DHT) and Cl-4AS-1 in regulation of gene expression in MDA-MB-453 cells was found. However, some differences were noted including the expression of AR, which was upregulated by DHT, but not Cl-4AS-1. In addition, both DHT and Cl-4AS-1 caused a similar morphological change and reorganization of the actin structure of MDA-MB-453 cells into a mesenchymal phenotype. Treatment of cells with DHT resulted in induction of proliferation of MCF-7 and MDA-MB-453 cells, but no effect was observed on the growth of MDA-MB-231 cells. On the other hand, increasing doses of Cl-4AS-1 resulted in a dose-dependent inhibition on the growth of the three cell lines. This inhibition was a result of induction of apoptosis whereby Cl-4AS-1 caused a block in entry of cells into the S-phase followed by DNA degradation.

CONCLUSIONS

These results indicate that although Cl-4AS-1 has characteristics of classical AR agonist, it has dissimilar properties that may make it useful in treating breast cancer.

Optimising endocrine therapy in postmenopausal women with advanced breast cancer

Hormone receptor-positive breast cancer is commonly treated with endocrine therapy (ET); however, over time, cancer cells can develop endocrine resistance. This review aims to document combination therapy and sequential therapy in the use of endocrine agents and targeted agents, by conducting two systematic searches using four databases: Cochrane Library, MEDLINE, EMBASE and Web of Science. A total of 26 studies that covered combination therapy were obtained and included for the review. Fourteen were phase III documenting combinations of mechanistic target of rapamycin (mTOR), phosphoinositide-3-kinase (PI3K), vascular endothelial growth factor receptor, human epidermal growth factor receptor 2 and cyclin-dependent kinase 4/6 (CDK4/6) inhibitors. The remaining studies were of phase II nature that reported combinations involving inhibitors in mTOR, endothelial growth factor receptor, CDK4/6 and TKI. Interesting findings in inhibitor combinations involving CDK4/6, mTOR and PI3K suggest clinical activity that can overcome endocrine resistance. On the other hand, there were 0 studies that covered sequential therapy. Overall findings showed that combination therapy improved treatment efficacy over monotherapy in postmenopausal patients with hormone receptor-positive advanced breast cancer. Inevitably, the benefits are accompanied with increased toxicity. To optimise ET, further research into combinations and effective patient selection will need to be defined. Additionally, this review warrants future studies to explore sequential therapy.

Overcoming Therapeutic Resistance of Triple Positive Breast Cancer with CDK4/6 Inhibition

Triple positive breast cancers overexpress both the human epidermal growth factor receptor 2 (HER2) oncogene and the hormonal receptors (HR) to estrogen and progesterone. These cancers represent a unique therapeutic challenge because of a bidirectional cross-talk between the estrogen receptor alpha (ERα) and HER2 pathways leading to tumor progression and resistance to targeted therapy. Attempts to combine standard of care HER2-targeted drugs with antihormonal agents for the treatment of HR+/HER2+ breast cancer yielded encouraging results in preclinical experiments but did improve overall survival in clinical trial. In this review, we dissect multiple mechanisms of therapeutic resistance typical of HR+/HER2+ breast cancer, summarize prior clinical trials of targeted agents, and describe novel rational drug combinations that include antihormonal agents, HER2-targeted drugs, and CDK4/6 inhibitors for treatment of the HR+/HER2+ breast cancer subtype.

Breast cancer-specific survival in patients with HER2-positive, node-negative T1a and T1b breast cancer

PURPOSE

There is limited data on prognosis of node-negative (N0), HER2-positive (HER2+) small breast cancers. We evaluated breast cancer-specific survival (BCSS) among women diagnosed with T1a/T1b, N0 tumors in California between 2000-2004 and 2005-2012, eras before and after approval of adjuvant trastuzumab.

PATIENTS AND METHODS

45,346 women diagnosed with T1a/b, N0 tumors between January 1, 2000 and December 31, 2012 were identified in the California Cancer Registry (CCR); approximately 10% were HER2 + , and 80% hormone receptor positive (ER and/or PR+). Primary outcome was BCSS, analyzed in 2000-2004 and 2005-2012. Multivariable Cox proportional hazards regression was used to calculate hazard ratios and 95% confidence intervals for mortality, and separately conducted for hormone receptor positive and negative tumors. Kaplan-Meier curves compared BCSS by HER2 status.

