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

Characteristics and post-metastasis survival of recurrent metastatic breast cancer over time - An Australian population-based record linkage study, 2001-2016

AIM

To assess population-level characteristics and post-metastasis survival of people with recurrent metastatic breast cancer (rMBC) during a period when new publicly-subsidised adjuvant and metastatic systemic therapies became available.

METHODS

Record linkage study of females in NSW Cancer Registry (NSWCR) diagnosed with non-metastatic breast cancer (BC) in 2001-2002 (C1) and 2006-2007 (C2). We identified first rMBC from NSWCR, administrative hospital records, dispensed medicines and radiotherapy services (2001-2016). We used death registrations to estimate cumulative incidence of BC death.

RESULTS

The analysis included 2267 women with rMBC (C1:1210, C2:1057). Compared to C1, C2 had access to adjuvant HER2-targeted therapy and were more likely to have received adjuvant chemotherapy (C1:38%, C2:47%) and aromatase inhibitors (C1:52%, C2:73%, of those dispensed endocrine therapy). Five-year probability of BC death was 65% (95%CI:62-68%) in C1 and 63% (95%CI:60-66%) in C2. Regional disease (T4 or N + ) at initial BC diagnosis (C1:62%, C2:68%), and age ≥ 70 years at first metastasis (C1:27%, C2:31%) were more common in C2 and had poorer prognosis. Five-year probability of BC death was lower in C2 than C1 for treatment-defined HER2-positive BC (C1:72% 95%CI:63-79%; C2:52% 95%CI 45-60%) and those dispensed chemotherapy alone (C1:76% 95%CI:69-82, C2:67% 95%CI:59-74%, p = 0.01), but not treatment-defined hormone receptor-positive HER2-negative BC (C1:60% 95%CI 56-63%, C2:64% 95%CI 60-68%).

CONCLUSIONS

Despite less favourable prognostic characteristics in C2, BC-related survival following rMBC was similar between the two cohorts; and improved for women with HER2-positive tumours. These findings support the real-world benefits of newer treatments for rMBC.

3T-MRI Artificial Intelligence in Patients with Invasive Breast Cancer to Predict Distant Metastasis Status: A Pilot Study

BACKGROUND

The incidence of breast cancer metastasis has decreased over the years. However, 20-30% of patients with early breast cancer still die from metastases. The purpose of this study is to evaluate the performance of a Deep Learning Convolutional Neural Networks (CNN) model to predict the risk of distant metastasis using 3T-MRI DCE sequences (Dynamic Contrast-Enhanced).

METHODS

A total of 157 breast cancer patients who underwent staging 3T-MRI examinations from January 2011 to July 2022 were retrospectively examined. Patient data, tumor histological and MRI characteristics, and clinical and imaging follow-up examinations of up to 7 years were collected. Of the 157 MRI examinations, 39/157 patients (40 lesions) had distant metastases, while 118/157 patients (120 lesions) were negative for distant metastases (control group). We analyzed the role of the Deep Learning technique using a single variable size bounding box (SVB) option and employed a Voxel Based (VB) NET CNN model. The CNN performance was evaluated in terms of accuracy, sensitivity, specificity, and area under the ROC curve (AUC).

RESULTS

The VB-NET model obtained a sensitivity, specificity, accuracy, and AUC of 52.50%, 80.51%, 73.42%, and 68.56%, respectively. A significant correlation was found between the risk of distant metastasis and tumor size, and the expression of PgR and HER2.

CONCLUSIONS

We demonstrated a currently insufficient ability of the Deep Learning approach in predicting a distant metastasis status in patients with BC using CNNs.

