HER2-low Unresectable and/or Metastatic Breast Cancer in Russia

Study Overview
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Brief Summary
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Planned study population consists of approximately 3,150 adult patients with HER2-negative (IHC 0, + or IHC2+/ISH-) unresectable or metastatic BC enrolled to the study in order to obtain approximately 2,000 patients with confirmed HER2 low status (IHC1+ or IHC2+/ISH ).

Official Title
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A Multicenter Observational Retrospective Study of Therapeutic Approaches and Clinical Outcomes in Real Clinical Practice in Russian Patients With Human Epidermal Growth Factor Receptor 2 (HER2)-Low Unresectable and/or Metastatic Breast Cancer

Conditions
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Breast Cancer

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with confirmed diagnosis of unresectable and/or metastatic BC established between the 1st July 2021 and the 1st July 2022. Patients have HER2-negative status (IHC0, IHC1+, IHC2+/ISH-) obtained in the local laboratory. -. Patients have an adequate archival tumor sample and slides suitable for reassessment HER2 status* by the reference laboratory. Patients have documented hormonal status (ER, PR) IHC score. Age ≥ 18 years at the time of inclusion. Patients provided written consent allowing for data and samples to be used in the future and this study would be covered by the consent for future use in accordance with ICH GCP, GPP (Good Pharmacoepidemiology Practices) and local law prior to inclusion in the study. If the patient is deceased, a waiver may be accepted Exclusion Criteria: Patients with previous HER2 positive status in the anamnesis at the diagnosis or after the diagnosis of breast cancer. Presence of other malignancies within period since diagnosis until the timepoint of data collection. Patients receiving trastuzumab deruxtecan currently or received in anamnesis. The participation in any randomised controlled trial within period since diagnosis until end of study.
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To study the overall prevalence of HER2-low among patients with HER2-negative mBC, based on reassessment of historical HER2 fixed tissue IHC stained slides assay in the Russian Federation |  | 12 months | 
| To study the clinical-pathological, histopathological and demographic profiles of patients of HR-positive and HR-negative HER2-low status among unresectable and/or mBC patients identified as HER2-negative HR-positive/negative | Clinical and demographic data, as well as other study variables will be presented as frequencies or percentages, or as the mean value, standard deviation, median, quantiles, minimum and maximum, depending on the type of variable (continuous or categorical) for the total sample and all subgroups (if applicable). | 12 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To describe data on the diagnostic algorithms and therapeutic tactics in patients with HR-positive and HR-negative HER2-low unresectable and/or mBC in routine practice in the Russian Federation | Data on methods used for diagnosis will be presented as frequencies or percentages, or as the mean value, standard deviation, median, quartiles, minimum and maximum, depending on the type of variable (categorical or continuous) for the total sample and all subgroups | 12 months | 
| To describe data on the treatment approach in patients with HR-positive and HR-negative HER2-low unresectable and/or mBC in routine practice in the Russian Federation, and the sequence of therapy administration (HR-positive and HR-negative). | Data on methods used for anticancer and concomitant treatment will be presented as frequencies or percentages, or as the mean value, standard deviation, median, quartiles, minimum and maximum, depending on the type of variable (categorical or continuous) for the total sample and all subgroups | 12 months | 
| To assess the treatment outcomes of patients with HR-positive and HR-negative HER2-low unresectable and/or mBC in routine practice in the Russian Federation | Data on methods used for anticancer and concomitant treatment will be presented as frequencies or percentages, or as the mean value, standard deviation, median, quartiles, minimum and maximum, depending on the type of variable (categorical or continuous) for the total sample and all subgroups | 12 months | 
| To characterize the concordance between HER2 IHC scores in local and reference laboratories after reassessment in the reference lab (IHC 0, 1+, 2+/ISH-) using the existing, and refined, criteria of ASCO/CAP definition | The frequency of concordance of IHC HER2 scores and ISH results between local and reference laboratories will be calculated along with exact 95% CIs. Cohen's Kappa statistics will be used to evaluate concordance between HER2 IHC scores in local and reference laboratories. | 12 months |