RESULTS

While BCSS in this cohort exceeded 90%, a significantly higher hazard of breast cancer death was observed in women with HER2+ tumors in the 2000-2004 era. There was no difference in outcomes between T1a and T1b tumors. Women with ER/PR+ tumors had lower hazards of death in both eras, but HER2+ tumors were associated with a higher hazard of death in the 2000-2004 era. Among women with hormone receptor negative tumors, HER2 positive disease was associated with a lower hazard of death in the 2005-2012 era.

CONCLUSION

Within this large cohort of T1a/b N0 breast cancers from the CCR, HER2+ tumors were associated with a significantly worse BCSS in the era before adjuvant trastuzumab. A balanced discussion regarding HER2-directed therapies is needed between patient and clinician.

Overcoming endocrine resistance in hormone receptor-positive breast cancer

Endocrine therapy, a major modality in the treatment of hormone receptor (hr)-positive breast cancer (bca), has improved outcomes in metastatic and nonmetastatic disease. However, a limiting factor to the use of endocrine therapy in bca is resistance resulting from the development of escape pathways that promote the survival of cancer cells despite estrogen receptor (er)-targeted therapy. The resistance pathways involve extensive cross-talk between er and receptor tyrosine kinase growth factors [epidermal growth factor receptor, human epidermal growth factor receptor 2 (her2), and insulin-like growth factor 1 receptor] and their downstream signalling pathways-most notably pi3k/akt/mtor and mapk. In some cases, resistance develops as a result of genetic or epigenetic alterations in various components of the signalling pathways, such as overexpression of her2 and erα co-activators, aberrant expression of cell-cycle regulators, and PIK3CA mutations. By combining endocrine therapy with various molecularly targeted agents and signal transduction inhibitors, some success has been achieved in overcoming and modulating endocrine resistance in hr-positive bca. Established strategies include selective er downregulators, anti-her2 agents, mtor (mechanistic target of rapamycin) inhibitors, and inhibitors of cyclin-dependent kinases 4 and 6. Inhibitors of pi3ka are not currently a treatment option for women with hr-positive bca outside the context of clinical trial. Ongoing clinical trials are exploring more agents that could be combined with endocrine therapy, and biomarkers that would help to guide decision-making and maximize clinical efficacy. In this review article, we address current treatment strategies for endocrine resistance, and we highlight future therapeutic targets in the endocrine pathway of bca.

Neratinib: Inching Up on the Cure Rate of HER2+ Breast Cancer?

Neratinib was recently approved by the FDA for extended adjuvant treatment of HER2⁺ breast cancer. The ExteNET trial showed improvement in invasive disease-free survival (iDFS) in the neratinib arm compared with placebo. The benefit was more pronounced in patients with estrogen receptor-positive (ER⁺)/HER2⁺ tumors, suggesting bidirectional cross-talk between the ER and HER pathways. Clin Cancer Res; 24(15); 3483-5. ©2018 AACRSee related article by Singh et al., p. 3486.

Combination therapies for the treatment of HER2-positive breast cancer: current and future prospects

INTRODUCTION

HER2-positive disease is an aggressive subtype of breast cancer that has been revolutionized by anti-HER2 directed therapies. Multiple drugs have been developed and are currently in clinical use, including trastuzumab, lapatinib, pertuzumab, T-DM1, and neratinib, alone or combined in 'dual HER2-blockade' regimens. Areas covered: A comprehensive literature review was performed regarding the current state and the future of combination regimens containing anti-HER2 agents, focusing on their efficacy, toxicity, and cost-effectiveness. Expert commentary: The combination of trastuzumab/pertuzumab is approved in all disease settings, while trastuzumab/neratinib is approved in the adjuvant setting and trastuzumab/lapatinib in metastatic disease. Meanwhile, as breast cancer biology and resistance mechanisms become clearer, combinations with drugs like PI3K/Akt/mTOR inhibitors, CDK4/6 inhibitors, anti-PD(L)1 antibodies, endocrine therapy, and new anti-HER2 agents (panHER and HER2 tyrosine kinase inhibitors, bispecific antibodies, anti-HER3 antibodies, and antibody-drug conjugates) are being extensively tested in clinical trials. More specific strategies for the 'triple-positive' (estrogen receptor-positive/HER2-positive) disease are also being explored. However, there is an urgent need for the development of predictive biomarkers for a better tailoring of anti-HER2 directed therapy. This is the only way to further improve clinical outcomes and quality of life and to decrease costs and toxicities of unnecessary treatments.

