Emulation of the MONARCH-3 Trial Using Specialty Oncology Electronic Health Records Databases

NCT07225790 | Completed FDA Drug

• 2 other identifiers: 2022P002556-ENC-MONARCH-375F40122C00181
• Study Type: observational
• Target: 3,883
• Locations: 1 country
• Sites: 1

Brief Summary

Investigators are building an empirical evidence base for real world data through large-scale emulation of randomized controlled trials. The investigators' goal is to understand for what types of clinical questions real world data analyses can be conducted with confidence and how to implement such studies.

Conditions

Advanced Breast Cancer

Outcome Measures

Primary Outcomes (1)

• Time to all-cause mortality (overall survival)

  Hazard ratio (95% CI)

  From time of initiation of therapy through the earliest of death from any cause (the primary outcome of interest) or end of data availability (depending on specialty oncology registry data provider, end of data ranges from June 2023 to April 2024)

Secondary Outcomes (1)

• Time to next treatment (TTNT)

  From time of initiation of therapy through the earliest of TTNT, death from any cause, or end of data availability (depending on specialty oncology registry data provider, end of data ranges from June 2023 to April 2024)

Study Arms (2)

Initiation of abemaciclib plus letrozole/anastrozole

Any doses and frequency observed in clinical practice will be allowed

Drug: Initiation of abemaciclib plus letrozole/anastrozole

Initiation of letrozole/anastrozole

Any doses and frequency observed in clinical practice will be allowed

Drug: Initiation of letrozole/anastrozole

Interventions

Initiation of abemaciclib plus letrozole/anastrozole DRUG

Any doses and frequency observed in clinical practice will be allowed

Initiation of abemaciclib plus letrozole/anastrozole

Initiation of letrozole/anastrozole DRUG

Any doses and frequency observed in clinical practice will be allowed

Initiation of letrozole/anastrozole

Eligibility Criteria

• Age: 18 Years+
• Sex: female
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Postmenopausal women with ER/PR-positive, HER2-negative locally advanced or metastatic breast cancer who receive treatment without curative intent

You may qualify if:

• Female aged ≥18 years at treatment initiation from 2017 - 2023
• Evidence of metastatic breast cancer (MBC)
• Documentation of Estrogen/Progesterone receptor-positive (ER/PR+)
• Documentation of Human Epidermal Growth Factor Receptor Negative (HER2-)
• ECOG performance status of 0 or 1 within 90 days of index date

You may not qualify if:

• CNS metastases
• Prior treatment with CKD4/6 inhibitor
• Prior or current treatment with chemotherapy or endocrine therapy other than letrozole/anastrozole for systemic anticancer therapy for MBC.
• Prior (neo-)adjuvant endocrine therapy
• Systemic anticancer therapy other than abemaciclib or letrozole/anastrozole
• Non-breast cancer malignancy other than basal/squamous cell skin cancer or carcinoma in situ of cervix

Sponsors & Collaborators

• Food and Drug Administration (FDA): collaborator
• Brigham and Women's Hospital: lead

Study Sites (1)

Brigham and Women's Hospital

Boston, Massachusetts, 02120, United States

Location

MeSH Terms

Interventions

Letrozole; Anastrozole

Intervention Hierarchy (Ancestors)

Nitriles; Organic Chemicals; Triazoles; Azoles; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds

Study Officials

• Shirley Wang, PhD, ScM

  Brigham and Women's Hospital

  PRINCIPAL INVESTIGATOR

• Denys Shay, MD

  Brigham and Women's Hospital

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: RETROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Study Record Dates

• First Submitted: November 5, 2025
• First Posted: November 10, 2025
• Study Start: November 3, 2025
• Primary Completion: January 31, 2026
• Study Completion: January 31, 2026
• Last Updated: February 27, 2026

Record last verified: 2025-11

Locations

US (1)