Optimal duration of adjuvant trastuzumab in treatment of early breast cancer: a meta-analysis of randomized controlled trials

SEOM-GEICAM-SOLTI clinical guidelines for early-stage breast cancer (2022)

Breast cancer is the leading cause of cancer in women in Spain and its annual incidence is rapidly increasing. Thanks to the screening programs in place, nearly 90% of breast cancer cases are detected in early and potentially curable stages, despite the COVID-19 pandemic possibly having impacted these numbers (not yet quantified). In recent years, locoregional and systemic therapies are increasingly being directed by new diagnostic tools that have improved the balance between toxicity and clinical benefit. New therapeutic strategies, such as immunotherapy, targeted drugs, and antibody-drug conjugates have also improved outcomes in some patient subgroups. This clinical practice guideline is based on a systematic review of relevant studies and on the consensus of experts from GEICAM, SOLTI, and SEOM.

Three-year disease-free survival in randomized trials of neoadjuvant chemotherapy and HER2-targeted therapy in breast cancer: A meta-analysis

BACKGROUND

Outcomes for breast cancer patients with residual disease (RD) after neoadjuvant chemotherapy (NACT) and HER2-targeted therapy may be better than anticipated leading to a smaller absolute benefit of adjuvant trastuzumab emtansine (T-DM1). Therefore, accurate estimates of 3-year disease-free survival (DFS) can aid in treatment planning.

METHODS

We reviewed randomized trials of NACT and HER2-targeted therapy in breast cancer (excluding T-DM1) and calculated mean 3-year DFS weighted by study sample size. Meta-regression comprising linear regression weighted by sample size (mixed-effects) was performed to explore associations between 3-year DFS and year of accrual and trial-level patient, disease, and treatment factors. Data were reported quantitatively irrespective of statistical significance.

RESULTS

Eleven studies (N = 3581) were included in the primary analysis. The mean 3-year DFS for patients with RD was 79.7% (95% CI 77.4-80.9). This was higher for trials completing accrual after 2010 [83% (95% CI 79.3-86.3)] and for those receiving dual HER2 targeted therapy [83.4% (95% CI 79.2-87.7]. Better outcomes for ER positivity, later accrual and dual Her-2 targeted therapy were confirmed in meta-regression. Negative quantitative significance was observed for larger clinical tumor size and nodal involvement.

CONCLUSIONS

The 3-year DFS for patients with RD has improved over time possibly due to dual HER2 targeted therapy. This will reduce the absolute benefit of adjuvant T-DM1 in this group of patients.

Cardiotoxicity among socioeconomically marginalized breast cancer patients

Purpose

Evidence of cardiotoxicity risk related to anthracycline or trastuzumab exposure is largely derived from breast cancer cohorts that under-represent socioeconomically marginalized women, who may be at increased risk of cardiotoxicity because of high prevalence of cardiovascular disease risk factors. Therefore, we aimed to estimate cardiotoxicity risk among socioeconomically marginalized breast cancer patients treated with anthracyclines or trastuzumab and describe clinical consequences of cardiotoxicity.

Methods

We linked electronic health records with institutional registry data from a Comprehensive Community Cancer Program within a safety-net health system. Eligible patients were adult females, diagnosed with first primary invasive breast cancer between 2013 and 2017, and initiated anthracyclines or trastuzumab as part of first-line therapy. We estimated cumulative incidence (risk) of cardiotoxicity with corresponding 95% confidence limits (CL) using the Aalen-Johansen estimator with death as competing risk.

Results

Our study population comprised 169 women with breast cancer (103 initiated anthracyclines and 66 initiated trastuzumab). Cumulative incidence of cardiotoxicity was 21% (95% CL: 12%, 32%) at one year and 25% (95% CL: 15%, 35%) at three years among women who initiated trastuzumab, whereas cumulative incidence was 3.9% (95% CL: 1.3%, 8.9%) at one year and 5.9% (95% CL: 2.4%, 12%) at three years among women who initiated anthracyclines. More than half of patients with cardiotoxicity experienced interruption of cancer treatment.

Conclusion

Our findings suggest high risk of cardiotoxicity among socioeconomically marginalized breast cancer patients after initiation of anthracyclines or trastuzumab. Strategies are needed for optimizing cancer treatment effectiveness while minimizing cardiotoxicity in this population.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10549-022-06695-0.

