Patterns of Care and Clinical Outcomes of First-Line Trastuzumab-Based Therapy in HER2-Positive Metastatic Breast Cancer Patients Relapsing After (Neo)Adjuvant Trastuzumab: An Italian Multicenter Retrospective Cohort Study

Trastuzumab Resistance in Patients With HER2-Positive Advanced Breast Cancer: Results From the SONABRE Registry

BACKGROUND

This study aims to explore whether first-line pertuzumab use modifies the effect of prior use of (neo-) adjuvant trastuzumab on the PFS of first-line HER2-targeted therapy in patients with human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer (ABC).

METHODS

Patients diagnosed with HER2-positive ABC in 2008 to 2018 in 9 Dutch hospitals were derived from the SONABRE Registry (NCT03577197). Patients diagnosed with de novo metastatic breast cancer were excluded. Patients receiving first-line trastuzumab-based therapy for ABC were selected and divided into trastuzumab naïve (n = 113) and trastuzumab pretreated (n = 112). Progression-free survival (PFS) was compared using multivariable Cox proportional hazard models. The interaction effect of first-line pertuzumab was tested using the likelihood-ratio test.

RESULTS

The median follow-up time was 47 months (95% confidence interval [CI]: 42-52). When comparing trastuzumab pretreated with trastuzumab naïve patients, the hazard ratio for first-line progression was 2.07 (CI:1.47-2.92). For trastuzumab pretreated patients who received first-line trastuzumab without pertuzumab, the hazard ratio for progression was 2.60 (95% CI:1.72-3.93), whereas for those who received first-line trastuzumab with pertuzumab the hazard ratio was 1.43 (95% CI: 0.81-2.52) (P interaction = .10).

CONCLUSIONS

Prior use of trastuzumab as (neo-)adjuvant treatment had a negative impact on PFS of first-line HER2-targeted therapy outcomes. Adding pertuzumab to first-line trastuzumab-based therapy decreased the negative impact of prior (neo-)adjuvant trastuzumab use on first-line PFS. Further studies are needed to assess the effect of prior (neo-)adjuvant pertuzumab use on the outcomes of first-line pertuzumab-based therapy.

Real-World Impact of Adjuvant Anti-HER2 Treatment on Characteristics and Outcomes of Women With HER2-Positive Metastatic Breast Cancer in the ESME Program

BACKGROUND

Although adjuvant cancer treatments increase cure rates, they may induce clonal selection and tumor resistance. Information still lacks as whether (neo)adjuvant anti-HER2 treatments impact the patterns of recurrence and outcomes of HER2-positive (HER2+) metastatic breast cancer (MBC). We aimed to assess this in the large multicenter ESME real-world database.

PATIENTS AND METHODS

We examined the characteristics and outcomes (overall survival (OS) and progression-free survival under first-line treatment (PFS1)) of HER2+ patients with MBC from the French ESME program with recurrent disease, as a function of the previous receipt of adjuvant trastuzumab. Multivariable analyses used Cox models adjusted for baseline demographic, prognostic factors, adjuvant treatment received, and disease-free interval.

RESULTS

Two thousand one hundred and forty-three patients who entered the ESME cohort between 2008 and 2017 had a recurrent HER2+ MBC. Among them, 56% had received (neo)adjuvant trastuzumab and 2.5% another anti-HER2 in this setting. Patients pre-exposed to trastuzumab were younger, had a lower disease-free interval, more HR-negative disease and more metastatic sites. While the crude median OS appeared inferior in patients exposed to adjuvant trastuzumab, as compared to those who did not (37.2 (95%CI 34.4-40.3) versus 53.5 months (95% CI: 47.6-60.1)), this difference disappeared in the multivariable model (HR = 1.05, 95%CI 0.91-1.22). The same figures were observed for PFS1.

CONCLUSIONS

Among patients with relapsed HER2+ MBC, the receipt of adjuvant trastuzumab did not independently predict for worse outcomes when adjusted to other prognostic factors.

Association of Endocrine Therapy for HR+/ERBB2+ Metastatic Breast Cancer With Survival Outcomes

IMPORTANCE

Evidence suggests that patients with human epidermal growth factor receptor 2-positive (ERBB2+ [formerly HER2+]) metastatic breast cancer (MBC) have different clinical characteristics and outcomes according to their hormone receptor (HR) status. The place of endocrine therapy (ET) for patients with HR+/ERBB2+ is still not clearly defined in this setting.

OBJECTIVE

To evaluate the association of HR status and first-line inclusion of ET with outcomes among patients with ERBB2+ MBC.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was an analysis of clinical data from the French clinical Epidemiological Strategy and Medical Economics (ESME) cohort, including patients with MBC who started treatment between 2008 and 2017. The last date of follow-up was June 18, 2020. Data were analyzed from May 2021 to May 2022.

EXPOSURES

Patients were treated with first-line ERBB2-targeted therapy and either chemotherapy (CT) with or without ET or ET alone. For the study of the association of maintenance ET with outcomes, we included patients treated with first-line ERBB2-targeted therapy with CT and with or without maintenance ET.