HER2-positive breast cancer: Current and new therapeutic strategies

Since the identification of the HER2 receptor amplification as an adverse prognostic factor that defined a special subtype of metastatic breast cancer, there has been a substantial improvement in survival of patients affected with this disease due to the development of anti-HER2 targeted therapies. The approval of trastuzumab and pertuzumab associated to a taxane in first line and subsequent treatment with the antibody-drug conjugate T-DM1 has certainly contributed to achieve these outcomes. The Tyrosine Kinase Inhibitor lapatinib was also approved in the basis of an improvement in progression free survival, becoming another commonly used treatment in combination with capecitabine. Inevitably, despite these therapeutic advances most patients progress on therapy due to primary or acquired resistance or because of an incorrect HER2 positivity assessment. Hence, it is crucial to correctly categorize HER2 amplified tumors and define mechanisms of resistance to design effective new treatment approaches. In addition, identifying biomarkers of response or resistance permits to tailor the therapeutic options for each patient sparing them from unnecessary toxicity as well as improving their outcomes. The aim of this review is to examine new strategies in development to treat HER2-positive metastatic breast cancer referring to the mechanisms of action of new drugs and new combinations including results reported so far.

Current Therapies for Human Epidermal Growth Factor Receptor 2-Positive Metastatic Breast Cancer Patients

The median survival of patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) has more than doubled, since the discovery of HER2-targeted treatments: it rose from less than 2 years in 2001 (prior introduction of trastuzumab) to more than 4 years in 2017. The initial generation of HER2-targeted therapies included trastuzumab with taxanes in the first line, followed by the addition of lapatinib and by a switch to another cytotoxic agent after progression. Results of CLEOPATRA, EMILIA, and TH3RESA trials have changed this clinical practice. The current consensus includes horizontal dual blockade (trastuzumab + pertuzumab) with taxanes or vinorelbine in the first line, followed by trastuzumab-emtansine (T-DM1) in the second line, with addition of lapatinib in the later lines of treatment. However, the fast and simultaneous development of new drugs led to a relative shortage of clinical evidence to support this sequence. Triple-positive breast cancers (TPBC), which express both hormonal receptors and HER2, constitute nearly half of HER2-positive cases. For these tumors, the current consensus is to add endocrine therapy after completion of cytotoxic treatment. Again, this consensus is not fully evidence-based. In view of the recent progress in treatment of estrogen-receptor positive breast cancers, a series of trials is evaluating addition of CDK4/6 inhibitors, aromatase inhibitors or fulvestrant to HER2-targeted and cytotoxic chemotherapy in TPBC patients. Despite the remarkable progress in treatment of HER2-positive breast cancer, metastatic disease is still incurable in the majority of patients. A wide range of novel therapies are under development to prevent and overcome resistance to current HER2-targeted agents. This review discusses pivotal clinical trials that have shaped current clinical practices, the current consensus recommendations, and the new experimental treatments in metastatic HER2-positive breast cancer.

An update on treatment for post-menopausal metastatic breast cancer in elderly patients

INTRODUCTION

Elderly patients make up a significant proportion of patients with metastatic breast cancer. With several options available in the metastatic setting for hormone positive breast cancer, these patients require an individualized approach to decision-making that considers multiple factors beyond performance status and chronologic age.

AREAS COVERED

The authors review the literature on endocrine monotherapy and combinations for hormone positive metastatic breast cancer, with specific commentary on the efficacy and toxicity for elderly patients. The authors describe the role of comprehensive geriatric assessment (CGA) and highlight the considerations for the use of bone modifying agents, and HER2-targeted therapy for hormone positive/HER2+ patients.

EXPERT OPINION

Evidence for elderly patients is largely based on subgroup analyses, which should be interpreted with caution. Nonetheless, elderly patients with metastatic hormone receptor positive breast cancer appear to derive similar benefit from treatments as younger patients. Similarly, for most drugs, these patients have no significant worsening of toxicity compared to younger patients. In addition to tumor biology, patient values and information from the CGA should be used to guide treatment decisions.