Evolving Role of Risk Tailored Therapy in Early Stage HER2-Positive Breast Cancer: A Canadian Perspective

The advent of HER2-targeted therapies has led to an important shift in the management of HER2-positive early breast cancer. However, initial treatment approaches apply uniform treatment regimens to all patients, with significant treatment-related and financial toxicities for both the patient and the health care system. Recent data demonstrates that for many patients, the chemotherapy backbone, duration and nature (mono- versus dual-targeted therapy) of the HER2 blockade can be better targeted to an individual patient’s risk of recurrence. We will provide a review of current data supporting risk tailored therapy in early stage HER2-positive breast cancer along with key completed and ongoing Canadian and international risk tailored trials. Neoadjuvant systemic therapy should now be considered for patients with clinical stage 2 disease, with greater use of non-anthracycline based chemotherapy regimens. Patients with residual disease following neoadjuvant therapy should be considered for escalated treatment with adjuvant T-DM1. Patients with stage I disease can often be managed with upfront surgery and evidence-based de-escalated adjuvant chemotherapy regimens. The modest benefit of 12- versus 6 months of adjuvant HER2 therapy and/or dual adjuvant HER2 therapy should be carefully weighed against the toxicities. All patients with HER2-positive breast cancer should be enrolled in ongoing risk tailored treatment trials whenever possible. Increasing data supports risk tailored therapy in early stage HER2-positive breast cancer in place of the routine application of aggressive and toxic systemic therapy regimens to all patients. While much progress has been made towards treatment de-escalation in appropriate patients, more is needed, as we highlight in this review. Indeed, Canadian-led clinical trials are helping to lead these efforts.

Interventions for Preventing Cardiotoxicity in Breast Cancer Patients Receiving Trastuzumab: A Systemic Review and Bayesian Network Meta-Analysis

Background: Trastuzumab is associated with the risk of cardiotoxicity. Here, we aim to explore interventions for preventing trastuzumab-related cardiotoxic effects in breast cancer patients.

Methods: A systematic review was performed including trials of breast cancer patients with intervention to prevent cardiotoxicity of trastuzumab. Trials were searched through databases including PubMed, Embase, and Cochrane Library.

Results: Eight RCTs were included. Five trials reported the outcomes of short-duration interventions, including 6-month and 9-week durations, and only 9-week treatment has a significant difference from the 12-month group (OR 0.38; 95% CI 0.18–0.83) using cardiotoxicity as the outcome. However, 6-month treatment turned out to yield less occurrence of trastuzumab discontinuation (OR 0.32; 95% CI 0.24–0.42). Three trials reported interventions of cardioprotective drugs, and there is no significant difference shown in any cardioprotective group compared with placebo (cardiotoxicity outcome: angiotensin-converting enzyme inhibitor: OR 0.48; 95% CI 0.057–2.3; angiotensin receptor blocker: OR 1.3; 95% CI 0.12–14; β-blocker: OR 0.48; 95% CI 0.057–2.3; trastuzumab interruption outcome: angiotensin-converting enzyme inhibitor: OR 0.45; 95% CI 0.12–1.3; angiotensin receptor blocker: OR 0.87; 95% CI 0.15–4.8; β-blocker: OR 0.41; 95% CI 0.11–1.2).

Conclusion: Only the 9-week group has a significant difference from the 12-month group using cardiotoxicity as the outcome. And 6-month treatment turned out to yield less occurrence of trastuzumab discontinuation. The use of cardioprotective drugs failed to prevent trastuzumab-related cardiotoxic effects in breast cancer patients.

Management of Early-Stage Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer

The addition of trastuzumab to chemotherapy dramatically improved the prognosis of early-stage human epidermal growth factor receptor 2 (HER2)-positive breast cancer. However, 15%-31% of patients still develop disease recurrence, on the basis of long-term follow-up of adjuvant pivotal trials. A better understanding of tumor biology has led to the development of optimized anti-HER2 drugs and add-on strategies to further improve survival outcomes. In the neoadjuvant setting, dual HER2 blockade with trastuzumab and pertuzumab plus chemotherapy has increased the rate of pathologic complete response, a surrogate marker of improved long-term outcome; yet, in the adjuvant setting, it has led to small benefits in invasive disease-free survival. Extended adjuvant therapy with the irreversible pan-HER2 inhibitor neratinib is an option for selected patients with HER2-positive and estrogen receptor-positive disease who have received neoadjuvant or adjuvant chemotherapy plus trastuzumab. Additionally, the use of the antibody-drug conjugate trastuzumab-emtansine has led to a significant improvement in invasive disease-free survival for patients with residual disease following neoadjuvant therapy and has taught us the importance of using preoperative therapy to adapt adjuvant treatment. Nevertheless, recurrences in the brain remain an important caveat, and not all patients benefit to the same extent from anti-HER2 therapies. Biologic heterogeneity within HER2-positive disease may modulate treatment response and prognosis. De-escalating treatment strategies to avoid unnecessary treatments and toxicities, without compromising outcomes, have become a crucial focus of research. To stratify patient risks and optimize treatment selection, other biomarkers including intrinsic subtype, level of HER2, and tumor-infiltrating lymphocytes should be further evaluated. We discuss the latest evidence on the current approach of early-stage, HER2-positive breast cancer and present future perspectives on its management.