MAIN OUTCOMES AND MEASURES

Median overall survival (OS) and median first-line progression-free survival (PFS) were reported using the Kaplan-Meier method. Cox proportional hazards models and a propensity score were constructed to report and adjust for prognostic factors. Multivariable analysis included age at MBC, time to MBC, number of metastatic sites, type of metastases, and Eastern Cooperative Oncology Group performance status.

RESULTS

Among 4145 women with ERBB2+ MBC, 2696 patients had HR+ (median [IQR] age, 58.0 [47.0-67.0] years) and 1449 patients had HR- (56.0 [47.0-64.0] years) tumors. The median OS for patients with HR+ vs HR- tumors was 55.9 months (95% CI, 53.7-59.4 months) vs 42.0 months (95% CI, 38.8-45.2 months), confirmed in multivariable analysis (hazard ratio, 1.40; 95% CI, 1.26-1.56; P < .001). The median PFS for patients with HR+ vs HR- tumors was 12.2 months (95% CI, 11.5-12.9 months) vs 9.8 months (95% CI, 9.2-11.0 months; P = .01), and the HR was 1.15 (95% CI, 1.06-1.26; P < .001). In multivariable analysis, no significant difference was found in OS or PFS for 1520 patients treated with ERBB2-targeted therapy with CT and with or without ET vs 203 patients receiving ERBB2-targeted therapy with ET, regardless of type of ERBB2-targeted therapy (trastuzumab or trastuzumab with pertuzumab). This result was confirmed by matching patients using a propensity score. Using the time-dependent ET variable among patients with ERBB2-targeted therapy with CT, those with maintenance ET had significantly better PFS (hazard ratio, 0.70; 95% CI, 0.60-0.82; P < .001) and OS (hazard ratio, 0.47; 95% CI, 0.39-0.57; P < .001).

CONCLUSIONS AND RELEVANCE

These results suggest that ET-containing first-line regimens may be associated with benefits among a subgroup of patients with HR+/ERBB2+ MBC.

T-DM1 after Pertuzumab plus Trastuzumab: Treatment Sequence-Induced Selection Bias in HER2-Positive Metastatic Breast Cancer

Real-world studies have suggested decreased trastuzumab emtansine (T-DM1) effectiveness in patients with metastatic breast cancer (mBC) who received prior trastuzumab plus pertuzumab (H + P). However, these studies may have been biased toward pertuzumab-experienced patients with more aggressive disease. Using an electronic health record-derived database, patients diagnosed with mBC on/after 1 January 2011 who initiated T-DM1 in any treatment line (primary cohort) or who initiated second-line T-DM1 following first-line H ± P (secondary cohort) from 22 February 2013 to 31 December 2019 were included. The primary outcome was time from index date to next treatment or death (TTNT). In the primary cohort (n = 757), the percentage of patients with prior P increased from 37% to 73% across the study period, while population characteristics and treatment effectiveness measures were generally stable. Among P-experienced patients from the secondary cohort (n = 246), median time from mBC diagnosis to T-DM1 initiation increased from 10 to 14 months (2013-2019), and median TTNT increased from 4.4 to 10.2 months (2013-2018). Over time, prior H + P prevalence significantly increased with no observable impact on T-DM1 effectiveness. Drug approval timing should be considered when assessing treatment effectiveness within a sequence.

Prognostic role of distant disease-free interval from completion of adjuvant trastuzumab in HER2-positive early breast cancer: analysis from the ALTTO (BIG 2-06) trial

Background

In HER2-positive breast cancer, time elapsed between completion of (neo)adjuvant trastuzumab and diagnosis of metastatic disease (‘trastuzumab-free interval’, TFI) is crucial to choose the optimal first-line treatment. Nevertheless, there is no clear evidence to support its possible prognostic role.

Methods

In the Adjuvant Lapatinib and/or Trastuzumab Treatment Optimisation (ALTTO) trial, patients with HER2-positive early breast cancer were randomised to 1 year of either trastuzumab alone, lapatinib alone, their sequence or their combination. This exploratory analysis included only patients in the trastuzumab alone or trastuzumab plus lapatinib arms who developed a distant disease-free survival (DDFS) event. Overall survival (OS) was defined as time between date of DDFS event and death; age at diagnosis, tumour size and hormone receptor status were the variables included in the multivariate models.

Results

Out of 8381 patients included in ALTTO, 404 patients in the trastuzumab alone and trastuzumab plus lapatinib arms developed a DDFS event, of which 201 occurred <12 months (group A) and 203 >12 months (group B) after completion of adjuvant trastuzumab. No significant difference in location of first DDFS event was observed (p=0.073); a numerically higher number of patients in group A than in group B developed brain metastasis (26% vs 15%). Choice of first-line therapy differed between the two groups (p=0.022): in group A, more patients received lapatinib (25% vs 11%) and less pertuzumab (8% vs 17%). Median OS was 29.3 and 18.4 months in groups B and A, respectively (adjusted HR 0.69; 95% CI 0.54–0.89; p=0.004). The longer OS for patients in group B was observed across the analysed subgroups without interaction according to hormone receptor status (p=0.814) nor type of administered adjuvant anti-HER2 treatment (p=0.233).