Cardiac monitoring during trastuzumab therapy in metastatic breast cancer: early incidence of cardiac dysfunction

Trastuzumab therapy has dramatically changed breast cancer prognosis. Consensus documents recommend a close monitoring during therapy, not always feasible, especially in metastatic breast cancer. The purpose of this study is to describe trastuzumab cardiotoxicity in metastatic breast cancer patients to understand how to improve cardiovascular monitoring. We retrospectively studied metastatic breast cancer patients scheduled for trastuzumab therapy (2001-2018). All patients underwent a baseline evaluation and monitoring during therapy. Cardiotoxicity was defined as symptomatic heart failure or asymptomatic decrease in left ventricular ejection fraction > 10% from baseline and < 53%. Ninety-two women were included, mean age 61 years (±14.43), median follow-up 42.5 months (IQR 26-74). Fourteen percent developed cardiotoxicity:  two heart failure with preserved left ventricular ejection fraction, three heart failure with reduced left ventricular ejection fraction, and eight asymptomatic decreased in left ventricular ejection fraction. Eighty-one percent of cardiac dysfunction cases occurred within the first 4 years and on median of 31 months from trastuzumab initiation. Thus, in metastatic breast cancer patients, trastuzumab-mediated cardiotoxicity occurred more frequently during the first 4 years. These data should be considered to optimize follow-up protocols.

Effectiveness of Trastuzumab for Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer in a Real-Life Setting: One Decade of Experience Under National Treatment Coverage Regulations

PURPOSE

Trastuzumab has shown an overall survival (OS) benefit in patients with human epidermal growth factor receptor 2 (HER2)–positive breast cancer (BC), in both the adjuvant and the metastatic setting. We assessed the effectiveness of trastuzumab in patients treated in daily practice according to national treatment coverage protocols and compared our results with those reported by randomized clinical trials. These coverage protocols included patient selection criteria similar to those of those clinical trials and were developed by the Uruguayan National Resource Fund (FNR), the agency that has funded these prescriptions for more than a decade.

PATIENTS AND METHODS

We included all patients with HER2-positive BC treated with trastuzumab under FNR coverage approved between January 1, 2006, and December 31, 2016. The source of data was the FNR database, and primary outcome was OS, analyzed through Cox proportional hazards regression analysis.

RESULTS

A total of 1,944 women were included: 1,085 women (55.8%) were postmenopausal and 1,240 (63.7%) had HER2 and hormone receptor–positive BC. Trastuzumab was administered as adjuvant therapy to 1,233 patients (63.5%), of whom 154 also received it as a neoadjuvant treatment. Three hundred nineteen patients (16.4%) received trastuzumab for advanced disease. Five-year OS in the adjuvant setting was 86.4% (95% CI, 84.0% to 88.7%). The median survival of patients with advanced BC was 25.1 months (95% CI, 10.1 to 42.5 months).

CONCLUSION

Our survival results are not inferior to those reported in clinical trials, in both adjuvant and advanced settings. Importantly, these results support the relevance and the feasibility of treating patients in routine practice, following coverage protocols based on patient selection criteria and methods supported by positive clinical trials. In addition, these results favor quality and appropriate access to BC treatment in our country.

Gaps in Care and Support for Patients With Advanced Breast Cancer: A Report From the Advanced Breast Cancer Global Alliance

PURPOSE

Although new therapeutic options continue to improve disease-related outcomes in advanced breast cancer (ABC), enhanced focus is needed to improve quality of life for patients currently living with ABC.

METHODS

In November 2019, a multidisciplinary workshop to explore patient perceptions of their information and support needs was held at the ABC Global Alliance Annual Meeting in Lisbon, Portugal. Ninety-two attendees from 27 countries participated in the workshop.

RESULTS

Several key unmet needs were identified and discussed in the workshop, including the following: (1) Significant patient knowledge gaps exist related to the diagnosis and management of ABC, and the availability of patient-focused information to support these gaps in knowledge remains limited. (2) The development of meaningful relationships between patients and health care professionals, and the role of patients in decision making, is often overlooked for patients with ABC. (3) Multidisciplinary care approaches are crucial for patients with ABC; however, these often lack effective coordination. (4) Access to clinical trials for ABC also remains limited. (5) Caregivers, friends, and family members do not receive sufficient guidance to support patients with ABC and manage their own well-being.