Risk-based decision-making in the treatment of HER2-positive early breast cancer: Recommendations based on the current state of knowledge

Treatment of HER2-positive early breast cancer (EBC) continues to evolve with neoadjuvant (pre-operative) and adjuvant (post-operative) HER2-targeted therapies as standard of care. There are two important decision points. The first involves deciding between neoadjuvant therapy or proceeding directly to surgery. Neoadjuvant chemotherapy (NACT) plus pertuzumab-trastuzumab is appropriate for patients with high-risk HER2-positive EBC (tumour diameter ≥2 cm, and/or node-positive disease). Patients with node-negative disease and tumour diameter <2 cm are candidates for upfront surgery followed by paclitaxel for 12 weeks plus 18 cycles of trastuzumab, with the option to add pertuzumab (if pN+). The second decision point involves the pathohistological result at surgery after neoadjuvant therapy. Total pathological complete response (tpCR: ypT0/is, ypN0) is associated with improved survival endpoints. Patients with tumours ≥2 cm and/or node-positive disease at diagnosis who have a tpCR after dual blockade should continue pertuzumab-trastuzumab in the adjuvant setting to complete 1 year (18cycles) of treatment. For patients with invasive residual disease, 14cycles of post-neoadjuvant trastuzumab emtansine (T-DM1) therapy significantly increases invasive-DFS compared with trastuzumab. Extended adjuvant therapy with neratinib is an option in selected patients (HER2-positive and oestrogen receptor [ER]-positive) who have completed adjuvant trastuzumab-based therapy. Less aggressive chemotherapy regimens are recommended in populations with a lower risk of recurrence (patients with small tumours without axillary involvement; patients unlikely to tolerate anthracycline-taxane or taxane-carboplatin regimens). Ultimately, treatment recommendations should be consistent with local and international guidelines. Further studies will guide optimisation of treatment for patients with HER2-positive EBC according to the risk of disease recurrence.

Adjuvant Pertuzumab and Trastuzumab in Early HER2-Positive Breast Cancer in the APHINITY Trial: 6 Years' Follow-Up

PURPOSE

APHINITY, at 45 months median follow-up, showed that pertuzumab added to adjuvant trastuzumab and chemotherapy significantly improved invasive disease–free survival (IDFS) (hazard ratio 0.81 [95% CI, 0.66 to 1.00], P = .045) for patients with early human epidermal growth factor receptor 2 (HER2)–positive breast cancer (BC), specifically those with node-positive or hormone receptor (HR)–negative disease. We now report the preplanned second interim overall survival (OS) and descriptive updated IDFS analysis with 74 months median follow-up.

METHODS

After surgery and central HER2-positive confirmation, 4,805 patients with node-positive or high-risk node-negative BC were randomly assigned (1:1) to either 1-year pertuzumab or placebo added to standard adjuvant chemotherapy and 1-year trastuzumab.

RESULTS

This interim OS analysis comparing pertuzumab versus placebo did not reach the P = .0012 level required for statistical significance ( P = .17, hazard ratio 0.85). Six-year OS were 95% versus 94% with 125 deaths (5.2%) versus 147 (6.1%), respectively. IDFS analysis based on 508 events (intent-to-treat population) showed a hazard ratio of 0.76 (95% CI, 0.64 to 0.91) and 6-year IDFS of 91% and 88% for pertuzumab and placebo groups, respectively. The node-positive cohort continues to derive clear IDFS benefit from pertuzumab (hazard ratio 0.72 [95% CI, 0.59 to 0.87]), 6-year IDFS being 88% and 83%, respectively. Benefit was not seen in the node-negative cohort. In a subset analysis, IDFS benefit from pertuzumab showed a hazard ratio of 0.73 (95% CI, 0.59 to 0.92) for HR-positive disease and a hazard ratio of 0.83 (95% CI, 0.63 to 1.10) for HR-negative disease. Primary cardiac events remain < 1% in both the treatment groups. No new safety signals were seen.

CONCLUSION

This analysis confirms the IDFS benefit from adding pertuzumab to standard adjuvant therapy for patients with node-positive HER2-positive early BC. Longer follow-up is needed to fully assess OS benefit.

Appraising the quality of meta-analysis for breast cancer treatment in the adjuvant setting: A systematic review

INTRODUCTION

Breast cancer is the tumor with highest incidence in women worldwide and adjuvant treatment is extremely important to achieve disease control. Given the relevance of systematic reviews, their rigor should be warranted to avoid biased conclusions. Our objective was to investigate the methodological quality of meta-analysis of early breast cancer adjuvant treatment.