Conclusions

TFI has prognostic value in patients with HER2-positive early breast cancer treated with adjuvant trastuzumab-based therapy. TFI is a valid tool to better individualise clinical recommendations and to design future first-line treatment trials for metastatic patients.

Adjuvant endocrine therapy in HER2-positive breast cancer patients: systematic review and meta-analysis

Background

Approximately 50% of human epidermal growth factor receptor 2 (HER2)-positive breast cancer lesions express hormone receptors. These tumors present a unique therapeutic challenge, and the optimal endocrine therapeutic approach remains controversial. We aimed to study the optimal adjuvant endocrine therapy in this setting, to better establish the basis for clinical recommendations in HER2-positive disease.

Methods

We conducted a literature search up to May 2020, in which we identified randomized controlled trials (RCTs) that investigated the efficacy of various adjuvant hormonal therapies among premenopausal and postmenopausal patients with hormone receptor (HR)-positive, HER2-positive early breast cancer. Disease-free survival (DFS) was calculated with the random effect model and hazard ratios (HRs) with 95% confidence intervals (CI).

Results

Six RCTs (N = 5390 patients) were included in the final analysis. There was no significant difference in DFS between adjuvant treatment with aromatase inhibitors and tamoxifen (HR 0.99, 95% CI 0.68-1.44, P = 0.96). Furthermore, after omitting the ALTTO trial, as it did not randomize patients to hormonal therapy, no significant difference was observed between the two protocols (HR 1.06, 95% CI 0.65-1.73, P = 0.81).

Conclusion

Our study demonstrates similar DFS with tamoxifen and aromatase inhibitors as adjuvant endocrine treatment in HER2-positive HR-positive early-stage breast cancer patients. Future larger prospective studies focusing on the various contemporary endocrine regimens are warranted to validate our findings.

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Optimal adjuvant endocrine therapy for early-stage breast cancer with co-expression of HER2 and hr is unclear.

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Our analysis demonstrated no difference in disease-free survival between selected endocrine regimens among these patients.

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Study strength includes longer follow-up, premenopausal patients and current HER2 regimens and combinations.

Clinical outcomes of patients with breast cancer relapsing after (neo)adjuvant trastuzumab and receiving trastuzumab rechallenge or lapatinib-based therapy: a multicentre retrospective cohort study

Background

In the prepertuzumab era, we evaluated the clinical outcomes of patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer who underwent first-line trastuzumab-based or lapatinib-based therapy according to prior exposure to (neo)adjuvant trastuzumab.

Materials and methods

In this multicentre retrospective cohort study conducted in 14 Italian centres of the Gruppo Italiano Mammella, consecutive patients undergoing first-line trastuzumab or lapatinib-based therapy were included. Analyses were performed according to the type of first-line therapy for metastatic disease (trastuzumab or lapatinib). Dichotomous clinical outcomes were analysed using logistic regression and time-to-event outcomes using Cox proportional hazard models controlling for relevant demographic, clinicopathological and therapy characteristics.

Results

Out of 450 patients included in the study, 416 (92%) received trastuzumab and 34 (7.5%) lapatinib. As compared with the trastuzumab cohort, more patients in the lapatinib cohort had a trastuzumab-free interval <1 month (37% vs 13.9%; p=0.017) and brain metastasis as first site of relapse (38.2% vs 9.4%; p<0.001). Among the 128 patients who relapsed after prior (neo)adjuvant trastuzumab, 101 (78.9%) received first-line trastuzumab and 27 (21.1%) first-line lapatinib. The following outcomes were observed with first-line lapatinib or trastuzumab, respectively: overall response rate 45.5% vs 61.3% (p=0.184), clinical benefit rate 68.2% vs 72.5% (p=0.691), median progression-free survival (PFS) 11.4 vs 12.0 months (p=0.814) and median overall survival (OS) 34.7 vs 48.2 months (p=0.722). In patients with brain metastasis as first site of relapse, median PFS was 12.2 vs 9.9 months (p=0.093) and median OS 33.7 vs 28.5 months (p=0.280), respectively.

Conclusions

In patients with HER2-positive breast cancer relapsing after prior (neo)adjuvant trastuzumab, first-line treatment with trastuzumab or lapatinib was not associated with a significant difference in the clinical outcomes. A non-significant trend favouring the use of lapatinib was observed in patients with brain metastasis as the first site of relapse.

Randomized, Phase II Study of Trastuzumab Beyond Progression in Patients With HER2-Positive Advanced Gastric or Gastroesophageal Junction Cancer: WJOG7112G (T-ACT Study)

PURPOSE

This study evaluated the continuous use of trastuzumab beyond progression (TBP) in human epidermal growth factor receptor 2 (HER2)-positive advanced gastric or gastroesophageal junction (G/GEJ) cancer.