Cancer vaccines: translation from mice to human clinical trials

Therapeutic cancer vaccines have been a long-sought approach to harness the exquisite specificity of the immune system to treat cancer, but until recently have not had much success as single agents in clinical trials. However, new understanding of the immunoregulatory mechanisms exploited by cancers has allowed the development of approaches to potentiate the effect of vaccines by removing the brakes while the vaccines step on the accelerator. Thus, vaccines that had induced a strong T cell response but no clinical therapeutic effect may now reach their full potential. Here, we review a number of promising approaches to cancer vaccines developed initially in mouse models and their translation into clinical trials, along with combinations of vaccines with other therapies that might allow cancer vaccines to finally achieve clinical efficacy against many types of cancer.

Long-term trastuzumab (Herceptin®) treatment in a continuation study of patients with HER2-positive breast cancer or HER2-positive gastric cancer

BACKGROUND

Trastuzumab (Herceptin® [H]) is the standard of care for HER2-positive locally advanced/metastatic breast cancer and gastric/gastroesophageal junction (GEJ) cancer. However, there is a paucity of data available on long-term H treatment of patients. The Rollover Protocol (ROP) Study was conducted to report safety data for patients with HER2-positive locally advanced/metastatic breast and gastric/GEJ cancer who have received long-term H therapy (≥ 5 years and ≥ 3 years for breast and gastric/GEJ cancer, respectively).

METHODS

The ROP Study was a single-arm, multicenter, international continuation trial of H in patients who had previously completed a global Roche-sponsored trial with H therapy, had stable disease, and were receiving H at the end of the lead-in trial. Patients with chronic heart failure during the lead-in trial could be included following a risk-benefit analysis. The primary objectives were to provide H therapy to patients with HER2-overexpressing locally advanced/metastatic breast or gastric/GEJ cancer at the end of the lead-in study, and to follow the long-term outcomes and long-term overall safety in these patients.

RESULTS

Twenty-five of 69 patients enrolled in the ROP Study received long-term H therapy (19 breast cancer and 6 gastric/GEJ cancer). The median duration of H treatment for patients with breast cancer was 8 years 7 months, and 5 years 2 months for patients with gastric/GEJ cancer. The cardiac status of the patients remained stable over time, with no serious cardiac adverse events or marked changes in left ventricular ejection fraction (LVEF). The median overall worst LVEF measurement was 57.0%, and no patients experienced an LVEF of < 45% (range 47-63%). There were no serious adverse events related to study treatment.

CONCLUSIONS

These results suggest that H has an acceptable safety profile and was well tolerated in patients who received long-term H therapy (≥ 5 years and ≥ 3 years for breast and gastric/GEJ cancer, respectively). Further investigation and reporting of long-term H therapy would be valuable.

TRIAL REGISTRATION

This study was retrospectively registered on March 24, 2016 with Clinicaltrials.gov, number NCT02721641 .

Fulvestrant 500 mg vs 250 mg in postmenopausal women with estrogen receptor-positive advanced breast cancer: a randomized, double-blind registrational trial in China

The international CONFIRM study showed that fulvestrant 500 mg improved progression-free survival (PFS) vs fulvestrant 250 mg in postmenopausal women with estrogen receptor (ER)-positive locally advanced/metastatic breast cancer (LA/MBC). In this randomized, double-blind study, postmenopausal Chinese women with ER-positive LA/MBC and progression after endocrine therapy received fulvestrant 500 mg (days 0, 14, 28, and every 28 days thereafter) or fulvestrant 250 mg (every 28 days). Consistency with the international study was assumed if the hazard ratio (HR) for comparison of PFS (primary endpoint) was < 1 (stratified log-rank test). The study was not powered to assess between-group differences.

In total, 221 patients were randomized (fulvestrant 500 mg: n = 111; fulvestrant 250 mg: n = 110). Baseline characteristics were balanced. Median PFS was 8.0 months with fulvestrant 500 mg vs 4.0 months with 250 mg (HR = 0.75; 95% confidence interval [CI] 0.54−1.03; P = 0.078). PFS (HR; 95% CI) favored fulvestrant 500 mg in post-antiestrogen (0.86; 0.54−1.37) and post-aromatase inhibitor (0.65; 0.42−1.03) settings. No new safety considerations were observed. These results are consistent with the international CONFIRM study, supporting the superior clinical benefit of fulvestrant 500 mg in women with ER-positive LA/MBC experiencing progression following prior endocrine therapy.

Luminal B breast cancer: patterns of recurrence and clinical outcome

In recent years, most studies on breast cancer relapse and metastasis have focused on non-luminal breast cancers (including the basal-like and HER-2 subtypes) because of their poor prognosis. However, the luminal B subtype is more common, but this type has not been investigated as thoroughly. In the current study, we collected data on 258 patients with luminal-B breast cancer patients with recurrence and metastasis served as the observation group, and 189 patients with non-luminal breast cancer during the same period served as the control group. This study aimed to investigate the pattern of recurrence and clinical outcome after follow-up treatment for luminal B breast cancer. We found a higher proportion of local recurrence and single bone metastasis in patients with luminal B breast cancer than in patients in the non-luminal groups. The risk of recurrence and metastasis in patients with luminal B breast cancer during a 2- to 5-year period and after 5 years was still present, but the risk in patients with non-luminal breast cancers had obviously decreased during the same period. Patients with luminal B breast cancer with recurrence or/and metastasis had a better prognosis after reasonable treatment. The recurrence patterns and clinical outcomes of patients with luminal B breast cancer according to HER2 status were also different, to some degree. These results are of potential clinical relevance especially for the monitoring of clinical prognosis and targeted therapy intervention for luminal B breast cancer.

Efficacy and safety of trastuzumab, lapatinib, and paclitaxel neoadjuvant treatment with or without prolonged exposure to anti-HER2 therapy, and with or without hormone therapy for HER2-positive primary breast cancer: a randomised, five-arm, multicentre, open-label phase II trial

Background

Dual blockade of HER2 promises increased pathological complete response (pCR) rate compared with single blockade in the presence of chemotherapy for HER2-positive (+) primary breast cancer. Many questions remain regarding optimal duration of treatment and combination impact of endocrine therapy for luminal HER2 disease.

Methods

We designed a randomised phase II, five-arm study to evaluate the efficacy and safety of lapatinib and trastuzumab (6 weeks) followed by lapatinib and trastuzumab plus weekly paclitaxel (12 weeks) with/without prolongation of anti-HER2 therapy prior to chemotherapy (18 vs. 6 weeks), and with/without endocrine therapy in patients with HER2+ and/or oestrogen receptor (ER)+ disease. The primary endpoint was comprehensive pCR (CpCR) rate. Among the secondary endpoints, pCR (yT0-isyN0) rate, safety, and clinical response were evaluated.

Results

In total, 215 patients were enrolled; 212 were included in the full analysis set (median age 53.0 years; tumour size = T2, 65%; and tumour spread = N0, 55%). CpCR was achieved in 101 (47.9%) patients and was significantly higher in ER− patients than in ER+ patients (ER− 63.0%, ER+ 36.1%; P = 0.0034). pCR with pN0 was achieved in 42.2% of patients (ER− 57.6%, ER+ 30.3%). No significant difference was observed in pCR rate between prolonged exposure groups and standard groups. Better clinical response outcomes were obtained in the prolongation phase of the anti-HER2 therapy. No surplus was detected in pCR rate by adding endocrine treatment. No major safety concern was recognised by prolonging the anti-HER2 treatment or adding endocrine therapy.

Conclusions

This study confirmed the therapeutic impact of lapatinib, trastuzumab, and paclitaxel therapy for each ER− and ER+ subgroup of HER2+ patients. Development of further strategies and tools is required, particularly for luminal HER2 disease.

Electronic supplementary material

The online version of this article (10.1007/s12282-018-0839-7) contains supplementary material, which is available to authorized users.

Trastuzumab without chemotherapy in the adjuvant treatment of breast cancer: subgroup results from a large observational study

Background

The topic of trastuzumab therapy without chemotherapy in early breast cancer (EBC) has been repeatedly discussed at international consensus meetings, but is compromised by the lack of solid evidence from clinical studies.

Methods

An observational study database of patients with EBC receiving trastuzumab-containing (neo)adjuvant therapy was screened to identify those patients who did not receive cytostatic agents.

