Breast cancer relapse after adjuvant CDK4/6 inhibitor therapy

Breast Cancer RElapsed in Patients Treated With Adjuvant CDK4/6 Inhibitors: Evaluation in the Real-world Setting

This project will look at people with HR+/HER2- early breast cancer who received adjuvant ribociclib or abemaciclib plus endocrine therapy to see what their tumor features and outcomes are, including those who relapse during or within 12 months after treatment.

Quick facts

• Study type: Observational
• Enrollment: 750 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: European Institute of Oncology (Academic / other)
• Locations: 18 sites (Bergamo, Italy and 17 other locations)
• Trial ID: NCT07180693 on ClinicalTrials.gov

What this trial studies

This is a multicenter observational project with retrospective and prospective phases collecting clinicopathologic data and outcomes for adults with resected HR+/HER2- early breast cancer treated with adjuvant ribociclib or abemaciclib plus endocrine therapy. The cohort includes patients who started adjuvant CDK4/6 inhibitors on or after January 1, 2021 and have ECOG performance status 0–2. Data collected will include tumor characteristics, patterns and timing of recurrence, subsequent therapies, and clinical outcomes, with special focus on relapses during or within 12 months of completing adjuvant treatment. Participating sites are in Bergamo, Brescia, and Brindisi, Italy, and data will be analyzed to describe real-world patterns and outcomes.

Who should consider this trial

Good fit: Adults (women or men) with resected HR+/HER2- early breast cancer who started adjuvant ribociclib or abemaciclib together with endocrine therapy on or after January 1, 2021 and have ECOG status 0–2 are ideal candidates.

Not a fit: Patients who are HER2-positive, who began adjuvant CDK4/6 therapy before January 1, 2021, or who are currently enrolled in another HR+/HER2- adjuvant interventional trial are unlikely to benefit from joining this observational project.

Why it matters

Potential benefit: If successful, this could help clinicians identify factors linked to early relapse after adjuvant CDK4/6 inhibitors and inform future treatment decisions for similar patients.

How similar studies have performed: Randomized trials such as monarchE have shown clinical benefit of adding abemaciclib in high-risk HR+/HER2- early breast cancer, but real-world observational data specifically describing early relapses after adjuvant CDK4/6 use remain limited.

Eligibility criteria

Inclusion Criteria:

* Female (regardless of menopausal status) or male ≥18 years of age;
* The patient has confirmed HR+, HER2-, early-stage resected invasive breast cancer candidate to adjuvant CDK4/6 inhibitors (abemaciclib or ribociclib);
* ER and PgR positivity is defined as evidence of immunohistochemical staining ≥ 1% according to ASCO/CAP recommendations; HER2 negativity is defined as expression of the membrane protein in immunohistochemistry 0 or 1+ or with a 2+ in situ hybridization (ISH) test negative as per ASCO/CAP recommendations;
* Patients who are initiating or have initiated adjuvant treatment with a CDK4/6 inhibitor (abemaciclib or ribociclib) in combination with endocrine therapy (ET). Treatment must have started on or after January 1, 2021.
* Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2;
* Consent to data treatment according to the local regulation.

Exclusion Criteria:

* Current participation in any other HR+/HER2- EBC study with any investigational products;
* Patients who have already received adjuvant treatment with a CDK4/6 inhibitor as part of a clinical trial;
* Patients unable to comply with the requirements of the study or who, in the judge of the study physician, should not be included in the study;
* Patients with a history of previous BC, with the exception of Ductal carcinoma in situ (DCIS) treated by locoregional therapy alone ≥5 years ago;
* Patients with a history of any other cancer (except non-melanoma skin cancer or carcinoma in situ of the cervix), unless in complete remission with no therapy for a minimum of 5 years from the index date, will be excluded, as well.

Where this trial is running

Bergamo, Italy and 17 other locations

• ASST Papa Giovanni XXIII — Bergamo, Italy, Italy (Not_yet_recruiting)
• ASST Spedali Civili di Brescia — Brescia, Italy, Italy (Recruiting)
• P.O. Antonio Perrino - ASL Brindisi — Brindisi, Italy, Italy (Not_yet_recruiting)
• ASST Ospedale Maggiore di Crema — Crema, Italy, Italy (Recruiting)
• ASST Lecco - PO Alessandro Manzoni — Lecco, Italy, Italy (Not_yet_recruiting)
• Asst Ovest Milanese — Legnano, Italy, Italy (Not_yet_recruiting)
• IRCCS Ospedale San Raffaele — Milan, Italy, Italy (Recruiting)
• Fondazione IRCCS Istituto Nazionale dei Tumori di Milano — Milan, Italy, Italy (Not_yet_recruiting)
• European Institute of Oncology — Milan, Italy, Italy (Recruiting)
• PO Luigi Sacco - ASST Fatebenefratelli Sacco — Milan, Italy, Italy (Recruiting)
• Azienda Ospedaliero-Universitaria di Modena — Modena, Italy, Italy (Not_yet_recruiting)
• Fondazione IRCCS San Gerardo dei Tintori — Monza, Italy, Italy (Not_yet_recruiting)
• Istituto Nazionale Tumori IRCCS Fondazione G. Pascale — Naples, Italy, Italy (Recruiting)
• ICS Maugeri IRCCS — Pavia, Italy, Italy (Recruiting)
• Policlinico San Matteo — Pavia, Italy, Italy (Not_yet_recruiting)
• Azienda USL IRCCS di Reggio Emilia — Reggio Emilia, Italy, Italy (Recruiting)
• Fondazione Policlinico Universitario Agostino Gemelli IRCCS — Roma, Italy, Italy (Not_yet_recruiting)
• Ospedale Isola Tiberina - Gemelli Isola — Roma, Italy, Italy (Recruiting)

Study contacts

• Study coordinator: Nadia Bianco, MD

Conditions Adjuvant Therapy; CDK4/6 Inhibitor