CONCLUSION

The variety of unmet needs explored in the workshop demonstrates that patients with ABC still face considerable challenges related to quality of care and support, which will not be resolved until tangible action is taken. Issues highlighted in the workshop should be prioritized by working groups to shape the development of community-based solutions. There is a need for the global community to act proactively to maximize awareness of these ongoing unmet needs and existing resources, while socializing and building new initiatives and resources that will help to close these gaps for patients.

Trastuzumab emtansine for HER2-positive metastatic breast cancer: Outcomes from a whole-of-population Australian cohort

Purpose

We aim to describe the treatment patterns and overall survival (OS) outcomes in patients receiving trastuzumab emtansine (T-DM1) for HER2-positive metastatic breast cancer (HER2+MBC) in routine clinical care.

Methods

Retrospective, whole-of-population cohort study of people initiating T-DM1 for HER2+MBC between October 2015 and May 2019 in Australia. We used dispensing claims to estimate time-to-T-DM1 initiation, duration of treatment, and treatments administered prior to and following T-DM1 therapy. We estimated OS from T-DM1 initiation and stratified results based on whether patients received first- or second-line T-DM1 treatment. We benchmarked outcomes to those reported in the pivotal, EMILIA trial.

Results

345 patients initiated T-DM1: 309 as second-line therapy for HER2+MBC and 36 as first-line therapy. 51% of patients had received endocrine therapy and 98% of second-line patients received pertuzumab prior to starting T-DM1. The median age was 57 years (53 in EMILIA); median time-to-T-DM1 initiation from start of HER2-targeted therapy for HER2+MBC was 11.6 months (IQR: 7.9–16.6); median duration of T-DM1 treatment was 6.5 months (3.1–13.5; 7.6 months in EMILIA), and median OS was 19.3 months (7.9–29.5; 29.9 months in EMILIA).

Conclusions

Our findings highlight differences in patient characteristics (older, more previous pertuzumab therapy) and outcomes (shorter OS) from the T-DM1 pivotal trial and provide real-world estimates that can inform patient, clinician and policy, decisions around the use of HER2-targeted therapies in routine clinical care.

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Real-world T-DM1 recipients are older than trial participants.

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Real-world T-DM1 recipients have more prior pertuzumab exposure than trial participants.

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Median overall survival was 10 months shorter than that reported from the trial.

Cardiac assessment in Australian patients receiving (neo)adjuvant trastuzumab for HER2-positive early breast cancer: a population-based study

PURPOSE

Cardiac function assessment is important for detecting and managing trastuzumab-associated cardiotoxicity. Our study estimates rates and predictors of cardiac assessment among patients receiving trastuzumab for HER2-positive early breast cancer (HER2+EBC) in Australia.

METHODS

We conducted a retrospective cohort study of Australians initiating (neo)adjuvant trastuzumab for HER2+EBC between 1 January 2015 and 15 April 2019. We used administrative claims to determine the number of patients receiving guideline-recommended assessment, i.e. evidence of baseline cardiac assessment (between 120 days before and 30 days after trastuzumab initiation) and regular on-treatment cardiac assessments (at least every 120 days). We examined factors associated with baseline and regular on-treatment cardiac assessment.

RESULTS

Our study includes 5621 patients (median age 56 years), of whom 4984 (88.7%) had a baseline cardiac function test. Among 4280 patients with at least 12 months of follow-up, 2702 (63.1%) had guideline-recommended cardiac assessment. Rates of guideline-recommended assessment increased with later year of diagnosis (60.9% in 2015 vs 68.3% in 2018, OR 1.34, 95% CI 1.06-1.69). Patients with higher baseline comorbidities and greater socioeconomic disadvantage were less likely to have guideline-recommended cardiac assessment. Cardiac assessment practices varied by State/Territory. There was no association between baseline cardiac risk or anthracycline use and the likelihood of receiving guideline-recommended cardiac assessment.

CONCLUSION

The majority of patients receiving (neo)adjuvant trastuzumab had guideline-recommended baseline and on-treatment cardiac assessment. Variations in cardiac assessment predominantly related to system-level factors, such as year of diagnosis and geography, rather than individual patient factors.

Survival and cardiac toxicity in patients with HER2-positive, metastatic breast cancer treated with trastuzumab in routine clinical practice

AIMS

We sought to describe survival outcomes and toxicities of trastuzumab in real-world patients with HER2-positive, metastatic breast cancer (MBC) and compare these to a recent systematic review of clinical trials.

METHODS

We searched the medical records of three Sydney cancer centers for patients with HER2-positive, MBC starting trastuzumab from January 2001 to March 2017. We recorded patient, tumor, and treatment characteristics; survival times from start of palliative trastuzumab; and rates of cardiac toxicity. Survival distribution was summarized using the following percentiles (represented scenario): 90th (worst-case), 75th (lower-typical), 25th (upper-typical), and 10th (best-case). Survival times were compared to recent review of HER2-positive MBC randomized trials. Factors associated with survival were assessed with Cox models.

RESULTS

Characteristics of the 126 patients were: median age 53 years, ER positive cancer (50%), de-novo metastatic disease (23%), prior adjuvant trastuzumab (15%), liver metastases (37%), and brain metastases (23%). The median duration of first-line trastuzumab was 11 months (interquartile range, (IQR) 5-27). Survival times in months (vs the systematic review) were: 90th percentile 8 (9); 75th percentile 16 (19); and median 34 (33). Follow-up duration was insufficient to estimate the 25th and 10th percentiles, similar to the systematic review. Liver metastases were associated with shorter survival (HR = 1.74, 95% CI, 1.1-2.76, P = .02). Seventy percent of patients had a baseline cardiac assessment. Five patients (3.9%) developed symptomatic cardiac toxicity, similar to clinical trials.

CONCLUSION

Survival and cardiac toxicity rates for women starting trastuzumab in routine practice were comparable to clinical trials. Oncologists can use clinical trial data as a reference point when explaining survival outcomes to women with HER2-positive MBC.

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.

CinéBreast-factors influencing the time to first metastatic recurrence in breast cancer: Analysis of real-life data from the French ESME MBC database

Purpose

The Time to First Metastatic Recurrence (TFMR) could be considered as an indirect reflection of the tumour growth kinetics which plays an important role in cancer. Molecular subtypes such as expression of estrogen receptor are known predictive factors of TFMR. The CinéBreast study aimed to identify predictive factors of the time to TFMR.

Methods

The French Epidemiological Strategy and Medical Economics (ESME) Metastatic Breast Cancer (MBC) Database (NCT03275311) was used, which contains data from a cohort of metastatic breast cancer patients from 2008 to 2016 using retrospective data collection. It is a national multi-centre database. The impact of TFMR on overall survival (OS) since first metastasis was also evaluated.

Results

Among 16 702 patients recorded in the ESME MBC database, 10 595 had an initially localised breast cancer with hormone receptor (HR) and HER2 status available, with a metastatic recurrence. Median follow up was 56 months. Median TFMR was 59 months (<24: 20%, 24–60: 31%, 60–120: 25%, >120: 24%). HER2+ and TNBC were respectively 4 times and 12 times (p < 0.0001) more likely to have a recurrence within 2 years when compared to the luminal subgroup. Short TFMR and HR-/HER2-subtype significantly correlated with a poor OS in multivariate analysis.

Some patients with MBC (20% in HER2+, 10% in ER+/HER2-and <5% in the ER-/HER2-) were long-term survivors in all 3 subgroups.

Conclusions

In this large-scale real-life data study, patients with a TNBC metastatic recurrence had a shorter TFMR. Short TFMR significantly correlated with worse overall survival.

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ESME is a large-scale real-life database of 16 702 metastatic breast cancer patients.

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A short time to first metastatic recurrence is associated with poor overall survival.

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Triple-negative tumours were more likely to recur early than HR+ and HER2+ tumours.

