A Study of Real-World Treatment Patterns and Outcomes Among HR+/HER2- Metastatic Breast Cancer Patients Treated With First-Line CDK4/6 Inhibitors

Real World Treatment Patterns and Outcomes in HR+, HER2- Metastatic Breast Cancer Patients Treated With CDK 4/6 Inhibition in the First Line (1L) Setting

The aim of this study was to evaluate patient profiles, treatment patterns, and outcomes of hormone receptor positive (HR+)/human epidermal growth factor receptor-2 negative (HER2-) metastatic breast cancer (mBC) patients treated with a 1L cyclin dependent kinase 4/6 inhibitor (CDK4/6i) in the real-world setting.

Study Overview

• Status: Completed
• Conditions: Breast Cancer

• Study Type: Observational
• Enrollment (Actual): 480

Contacts and Locations

Study Locations

• United States
  • New Jersey
    • East Hanover, New Jersey, United States, 07936
      • Novartis

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

HR+/HER2- mBC patients who received 1L CDK4/6i treatment and have a medical record in the real-world evidence database.

Description

Inclusion criteria:

• A diagnosis of mBC based on at least two diagnoses of breast cancer (International Classification of Diseases, 10th Revision, Clinical Modification [ICD-10-CM] code C50.xxx) along with a diagnosis of secondary malignant neoplasm (ICD-10-CM codes C77.xxx - C80.xxx except C79.8 or C79.81, reporting of a metastatic site by curation), in the period prior to or on the index date.
• Patients with HR+/HER2- status.
• Use of either ribociclib, palbociclib, or abemaciclib in 1L treatment for mBC.
• Continuous care at the contributing practices. Patients with a minimum of two visits up to and including the index date.

Exclusion criteria:

• Use of any prior CDK4/6i before the index date.
• Prior 1L treatment, other than CDK4/6i, in mBC including treatment with endocrine therapy (ET) either with tamoxifen, aromatase inhibitors (AI; anastrozole, exemestane, or letrozole) or fulvestrant. For it to be considered 1L in mBC, the diagnosis of mBC must have preceded treatment initiation, or was indicated so in unstructured data.
• Diagnosis of cancer other than breast cancer and/or mBC on or prior to the index.
• Evidence of participation in a clinical trial at any time during the study observation period.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
CDK4/6i Cohort; Adult HR+/HER2- mBC patients treated with 1L ribociclib, palbociclib, or abemaciclib.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number and Percentage of Patients Treated With 1L Ribociclib by Demographic Category	Demographics included: Age group; Sex; Race; Ethnicity; Geographical region; Payer type; Year of 1L treatment initiation; De novo or recurrent mBC	Baseline
Age at 1L Ribociclib Treatment Initiation		Baseline
Among 1L Ribociclib Patients, Age at mBC Diagnosis		Baseline
Among 1L Ribociclib Patients, Age at Initial BC Diagnosis		Baseline
Interval Between mBC Diagnosis and 1L Ribociclib Initiation		Baseline
Number and Percentage of 1L Ribociclib Patients by Clinical Characteristic Category	Clinical characteristics included: Menopausal status; Eastern Cooperative Oncology Group (ECOG) performance status; Stage at initial breast cancer (BC) diagnosis; Comorbidities; QT prolongation diagnosis (yes/no); Sites of metastasis	Baseline
Among 1L Ribociclib Patients, Body Mass Index (BMI)		Baseline
Follow-up Time From 1L Ribociclib Treatment Initiation		Up to approximately 7 years and 6 months
Among 1L Ribociclib Patients, Number of Metastatic Sites per Patient at Baseline		Baseline
Among 1L Ribociclib Patients, Number of Metastatic Sites per Patient any Time During Study		Up to approximately 7 years and 6 months
Number and Percentage of 1L Ribociclib Patients by Sites of Metastasis During Follow-up		Up to approximately 7 years and 6 months
Number and Percentage of 1L Ribociclib Patients by Type of Medical Procedures Received		Baseline
Number and Percentage of 1L Ribociclib Patients With ESR1 Mutation at Baseline		Baseline
Number and Percentage of 1L Ribociclib Patients With ESR1 Mutation any Time During Study		Up to approximately 7 years and 6 months
Among 1L Ribociclib Patients, Red Blood Cell (RBC) Count		Baseline
Among 1L Ribociclib Patients, Hemoglobin Level		Baseline
Among 1L Ribociclib Patients, Hematocrit Level		Baseline
Among 1L Ribociclib Patients, White Blood Cell Count		Baseline
Among 1L Ribociclib Patients, Platelet Count		Baseline
Number and Percentage of 1L Ribociclib Patients With Neutropenia		Baseline
Among 1L Ribociclib Patients, Serum Creatinine Level		Baseline
Among 1L Ribociclib Patients, Aspartate Aminotransferase (AST) Level		Baseline
Among 1L Ribociclib Patients, Alanine Aminotransferase (ALT) Level		Baseline
Among 1L Ribociclib Patients, Alkaline Phosphatase (ALP) Level		Baseline
Among 1L Ribociclib Patients, Bilirubin Level		Baseline
Number and Percentage of 1L Ribociclib Patients by Type of Other Medications in 1L Treatment		Baseline
Interval Between Treatment Initiation and Ribociclib Initiation		Baseline
Number and Percentage of Patients by Type of Treatment Received per Line of Treatment		Up to approximately 7 years and 6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number and Percentage of 1L Ribociclib Patients by Type of First Dose Adjustment	Dose adjustments included up titration and down titration.	Up to approximately 7 years and 6 months
Among 1L Ribociclib Patients, Number of Total Dose Adjustments		Up to approximately 7 years and 6 months
Number and Percentage of 1L Ribociclib Patients by Starting Dose of Ribociclib		Baseline
Relative Dose Intensity (RDI) of Ribociclib	RDI was calculated by dividing the actual average daily dose by the recommended daily dose.	Up to approximately 7 years and 6 months
Ribociclib Dose at First Dose Adjustment		Up to approximately 7 years and 6 months
Among 1L Ribociclib Patients, Time to First Dose Adjustment		Up to approximately 7 years and 6 months
Number and Percentage of Patients by Ribociclib Dosage Received per Dose Adjustment		Up to approximately 7 years and 6 months

Collaborators and Investigators

• Sponsor: Novartis Pharmaceuticals
• Investigators: Study Director: Novartis Pharmaceuticals, Novartis Pharmaceuticals

Publications and helpful links

Helpful Links

• Link to study results

Study record dates

Study Major Dates

• Study Start (Actual): October 8, 2024
• Primary Completion (Actual): March 17, 2025
• Study Completion (Actual): March 17, 2025

Study Registration Dates

• First Submitted: March 12, 2026
• First Submitted That Met QC Criteria: March 30, 2026
• First Posted (Actual): April 6, 2026

Study Record Updates

• Last Update Posted (Actual): April 13, 2026
• Last Update Submitted That Met QC Criteria: April 7, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Ribociclib; Metastatic breast cancer; CDK4/6i
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms
• Other Study ID Numbers: CLEE011AUS74

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO