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NCT Number: NCT06650423

Adherence to Aromatase Inhibitors ± Abemaciclib Treatment in Patients With Early-stage HER2-negative Breast Cancer

Around 90% of breast cancer patients are diagnosed at an early stage and approximately 70% are hormone receptor-positive and HER2-negative (HR+/HER2-). Despite advancements in adjuvant endocrine therapy, 20-30% of early-stage breast cancer patients relapse within the first decade post-surgery. A recent clinically meaningful therapeutic option for these patients has been cyclin-dependent kinases 4/6 inhibitors (CDK4/6 inhibitors). Abemaciclib and ribociclib were assessed in the adjuvant setting, both showing improvement in invasive disease-free survival (IDFS). Abemaciclib has been approved by the FDA and EMA for HR+/HER2- early breast cancer at high risk of disease recurrence and is the first addition to the Slovenian treatment regimen in routine clinical practice.

Poor medication adherence can directly affect the effectiveness of treatment for early HR+/HER2- breast cancer. While adherence data in patients treated with aromatase inhibitors are available, the adherence rate in patients with early HR+/HER2- breast cancer taking abemaciclib remains unclear.

In this study, investigators hypothesize that patients receiving abemaciclib in combination with aromatase inhibitors will have lower medication adherence and higher discontinuation rates compared to those receiving aromatase inhibitors alone. It is expected that patients with better quality of life, better cognitive functioning, and a more positive attitude toward their therapy will demonstrate higher medication adherence rates. Adherence may also be influenced by additional factors, such as age and prior treatments.

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Key information

Conditions

Early Breast Cancer Behavior Breast Diseases Breast Neoplasms HER2-negative Breast Cancer Health Behavior Hormone Receptor Positive Tumor Medication Adherence Neoplasms Neoplasms by Site Patient Acceptance of Health Care Patient Compliance Skin Diseases Skin and Connective Tissue Diseases Treatment Adherence and Compliance

Age range

18 year–99 year

Sex eligibility

Female

Study type

Observational

Primary location

About this study

Poor medication adherence can directly affect the effectiveness of treatment for early HR+/HER2- breast cancer. While data on medication adherence in patients taking aromatase inhibitors are available, the adherence rate in patients with early HR+/HER2- breast cancer taking abemaciclib remains unclear. Due to the differing characteristics of these treatment modalities, particularly their distinct safety profiles, medication adherence and persistence may vary between them.

It is hypothesized that patients receiving abemaciclib in combination with aromatase inhibitors will have lower medication adherence and higher discontinuation rates compared to those receiving aromatase inhibitors alone. It is also expected that patients with better quality of life, better cognitive functioning, and a more positive attitude toward their therapy will demonstrate higher medication adherence rates. Additionally, factors such as age and prior treatments may contribute to adherence outcomes.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Female,
  • Early HR+/HER-2- BC,
  • Patient is receiving adjuvant therapy with an aromatase inhibitor (letrozole, anastrozole or exemestane), with or without a CDK4/6 inhibitor abemaciclib, for no more than 18 months,
  • Treatment of BC is being conducted at OIL,
  • Patient has mandatory health insurance through Health Insurance Institute of Slovenia,
  • Patient understands Slovenian language, and
  • Patient agrees to participate in the study and provides written informed consent.

Exclusion criteria

  • Metastatic HR+/HER2-negative breast cancer
  • Previous treatment for breast cancer with an aromatase inhibitor, with or without a CDK4/6 inhibitor, for early breast cancer prior to the current adjuvant treatment line

Treatment and study plan

Primary outcomes

  1. Medication adherence (Proportion of Days Covered, PDC) at Month 3

    Time frame: Month 3 after treatment initiation

    Medication adherence measured as Proportion of Days Covered (PDC), calculated from pill count data and expressed as percentage (%). Participants with PDC ≥80% will be classified as adherent. Self-reported adherence will additionally be assessed using the Medication Adherence Report Scale (MARS-5; score range 5-25, higher scores indicate better adherence).

  2. Medication adherence (Proportion of Days Covered, PDC) at Month 6

    Time frame: Month 6 after treatment initiation

    Medication adherence measured as Proportion of Days Covered (PDC), calculated from pill count data and expressed as percentage (%). Participants with PDC ≥80% will be classified as adherent. Self-reported adherence will additionally be assessed using the Medication Adherence Report Scale (MARS-5; score range 5-25, higher scores indicate better adherence).