Trastuzumab use in older patients with HER2-positive metastatic breast cancer: outcomes and treatment patterns in a whole-of-population Australian cohort (2003-2015)

Background

Older patients with HER2-positive metastatic breast (HER2 + MBC) cancer are underrepresented in clinical trials. We aim to describe the treatment patterns and overall survival (OS) for older women receiving trastuzumab for HER2 + MBC.

Methods

Retrospective, whole-of-population cohort study using demographic, dispensing, and medical services data for Australian women ≥ 65 years initiating trastuzumab for HER2 + MBC between 2003 and 2015. We describe time-on-trastuzumab; type and timing of other cancer treatments; rates of cardiac monitoring; and OS from trastuzumab initiation for HER2 + MBC.

Results

Of 5404 women initiating trastuzumab for HER2 + MBC, 1583 (29%) were ≥ 65 years old, and the proportion of older patients increased from 20% in 2003 to 38% in 2015. The median age for older women was 73 years and 516 (33%) were ≥ 75 years. Most older patients (92%) received ≥3medicines for comorbidities other than cancer. Median (IQR) time on trastuzumab was 14.1 months (5.9–32.1) and on all chemotherapy was 5.6 months (3.3–10.8). 74% received ≥1 chemotherapy agent and 56% received endocrine therapy. Half (49%) of patients had a cardiac assessment prior to initiating trastuzumab and overall 1228 (76%) had ≥1 cardiac assessment during the study period. At a median follow-up of 6 years, 73% of patients had died and the median OS was 25.6 months (IQR 10.7–58.7).

Conclusions

Older patients comprise a growing proportion of patients treated with HER2-targeted therapies in the real-world but they remain underrepresented in trials of these agents. Few trials report duration or OS estimates for older patients but our estimates are similar to those from trials that have. Although cardiac monitoring was a requirement of accessing trastuzumab during our study period, many patients did not undergo a cardiac assessment.

Paclitaxel-Trastuzumab Mixed Nanovehicle to Target HER2-Overexpressing Tumors

Paclitaxel is one of the most widely used chemotherapeutic agents thanks to its effectiveness and broad spectrum of antitumor activity. However, it has a very poor aqueous solubility and a limited specificity. To solve these handicaps, a novel paclitaxel-trastuzumab targeted transport nanosystem has been developed and characterized in this work to specifically treat cancer cells that overexpress the human epidermal growth factor receptor-2 (HER2). Methods: Alginate and piperazine nanoparticles were synthetized and conjugated with paclitaxel:β-cyclodextrins complexes and trastuzumab. Conjugated nanoparticles (300 nm) were characterized and their internalization in HER2-overexpressing tumor cells was analyzed by immunofluorescence. Its specific antitumor activity was studied in vitro using human cell lines with different levels of HER2-expression. Results: In comparison with free paclitaxel:β-cyclodextrins complexes, the developed conjugated nanovehicle presented specificity for the treatment of HER2-overpressing cells, in which it was internalized by endocytosis. Conclusions: It seems that potentially avoiding the conventional adverse effects of paclitaxel treatment could be possible with the use of the proposed mixed nanovehicle, which improves its bioavailability and targets HER2-positive cancer cells.

Long-Term Safety and Real-World Effectiveness of Trastuzumab in Breast Cancer

Trastuzumab is a milestone in the treatment of human epidermal growth factor receptor 2 positive (HER2+) breast cancer (BC), in both the early and metastatic settings. Over the last two decades, clinical trials have established the good safety profile of trastuzumab. Cardiotoxicity remains the most frequent adverse event, more commonly exemplified by an asymptomatic decline in the left ventricular ejection fraction rather than congestive heart failure. Results from several long-term (>5 years) safety analyses have been recently published, with the inherent evidence substantially confirming the findings from previous trials. The clinical experience gained over the years in the use of trastuzumab has also fueled a number of observational studies focused on the effectiveness of this drug in the real-world settings. We herein reviewed the evidence available from tree major databases, namely, PubMed, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL), to explore and critically discuss key issues related to the long-term safety and effectiveness of trastuzumab in clinical practice.