Results

Of 3935 patients, 232 (6%) were identified who received no chemotherapy, being characterized by older age, worse performance status, and/or less aggressive histology. Relapse-free survival in this cohort was 84% (95% confidence interval [CI] 78–89%) at 3 years and 80% (95% CI 74–87%) at 5 years. However, these rates were significantly worse than those in the group of patients who received chemotherapy (hazard ratio 1.49; 95% CI 1.06–2.09; P = 0.022). A similar pattern was observed for overall survival, with marginally non-significant inferiority in the group receiving no chemotherapy (hazard ratio 1.56; 95% CI 1.00–2.44; P = 0.052). Survival rates in patients receiving no chemotherapy were 93% (95% CI 88–97%) and 87% (95% CI 81–93%) at 3 and 5 years, respectively. These findings were confirmed by a propensity score analysis accounting for selection bias.

Conclusions

Trastuzumab plus chemotherapy should remain the preferred option in all patients with HER2-positive EBC with an indication for adjuvant treatment. However, a limited proportion of patients will need an alternative treatment approach, either because of contraindications or the patient’s preference. In these selected patients, trastuzumab monotherapy, eventually combined with endocrine agents, might be a reasonable option offering favorable long-term outcomes by addressing the high-risk profile associated with HER2-positive disease.

Lapatinib

The human epidermal growth factor receptor (HER) family of receptor tyrosine kinases plays an important role in the biology of many cancers. In breast and gastrointestinal cancer, and at lower rates also in additional tumor types, HER2 and its homo- or heterodimerization with HER1 or HER3 are essential for cancer cell growth and survival. Breast cancer patients overexpressing HER2 have a more aggressive course of their disease. The poor prognosis associated with HER2 overexpression can be substantially improved by adding HER2-targeted therapy to standard of care using the monoclonal antibody trastuzumab. Lapatinib, an oral dual tyrosine kinase inhibitor, blocks HER1 and HER2 tyrosine kinase activity by binding to the ATP-binding site of the receptor's intracellular domain, resulting in inhibition of tumor cell growth. Lapatinib is generally well tolerated with diarrhea being the most common adverse effect. However, although being mainly of mild to moderate severity, interruption or discontinuation of treatment has been reported in a substantial proportion of patients in clinical trials. In 2007, lapatinib has been approved in combination with capecitabine in patients with advanced HER2-positive breast cancer upon progressive disease following standard therapy with anthracyclines, taxanes, and trastuzumab. In 2013, the approval was extended to a chemotherapy-free combination with trastuzumab for patients with metastatic HER2-positive, hormone receptor-negative breast cancer progressing on prior trastuzumab and chemotherapy. Since 2010, lapatinib is approved in combination with letrozole in the treatment of postmenopausal women with advanced HER2- and hormone receptor-positive breast cancer. In contrast, in first-line cytotoxic-based therapy of both early and advanced HER2-positive breast cancer, data from clinical trials did not provide evidence of additional benefit of lapatinib compared to trastuzumab. Moreover, over the past few years, novel HER2-targeted drugs, either alone or as a combined anti-HER2 approach, have been extensively evaluated, demonstrating a more favorable outcome. Also, neither in first- nor second-line treatment of advanced gastric cancer, lapatinib has been proven to be superior compared to trastuzumab as hitherto standard of care HER2 blockade. Therefore, lapatinib has become somewhat less important in patients with HER2-positive breast cancer during the past 10 years since its first introduction. Nevertheless, consideration of treatment with lapatinib appears to be reasonable in selected patients not only in the approved applications but also beyond, and further indications such as HER2-positive refractory metastatic colorectal cancer may arise in future. Also, lapatinib may have distinct advantages over antibodies in targeting truncated HER2 and crossing the blood-brain barrier. Finally, the favorable cardiac toxicity profile of lapatinib makes it an attractive alternative to trastuzumab-based regimens in patients at risk for cardiac events.

Cardiac biomarkers for early detection and prediction of trastuzumab and/or lapatinib-induced cardiotoxicity in patients with HER2-positive early-stage breast cancer: a NeoALTTO sub-study (BIG 1-06)

BACKGROUND

Biomarkers of cardiac damages, such as troponin T (TnT) and the amino-terminal fragment of brain natriuretic peptide (NT-proBNP), may be useful as early predictors of cardiac dysfunction. The role of these biomarkers in patients receiving lapatinib and/or trastuzumab before anthracyclines is unknown. This study explores TnT and NT-proBNP as predictors of early cardiac toxicity in neoadjuvant breast cancer patients.

METHODS

This sub-study of the NEOALTTO trial tested if changes in the levels of TnT and NT-proBNP occurred after 2 weeks of anti-HER2 therapy (lapatinib, trastuzumab or their combination) alone and/or after 18 weeks of anti-HER2 therapy plus weekly paclitaxel.

RESULTS

173 and 172 were tested at all three timepoints for NT-proBNP and TnT, respectively. The incidence of biomarker elevation was overall low at all timepoints for all the three treatment arms. A total of 13 CEs in 11 patients occurred. Biomarker elevations in patients with CEs were very rare; only one patient with subsequent CE had a NT-proBNP elevation at baseline and at week 2.

CONCLUSION

These results suggest that TnT and proBNP may not be useful as early predictors of cardiac toxicity in anthracycline-naïve patients receiving trastuzumab and/or lapatinib.

Phase III, Randomized Study of Dual Human Epidermal Growth Factor Receptor 2 (HER2) Blockade With Lapatinib Plus Trastuzumab in Combination With an Aromatase Inhibitor in Postmenopausal Women With HER2-Positive, Hormone Receptor-Positive Metastatic Breast Cancer: ALTERNATIVE

Purpose Human epidermal growth factor receptor 2 (HER2) targeting plus endocrine therapy (ET) improved clinical benefit in HER2-positive, hormone receptor (HR)-positive metastatic breast cancer (MBC) versus ET alone. Dual HER2 blockade enhances clinical benefit versus single HER2 blockade. The ALTERNATIVE study evaluated the efficacy and safety of dual HER2 blockade plus aromatase inhibitor (AI) in postmenopausal women with HER2-positive/HR-positive MBC who received prior ET and prior neo(adjuvant)/first-line trastuzumab (TRAS) plus chemotherapy. Methods Patients were randomly assigned (1:1:1) to receive lapatinib (LAP) + TRAS + AI, TRAS + AI, or LAP + AI. Patients for whom chemotherapy was intended were excluded. The primary end point was progression-free survival (PFS; investigator assessed) with LAP + TRAS + AI versus TRAS + AI. Secondary end points were PFS (comparison of other arms), overall survival, overall response rate, clinical benefit rate, and safety. Results Three hundred fifty-five patients were included in this analysis: LAP + TRAS + AI (n = 120), TRAS + AI (n = 117), and LAP + AI (n = 118). Baseline characteristics were balanced. The study met its primary end point; superior PFS was observed with LAP + TRAS + AI versus TRAS + AI (median PFS, 11 v 5.7 months; hazard ratio, 0.62; 95% CI, 0.45 to 0.88; P = .0064). Consistent PFS benefit was observed in predefined subgroups. Overall response rate, clinical benefit rate, and overall survival also favored LAP + TRAS + AI. The median PFS with LAP + AI versus TRAS + AI was 8.3 versus 5.7 months (hazard ratio, 0.71; 95% CI, 0.51 to 0.98; P = .0361). Common adverse events (AEs; ≥ 15%) with LAP + TRAS + AI, TRAS + AI, and LAP + AI were diarrhea (69%, 9%, and 51%, respectively), rash (36%, 2%, and 28%, respectively), nausea (22%, 9%, and 22%, respectively), and paronychia (30%, 0%, and 15%, respectively), mostly grade 1 or 2. Serious AEs were reported similarly across the three groups, and AEs leading to discontinuation were lower with LAP + TRAS + AI. Conclusion Dual HER2 blockade with LAP + TRAS + AI showed superior PFS benefit versus TRAS + AI in patients with HER2-positive/HR-positive MBC. This combination offers an effective and safe chemotherapy-sparing alternative treatment regimen for this patient population.