PATIENTS AND METHODS

Patients with HER2-positive advanced G/GEJ cancer refractory to first-line chemotherapy with trastuzumab in combination with fluoropyrimidine and platinum were eligible. Patients were randomly assigned to the paclitaxel (80 mg/m2, days 1, 8, and 15, every 4 weeks) or paclitaxel with trastuzumab (PT; initially 8 mg/kg followed by 6 mg/kg, every 3 weeks) arms. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), response rate, and safety. Biomarkers such as HER2 expression status in tumor tissue after first-line treatment, HER2 amplification evaluated in serum cell-free DNA, and soluble HER2 levels were analyzed.

RESULTS

Overall, 91 patients were allocated to the paclitaxel (n = 46) and PT (n = 45) arms. The median PFS in the paclitaxel and PT arms was 3.2 and 3.7 months, respectively (hazard ratio [HR], 0.91; 80% CI, 0.67 to 1.22; P = .33), and the median OS in both arms was 10 months (HR, 1.2; 95% CI, 0.75 to 2.0; P = .20). The overall response rates in the paclitaxel and PT arms were 32% and 33%, respectively ( P = 1.00), and safety was comparable between the 2 arms. On exploratory analyses, HER2 positivity of tumor tissues was lost after first-line chemotherapy in 11 (69%) of 16 patients whose tumor tissues were available, and circulating HER2 DNA amplification was detected in 41 (60%) of 68 patients. However, no biomarkers associated with efficacy of TBP were found.

CONCLUSION

The TBP strategy failed to improve PFS in patients with HER2-positive advanced G/GEJ cancer, and no beneficial biomarkers were found.

Pertuzumab and Trastuzumab Emtansine for Human Epidermal Growth Factor Receptor-2-Positive Metastatic Breast Cancer: Contemporary Population-Based Outcomes

Background

Real-world outcomes for patients with human epidermal growth factor receptor-2 (HER2)-positive metastatic breast cancer (MBC) treated with pertuzumab in combination with taxane chemotherapy plus trastuzumab (TaxTP) in the first line setting and trastuzumab emtansine (TE) in any line of treatment are lacking.

Methods

Cohorts of patients treated with (1) TaxTP and (2) TE from January 1, 2013 through December 31, 2016 were retrospectively obtained from a population-based database. Cohorts were described according to age, hormone receptor (HR) status, prior systemic therapies, event-free survival (EFS) defined as time from start of treatment to start of next line of treatment or death, and overall survival (OS).

Results

A total of 122 patients were treated with TaxTP and 104 with TE. In the TaxTP cohort, EFS was significantly longer in the trastuzumab-naïve group compared with the adjuvant trastuzumab group (median EFS = 27.0 vs 12.4 months; P = .002). In the TaxTP cohort, median OS was not reached. In the TE cohort, EFS was significantly longer in the pertuzumab-naïve group compared with pertuzumab-exposed group (median time to treatment failure [TTF] = 18.7 vs 5.5 months; P < .001). Overall survival was also significantly longer in the pertuzumab-naïve group compared with the pertuzumab-exposed group (median OS = 23.2 vs 14.1 months; P = .022). In multivariable analyses, adjuvant trastuzumab and prior pertuzumab exposure in the metastatic setting remained significant predictors of inferior EFS for patients treated with TaxTP and TE, respectively.

Conclusions

New anti-HER2 therapies appear to be clinically relevant in the real-world.

De Novo Versus Recurrent HER2-Positive Metastatic Breast Cancer: Patient Characteristics, Treatment, and Survival from the SystHERs Registry

Background

Limited data exist describing real‐world treatment of de novo and recurrent HER2‐positive metastatic breast cancer (MBC).

Materials and Methods

The Systemic Therapies for HER2‐Positive Metastatic Breast Cancer Study (SystHERs) was a fully enrolled (2012–2016), observational, prospective registry of patients with HER2‐positive MBC. Patients aged ≥18 years and ≤6 months from HER2‐positive MBC diagnosis were treated and assessed per their physician's standard practice. The primary endpoint was to characterize treatment patterns by de novo versus recurrent MBC status, compared descriptively. Secondary endpoints included patient characteristics, progression‐free and overall survival (PFS and OS, by Kaplan‐Meier method; hazard ratio [HR] and 95% confidence interval [CI] by Cox regression), and patient‐reported outcomes.

Results

Among 977 eligible patients, 49.8% (n = 487) had de novo and 50.2% (n = 490) had recurrent disease. A higher proportion of de novo patients had hormone receptor–negative disease (34.9% vs. 24.9%), bone metastasis (57.1% vs. 45.9%), and/or liver metastasis (41.9% vs. 33.1%), and a lower proportion had central nervous system metastasis (4.3% vs. 13.5%). De novo patients received first‐line regimens containing chemotherapy (89.7%), trastuzumab (95.7%), and pertuzumab (77.8%) more commonly than recurrent patients (80.0%, 85.9%, and 68.6%, respectively). De novo patients had longer median PFS (17.7 vs. 11.9 months; HR, 0.69; 95% CI, 0.59–0.80; p < .0001) and OS (not estimable vs. 44.5 months; HR, 0.55; 95% CI, 0.44–0.69; p < .0001).