MATERIAL AND METHODS

Comprehensive searches were performed using electronic databases from 1/1/2007 to 11/12/2018. All studies identified as a systematic review with meta-analysis investigating the efficacy of breast cancer adjuvant treatments were included. Two reviewers independently assessed titles and abstracts, then full-texts for eligibility. Quality was assessed using the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) version 2 tool.

RESULTS

Of 950 citations retrieved, 66 studies (7.0%) were deemed eligible. Methodological quality was highly variable, median AMSTAR score 8.5 (IQR 7-9.5) and range 0-16. There was a weak positive correlation between journal impact factor and AMSTAR score (r = 0.17) and citation rate and AMSTAR score (r = 0.16). Cochrane Systematic Reviews were of higher quality than reviews from other journals. Overall confidence was critically low for 61 (92.4%) studies, and the least well-reported domains were the statement of conflict of interest and funding source for the included studies (4.6%), the report of a pre-defined study protocol (15.2%), and the description of details of excluded studies (6.1%).

CONCLUSIONS

Our findings reinforce concerns about the design, conduction and interpretation of meta-analysis in current literature. Methodological quality should be carefully considered and journal editors, decision makers and readers in general, must follow a critical approach to this studies.

Clinical predictors of cardiac toxicity in HER2-positive early breast cancer patients treated with adjuvant s.c. versus i.v. trastuzumab

Background

Few data are available about real-life cardiotoxicity associated with s.c. versus i.v. trastuzumab treatment of early-stage, HER2-positive breast cancer, and little is known about its predisposing factors.

Patients and methods

We retrospectively reviewed data of 363 adult patients treated with adjuvant trastuzumab for HER2-positive breast cancer. Univariate statistical analysis was performed, and a multivariable logistic model was developed to identify independent risk factors of cardiac toxicity.

Results

Within 5 years, the overall incidence of events meeting our criteria was 11.8%, and an early discontinuation of trastuzumab was recorded in 20 patients (5.5%). No cases of congestive heart failure occurred, neither multiple events per patient were observed. A total of 184 patients received i.v. and 179 received s.c. trastuzumab. Compared with the s.c. formulation, a higher cardiotoxicity rate for the i.v. administration (15.2% vs 8.4%) was found, and particularly in those patients with cardiovascular risk factors (19.3% vs 8.7%), at the univariate and multivariate analyses. Although more patients with prior anthracycline-based chemotherapy experienced cardiac events, the association of this therapy with cardiac events was not significant. The incidence of cardiac events was not influenced by anthropometric data (e.g. body mass index) or a diagnosis of diabetes mellitus. 5-year event-free survival was 91.7% in the overall population; event-free survival rates were similar between the s.c. and the i.v. groups.

Conclusion

Our study shows a more favorable safety profile of s.c. versus i.v trastuzumab administration. The use of s.c. trastuzumab could be advisable in at-risk patients.

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Few data are available about cardiotoxicity associated with s.c. versus i.v. trastuzumab and its predisposing factors.

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Our study shows a more favorable safety profile of s.c. versus i.v trastuzumab administration.

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Thus, the use of s.c. trastuzumab could be advisable in at risk patients.

Do all patients with HER2 positive breast cancer require one year of adjuvant trastuzumab? A systematic review and meta-analysis

One year of adjuvant trastuzumab is considered the standard treatment for patients with HER2 positive breast cancer. However, a shorter duration of trastuzumab may be associated with reduced costs and side effects. Results from randomized trials with diverse non-inferiority margins comparing one year to a shorter duration of adjuvant trastuzumab are not consistent and have not been systematically reviewed using a non-inferiority meta-analysis approach. We conducted a systematic review and meta-analysis of randomized trials to assess whether a shorter duration of adjuvant trastuzumab was non-inferior to one year of treatment or not. The non-inferiority margin for the meta-analysis was pre-defined as the median of the margins of all the trials included. Data of 11,376 patients from 5 trials were analyzed. Non-inferiority margins in included studies varied from 1.15 to 1.53 with median of 1.29 for HR of DFS. A shorter duration of trastuzumab was non-inferior to one year of therapy for DFS (HR 1.13, 95%CI 1.03-1.24) but inconclusive for OS (HR 1.14, 95%CI 1.00-1.30). In a subgroup analysis for DFS outcome, shorter therapy was non-inferior in patients with ER positive disease (HR 1.10, 95%CI 0.95-1.28) and those with sequential therapy (HR 0.97, 95%CI 0.75-1.27) and when the duration of treatment was 6 months (HR 1.09, 95%CI 0.98-1.22). Although a shorter duration of adjuvant trastuzumab was non-inferior to one year of therapy for DFS in patients with HER2 positive breast cancer based on our HR margin of 1.29, any benefit of a shorter duration comes at a loss of efficacy with an increase in absolute risk up to 3.9% for 5 year DFS. Whether the potential increased risk is clinically acceptable for the benefits of a shorter duration remains debatable.

