How well patients stick to aromatase inhibitor treatment, with or without abemaciclib, for early HR+/HER2- breast cancer

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

Observational Institute of Oncology Ljubljana · NCT06650423

This study tests whether people with early HR+/HER2- breast cancer stick to aromatase inhibitor treatment more or less when they also take abemaciclib.

Quick facts

Study typeObservational
Enrollment319 (estimated)
Ages18 Years to 99 Years
SexFemale
SponsorInstitute of Oncology Ljubljana Academic / other
Locations1 site (Ljubljana)
Trial IDNCT06650423 on ClinicalTrials.gov

What this trial studies

This is an observational study comparing medication adherence and treatment persistence between patients taking adjuvant aromatase inhibitors alone and those taking aromatase inhibitors together with abemaciclib. Participants are women with early HR+/HER2- breast cancer receiving adjuvant therapy for up to 18 months at the Institute of Oncology Ljubljana. The study will relate adherence and discontinuation rates to patient-reported measures such as quality of life, cognitive function, and attitudes toward therapy, as well as demographic and treatment history factors. Findings aim to clarify whether the addition of abemaciclib, with its distinct safety profile, is associated with different real-world adherence patterns.

Who should consider this trial

Good fit: Women with early HR+/HER2- breast cancer who are receiving adjuvant aromatase inhibitor therapy, with or without abemaciclib, for no more than 18 months, are treated at the Institute of Oncology Ljubljana, have Slovenian health insurance, understand Slovenian, and provide informed consent.

Not a fit: Patients with metastatic HR+/HER2- breast cancer, those previously treated with an aromatase inhibitor for early disease before the current adjuvant line, or patients treated outside the Institute of Oncology Ljubljana or without Slovenian insurance/language ability are not eligible and unlikely to benefit from this study's findings.

Why it matters

Potential benefit: If successful, the study could reveal adherence barriers and guide interventions to help patients stay on effective adjuvant therapy, potentially lowering recurrence risk.

How similar studies have performed: Adjuvant CDK4/6 inhibitors such as abemaciclib have shown improvement in invasive disease-free survival, but direct real-world comparisons of adherence between aromatase inhibitor alone versus aromatase inhibitor plus abemaciclib remain sparsely characterized, so this question is relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
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

Where this trial is running

Ljubljana

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Early Breast CancerHormone Receptor Positive TumorHER2-negative Breast Cancerbreast cancermedication adherenceCDK4/6HR+HER2-
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.