Conclusion

Patients with de novo versus recurrent HER2‐positive MBC exhibit different disease characteristics and survival durations, suggesting these groups have distinct outcomes. These differences may affect future clinical trial design. Clinical trial identification number. NCT01615068 (http://clinicaltrials.gov).

Implications for Practice

SystHERs was an observational registry of patients with HER2‐positive metastatic breast cancer (MBC), which is a large, modern, real‐world data set for this population and, thereby, provides a unique opportunity to study patients with de novo and recurrent HER2‐positive MBC. In SystHERs, patients with de novo disease had different baseline demographics and disease characteristics, had superior clinical outcomes, and more commonly received first‐line chemotherapy and/or trastuzumab versus those with recurrent disease. Data from this and other studies suggest that de novo and recurrent MBC have distinct outcomes, which may have implications for disease management strategies and future clinical study design.

The SystHERs breast cancer study was a fully enrolled, prospective registry study that explored contemporary treatment patterns and outcomes in patients with HER2‐positive metastatic breast cancer (MBC), resulting in one of the largest real‐world datasets for this population and providing a unique opportunity to assess patients with de novo and recurrent HER2‐positive MBC. This article reports baseline characteristics, treatment patterns, patient‐reported outcomes, and clinical outcomes in these patient subsets.

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.

Relapsed and De Novo Metastatic HER2-positive Breast Cancer Treated With Trastuzumab: Tumor Genotypes and Clinical Measures Associated With Patient Outcome

BACKGROUND

We examined tumor genotype characteristics of human epidermal growth factor receptor 2 (HER2)-positive relapsed (R-) and de novo (dn-) metastatic breast cancer (MBC) in trastuzumab-treated patients who were previously not exposed to this agent.

MATERIALS AND METHODS

We analyzed genotypes obtained upon deep sequencing from 113 HER2-positive primary tumors from 69 patients with R-MBC and 44 patients with dn-MBC.

RESULTS

Mutations were observed in 90 (79.6%) tumors, 56 R-MBC and 34 dn-MBC (median number per tumor: 2; mean: 11.2; range: 0-150). The top mutated gene was TP53 (63.7%) followed by PIK3CA (24.8%) and others that were mostly co-mutated with TP53 (eg, 22 of 28 PIK3CA mutated tumors were co-mutated in TP53, 17 of these were R-MBC [P = .041]). dn-MBC had higher CEN17 average copies (P = .048). Tumor mutational burden inversely correlated with average HER2 copies (rho -0.32; P < .001). In all patients, PIK3CA mutations and higher proliferation rate were independent unfavorable prognosticators. In R-MBC, longer disease-free interval between initial diagnosis and relapse conferred lower risk for time-to-progression (P < .001) and death (P = .009); PIK3CA mutations conferred higher risk for death (P = .035). In dn-MBC, surgical removal of the primary tumor before any other therapy was favorable for time-to-progression (P = .002); higher tumor mutational burden was unfavorable for survival (P = .026).

CONCLUSIONS

Except for the overall unfavorable prognostic effect of PIK3CA mutations in trastuzumab-treated MBC, our exploratory findings indicate that the outcome of patients with R-MBC is related to patient benefit from the preceding adjuvant chemotherapy and provide initial evidence that tumor mutational burden may be related to prognosis in dn-MBC, which is of potential clinical relevance and merits further investigation.

Survival Outcomes of Retreatment with Trastuzumab and Cytotoxic Chemotherapy for HER2-Positive Recurrent Patients With Breast Cancer Who Had Been Treated with Neo/adjuvant Trastuzumab Plus Multidrug Chemotherapy: A Japanese Multicenter Observational Study

Background:

There are little data on the usefulness of trastuzumab (TZM) retreatment as the first-line treatment for patients with HER2 (human epidermal growth factor receptor 2)–positive breast cancer recurrence after perioperative treatment with TZM.

Aim:

To clarify the outcome and safety of TZM retreatment in patients with recurrent HER2-positive breast cancer.

Method:

An observational study was conducted on patients who relapsed after primary systemic therapy with TZM using the central registration system. The primary end point was progression-free survival (PFS). Secondary end points consisted of the response rate, overall survival (OS), and safety.

Result:

In total, 34 patients were registered between July 2009 and June 2012. The median follow-up time was 23.7 months (2-24 months). The 1- and 2-year PFS rates were 46.9% (95% confidence interval (95% CI): 29.2%-62.9%) and 29.8% (95% CI: 15.0%-46.3%), respectively (median 10.6 months). The median PFS time for patients receiving TZM combined with CTx was 13.9 months. The 1-and 2-year OR rates were 93.9 (95% CI: 77.9%-98.4%) and 84.8% (95% CI: 67.4%-93.4%). Trastuzumab-induced grade 3/4 adverse events were not observed.

Conclusions:

This study suggests that the PFS and OS in Japanese patients who relapsed after perioperative TZM therapy improved or were similar to those in previous reports. Differences in patient backgrounds and treatments must be considered when interpreting the results. Trastuzumab should be used combination with CTx and/or HTx for retreatment. Retreatment with TZM is safe.