Road Map to Safe and Well-Designed De-escalation Trials of Systemic Adjuvant Therapy for Solid Tumors

An important challenge in the field of cancer is finding the balance between delivering effective treatments and avoiding adverse effects and financial toxicity caused by innovative, yet expensive, drugs. To address this, several treatment de-escalation trials have been conducted, but only a few of these have provided clear answers. A few trials had poor accrual or had design flaws that led to conflicting results. Members of the Breast International Group (BIG) and North American Breast Cancer Group (NABCG) believe the way forward is to understand the lessons from these trials and listen more carefully to what truly matters to our patients. We reviewed several adjuvant trials of different cancer types and developed a road map for improving the design and implementation of future de-escalation trials. The road map incorporates patients' insights obtained through focused group discussions across the BIG-NABCG networks. Considerations for the development of de-escalation trials for systemic adjuvant treatment, including noninferiority trial design, choice of end points, and prioritization of a patient's perspectives, are presented in this consensus article.

Optimum duration of adjuvant trastuzumab in treatment of human epidermal growth factor receptor-2 positive early breast cancer: protocol for a network meta-analysis of randomised controlled trials

INTRODUCTION

Controversy regarding optimum duration of trastuzumab treatment remains in patients with human epidermal growth factor receptor-2 (HER2) positive early breast cancer. The objective of applying network meta-analysis (NMA) is to integrate existing evidence based on direct and indirect comparisons of efficacy and safety, and then to determine the duration of trastuzumab treatments with the greatest impact on therapeutic outcomes in HER2-positive early breast cancers.

METHODS AND ANALYSIS

Electronic searching of trastuzumab treatments for early breast cancer by titles and abstracts will be conducted for the period from inception to 16 June 2019 in PubMed, Cochrane Library, Embase and ClinicalTrils.gov, as well as the annual meetings of San Antonio Breast Cancer Symposium (SABCS), European Society of Medical Oncology (ESMO) and American Society of Clinical Oncology (ASCO) online archives. The outcomes of interest are overall survival, disease-free survival, acceptability, cardiotoxicities and grade 3 to 4 non-haematological toxicities. Two independent reviewers will screen and extract eligible data based on the inclusion and exclusion criteria, and then assess the risk of bias and evidence quality of individual studies using Cochrane Collaboration's tool and Grades of Recommendation, Assessment, Development and Evaluation (GRADE). The heterogeneity, transitivity and inconsistency of NMA will be evaluated. In addition, we will perform subgroup and sensitivity analyses to assess the robustness and reliability of findings in our NMA.

ETHICS AND DISSEMINATION

Ethics approval is not required for our NMA. Findings from our NMA will be submitted as peer-reviewed journal manuscripts and international conference reports.

TRIAL REGISTRATION NUMBER

CRD42019139109.

Evaluation of 1-Year vs Shorter Durations of Adjuvant Trastuzumab Among Patients With Early Breast Cancer: An Individual Participant Data and Trial-Level Meta-analysis

IMPORTANCE

The optimum duration of adjuvant trastuzumab among patients with early breast cancer is uncertain but of great therapeutic relevance.

OBJECTIVE

To compare shorter durations with 1 year of adjuvant trastuzumab for patients with early breast cancer.

DATA SOURCES

PubMed, Embase, Cochrane Central Register of Clinical Trials, and conference proceedings were searched from January 1, 2005, to June 30, 2019, for relevant randomized clinical trials (RCTs).

STUDY SELECTION

To be eligible, the trial had to be randomized, compare a shorter duration with 1 year of trastuzumab as adjuvant treatment, and include patients with early breast cancer.

DATA EXTRACTION AND SYNTHESIS

Individual patient data for disease-free survival (DFS) and overall survival (OS) were extracted from published survival curves of included RCTs; DFS and OS curves for each trial and the combined population were reconstructed. The DFS and OS hazard ratios (HRs) were estimated from the reconstructed survival curves as well as published estimates. The HR for DFS was used to test noninferiority using the median noninferiority margin of eligible RCTs. This study followed Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline.

MAIN OUTCOMES AND MEASURES

The primary outcome was DFS; OS and cardiac toxic effects were secondary outcomes.

