Real-World Treatment Patterns and Outcomes in HER2-Altered Metastatic Breast Cancer Patients in the United States

NCT07342309 | Active Not Recruiting

• 1 other identifier: 1479-0045
• Study Type: observational
• Target: 7,933
• Locations: 1 country
• Sites: 1

Brief Summary

This study aims to address the following key objectives in patients with HER2-altered mBC: Primary objectives

• Estimate the prevalence of human epidermal growth factor receptor 2 positive (HER2+), human epidermal growth factor receptor 2 (HER2) mutation, cooccurrence of HER2+ and HER2 mutation among adult patients with metastatic breast cancer (mBC)
• Among mBC patients with HER2+ and HER2 mutation, describe the following:
• Baseline demographic and clinical characteristics
• Treatment patterns during follow-up including 1L through fifth-line (5L) settings
• Real-world overall survival (rwOS) for 1L through 5L Secondary objectives \- Among mBC patients with HER2+ and HER2 mutation, examine the following (as permissible in the study data):
• Real-world progression-free survival (rwPFS)
• Real-world time to discontinuation (rwTTD)
• Real-world time to next treatment (rwTTNT)
• Real-world overall response rate (rwORR)

Conditions

Metastatic Breast Cancer

Outcome Measures

Primary Outcomes (1)

• Real-world overall survival (rwOS)

  OS as an event for each patient will be defined as the date of death minus the index date + 1. For patients with no record of death, OS will be censored at the last visit date, defined as the date of the last visit of any type prior to data cutoff. Month and year of death are noted in the Flatiron Discovery Clinico-Genomic Database (CGDB); the day of death will be imputed as the midpoint (15 th) of the month of death. Endpoint will be assessed separately from the study index date (mBC diagnosis) and each of the line of therapy (LOT) index dates.

  Up to 15 years

Secondary Outcomes (4)

• Real-world time to treatment discontinuation (rwTTD)

  Up to 15 years

• Real-world time to next treatment (rwTTNT)

  Up to 15 years

• Real-world overall response rate (rwORR)

  Up to 15 years

• Real-world progression-free survival (rwPFS)

  Up to 15 years

Study Arms (3)

Metastatic breast cancer cohort (mBC)

Adult patients (\>=18 years) with confirmed diagnosis of recurrent or de novo metastatic breast cancer (mBC) who were diagnosed between January 1, 2018, through March 31, 2024 (1 year prior to the data cutoff date, March 31, 2025) in the Flatiron Solid Tumor Discovery Clinico-Genomic Database (CGDB).

HER2-positive subcohort (mBC HER2+)

Patients meeting eligibility of the mBC cohort. Evidence of HER2 positive (HER2+) as defined by immunohistochemistry (IHC)/in situ hybridization (ISH) * IHC 3+ or * IHC 2+ and evidence of HER2 amplification by ISH or * ISH+ without further information on IHC.

HER2-mutant subcohort (mBC HER2-mutant)

Patients meeting eligibility of the mBC cohort. Evidence of NGS short variant alterations at any time in the database, regardless of the functional type, which includes missense, nonsense, frameshift, nonframeshift, or splice variants. Patients who are not included in the HER2+ subcohort.

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adult patients (\>=18 years) with confirmed diagnosis of recurrent or de novo metastatic breast cancer (mBC) who were diagnosed between January 1, 2018, through March 31, 2024 (1 year prior to the data cutoff date, March 31, 2025) in the Flatiron Solid Tumor Discovery Clinico-Genomic Database (CGDB).

You may qualify if:

• Overall metastatic breast cancer (mBC) cohort (total population):
• Histologically or cytologically confirmed diagnosis of breast cancer (BC)
• Patient has at least 2 documented clinical visits in the Flatiron network, on different days, during the study period from 1 January 2011 through 31 March 2025
• Initial diagnosis of de novo or recurrent mBC established during the case selection window from 1 January 2018 through 31 March 2024 (1 year prior to the data cutoff date, 31 March 2025)
• \-- The date of initial mBC diagnosis will define the study index date
• Aged ≥ 18 years at the study index date
• Human epidermal growth factor receptor 2 (HER2)-positive subcohort (mBC HER2+):
• Patients meeting eligibility for the mBC cohort
• Patients can be HER2-mutant or HER2 nonmutant
• Evidence of HER2+ as defined by immunohistochemistry (IHC)/in situ hybridization (ISH) based on a test performed within 180 days before or 180 days after the index date. If a patient does not have any IHC/ISH test during the 180-day periods before or after the index date, then tests performed at any time in the pre-index date period will be examined and any evidence of HER2+ status will classify the patient as HER2+.
• IHC 3+ or IHC 2+ and evidence of HER2 amplification by ISH or ISH+ (without further information on IHC) according to American Society of Clinical Oncology/College of American Pathologists guidelines.
• The sample date will be used to define biomarker status. If the sample date is missing, the report date will be used.
• HER2-mutant subcohort (mBC HER2-mutant):
• Patients meeting eligibility for the mBC cohort
• HER2-mutant: Patients are classified as having an HER2 mutation if there is evidence of NGS short variant alterations at any time in the database, regardless of the functional type, which includes missense, nonsense, frameshift, nonframeshift, or splice variants.

You may not qualify if:

• mBC cohort (total population):
• To ensure adequate treatment and outcome data, any patient without a visit or medication record (i.e., medication order/administration or LOT) within 90 days of mBC diagnosis (i.e., the time window from 90 days before to 90 days after the mBC diagnosis).
• HER2+ subcohort (mBC HER2+):
• \- None (other than those applicable for the mBC cohort).
• HER2-mutant subcohort (mBC HER2-mutant):
• \- Patients who are included in the HER2+ subcohort.

Sponsors & Collaborators

• Boehringer Ingelheim: lead

Study Sites (1)

Ridgefield

Ridgefield, Connecticut, 06877, United States

Location

Related Links

• Related Info

MeSH Terms

Conditions

Breast Neoplasms

Condition Hierarchy (Ancestors)

Neoplasms by Site; Neoplasms; Breast Diseases; Skin Diseases; Skin and Connective Tissue Diseases

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: RETROSPECTIVE
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: January 8, 2026
• First Posted: January 15, 2026
• Study Start: September 30, 2025
• Primary Completion (Estimated): June 30, 2026
• Study Completion (Estimated): June 30, 2026
• Last Updated: February 10, 2026

Record last verified: 2026-02

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)