Trial registration: UMIN000002738.

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.

Outcomes of re-treatment with first-line trastuzumab plus a taxane in HER2 positive metastatic breast cancer patients after (neo)adjuvant trastuzumab: A prospective multicenter study

Trastuzumab is the backbone of HER2-positive early breast cancer (eBC) and metastatic breast cancer (mBC) treatment, but limited data exist as to re-treatment in relapsed patients. In this prospective, single arm, multicenter trial, we assessed efficacy and safety of trastuzumab and taxane combination in Chinese patients with HER2-positive mBC relapsed after prior (neo)adjuvant trastuzumab. Patients with previous (neo)adjuvant trastuzumab treatment for≥9 weeks and a relapse-free interval ≥6 months were assigned to trastuzumab treatment with paclitaxel or docetaxel. The primary endpoint was progression free survival (PFS). Secondary endpoints included overall response rate (ORR), clinical benefit rate (CBR), duration of response (DOR), time to progression (TTP), overall survival (OS) and safety profile. Thirty-two patients were enrolled and treated for a median duration of 33.5 weeks. The median PFS was 9.9 months (95% CI, 6.28 - 13.63 months). The ORR was 81.3% (95% CI, 63.6% - 92.8%) and CBR (CR+PR+SD≥6months) was 81.3% (95% CI, 63.6% - 92.8%). The median DOR was 9.8 months (95% CI, 5.82 - 11.60 months) and median TTP was 9.9 months (95% CI, 6.28-13.63 months). OS median follow-up time was 20.1 months and 25% OS time was 25.5 months. The safety profile was acceptable with common adverse events including leukopenia (59.4%), neutropenia (56.3%), hypoaesthesia (34.4%) and granulocytopenia (31.3%). In conclusion, re-treatment with trastuzumab plus a taxane as first-line therapy is an effective regimen for patients with HER2-positive mBC relapsed after (neo)adjuvant trastuzumab. The safety profile was good and the adverse reactions were tolerable and manageable.

Trastuzumab for metastatic breast cancer: Real world outcomes from an Australian whole-of-population cohort (2001-2016)

PURPOSE

Outcomes for patients treated in clinical trials may not reflect the experience in routine clinical care. We aim to describe the real-world treatment patterns and overall survival (OS) for women receiving trastuzumab for metastatic breast cancer (MBC).

METHODS

Retrospective, whole-of-population cohort study using demographic, dispensing, and medical services data for women in the Herceptin Program for HER2+MBC. We estimated time on trastuzumab and OS from first dispensing of trastuzumab for MBC and rates of cardiac monitoring prior to and during treatment. We stratified outcomes by two groups based on year of initiation: 2001-2008 and 2009-2015. We benchmarked outcomes to two key trastuzumab clinical trials: H0648g (median OS 25 months) and CLEOPATRA (control group median OS 41 months).

RESULTS

Median age of the 5899 women at first trastuzumab dispensing was 57 years (interquartile range [IQR]: 48-66). Median time on trastuzumab increased from 15 months (7-33) in Group One to 18 months (8-42) in Group Two. Median OS increased from 27 months (12-57) in Group One to 38 months (16-83) in Group Two. Rates of cardiac monitoring increased at baseline (52%-76%), and on-treatment (47%-67%), in Group One and Two, respectively.

CONCLUSIONS

OS, duration of trastuzumab, and frequency of cardiac monitoring increased over the study period. Outcomes for trastuzumab in this heterogeneous real world population were reassuringly comparable to those from clinical trials, with the median OS > 3 years in Group Two and 25% of patients living 7 years or longer.

Survival outcomes for Australian women receiving trastuzumab for HER2-positive metastatic breast cancer following (neo)adjuvant trastuzumab: a national population-based observational study (2006-2014)

BACKGROUND

Patients treated with (neo)adjuvant trastuzumab who relapse and receive trastuzumab for metastatic breast cancer (MBC) are a growing population with little outcome data given their exclusion from most clinical trials. We aim to estimate survival outcomes for this trastuzumab 'pre-treated' population.

METHODS

Population-based study of Australian women receiving trastuzumab for HER2-positive MBC between 2006 and 2014, who also received (neo)adjuvant trastuzumab. We used Kaplan-Meier methods to estimate the following: overall survival (OS) from initiation of trastuzumab for MBC; duration of trastuzumab for MBC; and time from last (neo)adjuvant trastuzumab to first trastuzumab for MBC.

RESULTS

Of 3199 patients dispensed trastuzumab for MBC, 634 (20%) had received (neo)adjuvant traztuzumab. Pre-treated patients had a median (interquartile range) OS of 21.8 months (10.9-51.6), trastuzumab duration of 12.8 months (4.7-17.5), and time from last (neo)adjuvant trastuzumab to first trastuzumab for MBC of 15.6 months (6.5-28.6). Median OS for patients initiating trastuzumab <12 months and ⩾12 months from their last (neo)adjuvant trastuzumab were 17.1 months and 24.8 months, respectively.