RESULTS

There were 6 eligible RCTs with a median DFS noninferiority margin of 1.3 (range, 1.15-1.53), 5 of which had extractable individual patient data for 11 376 patients, 1659 DFS events, and 871 deaths. For shorter duration vs 1 year of trastuzumab, the 5-year DFS was 85.42% (95% CI, 84.41%-86.38%) vs 87.12% (95% CI, 86.15%-88.02%) (HR, 1.14; 95% CI, 1.03-1.25, 1-sided P for noninferiority = .004), and OS was 92.39% (95% CI, 91.61%-93.10%) vs 93.46% (95% CI, 92.73%-94.13%) (HR, 1.17; 95% CI, 1.02-1.33). Using trial-level published estimates from 6 RCTs, including 11 603 patients, 1760 DFS events, and 930 deaths, the HR for DFS was 1.15 (95% CI, 1.04-1.26; 1-sided P for noninferiority = .002) and, for OS, 1.17 (95% CI, 1.03-1.33). There was significantly less risk of congestive heart failure with shorter-duration trastuzumab (relative risk, 0.53; 95% CI, 0.38-0.74).

CONCLUSIONS AND RELEVANCE

In this study, a shorter duration of adjuvant trastuzumab was noninferior to its 1-year administration and resulted in lower rates of cardiac toxic effects. These results suggest that a shorter duration may be the preferred option for patients with low-risk disease or a predisposition to cardiac toxic effects.

What Is the Real Impact of Estrogen Receptor Status on the Prognosis and Treatment of HER2-Positive Early Breast Cancer?

HER2+ early breast cancer is a heterogeneous disease, comprising all the intrinsic breast cancer subtypes. The only biomarker available nowadays for anti-HER2 treatment selection is HER2 status itself, but estrogen receptor (ER) status is emerging as a robust predictive marker within HER2+ disease. In this Perspective, we discuss the biological and clinical differences between patients with HER2+/ER-positive (ER+) disease versus those with HER2+/ER-negative (ER-neg) tumors, namely, short-term and long-term (>5 years after diagnosis) prognosis, response to neoadjuvant treatment and benefit from adjuvant anti-HER2-targeted therapies. We also address other possible biomarkers to be used for patient selection in future clinical trials, such as gene signatures, PAM50 subtypes, tumor-infiltrating lymphocytes, PIK3CA mutations, and changes in Ki67 score during treatment and discuss their limitations. Finally, we suggest new clinical trial designs that can have an impact on clinical practice, aiming to test treatment deescalation separately for patients with HER2+/ER+ and HER2+/ER-neg tumors. We also propose an integrated classification of HER2+ disease, comprising DNA, RNA, protein expression, and microenvironment characteristics, in order to identify those tumors that are truly "HER2-addicted" and may benefit the most from anti-HER2 treatment.

Systemic treatment of patients with early breast cancer: recent updates and state of the art

This review is focused on trials generating results that potentially impacted clinical practice since the 2017 St. Gallen Consensus; the most impactful trial was KATHERINE, which revealed a 11.3% absolute iDFS improvement with T-DM1 (compared to trastuzumab) in HER2-positive breast cancer patients who presented invasive residual disease following neoadjuvant treatment. These results, if reinforced by a subsequent overall survival benefit, will consolidate neoadjuvant treatment as the standard-of-care for most HER2-positive breast cancer patients. The addition of pertuzumab to adjuvant trastuzumab (APHINITY) or extending anti-HER2 therapy with 1 year of neratinib (ExteNET) also improved outcomes, but in a more modest way. In triple-negative early breast cancer patients presenting invasive residual disease after neoadjuvant chemotherapy, the CREATE-X trial demonstrated the benefit of post-neoadjuvant capecitabine. In patients with luminal tumours, updated results of the SOFT/TEXT trials confirmed the benefit of aromatase inhibitors plus ovarian suppression in high-risk premenopausal patients, and the 12-year results of the BIG1-98 trial demonstrated a sustained trend in favour of letrozole compared to tamoxifen in the adjuvant treatment of postmenopausal patients. The TAILOR-X study showed that, overall, patients with an intermediate recurrence risk score (11-25) in the OncotypeDX 21-gene assay did not benefit from adjuvant chemotherapy. A meta-analysis performed by the EBCTCG demonstrated that extended adjuvant aromatase inhibitors modestly reduced breast cancer recurrence risks, with a more pronounced benefit in patients previously treated with tamoxifen. Finally, an EBCTCG meta-analysis including patients with all breast cancer subtypes showed that dose-dense chemotherapy improved survival when compared to conventionally-timed chemotherapy.