Phase III, Randomized Study of Dual Human Epidermal Growth Factor Receptor 2 (HER2) Blockade With Lapatinib Plus Trastuzumab in Combination With an Aromatase Inhibitor in Postmenopausal Women With HER2-Positive, Hormone Receptor-Positive Metastatic Breast Cancer: ALTERNATIVE

Purpose Human epidermal growth factor receptor 2 (HER2) targeting plus endocrine therapy (ET) improved clinical benefit in HER2-positive, hormone receptor (HR)-positive metastatic breast cancer (MBC) versus ET alone. Dual HER2 blockade enhances clinical benefit versus single HER2 blockade. The ALTERNATIVE study evaluated the efficacy and safety of dual HER2 blockade plus aromatase inhibitor (AI) in postmenopausal women with HER2-positive/HR-positive MBC who received prior ET and prior neo(adjuvant)/first-line trastuzumab (TRAS) plus chemotherapy. Methods Patients were randomly assigned (1:1:1) to receive lapatinib (LAP) + TRAS + AI, TRAS + AI, or LAP + AI. Patients for whom chemotherapy was intended were excluded. The primary end point was progression-free survival (PFS; investigator assessed) with LAP + TRAS + AI versus TRAS + AI. Secondary end points were PFS (comparison of other arms), overall survival, overall response rate, clinical benefit rate, and safety. Results Three hundred fifty-five patients were included in this analysis: LAP + TRAS + AI (n = 120), TRAS + AI (n = 117), and LAP + AI (n = 118). Baseline characteristics were balanced. The study met its primary end point; superior PFS was observed with LAP + TRAS + AI versus TRAS + AI (median PFS, 11 v 5.7 months; hazard ratio, 0.62; 95% CI, 0.45 to 0.88; P = .0064). Consistent PFS benefit was observed in predefined subgroups. Overall response rate, clinical benefit rate, and overall survival also favored LAP + TRAS + AI. The median PFS with LAP + AI versus TRAS + AI was 8.3 versus 5.7 months (hazard ratio, 0.71; 95% CI, 0.51 to 0.98; P = .0361). Common adverse events (AEs; ≥ 15%) with LAP + TRAS + AI, TRAS + AI, and LAP + AI were diarrhea (69%, 9%, and 51%, respectively), rash (36%, 2%, and 28%, respectively), nausea (22%, 9%, and 22%, respectively), and paronychia (30%, 0%, and 15%, respectively), mostly grade 1 or 2. Serious AEs were reported similarly across the three groups, and AEs leading to discontinuation were lower with LAP + TRAS + AI. Conclusion Dual HER2 blockade with LAP + TRAS + AI showed superior PFS benefit versus TRAS + AI in patients with HER2-positive/HR-positive MBC. This combination offers an effective and safe chemotherapy-sparing alternative treatment regimen for this patient population.

Ongoing unmet needs in treating estrogen receptor-positive/HER2-negative metastatic breast cancer

Estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) advanced or metastatic breast cancer (MBC) is the most common MBC subtype and currently remains incurable, with a median overall survival of 24.8 months (95% confidence interval, 21.3-30.3). Common sites of metastases are bone, viscera, and brain, causing significant symptoms that negatively affect patient functioning, quality of life (QoL), and work productivity. Guidelines state that endocrine therapy (ET) is preferable to chemotherapy as first-line treatment for patients with ER+ MBC, regardless of limited visceral metastases, unless rapid tumor response is required or ET resistance is suspected. Although response rates up to 40% have been reported for first-line MBC treatment, the majority of initial responders eventually develop ET resistance. Notwithstanding the steep decline in efficacy between first and later lines of ET, some patients may receive chemotherapy earlier than necessary. Although new treatments have been approved for patients with ER+/HER2- advanced or MBC in the past decade, neither survival nor QoL appear to have improved significantly. Thus, there remain significant unmet needs for this patient population, including improved survival, maintaining or improving patient QoL, and emphasizing the importance of treatment selection to assist healthcare practitioners managing patient care. In this review, we identify current challenges and unmet needs in this patient population, review cutting-edge treatments, and provide clinically relevant suggestions for treatment selection that can optimize outcomes and patients' health-related QoL.

Optimal Management of Early and Advanced HER2 Breast Cancer

Approximately 15%-20% of breast cancer is HER2 positive, and patients with this subtype of disease historically had worse outcomes than patients with HER2-negative disease. However, the introduction of HER2-directed therapies has dramatically altered outcomes for these patients, especially for persons with early disease. However, despite these achievements, metastatic disease is still not curable. This review summarizes the current treatment approach for patients in the preoperative and adjuvant setting, including data regarding selecting the optimal chemotherapy partner as well as determining the duration and type of anti-HER-directed therapy. This article also reviews how to approach patients with advanced HER2-positive disease and discusses promising new therapies that are in development.