CONCLUSIONS

Patients starting trastuzumab for MBC following (neo)adjuvant trastuzumab had a median treatment duration of 1 year and OS of almost 2 years. These data help inform clinical practice and service planning for this under-researched population.

First-Line Palliative HER2-Targeted Therapy in HER2-Positive Metastatic Breast Cancer Is Less Effective After Previous Adjuvant Trastuzumab-Based Therapy

BACKGROUND

Survival of patients with human epidermal growth receptor 2 (HER2)-positive metastatic breast cancer (MBC) has improved dramatically since trastuzumab has become available, although the disease eventually progresses in most patients. This study investigates the outcome (overall survival [OS] and time to next treatment [TNT]) in MBC patients pretreated with trastuzumab in the adjuvant setting (TP-group) compared with trastuzumab-naïve patients (TN-group) in order to investigate the possibility of trastuzumab resistance.

PATIENTS AND METHODS

Patients treated with first-line HER2-targeted-containing chemotherapy were eligible for the study. A power analysis was performed to estimate the minimum size of the TP-group. OS and TNT were estimated using Kaplan-Meier curves and multivariable Cox proportional hazards models.

RESULTS

Between January 1, 2000, and June 1, 2014, 469 patients were included, of whom 82 were in the TP-group and 387 were in the TN-group. Median OS and TNT were significantly worse in the TP-group compared with the TN-group (17 vs. 30 months, adjusted hazard ratio [HR] 1.84 [1.15-2.96], p = .01 and 7 vs. 13 months, adjusted HR 1.65 [1.06-2.58], p = .03) after adjustment for age, year of diagnosis, disease-free interval, hormone receptor status, metastatic site, and cytotoxic regimens.

CONCLUSION

First-line trastuzumab-containing treatment regimens are less effective in patients with failure of adjuvant trastuzumab compared with trastuzumab-naïve patients and might be due to trastuzumab resistance. The impact of trastuzumab resistance on the response on dual HER2 blockade with trastuzumab and pertuzumab and how resistance mechanisms can be used in the optimization of HER2-targeted treatment lines need further investigation.

IMPLICATIONS FOR PRACTICE

Evidence on the efficacy of palliative trastuzumab-based therapy after failure of trastuzumab in the adjuvant setting is limited because of a minority of patients treated with adjuvant trastuzumab in clinical trials. In this study, less clinical benefit of palliative trastuzumab-based therapy was observed in patients relapsing after adjuvant trastuzumab compared with no adjuvant trastuzumab treatment. Subgroup analyses and multivariable analyses revealed that this was independent of possible confounding factors, including adjuvant taxane-treatment. This might suggest a clinically meaningful impaired efficacy of trastuzumab after previous, in this case adjuvant, trastuzumab therapy. These results could have implications for treatment decision-making after short progression-free intervals on trastuzumab-containing regimens in the palliative setting.

Trastuzumab and survival of patients with metastatic breast cancer

INTRODUCTION

Prognosis of Her2-positive breast cancer has changed since the introduction of trastuzumab for treatment in metastatic and early breast cancer. It was described to be even better compared to prognosis of Her2-negative metastatic breast cancer. The purpose of this study was to evaluate the effect of trastuzumab in our cohort. Besides the effect of adjuvant pretreatment with trastuzumab on survival of patients with metastatic Her2-positive breast cancer was analyzed.

METHODS

All patients with primary breast cancer of the Regional Breast Cancer Center Dresden diagnosed during the years 2001-2013 were analyzed for treatment with or without trastuzumab in the adjuvant and in the metastatic treatment setting using Kaplan-Meier survival estimation and Cox regression. Age and tumor stage at time of first diagnosis of breast cancer as well as hormone receptor status, grading, time, and site of metastasis at first diagnosis of distant metastatic disease were analyzed.

RESULTS

Of 4.481 female patients with primary breast cancer, 643 presented with metastatic disease. Her2-positive status was documented in 465 patients, including 116 patients with primary or secondary metastases. Median survival of patients with Her2-positive primary metastatic disease was 3.0 years (95% CI 2.3-4.0). After adjustment for other factors, survival was better in patients with Her2-positive breast cancer with trastuzumab therapy compared to Her2-negative metastatic disease (HR 2.10; 95% CI 1.58-2.79). Analysis of influence of adjuvant therapy with and without trastuzumab by Kaplan-Meier showed a trend for better survival in not pretreated patients. Median survival was highest in hormone receptor-positive Her2-positive (triple-positive) primary metastatic breast cancer patients with 3.3 years (95% CI 2.3-4.6).

CONCLUSION

Prognosis of patients with Her2-positive metastatic breast cancer after trastuzumab treatment is more favorable than for Her2-negative breast cancer. The role of adjuvant chemotherapy with or without trastuzumab warrants further research. Survival is best in triple-positive metastatic breast cancer. This will effect counseling at the time of first diagnosis of metastatic breast cancer.