Six Months vs. 12 Months of Adjuvant Trastuzumab Among Women With HER2-Positive Early-Stage Breast Cancer: A Meta-Analysis of Randomized Controlled Trials

Purpose: Both 12 and 6 months of trastuzumab in combination with chemotherapy are effective for HER2+ early-stage breast cancer. This meta-analysis was performed to assess the effectiveness and the toxicity of the two durations. Methods and Materials: We acquired relevant randomized controlled trials (RCTs) from PubMed, the Cochrane Library, ScienceDirect, EMBASE, Ovid MEDLINE, Web of Science, Scopus, and Google Scholar. Our endpoints included disease-free survival (DFS), overall survival (OS), number of recurrences, mortality and early stopping of trastuzumab, and adverse events (AEs). Results: We included five good-quality studies. Both durations of trastuzumab were effective among women with HER2+ early-stage breast cancer, but 12 months of trastuzumab appeared to have better DFS [hazard ratio (HR) = 1.10, 95% confidence interval (CI): 0.99-1.23, P = 0.09] and better OS than 6 months of trastuzumab (HR = 1.14, 95% CI: 0.99-1.32, P = 0.07). However, the 12 month group had more AEs, especially cardiac events [risk ratio (RR) = 0.66, 95% CI: 0.56-0.77, P < 0.00001]. In our sub-analyses, the 12 months duration had better DFS among patients using trastuzumab concurrently than the 6 months duration (HR = 1.23, 95% CI: 1.06-1.44, P = 0.006). Additionally, the 12 months duration had superior OS in women with ER-negative breast cancer (HR = 1.51, 95% CI: 1.10-2.08, P = 0.01) and patients treated with trastuzumab concurrently than the 6 months duration (HR = 1.61, 95% CI: 1.13-2.29, P = 0.008). Conclusions: Twelve months was the standard duration of adjuvant trastuzumab among patients with HER2+ early-stage breast cancer, with a tendency toward superior survival. However, patients in the 12 month group had more significant cardiac toxicity than those in the 6 month group.

Biological Characteristics and Long-term Outcomes in Node-negative Breast Cancer

BACKGROUND

Because the risk of relapse of node-negative breast cancer (BC) is varying, we evaluated the prognosis of patients with this disease and the factors associated with increased risk of relapse.

PATIENTS AND METHODS

The clinical charts of patients with BC with evidence of negative nodes and with a potential ≥ 5-year follow-up were retrospectively reviewed.

RESULTS

We analyzed 1276 patients. Over a median follow-up of 71.6 months (range, 1-227.2 months), we observed 159 events of relapse or death. The median RFS was 170 months. The median overall survival (OS) was 192 months. At univariate analysis, older age, negative hormonal receptors, larger tumor size and higher proliferation index (Ki67) were associated with worse recurrence-free survival (RFS) and OS (P < .05); higher grading was associated with worse RFS (P = .01). At multivariate analysis for RFS, age, Ki67 and tumor size confirmed their independent prognostic role. At multivariate analysis for OS, age and positive hormonal receptors showed an independent prognostic role. We observed no differences in prognosis between human epidermal growth factor receptor 2 (HER2) positive and triple-negative (TN) BC, but TNBC showed a worse OS compared with luminal-like BC.

CONCLUSIONS

In node-negative BC, age, hormone receptor status, tumor size and Ki67 were prognostic factors. The TNBC subtype was not associated with poorer prognosis compared with the HER2-positive subtype, but showed a worse OS compared with luminal-like BC.

Prognostic and Predictive Impact of Beta-2 Adrenergic Receptor Expression in HER2-Positive Breast Cancer

BACKGROUND

Beta-2 adrenergic receptor (ADRB2) mediates proliferation and treatment resistance in preclinical models of human epidermal growth factor receptor 2 positive (HER2+) breast cancer. We evaluated ADRB2 gene expression as a prognostic and predictive biomarker in patients with HER2+ early breast cancer.

METHODS

ADRB2 expression was retrieved from HER2+ patients enrolled in the FinHer study (N = 202), and 2 public datasets containing data from patients with HER2+ early breast cancer: one including patients who did not receive systemic treatment (disease-free survival [DFS] dataset; n = 175) and another including patients who received neoadjuvant treatment (pathologic complete response [pCR] dataset; n = 207). Survival was estimated with Kaplan-Meier method and Cox regression was used for uni-multivariate analyses. ADRB2 expression was correlated with several gene signatures.

RESULTS

ADRB2 high expression was associated with improved DFS rates in HER2+ patients (hazard ratio [HR] 0.52; 95% confidence interval [CI] 0.32-0.84; P = .0068). No association between ADRB2 expression and pCR was observed (odds ratio 1.14; 95% CI, 0.63-2.10; P = .67). No association between ADRB2 and relapse-free survival (RFS) was observed in HER2+ patients enrolled in the FinHer study (HR 0.93; 95% CI, 0.69-1.25; P = .61). ADRB2 was associated with a low expression of angiogenesis-related (vascular endothelial growth factor -0.38, P < .001) and proliferation-related (aurora kinase A -0.36, P < .001; genomic grade index -0.028, P < .001; signal transducers and activators of transcription -0.17, P < .001) genes; and a high expression of immune-related genes (Perez +0.45, P < .001; STAT1 +0.28, P < .001; immune response gene expression module +0.29, P < .001).