Secondary outcomes

  1. EORTC QLQ-C30 score at Baseline

    Time frame: Baseline visit

    Quality of life assessed using the EORTC QLQ-C30 questionnaire. Scores are transformed to a 0-100 scale (higher scores on functional and global scales indicate better functioning; higher scores on symptom scales indicate greater symptom burden).

  2. EORTC QLQ-C30 score at Month 3

    Time frame: Month 3

    Quality of life assessed using the EORTC QLQ-C30 questionnaire. Scores are transformed to a 0-100 scale (higher scores on functional and global scales indicate better functioning; higher scores on symptom scales indicate greater symptom burden).

  3. EORTC QLQ-C30 score at Month 6

    Time frame: Month 6

    Quality of life assessed using the EORTC QLQ-C30 questionnaire. Scores are transformed to a 0-100 scale (higher scores on functional and global scales indicate better functioning; higher scores on symptom scales indicate greater symptom burden).

  4. EORTC QLQ-BR23 score at Baseline

    Time frame: Baseline visit

    Quality of life assessed using the EORTC QLQ-BR23 questionnaire. Scores are transformed to a 0-100 scale (higher scores on functional scales indicate better functioning; higher scores on symptom scales indicate greater symptom burden).

  5. EORTC QLQ-BR23 score at Month 3

    Time frame: Month 3

    Quality of life assessed using the EORTC QLQ-BR23 questionnaire. Scores are transformed to a 0-100 scale (higher scores on functional scales indicate better functioning; higher scores on symptom scales indicate greater symptom burden).

  6. EORTC QLQ-BR23 score at Month 6

    Time frame: Month 6

    Quality of life assessed using the EORTC QLQ-BR23 questionnaire. Scores are transformed to a 0-100 scale (higher scores on functional scales indicate better functioning; higher scores on symptom scales indicate greater symptom burden).

  7. Beliefs about Medicines Questionnaire (BMQ) score at Baseline

    Time frame: Baseline visit

    Beliefs about medicines assessed using the Beliefs about Medicines Questionnaire (BMQ). Items are rated on a 5-point Likert scale and summed to generate questionnaire scores.

  8. Beliefs about Medicines Questionnaire (BMQ) score at Month 3

    Time frame: Month 3

    Beliefs about medicines assessed using the Beliefs about Medicines Questionnaire (BMQ). Items are rated on a 5-point Likert scale and summed to generate questionnaire scores.

  9. Beliefs about Medicines Questionnaire (BMQ) score at Month 6

    Time frame: Month 6

    Beliefs about medicines assessed using the Beliefs about Medicines Questionnaire (BMQ). Items are rated on a 5-point Likert scale and summed to generate questionnaire scores.

  10. FACT-Cog score at Baseline

    Time frame: Baseline visit

    Cognitive functioning assessed using the Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog) questionnaire. Items are rated on a 0-4 scale and summed to generate domain and total scores (higher scores indicate better perceived cognitive functioning).

  11. FACT-Cog score at Month 3

    Time frame: Month 3

    Cognitive functioning assessed using the Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog) questionnaire. Items are rated on a 0-4 scale and summed to generate domain and total scores (higher scores indicate better perceived cognitive functioning).

  12. FACT-Cog score at Month 6

    Time frame: Month 6

    Cognitive functioning assessed using the Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog) questionnaire. Items are rated on a 0-4 scale and summed to generate domain and total scores (higher scores indicate better perceived cognitive functioning).

  13. Adverse events during follow-up

    Time frame: From treatment initiation through Month 6

    Number of participants experiencing at least one adverse event and total number of adverse events recorded during follow-up. Adverse events will be summarized by severity and seriousness.

Study contacts

Contact information is provided by the study sponsor or research team.

Cvetka Grašič Kuhar, PhD

CONTACT

[email protected]

00386 1 5879 090

Erika Matos, PhD

CONTACT

[email protected]

00386 1 5879 715

Sponsors and collaborators

Lead sponsor

Institute of Oncology Ljubljana

Other

Collaborators

  • University of Ljubljana

Registry information

Official study title

ONCO-ADHER: Adherence to Treatment With Aromatase Inhibitors With or Without Abemaciclib in Patients With Early-stage, Endocrine-dependent, HER2-negative Breast Cancer

Acronym: ONCO-Adher

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Oct 21, 2024
Registry last updated
Mar 6, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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