Patterns of Care and Clinical Outcomes of HER2-positive Metastatic Breast Cancer Patients With Newly Diagnosed Stage IV or Recurrent Disease Undergoing First-line Trastuzumab-based Therapy: A Multicenter Retrospective Cohort Study

BACKGROUND

The aim of the study was to compare the patterns of care and clinical outcomes of HER2-positive metastatic breast cancer (MBC) patients with de novo or recurrent disease who underwent first-line trastuzumab-based therapy.

PATIENTS AND METHODS

This was a multicenter retrospective cohort study including consecutive patients with HER2-positive MBC who received first-line trastuzumab-based therapy. Analyses on treatment response and effectiveness were conducted according to type of metastatic presentation (ie, de novo vs. recurrent disease). Exploratory analyses were used to evaluate whether the use of surgery of the primary tumor in the de novo cohort influenced patients' survival.

RESULTS

From January 2000 to December 2013, 416 patients were included in the study, 113 (27.2%) presented with de novo MBC and 303 (72.8%) with recurrent disease. Compared with patients in the recurrence cohort, those in the de novo cohort had worse baseline characteristics, received more aggressive first-line treatments, and showed better survival, with an adjusted hazard ratio (HR) for progression-free survival (PFS) of 0.65 (95% confidence interval [CI], 0.43-0.97; P = .035) and for overall survival (OS) of 0.53 (95% CI, 0.30-0.95; P = .034). In the de novo cohort, the 54 patients (47.8%) who underwent surgery of the primary tumor had significantly better PFS (adjusted HR, 0.44; 95% CI, 0.26-0.72; P = .001) and OS (adjusted HR, 0.49; 95% CI, 0.26-0.93; P = .029) than those who did not undergo surgery.

CONCLUSION

Patients with de novo HER2-positive MBC showed significantly better survival outcomes than those with recurrent disease. In this population, surgery of the primary breast tumor was associated with better outcomes.

Bone metastasis risk factors in breast cancer

Bone is the single most frequent site for bone metastasis in breast cancer patients. Patients with bone-only metastasis have a fairly good prognosis when compared with patients with visceral disease. Nevertheless, cancer-induced bone disease carries an important risk of developing skeletal related events that impact quality of life (QoL). It is therefore particularly important to stratify patients according to their risk of developing bone metastasis. In this context, several risk factors have been studied, including demographic, clinicopathological, genetic, and metabolic factors. Most of them show conflicting or non-definitive associations and are not validated for clinical use. Nonetheless, tumour intrinsic subtype is widely accepted as a major risk factor for bone metastasis development and luminal breast cancer carries an increased risk for bone disease. Other factors such as gene signatures, expression of specific cytokines (such as bone sialoprotein and bone morphogenetic protein 7) or components of the extracellular matrix (like bone crosslinked C-telopeptide) might also influence the development of bone metastasis. Knowledge of risk factors related with bone disease is of paramount importance as it might be a prediction tool for triggering the use of targeted agents and allow for better patient selection for future clinical trials.

Adjuvant trastuzumab: a 10-year overview of its benefit

INTRODUCTION

Anti-HER2 targeted therapy is one of the key advances in the treatment of breast cancer that have occurred in the last 20 years. In the adjuvant setting, the use of trastuzumab has led to prolonged and sustained survival benefit with very little toxicity as also confirmed by the 10-year follow-up results from the pivotal trials. Despite the survival improvement, several key issues are not entirely resolved in this field. These issues have led to multiple research efforts in de-escalating or escalating the standard treatment with chemotherapy and 1 year of adjuvant trastuzumab. Areas covered: In this paper, we present an in depth overview on the state of the art on these key issues of refining decision-making in adjuvant anti-HER2 therapy. Expert commentary: Despite many important research efforts in the field, chemotherapy plus trastuzumab for a total duration of 1 year remains the standard of care. However, recent data showed that besides standard anthracycline- and taxane-based cytotoxic therapy, alternative chemotherapy regimens can now be proposed to patients with small tumors without nodal involvement and to women at high-risk of developing cardiotoxicity. Of note, besides HER2 itself, biomarkers predicting patients who may truly benefit from anti-HER2 agents are still lacking.

Twenty years of anti-HER2 therapy-associated cardiotoxicity

Over the past 20 years, the prognosis of HER2-positive breast cancer has been transformed by the development of anti-HER2 targeted therapies. In early clinical trials of trastuzumab (ie, the first anti-HER2 agent to be developed) cardiotoxicity became a major concern. In the first published phase 3 trial of trastuzumab, 27% of patients receiving anthracyclines and trastuzumab experienced cardiac events and 16% suffered from severe congestive heart failure. In subsequent trials conducted in advanced and early settings, the incidence of cardiac events was reduced through changes in chemotherapy regimens, more strict patient selection and close cardiac assessment. However, cardiotoxicity remains a significant problem in clinical practice that is likely to increase as new agents are approved and exposure times increase through improved patients' survival. Though numerous trials have led to improved understanding of many aspects of anti-HER2 therapy-related cardiotoxicity, its underlying physiopathology mechanisms are not well understood. The purpose of this article is to provide an in-depth review on anti-HER2 therapy-related cardiotoxicity, including data on both trastuzumab and the recently developed anti-HER2 targeted agents.