CONCLUSIONS

Opposing our initial hypothesis, a high ADRB2 expression may be a favorable prognostic factor in patients with HER2+ early breast cancer. This association appears to be mediated by antiproliferative, antiangiogenic, and immunogenic effects of ADRB2.

Trastuzumab in the Treatment of Pregnant Breast Cancer Patients - an Overview of the Literature

Breast cancer is one of the most common malignancies which appear during pregnancy. Since women are increasingly not giving birth until they are at a more advanced age, it can be assumed that the incidence of pregnancy-related breast cancers will continue to increase in the future. Because of pregnancy-induced changes and conservative diagnosis, these carcinomas are frequently not detected until they are at an advanced stage and thus generally require systemic adjuvant therapy. The available data on optimal chemotherapeutic management are limited. Particularly for the use of the target agent trastuzumab which could crucially contribute to improving the prognosis in the therapy of HER2-overexpressing breast cancer in non-pregnant women, there is a lack of definitive information regarding the profile of action and safety in pregnancy as well as with regard to any long-term effects on the child. Thirty-eight pregnancies on trastuzumab for the treatment of breast cancer were able to be analysed in the literature currently available. Information can be gained from this and conclusions can be drawn which can individualise and decisively improve therapeutic options in the future for the pregnant breast cancer patient.

De-escalated neoadjuvant therapy with nanoparticle albumin-bound paclitaxel and trastuzumab for low-risk pure HER2 breast cancer

PURPOSE

Neoadjuvant trastuzumab combined with anthracycline and taxane is now considered a standard regimen for human epidermal growth factor receptor 2 (HER2)-positive breast cancer. A less toxic, non-anthracycline regimen has been considered as a treatment option for patients with node-negative small tumors. Estrogen receptor-negative and HER2-positive (pure HER2) tumors are more likely to achieve a pathological complete response (pCR). This study evaluates the activity and safety of neoadjuvant nanoparticle albumin-bound paclitaxel (nab-PTX) plus trastuzumab for pure HER2 breast cancer in patients with low risk of relapse.

METHODS

We treated patients with tumors measuring ≤ 3 cm, node-negative, pure HER2 breast cancer using neoadjuvant nab-PTX 260 mg/m2 with trastuzumab every 3 weeks for four cycles. The primary endpoint was the pCR rate. The secondary endpoints included the clinical response rate, disease-free survival, pathologic response rate (defined as pCR or minimal residual invasive disease only in the breast), breast-conserving surgery conversion rate, safety, and disease-free survival. Depending on the pathological findings of surgical specimens, the administration of adjuvant anthracycline could be omitted.

RESULTS

Eighteen patients were enrolled. No patient required dose delays or reductions; none showed disease progression, and all patients underwent surgery as scheduled. Of the 18 patients, 66.7% achieved pCR, and the adjuvant anthracycline regimen was omitted for all patients. The incidence of severe adverse events was quite low.

CONCLUSION

This less toxic, anthracycline-free regimen appears to be a significantly effective neoadjuvant therapy for patients with pure HER2 breast cancer at low relapse risk.

Risk Factors Associated with Trastuzumab-induced Cardiotoxicity in Patients with Human Epidermal Growth Factor Receptor 2-positive Breast Cancer

Context:

Although trastuzumab is a highly effective and selective targeted therapy for human epidermal growth factor receptor 2 (HER2)-positive breast cancer, the drug-induced cardiotoxicity may confine its usefulness in patients.

Aim:

To explore risk factors associated with the development of cardiotoxicity in patients with HER2-positive breast cancer.

Settings and Design:

A retrospective review of medical records and chart review for all patients with breast cancer treated with trastuzumab was conducted at King Abdulaziz Medical City and King Abdullah Specialized Children Hospital in Riyadh, Kingdom of Saudi Arabia, between October 2015 and February 2018. Patients with declined left ventricular ejection fraction, either with or without cardiac symptoms, were recognized as those with cardiotoxicity due to trastuzumab administration.

Results:

A total of 146 patients were included in the study with an average age of 52.7 (standard deviation = 12.2) years. Thirty-two (21.9%) patients developed cardiotoxicity. However, only 24 (16.4%) were symptomatic with an apparent heart failure but it did not necessitate interruption of trastuzumab therapy. The majority of patients had prior underlying cardiovascular diseases. This study identified unilateral tumor site (62.5%), breast surgery (37.5%), and concomitant taxane chemotherapy (62.5%) as the main risk factors associated with significant increase in cardiotoxicity in patients with breast cancer (with P values of 0.0269, 0.0482, and 0.0225, respectively).

Conclusion:

The majority of patients (more than 90%) developed cardiotoxicity after completion of chemotherapy. However, recruiting a larger sample size should be warranted to confirm or negate these findings.