Metastatic breast cancer incidence, site and survival in Australia, 2001-2016: a population-based health record linkage study protocol

INTRODUCTION

Advances in systemic therapy for early and metastatic breast cancer (BC) over the last two decades have improved patients' survival, but their impact on metastatic disease outcomes at a population level is not well described. The aim of this study is to investigate changes in the incidence, site and survival of metastatic disease for women with a first diagnosis of BC in 2001-2002 vs 2006-2007.

METHODS AND ANALYSIS

Population-based retrospective cohort study of women with first primary invasive BC registered in the New South Wales (NSW) Cancer Registry in 2001-2002 and 2006-2007. We will use linked records from NSW hospitals, dispensed medicines, outpatient services and death registrations to determine: women's demographic and tumour characteristics; treatments received; time to first distant metastasis; site of first metastasis and survival. We will use the Kaplan-Meier method to estimate cumulative incidence of distant metastasis, distant recurrence-free interval and postmetastasis survival by extent of disease at initial diagnosis, site of metastasis and treatment-defined tumour receptor type (hormone receptor-positive, human epidermal growth factor receptor-2-positive, triple negative). We will use Cox proportional hazards regression to estimate the relative effects of prognostic factors, and we will compare systemic therapy patterns by area-of-residence and area-level socioeconomic status to examine equity of access to healthcare.

ETHICS AND DISSEMINATION

Research ethics committee approval was granted by the Australian Institute of Health and Welfare (#EO2017/2/255), NSW Population and Health Services (#HREC/17/CIPHS/19) and University of Notre Dame Australia (#0 17 144S). We will disseminate research findings to oncology, BC consumer and epidemiology audiences through national and international conference presentations, lay summaries to BC consumer groups and publications in international peer-reviewed oncology and cancer epidemiology journals.

Adherence to prescribing restrictions for HER2-positive metastatic breast cancer in Australia: A national population-based observational study (2001-2016)

BACKGROUND

Targeted cancer therapy is often complex, involving multiple agents and chemotherapeutic partners. In Australia, prescribing restrictions are put in place to reflect existing evidence of cost-effectiveness of these medicines. As therapeutic options continue to expand, these restrictions may not be perceived to align with best practice and it is not known if their use in the real-world clinic adheres to these restrictions. We examined the treatment of women receiving trastuzumab for HER2-positive metastatic breast cancer (HER2+MBC) to determine the extent to which treatment adhered to national prescribing restrictions.

PATIENTS AND METHODS

Our population-based, retrospective cohort study used dispensing records for every Australian woman initiating publicly-subsidised trastuzumab for HER2+MBC between 2001-2013, followed through 2016. We used group-based trajectory models (GBTMs) to cluster patients, first on their patterns of trastuzumab exposure, and then on their patterns of lapatinib and chemotherapy exposure. We described the characteristics of patients within each cluster, and examined their treatments and combinations of treatments to determine restriction adherence.

RESULTS

Of 5,052 patients initiating trastuzumab, 1,795 (36%) received at least one non-adherent HER2-targeted treatment. The most common non-adherent treatments were trastuzumab combinations involving vinorelbine (24% of non-adherent treatments); capecitabine (24%); and anthracyclines (10%). Non-adherent lapatinib use was observed in 4% of patients. GBTM identified three trastuzumab exposure clusters, each containing three further sub-clusters. The largest proportions of non-adherent treatments were in sub-clusters with longer trastuzumab exposure and more non-taxane chemotherapy. Patients in these sub-clusters were younger than those in sub-clusters with less non-adherent treatment.

CONCLUSIONS

Our study highlights that, even during the relatively simpler treatment era of our study period, a substantial amount of treatment did not adhere to prescribing restrictions. As more trials are conducted exploring pertuzumab and T-DM1 in combination with different chemotherapies and other HER2-targeted therapies, the regulation and funding of HER2-targeted treatment will become more challenging.

Long-term survival in trastuzumab-treated patients with HER2-positive metastatic breast cancer: real-world outcomes and treatment patterns in a whole-of-population Australian cohort (2001-2016)

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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