Translating CLEOPATRA into routine practice - National treatment patterns and survival for patients with HER2-positive metastatic breast cancer

Sep 22, 2026

Amplification of the HER2 gene occurs in 15–20% of breast cancers and historically predicts poor prognosis. The CLEOPATRA trial showed that adding pertuzumab to trastuzumab plus chemotherapy improves median overall survival by 15.7 months, but strict trial criteria may limit real-world generalizability. This study uses nationwide Norwegian registry-linked data to compare survival after treatment adoption in real practice between pre- and post-CLEOPATRA eras.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages6

Reading Time15 min

AccessFree to download

Introduction

HER2 amplification and prior trial evidence

Methods

Study population and cohort periods

Survival estimation and benchmarking

Results

Cohort characteristics

Treatment patterns over time

Overall survival outcomes

Conclusions

The Breast 89 (2026) 104852 Contents lists available at ScienceDirect The Breast journal [homepage:](homepage: www.journals.elsevier.com/the-breast)[ www.journals.elsevier.com/the-breast](homepage: www.journals.elsevier.com/the-breast) | Translating CLEOPATRA into routine practice: National treatment patterns and survival for patients with HER2-positive metastatic breast cancer
Kathrine F. Vandraas a,b,c,* , Sarah Hjortha,b , Cassia B. Trewin-Nybråtend ,
Bettina K. Andreassena, Egil S. Blix e,f, Bjørn Naumec,g , Edoardo Botteria,h , Giske Ursin i,j,k, Nathalie C. Støer a,b,**
a Department of Research, Cancer Registry of Norway, Norwegian Institute of Public Health, Oslo, Norway
b Norwegian Research Center for Women's Health, Department of Obstetrics and Gynecology, Oslo University Hospital, Oslo, Norway c Department of Oncology Oslo University Hospital, Oslo, Norway
d Department of Registration, Cancer Registry of Norway, Norwegian Institute of Public Health, Oslo, Norway
e Department of Clinical Medicine, The Arctic University of Norway, Tromsø, Norway f Department of Oncology, University Hospital of North Norway, Tromsø, Norway g Institute of Clinical Medicine, University of Oslo, Oslo, Norway
h Department of Colorectal Cancer Screening, Cancer Registry of Norway, Norwegian Institute of Public Health, Oslo, Norway i Cancer Registry of Norway, Norwegian Institute of Public Health, Oslo, Norway
j Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
k Department of Preventive Medicine, University of Southern California, Los Angeles, CA, USA | | | | --- | --- | --- | | A R T I C L E I N F O | | A B S T R A C T | | Keywords:
HER2-Positive breast cancer Real-world data CLEOPATRA | | Introduction: Amplification of the epidermal growth factor receptor 2 (HER2) gene occurs in 15-20% of breast cancers and was historically associated with poor prognosis. The CLEOPATRA trial established pertuzumab added to trastuzumab and chemotherapy as standard of care for metastatic HER2-positive breast cancer, demonstrating a 15.7-month improvement in median overall survival (OS). Strict trial inclusion criteria may limit generalizability to clinical practice. Population-based data can assess whether these survival benefits translate to real-world outcomes.
Methods: Women diagnosed with HER2-positive metastatic breast cancer in 2012–2021 were identified through the Cancer Registry of Norway and linked to health and treatment databases. Patients were categorized by treatment regimen and year of treatment initiation: pre-CLEOPATRA (2012–2014; trastuzumab ± chemotherapy) and post-CLEOPATRA (2015–2021; trastuzumab + pertuzumab ± chemotherapy). OS was estimated using Kaplan–Meier and Cox regression adjusted for clinical, and socioeconomic factors. Outcomes were benchmarked against CLEOPATRA.
Results: The cohort comprised 329 women, 23% were aged ≥65 years. Seventy-eight patients (24%) received preCLEOPATRA regimens and 251 (76%) post-CLEOPATRA regimens; 59% met minimum one CLEOPATRA exclusion criterion. First-line dual HER2 blockade increased from 0% in 2012 to 75% in 2021. Median OS improved from 69 months to 96 months post-CLEOPATRA. Four-year OS increased from 59% to 65%(adjusted hazard ratio 0.77, 95% CI 0.53–1. 12). Real-world OS was consistent with CLEOPATRA outcomes.
Conclusions: Nationwide real-world data demonstrate favorable survival outcomes following adoption of dual anti-HER2 therapy. While these findings are broadly consistent with the CLEOPATRA trial, the observational design does not allow direct assessment of equivalence between studies.
Abbreviations: all abbreviations in the abstract are standard in this field of research. | 1. Introduction HER2 amplification occurs in about 15-20% of breast cancers (BC) * Corresponding author. Department of Research, Cancer Registry of Norway, Norwegian Institute of Public Health, Oslo, Norway. ** Corresponding author. De

FAQs

What question does this study address about CLEOPATRA in routine care?

It evaluates whether the survival benefits observed in the CLEOPATRA trial translate into real-world outcomes for patients with HER2-positive metastatic breast cancer after adoption in clinical practice.

How were patients grouped in this analysis?

Women diagnosed in 2012–2021 were categorized into a pre-CLEOPATRA period (2012–2014; trastuzumab ± chemotherapy) and a post-CLEOPATRA period (2015–2021; trastuzumab + pertuzumab ± chemotherapy), based on treatment regimen and initiation year.

What were the key survival findings after implementing dual anti-HER2 therapy?

Median overall survival improved from 69 months to 96 months post-CLEOPATRA, and four-year overall survival increased from 59% to 65%, with real-world outcomes broadly consistent with CLEOPATRA.

Sep 22, 2026

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